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CS Series
Electrochemical
Workstation
User’s Manual
Wuhan CorrTest Instruments Co., Ltd
Contents
1.
INTRODUCTION ..................................................................................................................... - 1 1.1
HARDWARE SPECIFICATIONS ........................................................................................................... - 1 -
1.2
ELECTROCHEMICAL SIGNAL GENERATOR ............................................................................................ - 2 -
1.3
FRONT PANEL .............................................................................................................................. - 2 -
1.4
POTENTIOSTATIC MODE ................................................................................................................. - 3 -
2.
INTRODUCTION ..................................................................................................................... - 4 2.1
SYSTEM REQUIREMENTS ................................................................................................................ - 4 -
2.2
SOFTWARE INSTALLATION............................................................................................................... - 5 -
3.
MENU .................................................................................................................................... - 5 3.1
FILE ........................................................................................................................................... - 6 -
3.2
EDIT .......................................................................................................................................... - 6 -
4.
SYSTEM SETUP....................................................................................................................... - 7 4.1
COM PORT SETUP ........................................................................................................................ - 7 -
4.2
TIMING MEASUREMENT ................................................................................................................ - 7 -
4.3
RESET WORKSTATION .................................................................................................................... - 7 -
5.
EXPERIMENT SETUP............................................................................................................... - 8 5.1
CELL& ELECTRODE SETUP .............................................................................................................. - 8 -
5.2
PSTAT/GSTAT SETUP ..................................................................................................................... - 9 -
5.3
WAITING BEFORE RUN ................................................................................................................. - 10 -
6.
STABLE POLARIZATION ........................................................................................................ - 10 6.1
OPEN CIRCUIT POTENTIAL ............................................................................................................ - 10 -
6.2
POTENTIOSTATIC ........................................................................................................................ - 11 -
6.3
GALVANOSTATIC ......................................................................................................................... - 13 -
6.4
POTENTIODYNAMIC .................................................................................................................... - 15 -
6.5
GALVANODYNAMIC ..................................................................................................................... - 17 -
7.
TRANSIENT POLARIZATION .................................................................................................. - 18 7.1
MULTI-POTENTIAL STEPS ............................................................................................................. - 18 -
7.2
MULTI-CURRENT STEPS ............................................................................................................... - 19 -
7.3
POTENTIAL STAIR-STEP ................................................................................................................ - 21 -
7.4
GALVANIC STAIR-STEP ................................................................................................................. - 22 -
8.
VOLTAMMETRY.................................................................................................................... - 23 8.1
LINEAR SWEEP VOLTAMMETRY ...................................................................................................... - 23 -
8.2
CYCLIC VOLTAMMETRY ................................................................................................................ - 24 -
8.3
STAIRCASE VOLTAMMETRY............................................................................................................ - 27 -
8.4
SQUARE WAVE VOLTAMMETRY ..................................................................................................... - 28 -
8.5
DIFFERENTIAL PULSE VOLTAMMETRY .............................................................................................. - 29 -
8.6
NORMAL PULSE VOLTAMMETRY .................................................................................................... - 31 -
8.7
DIFFERENTIAL NORMAL PULSE VOLTAMMETRY ................................................................................. - 32 -
8.8
A.C. VOLTAMMETRY ................................................................................................................... - 34 -
8.9
2ND HARMONIC A.C. VOLTAMMETRY ............................................................................................ - 35 -
9.
CHRONO TECHNIQUES ......................................................................................................... - 37 9.1
CHRONOPOTENTIOMETRY ............................................................................................................ - 37 -
9.2
CHRONOAMPEROMETRY .............................................................................................................. - 38 -
9.3
CHRONOCOULOMETRY ................................................................................................................ - 40 -
10.
STRIPPING VOLTAMMETRY .................................................................................................. - 41 -
10.1
POTENTIOMETRIC STRIPPING ................................................................................................... - 41 -
10.2
LINEAR STRIPPING ................................................................................................................. - 43 -
10.3
STAIRCASE STRIPPING ............................................................................................................. - 44 -
10.4
SQUARE-WAVE STRIPPING ....................................................................................................... - 46 -
11.
BI-POTENTIOSTAT ................................................................................................................ - 48 -
11.1
HYDROGEN DIFFUSION MEASUREMENTS..................................................................................... - 48 -
11.2
ROTATING DISK ELECTRODE (RDE)............................................................................................ - 51 -
12.
IMPEDANCE ......................................................................................................................... - 54 -
12.1
EIS VS FREQUENCY ................................................................................................................ - 54 -
12.2
EIS VS TIME ......................................................................................................................... - 58 -
12.3
EIS VS POTENTIAL.................................................................................................................. - 60 -
13.
CHARGING/DISCHARGING ................................................................................................... - 62 -
13.1
BATTERY CHARGING/DISCHARGING........................................................................................... - 62 -
13.2
GALVANNOSTATIC CHARGING/DISCHARGING ............................................................................... - 64 -
14.
MISC.TECHNIQUES ............................................................................................................... - 65 -
14.1
ELECTROCHEMICAL NOISE ....................................................................................................... - 65 -
14.2
DATE LOGGER ....................................................................................................................... - 66 -
14.3
ELECTROCHEMICAL STRIPPING/DEPOSITION................................................................................ - 67 -
15.
DATA VIEW .......................................................................................................................... - 69 -
15.1
CV DATA VIEW ..................................................................................................................... - 69 -
15.2
EIS DATA VIEW ..................................................................................................................... - 71 -
16.
DATE ANALYSIS .................................................................................................................... - 74 -
16.1
CORSHOW DATE ANALYSIS....................................................................................................... - 74 -
16.2
CORROSION RATE CALCULATION ............................................................................................... - 76 -
17.
CONTACT US ........................................................................................................................ - 77 -
User’s Manual
Part 1 CS Electrochemical Workstation
1. Introduction
CorrTest electrochemical suite consists
of a CS series electrochemical workstation
(potentiostat /galvanostat) and a set of
Corrtest® software. CS workstations are
dedicated to the cutting-edge research areas,
from batteries, electroplating, electrolysis,
electroanalysis, corrosion, to the synthesis of
nanomaterial, etc.
1.1 Hardware Specifications
Potential control range: ±10V
Current control range: ±2.0A
Potential control accuracy: 0.1%× full range±1mV
Current control accuracy: 0.1%× full range
Potential resolution: 10μV (>100Hz), 3μV (<10Hz)
Current sensitivity: 10pA
Rise time: <1μs (<10mA), <10μs (<2A)
Reference electrode input impedance: >1012Ω||20pF
Current range: 2A~ 200nA, 8 ranges
Compliance voltage: ±21V
Maximum current output: 2.0A
CV and LSV scan rate: 0.01mV~ 10,000V/s
CA and CC pulse width: 0.0001~ 65,000s
Current increment during scan: [email protected]/mS
Potential increment during scan: [email protected]/ms
SWV frequency: 0.001~100K Hz
DPV and NPV pulse width: 0.0001~1000s
AD data acquisition: [email protected] Hz,[email protected] Hz
DA Resolution: 16bit, Setup time: 1μs
Minimum potential increment in CV: 0.075mV
IMP frequency: 10μ Hz~ 115K Hz
Low-pass filters: Covering 8-decade
Potential and current range switch: Automatic
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1.2 Electrochemical Signal generator
Waveform generator
Frequency range: 10μ Hz~ 115K Hz
AC amplitude: 0~ 2,500mV
DC Bias: -10~ +10V
Output impedance: 50Ω
Waveform: Sine wave, triangular wave and Sine wave
Wave distortion: <1%
Scanning mode: Logarithmic/linear, increase/decrease
Signal analyzer:
Integral time: minimum: 10ms or the longest time of a cycle
Maximum: 106 cycles or 105s
Measurement delay: 0~ 105s
DC offset compensation:
Potential automatic compensation range: -10V~ +10V
Current compensation range: -1A~ +1A
Bandwidth: 8-decade Frequency range, Automatic and manual setting
1.3 Front Panel
The front panel of CS series instrument is shown in Figure 1-1.
Fig.1-1. Front panel of CS Electrochemical Workstation
Electrode Cable: The electrode cable provides a means for connecting an electrode to
the electrochemical workstation. The cell cable is described below for more details:
Green – Working electrode (WE) lead. This lead connects to the electrode of interest
at which the desired reactions will occur. The electrical signal is measured through WE
lead.
Red – Counter electrode (CE) lead. This lead connects to the electrode opposite the
WE and controls the power output of the instrument.
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Yellow – Reference electrode (RE) lead. This lead connects to the reference electrode,
a component of the differential amplifier that measures/controls the potential between
itself and the sense electrode.
Black – Ground lead. The use of this lead depends on the application fields. It is
mainly used to supply a ground point on a Faraday shield for the experimental cell, and
can also be used in some open circuit experiments to form a zero-resistance ammeter
(ZRA).
1.4 Potentiostatic mode
The mode of a CS instrument is a computerized general-purpose
potentiostat/galvanostat. The Figure below shows the electric schematic diagram of the
instrument.
Fig.1-2. Schematic diagram of CS instrument.
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Part 2 CorrTest® Software
2. Introduction
CorrTest® software shipped with the CS electrochemical workstation is an easy-touse, flexible, and versatile electrochemical tool and can be applied in many research fields
from corrosion, voltammetry, electroanalysis to battery test, etc. The main electrochemical
techniques include: Open circle potential (OCP), potentiostatic/galvanostatic polarization,
potentiodynamic/galvanodynamic polarization, Multi-potential/current, potential/current
stair-step, Chronopotentiometry (CP), Chronoamperometry (CA), Chronocoulometry
(CC), Cyclic Voltammetry (CV), Linear Sweep Voltammetry (LSV),Staircase Cyclic
Voltammetry (SCV), Square Wave Voltammetry (SWV), Differential Pulse Voltammetry
(DPV), Normal Pulse Voltammetry (NPV), Differential Normal Pulse Voltammetry
(DNPV), A.C. Voltammetry (ACV), Second Harmonic A.C. Voltammetry (SHACV),
Potentiostatic Stripping Volammetry, Linear Sweep Stripping Volammetry, Staircase
Stripping Volammetry, Square Stripping Volammetry, Differential Pulse Stripping
Volammetry, AC Impedance, Battery Test, Electrochemical Noise, etc.
CorrTest® software is also equipped with powerful corrosion analysis module, it can
calculate the corrosion rate of the material by linear polarization and weak polarization;
as well as the polarization resistance (Rp), Tafel slope (ba, bc), and corrosion current density
(icorr) through the non-linear fitting of Tafel curves. In addition, via the inherent
electrochemical impedance spectroscopy (EIS) technique, it can measure the double layer
capacitance (Cdl) and the solution (concrete) resistance (Rs). Moreover, CorrTest® provides
as a dual-channel data logger for pH, temperature or some physical quantities records.
The software can be widely applied in the following areas:
(1) Electrochemical mechanism studies, qualitative / quantitative chemical analysis.
(2) General electrochemical preparation, including electro-synthesis, electrodeposition (electroplating) performance evaluation.
(3) Research functional and/or energy materials (batteries, super-capacitor, nanometer
material, biological sensors, etc).
(4) Evaluation of corrosion inhibitor, water stabilizer, coating and cathodic protection
efficiency, and measurement of hydrogen permeability.
(5) Electrochemical corrosion measurement of materials in a conductive medium,
such as water, concrete and soil.
2.1 System Requirements
(1) Operating System: Windows XP / Vista / 7/ 8.
(2) Communication between PC and instrument: USB or RS-232 serial port.
(3) Output device: any printer or plotter supported by Windows.
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2.2 Software Installation
(1) USB Driver Installation. For the first time the workstation connects to the host PC
and is powered on, Windows® will display a “Found New Hardware” message, and
require driver installation. Upon this request, insert the CD into the CD-ROM drive, and
then select “Automatic” to install the CP2102USBdriverWin×.exe file.
(2) In the CD folder, choose “CSW_x32.exe”, or “CSW_x64.exe” according to your
computer’s operating system. Double click on the setup file and follow the instructions to
complete installation.
(3) Open the software shortcut on the Desktop. When CorrTest is opened for the very
first time, a software interface similar to the following picture will appear:
Fig.2-1. Interface of CorrTest software for CS Electrochemical Workstation
3. Menu
There are keyboard shortcuts for experiment methods on the right, such as “F2” for
“Open Circuit Potential”. Either by clicking on the “Open Circuit Potential” or pressing
“F2” key can users open the OCP test dialog box.
There is a toolbar under the main menu, and it can achieve the same function as the
main menu, and there will be a text message alert when users hover the mouse over a
button.
Users can also right-click the mouse on the main window; it will pop up the
“Experiments” menu.
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The
button will be activated when a test is running. Users can click on it to stop
the testing process. This button will be grayed out when the test is finished.
3.1 File
The File menu offers the following commands:
3.1.1 Open
Open an existing data file, and it can be edited and renamed.
3.1.2 Close
Close an open file. If the file has been modified, CorrTest software will prompt you
to save the changes.
3.1.3 Save
Save an open file with the same name.
3.1.4 Save As
Save As saves the current File with a different name.
3.1.5 Print Setup
A dialog box to set the print format.
3.1.6 Print
Print experiment results by using a default template created and selected in Print Setup.
3.1.7 Exit
Close the software.
3.2 Edit
The Edit menu include the following functions:
3.2.1 Cut
Cut allows the user to select the desired data from a Data Cut window to the clipboard.
3.2.2 Copy
Copy allows the user to select the desired data from a Data Copy window and paste
into another program.
3.2.3 Paste
Paste allows the user to select the data and paste into another program.
3.2.4 Delete
Delete permits the permanent deletion of data.
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4. System Setup
4.1 Com Port Setup
The software will automatically search for the Com Port when the instrument is
connected to the PC’s USB port
4.2 Timing Measurement
Timing measurement mode is convenient for users to run unattended experiments.
4.3 Reset Workstation
Restore the default values of all parameters.
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5. Experiment Setup
5.1 Cell& Electrode Setup
In this diabox, users can set information about the working electrode and the
electrolytic cell.
These parameters are mainly used to calculate corrosion rate. After clicking the “OK”
button, all parameters will be saved in a registration file.
The Surface Area specifies the exposed surface area of the sample or electrode. This
parameter does not affect the measurements. It will be used by CorShow to calculate
current density and corrosion rate.
