TABLE OF CONTENTS CHAPTER TITLE PAGE ACKNOWLEDGEMENTS LIST OF SYMBOLS / ABBREVIATIONS

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1 vii TABLE OF CONTENTS CHAPTER TITLE PAGE DECLARATION DEDICATION ACKNOWLEDGEMENTS ABSTRACT ABSTRAK TABLE OF CONTENTS LIST OF TABLES LIST OF FIGURES LIST OF SYMBOLS / ABBREVIATIONS LIST OF APPENDICES ii iii iv v vi vii xii xiv xviii xxi

2 viii 1 INTRODUCTION Background of the Study Problem Statement Objective of the Study Scope of the Study Structure of the Thesis 6 2 LITERATURE REVIEW Introduction Shape Memory Alloys (SMAs) Nickel Titanium Shape Memory Alloys (NiTi 9 SMAs) General Principles Thermomechanical Behavior Properties of NiTi SMA Applications of NiTi SMAs Coating Techniques Physical Vapor Deposition (PVD) 18 Technique Introduction of PVD Technique Magnetron Sputtering Technique Post-sputtering Annealing Process 22

3 ix 2.7 Effect of Post-sputtering Annealing Process on 23 Structure and Tribological Properties of NiTi SMA Coating 2.8 Stainless Steel Material Type of Stainless Steel Stainless Steel 316L Properties of Stainless Steel 316L Composition of Stainless Steel 316L Characterization Methods of NiTi SMA Coating Thermal Properties Structural, Surface and Composition 40 Analysis Mechanical and Tribological Properties 49 3 RESEARCH METHODOLOGY Introduction Flow Chart of Research Activities Substrate Materials Preparation of Stainless Steel 316L 57 Substrate 3.4 Sputtering Physical Vapor Deposition (PVD) 59 Technique

4 x Sputtering Process Parameters Post-sputtering Annealing Process Coating Characterisation Techniques Cross-sectioned Sample Preparation Thermal Analysis Using the Differential 63 Scanning Calorimetry (DSC) Structural, Surface and Composition 64 Analysis Mechanical and Tribological Properties 67 4 RESULTS AND DISCUSSION Introduction Substrate Material Characterization Composition Analysis of 316L Stainless 72 Steel Substrate Composition Analysis of Silicon Substrate Composition Analysis of Unannealed NiTi 75 Coating 4.4 Cross-sectioned of Unannealed NiTi SMA 76 Coating Sample 4.5 Thermal Properties Phase and Crystallographic Plane 80

5 xi Unannealed NiTi SMA Coating Annealed NiTi SMA Coating Surface Morphology and Roughness 85 Measurement Surface Roughness Tester Atomic Force Microscope (AFM) Mechanical and Tribological Properties Rockwell C Adhesion Test Pin-on-disc Wear Test Nanoindentation CONCLUSION AND RECOMMENDATIONS FOR FUTURE WORK Conclusion Recommendations 107

6 xii LIST OF TABLES TABLE NO TITLE PAGE 2.1 NiTi mechanical properties Mechanical properties of 316L stainless steels Physical properties of 316L stainless steel Composition of 316 and 316L stainless steel Rockwell hardness scales Parameters used for grinding process Parameters of post-sputtering annealing process Parameters of grazing angle X-ray diffraction (GAXRD) Parameters of surface roughness tester Parameters of atomic force microscope (AFM) Parameters of Rockwell C adhesion test Parameters of pin-on-disc wear test Parameters of nanoindentation Chemical composition of 316L stainless steel substrate 73

7 xiii 4.2 Chemical composition of unannealed NiTi coated on silicon substrate 4.3 The surface roughness Ra and Ra (average) of NiTi SMA coated on the 316L stainless steel at different parameters 4.4 The Ra and Rms values for the unannealed and annealed 600 C for 30 minutes NiTi SMA coating samples at 1.0 x 1.0 µm² scan area 4.5 The results obtained from the nanoindentation test on the unannealed and annealed 600 C for 30 minutes NiTi SMA coating

8 xiv LIST OF FIGURES FIGURE NO TITLE PAGE 1.1 Structure of the thesis Martensitic transformation and hysteresis (= H) upon a change of temperature. A s = austenite start, A f = austenite finish, M s = martensite start, M f = martensite finish and M d = highest temperature to strain-induced martensite. Gray area = area of optimal superelasticity 2.2 Typical stress-strain curves at different temperatures relative to the transformation showing (a) Austenite, (b) Martensite, (c) Pseudoelastic behavior 2.3 Transformation from the austenite to the martensite phase and shape memory effect 2.4 The procedures are very similar: (a) starting from martensite, (b) adding a reversible deformation for the one-way effect or severe deformation with an irreversible amount for the two-way, (c) heating the sample and (d) cooling it again 2.5 Schematic presentation of lattice structure changes caused by outer stress in stainless steel or superelastic NiTi alloy

