ABSTRACT
This research was conducted to produce asbestosfree automobile disk brake pads using eco-friendly; Periwinkle and Fan palm shells materials. The use of asbestos fiber is being avoided due to its carcinogenic nature that might cause health risks. A new brake pad was produced using agro waste materials (periwinkle shell and fan palmshells)with thermoset resin as a binder to replace asbestos with thermoset as a binder. Two sets of brake pad composites were produced using periwinkleshell and fan palm particles by varying the particlesizes from 125μm to 710μm. The morphology, physical, mechanical and wear properties of the brakepads werestudied. The mechanical properties upon addition of the agro waste improved. Theresults showed that the uniform distribution of the periwinkle shell and the fan palm particles in the microstructure of the brake pad composites is the major factor responsible for the improvement in themechanical properties,though the periwinkle shell pad had better properties. Taguchi technique was used to arrive at 65 % periwinkle or fan palm and 35 % resin as the optimal formulation, with thecorresponding manufacturing parameters as; (moulding pressure41 Kpa, moulding temperature 150 ºC, curing time 10 mins, and heat treatment time1hr.).Design expert software 6.0.8 was employed to on investigate the effect of particle size, speed, temperature and load the coefficient of friction. The design expert analysisshowed thatthe particle size, speed, temperature, loadshave significanteffect on friction coefficient.Brake pads developed from 125μm formulation for both periwinklesand fanpalm shell particlesexhibited better thermal and mechanical properties than those of fan palm shells andcompared favourably with that of commercial brake pad. Hence this research indicates that both periwinkles shell and fan palm particles can be effectively used as replacement for asbestosin the development of automobile disk brake padindicating 14.28%, 15.5 %, and 33.63 % increase in coefficient of friction, hardness, and compressive strength respectively than that of Mercedes Benz 230E salon car.
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TABLE OF CONTENTS
Cover Page – – – – – – – – – i Title Page- – – – – – – – – – ii Declaration- – – – – – – – – – iii Certification- – – – – – – – – – iv Acknowledgements- – – – – – – – – v Abstract- – – – – – – – – – vi Table of Contents- – – – – – – – – vii List of Figures- – – – – – – – – xii List of Tables- – – – – – – – – – xvi List of Plates- – – – – – – – – – xix Nomenclature– – – – – – – – – xx Chapter One- – – – – – – – – – 1
1.0 INTRODUCTION- – – – – – – – 1
1.1 BACKGROUND OF THE STUDY – – – – – 1 1.1.1 Periwinkle Shells- – – – – – – – 3 1.1.2 Fan Palm (hyphaenePetesiana)- – – – – – 4 1.2 STATEMENT OF THE PROBLEM- – – – – 5 1.3 THE PRESENT RESEARCH- – – – – – 5 1.4 AIM AND OBJECTIVES OF THE STUDY- – – – 6
1.5 SCOPE OF THE STUDY- – – – – – – 7
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1.6 SIGNIFICANCE OF THE STUDY- – – – – 7 Chapter Two- – – – – – – – – – 9 2.0. LITERATURE REVIEW- – – – – – – 9 2.1 HISTORICAL DEVELOPMENT OF BRAKES- – – – 9 2.1.1 Mechanically Operated Brakes- – – – – – 9 2.1.2 The Hydraulically Operated Four-Wheel Brake- – – – 11 2.1.3 Brakes with Internal Amplification- – – – – 12 2.1.4 Multi-Circuit Braking System- – – – – – 13 2.1.5 Full Power Brakes- – – – – – – – 13 2.2. BRAKE MATERIALS AND ADDITIVE FUNCTIONALITY- 14 2.2.1 Abrasives- – – – – – – – – 14 2.2.2 Friction Producers / Modifiers- – – – – – 15 2.2.3 Fillers, Reinforcements and Miscellaneous- – – – 16 2.2.4 Binder Resin (Matrix)- – – – – – – 17 2.3 REVIEW OF PAST WORKS- – – – – – 17 2.4 RESEARCH GAPS- – – – – – – – 28 Chapter Three- – – – – – – – – 29 3.0 MATERIALS AND METHOD- – – – – – 29 3.1 MATERIALS- – – – – – – – 29 3.2 EQUIPMENT- – – – – – – – 29 3.3 METHOD- – – – – – – – – 30