The Density, Equivalent Weight, and Stern-Geary Coefficient are saved in the file to
help calculate corrosion rates. The Equivalent Weight is the Relative Atomic Mass divided
by number of electrons transferred during a reaction. Take the reaction Fe→ Fe2+ for
example, Iron has an atomic mass of 55.847 and transfers 2 electrons so the Equivalent
Weight is 55.847/2=27.92. Equivalent Weight can also be interpreted as mass loss per
electron transferred. This definition is particularly helpful when using alloys. The values
are also used by the Polarization Resistance experiment to calculate corrosion rates.
The Reference electrode Type saves information on the reference electrode for later
use by CorrTest. This parameter is not used during measurements (CorrTest always
displays and stores the actual cell potential). Most common reference types are predefined.
If your reference electrode is not in the list, you can enter the “User Defined”. Once the
reference electrode type is selected, CorrTest will be able to translate the potential data
from one reference type to another.
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5.2 Pstat/Gstat Setup
The Current Range parameter selects a full-scale current range to be applied during
the experiments. Selecting “Auto” allows the instrument to select the current range based
on the measured current.
The Potential Range parameter selects a maximum cell potential which can be
applied and measured. Generally speaking, “Auto” is the best choice unless the signal
changes very fast. In this case, data points will be lost.
IR Compensation Correction refers to methods requiring compensation for
unwanted medium resistances in an electrochemical system. Without correction, these
unwanted resistances may distort data or make it impossible to perform the desired
experiments.
The resistance of the electrolyte between the working electrode and the reference
electrode is the most common cause of errors. Moreover, contact resistance and long
electrode leads can cause errors too.
The Feedback compensation method may be used to boost the cell potential to
compensate potential drops caused by the cell geometry and solution resistivity. Feedback
may only be used with a fixed (not “Auto”) Current Range.
Polarity Convention defines how positive and negative potentials and currents are
interpreted. When the potential polarity is set to (O2+), a more positive potential produces
a larger driving force for an anodic/oxidation reaction and a more negative potential
produces a cathodic/reduction reaction. When the potential polarity is set to (O2-), a more
negative potential produces a larger driving force for an anodic/oxidation reaction and a
more positive potential produces cathodic/reduction reaction.
If the Current polarity is set to (O2+), positive current is for an anodic/oxidation
reaction and negative current is for a cathodic/reduction reaction. When using (O2-),
positive current is for a cathodic/reduction reaction and negative current is for an
anodic/oxidation reaction.
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The Low Pass Filter can be used to reduce high frequency noise.
5.3 Waiting before run
When switching from the natural state to the polarization of potentiostat, it takes time
before starting to scan because the electrode itself is unstable in the beginning. This can
be adjusted according to the specific requirements of the system.
6. Stable Polarization
6.1 Open Circuit Potential
Experiment→Stable Polarization→Open Circuit Potential
This experiment aims at monitoring the Open Circuit Potential (or Free Corrosion
Potential) as a function of time. The experiment can be performed for a fixed duration or
until a particular potential is reached.
OCP (V) will display the actual open circuit potential of the cell (updated per second).
6.1.1 Data File
When the experiment is performed, the data will be saved in the file specified by
Filename. The Dir button can be used to display a list of all directories and files. This is
particularly useful if you forget the file names you have already used. However, before
CorrTest starts performing the first experiment in the Experiment List, you may be warned
if the file has already existed.
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User’s Manual
CorrTest will automatically append the suffix “.COR” to a data file if you do not enter
one. Therefore, if you specify tutor1, the file tutor1.cor will be used. In the same way, if
you specify tutor1.abc, the file tutor1.abc.cor will be used.
The Comments text is saved in the data file. The time, date, and all measurement
parameters are automatically saved in the data file so you don’t need to write these
information into the comment area.
6.1.2 Experiment
The Total Time determines the total length of the experiment.
6.1.3 Experiment Termination
If the Use E box is checked, the experiment will be automatically terminated as long
as the potential goes below the Potential (V) < value or above the Potential (V) > value.
6.1.4 Data Acquisition
The acquisition rate in Points/Second is specified by the Sampl Freq(Hz) value.
6.1.5 Axis Type
When the experiment is performed, the data will be displayed as specified by the Axis
Type. CorrView can be later used to display the data in other formats.
6.1.6 Pstat/Gstat
The Experiments | Setup Pstat/Gstat... menu item is usually used to configure the
Pstat/Gstat for all experiments in the experiment list. These parameters are applicable to
all experiments where the Default Settings are selected. (See Pstat/Gstat Setting)
6.1.7 Cell Setup
See Cell Setup 9.1.
The OK button exits the setup diabox, saves all the changes you have made, and runs
the experiment.
Cancel exits the setup diabox. Any changes made to the parameters will be lost.
Help accesses the on-line help information on the setup of this experiment.
6.2 Potentiostatic
Experiment→Stable Polarization→Potentiostatic
This experiment applies a constant potential and monitors the current as a function of
time. The experiment can be performed for a fixed duration or until a particular current is
reached. A Galvanic corrosion can be performed by setting the applied potential to zero
vs. Reference electrode.
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User’s Manual
OCP (V) will display the actual open circuit potential of the cell (updated per second).
6.2.1 Data File
When the experiment is performed, the data will be saved in the file specified by
Filename. The Dir button can be used to display a list of all directories and files. This is
particularly useful if you forget the file names you have already used. However, before
CorrTest begins performing the first experiment in the Experiment List, you may be
warned if the file has already existed.
CorrTest will automatically append the suffix ‘.COR’ to a data file if you do not enter
one. Therefore, if you specify tutor1, the file tutor1.cor will be used. In the same say, if
you specify tutor1.abc, the file tutor1.abc.cor will be used.
The Comments text is saved in the data file. The time, date, and all measurement
parameters are automatically saved in the data file so you don’t need to write these
information into the comment area.
6.2.2 Experiment Parameters
The Initial E specifies the potential applied during the experiment. A potential can be
specified in several ways. If ‘vs. Open Circuit’ is chosen, the specified potential will be
added to the open circuit potential of the cell. For example, 0.1 vs. Open Circuit Potential
means applying a potential of 0.1 Volts above the measured open circuit potential. ‘vs.
Reference’ is used to select an exact potential to be applied.
The Total Time determines the total length of the experiment.
6.2.3 Experiment Termination
If the Use I box is checked, the experiment will be automatically terminated as long
as the current goes below the Current (A) < value or above the Current (A) > value.
If the Use Q box is checked, the experiment will be automatically terminated as long
as the total charge (in Coulombs) goes below the Charge (C) < value or above the Charge
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(C) > value.
If the not enabled box is checked, the experiment will not be terminated until the total
time is reached.
6.2.4 Data Acquisition
If Sampl Freq(Hz) is chosen, the acquisition rate in Points/Second is specified.
6.2.5 Axis Type
When the experiment is performed, the data will be displayed as specified by the Axis
Type. CorrView can be later used to display the data in other formats.
6.2.6 Pstat/Gstat
The Experiments | Setup Pstat/Gstat... menu item is usually used to configure the
Pstat/Gstat for all experiments in the Experiment List. These settings are applicable to all
experiments where the Default Settings are selected.(See Pstat/Gstat Setting)
6.2.7 Cell Setting
See Cell Setting 9.1.
The OK button exits the setup diabox and saves all changes you may have made and
runs the experiment.
Cancel exits the setup diabox. Any changes you may have made to the parameters
will be lost.
Help accesses the on-line help information on the setting up of this experiment.
6.3
Galvanostatic
Experiment→Stable Polarization→Galvanostatic
A constant current is applied and the potential is monitored as a function of time. The
experiment can be performed for a fixed duration or until a particular potential is reached.
OCP (V) will display the actual open circuit potential of the cell (updated per second).
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6.3.1 Data File
When the experiment is performed, the data will be saved in the file specified by
Filename. The Dir button can be used to display a list of all directories and files. This is
particularly useful if you forget the file names you have already used. However, before
CorrTest begins performing the first experiment in the Experiment List, you will be
warned if the file has already existed
CorrTest will automatically append the suffix ‘.COR’ to data files if you do not enter
one. Therefore if you specify tutor1, the file tutor1.cor will be used. In the same way, if
you specify tutor1.abc the file tutor1.abc.cor will be used.
The Comments text is saved in the data file. The time, date, and all measurement
parameters are automatically saved in the data file so you don’t need to write these
information into the comment area.
6.3.2 Experiment
Applied Current specifies the amount of current applied during the experiment. This
is the total current applied, rather than the current density.
The Total Time determines the total length of the experiment.
6.3.3 Experiment Termination
When the Use E box is checked, the experiment will be automatically terminated if
the potential goes below the Potential (V) < value or above the Potential (V) > value.
When the Use Q box is checked, the experiment will be automatically terminated if
the total charge (in Coulombs) goes below the Charge (C) < value or above the Charge
(C) > value.
If the not enabled box is checked, the experiment is not terminated until the total time
is reached.
6.3.4 Data Acquisition
If Sampl Freq(Hz) is chosen, the acquisition rate in Points/Second is specified.
6.3.5 Axis Type
When the experiment is performed, the data will be displayed as specified by the Axis
Type. CorrView can be later used to display the data in other formats.
6.3.6 Pstat/Gstat
The Experiments | Setup Pstat/Gstat... menu item is usually used to configure the
Pstat/Gstat for all experiments in the experiment list. These settings are applicable to all
experiments where the Default Settings are selected.(See Pstat/Gstat Setting)
6.3.7 Cell Setting
See Cell Setting 9.1.
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The OK button exits the setup window, saves all changes you have made, and runs
the experiment.
Cancel exits the setup diabox. Any changes made to the parameters will be lost.
Help accesses the on-line help information on the setup of this experiment.
6.4 Potentiodynamic
Experiment→Stable Polarization→Potentiodynamic
A potential sweep between up to 4 separate potential setpoints is applied and the
current response is measured. The sweep will be terminated or the sweep’s direction will
be reversed if a particular current is reached. This can be configured to obtain either
Polarization Resistance or Tafel data.
OCP (V) will display the actual open circuit potential of the cell (updated per second).
6.4.1 Data File
When the experiment is performed, the data will be saved in the file specified by
Filename. The Dir button can be used to display a list of all directories and files. This is
particularly useful if you forget the file names you have already used. However, before
CorrTest begins performing the first experiment in the Experiment List, you will be
warned if the file has already existed.
CorrTest will automatically append the suffix ‘.COR’ to data files if you do not enter
one. Therefore if you specify tutor1, the file tutor1.cor will be used. In the same way, if
you specify tutor1.abc the file tutor1.abc.cor will be used.
The Comments text is saved in the data file. The time, date, and all measurement
parameters are automatically saved in the data file so you don’t need to write these
information into the comment area.
6.4.2 Scanning Parameters
Up to 4 separate potentials can be applied during the experiment. The experiment
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User’s Manual
starts at the Initial Potential, sweeps to Vertex #1, to Vertex #2, and then to the Final
Potential. Click on the “Used” boxes to turn on or turn off the Vertex #1 and Vertex #2
setpoints. If a Vertex’s “Used” box is not checked, that segment of the sweep will be
skipped. For example, if only Vertex #1 is checked the sweep Initial →Vertex #1→Final
is performed. If neither Vertex #1 nor Vertex #2 is checked, Initial → Final is performed.
A potential can be specified in several ways. If ‘vs. Open Circuit’ is chosen, the
specified potential is added to the open circuit potential of the cell. For example 0.1 V vs
Open Circuit means applying a potential of 0.1 Volts above the measured open circuit
potential. ‘vs. Reference’ is used to select an exact potential to be applied.
The Scan Rate determines how fast the potential is scanned between one potential and
another.
6.4.3 Experiment Termination
When the Term box is checked, the sweep will end if certain potential and current
conditions are met. When the Rev. is checked, if certain potential and current conditions
are met, the experiment will immediately start sweeping toward the Final Potential.
The Termination or Reversal will occur when the current is above the Current> or
below Current<. Either of these conditions must be met to trigger the Termination or
Reversal. Be aware that the Termination/Reversal conditions in the Potentiodynamic
experiment are quite different from those in the other types of experiments.
6.4.4 Data Acquisition
If Sampl Freq (Hz) is chosen, the acquisition rate in Points/Second is specified.
6.4.5 Axis Type
When the experiment is performed, the data will be displayed as specified by the Axis
Type. CorrView can be later used to display the data in other formats.
6.4.6 Pstat/Gstat
The Experiments | Setup Pstat/Gstat... menu item is usually used to configure the
Pstat/Gstat for all experiments in the experiment list. These settings are applicable to all
experiments where the Default Settings are selected.(See Pstat/Gstat Setting)
6.4.7 Cell Setting
See Cell Setting 9.1.
The OK button exits the setup diabox, saves all the changes you have made, and runs
the experiment.
Cancel exits the setup diabox. Any changes made to the parameters will be lost.
Help accesses the on-line help information on the setup of this experiment.
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6.5 Galvanodynamic
Experiment→Stable Polarization→Galvanodynamic
Corrosion technique that uses a single current scan or ramp programs from an initial
current to a final current, plotting the resulting potential vs. time. A typical use of this
technique is to measure the relative susceptibility to localized corrosion.
This experiment applies a current sweep between up to 4 separate setpoints. The
sweep can be terminated if a particular potential is reached.
OCP will display the actual open circuit potential of the cell (updated per second). If
the instrument is turned off, this value will display ‘Not Available’.
6.5.1 Data File
When the experiment is performed, the data will be saved in the file specified by Data
File. The Dir button can be used to display a list of all directories and files. This is
particularly useful if you forget the file names you have already used. However, before
CorrTest begins performing the first experiment in the Experiment List, you may be
warned if the file has already existed.
6.5.2 Galvanodynamic Parameters
Up to 4 separate currents can be applied during the experiment. The experiment starts
at the Initial Current, sweeps to Vertex i#1, to Vertex i #2, and then to the Final Current.
Click on the Used boxes to turn on or turn off the Vertex i #1 and Vertex i#2 setpoints. If
a Vertex’s Used box is not checked, that segment of the sweep will be skipped. For
example, if only Vertex i#1 is checked the sweep Initial→Vertex i#1→Final is performed.
If neither Vertex i#1 nor Vertex i #2 is checked, Initial→Final is performed.
6.5.3 Experiment Stop
When the Scan Rev. box is checked, the experiment will immediately start sweeping
toward the Final Current if certain potential conditions are met.
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When the Scan Stop box is checked, the sweep will end if certain potential conditions
occur.
Note: The Current values specify the total current applied, rather than the current
density.
The Scan Rate determines how fast the current is scanned between one current and
another.
