Modeling Of Reactively Sputtered TiAIN Coating On Tungsten Carbide Insert Tool : Its Properties And Cutting Performance In Dry Turning Of AISI D2 Steel.
ABSTRACT
An extended theoretical model of reactive sputtering of TiAlN coating has been developed
to study the effect of substrate bias (V b) and nitrogen CN2) flow rate on the coating
composition and deposition rate. The model simulation results showed that the critica l 2
flow rate ({v1) to achieve a stoichiometry composition of unbiased (Vb = 0 V) and biased
(Vb = -80 V) substrate was 4 seem and 3 seem, respectively. At N 2 flow rate lower than
fv/, the coating composition increased with an increase in Vb and N2 flow rate due to the
increase of ion flux to the substrate while the deposition rate decreased due to the coating
densification and the decreased sputtering rate. At N2 flow rate higher than [ N/, the coating
composition and deposition rate ilid not depend on the Vb and N 2 flow rate due to the
dominati on of neutral particles deposition than ions deposition. The model verification
using secondary data showed an accurately prediction on the coating composition and
deposition rate at N 2 fl ow rate higher than [N/. The calculated coating composition at N 2
flow rate lower than f ,-/ showed a devi ation due to heterogeneous reactions between the
sputtered particles (Ti and AJ) and N at the substrate surface, while the deviation of
calcul ated deposition rate was due to coating densification. The experimental investigation
was designed by using Response Surface Methodology (RSM) and conducted by using
magnetron sputtering in deposition of TiAIN coating on WC inserts. The coating
composition and thi ckness were obtained by using SEMIEDX. The coating structure and
morphology were obtained by using XRD and AFM, respectively. The coating hardness
and adhesion were obtained by using ultra-micro hardness test and indentation test,
respecti,·ely. The cutting test was carried out in CNC dry turning of A ISI D2 steel. The
flank \\"ear and surface roughness were obtained by using optical microscopy and surface
roughness tester, respecti,·ely. The results showed that generally the coating composition
of biased substrate (- I 00, -150, -200 V) was consistently higher than that of unbiased
substrate whereas the deposition rate o r biased substrate is lower than that of unbiased
substrate. Analysis of the coating thickness showed that generally the coating thickness
decreased with an increas , in the V b and . 12 flow rate. At N 2 flow rate lower than 50 seem,
the thin nest coating(- 1000 nm) is achieved by unbiased substrate due to low ions fluxes
for reaction at the substrate surface. The coating hardness, structure and morphology were
significantl y influenced by the V b while' the interaction of the Vb and N2 flow rate
significant ly influenced the coating adh-:sion. The coating hardness increased (- 7 GPa)
with an increase in the V b up to -200 V due to decreased coating crystal size. At N 2 flow
rate o f 70 seem, the adhesion strength i Ｑｾ ｲ ･ ｡ｳ ､＠
with an increase in the Vb up to -200 V
due to decreased compressive stress. ·1 he lowest flank wear (- 0.4 mm) due to high
adhesion strength was ach ieved at -200 \' and 70 seem .
