STUDY OF WEAR BEHAVIOUR OF RICE HUSK CERAMIC COMPOSITES RABISHANKAR BISWAL

STUDY OF WEAR BEHAVIOUR OF RICE HUSK  CERAMIC COMPOSITES RABISHANKAR BISWAL
STUDY OF WEAR BEHAVIOUR OF RICE HUSK
CERAMIC COMPOSITES
A THESIS SUBMITTED IN PARTIAL FULFILMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
Bachelors of Technology
in
Mechanical Engineering
By
RABISHANKAR BISWAL
Department of Mechanical Engineering
National Institute of Technology
Rourkela
2010
1
STUDY OF WEAR BEHAVIOUR OF RICE HUSK
CERAMIC COMPOSITES
A THESIS SUBMITTED IN PARTIAL FULFILMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
Bachelors of Technology
in
Mechanical Engineering
By
RABISHANKAR BISWAL
Under the Guidance of
Prof. S. K. ACHARYA
Department of Mechanical Engineering
National Institute of Technology
Rourkela
2010
2
National Institute of Technology
Rourkela
CERTIFICATE
This is to certify that thesis entitled, “STUDY OF WEAR BEHAVIOUR OF RICE
HUSK CERAMIC COMPOSITES” submitted by Mr. RABISHANKAR BISWAL in
partial fulfillment of the requirements for the award of Bachelors of Technology Degree in
Mechanical Engineering at National Institute of Technology, Rourkela (Deemed University)
is an authentic work carried out by him under my supervision and guidance.
To the best of my knowledge, the matter embodied in this thesis has not been submitted to
any other university/ institute for award of any Degree or Diploma.
Date:
Prof. S.K.Acharya
Dept. of Mechanical Engineering
National Institute of Technology
Rourkela-769008
3
CONTENTS
Page No.
CERTIFICATE
3
ACKNOWLEDGEMENT
6
ABSTRACT
7
LIST OF FIGURES
8
LIST OF TABLES
9
CHAPTER-1
CHAPTER-2
CHAPTER-3
INTRODUCTION
1.1
Background
10
1.2
Why a Composite?
10
1.3
Definition of a Composite
12
1.4
Characteristic of the Composites
13
1.5
Classification
13
1.6
Components of the Composite Material
16
1.7
Types of Composite Materials
19
1.8
Natural Fibre as Filler Material
21
1.9
Wear
21
1.10
Symptoms of Wear
23
LITERATURE SURVEY
2.1 Literature Review
24
2.2 Material selection
26
2.3 Fabrication methods of PMC
28
MATERIALS AND METHODS
4
3.1
Raw Materials
30
3.2
Preparation of Composites
31
3.3
Wear test
33
3.4
Standard methodology to conduct the wear test
36
3.5
Experimental Procedure
37
CHAPTER-4
EXPERIMENTAL RESULTS, CALCULATIONS
39-47
AND GRAPHS
CHAPTER-5
CONCLUSION
5.1
Conclusion
48
5.2
Recommendation for further research
49
REFERENCES
50-51
5
ACKNOWLEDGEMENT
It is with a feeling of great pleasure that I would like to express my most sincere
heartfelt gratitude to Prof.S.K.Acharya, Asst. Professor, Dept. of Mechanical Engineering,
NIT, Rourkela for suggesting the topic for my thesis report and for his ready and able
guidance through out the course of my preparing the report. I am greatly indebted to him for
his constructive suggestions and criticism from time to time during the course of progress of
my work.
I express my sincere thanks to Prof. R.K.SAHU, Head of the Department of
Mechanical Engineering, NIT, Rourkela for providing me the necessary facilities in the
department.
I thankful to Sri Ragavendra and Sri C. R. Deo for their co-operation in
experimental work. I am also thankful to Mr. N.P.Barik and all the staff members of the
department of Mechanical Engineering and to all my well wishers for their inspiration and
help.
Date:
RABISHANKAR BISWAL
ROLL NO.-10603064
6
ABSTRACT
In recent years composites have attracted substantial importance as a
potential structural material. The most basic & common attractive features composites that
make them useful for industrial applications are low cost, light weights, high specific
modulus, renewability and biodegradability.
Rice Husk ceramics composites are an
important area of interest these days for development of new composite materials. These
composites are gaining importance due to their non-carcinogenic and bio-degradable nature.
Rice Husk contains about 20% ash, 22% lignin, 38% cellulose, 18% pentosans, 2% moisture.
But once the husk is carburized in Nitrogen atmosphere it forms Rice Husk ash. This ash
contains 95% silica (SiO2), 1% K2O, 1% CaO, P2O5 & Na2O3, Fe2O3 & MgO. The silica in
rice husk exists in the amorphous form but became crystalline during combustion of the rice
husk. The ash as standalone is very useful in making insulation products, refractory materials,
Portland cement, masonry cement & pottery products. Now the scope of its usage is also
extended to paints & fertilizers. It increases abrasion characteristics & hence finds application
in aluminum industries.
Keeping this in view the present research work has been under taken with
an objective to explore the use of rice husk ash as potential filler in polymer composite and to
study its wear behavior. To study the wear properties the components made from these rice
husk ceramics is subjected to wear test using a Pin-on-Disc apparatus. Experiments have been
conducted under laboratory conditions to asses the wear behaviour of the rice husk ceramic
composites in polymer matrix. The change in weight is studied for a single velocity & various
loads applied to composites which vary in the percentage of filler & percentage of matrix.
The final result is drawn from the wear test. The conclusion helps us to predict the wear
behavior various constituents of rice husk ceramic composites under varying loads & a fixed
speed.
7
LIST OF FIGURES
Figure No.
No.
Title
Page
Fig 1.1
Classification of composite material
Fig 1.2
Classification of composite materials according
15
to fiber arrangements
20
Fig 2.1
Hand Lay-up technique
29
Fig 3.1
Set up to perform an Abrasive wear test on a pin on the disc
33
Fig 3.2
Specimen (composite) loaded as pin for performing wear test
34
Fig 3.3
Schematic of pin on disc wear test
37
Fig 4.1
Plot of percentage of filler vs measured density (M)
41
Fig 4.2
Plot of COF (y-axis) vs. Time (x-axis)
43
Fig 4.3
Plot of weight loss vs. Load for each sample
44
Fig 4.4
Plot of Dimensionless Wear rate vs. Load for each sample
45
Fig 4.5
Plot of specific wear rate vs. sliding distance (in m) (for 20N load)
46
Fig 4.6
Plot of specific wear rate vs. sliding distance (in m) (for 5N load)
47
8
LIST OF TABLES
Table No.
No.
Title
Page
Table 1.1
Advantages and limitations of polymeric matrix materials
Table 1.2
Symptoms & appearance of worn out surface corresponding
17
to each type of wear
23
Table 3.1
Specification of the pin-on-disc apparatus
35
Table 4.1
Calculation of weight of filler & polymer required for
making the composite
39
Table 4.2
Calculation of the total weight required being required
39
Table 4.3
Calculation of Theoretical Density (T)
40
Table 4.4
Calculation of void percentage
40
Table 4.5
The value of coefficient of friction vs. time when various
sample underwent the wear test for 300 seconds at a
velocity of 0.157 m/s.
33-34
Table 4.6
Weight Loss (in gm) during wear test in 300 seconds:
44
Table 4.7
Dimensionless wear rate under varying loads for various composites.
45
Table 4.8
Specific wear rate (K0) of the sample under load of 20N &
velocity of 0.157 m/s
46
Specific wear rate (K0) of the sample under load of 5N &
velocity of 0.157 m/s
47
Table 4.9
9
CHAPTER – 1
1.1
BACKGROUND
India endowed with an abundant availability of natural fiber such as Jute,
Coir, Sisal, Pineapple, Ramie, Bamboo, Banana etc. has focused on the development of
natural fiber composites primarily to explore value-added application avenues. Such natural
fiber composites are well suited as wood substitutes in the housing and construction sector.