6.5.4 Data Acquisition
If Sampl Freq(Hz) is chosen, the acquisition rate in Points/Second is specified.
6.5.5 Axis Type
When the experiment is performed, the data will be displayed as specified by the Axis
Type. CorrView can be later used to display the data in other formats.
6.5.6 Pstat/Gstat
The Experiments | Setup Pstat/Gstat... menu item is usually used to configure the
Pstat/Gstat for all experiments in the experiment list. These settings are applicable to all
experiments where the Default Settings are selected.(See Pstat/Gstat Setting)
6.5.7 Cell Setting
See Cell Setting 9.1.
7. Transient Polarization
7.1 Multi-Potential Steps
Experiment→Transient Polarization→Multi-Potential Steps
In the Multi-Potential Steps technique, twelve potential steps can be applied and
cycled. Current is recorded as a function of time.
OCP will display the actual open circuit potential of the cell (updated per second). If
the instrument is turned off, this value will display ‘Not Available’.
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7.1.1 Data File
When the experiment is performed, the data will be saved in the file specified by Data
File. The Dir button can be used to display a list of all directories and files. This is
particularly useful if you forget the file names you have already used. However, before
CorrTest begins performing the first experiment in the Experiment List, you may be
warned if the file has already existed.
7.1.2 Multi-Potential Steps Parameters
A potential sweep between up to 12 separate potential setpoints is applied and the
current response is measured.
The experiment starts at the Initial Potential, sweeps to Step 1E, to Step 2E, to Step
3E,…and Final E. If the step time box is filled with zero, this segment of the sweep Step
will be skipped.
A potential can be specified in several ways. If ‘vs. Open Circuit’ is chosen, the
specified potential is added to the open circuit potential of the cell. ‘vs. Reference’ is used
to select an exact potential to be applied.
No. of Cycles specifies how many times the potential is cycled between Initial E and
Final E.
The Time determines how long the potential will be held at each step.
7.1.3 Data Acquisition
If Sampl Freq(Hz) is chosen, the acquisition rate in Points/Second is specified.
7.1.4 Axis Type
When the experiment is performed, the data will be displayed as specified by the Axis
Type. CorrView can be later used to display the data in other formats.
7.1.5 Pstat/Gstat
The Experiments | Setup Pstat/Gstat... menu item is usually used to configure the
Pstat/Gstat for all experiments in the experiment list. These settings are applicable to all
experiments where the Default Settings are selected.(See Pstat/Gstat Setting)
7.1.6 Cell Setting
See Cell Setting 9.1.
7.2 Multi-Current Steps
Experiment→Transient Polarization→Multi-Current Steps
In the Multi-Current Steps technique, twelve Current steps can be applied and cycled.
Potential is recorded as a function of time.
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OCP will display the actual open circuit potential of the cell (updated per second). If
the instrument is turned off, this value will display 'Not Available'.
7.2.1 Data File
When the experiment is performed, the data will be saved in the file specified by Data
File. The Dir button can be used to display a list of all directories and files. This is
particularly useful if you forget the file names you have already used. However, before
CorrTest begins performing the first experiment in the Experiment List, you will be
warned if the file has already existed.
7.2.2 Multi-Current Steps Parameters
A current sweep between up to 12 separate current setpoints is applied and the
potential response is measured.
The experiment starts from the Initial Current, and sweeps to Step 1, to Step 2, to Step
3,… and Final i. If the step time box is filled with zero, this segment of the sweep will be
skipped.
No. of Cycles: specifies the cycles of the current sweep from the Initial i to the Final
i.
The Time determines how long the current will be held at each step.
7.2.3 Data Acquisition
If Sampl Freq.(Hz) is chosen, the acquisition rate is set as Points/Second.
7.2.4 Axis Type
When the experiment is performed, the data will be displayed as specified by the Axis
Type. CorrView can be later used to display the data in other formats.
7.2.5 Pstat/Gstat
The Experiments | Setup Pstat/Gstat... menu item is usually used to configure the
Pstat/Gstat for all experiments in the experiment list. These settings are applicable to all
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experiments where the Default Settings are selected.(See Pstat/Gstat Setting)
7.2.6 Cell Setting
See Cell Setting 9.1.
7.3 Potential Stair-Step
Experiment→Transient Polarization→Potential Stair-Step
OCP will display the actual open circuit potential of the cell (updated per second). If
the instrument is turned off, this value will display 'Not Available'.
7.3.1 Data File
When the experiment is performed, the data will be saved in the file specified by Data
File. The Dir button can be used to display a list of all directories and files. This is
particularly useful if you forget the file names you have already used. However, before
CorrTest begins performing the first experiment in the Experiment List, you will be
warned if the file has already existed.
7.3.2 Step Potential Parameters
A potential sweep between up to 3 separate potential setpoints is applied and the
current response is measured. Unlike the Potentiodynamic experiment, the potential will
be changed in discrete steps rather than a smooth sweep.
The experiment starts at the Initial Potential, sweeps to Step E1, and then to Step E2.
Click on the “Use” boxes to turn on and turn off Step E2 setpoints. If a Vertex’s “Use” box
is not checked, that segment of the sweep Step E2 will be skipped.
The Time determines how long the potential will be held at each step.
A potential can be specified in several ways. If ‘vs. Open Circuit’ is chosen, the
specified potential is added to the open circuit potential of the cell. ‘vs. Reference’ is used
to select an exact potential to be applied.
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7.3.3 Data Acquisition
If Sampl Freq(Hz) is chosen, the acquisition rate in Points/Second is specified.
7.3.4 Axis Type
When the experiment is performed, the data will be displayed as specified by the Axis
Type. CorrView can be later used to display the data in other formats.
7.3.5 Pstat/Gstat
The Experiments | Setup Pstat/Gstat... menu item is usually used to configure the
Pstat/Gstat for all experiments in the experiment list. These settings are applicable to all
experiments where the Default Settings are selected.(See Pstat/Gstat Setting)
7.3.6 Cell Setting
See Cell Setting 9.1.
7.4 Galvanic Stair-Step
Experiment→Transient Polarization→Galvanic Stair-Step
OCP will display the actual open circuit potential of the cell (updated per second). If
the instrument is turned off, this value will display 'Not Available'.
7.4.1 Data File
When the experiment is performed, the data will be saved in the file specified by Data
File. The Dir button can be used to display a list of all directories and files. This is
particularly useful if you forget the file names you have already used. However, before
CorrTest begins performing the first experiment in the Experiment List, you will be
warned if the file already exists.
7.4.2 Scan Parameters
A current sweep between up to 3 separate current setpoints is applied and the potential
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response is measured.
The experiment starts at the Initial Current, sweeps to Step i#1, and then to Step i#2.
Click on the “Use” boxes to turn on or turn off Step i #2 setpoints. If a Vertex’s “Use” box
is not checked, that segment of the sweep Step i #2 will be skipped.
The Time determines how long the current will be held at each step.
7.4.3 Data Acquisition
If Sampl Freq(Hz) is chosen, the acquisition rate in Points/Second is specified.
7.4.4 Axis Type
When the experiment is performed, the data will be displayed as specified by the Axis
Type. CorrView can be later used to display the data in other formats.
7.4.5 Pstat/Gstat
The Experiments | Setup Pstat/Gstat... menu item is usually used to configure the
Pstat/Gstat for all experiments in the experiment list. These settings are applicable to all
experiments where the Default Settings are selected.(See Pstat/Gstat Setting)
7.4.6 Cell Setting
See Cell Setting 9.1.
8. Voltammetry
8.1 Linear Sweep Voltammetry
Experiment→Voltammetry→Linear Sweep Voltammetry
A single voltage ramp programs from an initial potential to a final potential that
progresses at a defined scan rate. To keep the step size on an “analog-like” level, the
maximum scan rate should be 1000V/s. To control the number of points acquired, the data
acquisition should be separated from any particular point, and spread out over the entire
scan range to a maximum of 1000 points per scan.
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OCP will display the actual open circuit potential of the cell (updated per second). If
the instrument is turned off, this value will display ‘Not Available’.
8.1.1 Data File
When the experiment is performed, the data will be saved in the file specified by Data
File. The Dir button can be used to display a list of all directories and files. This is
particularly useful if you forget the file names you have already used. However, before
CorrTest begins performing the first experiment in the Experiment List, you will be
warned if the file has already existed.
8.1.2 Scan Parameters
Up to 2 separate potentials can be applied during the experiment. The experiment
starts at the Initial Potential, and then to the Final Potential.
A potential can be specified in several ways. If ‘vs. Open Circuit’ is chosen, the
specified potential is added to the open circuit potential of the cell. For example 0.1 V vs
Open Circuit means applying a potential of 0.1 Volts above the measured open circuit
potential. ‘vs. Reference’ is used to select an exact potential to be applied.
The Scan Rate determines how fast the potential is scanned between one potential and
another.
8.1.3 Data Acquisition
If Sampl Freq(Hz) is chosen, the acquisition rate in Points/Second is specified.
8.1.4 Axis Type
When the experiment is performed, the data will be displayed as specified by the Axis
Type. CorrView can be later used to display the data in other formats.
8.1.5 Pstat/Gstat
The Experiments | Setup Pstat/Gstat... menu item is usually used to configure the
Pstat/Gstat for all experiments in the experiment list. These settings are applicable to all
experiments where the Default Settings are selected.(See Pstat/Gstat Setting)
8.1.6 Cell Setting
See Cell Setting 9.1.
8.2 Cyclic Voltammetry
Experiment→Voltammetry→Cyclic Voltammetry
Cyclic Voltammetry is a technique devoted to the theoretical study of redox couples.
Cyclic Voltammetry is a particular LSV that performs a triangular-shaped scanning at the
working electrode. In this way, a redox couple in solution is exposed to an oxidation and
afterwards to a reduction.
The plot of a cyclic voltammetry consists on a closed curve: reversible redox couples
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show both cathodic and anodic peak, while irreversible redox systems show only one peak.
The following formulas can be useful to establish the standard potential of a reversible
redox couple and figure out the number of electrons involved in the discharge process:
28.25
E pa  E1/ 2 
n
Where Epa = anodic peak potential
28.25
E pc  E1 / 2 
n
Epc= cathodic peak potential.
56.5
E p  E pa  E PC 
n
A two-stage voltage ramp is programmed from an initial potential to a vertex potential,
and then from the first vertex potential to a second one at a defined scan rate. The scan can
be repeated for many times (cycles) between the two vertex potentials. To keep the step
size on an “analog-like” level, the maximum scan rate should be10000V/s. To control the
number of points acquired, the data acquisition should be separated from any particular
points, and spread out over the entire scan range to a maximum of 1000 points per cycle.
This experiment applies a potential sweep between up to 4 separate potential setpoints.
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If only 2 setpoints are used, multiple cycles will be performed.
OCP will display the actual open circuit potential of the cell (updated per second). If
the instrument is turned off, this value will display ‘Not Available’.
8.2.1 Data File
When the experiment is performed, the data will be saved in the file specified by Data
File. The Dir button can be used to display a list of all directories and files. This is
particularly useful in case you forget the file name you have already used. However, before
CorrTest begins performing the first experiment in the Experiment List, you will be
warned if the file has already existed.
8.2.2 Scan Parameters
The potential may be swept between up to 4 separate setpoints in this experiment. The
experiment starts at the Initial Potential, sweeps to High E, to Low E, and then to the Final
Potential. Click on the “Use” boxes to turn on or turn off the Initial and Final setpoints. If
the Initial or Final setpoint is unchecked, this segment of the sweep will be skipped. For
example, if only the Initial is checked, the sweep Initial→High E→Low E will be
performed. If neither the Initial nor Final is checked, High E→Low E will be performed.
A potential can be specified in several ways. If ‘vs. Open Circuit’ is chosen, the
specified potential is added to the open circuit potential of the cell. For example, 0.1V vs.
Open Circuit means applying a potential of 0.1 Volts above the measured open circuit
potential. ‘vs. Reference’ is used to select an exact potential to be applied.
The Scan Rate selects how fast the potential is scanned between one potential and
another.
No. of Cycles specifies how many times potentials are cycled between High E and
Low E.
8.2.3 Data Acquisition
If Sampl Freq(Hz) is chosen, the acquisition rate in Points/Second is specified.
8.2.4 Axis Type:
When the experiment is performed, the data will be displayed as specified by the Axis
Type. CorrView can be later used to display the data in other formats.
8.2.5 Pstat/Gstat
The Experiments | Setup Pstat/Gstat... menu item is usually used to configure the
Pstat/Gstat for all experiments in the experiment list. These settings are applicable to all
experiments where the Default Settings are selected. (See Pstat/Gstat Setting)
8.2.6 Cell Setting
See Cell Setting 9.1.
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0.0003
0.0002
I (Amps/cm2)
0.0001
0
-0.0001
-0.0002
-0.0003
-0.5
0
0.5
1.0
1.5
E (Volts)
Figure 2-1. CV of Pt electrode in 1M H2SO4
8.3 Staircase Voltammetry
Experiment→Voltammetry→Staircase Voltammetry
In Staircase Voltammetry (SCV), the potential is incremented from Initial E toward
Final E, and it may be scanned back. Current is sampled after every potential increment
and recorded as a function of potential.
OCP will display the actual open circuit potential of the cell (updated per second). If
the instrument is turned off, this value will display ‘Not Available’.
8.3.1 Data File
When the experiment is performed, the data will be saved in the file specified by Data
File. The Dir button can be used to display a list of all directories and files. This is
particularly useful in case you forget the file names you have already used. However,
before CorrTest begins performing the first experiment in the Experiment List, you will
be warned if the file already exists.
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8.3.2 Scan Parameters
Init E and Final E should be at least 0.01 V apart. ‘vs. Referenc’' is used to select an
exact potential.
Incr E is the increment potential of each pulse; it can be chosen from 0.001 V to 0.05V.
Step Period can be chosen from 0.01 s to 50 s.
No. of Cycles specifies how many times potential are cycled between Initial E and
Final E.
8.3.3 Data Acquisition
If Sampl Freq (Hz) is chosen, the acquisition rate in Points/Second is specified.
8.3.4 Axis Type
When the experiment is performed, the data will be displayed as specified by the Axis
Type. CorrView can be later used to display the data in other formats.
8.3.5 Pstat/Gstat
The Experiments | Setup Pstat/Gstat... menu item is usually used to configure the
Pstat/Gstat for all experiments in the experiment list. These settings are applicable to all
experiments where the Default Settings are selected.(See Pstat/Gstat Setting)
8.3.6 Cell Setting
See Cell Setting 9.1.