11
2.3
2.4
2.5
2.6
2.7
2.8
2.9
3
MODEL OF REACTIVE SPUTTERING
3.1
3.2
3.3
3.4
3.5
3.6
4
TiAIN coating properties
2.3.1 Hardness
2.3.2 Adhesion
2.3.3 Residual stress
2.3.4 Composition
2.3.5 Structure and morphology
2.3.6 Crystal orientation
2.3.7 Coating thickness
Effect of reactive sputtering parameters on TiAIN coating
properties
2.4. 1 Effect of nitrogen flow rate
2.4.2 Effect of nitrogen pressure
2.4.3 Effect of substrate bias
2.4.4 Effect of substrate temperature
2.4.5 Effect of sputtering power
2.4.6 Effect of substrate rotation
2.4.7 Hysteresis effect
Modeling of sputtering process
Experimental design of sputtering process
Cutting tool performance
2.7.1 Tool wear
2.7.2 Tool material
2.7.3 Work material
2.7.4 Surface roughness
Effect of cutting parameters on cutting performance
2.8.1 Effect of cutting parameters on tool wear
2.8.2 Effect of cutting pammeters on surface roughness
Summary
Plasma sheath potential and ion flux
Ion and neutral particles flux in reactive sputtering
ofTiAIN coating
Total particle fluxes in reactive sputtering
3.3 . 1 Reactions at target
3.3.2 Reactions at substrate
Kinetic of the reactive gas
Sputtering and deposition rate
Sensitivity analysis
EXPERIMENTAL INVESTIGATION
4. 1
4.2
Response Surface Methodology
4.1.1 Center Composite Design
4.1 .2 Experimental design and analysis
Experiment procedure
4.2.1 Preliminary experiment ofTiAIN coating depos ition
4.2.2 Experiment ofTiAIN coating deposition
4.2.2.1 Substrate
4.2.2.2 Sputtering parameters
4.2.2.3 Machine of sputtering system
V lll
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103
4.2.2.4 Procedures ofTiAlN coating deposition
4.2.3 Cutting performance test
4.2.3. 1 Tool and work material
4.2.3.2 Cutting condition
Characterization of coating surface and its performance
4.3.1 Optical microscopy
4.3.2 Surface roughness test
4.3.3 Scanning Electron Microscopy (SEM)
and Energy Dispersive X-Ray (EDX)
4.3.4 X-Ray Diffraction (XRD)
4. 3.5 Adhesion test
4.3.6 Ultra-micro hardness test
4.3.7 Atomic Force Microscopy (AFM)
104
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105
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108
109
109
RESULTS AND DISCUSSIONS
5.1
Model simulation results
5.1 .1 Effect of substrate bias at various nitrogen flow rate
5.1.2 Effect of pump speed and target current
5. 1.3 Sensitivity analysis on reactive sputtering model
5. 1.4 Comparison with secondary data
5.1.5 Discussion
5.2
Preliminary experiment of sputtering deposition
5.3
Experimental result of sputtered TiAIN coating:
5.3.I Composition ofTiAIN coating
5.3. I .1 Analysis ofTiAIN coating composition
5.3.1.2 Analysis ofTiAIN coating composition
using RSM
A. Analysis ofTi/Al ratio
B. Analysis of Ti/(Ti+Al+N) ratio
5.3 .1.3 Discussion
5.3.2 Deposition rate
5.3.2.1 Effect of substrate bias on TiAIN coating
thickness
5.3.2.2 Effect of nitrogen flow rate on TiAIN coating
thickness
5.3.2.3 Discussion
5.3.3 Structure ofTiAIN coating
5.3.3.1 Substrate (tungsten carbide insert)
5.3.3.2 Effect of substrate bias on TiAIN coating
structure
5.3.3.3 Effect of nitrogen flow rate on TiAIN coating
Structure
5.3.3.4 Analysis ofTiAIN coating structure using RSM
A. Analysis of crystal plane spacing of ( 111 )
TiAlN coating
B. Analysis of crystal size of (Il l )
TiAlN coating
5.3 .3 .5 Disc ussion
115
11 6
118
120
122
129
139
145
147
I47
153
4.3
5
IX
110
Ill
113
I I3
114
157
"158
162
166
168.
