vii
TABLE OF CONTENTS
CHAPTER
TITLE
PAGE
DECLARATION
ii
DEDICATION
iii
ACKNOWLEDGEMENTS
iv
ABSTRACT
v
ABSTRAK
vi
TABLE OF CONTENTS
vii
LIST OF TABLES
xii
LIST OF FIGURES
xiv
LIST OF SYMBOLS / ABBREVIATIONS
xviii
LIST OF APPENDICES
xxi
viii
1
2
INTRODUCTION
1
1.1
Background of the Study
1
1.2
Problem Statement
3
1.3
Objective of the Study
4
1.4
Scope of the Study
5
1.5
Structure of the Thesis
6
LITERATURE REVIEW
7
2.1
Introduction
7
2.2
Shape Memory Alloys (SMAs)
8
2.3
Nickel Titanium Shape Memory Alloys (NiTi
9
SMAs)
2.3.1 General Principles
9
2.3.2 Thermomechanical Behavior
10
2.3.3 Properties of NiTi SMA
12
2.4
Applications of NiTi SMAs
17
2.5
Coating Techniques
17
2.5.1 Physical Vapor Deposition (PVD)
18
Technique
2.6
2.5.1.1 Introduction of PVD Technique
18
2.5.1.2 Magnetron Sputtering Technique
19
Post-sputtering Annealing Process
22
ix
2.7
Effect of Post-sputtering Annealing Process on
23
Structure and Tribological Properties of NiTi
SMA Coating
2.8
2.9
2.10
Stainless Steel Material
28
2.8.1 Type of Stainless Steel
28
Stainless Steel 316L
30
2.9.1 Properties of Stainless Steel 316L
31
2.9.2 Composition of Stainless Steel 316L
35
Characterization Methods of NiTi SMA Coating
37
2.10.1 Thermal Properties
38
2.10.2 Structural, Surface and Composition
40
Analysis
2.10.3 Mechanical and Tribological Properties
3
49
RESEARCH METHODOLOGY
55
3.1
Introduction
55
3.2
Flow Chart of Research Activities
56
3.3
Substrate Materials
57
3.3.1 Preparation of Stainless Steel 316L
57
Substrate
3.4
Sputtering Physical Vapor Deposition (PVD)
Technique
59
x
3.4.1 Sputtering Process Parameters
60
3.5
Post-sputtering Annealing Process
61
3.6
Coating Characterisation Techniques
62
3.6.1 Cross-sectioned Sample Preparation
62
3.6.2 Thermal Analysis Using the Differential
63
Scanning Calorimetry (DSC)
3.6.3 Structural, Surface and Composition
64
Analysis
3.6.4 Mechanical and Tribological Properties
4
67
RESULTS AND DISCUSSION
71
4.1
Introduction
71
4.2
Substrate Material Characterization
72
4.2.1 Composition Analysis of 316L Stainless
72
Steel Substrate
4.3
4.2.2 Composition Analysis of Silicon Substrate
74
Composition Analysis of Unannealed NiTi
75
Coating
4.4
Cross-sectioned of Unannealed NiTi SMA
76
Coating Sample
4.5
Thermal Properties
79
4.6
Phase and Crystallographic Plane
80
xi
4.7
4.6.1 Unannealed NiTi SMA Coating
80
4.6.2 Annealed NiTi SMA Coating
82
Surface Morphology and Roughness
85
Measurement
4.8
5
4.7.1 Surface Roughness Tester
85
4.7.2 Atomic Force Microscope (AFM)
86
Mechanical and Tribological Properties
91
4.8.1 Rockwell C Adhesion Test
91
4.8.2 Pin-on-disc Wear Test
95
4.8.3 Nanoindentation
102
CONCLUSION AND RECOMMENDATIONS FOR
106
FUTURE WORK
5.1
Conclusion
106
5.2
Recommendations
107
xii
LIST OF TABLES
TABLE NO
TITLE
PAGE
2.1
NiTi mechanical properties
25
2.2
Mechanical properties of 316L stainless steels
32
2.3
Physical properties of 316L stainless steel
33
2.4
Composition of 316 and 316L stainless steel
36
2.5
Rockwell hardness scales
50
3.1
Parameters used for grinding process
58
3.2
Parameters of post-sputtering annealing process
61
3.3
Parameters of grazing angle X-ray diffraction (GAXRD) 65
3.4
Parameters of surface roughness tester
66
3.5
Parameters of atomic force microscope (AFM)
67
3.6
Parameters of Rockwell C adhesion test
68
3.7
Parameters of pin-on-disc wear test
69
3.8
Parameters of nanoindentation
70
4.1
Chemical composition of 316L stainless steel substrate
73
xiii
4.2
Chemical composition of unannealed NiTi coated on 76
silicon substrate
4.3
The surface roughness Ra and Ra (average) of NiTi 86
SMA coated on the 316L stainless steel at different
parameters