8.4 Square Wave Voltammetry
Experiment→Voltammetry→Square Wave Voltammetry
The potentiostat applies a series of forward and reverse pulses (both equal in duration,
and defined as a frequency) superimposed on a linear staircase scan. The resulting currents
can be subtracted from one another to plot the difference current, which is helpful for
improving the sensitivity of analytical measurements. Technique is also referred to as SWV.
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OCP will display the actual open circuit potential of the cell (updated per second). If
the instrument is turned off, this value will display ‘Not Available’.
8.4.1 Data File
When the experiment is performed, the data will be saved in the file specified by Data
File. The Dir button can be used to display a list of all directories and files. This is
particularly useful if you forget the file names you have already used. However, before
CorrTest begins performing the first experiment in the Experiment List, you will be
warned if the file has already existed.
8.4.2 Scan Parameters
In Square Wave Voltammetry (SWV), the base potential is incremented from Init E
towards Final E. A square wave potential is superimposed onto the base potential, which
increments after each cycle of the square wave. Current is sampled at the end of the
forward and reverse steps and recorded as a function of the base potential. During the
experiment, only the difference between the two current samples is displayed. After the
experiment, the forward and reverse currents will also be available for display.
Init E and Final E should be at least 0.01 V apart. ‘vs. Reference’ is used to select an
exact potential to be applied.
Incr E is the increment potential of each pulse; it can be chosen from 0.001 V to 0.05
V.
Amplitude can be chosen from 0.001 V to 0.5 V.
Frequency can be chosen from 1Hz to 100000 Hz.
8.4.3 Data Acquisition
If Sampl Freq(Hz) is chosen, the acquisition rate in Points/Second is specified.
8.4.4 Axis Type
When the experiment is performed, the data will be displayed as specified by the Axis
Type. CorrView can be later used to display the data in other formats.
8.4.5 Pstat/Gstat
The Experiments | Setup Pstat/Gstat... menu item is usually used to configure the
Pstat/Gstat for all experiments in the experiment list. These settings are applicable to all
experiments where the Default Settings are selected. (See Pstat/Gstat Setting)
8.4.6 Cell Setting
See Cell Setting 9.1.
8.5 Differential Pulse Voltammetry
Experiment→Voltammetry→Differential Pulse Voltammetry
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The potentiostat applies a series of forward and reverse pulses (defined as a forward
pulse and a reverse step) superimposed on a linear staircase scan. The resulting currents
can be subtracted from one another to plot the difference current, which is helpful for
improving the sensitivity of analytical measurements. Technique is also referred to as DPV.
OCP will display the actual open circuit potential of the cell (updated per second). If
the instrument is turned off, this value will display ‘Not Available’.
8.5.1 Data File
When the experiment is performed, the data will be saved in the file specified by Data
File. The Dir button can be used to display a list of all directories and files. This is
particularly useful in case you forget the file names you have already used. However,
before CorrTest begins performing the first experiment in the Experiment List, you will
be warned if the file has already existed.
8.5.2 Scan Parameters
In Differential Pulse Voltammetry (DPV), the base potential is incremented from Init
E toward Final E. A potential pulse is applied. Current is sampled before and at the end of
the potential pulse. The difference between these two current samples is recorded as a
function of potential.
Init E and Final E should be at least 0.01 V apart.
A potential can be specified in several ways. If 'vs. Open Circuit' is chosen, the
specified potential is added to the open circuit potential of the cell. ‘vs. Reference’ is used
to select an exact potential.
Incr E is the increment potential of each pulse; it can be chosen from 0.001 V to 0.05
V.
Amplitude can be chosen from 0.001 V to 0.5 V.
Pulse Width can be chosen from 0.001 s to 10 s.
Pulse Period can be chosen from 0.01 s to 50 s.
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8.5.3 Data Acquisition
If Sampl Freq(Hz) is chosen, the acquisition rate in Points/Second is specified.
8.5.4 Axis Type
When the experiment is performed, the data will be displayed as specified by the Axis
Type. CorrView can be later used to display the data in any of the other formats.
8.5.5 Pstat/Gstat
The Experiments | Setup Pstat/Gstat... menu item is usually used to configure the
Pstat/Gstat for all experiments in the experiment list. These settings are applicable to all
experiments where the Default Settings are selected.(See Pstat/Gstat Setting)
8.5.6 Cell Setting
See Cell Setting 9.1.
8.6 Normal Pulse Voltammetry
Experiment→Voltammetry→Normal Pulse Voltammetry
The potentiostat applies a series of potential pulses from a constant baseline equal to
the initial potential, each pulse increasing by a defined increment (step height) to a final
potential. The resulting currents can be subtracted from one another to plot the difference
current, which is useful for improving the sensitivity of analytical measurements.
Technique is also referred to as NPV.
OCP will display the actual open circuit potential of the cell (updated per second). If
the instrument is turned off, this value will display ‘Not Available’.
8.6.1 Data File
When the experiment is performed, the data will be saved in the file specified by Data
File. The Dir button can be used to display a list of all directories and files. This is
particularly useful in case you forget the file names you have already used. However,
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before CorrTest begins performing the first experiment in the Experiment List, you will
be warned if the file has already existed.
8.6.2 Scan Parameters
In Normal Pulse Voltammetry (NPV), the base potential is held at Init E, and a
sequence of potential pulses with increasing amplitude is applied. The current at the end
of each potential pulse is sampled and recorded as a function of the pulse potential.
Init E and Final E should be at least 0.01 V apart. 'vs. Reference' is used to select an
exact potential to be applied.
Incr E is the increment potential of each pulse; it can be chosen from 0.001 V to 0.05
V.
Pulse Width can be chosen from 0.001 s to 10 s.
Pulse Period can be chosen from 0.01 s to 50 s.
8.6.3 Data Acquisition
If Sampl Freq(Hz) is chosen, the acquisition rate in Points/Second is specified.
8.6.4 Axis Type
When the experiment is performed, the data will be displayed as specified by the Axis
Type. CorrView can be later used to display the data in any of the other formats.
8.6.5 Pstat/Gstat
The Experiments | Setup Pstat/Gstat... menu item is usually used to configure the
Pstat/Gstat for all experiments in the experiment list. These settings are applicable to all
experiments where the Default Settings are selected.(See Pstat/Gstat Setting)
8.6.6 Cell Setting
See Cell Setting 9.1.
8.7 Differential Normal Pulse Voltammetry
Experiment→Voltammetry→Differential Normal Pulse Voltammetry
This is a hybrid of differential pulse and normal pulse voltammetry. Similar to the
normal pulse method, in this case a pulse will be superimposed on a base potential. On top
of this pulse a modulation step with definable amplitude and duration is applied. The
current just before and at the end of the modulation step will be measured and the
difference will be stored. In this manner, the advantages of normal pulse (short electrolysis
time) are combined with those of differential pulse (pronounced faraday currents).
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OCP will display the actual open circuit potential of the cell (updated per second). If
the instrument is turned off, this value will display ‘Not Available’.
8.7.1 Data File
When the experiment is performed, the data will be saved in the file specified by Data
File. The Dir button can be used to display a list of all directories and files. This is
particularly useful if you forget the file names you have already used. However, before
CorrTest begins performing the first experiment in the Experiment List, you will be
warned if the file has already existed.
8.7.2 Scan Parameters
In Differential Pulse Voltammetry (DPV), the base potential is incremented from Init
E toward Final E. A potential pulse is applied. Current is sampled before the potential
pulse and at the end of the pulse. The difference between these two current samples is
recorded as a function of potential.
Init E and Final E should be at least 0.01 V apart. ‘vs. Reference’ is used to select an
exact potential to be applied.
Incr E is the increment potential of each pulse; it can be chosen from 0.001 V to 0.05V.
Amplitude can be chosen from 0.001 V to 0.5 V.
1st Pulse Width can be chosen from 0.001 s to 10 s.
2nd Pulse Width can be chosen from 0.001 s to 10 s.
Pulse Period can be chosen from 0.05 s to 50 s.
8.7.3 Data Acquisition
If Sampl Freq(Hz) is chosen, the acquisition rate in Points/Second is specified.
8.7.4 Axis Type
When the experiment is performed, the data will be displayed as specified by the Axis
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Type. CorrView can be later used to display the data in other formats.
8.7.5 Pstat/Gstat
The Experiments | Setup Pstat/Gstat... menu item is usually used to configure the
Pstat/Gstat for all experiments in the experiment list. These settings are applicable to all
experiments where the Default Settings are selected.(See Pstat/Gstat Setting)
8.7.6 Cell Setting
See Cell Setting 9.1.
8.8 A.C. Voltammetry
Experiment→Voltammetry→A.C. Voltammetry
In A.C. Voltammetry, the base potential is incremented from Init E to Final E, and a
sequential sine waveform is superimposed. Current is sampled when the AC signal is
applied, and it is analyzed by using a software lock-in amplifier. During the experiment,
only the absolute AC current is displayed. After the experiment, the phase-selective
current at any phase angle will also be available for display.
OCP will display the actual open circuit potential of the cell (updated per second). If
the instrument is turned off, this value will display ‘Not Available’.
8.8.1 Data File
When the experiment is performed, the data will be saved in the file specified by Data
File. The Dir button can be used to display a list of all directories and files. This is
particularly useful if you forget the file names you have already used. However, before
CorrTest begins performing the first experiment in the Experiment List, you may be
warned if the file has already existed.
8.8.2 Scan Parameters
Init E and Final E should be at least 0.01 V apart.
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Incr E is the increment potential of each pulse; it can be chosen from 0.001 V to 0.05
V.
Amplitude can be chosen from 0.001 V to 0.5 V.
When the AC frequency is 2 Hz or lower, the Sample Period parameter should be at
least 2 seconds.
Bias DC Current, check off or on, enables DC current bias during run.
8.8.3 Data Acquisition
If Sampl Freq(Hz) is chosen, the acquisition rate in Points/Second is specified.
8.8.4 Axis Type
When the experiment is performed, the data will be displayed as specified by the Axis
Type. CorrView can be later used to display the data in other formats.
8.8.5 Pstat/Gstat
The Experiments | Setup Pstat/Gstat... menu item is usually used to configure the
Pstat/Gstat for all experiments in the experiment list. These settings are applicable to all
experiments where the Default Settings are selected.(See Pstat/Gstat Setting)
8.8.6 Cell Setting
See Cell Setting 9.1.
8.9 2nd Harmonic A.C. Voltammetry
Experiment→Voltammetry→2nd Harmonic A.C. Voltammetry
In Second Harmonic AC Voltammetry, the base potential is incremented from Init E
toward Final E, and a sequential sine waveform is superimposed. Current is sampled when
the AC signal is applied, and a second harmonic component is analyzed by using a
software lock-in amplifier. During the experiment, only the absolute second harmonic AC
current is displayed. After the experiment, the phase-selective second harmonic current at
any phase angle will also be available for display.
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OCP will display the actual open circuit potential of the cell (updated per second). If
the instrument is turned off, this value will display ‘Not Available’.
8.9.1 Data File
When the experiment is performed, the data will be saved in the file specified by Data
File. The Dir button can be used to display a list of all directories and files. This is
particularly useful if you forget the file names you have already used. However, before
CorrTest begins performing the first experiment in the Experiment List, you will be
warned if the file has already existed.
8.9.2 Scan Parameters
Init E and Final E should be at least 0.01 V apart.
Incr E is the increment potential of each pulse; it can be chosen from 0.001 V to 0.05
V.
Amplitude can be chosen from 0.001 V to 0.5 V.
When the AC frequency is 2 Hz or lower, the Sample Period parameter should be at
least 2 seconds.
Bias DC Current, check off or on, enables DC current bias during run.
8.9.3 Data Acquisition
If Sampl Freq(Hz) is chosen, the acquisition rate in Points/Second is specified.
8.9.4 Axis Type
When the experiment is performed, the data will be displayed as specified by the Axis
Type. CorrView can be later used to display the data in other formats.
8.9.5 Pstat/Gstat
The Experiments | Setup Pstat/Gstat... menu item is usually used to configure the
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Pstat/Gstat for all experiments in the experiment list. These settings are applicable to all
experiments where the Default Settings are selected.(See Pstat/Gstat Setting)
8.9.6 Cell Setting
See Cell Setting 9.1.
9. Chrono Techniques
9.1 Chronopotentiometry
Experiment→Chrono Techniques→Chronopotentiometry
A fast-rising current pulse is enforced on the working-sense electrode of an
electrochemical cell and the potential of this electrode is measured against a reference
electrode as a function of time. Technique is also referred to as CP.
For a Two-Step Chronopotentiometry experiment, two CP actions are inserted into the
same sequence, each set at the desired current step, and with the cell remaining ON at the
end of the first step.
OCP will display the actual open circuit potential of the cell (updated per second). If
the instrument is turned off, this value will display ‘Not Available’.
9.1.1 Data File
When the experiment is performed, the data will be saved in the file specified by Data
File. The Dir button can be used to display a list of all directories and files. This is
particularly useful if you forget the file names you have already used. However, before
CorrTest begins performing the first experiment in the Experiment List, you will be
warned if the file has already existed.
9.1.2 Scan Parameters
Cathodic and anodic currents correspond to reduction and oxidation respectively. The
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time can be different for switching between cathodic and anodic. However, the Initial
Polarity parameter specifies the initial current polarity.
Number of Segments specifies how many times the current is cycled between
Cathodic and anodic currents. When the number of current polarity switches (Segments)
is reached, the experiment stops.
9.1.3 Current Switching Polarity
When the Low E limit is reached during reduction, the current polarity will
automatically be switched to be anodic. Similarly, when the High E limit is reached during
oxidation, current will automatically be switched to be cathodic.
The current switching polarity can be checked when either the specified potential or
the specified time has been reached. If the limiting potential is reached, the current polarity
will still be reversed in order to protect the electrode.
9.1.4 Data Acquisition
If Sampl Freq(Hz) is chosen, the acquisition rate in Points/Second is specified.
9.1.5 Axis Type
When the experiment is performed, the data will be displayed as specified by the Axis
Type. CorrView can be later used to display the data in other formats.
9.1.6 Pstat/Gstat
The Experiments | Setup Pstat/Gstat... menu item is usually used to configure the
Pstat/Gstat for all experiments in the experiment list. These settings are applicable to all
experiments where the Default Settings are selected.(See Pstat/Gstat Setting)
9.1.7 Cell Setting
See Cell Setting 9.1.