173
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182
185
185
186
193
200
20 I
205
21 0
5.3 .4
5.4
5.5
5.6
Morphology of TiAlN coating
5.3 .4.1 Effect of substrate bias on TiAIN coating
roughness
5.3.4.2 Effect of nitrogen fl ow rate on TiAlN coating
roughness
5.3.4.3 Analysis ofTiAlN coating roughness
using RSM
5.3.4.4 Discussion
5.3.5 Hardness of TiAIN coating
5.3.5. 1 Effect of substrate bias on TiAIN coating
hardness
5.3.5.2 Effect of nitrogen flow rate on TiAIN coating
hardness
5.3.5.3 Analysis ofTiAIN coating hardness
usingRSM
5.3.5.4 Discussion
5.3.6 Adhesion of TiAlN coating
5.3 .6.1 Effect of substrate bias on TiAIN coating
adhesion
5.3.6.2 Effect of nitrogen flo w rate on TiAlN coating
adhesion
5.3.6.3 Analysis ofTiAlN coating adhesion using RSM
5.3.6.4 Discussion
Study of cutting parameters optimization using RSM
5.4. 1 Analysis of cutting parameters effect on flank wear
5.4.2 Analysis of cutting parameters effect
on surface roughness
5.4.3 Optimization of flar..k wear and surface roughness
5.4.4 Discussion
Cutting performance ofTiAIN coating
5.5. 1 Analysis of sputtering parameters effect on
TiAlN coating flank wear
5.5. 1. 1 Effect of substrate bias on
TiAIN coating flank wear
5.5. 1.2 Effect of nitrogen flow rate on
TiAIN coating flank wear
5.5.2 Analysis ofTiAlN coating fl ank wear
usingRSM
5.5.3 Analysis of surface roughness using RSM
5.5.4 Comparison ofTiAl coating performance
5.5.5 Discussion
Summary of the results
5.6. 1 Correlation of TiAlN coating properties
and its cutting perfonnance
5.6.2 Correlation of TiAIN coating properties
X
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28 1
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296
S.83
Optimum cond ition to achieve lowest surface roughness
271
5.84
Optimum condition to achieve lowest flank wear
and surface roughness
273
Optical microscopy of TiAlN coating flank wear at
various substrate bias and nitrogen flow rate of:
(a) 70 seem ; (b) 6S seem; (c) 60 seem. Magnification is SOx
277
TiAIN coating flank wear at various nitrogen fl ow rate
and substrate bias
278
Optical microscopy ofTiAIN coating flank wear
at various nitrogen flow rate and substrate bias of:
(a) -100 V; (b) -ISO V; (c) -200 V. Magnification is SOx
279
S.88
TiAlN coating flank wear at various nitrogen flow rate
280
S.89
TiAIN coating flank wear at: (a) N 2 flow of 6S seem
and various substrate bias; (b) substrate bias of - 1SO V
and various nitrogen flow rate
283
Three dimension graph ofTiAlN coating flank wear
as function of substrate bias and nitrogen flow rate
284
Three dimension graph of surface roughness
as function of substrate bias and nitrogen flow rate
286
S.92
Correlation of flank wear and hardness of TiAIN coating
290
S.93
Correlation of flank wear and adhesion strength
of TiAIN coating
29 1
Correlation of flank wear and ( 111 ) crystal plane spacing
of TiAIN coating
291
Correlation of flank wear and rrns roughness
ofTiAlN coating surface
292
Correlation of flank wear and composition ofTiAIN coating:
(a) Ti content; (b) AI content; (c) N content
294
5.97
Correlation of flank wear and thickness ofTiAlN coating
29S
5.98
Correlation of adhesion strength and d 111 of TiAlN coating
296
5.99
Correlation of hardness and adhesion strength of TiAIN coating
297
5. 100
Correlation of hardness and ( Ill ) crystal plane spacing of
T iAlN coating
298
5.10 1
Correlation of hardness and roughness of TiAlN coating
7.99
S.l02
Correlation of hardness and thi ckness of TiAIN coating
300
5. 103
Correlati on of adhes ion strength and thickness of
TiAlN coating
30 1
Correlation of adhesion strength and composition of
TiAIN coating: (a) Ti content; (b) AI content; (c) N content
302
S.8S
5.86
S.87
S.90
S.91
S.9-l
5.95
5.96
5. 104
XX III
An extended theoretical model of reactive sputtering of TiAlN coating has been developed
to study the effect of substrate bias (V b) and nitrogen CN2) flow rate on the coating
composition and deposition rate. The model simulation results showed that the critica l 2
flow rate ({v1) to achieve a stoichiometry composition of unbiased (Vb = 0 V) and biased
(Vb = -80 V) substrate was 4 seem and 3 seem, respectively. At N 2 flow rate lower than
fv/, the coating composition increased with an increase in Vb and N2 flow rate due to the
increase of ion flux to the substrate while the deposition rate decreased due to the coating
densification and the decreased sputtering rate. At N2 flow rate higher than [ N/, the coating