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3.3.1 Procedure for determining physical and mechanical properties of periwinkle and fan palm shells – – – – – – 30 3.3.2 Determination of the elemental composition of periwinkle and fan palm shells- – – – – – – – – – 30 3.3.3 Production of Periwinkle and Fan Palm Shells Powders- – – 31 3.3.4 Optimization of Brake Pad Formulation and Manufacturing Parameters- – – – – – – – – 32 3.3.5 Production of Brake Pad Samples- – – – – – 39 3.4. CHARACTERIZATION OF PERIWINKLE/FAN PALM PARTICLES- 40 3.4.1 X-ray Fluorescence (Xrf)- – – – – – – 40 3.4.2 X-ray Diffractograms(XRD)Analysis- – – – – 40 3.5 CHARACTERIZATION OF THE DEVELOPED BRAKE PAD- 41 3.5.1 Scanning Electron Microscope- – – – – – 41 3.5.2 Thermal Analysis- – – – – – – – 41 3.6 PHYSICAL AND MECHANICAL PROPERTIES- – – 42 3.6.1 Density- – – – – – – – – 42 3.6.2 Water and Oil Soak Test- – – – – – – 42 3.6.3 Hardness Test- – – – – – – – 43 3.6.4 Compressive Strength Test- – – – – – – 44 3.6.5 Wear and Friction test- – – – – – – 44 3.7 STATISTICAL DESIGN ANALYSIS AND DEVELOPMENT OF MATHEMATICAL MODEL FOR THE COEFFICIENT OF FRICTION PROCESS- – 45 3.7.1 Design expert 6.0.8- – – – – – – – 46 3.8 BRAKE PAD TEST RIG- – – – – – – 47 3.8.1 Selection of prime mover- – – – – – – 47
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3.8.2 Design of the fly wheel- – – – – – – 47 3.8.3 Selection of brake disc- – – – – – – 49 3.8.4 Shaft design- – – – – – – – – 49 3.8.5 Test rig load diagram- – – – – – – – 50 3.8.6 Bearing forces (RB and RE) – – – – – – – 50 3.8.7 Force induced by pulley- – – – – – – 51 3.8.8 Test rig bending moment diagram- – – – – – 51 3.8.9 Torsional moment- – – – – – – – 52 3.8.10 Frame Critical Bulking Load- – – – – – – 53 3.8.11 Selection of test rig pressure gauge- – – – – – 54 3.9 TEST RIG CONSTRUCTION PROCEDURE- – – – 54 3.10 LABORATORY BRAKE PAD TEST- – – – – 55 3.11 VEHICLE LIVE TEST- – – – – – – 57 Chapter Four- – – – – – – – – – 58 4.0 RESULTS AND DISCUSSION- – – – – – 58 4.1 CHARACTERIZATION OF PERIWINKLES/FAN PALM SHELL POWDER- – – – – – – – 58 4.2 DENSITY OF THE SAMPLES- – – – – – 62 4.3 SURFACE MORPHOLOGY- – – – – – 64 4.4 EFFECT OF PARTICLE SIZE ON THICKNESS SWELL IN WATER AND SAE OIL- – – – – – – – 67 4.5 THERMAL ANALYSIS- – – – – – – 69 4.6 HARDNESS VALUES- – – – – – – 78 4.7 COMPRESSIVE STRENGTH- – – – – – 79 4.8 WEAR CHARACTERISTICS OF DEVELOPED AND COMMERCIAL BRAKE PADS- – – – – – – – 81 4.9 FRICTION CHARACTERISTICS OF DEVELOPED AND COMMERCIAL BRAKE PADS- – – – – – 86
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4.10THE STATISTICAL DESIGN AND DEVELOPED MATHEMATICAL MODEL OF CO-EFFICIENT OF FRICTION OF THE DEVELOPED BRAKE PAD- – – – – – – – 91 4.11 VEHICLE LIFE TEST- – – – – – – 97 4.12 LABORATORY TEST- – – – – – – 98 4.13 COMPARISON OF RESULTS- – – – – – 102 Chapter Five- – – – – – – – – – 104 5.0 CONCLUSION AND RECOMMENDATIONS- – – – 104 5.1 CONCLUSION- – – – – – – – 104 5.2 CONTRIBUTIONTOKNOWLEDGE- – – – – 104 5.3 RECOMMENDATIONS- – – – – – – 105 REFERENCES- – – – – – – – – 106 APPENDICES- – – – – – – – – 113 PUBLICATIONS- – – – – – – – – 124
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CHAPTER ONE
INTRODUCTION
1.1 BACKGROUND OF THE STUDY
Brake pads are important part of braking systems for all types of vehicles that are equipped with disc brakes. They are considered as one of the key components for the overall performance of a vehicle and as heterogeneous materials, they are usually made from more than 10 ingredients. An ideal brake friction material should have constant coefficient of friction under various operating conditions such as applied loads, temperature, speeds, mode of braking and in dry or wet conditions so as to maintain the braking characteristics of a vehicle. In addition, it should also possess various desirable properties such as resistance to heat, low water and oil absorption, low wear rate and high thermal stability, exhibits low noise, and should not damage the brake disc.