9.2 Chronoamperometry
Experiment→Chrono Techniques→Chronoamperometry
A fast-rising potential pulse is enforced on the working-sense electrode of an
electrochemical cell; the current flowing through this electrode is measured as a function
of time. Technique is also referred to as CA.
For a Two-Step Chronoamperometry experiment, either insert two CA actions into the
same sequence (each set at the desired Potential step and with the cell remaining ON at
the end of the first step) or preferably, run a two-step Fast Potential Pulse action if that is
available.
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OCP will display the actual open circuit potential of the cell (updated per second). If
the instrument is turned off, this value will display ‘Not Available’.
9.2.1 Data File
When the experiment is performed, the data will be saved in the file specified by Data
File. The Dir button can be used to display a list of all directories and files. This is
particularly useful if you forget the file names you have already used. However, before
CorrTest begins performing the first experiment in the Experiment List, you may be
warned if the file has already existed.
9.2.2 Scan Parameters
The experiment starts at the Initial Potential, sweeps to High E, and then to Low E. A
potential can be specified in several ways. If ‘vs. Open Circuit’ is chosen, the specified
potential is added to the open circuit potential of the cell. ‘vs. Reference’ is used to select
an exact potential to be applied.
Pulse Width specifies how long the potential is sustaining.
Number of Steps specifies how many potential cycles are formed between High E and
Low E.
9.2.3 Data Acquisition
If Sampl Freq(Hz) is chosen, the acquisition rate in Points/Second is specified.
9.2.4 Axis Type
When the experiment is performed, the data will be displayed as specified by the Axis
Type. CorrView can be later used to display the data in other formats.
9.2.5 Pstat/Gstat
The Experiments | Setup Pstat/Gstat... menu item is usually used to configure the
Pstat/Gstat for all experiments in the experiment list. These settings are applicable to all
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experiments where the Default Settings are selected.(See Pstat/Gstat Setting).
9.2.6 Cell Setting
See Cell Setting 9.1.
9.3 Chronocoulometry
Experiment→Chrono Techniques→Chronocoulometry
A fast-rising potential pulse is enforced on the working-sense electrode of an
electrochemical cell. The current flowing through this electrode is measured and
integrated, reporting coulombs as a function of time. Technique is also referred to as CC.
For bulk electrolysis measurements, a Pre-Electrolysis parameter is provided to
electrolyze and subtract out solvent background currents, with the sample of interest added
after the Pre-Elect (s) stage to measure the total charge associated with the sample, minus
the background current contributions.
OCP will display the actual open circuit potential of the cell (updated per second). If
the instrument is turned off, this value will display ‘Not Available’.
9.3.1 Data File
When the experiment is performed, the data will be saved in the file specified by Data
File. The Dir button can be used to display a list of all directories and files. This is
particularly useful if you forget the file names you have already used. However, before
CorrTest begins performing the first experiment in the Experiment List, you may be
warned if the file has already existed.
9.3.2 Scan Parameters
The potential may be swept between up to 2 separate setpoints in this experiment. The
experiment starts at the Initial Potential, and then to the Final Potential. A potential can be
specified in several ways. If ‘vs. Open Circuit’ is chosen, the specified potential is added
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to the open circuit potential of the cell. ‘vs. Reference’ is used to select an exact potential
to be applied.
Pulse Width specifies how long the potential is sustaining.
Number of Steps specifies how many times the potential is cycled between Initial
Potential and Final Potential.
9.3.3 Data Acquisition
If Sampl Freq(Hz) is chosen, the acquisition rate in Points/Second is specified.
9.3.4 Axis Type
When the experiment is performed, the data will be displayed as specified by the Axis
Type. CorrView can be later used to display the data in other formats.
9.3.5 Pstat/Gstat
The Experiments | Setup Pstat/Gstat... menu item is usually used to configure the
Pstat/Gstat for all experiments in the experiment list. These settings are applicable to all
experiments where the Default Settings are selected.(See Pstat/Gstat Setting)
9.3.6 Cell Setting
See Cell Setting 9.1.
10. Stripping Voltammetry
10.1 Potentiometric Stripping
Experiment→Stripping Voltammetry→Potentiometric Stripping
In stripping voltammetry, the usual working electrode is a dropping (or a film)
mercury and the most common technique is the anodic stripping, meaning that a negative
potential is applied to the electrode and the cations are discharged as metallic atoms into
the mercury (amalgam). Successively, the metal atoms are oxidised again during an anodic
scanning of potential. During the scanning of the potential, the current is measured and
plotted, so the resulting voltammogram is a peak shaped graphic.
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Figure 2-2.Stripping voltammetry in a solution containing Pb2+, Cd2+, Cu2+.
OCP will display the actual open circuit potential of the cell (updated per second). If
the instrument is turned off, this value will display ‘'Not Available’'.
10.1.1 Data File
When the experiment is performed, the data will be saved in the file specified by Data
File. The Dir button can be used to display a list of all directories and files. This is
particularly useful if you forget the file names you have already used. However, before
CorrTest begins performing the first experiment in the Experiment List, you may be
warned if the file has already existed.
10.1.2 Deposition Parameters
Before the experiment, the surface of working electrode needs cleaning by this
conditioning step.
A constant potential deposition step is applied to accumulate species on the working
electrode surface. This potential can be specified to choose either ‘vs. Open Circuit’ or ‘vs.
Reference’.
The deposition time determines how long the potential will be held at this step. After
deposition, the experiment can be quiet for some time.
10.1.3 Potentiometric Stripping Parameters
After the constant potential deposition step is applied, the species accumulated on the
electrode surface are stripped out by applying a constant potential.
This stripping potential can be specified in several ways. If ‘vs. Open Circuit’ is
chosen, the specified potential is added to the open circuit potential of the cell. ‘vs.
Reference’ is used to select an exact potential.
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10.1.4 Data Acquisition
If Sampl Freq(Hz) is chosen, the acquisition rate in Points/Second is specified.
10.1.5 Axis Type:
When the experiment is performed, the data will be displayed as specified by the Axis
Type. CorrView can be later used to display the data in other formats.
10.1.6 Pstat/Gstat
The Experiments | Setup Pstat/Gstat... menu item is usually used to configure the
Pstat/Gstat for all experiments in the experiment list. These settings are applicable to all
experiments where the Default Settings are selected.(See Pstat/Gstat Setting)
10.1.7 Cell Setting
See Cell Setting 9.1.
10.2 Linear Stripping
Experiment→Stripping Voltammetry→Linear Stripping
OCP will display the actual open circuit potential of the cell (updated per second). If
the instrument is turned off, this value will display ‘Not Available’.
10.2.1 Data File
When the experiment is performed, the data will be saved in the file specified by Data
File. The Dir button can be used to display a list of all directories and files. This is
particularly useful if you forget the file names you have already used. However, before
CorrTest begins performing the first experiment in the Experiment List, you will be
warned if the file has already existed.
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10.2.2 Deposition Parameters
Before the experiment, the surface of working electrode needs cleaning by this
conditioning step.
A constant potential deposition step is applied to accumulate species on the working
electrode surface. This potential can be specified to choose either vs. ‘Open Circuit’ or ‘vs.
Reference’.
The deposition time determines how long the potential will be held at this step. After
deposition, the experiment can be quiet for some time.
10.2.3 Linear Stripping Parameters
In Linear Stripping, a constant potential deposition step is first applied. After that, the
species accumulated on the electrode surface are stripped out by applying a linear potential,
which is scanned from an initial potential to a final potential that progresses at a defined
scan rate.
A potential can be specified in several ways. If ‘vs. Open Circuit’ is chosen, the
specified potential is added to the open circuit potential of the cell. ‘vs. Reference’ is used
to select an exact potential.
10.2.4 Data Acquisition
If Sampl Freq (Hz) is chosen, the acquisition rate in Points/Second is specified.
10.2.5 Axis Type
When the experiment is performed, the data will be displayed as specified by the Axis
Type. CorrView can be later used to display the data in other formats.
10.2.6 Pstat/Gstat
The Experiments | Setup Pstat/Gstat... menu item is usually used to configure the
Pstat/Gstat for all experiments in the experiment list. These settings are applicable to all
experiments where the Default Settings are selected.(See Pstat/Gstat Setting)
10.2.7 Cell Setting
See Cell Setting 9.1.
10.3 Staircase Stripping
Experiment→Stripping Voltammetry→Staircase Stripping
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OCP will display the actual open circuit potential of the cell (updated per second). If
the instrument is turned off, this value will display ‘Not Available’.
10.3.1 Data File
When the experiment is performed, the data will be saved in the file specified by Data
File. The Dir button can be used to display a list of all directories and files. This is
particularly useful if you forget the file names you have already used. However, before
CorrTest begins performing the first experiment in the Experiment List, you will be
warned if the file has already existed.
10.3.2 Staircase Stripping Parameters
Before the experiment, the surface of working electrode needs cleaning by this
conditioning step.
A constant potential deposition step is applied to accumulate species on the working
electrode surface. This potential can be specified to choose either ‘vs. Open Circuit’ or ‘vs.
Reference’.
The deposition time determines how long the potential will be held at this step. After
deposition, the experiment can be quiet for some time.
In Staircase Stripping, a constant potential deposition step is applied. After that the
species accumulated on the electrode surface are stripped out by applying a staircase
potential, which is incremented from Initial E toward Final E that progresses at a defined
increment.
10.3.3 Data Acquisition
If Sampl Freq (Hz) is chosen, the acquisition rate in Points/Second is specified.
10.3.4 Axis Type
When the experiment is performed, the data will be displayed as specified by the Axis
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Type. CorrView can be later used to display the data in other formats.
10.3.5 Pstat/Gstat
The Experiments | Setup Pstat/Gstat... menu item is usually used to configure the
Pstat/Gstat for all experiments in the experiment list. These settings are applicable to all
experiments where the Default Settings are selected.(See Pstat/Gstat Setting)
10.3.6 Cell Setting
See Cell Setting 9.1.
10.4 Square-wave stripping
Experiment→Stripping Voltammetry→Square wave Stripping
The waveform can be viewed as a special case of that used for DPV, in which the
preelectrolysis period and the pulse are of equal duration, and the pulse is opposite from
the scan direction. However, the interpretation of results is facilitated by considering the
waveform as something consisting of a staircase scan, each tread of which is superimposed
by a symmetrical double pulse, one in the forward direction and the other in the reverse.
Over many cycles, the waveform is a bipolar square wave superimposed on the
staircase.This view gives rise to the name of the method.
OCP will display the actual open circuit potential of the cell (updated per second). If
the instrument is turned off, this value will display ‘Not Available’.
10.4.1 Data File
When the experiment is performed, the data will be saved in the file specified by Data
File. The Dir button can be used to display a list of all directories and files. Corrtest
automatically appends the suffix ‘.COR’ to data files. The Comments text is saved in the
data file. The time, date, and all measurement parameters are automatically saved in the
data file so you don’t need to write these information into the comment area.
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10.4.2 Deposition Parameters
Conditioning potential: Before deposition, the conditioning potential is applied on
working electrode in order to remove impurities, and automatically update working
electrode surface state.
Duration: It is a separate time value that specifies the length of time when that
conditioning potential is applied.
Deposition potential: Deposition potential is generally lower than the standard redox
potential by 0.3 ~ 0.5V. Metal ions which will be measured are easily reduced.
Deposition time: It is a separate time value that specifies the length of time when that
deposition potential is applied.
Quiet time: When stopping stirring, potential is not applied on the working electrode.
10.4.3 Square wave stripping Parameters
Initial potential: the minimum potential for dissolution process to begin.
Final potential: Final potential is generally higher than the oxidation potential of
analyte ions.
Increment potential: the incremental potential of each step.
Amplitude: square wave amplitude, half peak-to-peak.
Frequency: square wave pulse frequency.
A potential can be specified in several ways. If ‘vs. Open Circuit’ is chosen, the
specified potential is added to the open circuit potential of the cell. For example, 0.1V vs.
Open Circuit means applying a potential 0.1 Volts above the open circuit potential. ‘vs.
Reference’ is used to select an exact potential.
10.4.4 Data Acquisition
If Sampl Freq(Hz) is chosen, the acquisition rate in Points/Second is specified.
10.4.5 Axis Type
When the experiment is performed, the data will be displayed as specified by the Axis
Type. CorrView can be later used to display the data in other formats.
10.4.6 Pstat/Gstat
The Experiments | Setup Pstat/Gstat... menu item is usually used to configure the
Pstat/Gstat for all experiments in the experiment list. These settings are applicable to all
experiments where the Default Settings are selected.(See Pstat/Gstat Setting)
10.4.7 Cell Setting
See Cell Setting 9.1.
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11. Bi-Potentiostat
11.1 Hydrogen diffusion measurements
Experiment→Bi-Potentiostat→Hydrogen diffusion measurements
Hydrogen
permeation
measurements require a special set
of electrolytic cells where two
electrolytic cells (one for the
constant
current
charging
hydrogen, the other for hydrogen
current detection). In each
electrolytic cell there is an
independent set of reference
electrode and the auxiliary
electrode, sharing a common
working electrode. This working
electrode is composed of a
metallic thin plate clipped between the two electrolytic cells. (See the right Figure).
When hydrogen charging surface of the working electrode is impose with square wave
cathode current, by changing the hydrogen charging current via alternating, the atoms will
diffuse into the metal, and gradually arrive at the detection surface (i.e. opposite surface)
of the working electrode. By measuring the value of the hydroxide current and delay time,
users can calculated the hydrogen diffusion rate and the diffusion coefficient.
Users should connect the double electrolytic cell in the way as shown below, add
0.1mol / L of NaOH into the anode chamber ( on the right) , and link the anodic chamber
electrode cable onto the main unit of the front panel and cathode chamber electrode cable
onto the slave unit. Firstly set the anodic polarization potential of the potentiostat on main
unit to be 0.2V vs. Hg / HgO, start the polarization, the anode current will sharply decline
at the beginning, then slowly tends to retain a constant value, that is, anode residual current.
It is produced by hydrogen left inside the steel or some oxidated impurities in the diffusion
surface solution. When the residual current is lower than the setting value, users can add
experimental media (such as dilute Hydrochloric Acid) into the cathode chamber, and then
start galvanostatic polarization of the slave unit. The initial current is in the peak (See the
below figure), 10mA for instance. And on C-face of cathode chamber the hydrogen ions
will be reduced to hydrogen atoms, some of which will permeate into and across metallic
disk, reaching A-face of the anodic chamber. Upon potentiostatic anodic polarization on
the main unit, these hydrogen atoms will be oxidated and become ions, forming oxidation
currents.