The development of natural fiber composites in India is based on two pronged strategy of
preventing depletion of forest resources as well as ensuring good economic returns for the
cultivation of natural fibers.
The developments in composite material after meeting the challenges of
aerospace industry have cascaded down for catering to domestic and industrial applications.
Composites, the wonder material with light-weight; high strength-to-weight ratio and
stiffness properties have come a long way in replacing the conventional materials like metals,
wood etc. The material scientists all over the world focused their attention on natural
composites to cut down the cost of raw materials.
1.2
WHY A COMPOSITE?
Over the last thirty years composite materials, plastics and ceramics have been
the dominant emerging materials. The volume and number of applications of composite
materials have grown steadily, penetrating and conquering new markets relentlessly. Modern
composite materials constitute a significant proportion of the engineered materials market
ranging from everyday products to sophisticated niche applications. They are usually
optimized to achieve a particular balance of properties for a given range of applications.
While composites have already proven their worth as weight-saving materials,
the current challenge is to make them cost effective. The efforts to produce economically
attractive composite components have resulted in several innovative manufacturing
techniques currently being used in the composites industry. It is obvious, especially for
composites, that the improvement in manufacturing technology alone is not enough to
overcome the cost hurdle. It is essential that there be an integrated effort in design, material,
process, tooling, quality assurance, manufacturing, and even program management for
composites to be competitive with metals.
10
The composites industry has recognized that the commercial applications of
composites promise to offer much larger business opportunities than the aerospace sector due
to the sheer size of transportation industry. Thus the shift of composite applications from
aircraft to other commercial uses has become prominent in recent years.
Increasingly enabled by the introduction of newer polymer resin matrix
materials and high performance reinforcement fibers of glass, carbon and aramid, the
penetration of these advanced materials has witnessed a steady expansion in uses and volume.
The increased volume has resulted in an expected reduction in costs. High performance FRP
can be found in diverse applications as composite armoring designed to resist explosive
impacts, fuel cylinders for natural gas vehicles, windmill blades, industrial drive shafts,
support beams of highway bridges and even paper making rollers. For certain applications,
the use of composites rather than metals has resulted in savings of both cost and weight.
Some examples are cascades for engines, curved fairing and fillets, replacements for welded
metallic parts, cylinders, tubes, ducts, blade containment bands etc.
Further, the need of composite for lighter construction materials and more
seismic resistant structures has placed high emphasis on the use of new and advanced
materials that not only decreases dead weight but also absorbs the shock & vibration through
tailored microstructures. Composites are used not only for their structural properties, but also
for electrical, thermal, tribological, and environmental applications. Composites are now
extensively being used for rehabilitation/ strengthening of pre-existing structures that have to
be retrofitted to make them seismic resistant, or to repair damage caused by seismic activity.
Unlike conventional materials (e.g., steel), the properties of the composite
material can be designed considering the structural aspects. The design of a structural
component using composites involves both material and structural design. . The improved
structural properties generally result from a load-sharing mechanism. It has been found that
composites developed for structural applications also provide attractive performance in these
other functional areas as well. Composite properties (e.g. stiffness, thermal expansion etc.)
can be varied continuously over a broad range of values under the control of the designer.
Careful selection of constituent materials i.e. matrix & reinforcement type enables finished
product characteristics to be tailored to almost any specific engineering requirement.
11
Whilst the use of composites will be a clear choice in many instances, material
selection will depend on factors such as working lifetime requirements, number of items to be
produced (run length), complexity of product shape, possible savings in assembly costs and
on the experience & skills the designer in tapping the optimum potential of composites. In
some instances, best results may be achieved through the use of composites in conjunction
with traditional materials.
1.3
DEFINITION OF COMPOSITE
Given the vast range of materials that may be considered as composites and
the broad range of uses for which composite materials may be designed, it is difficult to agree
upon a single, simple, and useful definition. The most widely used meaning is the following
one, which has been stated by Jartiz [1] “Composites are multifunctional material systems
that provide characteristics not obtainable from any discrete material. They are cohesive
structures made by physically combining two or more compatible materials, different in
composition and characteristics and sometimes in form”.
The weakness of this definition resided in the fact that it allows one to classify
among the composites any mixture of materials without indicating either its specificity or the
laws which should given it which distinguishes it from other very banal, meaningless
mixtures.
Kelly [2] very clearly stresses that the composites should not be regarded simple
as a combination of two materials. In the broader significance; the combination has its own
distinctive properties. In terms of strength to resistance to heat or some other desirable
quality, it is better than either of the components alone or radically different from either of
them.
Beghezan [3] defines as “The composites are compound materials which differ
from alloys by the fact that the individual components retain their characteristics but are so
incorporated into the composite as to take advantage only of their attributes and not of their
short comings”, in order to obtain improved materials.
Van Suchetclan [4] explains composite materials as heterogeneous materials
consisting of two or more solid phases, which are in intimate contact with each other on a
12
microscopic scale. They can be also considered as homogeneous materials on a microscopic
scale in the sense that any portion of it will have the same physical property.
1.4
CHARACTERISTICS OF THE COMPOSITES
Composites consist of one or more discontinuous phases embedded in a
continuous phase. The discontinuous phase is usually harder and stronger than the continuous
phase and is called the ‘reinforcement‘ or ‘reinforcing material’, whereas the continuous
phase is termed as the ‘ matrix’.
Properties of composites dependent on the properties of their constituent
materials, their distribution and the interaction among them. The composite properties may be
the volume fraction sum of the properties of the constituents or the constituents may interact
in a synergistic way resulting in improved or better properties. Apart from the nature of the
constituent materials, the geometry of the reinforcement (shape, size and size distribution)
influences the properties of the composite to a greater extent. The concentration, distribution
and orientation of the reinforcement also affect the properties.
The shape of the discontinuous phase (which may by spherical, cylindrical, or
rectangular cross-sanctioned prisms or platelets), the size and size distribution (which
controls the texture of the material) and volume fraction determine the interfacial area, which
plays an important role in determining the extent of interaction between the reinforcement
and the matrix.
Concentration, usually measured as volume or weight fraction, determines the
contribution of a single constituent to the overall properties of the composites. It is not only
the single most important parameter influencing the properties of the composites, but also an
easily controllable manufacturing variable used to alter its properties.
1.5
CLASSIFICATION
Composite materials can be classified in different ways [5]. Classification based upon the
geometry of a representative unit of the reinforcement is convenient because it is the
geometry of the reinforcement that is responsible for the mechanical properties and high
performance of the composites. A typical classification is presented in table1.1. The two
broad classes of composites are (1) Particulate composites and (2) Fibrous composites.
13
1.5.1
Particulate Composites
As the name itself indicates, the reinforcement is of particle nature (platelets
are also included in this). It may be spherical, cubic, tetragonal, a platelet, or of other regular
or irregular shape, but it is approximately or roughly equiaxed or equal in shape. Thus,
particulate-reinforced composites include those reinforced by spheres, rods, flakes, and many
other shapes of roughly equal axes. In general, particles are not very effective in improving
fracture resistance but they enhance the stiffness of the composite to a limited extent. Particle
fillers are widely used to improve the properties of matrix materials such as to modify the
thermal and electrical conductivities, improve performance at elevated temperatures, reduce
friction, increase wear and abrasion resistance, improve machinability, increase surface
hardness and reduce shrinkage.
1.5.2
Fibrous composites
A fiber is characterized by its length being much greater compared to its cross-
sectional dimensions. The dimensions of the reinforcement determine its capability of
contributing its properties to the composite. Fibers are very effective in improving the
fracture resistance of the matrix since a reinforcement having a long dimension discourages
the growth of incipient cracks normal to the reinforcement that might other wise lead to
failure, particularly with brittle matrices.