According toAnderson (1992), brake pads are steel backing plates with friction material bound to the surface facing the brake discBrake pads convert the kinetic energy of the vehicle to thermal energy by friction. During the application of brake, friction between brake pads and rotating disc causes a vehicle to stop by converting kinetic energy of the vehicle into heat energy, with a transfer of smallamounts of friction material to the disc, (that is why a brake disk has dull grey colour).The brake rotor and disk (both now with friction material on), will then “stick” to each other to provide stopping power, and it is this action of friction material against the disk that is responsible for stopping the vehicle.
There are two types of brake systems, the disc and the drum. In disc brake applications, there are usually two brake pads per disc rotor, held in place and actuated by a caliper affixed to a wheel hub or suspension upright and are grouped into three viz: metallic, semi – metallic and organic.
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Generally, brake pad consists of a composition of reinforced fibers, binder, fillers, and friction additives. All these constituents are mixed or blended in varying composition and brake pad material is obtained using different manufacturing techniques. Reinforced fibers increase mechanical strength of the friction material,the binder maintains the brake pads structural integrity under mechanical and thermal stresses. It holds the components of a brake pad together and to prevent its constituents from crumbling apart. Fillers in a brake pad improve brake pad’s manufacturability as well as reduce the overall cost of the brake pad. Abrasives and lubricants are considered as friction additives; abrasives increase the friction coefficient, and remove iron oxides from the counter friction material as well as other undesirable surface films formed during braking. Lubricant stabilizes friction coefficient at high temperature. In addition to the function of these constituents, is the design of the brakes whichaffects heat flow, reliability and noise characteristics Chapman et al.,(1999)
In past years‟(1908 -1960’s), asbestos dominated the industry as the best friction material Blau (2001).Its content in vehicle brakes varies from 30%-70%. The positive characteristics of asbestos are thermal stability, and good strength and flexibility. But asbestos causes carcinogenic effects on human health.
Due to the increasing trend in the development of asbestos free brake pads, several research works have been carried out in the area of development of asbestos-free brake pads. The use of bagasse (Aigbodianet al., 2010), palm kernel shell Dagwa and Ibhadode (2006) and palm oil clinker (Zamriet al., 2011) have been investigated in order to replace the asbestos-free brake pad material. Current trend in the research field is the utilization of industrial or agricultural wastes as a source of raw materials for composite development (Leman et al., 2008). This will provide more economical benefit and also environmental preservation by utilizing the waste of natural fiber. Thus it is in line with this trend that this work based on the development of automobile disk
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brake pads using eco-friendly periwinkle shell and fan palm shell materials which are agricultural waste.
1.1.1 Periwinkle Shells
Periwinkle shell Plate 1.1 is a waste product generated from the consumption of a small greenish-blue marine snail periwinkle (littorea), housed in a V shaped spiral shell, found in many coastal communities within Nigeria and othertropical swampyregions of the world. The shell is a very strong, hard and brittle material. It is found in the lagoons and mudflats of the Niger Delta between Calabar in the South East and Badagry in the West of Nigeria. The edible part of periwinkle is eaten as sea food while the shell is disposed off as a waste, though few people utilize the shell as coarse aggregate in concrete in areas where neither stones and granite are not readily available for purposes such as; paving of water logged areas, for homes, soak-away, slabs and road construction. However, a large amount of these shells are still disposed off as waste and withthe disposal already constituting a problem in areas where they cannot find any use, the use of this material in the development of an automobile disk brake pad will reduce or eliminate this environmental nuisance.
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Plate1.1Photograph of periwinkle shells
1.1.2 Fan Palm (hyphaenepetersiana)
Fan palm shown in Plate1.2a belongs to the family of (Hyphaene) found in savanna habitats of Africa. It has large gray- green, leaves with stiff segments that are held in a rounded crown atop a massive trunk that can reach 25 m (80 ft.) tall and is usually swollen in the middle. Mature plants carry large round seed see Plate 1.2 andit is highly drought resistant and very adaptable to most weather conditions.Mats, hats and baskets are made from the leaves, the hard white kernel of the seed, termed vegetable ivory, are carved into small ornaments and buttons.