9 xv 2.6 Principle of sputter deposition process The different grades of damages to classify the indentation patterns in the Rockwell adhesion test, after Typical DSC curve Schematic diagram of the SEM Some electrons and X-rays ejected from the sample by the incident beam 2.11 Fourteen (14) Bravais lattice patterns, 3-dimensional (3D) Working principle of XRD Surface characteristic A schematic diagram of atomic force microscope (AFM) Working principle of Rockwell hadrness testing Schematic diagram of Pin-on-disc tester Schematic diagram of nanoindenter Load-displacement curve for an instrumented nanoindentation test Flow chart of research activities Mechanism of sputtering process EDX spectra of 316L stainless steel substrate EDX spectra of silicon substrate 74

10 xvi 4.3 EDX spectra of unannealed NiTi coated on silicon substrate 4.4 The measurement of the unannealed NiTi SMA coating thickness by doing a cross-section process on 316L stainless steel. (a) coating layer, (b) interlayer and (c) substrate material 4.5 EDX spectra of (a) coating layer, (b) interlayer and (c) substrate material DSC curve of unannealed NiTi SMA coating XRD pattern of unannealed NiTi SMA coating XRD pattern of the annealed NiTi SMA coatings at temperature 550 C for duration of (a) 30 and (b) 60 minutes 4.9 XRD pattern of the annealed NiTi SMA coatings at temperature 600 C for duration of (a) 30 and (b) 60 minutes 4.10 The AFM typical two-dimensional (2D) surface morphology of the (a) unannealed and (b) annealed at 600 C for 30 minutes samples 4.11 The AFM typical three-dimensional (3D) surface morphology of the (a) unannealed and (b) annealed at 600 C for 30 minutes samples 4.12 The surface morpology of Rockwell C adhesion test with different parameters, (a) unannealed, (b) annealed at 550 C for 30 minutes, (c) annealed at 550 C for 60 minutes, (d) annealed at 600 C for 30 minutes and (e) annealed at 600 C for 60 minutes under the optical observation

11 xvii 4.13 The surface morpology of Rockwell C adhesion test at high magnification image using SEM at different parameters; (a) unannealed, (b) annealed at 550 C for 30 minutes, (c) annealed at 550 C for 60 minutes, (d) annealed at 600 C for 30 minutes and (e) annealed at 600 C for 60 minutes 4.14 Wear tracks morpologies for (a) unannealed, (b) 550 C for 60 minutes and (c) 600 C for 30 minutes under the optical observation 4.15 The wear width measurement and chemical composition analysis of unannealed (a, b) and annealed ((c, d) 550 C (60 min) and (e, f) 600 C (30 min)) by SEM 4.16 The pin-on-disc results for different type of samples; unannealed, 550 C (60 min) and 600 C (30 min) 4.17 Mechanical proeprties versus indentaion depth (a) H versus penetration depth (b) E versus penetration depth and (c) H/E Ratio versus penetration depth

12 xviii LIST OF SYMBOLS/ABBREVIATIONS A f - Austenite Finish Temperature AFM - Atomic Force Micriscope Amrec - Advance Materials Research Centre Ar - Argon A s - Austenite Start Temperature ASTM - American Society for Testing and Materials BCC - Body Centered Cubic BSE - Backscattered Electrons Cr - Chromium CVD - Chemical Vapour Deposition d - Diameter DC - Direct Current DSC - Differential Scanning Calorimetry E - Young s Modulus EDX/EDAX - Energy Dispersive X-ray Spectroscopy FCC - Face Centered Cubic Fe - Iron

13 xix GDS - Glow Discharge Spectroscopy GAXRD - Grazing Incidence Angle X-ray Diffraction GPa - Giga-Pascal H - Hardness H/E - Ratio of Hardness to Young s Modulus IBAD - Ion-Beam Assisted Deposition mbar - Milibar M d - Highest Temperature To Strain-Induced Martensite M f - Martensite Finish Temperature MEMS - Micro-Electro-Mechanical System MPa - Mega-Pascal M s - Martensite Start Temperature Ni - Nickel NiTi - Nickel Titanium OM - Optical Microscopy PDF - Powder Diffraction File PECVD - Plasma Enhanced Chemical Vapour Deposition PVD - Physical Vapour Deposition Ra - Average Roughness RF - Radio Frequency RMS - Root Mean Square Roughness SE - Superelasticity / Secondary Electrons SEM - Scanning Electron Microscopy

14 xx Si - Silicon SiC - Silicon Carbide SMA - Shape Memory Alloy SMAs - Shape Memory Alloys SME - Shape Memory Effect Ti - Titanium TiN - Titanium Nitride TTRs - Transformation Temperatures VDI - Verein Deutscher Ingenieure XRD - X-ray Diffraction 2D - Two-Dimension 3D - Three-Dimension

15 xxi LIST OF APPENDICES APPENDIX TITLE PAGE A Powder diffraction file (PDF) 117 B XRD pattern list 119 C GDS composition analysis (316L stainless steel) 120 D Pin-on-disc measurement 121