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Figure 2-3. Connection diagram for Hydrogen diffusion coefficient test device
Figure 2-4. Hydrogen charging current curve under control of square wave
Due to diffusion rate limitation of the hydrogen atoms, there will be a current delay
on the hydrogen detection side, with the phenomenon that anode current gradually
increases with time (on the rising edge) or decreases (on the falling edge). According to
delay duration of the hydrogen detection current and the current value, users can figure
out the concentration of hydrogen in the metal as well as the diffusion rate, and further,
determine certain corrosion inhibitors’ effect on hydrogen permeation.
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11.1.1 Data File
When the experiment is performed, the data will be saved in the file specified by Data
File. The Dir button can be used to display a list of all directories and files. This is
particularly useful if you forget the file names you have already used. However, before
CorrTest begins performing the first experiment in the Experiment List, you will be
warned if the file has already existed.
11.1.2 Hydrogen ion reduction (Slave unit)
Users should set peak and trough current of the hydrogen charging current square
wave, as well as the corresponding duration. Hydrogen charging current can only flow to
the cathode so that hydrogen atoms become ions via reduction and diffuse through the
working electrode (metal disk in the center). Number of cycles of hydrogen charging
current is equal to the number of square wave.
11.1.3 Hydrogen ion oxidation (main unit)
Polarization potential (V) — in the electrolytic cell the hydrogen is applied to the
working end of the current detecting electrode polarization potential. Generally speaking,
this potential enables the working electrode (metal thin disk) to stay in anodic polarization.
That is to say, a positive polarization potential should be entered to allow hydrogen atoms
from the opposite side of the medal disk to be oxidated and turn into ions.
Oxidation of residual current —With the continuing of potentiostatic polarization,
residual hydrogen current in the metal will gradually reduce. When it is lower than the set
value, the software can be start galvanostatic polarization of hydrogen charging, and
hydrogen charging begins.
Upon the start of the measurement, firstly the main unit will open potentiostatic
polarization, so that the hydrogen atoms in the metal foil can sufficiently diffuse out onto
the oxidation surface and finish the process of oxidation. It takes a relatively long time.
According to ISO standards, generally speaking, only when the residual oxidation current
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is lower than 1 ~ 2μA/cm² (threshold value of residual current) can the users consider
hydrogen atoms in the metal foil being completely oxidized away. Once the oxidation
current is lower than the threshold, the slave unit will start the process of constant current
hydrogen charging. Hydrogen charging current varies between the peak and the trough
value. In general, 10~20 minutes later (based on the material and thickness of the metal),
the anode current detected by the main unit will gradually increase and eventually keep
stable, because hydrogen atoms diffuse out to the opposite side of the metal disk and are
oxidized to form anode current.
Polarization time — Users can specify the potentiostatic polarization time. They can
choose unit among “second”, “minute” and “hour.”
11.1.4 Data Acquisition
If Sampl Freq(Hz) is chosen, the acquisition rate in Points/Second is specified.
11.1.5 Axis Type
When the experiment is performed, the data will be displayed as specified by the Axis
Type. CorrView can be later used to display the data in other formats.
11.1.6 BiStat Config
For bipotentiostat users need to do settings for the main & slave units respectively.
Parameters of them can be the same or different. With buttons of “main unit”and “slave
unit”, users can set the current range switching, signal gain, low-pass filter switches,
digital smoothing, scan (polarization) delay time and so on. Please note real ground must
be chosen for earthing mode.
11.1.7 Cell Setting
See Cell Setting 9.1.
11.2 Rotating Disk Electrode (RDE)
Experiment→Bi-Potentiostat→Rotating disk electrode
Compared with the stationary electrode, rotating disk electrode has the following
advantages: stable concentration polarization; good stability of polarization curves;
capable of measuring relatively rapid electrochemical reactions. So polarization curves of
the rotating disk electrode have wide applications, especially in the aspects of calculating
diffusion coefficients, electron gains &losses in reactions, the concentration of reactants,
leveling effect of electroplating additives, and the electrode kinetic parameters, etc. With
the help of ring electrode, users can also detect reaction intermediates on the disk electrode.
DW is disk electrode (See left in the figure below), while RW is the ring electrode.
They are two separate concentric working electrodes. According to the experimental
requirements, DW and RW should be at different polarization potential so that
electrochemical product on DW can reach ring electrode for further oxidation-reduction
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reaction and be detected.
Disk and ring electrodes are connected to potentiostat with dual units. The main unit
is also called the main channel potentiostat, and the slave unit is also called the auxiliary
channel potentiostat whose function is to control the potential difference between DW and
RW.
Figure 2-5. Rotating disk electrode (left) and its connection with Bi-Potentiostat (right)
The main unit adopts the common three-electrode mode: sheath clip of the auxiliary
electrode is connected to counter electrode (CE); sheath clip of the reference electrode is
connected to reference electrode (RE); and that of the working electrode is connected to
the output wire of disk electrode (Disk Electrode). The slave unit uses two-electrode
potentiostatic mode: sheath clip of auxiliary electrode and the reference electrode are
connected to the ring electrode, and sheath clip of the working electrode is connected to
the disk electrode. This two-electrode potentiostatic mode is to control the potential
difference between the ring electrode the disk electrode.
Note: the potentiostats of the main unit and the slave unit both use field work mode.
In the process of disk electrode polarization, the generated intermediate reaches the
ring electrode. Due to the potential difference between disk electrode and ring electrode,
it will be further oxidated or reduced. And current on ring electrode can be measured and
displayed by the auxiliary channel potentiostat.
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For disk-ring electrode test, disk electrode is the main working electrode, while the
ring electrode is mainly used to monitor the intermediate product on the disk electrode. So
disk electrode generally still uses potentiodynamic scan testing, and the potential
difference between ring electrode and disk electrode is set to be a constant potential value,
as 2-47 in the ring electrode polarization parameter settings.
There are two sets of test data records. One is the polarization potential (Ed) and
polarization current (Id) on the main unit potentiostat (i.e. disk electrode) ; the other is the
polarization potential (the set value for the fixed Er) and polarization current Ir on the
slave unit potentiostat (i.e. ring electrode).
11.2.1 Data File
When the experiment is performed, the data will be saved in the file specified by Data
File. The Dir button can be used to display a list of all directories and files. This is
particularly useful if you forget the file names you have already used. However, before
CorrTest begins performing the first experiment in the Experiment List, you will be
warned if the file has already existed.
11.2.2 Disk electrode scanning parameters
Similar with potentiodynamic scanning, disk electrode can have a maximum of 4
independent polarization potential setpoints. Please see the potentiodynamic scanning.
11.2.3 Ring electrode polarization parameters
Polarization potential — ring electrode relative to the disk electrode polarization
potential, with unit of V/s.
11.2.4 Data Acquisition
If Sampl Freq(Hz) is chosen, the acquisition rate in Points/Second is specified.
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11.2.5 Axis Type
When the experiment is performed, the data will be displayed as specified by the Axis
Type. CorrView can be later used to display the data in other formats.
11.2.6 Pstat/Gstat
For bipotentiostat users need to do settings for the main & slave unit respectively.
Parameters of them can be the same or different. With buttons of “main unit”and “slave
unit”, users can set the current range switching, signal gain, low-pass filter switches,
digital smoothing, scan (polarization) delay time and so on. Please note real ground must
be chosen for earthing mode.
11.2.7 Cell Setting
See Cell Setting 9.1.
12. Impedance
CS350 series use dual signal correlation integral system to improve the impedance
measurement accuracy. The test frequency ranges from 115KHz ~ 10μHz, and you can
automatically proceed electrochemical impedance test under open circuit potential, or any
DC bias. Built-in DC offset cancellation circuit can effectively improve the measurement
accuracy of the AC signal. Excitation amplitude of the sine wave from 0 ~ 2.5V can be set
arbitrarily.
For AC impedance measurement, it includes the following three methods:
① impedance ~ frequency sweep curve: It measures the system’s impedance
spectroscopy at different frequencies. It’s the most commonly used method to measure
impedance with the common form of Nyquist and Bode plots.
② impedance ~ time scanning curve: It measures the characteristics of impedance with
time’s change at a single frequency. It is used to track the dynamic processes of some
systems, such as conductivity.
③ impedance ~ potential sweep curves: It measures at a single frequency, the
characteristics of impedance of the system with the change of DC polarization potential.
It can be used to measure the differential capacitance curve and zero charge potential and
so on.
12.1 EIS vs Frequency
Experiment→Impedance→EIS vs Frequency
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OCP will display the current open circuit potential of the electrolytic cell (updated per
second). It is particularly useful for the users to determine whether the working electrode
is stable for impedance test.
12.1.1 Data File
When the experiment is performed, the data will be saved in the file specified by Data
File. The Dir button can be used to display a list of all directories and files. This is
particularly useful if you forget the file names you have already used. However, before
CorrTest begins performing the first experiment in the Experiment List, you will be
warned if the file already exists.
12.1.2 Polarization
“DC potential” is the set DC polarization potential of the working electrode during
impedance test. If the test needs to proceed under the open circuit potential (OCP), then
you can enter “0” and, select “relatively open circuit potential” in the drop-down box. This
moment the potentiostat will automatically give a total output of the pen-circuit potential
and the DC potential to the working electrode. If you need to do the impedance test under
50mV DC potential of anodic polarization, you can enter “0.05V” for “DC potential”.
If the test needs to be carried out at a fixed potential (such as-0.5V vs. SCE), you can
select “relative reference electrode” in the drop-down box and enter “-0.5V”. The
potentiostat will make the polarization potential of work electrode to be “-0.5V”, rather
than “-0.5V” OCP test potentials.
AC amplitude value is the amplitude value of the excitation signal of electrochemical
Impedance. For example, E = 0.012 sin (wt) V means AC signal amplitude is 12mV.
However, under the state of high frequency, the actual polarization amplitude of the
working electrode may be less than this value due to rate limitation of the amplifier and
the high-frequency transmission loss of the conducting wires,
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12.1.3 Frequency Sweep
Users should determine the frequency scanning method.
Frequency
scanning
starts from the initial frequency to the stop frequency, and the mode can be linear or
logarithmic. If you choose “linear mode”, the frequency test points will be evenly
distributed between start frequency and stop frequency. If the frequency range is “1k to
1Hz”, and you set 10 test points, the measuring frequencies will be “1Hz, 99.9Hz, 2 ×99.9
Hz ...”. Generally, users don’t select this mode except for special requirements.
If the selected mode is logarithmic, the sampled frequency data points will be evenly
distributed in Bode diagram. It is particularly useful for frequency scanning with
frequency range of 2 to 5 logarithmic orders of magnitude. If the frequency range is “1k
to 10Hz”, and you set 5 test points for every 10 octave, the measuring frequencies will be
10 × 100Hz, 10 × 100.2Hz, 10 × 100.4Hz, 10 × 100.6Hz, 10 × 100.8Hz, 10 × 101.0Hz. This
mode is usually selected.
12.1.4 Pstat/Gstat
The Experiments | Setup Pstat/Gstat... menu item is usually used to configure the
Pstat/Gstat for all experiments in the Experiment List. These settings apply to all
experiments where the Default Settings are selected.(See Pstat/Gstat Setting)
12.1.5 Cell Setting
See Cell Setting 9.1.
12.1.6 Analyzer Settings
Current range
Users can choose current range automatically or manually. If you select auto range,
you need to set up a high-frequency current range threshold which can limit the minimum
current range the potentiostat can use during high frequency measurements.
The figure
above indicates when the measuring frequency is above 1000Hz, the automatic range will
be no less than 2mA. High-frequency range is defined by the user. The set value in the
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figure shows that fH> 1000Hz is high frequencies, fL <10Hz is relatively low frequency,
and 10 ~ 1000Hz is in the middle range.
The impedance of the working electrode is different in face of high frequency signal
and low frequency signal. If accuracy improvement is needed for measurement results, the
setting for current range is varied. The user can select different “current-range” based on
frequency band. Generally, current-range under low frequency band should be smaller
than that under high frequency band. If the users set range inappropriately, the measured
impedance spectrum curve may have large noise. Or if they frequently change the range,
there will be obvious turning point in the curve. In such cases, the users should re-set. By
observing signal amplitude in the waveform display, users can check if the current range
setting is appropriate.
Bandwidth Settings
Bandwidth Setting is used to change the frequency response bandwidth of potentiosta.
When the capacitance value increases, the bandwidth of the potentiostat will be narrower,
the high-frequency performance will decrease, but stability will enhance. Bandwidth
switching is set based on the critical frequency fc. When measuring frequencies are above
fc, generally you should choose a smaller capacitance (or turn it off). The instrument has
high bandwidth, so there will not be false impedance spectra in high frequency area. But
for impedance test of the high impedance system, it may result in shock. You may have to
increase the capacitance values. To check if a shock appears, you can observe the
amplitude of signal and the form of wave in waveform diagram.
After the measured frequencies are below fc, you should select the second-grade
capacitance, and its value should be no less than that of the first grade. The instrument has
a relatively low bandwidth.
When fc> 10Hz, bandwidth setting capacitance is 22pF; when fc <= 10Hz, it is
470pF, in order to improve the signal stability.
For the filter settings, see 9.5 filter settings within the instrument settings.
DC Bias Compensation
DC Bias Compensation is used to eliminate DC level which is superimposed on the
potentiostat or the current output signal. It is used to increase the AC magnification of
potential or current signals and increase impedance measurement accuracy. CS350
instrument automatically uses internal bias elimination of potential and current, and thus
impedance measurement accuracy is improved. During impedance measurement, you are
recommended to at least open the “bias compensation” option. If the amplitude of “AC
excitation” signal is less than 100mV, you can open “signal enhancement” option.
Integration Time
Integration can be divided into automatic and manual integration. Increasing the
integration time can improve the impedance measurement accuracy, and reduce the impact
of noise on the measurement results. Integration time can be set to be the number of cycles
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or time (in seconds). The integration time indicates time cost at each frequency point. The
longer the integration time, the higher the measurement accuracy, and the more time it
takes.
Delay time is the waiting time between measurements of two frequencies. Before the
measurement of the next point, the internal frequency analyzer will wait for a period of
time, allowing electrodes to keep balanced. The delay time is usually not needed for the
electrochemical system.
12.1.7 The impedance spectrum fitting
CorrTest uses Zview software as a tool to analyze impedance spectroscopy and graph.