Man-made filaments or fibers of non polymeric materials exhibit much higher
strength along their length since large flaws, which may be present in the bulk material, are
minimized because of the small cross-sectional dimensions of the fiber. In the case of
polymeric materials, orientation of the molecular structure is responsible for high strength
and stiffness.
14
Composite materials
Particle reinforced composites
Fiber reinforced composites
Multi layered
composites
Single layer
composite
Continuous fiber
reinforced
composites
Discontinuous fiber
reinforced composites
Random
orientation
Unidirectional
reinforcement
Laminates
Random orientation
Hybrids
Preferred
orientation
Bi-directional
reinforcement
Fig 1 .1
Classification of composites
15
Preferred orientation
Fibers, because of their small cross- sectional dimensions, are not directly usable
in engineering applications. They are, therefore, embedded in matrix materials to form fibrous
composites. The matrix serves to bind the fibers together, transfer loads to the fibers, and protect
them against environmental attack and damage due to handling. In discontinuous fiber reinforced
composites, the load transfer function of the matrix is more critical than in continuous fiber
composites.
1.6
COMPONENTS OF A COMPOSITE MATERIAL
In its most basic form a composite material is one, which is composed of at least
two elements working together to produce material properties that are different to the properties
of those elements on their own. In practice, most composites consist of a bulk material (the
‘matrix’), and a reinforcement of some kind, added primarily to increase the strength and
stiffness of the matrix.
1.6.1
Role of matrix in a composite
Many materials when they are in a fibrous form exhibit very good strength
property but to achieve these properties the fibers should be bonded to a suitable matrix. The
purpose of the matrix is to bind the reinforcements together by virtue of its cohesive and
adhesive characteristics, to transfer load to and between reinforcements, and to protect the
reinforcements from environments and handling. The matrix also provides a solid form to the
composite, which aids handling during manufacture and is typically required in a finished part.
The matrix isolates fibers from one another to prevent abrasion and formation of new surface
flaws and acts as a bridge to hold the fibers in place. A good matrix should have the ability to
deform easily under applied load, transfer the load onto the fibers and evenly distributive stress
concentration. Because the reinforcements are typically stronger and stiffer, the matrix is often
the “weak link” in the composite, from a structural perspective. As a continuous phase, it
controls the transverse properties, inter-laminar strength, and elevated-temperature strength of
the composite.
1.6.2
Materials used as matrices in composites
In its most basic form a composite material is one, which is composed of at least
two elements working together to produce material properties that are different to the properties
16
of those elements on their own. In practice, most composites consist of a bulk material (the
matrix) and a reinforcement of some kind, added primarily to increase the strength and stiffness
of the matrix.
(a)
BULK PHASES
(1)
Metal Matrices
Metal matrix composites possess some attractive properties, when compared with
organic matrices. These include (i) strength retention at higher temperatures, (ii) higher
transverse strength, (iii) better electrical conductivity, (iv) superior thermal conductivity, (v)
higher erosion resistance (vi) improvement in low temperature creep (vii) reduction in thermal
elongation etc. However, the major disadvantage of metal matrix composites is their higher
densities and consequently lower specific mechanical properties compared to polymer matrix
composites. Another notable difficulty is the high-energy requirement for fabrication of such
composites & sometimes development of magnetic properties.
(2)
Polymer Matrices
A very large number of polymeric materials, both thermosetting and
thermoplastic, are used as matrix materials for the composites. Some of the major advantages
and limitations of resin matrices are shown in Table 1.1.
Table 1.1 Advantages and limitations of polymeric matrix materials
___________________________________________________________________
Advantages
Limitations
___________________________________________________________________
Low densities
Low transverse strength
Good corrosion resistance
Low operational temperature limits
Low thermal conductivities
Low electrical conductivities
Translucence
Aesthetic Color effects
____________________________________________________________________
17
Generally speaking, the resinous binders (polymer matrices) are selected on the basis
of adhesive strength, fatigue resistance, heat resistance, chemical and moisture resistance etc.
The resin must have mechanical strength commensurate with that of the reinforcement. It must
be easy to use in the fabrication process selected and also stand up to the service conditions.
Apart from these properties, the resin matrix must be capable of wetting and penetrating into the
bundles of fibers which provide the reinforcement, replacing the dead air spaces therein and
offering those physical characteristics capable of enhancing the performance of fibers.
(3)
Ceramic Matrices
Ceramic fibers, such as alumina and SiC (Silicon Carbide) are advantageous in
very high temperature applications, and also where environment attack is an issue. Since
ceramics have poor properties in tension and shear, most applications as reinforcement are in the
particulate form (e.g. zinc and calcium phosphate). Ceramic Matrix Composites (CMCs) used in
very high temperature environments, these materials use a ceramic as the matrix and reinforce it
with short fibers, or whiskers such as those made from silicon carbide and boron nitride.
(b)
REINFORCEMENT
The role of the reinforcement in a composite material is fundamentally one of
increasing the mechanical properties of the neat resin system e.g. in a continuous fiber-reinforced
composite, the fibers provide virtually all of the strength and stiffness. All of the different fibers
used in composites have different properties and so affect the properties of the composite in
different ways. For most of the applications, the fibers need to be arranged into some form of
sheet, known as a fabric, to make handling possible. Different ways for assembling fibers into
sheets and the variety of fiber orientations possible to achieve different characteristics.
(c)
INTERFACE
It has characteristics that are not depicted by any of the component in isolation.
The interface is a bounding surface or zone where a discontinuity occurs, whether physical,
mechanical, chemical etc. The matrix material must “wet” the fiber. Coupling agents are
frequently used to improve wet ability. Well “wetted” fibers increase the interface surfaces area.
To obtain desirable properties in a composite, the applied load should be effectively transferred
18
from the matrix to the fibers via the interface. This means that the interface must be large and
exhibit strong adhesion between fibers and matrix. Failure at the interface (called debonding)
may or may not be desirable.
1.7
TYPES OF COMPOSITE MATERIALS
The composite materials are broadly classified into the following categories as shown in
fig 1.2 (a-e).
1.7.1
Fiber-Reinforced Composites
Reinforced-composites are popularly being used in many industrial
applications because of their inherent high specific strength and stiffness. Due to their excellent
structural performance, the composites are gaining potential also in tribological applications. In
this type composite the second phase is in the form of fibers dispersed in the matrix which could
be either plastic or metal. The volume fraction (Vf) varies from a few percentage to as high as
70%. Usually the fiber reinforcement is done to obtain high strength and high modulus. Hence it
is necessary for the fibers to posses’ higher modulus than the matrix material, so that the load is
transferred to the fiber from the matrix more effectively.
1.7.2
Dispersion Hardened Material
In this type of material, fine particles of sizes ranging from 0.01µm to 0.14µm
are dispersed in matrix. Their concentration varies from 1% to 15% by volume. These fine
particles impede dislocation movement in the material and therefore result in very high strength.
Also these materials posses improved high temperature strength and creep resistance.
1.7.3
Particulate composite
In this type of composites, 1µm to 200µm size particles are dispersed in the
matrix and volume fraction is generally between 0.01 Vf to 0.85 Vf.
19
(a) Random fiber (short fiber) reinforced
composites
(b) Particles as the reinforcement
(Particulate composites)
(c) Continuous fiber (long fiber) reinforced
Composites
(d) Flat flakes as the reinforcement
(Flake composites)
(e) Fillers as the reinforcement (Filler composites)
Fig 1.2 (a-e) Classification of composite materials according to fiber arrangements
20
1.8
NATURAL FIBER AS FILLER MATERIAL.