4.4
The Ra and Rms values for the unannealed and annealed 90
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 103
the unannealed and annealed 600°C for 30 minutes NiTi
SMA coating
xiv
LIST OF FIGURES
FIGURE NO
TITLE
PAGE
1.1
Structure of the thesis
6
2.1
Martensitic transformation and hysteresis (= H) upon a
10
change of temperature. As = austenite start, Af =
austenite finish, Ms = martensite start, Mf = martensite
finish and Md = highest temperature to strain-induced
martensite. Gray area = area of optimal superelasticity
2.2
Typical stress-strain curves at different temperatures
11
relative to the transformation showing (a) Austenite,
(b) Martensite, (c) Pseudoelastic behavior
2.3
Transformation from the austenite to the martensite
13
phase and shape memory effect
2.4
The procedures are very similar: (a) starting from
15
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
16
xv
2.6
Principle of sputter deposition process
21
2.7
The different grades of damages to classify the
26
indentation patterns in the Rockwell adhesion test,
after
2.8
Typical DSC curve
39
2.9
Schematic diagram of the SEM
41
2.10
Some electrons and X-rays ejected from the sample by
42
the incident beam
2.11
Fourteen (14) Bravais lattice patterns, 3-dimensional
44
(3D)
2.12
Working principle of XRD
45
2.13
Surface characteristic
46
2.14
A schematic diagram of atomic force microscope
48
(AFM)
2.15
Working principle of Rockwell hadrness testing
51
2.16
Schematic diagram of Pin-on-disc tester
52
2.17
Schematic diagram of nanoindenter
53
2.18
Load-displacement
curve
for
an
instrumented
54
nanoindentation test
3.1
Flow chart of research activities
56
3.2
Mechanism of sputtering process
60
4.1
EDX spectra of 316L stainless steel substrate
72
4.2
EDX spectra of silicon substrate
74
xvi
4.3
EDX spectra of unannealed NiTi coated on silicon
75
substrate
4.4
The measurement of the unannealed NiTi SMA
77
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)
78
substrate material
4.6
DSC curve of unannealed NiTi SMA coating
80
4.7
XRD pattern of unannealed NiTi SMA coating
81
4.8
XRD pattern of the annealed NiTi SMA coatings at
83
temperature 550°C for duration of (a) 30 and (b) 60
minutes
4.9
XRD pattern of the annealed NiTi SMA coatings at
84
temperature 600°C for duration of (a) 30 and (b) 60
minutes
4.10
The AFM typical two-dimensional (2D) surface
88
morphology of the (a) unannealed and (b) annealed at
600°C for 30 minutes samples
4.11
The AFM typical three-dimensional (3D) surface
89
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
92
xvii
4.13
The surface morpology of Rockwell C adhesion test at
94
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
96
for 60 minutes and (c) 600°C for 30 minutes under the
optical observation
4.15
The
wear
width
measurement
and
chemical
98
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;
101
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
104
xviii
LIST OF SYMBOLS/ABBREVIATIONS
Af
-
Austenite Finish Temperature
AFM
-
Atomic Force Micriscope
Amrec
-
Advance Materials Research Centre
Ar
-
Argon
As
-
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
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
Md
-
Highest Temperature To Strain-Induced Martensite
Mf
-
Martensite Finish Temperature
MEMS
-
Micro-Electro-Mechanical System
MPa
-
Mega-Pascal
Ms
-
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
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
xxi
LIST OF APPENDICES
APPENDIX
TITLE
PAGE
A
Powder diffraction file (PDF)
117
B
XRD pattern list
119
C
GDS composition analysis (316L stainless
120
steel)
D
Pin-on-disc measurement
121