(a) Fan palm Tree (b) Fan Palm Fruit
Plate 1.2Photograph ofFan palm tree and fan palm fruit
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1.2 STATEMENT OF THE PROBLEM
The problem identified by this research is health risk associatedwith the use of asbestos as a friction material and theincompatibility of thenumerous materials currently used in the development of an asbestos free brake pads. Some of these health risksinclude; Asbestosis, Lung cancer, Mesothelioma (a cancer of the linings around the lungs and abdomen), non-cancerous diseases that affect the linings around the lungs and abdomen (commonly called ‘benign pleural diseaseas identified by Dagwa and Ibhadode, (2005).Although several alternative materialssuch as; mineral fibers, cellulose, aramid, poly-acrylo-nitrile (PAN), chopped glass, steel and copper fibers have been used to developed asbestos free brake pads,however, the incompatibility the numerous used in the replacement of asbestos brakes is also a challenge.
Consequent upon the health risk associated with the used of asbestos and the incompatibility of thenumerous ingredients used in the replacement of asbestos as a friction material, the need to develop an asbestosfree brake pad with only 2 ingredients and still maintaining the recommended physical, thermal and mechanicalproperties of a brake pad still remains a challenge to the engineer which the works sought to address.
1.3 THE PRESENT RESEARCH
The present research has been able to overcome the health risk associated with use of asbestos in the development of friction material by using only two (2) materials to develop an eco-friendly brake pad and still achieve the recommended (0.3 to o.35) range of coefficient of friction.
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1.4 AIM AND OBJECTIVES OF THE STUDY
The aim of this research is to widen the scope of locally sourced eco-friendly materials that may be used for production of asbestos – free brake pads.
The specific objectives of this study are:
i. To determine physical thermal and chemical properties of periwinkle and fan palmshells using characterization techniques such as thermo gravimetric analysis (TGA), Scanning electron microscope (SEM), X-ray diffractograms (XRD) and X-Ray Fluorescence (XRF).
ii. To determinetheoptimum periwinkle or fan palm particle size for the formulation of brake pad
iii. To employ Taguchi method to optimize the friction material formulation and the manufacturing parameters.
iv. To determine the physical, mechanical; (hardness, compressive stress friction and wear), chemical and thermal properties of the formulated brake pads.
v. To carry out laboratory and vehicle performance test for the developed brake pad and compare the results with those of a commercial brake pad for the Mercedes Benz 230E salon car
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1.5 SCOPE OF THE STUDY
Experiments were conducted under laboratory conditions to determine the mechanicalproperties (coefficient of friction, wear,compressive strength, hardness strength, oil and water/absorption), thermal properties (thermo gravimetric analysis), the elemental composition of the base materials by using and characterization of the developed brake padsby using Scanning electron microscope (SEM), X-ray diffractograms (XRD) and X-Ray Fluorescence (XRF) of the.The laboratory and vehicle performance test for the developed brake pads were carried out and the resultswere compared favorably withthose in the literature and of the commercial brake pad for the Mercedes Benz 230E salon car.
1. 6 SIGNIFICANCE OF THE STUDY
The significance of the study is enormous but most importantly it is:
I. To encourage the development of small scale industries in Nigeria. Small scale industries play a vital role in the socio- economic development of any country. They strengthen the economy of a nation by utilizing its productive resources with minimum capital investment. The main objective of such a process lies in the absorption of the surplus amount of labour which would not have been absorbed by capital intensive industries. This in turn, helps in scaling down the level of unemployment as well as poverty.
II. To increase Nigerian local content, in the automobile industry: local content means the development of skills, technology transfer, use of manpower and local manufacturing techniques. All the present day industrialized nations are what they are because they have been able to develop skills, apply technology transfer, and use local man power and local manufacturingtechniques and materials Thus the
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production of brake pads material from locally sourced raw materials will encourage local content development in Nigeria.
III. To produce cheaper brake pads: With locally sourced raw materials it is expected that both the cost of materials and production will be low resulting tocheaper brake pads.
IV. Economic and Weight Reduction: Periwinkle shells and Fan palm shells can be obtained at a lower cost compared to the present materials used in the manufacture of brake pads. In addition, their low density of 1.12 (g/cm3) and 0.99 (g/cm3) has the potential of reducing the weight of the brake pad which will lead to the reduction of vehicle weight. This in turn will reduce fuel consumption resulting in less carbon dioxide emission, lower greenhouse effect and reduction in global warming.
V. Health Risk: It is known that asbestos is carcinogenic. However available literature and results obtained from the XRD tests show that both periwinkle shells and fan palm shells do not contain any harmful substances Amarenet al.,(2013).
VI. Added Value: The use of the aforementioned materials in the production of brake pads will encourage the breeding of periwinkles for food, meat and their shells, which have been an environmental nuisance, will be of value.
VII. Renewable Resources: Periwinkles and fan palms shells are renewable and have high potential availability.
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