Natural fibers are lignocelluloses in nature these composites are gaining significance due
to their biodegradable nature. As a matter of fact they are emerging as realistic alternative to
glass reinforced composites in many applications. This is because of their low cast, light weight
and apparently environmentally superiority in comparison to synthetic fiber. Due these multiple
positive characteristics they are finding application in construction & building activities. In
addition the most advantage part of these composite is that natural fiber composite is their ease
of manufacturing & also they have higher fiber content for equivalent performance, reducing
more polluting base polymer content. The light weight natural fiber composites improve fuel
efficiency and reduce emission when used in auto applications.
1.9
WEAR
Wear is not an intrinsic property but it depends upon environment variables. These factors
include speed, loading cycles of use, temperature, pressure & presence of foreign materials. It
may be due to damage caused to the surface or removal to any or both of the exposed surface. In
most cases wear causes at the surface when they relative motion. In each case the removal of any
material is not the only criteria for the wear to occur, but also any damage to the surface without
material removal is also categorized as wear. But in most of the cases it is due to the interaction
of surfaces & in many cases it involves transfer of materials between the mating surfaces.
Types of wear: -- Classified by Burwell & Strang [6]
1.) Abrasive (the major cause of wear)
2.) Adhesive
3.) Erosion
4.) Fretting
5.) Chemical
1.) Abrasive Wear:-Abrasive wear can be defined as the kind of wear that occurs when a hard surface slides
or contuse to have relative motion with a softer surface. Hard materials or an asperity that
21
cut groves during this motion produces abrasive wear. These asperities can be those
present in the matting surface or any foreign material. This generation of wear fragments
hastens the process of wear if not removed.
2.) Adhesive Wear:-Adhesive wear can be defined as the kind of wear that occurs due to localized bonding
between the contacting or the mating surfaces. In this kind of wear there is actual transfer
of material between the mating surfaces. This transfer depends upon the degree of
hardness of the two mating surface. But the precondition for this kind of wear is the
intimate contact between the two surfaces. But the application of lubricating surface, oil
or grease decreases the tendency of this kind of wear.
3.) Erosive Wear:-This kind of wear is defined as process of metal removal due to impingement of solid
particles on a surface. This can also occur due to gas & liquid but the erosion by this
medium doesn’t carry. There are some specific characteristics of this kind of wear like: -when the angle of impingement is small, the wear produced is closely analogous to
abrasion. When the angle of impingement is normal then material flows by plastic flow
or is dislodged by brittle fracture.
4.) Corrosive Wear:-Most metals are thermodynamically unstable in atmosphere & reat with oxygen to form
oxides. These oxides form layer or scales over the surface. These scales are very loosely
bonded to the surface. They can be easily removed by treating it with acids, gases,
alkalis, etc. these kind of wear creates pits 7 gradually harm the metal surface.
5.) Fatigue Wear:-Fatigue Wear or fracture arises when the components is subjected to cyclic compression
& tension above a threshold stress. The surface wears down in this process. It starts with
the formation of microcraks & it gradually spreads & with repeated loading it actually
grows to the surface. Vibration is the common cause of fatigue.
22
1.10SYMPTOMS OF WEAR:-Table 1.2: Symptoms & appearance of worn out surface corresponding to each
type of wear
Types of Wear
Abrasive
Symptoms
Appearance of worn out surface
Presence of clean furrows cut out by Grooves
Adhesive
abrasive particles
Metal Transform is the main symptom
Erosion
surfaces.
Presence of abrasive in a fast moving Waves & troughs
Corrosion
Fatigue
fluid medium & short abrasion furrows.
Presence of metal corrosion products.
Rough pits or depression.
Presence of surface or subsurface cracks Sharp & angular edges around pits.
Seizure, catering rough & torn out
accompanied by pits & spalls
Hence taking the importance of composites & specifically polymer reinforced composite
we prepare a rice husk ceramic composite using rice husk ash & epoxy resin. The
composites are to be prepared with different volume fraction of the filler i.e rice husk ash.
The rate of wear is to be measured at varying load on a Pin-on-Disc apparatus.
Keeping all this in view the entire work has been divided into five chapters.
In the second chapter overview of the fabrication methods and work related to
present investigations available in literatures are presented.
The third chapter represents the experimental methods employed to get the
results.
In the fourth chapter we enumerated the results & discussed the conclusions &
results we received during our experimental procedure.
23
CHAPTER – 2
2. 1
LITERATURE SURVEY
The literature survey was carried out as a part of the thesis work to get an
overview of the production processes & properties of a polymer matrix composite. As the data
on the service lives of composite structures is becoming gradually known, it can be said that they
are more durable, maintain dimensional integrity, resist fatigue loading and are easily
maintainable and repairable.
In recent years, natural fibers have drawn worldwide attention on a potential reinforcement
material for the composite material. Usually the fiber reinforcement is done to obtain high
strength and modulus. Hence it is necessary for the fibers to possess higher modulus. Then the
matrix material, so that load is transferred to the fiber from the matrix effectively. Natural fiber
to the maximum extent fulfills these criteria. And Rice Husk is one of such natural fiber. The RH
Ash is the filler material that is got by carburizing the rice husk at 900degree Celsius.
Prasad BK et.al [7] while trying to find out the factors that control the abrasive wear of the zinc
based alloy Silicon Carbide particles composites have reported that when silicon carbide from
RHA is high enough to match the requirements. They also report that the Silicon Carbide can be
either directly used as abrasive material or hot pressed with as abrasive material or hot pressed
with composites.
The application of RHA [8-10] as a filler in plastics is relatively limited mainly to polypropylene
(PP). As reported with an increase in the RHA loading, a PP composite flexural modulus &
density increases, where as its tensile strength; breaking elongation & impact strength decreases;
yet RHA still can replace some commercial fillers.
Navin Chand et. al [11] reports that the study on polyester filled with RHA. Their report says
that both the tensile & impart strength of the resulting composites, decreases with increasing
filler loading.
24
It is also reported that [12, 13] in addition to being used in rubber or plastics, RHA can also be
used as a filler rubber/plastic blends.
Rozman H.D. et. al [14] studied the effects of chemical modifications of rice husk & reports that
with chemical modification the reinforcing effects can be increased to an acceptable limit.
Abrasive wear performance in natural fiber reinforced polymer composites is very important
aspect to exploit their usage in many applications. Chand et. al 1994 [15] have reported a new
theory for abrasive wear mechanism for FRP composites.
After reviewing the literature available on rice husk it is clear that the interfacial bond
between the reinforcing fiber and the resin matrix is important to realize the mechanical
properties of the composite. Also, to obtain desired properties from a composite material,
reinforcement and filler are added for polymer materials. Any additional improvement in
mechanical and tribological properties is attained by filling particulate matters. The resistance of
epoxy and polyester resin to crack propagation are relatively low. Fracture properties of epoxy
resin can be improved by addition of other materials. Filler affects the mechanical properties
according to their packing characteristics, size and interfacial bonding. It is also shown by some
researchers that the fracture toughness of epoxy resin could be improved by addition of fly ash
particles as fillers in glass-epoxy composite.
Hence the priority of this work is to develop a polymer matrix composite with rice husk
ash as filler/fiber in epoxy matrix. The composite prepared will then be subjected to wear test.
2.2
MATERIAL SELECTION
2.2.1 Matrix Material
The matrix alloy should be chosen only after giving careful consideration to its
chemical compatibility with the reinforcement and its own characteristics properties.
2.2.2
Why Polymer Matrix Selection?
25
Polymers are structurally more complex than metals or ceramic. They are cheap
and easily processed. But polymers have lower strength and modulus and lower temperature use
limits. Prolonged exposure to UV light and some solvents cause the degradation of polymer
properties. Because of predominantly covalent bonding, polymers are poor conductors of heat
and electricity. Polymers, however, are resistant to chemicals than metals. Polymers are giant
chainlike molecules (hence the name macromolecules) with covalently bonded carbon atoms
forms the backbone of the chain. The process of macromolecules formation from small ones is
called polymerization; i.e, it is the process of joining many monomers, together to form polymer.