Zview is powerful for impedance analysis, and it can do complex plane diagram &Bode
diagram about data files. It allows users to create a variety of equivalent circuit and do
data fitting. It has functions of graph’s locally zooming in, curve smoothing, data
correction and so on. Zview can output the graphics to a printer or clipboard, and you can
also paste a graphic into a Word document.
Generated impedance data files of CorrTest (. Z) is fully compatible with Zview. Users
can directly click on “Zview Drawing” menu after data collection, and introduce one or
more data files from the “Documents” → “Data File” menu, and then select a variety of
graphics selection method in the “Options” → “activities graphics” menu.
If you want to change the graphics coordinate text, you can right-click the menu, select
“Settings” to modify, and select “Text” to insert whatever text in the graphics. If you want
to change the color, line pattern, or mark, etc., you can do settings in the pop-up diabox of
“File” → “Data File” menu..
Equivalent circuit fitting
From the Tools menu, select “Equivalent Circuit”, then you can make a strong analysis
of impedance spectroscopy. Users can set up equivalent circuit of their own or just choose
the classic equivalent circuit. In the equivalent circuit window, select “Model” → “Edit
equivalent circuit”, then you can start the simulation or fitting.
Graph copy
Right-click the mouse button, from the pop-up menu, select “copy graphics to the
clipboard”, then the graphics can be copied to the Windows clipboard. And then in Word,
via the “Edit” → “Paste” menu, graphics will be directly inserted into Word document.
Details about Zview and usage, please refer to its Help files
12.2 EIS vs Time
Experiment→Impedance→EIS vs Time
It measures the characteristics of impedance with time’s change at a single frequency,
and is used to track the dynamic processes of some system, such as conductivity.
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OCP will display the open circuit potential of the current electrolytic cell (updated per
second). This is particularly useful for the user to determine whether the working electrode
is stable for impedance test.
12.2.1 Data File
When the experiment is performed, the data will be saved in the file specified by Data
File. The Dir button can be used to display a list of all directories and files. This is
particularly useful if you forget the file names you have already used. However, before
CorrTest begins performing the first experiment in the Experiment List, you will be
warned if the file already exists.
12.2.2 Polarization
“DC potential” is the set DC polarization potential of the working electrode during
impedance test. If the test needs to proceed under the open circuit potential (OCP), then
you can enter “0” and, select “relatively open circuit potential” in the drop-down box. This
moment the potentiostat will automatically give a total output of the pen-circuit potential
and the DC potential to the working electrode. If you need to do the impedance test under
50mV DC potential of anodic polarization, you can enter “0.05V” for “DC potential”.
AC amplitude value is the amplitude value of the excitation signal of electrochemical
Impedance. For example, E = 0.012 sin (wt) V means AC signal amplitude is 12mV.
However, under the state of high frequency, the actual polarization amplitude of the
working electrode may be less than this value due to rate limitation of the amplifier and
the high-frequency transmission loss of the conducting wires,
12.2.3 Time Scan
Perform EIS at a single frequency over several points by setting the high and low
frequency, and setting point spacing to linear and the desired number of points.
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12.2.4 Pstat/Gstat
The Experiments | Setup Pstat/Gstat... menu item is usually used to configure the
Pstat/Gstat for all experiments in the Experiment List. These settings apply to all
experiments where the Default Settings are selected.(See Pstat/Gstat Setting)
12.2.5 Cell Setting
See Cell Setting 9.1.
12.3 EIS vs Potential
Experiment→Impedance→EIS vs Potential
The method is used to measure characteristics of single-frequency impedance under
different DC polarization potential. The potential is stepped from the “initial potential” to
“terminate potential”.,It is mainly used for Mott-Schottky (M-S diagram) curve test. M-S
diagram has been extensively used to study the semiconductor passivation film on the
surface of metals. It can determine carrier’s type and concentration and the flat band
potential, thereby contributing to the study of semiconductor function of a passivation film.
When the passivation film is in contact with the solution medium and the space charge
of the semiconductor passivation film is in the depletion state (remove majority carriers
from the space charge region and minority carriers is not present), for the space charge
capacitance (Csc) and the measured potential (measured voltage, Vm) , there is the
following linear relationship:
Where, Vfb is flat band potential, Nd and Na are donor and acceptor carrier
concentration, ε is the relative permittivity,, ε0 is the permittivity of vacuum, A the
electrode surface area, k is Boltaman constant, T is absolute temperature, e is the electric
charge.
Passivation film has a double structure. Since the composition and the crystal structure
of the inner and outer layer of the passivation film is different, semiconductor type of the
inner and outer layers is different either. And thus two space charge layers are formed
inside the passivation film, that is, the solution /passivation film interface space charge
layer and the passivation film inner layer /outer layer interface pn junction capacitance.
Because both pn and passivation film capacitance are small, in the impedance ~ potential
sweep, high-frequency sine wave is generally used for measurement.
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OCP will display the actual open circuit potential of the electrolytic cell (updated per
second).. This is particularly useful for the user to determine whether the working
electrode is stable for impedance test.
12.3.1 Data File
When the experiment is performed, the data will be saved in the file specified by Data
File. The Dir button can be used to display a list of all directories and files. This is
particularly useful if you forget the file names you have already used. However, before
CorrTest begins performing the first experiment in the Experiment List, you will be
warned if the file already exists.
12.3.2 Polarization
“DC potential” is used to set the DC polarization potential of the working electrode
during impedance test. If the test runs around the open circuit potential (OCP), then you
can enter “0” and, select “versus OCP” in the drop-down box. This moment the
potentiostat will automatically give a total output of the pen-circuit potential and the DC
potential to the working electrode. If you need to do the impedance test under 50mV DC
potential of anodic polarization, you can enter “0.05V” for “DC potential”.
AC amplitude value is the amplitude value of the excitation signal of electrochemical
Impedance. For example, E = 0.012 sin (wt) V means AC signal amplitude is 12mV.
However, under the state of high frequency, the actual polarization amplitude of the
working electrode may be less than this value due to rate limitation of the amplifier and
the high-frequency transmission loss of the conducting wires,
12.3.3 Potential Parameters
“Initial potential”---- it is the initial DC electrical level of the working electrode set in
impedance ~ potential sweep. “polarization potential” drop-down box ---- you can choose
potential applying means, thereby changing the reference potential of all the set points of
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polarization potential.
“Termination potential”---- it is the stop potential set in impedance ~ potential sweep.
“Potential incremental”---- it is increased with the form of steps; users can do singlefrequency impedance measurement at each step potential point.
12.3.4 Pstat/Gstat
The Experiments | Setup Pstat/Gstat... menu item is usually used to configure the
Pstat/Gstat for all experiments in the experiment list. These settings apply to all
experiments where the Default Settings are selected.(See Pstat/Gstat Setting)
12.3.5 Cell Setting
See Cell Setting 9.1..
13. Charging/Discharging
13.1 Battery Charging/Discharging
Experiment→Charging/Discharging→Battery Charging/Discharging
A sequence of Constant Current and Constant Potential actions within a loop (to define
the number of desired cycles) to create a cyclic charge-discharge sequence with charging
and discharging performed by constantly applied current with opposite sign. The charge
and discharge portions of the loop are separated by a Constant Potential action allowing
the cell to be maintained at a fixed potential which is terminated based either on a set time
or until a current or capacity limit is reached as set by the user.
The fixed potential used for this intermediate step is often the potential at which the
charging step terminated. Additional actions can be added to or removed from this
sequence as desired.
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13.1.1 Data File
When the experiment is performed, the data will be saved in the file specified by Data
File. The Dir button can be used to display a list of all directories and files. This is
particularly useful if you forget the file names you have already used. However, before
CorrTest begins performing the first experiment in the Experiment List, you will be
warned if the file already exists.
13.1.2 Experiment
Charge Current---- with different connecting ways of the electrode, the charging
current symbol will be different. If the working electrode is connected to battery positive,
and the reference & auxiliary electrodes are connected to the battery negative, the
displayed open circuit potential will be positive. Then enter a positive value and it
indicates charging.
Constant current - constant voltage conversion ---- it’s the critical voltage when
charging process is changed from constant current mode to constant voltage mode.
According to the charging rules, generally constant current charging mode is adopted in
the early stage of charging. When the battery voltage is higher than the critical voltage,
the charging will turn into constant voltage mode, and this moment the charging current
will gradually decrease with time. When it decreases to the cutoff current of the constant
voltage charging (usually 10 to 20% of the charging current), the software will
automatically disconnect the charging circuit.
Discharge current ---- if the working electrode is connected to battery positive, and
the reference & auxiliary electrode are jointly connected with battery negative, then enter
a negative value in the discharge current input box, it indicates the discharge.
Discharge critical voltage ---- in discharging process when the voltage drops to the
critical voltage, it will stop the discharge in order to avoid excessive discharge.
Charge-discharge interval ---- during this time interval, the battery is in the open
circuit.
Maximum charge and the longest discharge time ---- after a period of time of battery
charging (or discharging), if the specified critical voltage hasn’t yet been reached, the
charging (or discharging) will stop, and turn to discharging (or charging).
Cycles ---- one complete cycle includes a charging and a discharging process. This
parameter specifies the total number of cycles performed throughout the experiment.
When the number is achieved, the experiment will be stopped.
“Time unit” drop-down box ---- it lets you specify the time unit of charging and
discharging. You can select “seconds”, “minute” and “hour.”
Based on the current value set by the user, the Software will automatically select an
appropriate current range without user settings.
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13.1.3 Pstat/Gstat
The Experiments | Setup Pstat/Gstat... menu item is usually used to configure the
Pstat/Gstat for all experiments in the experiment list. These settings apply to all
experiments where the Default Settings are selected.(See Pstat/Gstat Setting)
13.1.4 Cell Setting
See Cell Setting 9.1.
13.2 Galvannostatic Charging/Discharging
Experiment→Charging/Discharging→Galvannostatic Charging/Discharging
It is used to measure characteristics of cyclic charge-discharge of the electrode
material (such as a secondary battery or super capacitor electrode material) under a
constant current and test the cycle life of the electrode material. Before starting the test,
the Start button is inactive. Only when the user specifies a valid file name can the start
button be activated. All subsequent data will be saved in the created file.
13.2.1 Data File
When the experiment is performed, the data will be saved in the file specified by Data
File. The Dir button can be used to display a list of all directories and files. This is
particularly useful if you forget the file names you have already used. However, before
CorrTest begins performing the first experiment in the Experiment List, you will be
warned if the file already exists.
13.2.2 Charging/Discharging Current
Charge Current ---- if the battery positive is connected to the working electrode, then
enter a positive number, indicating the charging.
Discharge current ---- if the battery positive is connected to the working electrode,
then enter a negative number, indicating the discharging.
13.2.3 Condition for switch of Charging/Discharging
Charge and discharge time ---- set the stage charging and discharging time.
“When the potential (V)” <Ec (relative to the reference electrode), Ec for the user
settings that material has been fully discharged, the instrument will switch to the charging
state, when the constant current charging process after potential than Ed (relative reference
electrode), it indicates that the material charge has been completed, to complete a
measurement cycle, and re-enter the discharge state.
Cycles ---- one complete cycle includes one charge and one discharge process, this
parameter specifies the total number of cycles performed throughout the experiment, this
number is reached, the experiment will be stopped.
“Time unit” drop-down box ---- Lets you specify the charge and discharge time unit,
you can select “seconds”, “minute” and “hour.”
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For charge-discharge potential value users can select “relative reference” or
“relatively open.”
13.2.4 Pstat/Gstat
The Experiments | Setup Pstat/Gstat... menu item is usually used to configure the
Pstat/Gstat for all experiments in the experiment list. These settings apply to all
experiments where the Default Settings are selected.(See Pstat/Gstat Setting)
13.2.5 Cell Setting
See Cell Setting 9.1.
14. Misc.Techniques
14.1 Electrochemical Noise
Experiment→Misc.Techniques→Electrochemical Noise
This test method is mainly used
for monitoring changes of the noise
potential and the noise current (zero
resistance current or galvanic current)
with time. Length of monitoring time
can be set accordingly.
For the CS-series workstations,
the noise signal (or the galvanic
current) measurements is different
from other methods because it does not
require polarization state. In the noise
/ galvanic current measurements, the
working/galvanic electrode Ⅰ is
connected to the green sheath clip of
the electrode cable, and working (galvanic) ElectrodeⅡis connected to the electrode cable
ground end GND wire (black sheath clip), and the reference electrode is still connected to
the yellow sheath clip. (See the right figure.)
Run CorrTest software, select electrochemical noise measurements, and at this time
the software window will appear junction potential (mixed potential) and galvanic current.
If the current value is positive, it means the working /galvanic electrodeⅠis anodic and
the working (galvanic) Ⅱ is a cathode. The current is flowing from electrode Ⅰ to
electrodeⅡ. A negative current is the opposite.
During measurement, potentiostat automatically switches the range according to the
magnitude of current.
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14.1.1 Data File
When the experiment is performed, the data will be saved in the file specified by Data
File. The Dir button can be used to display a list of all directories and files. This is
particularly useful if you forget the file names you have already used. However, before
CorrTest begins performing the first experiment in the Experiment List, you will be
warned if the file already exists.
14.1.2 Data Acquisition
If Sampl Freq(Hz) is chosen, the acquisition rate in Points/Second is specified.
14.1.3 Axis Type
When the experiment is performed, the data will be displayed as specified by the Axis
Type. CorrView can be later used to display the data in other formats.
14.1.4 Pstat/Gstat
The Experiments | Setup Pstat/Gstat... menu item is usually used to configure the
Pstat/Gstat for all experiments in the Experiment List. These settings apply to all
experiments where the Default Settings are selected.(See Pstat/Gstat Setting)
14.1.5 Cell Setting
See Cell Setting 9.1.
14.2 Data logger
Experiment→Misc.Techniques→Data logger
The data logger is used to record sync external signal. A maximum of six external
signals can be recorded simultaneously. (Two channels have already been used for internal
electrochemical measurement). This test method is completely independent from other
electrochemical tests, i.e., there will be no interaction between potentiostat’s work and
external signal recording. Before the test, the Start button is inactive. Only when the user
specifies a valid file name will it be activated. All subsequent data will be saved in the
created file.
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14.2.1 Data File
When the experiment is performed, the data will be saved in the file specified by Data
File. The Dir button can be used to display a list of all directories and files. This is
particularly useful if you forget the file names you have already used. However, before
CorrTest begins performing the first experiment in the Experiment List, you will be
warned if the file already exists.
14.2.2 Date Record
Total Time — recording the total time.
