Contents

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Page No

Title page i

Certificate of approval ii

Certificate iii

Declaration iv

Acknowledgement v

List of symbols vii

Abstract viii

Contents ix

Chapter 1 Introduction and Literature Survey

1.1 Surface Engineering 1

1.2 Classification of Surface Engineering Processes 2 1.2.1 Modification of surface without altering the

chemical constitution 2

1.2.1.1 By heating 2

1.2.1.2 By mechanical working 2 1.2.2 Modification of surface by altering the chemical

constitution 2

1.2.2.1 Thermochemical diffusion treatments 2 1.2.2.2 Electroplating and thermal diffusion

treatments 3

1.2.2.3 Anodizing treatments 3

1.2.2.4 Parkerizing 3

1.2.3 Application of new material to the surface 3 1.2.3.1 Coatings deposited in solid state 3 1.2.3.2 Coatings deposited in the liquid state 3

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1.2.3.3 Coatings deposited from solution by

reduction of ions 4 1.2.3.4 Coatings deposited from a vapour 4 1.3 Lasers in Surface Engineering 4

1.3.1 Advantages and disadvantages of CO2 and

Diode laser 6

1.3.1.1 CO2 Lasers 6

1.3.1.2 Diode lasers 7

1.3.2 Parameters affecting quality of laser surface

engineering processes 7 1.3.3 Process description for some laser surface

engineering techniques 8 1.3.3.1 Laser heat treatment 8 1.3.3.2 Laser surface hardening 8 1.3.3.3 Surface hardening by laser particle

injection 9

1.3.3.4 Pulsed laser deposition (PLD) 9

1.3.3.5 Laser cladding 9

1.3.3.6 Laser can also be used to initiate SHS (Self-propagating High–temperature

Synthesis) reaction 10 1.3.4 Laser surface alloying (LSA) 10

1.3.4.1 Laser surface alloying with preplaced

powder 11

1.3.5 Laser post treatment or laser glazing 12 1.4 Self-propagating High-temperature Synthesis (SHS) 13 1.5 Composite Materials and its Classification 14

1.5.1 Development of composites by in-situ and ex-

situ Routes 16

1.6 Introduction to Wear and Wear Resistance 17 1.6.1 Classification of wear: generalized approach 17

1.6.1.1 Adhesive wear 18

1.6.1.2 Abrasive wear and asperity

deformation 18 1.6.1.3 Fatigue and delamination wear 19

1.6.1.4 Chemical wear 19

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1.6.2 Classification of wear: Velocity

accommodation approach 20 1.6.3 Time dependent behaviour of wear 22

1.6.4 Solid lubrication 23

1.6.5 Mechanical and tribological performance of

some single phase composites 26

1.6.5.1 Al2O3 26

1.6.5.2 TiB2 28

1.6.5.3 TiN 28

1.6.6 Ti-B-N based coating 29 1.6.7 Mechanical and tribological behaviour of multi-

phase composite coatings 31 1.6.8 Effects of laser post-treatment on composite

coatings 35

1.7 Nanostructured Coating 37

1.8 Problem Definition 41

1.9 Objectives of the investigation 42

1.10 Work Plan 43

Chapter 2 Experimental Methods and Conditions 45 2.1 Precursor Powders for Development of Coating 45 2.2 Preparation of Substrate Samples for LSA 46 2.3 Details of Laser Machine set-ups Used for the

Investigation 47

2.4 Details of Substrate Materials 48 2.5 Characterisations of the Coatings 49

2.5.1 Physical characterisation 49 2.5.1.1 Scanning Electron Microscopy

(SEM) 49

2.5.1.2 High Resolution Transmission

Electron Microscopy (HRTEM) 50

2.5.1.3 X-ray diffraction (XRD) 50 2.5.1.4 X-ray photoelectron spectroscopy

(XPS) 51

2.5.2 Mechanical characterisation 52 2.5.2.1 Vickers microhardness test 52

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2.5.2.2 Pin-on-disc test 52 Chapter 3 Development of Nanostructured Al₂O₃-TiB₂-TiN Coatings by

Combined SHS and Laser Surface Alloying

3.1 Introduction 55

3.2 Experimental Details 56

3.3 Results and Discussion 57

3.4 Conclusions 65

Chapter 4 Performance Evaluation of Al₂O₃-TiB₂-TiN Composite Coatings with in-situ and ex-situ Reinforcements

4.1 Introduction 67

4.2 Experimental Details 67

4.3 Results and Discussion 69

4.4 Conclusions 78

Chapter 5 Effect of hBN Addition on the Properties of Nanostructured Al2O3-TiB2-TiN Based Coatings

5.1 Introduction 79

5.2 Experimental Details 80

5.3 Results and Discussion 82

5.4 Conclusions 93

Chapter 6 Study on the Effect of Laser Post-treatment on the Properties of Nanostructured Al2O3-TiB2-TiN Based Coatings

6.1 Introduction 95

6.2 Experimental Details 95

6.3 Results and Discussion 96

6.4 Conclusions 108

Chapter 7 Effect of Laser Post-treatment on Al2O3-TiB2-TiN Composite Coating with Free hBN

7.1 Introduction 109

7.2 Experimental Details 109

7.3 Results and Discussion 110

7.4 Conclusions 115

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Chapter 8 Overall Conclusions and Major Contributions

8.1 Summary of Thesis 117 8.1.1 Effect of SHS (comparison between in-situ and

ex-situ techniques of production of coating) 117 8.1.2 Effect of hBN 118 8.1.3 Effect of Laser Post-treatment 119 8.1.4 Combined Effect of Laser Post-treatment and

hBN Content 121

8.2 Overall Conclusions 121

8.3 Major Contributions 122

8.4 Future Scope of Work 122

References 125

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