Polymers used to manufacture advanced PMCs are of two types thermoset and thermoplastics
resins.
a) Thermoset resins
Thermoset resins dominate the advanced composites industry, while thermoplastics have
only a minor role. It requires addition of a hardener and impregnation onto a reinforcing
material, followed by a curing step to produce a finished part. Some of the common thermoset
resins are described briefly here.
Epoxy resins are relatively low molecular weight monomers with low shrinkage during
cure. They can be partially cured and stored in that state. These cured epoxy resins have high
chemical and corrosion resistance, good mechanical and thermal properties. But, they are more
expensive compared to polyester resins. The second of the essential ingredients of an advanced
composite system is the hardener. These compounds are very important because they control the
rate of the reaction and determine the performance characteristics of the finished product. Since
these compounds are catalysts for the reaction, they must contain active sites on their molecules.
Some of the commonly used hardener in the advanced composites is the aromatic amines like 4.4
methylene-dianiline (MDA) and 4.4-sulfonylianiline (DDS)
b) Thermoplastic resins
Thermoplastics resins require only heat and pressure to form a finished product. Unlike
thermoset resins, the thermoplastics resins can be reheated and reformed into another shape, if
desired. Common examples include polyethylene, polystyrene, nylon, polycarbonate,
polysulfone, polyphenylene sulfine etc. Polyamides, Polyimide, PEEK are relatively new
26
composite industry and are used in high temperature applications. These resins have better
thermal stability and flame resistance than the epoxy resins. Polyamide based composites have
excellent strength retention in hot and wet environment but they are brittle and have a very low
elongation at break.
2.2.3 Reinforcement
Reinforcement increases the strength, stiffness and the temperature resistance and lowers the
density of PMC. In order to achieve these properties the selection depends upon the type of
reinforcement, its method of production and chemical compatibility with the matrix and the
following aspects should be considered while selecting the reinforcement material.
•
Size – diameter and aspect ratio(L/D)
•
Shape – Chopped fiber, whisker, spherical or irregular particulates, flakes, etc:
•
Surface morphology – smooth or corrugated and rough:
•
Poly or single crystal
•
Structural defects – voids, occluded material,
•
Surface chemistry
•
Material Impurities
•
Inherent properties – strength, modulus and density.
2.2.4 Reinforcement Materials
Fibers as reinforcing material offer two advantages. Firstly, the bulk material is always
stronger when produced as small diameter fibers due to the exclusion of large scale defects.
Secondly, the fiber configuration allows tailoring of properties in specific directions. Fibers are
added to the resin system to give strength to the finished part. The selection of reinforcing
material is based upon the properties desired in the finished product. Fibers used in advanced
composite manufacture come from various forms, such as yarns, roving, chopped strands, woven
fabric and mats.
27
2.3 FABRICATION METHODS OF PMCs
There are two general divisions of composites manufacturing processes: open molding
and closed molding. With open molding, the gel coat and laminate are exposed to the
atmosphere during the fabrication process. In closed molding, the composite is processed in a
two-part mold set, or within a vacuum bag. There are a variety of processing methods within the
open and closed molding categories:
a) Open Molding Method: Hand Lay-Up, Spray-Up, Filament Winding
b) Closed Molding Method:
Compression molding, Pultrusion, Vacuum Bag Molding,
Vacuum Infusion Processing, Resin Transfer Molding (RTM)
2.3.1 Open Molding
Open molding process saturates fiber reinforcement with resin, using manual rollout
techniques to consolidate the laminate and removing the entrapped air. A major factor of the
operation is the transfer of resin from a drum or storage tanks to the mold. The means used to
transport the resin, in many cases, characterizes the specific process method.
a) Hand Lay –Up
Hand lay-up is suitable for making a wide variety of composites products including:
boats, tanks bath ware, truck/auto components, architectural products and many other products
ranging from very small to very large. Production volume is low; however, it is feasible to
produce substantial production quantities using multiple molds. Simple, single-cavity molds of
fiberglass composites construction are generally used. Molds can range from very small to very
large and are low cost in the spectrum of soft composites molds.
Gel coat is applied to the mold using a spray gun for a high-quality surface. When the gel
coat has cured, roll stock fiberglass reinforcement is manually placed on the mold. The
lamination resin is applied by pouring, brushing, or using a paint roller. FRP rollers, paint rollers,
28
or squeegees are used to consolidate the laminate, wetting the reinforcement, and removing
entrapped air. Subsequent layers of fiberglass reinforcement are added to build laminate
thickness (Fig 2.1).
Simplest method offering low-cost tooling, simple processing and wide range of part
sizes are the major advantages of this process. Design changes are readily made. There is a
minimum investment in equipment. With skilled operators, good production rates consistent
quality is obtainable.
Fig 2.1 Hand Lay-Up Technique
29
CHAPTER – 3
3. MATERIALS AND METHODS
3.1
RAW MATERIALS
Raw materials used in this experimental work are listed below:
1. Rice Husk
2. Epoxy resin
3. Hardener
3.1.1 Rice Husk
Rice husk is an agricultural waste material abundantly available in all most all over the
world. They are the natural sheaths that formed on rice grains during their growth. Removal
during the refining of paddy, these husks have no commercial interest. But in some places they
may be used as fuels although they have very low calorific value. The annual rice husk
production in India amounts is generally approximately 3 million tons [16]. World wide
production of rice husk is about 120 million tons per year. That makes the rice husk one of the
largest readily available but also one of the most under-utilized resources. Increase in the
environmental awareness has led to a growing interest in researching ways of an effective
utilization of rice by-product, from which rice husk is particularly valuable due to its high
content of amorphous silica. The rice husk contains 80 percent organic volatile materials and
remaining 20 percent silica. The rice husk ash (RHA) contains 85%-95% amorphous silica [17].
Silica obtained is quiet reactive & depends upon factors like the degree of firing and is used for
making insulating materials, refractory bricks [18, 19], Portland cement, masonry cement and
pottery ware. It is used as filler materials in paints and in fertilizers [20] etc. rice husk ash has
also been used in aluminum alloy for increasing abrasion resistance. The chemical composition
of the rice husk ash varies from sample to sample which may be due to the different geographical
conditions, type of paddy, climatic conditions and type of fertilizer used.
It was found that RH Ceramics contains amorphous silica in addition to amorphous
carbon as the main constituents. Compared to the conventional sources of silica rice husk ash as
a ceramic raw material possess advantages like fine particles size and higher reactivity due to its
amorphous nature. Many authors have concluded that rice husk is an excellent source of high
30
grade amorphous silica. Accordingly silica is used in different industries and products like rubber
industry as a reinforcing agent, in tooth pastes as a cleaning agent, as an anti-caking agent in
salts, in cosmetics etc.
But it is interesting to note that rice husk contains 20% ash, 22% lignin, 38% cellulose, 18%
pentosans and 2% moisture. A typical composition of ash is [18] 95% SiO2, 2% K2O, 1% CaO,
P2O5 & Na2O3, Fe2O3 & MgO. The silica in rice husk originally is present in amorphous form
but after carburizing it becomes crystalline.
In this work the new hard porous carbon material called the RH (rice husk) Ceramic has been
developed and the tribological properties of the RH Ceramic Epoxy Composite has been studied
using a pin-on-disc machine.
3.1.2 Epoxy resin
ARALDITE(LY 556) Standard Epoxy Adhesive was used as the resin having the following
outstanding properties has been used as the matrix material.
a. Excellent adhesion to different materials.
b. High resistance to chemical and atmospheric attack.
c. High dimensional stability.
d. Free from internal stresses.
e. Excellent mechanical and electrical properties.
f. Odorless, tasteless and completely nontoxic.
g. Negligible shrinkage.