Sampling Data — allowing to select the group signal channel.
14.2.3 Data Acquisition
If Sampl Freq(Hz) is chosen, the acquisition rate in Points/Second is specified.
14.3 Electrochemical Stripping/Deposition
Experiment→Misc.Techniques→Electrochemical Stripping/Deposition
In this test method, a constant polarization potential is imposed onto the working
electrode, and at the same time the user should monitor the change of polarization current
with time. The polarization time may be specified by the user, and it can also be specified
when the current reaches a certain polarization value, letting CorrTest automatically
terminate the testing process.
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14.3.1 Data File
When the experiment is performed, the data will be saved in the file specified by Data
File. The Dir button can be used to display a list of all directories and files. This is
particularly useful if you forget the file names you have already used. However, before
CorrTest begins performing the first experiment in the Experiment List, you will be
warned if the file already exists.
14.3.2 Deposition Parameters
Polarization Potential (V) is the potential imposed on the test system. For CS Series
electrochemical workstation, if the “polarization potential” is relative to the open circuit
potential, the negative value indicates cathodic polarization, while positive value indicates
anodic polarization.
Clicking on the drop-down box, users can also choose the applying way of
polarization potential.
Polarization time — you can specify the length of potentiostatic polarization time;
time unit can be “second”, “minute”and “hour.”
Experiment TerminationIf you select “Based on the current” checkbox and set the
silent time and current sampling interval, CorrTest will automatically terminate
potentiostatic polarization tests when the polarization current value is higher than the
specified maximum (anode current) or lower than the specified minimum (cathode
current).
If you choose “Based on DI / Dt Stop” checkbox, CorrTest will automatically
terminate potentiostatic polarization tests when the DI / Dt is greater than a certain set
value.
If you choose the “Disabled” checkbox, the above two test termination conditions are
both discarded.
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14.3.3 Data Acquisition
If Sampl Freq(Hz) is chosen, the acquisition rate in Points/Second is specified.
14.3.4 Axis Type
When the experiment is performed, the data will be displayed as specified by the Axis
Type. CorrView can be later used to display the data in other formats.
14.3.5 Pstat/Gstat
The Experiments | Setup Pstat/Gstat... menu item is usually used to configure the
Pstat/Gstat for all experiments in the experiment list. These settings apply to all
experiments where the Default Settings are selected.(See Pstat/Gstat Setting)
14.3.6 Cell Setting
See Cell Setting 9.1.
15. Data View
15.1 CV Data View
In the “potentiostat” mode (including those test methods based on constant potential,
constant current and galvanic current, etc.), this Data View window graphically shows data
in real time, and has “Stop”, “Reverse”, “Pause” and other graphical buttons.
In the mode of data logger, it shows the outside signal path at work, and recorded data
and graphs at present.
Name of the data files will be displayed in the title bar of the window, and the adopted
test methods (e.g. constant potential polarization, potentiodynamic scanning, etc.), the
working parameters (such as scan rate, measurement time, work state, the total amount of
data, etc.), as well as the progress and completion percentage will all be displayed at the
bottom of the window.
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CorrTest software will automatically select the best starting and ending point in the
coordinate, and dynamically refresh the graph.
15.1.1 Graph Coordinate
By clicking on the drop-down box in the right side of graph options, you can change
the dynamic graph display. Users can select 7 kinds of graph coordinates, and they can
also select coordinate units (mV, V, mA, A) according to the value of potential and current.
“E vs. time” — the abscissa is the time in “second”; the vertical axis is electrode
potential.
“I vs. time” — the abscissa is the time in “second”; the vertical axis is current.
“E vs. I” — the abscissa is the current; the vertical axis is electrode potential.
“I vs. E” — the abscissa is electrode potential; the vertical axis is current.
“E vs. Lg I” —the abscissa is the logarithm value of current; the vertical axis is
electrode potential.
“E + I vs. time” — there are two graphs. The abscissa is time, and the vertical axis
separately is electrode potential and polarization current.
“Q vs. time” — the abscissa is time and the vertical axis is the Integral electric quantity.
This option only works under potentiostat mode. If data logger and potentiostat are
both at work, then display varies according to user-selected menu.
15.1.2 Work Pass
Click on the drop-down box on the right side of the working channel, under the mode
of data logger, then the corresponding data of the working channel will be displayed.
This option is available only in data logger mode (recording external signals). If the
data logger and potentiostat are both at work, then display varies according to user-selected
menu.
15.1.3 Live Data
Live data shows the latest collection of data. From left to right it’s time (s), potential
(mV), and current (μA).
When the users want to know the value of a point on the graph, they can move the
cursor onto the graph area, then immediately there will be a synchronized display of the
value on the right side of the cursor. For example if you select “E vs. time“, the text is the
time (s) and potential (mV). And when you switch to the “E vs. I”, the content is the current
(mA) and the potential (mV).
15.1.4 Zoom in
When users need to observe graphs or data in a local position during the test, they can
left-press the mouse button on the upper left side of the certain area, and drag to the lower
right side, and then release the button. This local graph will immediately be zoomed in
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and fill up the entire diabox. The graph will not be updated, but this time test system of
CorrTest is still scanning and collecting data signals. If you want to go back to the original
status, just click the mouse on the graph.
15.1.5 Stop and Pause
Click on
to terminate the ongoing test. Click on
to pause the test.
15.1.6 Reverse Scan
A click on
can reverse scanning. But this is just applicable for potentiodynamic
sweep and cyclic voltammetry test. Click on this button, then the scanning direction will
immediately be reverse, but the scan rate remains the same. If click again, the scan will go
back to the original direction. This button allows users to change the scan direction at any
time in order to study the cyclic characteristics of the electrochemical reaction.
15.1.7 Polarization /Nature Switch
Click on
then you can change the polarization/natural state of electrode.
15.1.8 Print graph
Click on the print button then you can immediately output the displayed real-time
graph to the printer.
15.1.9 Lock Graph
A click on
allows users to lock the graph diabox. You can watch the progress of
testing while doing other operations (such as parameter fitting, document editing, etc.). If
you want to unlock it, just click on it again.
15.2 EIS Data View
CorrTest is able to display the test data of the impedance spectroscopy. Users can read
test data by moving the mouse onto the graph area on the screen that displays the real part,
imaginary part, complex modulus, phase angle and frequency. The measured data is
automatically saved.
After selecting the box of “locked the data point”, the user can read the coordinate of
the data points in “Nyquist” or “Bode” graph (including the real part, the imaginary part,
frequency, impedance modulus and phase angle) by locking the mouse.
In the title bar of the diabox the data file names are displayed. At the bottom of the
diabox there are displays of the operating parameters, such as the polarization amplitude,
DC level, scanning range, current range and so on. CorrTest software will automatically
select the best starting and ending coordinates, and make adjustments for display mode of
the coordinate.
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User’s Manual
15.2.1 Data
When the users want to know the value of a point on the graph, they can move the
cursor onto the graph area, then immediately there will be a synchronized display on the
right side of the cursor.
15.2.2 Zoom In
When users need to observe graphs or data of a local position during the test, they can
left-press the mouse button on the upper left side of the certain area, and drag to the lower
right side, and then release the button. This local graph will immediately be zoomed in
and fill the entire diabox. The graph will not be updated, but this time test system of
CorrTest is still scanning and collecting data signals. If you want to go back to the original
status, just click the mouse on the graph.
Note: Due to a large amount of data processing in the test, users are recommended to
use this function after testing.
15.2.3 Stop
Click on
to terminate the ongoing test. Click
to pause the test.
15.2.4 Real-time Waveform Show
The waveform acquisition window is used to display the acquired potential and
current waveforms in the process of EIS measurements, guiding the user to set the
appropriate parameter of “minimal high frequency range” and “bandwidth response” in
the impedance test window. If the potential and current waveforms have much noise, the
capacitance of the bandwidth filter needs to be increased for preventing shock.
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User’s Manual
In impedance test of high resistance system, if the bandwidth response capacitance
doesn’t open in “Impedance test”→“Analyzer” window, it may cause shock phenomenon
during the test. As shown in the graph below, there is no sine wave signal in the waveform
signals of the current and potential, and the amplitude is not the same for the two signals.
It indicates the test system does not correctly follow the sinusoidal signal, and that a shock
occurs.
Figure2-6. The current and potential waveform in shock
After changing the bandwidth capacitance in the “Analyzer” window to “22pf”,
normal sine wave signal can be seen, indicating that the instrument works well and can
respond with the imposed sine wave signals. The acquired waveform is shown in Figure
below. The amplitude of the potential signal is 10mV, which is in accordance with that of
the imposed signal. The current is in the range of 35μA, conforming to the selected current
range 200μA. If the current amplitude is too large (in a square wave) or too small (signal
noise ratio is too low), the measured impedance will have big errors. In this case, the
minimum high-frequency current range in the analyzer needs to be re-adjusted.
If it’s just the noise of current signal being relatively large, high input impedance of
reference circuit (such as high-impedance coating) may be the cause, resulting in relatively
large current noise. At this time it’s needed to increase the bandwidth filter capacitance,
thus can increase the stability of the test system.
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User’s Manual
Figure2-7. The sine wave signal in normal
16. Date Analysis
16.1 Corshow Date Analysis
Find the Corshow software in the installation CD. After installation is completed,
open the software. The Corshow software interface is as below:
CorrTest uses Corshow to analyze test data. It can display data by multiple coordinates
with functions of graph locally zooming, curve smoothing, data correction,etc. Also it can
do calculations such as linear fitting, tafel fitting and so on. However the calculating results
by the software may be different from results of “parameter fitting”.. Graphs can be output
to a printer or a clipboard by Corshow software, and can be pasted into the Word document
directly.
Data files (.cor) generated from CorrTest is fully compatible with Corshow software.
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User’s Manual
Users can directly click on “Corshow Drawing” menu after data acquisition, and introduce
one or more data files from “File”→ “Import Data” menu and then select various graphic
coordinates (such as “E vs. time”, “E vs.I”, “E vs.logI”, etc.) from “Standaxis” menu.
When the graph is displayed disproportionately, you can right-click the mouse button to
get Menu in the graph area, and select “Auto Zoom” to support full graph.
Corshow software also has strong data calculation power. It can calculate anodic and
cathodic Tafel slope, as well as the corrosion rate. You can use the “Auto Tafel fit” or
“Auto Tafel Fit (between cursors)” and other methods to calculate the electrochemical
parameters and corrosion rate. If fitting curve (blue) is well matched with the original data
curve, it means the results have high reliability. Fitting results can be pasted onto the
drawing via “Auto Insert”, as shown in Figure 2-8.
Figure 2-8. Polarization curve of A3 steel
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User’s Manual
16.2 Corrosion Rate Calculation
16.2.1 Polarization Resistance
Polarization curves for the data processing module polarization curves for each
segment to adopt different methods for linear and Tafel region using a linear regression
calculation.The polarization resistance (Rp) is calculated as the inverse of the slope of the
I vs. E data near the Open Circuit potential.
Rp (Ohms) is the inverse of the slope of the I vs E data.
Ecorr (Volts) is the potential at which the current changed polarities. This usually
corresponds to the open circuit potential of the system.
Estimated Icorr(Amps/cm2) is based on the Stern-Geary relationship (Stern and Geary,
J. Electrochem. Soc. 104 56, 1957):
Icorr(A/cm^2) =(Ba × Bc) / (2.3×(Ba+Bc) ×Rp)
Since the Tafel slopes (Ba and Bc) cannot be calculated from this data, 0.12 V/decade
are often used, resulting in the approximation (Mansfeld, Advances in Corrosion Science
and Tech., 6 Ed. Fontana and Staehle, Plenum Press, p. 163, 1976):
Stern Geary Coef. = (Ba × Bc) / (2.3×(Ba+Bc)) = 0.026
Icorr (A/cm^2) = 0.026 /Rp
The Stern-Geary Coefficient is specified in the Setup | Cell... window.
Corrosion Rate is calculated from:
MPY=(Icorr(A/cm^2)×EquivWeight(g/equivalent)×393.7(mils/cm))/(Density
(g/cm3)×96500(coulomb/equivalent))
mmPY=(Icorr(A/cm^2)×EquivWeight(g/equivalent) × 10(mm/cm)) / (Density(g/cm3)
× 96500(coulomb/equivalent))
The Corrosion Rate calculations are only possible if Density and Equivalent Weight
values were entered in the Setup | Cell... window.
Note: The calculated values depend on the proper selection of data to be used by this
function. In addition, data artifacts or improper experimental technique may cause large
discrepancies in the results. So the users must depend on their own knowledge of
electrochemistry or corrosion to determine if the values are valid.
16.2.2 Corrosion Rate Calculation
Date Analysis→Corrosion Calculation
This dialog box is used for corrosion calculation according to the electrode kinetic
equations. The cell parameters need to fill well.
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User’s Manual
16.2.3 Three calculation methods
LRR Fi t — it is used to do linear regression calculations of data in the range of ±15mv
on the cathode or anode polarization curve selected by the user, and thus to calculate the
linear polarization resistance Rp value of the system. It is also used to calculate the
corrosion rate according to the formula Vcorr=B/Rp where Stern B value is given by the
user. For linear polarization, the polarization resistance of the cathode and the anode
segment may be somewhat different, so both results of Rp value will be displayed
simultaneously. But the corrosion rate will be calculated according to the average of the
two.
Tafel Fit (3 parameters) — by fitting the weakly polarized area, it will calculate the
anode / cathode Tafel slope (bA, bC) , the corrosion current density icorr, and corrosion rate
vcorr. These calculations are dependent on the present electrode parameters.
Tafel Fit (4 parameters) — using 4 parameters method, it can calculate Tafel slopes
(bA and bC), limiting diffusion current density iL, corrosion current density icorr and
corrosion rate vcorr by fitting anodic and cathodic weak polarization curves.
17. Contact us
If you have any suggestions or comments about this product, please contact us:
Wuhan Corrtest Instruments Co., Ltd
Our address: 501, Block B, Dingye building, International Enterprise Center,
Guanggu Avenue Donghu Development District, Wuhan, China.
URL: http://www.corrtest.com.cn
E-mail: [email protected]
Tel: +86-27-67849450,+86-27-67849890,+86-13971066778
Fax: +86-27-67849890-39
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Wuhan Corrtest Instruments Co., Ltd
501, Block B, Dingye building, International Enterprise Center,
Guanggu Avenue Donghu Development District, Wuhan, China.
http://www.corrtest.com.cn
2013.12
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