3.1.3
Hardener
In the present work hardener (HY951) is used. This has a viscosity of 10-20 MPa at 25ºc.
3.2 PREPARATION OF COMPOSITES:
The following procedure has been adopted for the preparation of the specimen.
(a) Rice Husk Ceramic filler Preparation
Finely milled rice husk was collected from a local rice mill. The milled rice husk contains
many impurities like dust, small rice particles, and fine sand particles. These impurities need to
31
be cleaned so as we get pure rice husk. For this purpose we wash the rice husk thoroughly with
water. Care is taken so as the rice husk is not washed out in this process. This kind of wash
removes major impurities like sand particles or dust particles & small rice particles remained.
After it is washed thoroughly we dry them up in a desiccators or in the sun. The husk is
thoroughly dried so as no amount of moisture remains in this process. Then to again separate out
larger husk particles & remained amount of rice particles we sieve the rice husk thoroughly.
Finally the husk is ready to be carburized. For our experimental process we used Nitrogen
atmosphere (N2) & we carry out the carburizing process in the nitrogen atmosphere. For this we
used a furnace & to ensure uninterrupted supply of nitrogen we used a nitrogen generator. Now
the dried rice husk is placed in small porcelain crucibles & put into the furnace chamber. The
nitrogen generator is attached. The furnace is an automated one so we fix the step with which the
temperature will increase. We start with a furnace temperature of 300°C & gradually go up to
900°C in a step function of 5°C each minute. Hence the furnace takes 120 min to heat up to the
required temperature .At the same temperature of 900°C it is maintained for 4 hours. This
ensures that rice husk is properly turned into ash. Then the furnace is turned off & allowed to
cool .It takes around 3 hours to cool. After it is sufficiently cooled the furnace chamber is opened
& then the rice husk is taken out & kept in a sealed envelope so that it doesn’t come in contact of
atmosphere. Some important points to remember while carburizing the husk is, Nitrogen
atmosphere while carburizing should take place in 99% Nitrogen atmosphere otherwise the ash
may undergo oxidation & perfect vacuum should be maintained before the start of the process.
The amount of ash to be collected or required for the experiment is calculated by the % of
volume fraction technique whose tabulation & calculation is shown in the subsequent pages.
(b) Composite preparation
After the filler material is prepared the resin for preparation of the composite is carefully
choosen. Now we prepare composites with varying degrees of filler & resin percentage (i.e. 10%
filler & 90% resins, 15% filler & 85% resins, 20% filler & 80% resins, 25% filler & 75% resins,
30% filler & 70% resins). The required weights of filler & polymer or resin for this purpose are
calculated as shown in the calculation part.
Now the resin & filler is mixed & it is then put into a box jig to form cylindrical components of
3.5 cm long & 10 mm diameter. Load is applied upon it & it is left for 48-72 hours to form solid
32
cylindrical components. After 48-72 hours the components are taken out & placed in a sealed
envelope.
Then the percentage of voids is calculated using the void fraction calculation formula which is
shown in the calculation part.
After preparation of the composite & the cylindrucal components the components are put to wear
test. This test is performed on a pin on disc apparatus. The apparatus specifications & the
experimental methodology are discussed below.
3.3 WEAR TEST:--
Fig 3.1: Set up to perform an Abrasive wear test on a pin on the disc
33
a.) Pin on Disc type Tribometer Friction & Wear Machine
The Tribometer uses a pin-on-disk system to measure wear. The unit consists of a gimbaled arm
to which the pin is attached, a fixture which accommodates disks up to 165 mm in diameter & 8
mm thick, an electronic force sensor for measuring the friction force, and a computer software
(on Lab view platform) for displaying the parameters, printing, or storing data for analysis. The
motor driven turntable produces up to 3000 rpm. Wear is quantified by measuring the wear
groove with a profilometer (to be ordered separately) and measuring the amount of material
removed. Users simply specify the turntable speed, the load, and any other desired test variables
such as friction limit and number of rotations.
Fig 3.2 Specimen (composite) loaded as pin for performing wear test
34
Designed for unattended use, a user need only place the test material into turntable fixture and
specify the test variables. A pre-determined Hertzian pressure is automatically applied to the pin
using a system of weights. Rotating the turntable while applying this force to the pin includes
sliding wear as well as a friction force. Since pins can be fabricated from a wide range of
materials virtually any combination of metal, glass, plastic, composite, or ceramic substrates can
be tested.
Software included with this model provides for quick calculation of the Hertzian pressure
between the pin and disk. The cup-like (housing) enclosed fixture permits the use of liquid
lubricants during a wear test (optionally).
b.) Features & specifications
Table 3.1: Specification of the pin-on-disc apparatus
Rotational Speed
Diameter of Track
Load Range
Loading Lever Ratio
Disc Type
Pin Size
Software
Wear or Displacement
Frictional Force
Drive
Motor Control
Power
Up to 200 rpm
40 mm to 118 mm
Up to 200 N
1:1 ratio
Diameter = 120 mm ; Thickness = 8mm
6 mm-12 mm
MAGVIEW – 2007
-2000 microns to + 2000 microns
Up to 200 N
1.1 KW D.C. motor, constant torque
Thyrister converter, with motor protection
230 Volt Line, 15 amps, single phase, 50 Hz. A.C.
c.) Data Acquisition
The friction coefficient signal is displayed in real time on a PC Screen. Data can be viewed as it is
logged for the entire specified test duration, which can be recalled later for detailed analysis. The
software allows 9 different logged test files for on-line analysis / mapping the software displays the
test time, turn count, linear velocity, and user-defined test parameters. This data can be stored and
printed along with the friction traces.
Purpose
35
Records friction and wear in sliding contact in dry, lubricated, controlled environment and partial
vacuum.
d.) Application
Fundamental wear studies. Wear map ping and PV diagrams. Friction and wear testing of metals,
ceramics, soft and hard coatings, plastics, polymers and composites, lubricants, cutting fluids, heat
processed samples.
Features
•
Displays and records friction, wear and pin temperature (optional).
•
Dry, lubricated, controlled environment and vacuum tests (optional).
•
Wide sliding speed range (continuously variable thru the variable drive)
•
User can program RAMP tests to be specified by the user (available optionally)
Standards
ASTM G-99
Instrumentation and Data Acquisition System for the measurement of
•
•
•
•
•
RPM
Wear
Frictional force
Temperature
Electrical Contact resistance measurement (40 mV Signal)
PC acquires data online and displays it in several ways. Graphs of individual tests can be printed.
Results of different tests can be superimposed for comparative viewing. Data can be exported to
other software.
•
Tests at ambient temperature
•
Dead weight loading
•
Electrical contact resistance measurement
•
Displays Load, Friction, temp, rpm / speed on the display panel
•
Auto on/off (timer)
36
3.4 STANDARD METHODOLOGY TO CONDUCT THE WEAR TEST
The amount of wear in any system will, in general, depend upon the number of system factors
such as the applied load, machine characteristics, sliding speed, sliding distance, the
environment, and the material properties. The value of any wear test method lies in predicting
the relative ranking of material combinations. Since the pin-on-disk test method does not attempt
to duplicate all the conditions that may be experienced in service (for example; lubrication, load,
pressure, contact geometry, removal of wear debris, and presence of corrosive environment),
there is no insurance that the test will predict the wear rate of a given material under conditions
differing from those in the test.
FIG. 3.3 Schematic of pin-on-disk wears test system.
Note—F is the normal force on the pin, d is the pin or ball diameter, D is the disk diameter, R is
the wear track radius, and w is the rotation velocity of the disk.
a.) Scope of the experimental setup
1.) This test method covers a laboratory procedure for determining the wear of
materials during sliding using a pin-on-disk apparatus. Materials are tested in pairs under
nominally non-abrasive conditions. The principal areas of experimental attention in using
this type of apparatus to measure wear are described. The coefficient of friction may also
be determined.
2.) The values stated in SI units are to be regarded as standard.
37
3.5 EXPERIMENTAL PROCEDURE
1.) First of all the pin or the sample is mounted on to the arm of the triobometer.
2.) Then the desired load is applied on to the pin by a pulley arrangement. The loads vary
from 5N, 10N, 15N & 20N.
3.) First of all 5N load is added & the 10% sample component is loaded as the pin.
4.) A velocity is selected to be given to the disc. A motor is supplied with electric power
which transmits the energy into rotary motion of the disc. Initially 30 rpm (0.157m/s) is
chosen & the disc is made to rotate at that speed for 300 sec.
5.) The friction & temperature rise is recorded by the electronic data accusation system.
6.) The test is run for 4 times for each sample. The average value of coefficient of friction is
computed from the data. And after each run the weight loss is measured using a weighing
machine.
7.) The weight loss for each run is computed by getting the difference between the initial
weight & the final weight. Then the average weight loss is got after 4 runs are completed.
8.) Then with the same load & 15%, 20%, 25% & 30% filler component we repeat the same
procedure & get the weight loss.
9.) After that we change the load to 10N & again run the experiment with the components
with varying filler %age keeping the velocity constant.
10.) Finally the weight loss is tabulated as shown below.
11.) From the weight loss we can get the wear rate & the specific wear rate by using the
formula.
From the experiment we get 2 important data i.e. the weight loss or wear in a specific time
& the coefficient of friction for the velocity of 30 rpm or 0.157m/s
38
CHAPTER – 4
4.1 CALCULATIONS:-Table 4.1:-- Calculation of weight of filler & polymer required for making the composite
Sl.no
Volume of
composite
% of
Filler
(Vc)
Volume of Volume of
Density
Density
Weight
Weight
filler(Vf)
Polymer
of filler
of
of filler
of
(in cc)
(Vp)
(in
Polyme
(in gm)
polymer
(in cc)
gm/cc)
r (in
.5665
2.7225
(in gm)
1
2.75
10
.275
2.475
2.06
gm/cc)
1.1
2
2.75
15
.4125
2.3375
2.06
1.1
.84975
2.57125
3
2.75
20
.55
2.2
2.06
1.1
1.133
2.42
4
2.75
25
.6875
2.0625
2.06
1.1
1.41625
2.26875
5
2.75
30
.825
1.925
2.06
1.1
1.6995
2.1175
Table 4.2:-- Calculation of the total weight required being required
Total samples for Sl.no 1-5
Total weight of filler
(8*weight of the filler)
Total weight of the polymer
(8*weight of the polymer)
8
4.532
21.78
8
6.798
20.57
8
9.064
19.36
8
11.33
18.15
8
13.596
16.94
Total nos. of samples: 40
Total Weight:-- 45.32 gms
Total weight:-- 96.8 gms
39
For void calculation:-Density of polymer=1.0974 gm/cc
Density of Fiber=2.25 gm/cc
Theoretical Density= T
Experimental density =M
T = 100/[(R/D)+(r/d)] where:-R = % of Resin
D = Density of Resin
r = % of Fiber
d = Density of Fiber
Table 4.3:-- Calculation of Theoretical Density (T)
% of Fiber
Density of
Resin (in
gm/cc)
Density of
fiber (in
gm/cc)
Theoretical Density=
T (in gm/cc)
90
10
1.1
2.25
1.159
85
15
1.1
2.25
1.191
80
20
1.1
2.25
1.225
75
25
1.1
2.25
1.261
70
30
1.1
2.25
1.299
% of
Resin
Table 4.4:-- Calculation of void percentage
Voids content V=100(T - M)/T
% of fiber
T (in gm/cc)
M (in gm/cc)
T-M(in gm/cc)
V (in %age)
10
1.159
1.143
0.016
1.402
15
1.191
1.171
0.020
1.737
20
1.225
1.201
0.024
2.019
25
1.261
1.229
0.032
2.616
30
1.299
1.262
0.037
2.949
40
Fig 4.1:-- Plot of percentage of filler vs measured density (M)
41
4.2 TEST RESULT
a.) The Coefficient of Friction
Table 4.5:-- The value of coefficient of friction vs. time when various sample underwent the
wear test for 300 seconds at a velocity of 0.157 m/s.
Sl.no
1
2
3
4
5
6
7
8
9
70
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
TIME(in sec)
1.229
5.354
10.526
15.698
20.869
26.041
31.198
36.369
41.526
46.698
51.854
57.026
62.198
67.354
72.526
77.698
82.854
88.01
93.182
98.354
103.51
108.682
113.838
119.01
124.182
129.338
134.51
139.666
144.838
149.994
155.166
160.338
165.494
170.666
175.838
180.994
186.166
191.323
196.494
201.666
206.823
10%
0.078
0.361
0.597
0.741
0.834
0.891
0.927
0.95
0.963
0.97
0.974
0.973
0.972
0.972
0.972
0.971
0.971
0.97
0.967
0.967
0.966
0.965
0.963
0.96
0.959
0.955
0.954
0.953
0.952
0.95
0.949
0.947
0.945
0.946
0.944
0.944
0.944
0.945
0.945
0.945
0.945
15%
0.085
0.371
0.61
0.757
0.844
0.898
0.932
0.955
0.971
0.977
0.985
0.993
0.997
1
1.005
1.007
1.007
1.006
1.008
1.007
1.006
1.004
0.999
0.997
0.99
0.988
0.986
0.981
0.982
0.982
0.979
0.98
0.977
0.977
0.978
0.974
0.973
0.97
0.969
0.97
0.971
42
20%
0.081
0.352
0.58
0.728
0.824
0.884
0.922
0.946
0.962
0.974
0.981
0.985
0.987
0.984
0.982
0.984
0.988
0.992
0.996
0.999
0.997
0.994
0.989
0.986
0.985
0.987
0.991
0.993
0.992
0.992
0.993
0.995
0.999
1.001
1.002
1
0.996
0.993
0.991
0.99
0.993
25%
0.087
0.369
0.6
0.742
0.833
0.889
0.926
0.947
0.962
0.974
0.982
0.99
0.993
0.998
1.002
1.006
1.01
1.014
1.017
1.022
1.024
1.026
1.028
1.03
1.031
1.028
1.027
1.026
1.024
1.025
1.024
1.023
1.022
1.019
1.016
1.013
1.011
1.011
1.009
1.008
1.007
30%
0.082
0.353
0.57
0.707
0.794
0.85
0.885
0.91
0.927
0.94
0.95
0.958
0.963
0.969
0.973
0.977
0.981
0.983
0.985
0.988
0.988
0.989
0.99
0.991
0.994
0.997
0.999
0.998
0.995
0.995
0.997
0.998
0.998
0.999
1
1.001
1.002
1
1.001
1.001
1.001
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
212.01
217.166
222.338
227.494
232.666
237.823
242.994
248.151
253.323
258.479
263.651
268.807
273.979
279.135
284.307
289.463
294.666
299.823
0.944
0.945
0.945
0.944
0.943
0.946
0.946
0.947
0.949
0.948
0.949
0.95
0.95
0.95
0.95
0.952
0.951
0.952
0.975
0.975
0.973
0.974
0.971
0.97
0.966
0.964
0.966
0.963
0.963
0.961
0.957
0.955
0.949
0.948
0.947
0.947
0.996
0.998
0.998
1
1.005
1.007
1.007
1.007
1.007
1.002
0.998
0.993
0.991
0.991
0.991
0.997
1.003
1.004
1.006
1.004
1.004
1.003
1.003
1.002
1.002
0.999
0.996
0.992
0.991
0.99
0.991
0.991
0.992
0.993
0.994
0.993
Fig 4.2 Plot of COF (y-axis) vs. Time (x-axis)
43
0.998
0.998
1.001
1.001
1.001
1
0.999
0.997
0.996
0.996
0.996
0.996
0.994
0.994
0.994
0.993
0.993
0.993
a.) The determination of weight loss:-Table 4.6:-- Weight Loss (in gm) during wear test in 300 seconds:
V=0.157 m/s
Load (in N)
10% filler
15% filler
20% filler
25% filler
30% filler
5
.08
.07
.06
.05
.04
10
.13
.12
.1
.08
.06
15
.2
.16
.14
.12
.09
20
.26
.22
.18
.17
.14
Fig 4.3:-- Plot of weight loss vs. Load for each sample
44
a.) To find dimension less wear rate:--
Dimensionless wear rate = W= (M1-M2)/ (ρ.A.v.t)
For all samples:Area (A) = 3.14
Density (ρ) = Experimental density: we get the values from table 2
V = 31.4 cm/s &
Time = 1200 seconds
L = V*Time = 37680cc/sec in each case
Table 4.7: -- Dimensionless wear rate under varying loads for various composites.
Sl.No Load(N) W for 10%
W for 15%
W for 20%
W for 25%
W for 30%
1.
5
1.26E-06
1.01E-06
9.14E-07
6.87E-07
5.35E-07
2.
10
2.22E-06
1.66E-06
1.48E-06
1.24E-06
8.03E-07
3.
15
2.88E-06
2.52E-06
2.11E-06
1.65E-06
1.2E-06
4.
20
4.51E-06
3.46E-06
2.88E-06
2.47E-06
1.61E-06
Fig 4.4:-- Plot of Dimensionless Wear rate vs. Load for each sample
45
a.) Detemaination of Specific wear rate :-Specific wear rate =k0 = w/ (ρ x D x L)
Where w = the weight loss from table 5 at velocity of 0.157 m/s
ρ = the measured density of the sample which we get from table 2 = M
D = Diameter of the Sample = 10 mm
L = Traveling distance
For 20N load the specific wear is shown in the table:-Table 4.8: -- Specific wear rate (K0) of the sample under load of 20N & velocity of 0.157 m/s
Sl.no Distance in m 10% filler
15% filler
20% filler
25% filler
30% filler
1.
94.25
1.21E-10
9.51E-11
7.95E-11
6.91E-11
4.2E-11
2.
188.5
7.89E-11
6.34E-11
5.3E-11
4.75E-11
3.36E-11
3.
282.75
4.64E-11
3.62E-11
3.09E-11
2.59E-11
1.68E-11
4.
377
3.71E-11
2.27E-11
1.77E-11
1.29E-11
8.41E-12
Fig 4.5:-- Plot of specific wear rate vs. sliding distance (in m)
46
For 5N load the specific wear is shown in the table:-Table 4.9: -- Specific wear rate (K0) of the sample under load of 20N & velocity of 0.157 m/s
Sl.no Distance in m 10% filler
15% filler
20% filler
25% filler
30% filler
1.
94.25
6.03E-11
4.98E-11
3.98E-11
3.45E-11
2.94E-11
2.
188.5
3.71E-11
3.17E-11
2.65E-11
2.16E-11
1.68E-11
3.
282.75
1.86E-11
1.36E-11
8.83E-12
1.29E-11
8.41E-12
4.
377
4.64E-12
4.53E-12
4.42E-12
4.32E-12
4.20E-12
Fig 4.6:-- Plot of specific wear rate vs. sliding distance (in m)
47
CHAPTER – 5
5.1
CONCLUSIONS
The following conclusions are drawn from the above studies.
1.) There is an increase in the percentage of voids in the composite when the percentage of
filler i.e. the rice husk ash in the composite increases.(table 4.4)
2.) The coefficient of friction almost remains constant for a particular matrix constituent, for
the whole of the test period as it is clear from the table 4.5.
3.) With increase in the percentage of fiber i.e. the rice husk ash in the composite the wear
rate decreases even though the other environment variables remaining same. (Table 4.6)
4.) For a given composite with a defined constituent of fiber & matrix the wear rate increases
due to increase in the Load. (Table 4.6)
5.) The dimensionless wear rate decreases with the increase of filler or rice husk ash in the
composite & with increase in load for a particular composite increase with increase in
load. (table 4.7)
6.) The specific wear rate decreases with the increase of filler or rice husk ash in the
composite & with increase in load for a particular composite increase with increase in
load. (table 4.8)
48
RECOMMENDATION FOR FURTHER RESEARCH
From this work, it is observed that the wear rate decreases with increase of filler
percentage i.e. rice husk in the composite & also the wear rate increases in the load. We did the
experiment for a single velocity. This can be extended to other types of lay out.
1.
The observation of wear rate can be noted with increase & decrease of velocity of the
disc in pin-on-disc.
2.
The rice husk was carburized at 900°C. But the wear behavior of the rice husk can be
studied by increasing the temperature at which the carburizing takes pale e.g. 1200°C
& 1400°C.
3.
Mechanical Tests like tensile & compressive, three point bend test etc. can also be
performed upon the composite material of variable constituents we synthesized & can
be studied to get its mechanical properties.
********
49
REFERENCES
[1] Jartiz, A.E., Design 1965, p.18
[2] Kelly, A. Sci. American 217, (B), (1967): p. 161.
[3] Berghezan,A.Nucleus,8(5),1966,(Nucleus A Editeur,1,rhe,Chalgrin,Paris, 16(e).
[4] Suchetclan Van, Philips Res. Repts. Volume 27, (1972): p. 28.
[5] Agarwal B.D. and Broutman L.J., “Analysis and performance of fiber composites” John
Wiley & Sons, New York, (1980): p. 3-12.
[6]
Burwel J.T & Stang C.D ,”Metalic Wear”, Proc. Soc (London) , 212 A Amy
1953, pp 470-477.
[7] –Prasad .B.K. , Das .S., Jha.A.K., Modi.O.P., Dasgupta.R., Yegneswaran.A.H.
Compos. Part A: Appl. Sci. MAnuf. 1997,28,30
[8] –Faud.M.A.Y.,Jamaludin,M.,Ishak, Z.A.M.,Omar.A.K.M. Int J. Polym.mater.
1993,19,75
[9] – Faud.M.A.Y.,Jamaludin,M.,Ishak, Z.A.M.,Omar.A.K.M. Poly J. 1995,27,1002
[10] – Faud.M.A.Y.,Jamaludin,M.,Ishak, Z.A.M.,Omar.A.K.M. Polym. J.1995, 3I,885
[11] –Chand.N., Dan T.K., Verma.S.,Rohatogi.P.K., J. Mater. Sci. Lett. 1987.6,733
[12] –Siriwardena.S., Ismail.H., Isaku.U.S. Polym. Test. 2000,20,105
[13] -- Ismail.H., Nizam.J.M., Khalil. H.P.S.A. Polym. Test. 2001. 20,125.
[14] - Rozman H.D., Lee.M.H., Kumar.R.N., Abusamah.A., Ishak.Z.A.M. J. Wood Chem.,
Technol.2000,20.93.
50
[15] Navin Chand, B. Majumdar & M Fahim., Indian J. of Engg. & Material Science
(1994) 273-278
[16] V. M. H. Govindrao , JSIR 39 (1980) 495
[17] E.A. Huppertz , Chem. Abs. 82 (1975) 78839t
[18] A. E. Chittenden & Flaws, Trop. Sci. (1964) 187
[19] R. Mc. Daviel, Rice J. 49 (12) (1946) 14
[20] G. R. Rao & P.K. Rohatgi, J. Mater. Sci., submitted.
51
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