composition and deposition rate ilid not depend on the Vb and N 2 flow rate due to the
dominati on of neutral particles deposition than ions deposition. The model verification
using secondary data showed an accurately prediction on the coating composition and
deposition rate at N 2 fl ow rate higher than [N/. The calculated coating composition at N 2
flow rate lower than f ,-/ showed a devi ation due to heterogeneous reactions between the
sputtered particles (Ti and AJ) and N at the substrate surface, while the deviation of
calcul ated deposition rate was due to coating densification. The experimental investigation
was designed by using Response Surface Methodology (RSM) and conducted by using
magnetron sputtering in deposition of TiAIN coating on WC inserts. The coating
composition and thi ckness were obtained by using SEMIEDX. The coating structure and
morphology were obtained by using XRD and AFM, respectively. The coating hardness
and adhesion were obtained by using ultra-micro hardness test and indentation test,
respecti,·ely. The cutting test was carried out in CNC dry turning of A ISI D2 steel. The
flank \\"ear and surface roughness were obtained by using optical microscopy and surface
roughness tester, respecti,·ely. The results showed that generally the coating composition
of biased substrate (- I 00, -150, -200 V) was consistently higher than that of unbiased
substrate whereas the deposition rate o r biased substrate is lower than that of unbiased
substrate. Analysis of the coating thickness showed that generally the coating thickness
decreased with an increas , in the V b and . 12 flow rate. At N 2 flow rate lower than 50 seem,
the thin nest coating(- 1000 nm) is achieved by unbiased substrate due to low ions fluxes
for reaction at the substrate surface. The coating hardness, structure and morphology were
significantl y influenced by the V b while' the interaction of the Vb and N2 flow rate
significant ly influenced the coating adh-:sion. The coating hardness increased (- 7 GPa)
with an increase in the V b up to -200 V due to decreased coating crystal size. At N 2 flow
rate o f 70 seem, the adhesion strength i Ｑｾ ｲ ･ ｡ｳ ､＠
with an increase in the Vb up to -200 V
due to decreased compressive stress. ·1 he lowest flank wear (- 0.4 mm) due to high
adhesion strength was ach ieved at -200 \' and 70 seem .
11
2.3
2.4
2.5
2.6
2.7
2.8
2.9
3
MODEL OF REACTIVE SPUTTERING
3.1
3.2
3.3
3.4
3.5
3.6
4
TiAIN coating properties
2.3.1 Hardness
2.3.2 Adhesion
2.3.3 Residual stress
2.3.4 Composition
2.3.5 Structure and morphology
2.3.6 Crystal orientation
2.3.7 Coating thickness
Effect of reactive sputtering parameters on TiAIN coating
properties
2.4. 1 Effect of nitrogen flow rate
2.4.2 Effect of nitrogen pressure
2.4.3 Effect of substrate bias
2.4.4 Effect of substrate temperature
2.4.5 Effect of sputtering power
2.4.6 Effect of substrate rotation
2.4.7 Hysteresis effect
Modeling of sputtering process
Experimental design of sputtering process
Cutting tool performance
2.7.1 Tool wear
2.7.2 Tool material
2.7.3 Work material
2.7.4 Surface roughness
Effect of cutting parameters on cutting performance
2.8.1 Effect of cutting parameters on tool wear
2.8.2 Effect of cutting pammeters on surface roughness
Summary
Plasma sheath potential and ion flux
Ion and neutral particles flux in reactive sputtering
ofTiAIN coating
Total particle fluxes in reactive sputtering
3.3 . 1 Reactions at target
3.3.2 Reactions at substrate
Kinetic of the reactive gas
Sputtering and deposition rate
Sensitivity analysis
EXPERIMENTAL INVESTIGATION
4. 1
4.2
Response Surface Methodology
4.1.1 Center Composite Design
4.1 .2 Experimental design and analysis
Experiment procedure
4.2.1 Preliminary experiment ofTiAIN coating depos ition
4.2.2 Experiment ofTiAIN coating deposition
4.2.2.1 Substrate
4.2.2.2 Sputtering parameters
4.2.2.3 Machine of sputtering system
V lll
24
24
29
31
33
33
37
41
42
42
43
45
48
49
50
51
52
56
57
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81
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94
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102
102
103
4.2.2.4 Procedures ofTiAlN coating deposition
4.2.3 Cutting performance test
4.2.3. 1 Tool and work material
4.2.3.2 Cutting condition
Characterization of coating surface and its performance
4.3.1 Optical microscopy
4.3.2 Surface roughness test
4.3.3 Scanning Electron Microscopy (SEM)
and Energy Dispersive X-Ray (EDX)
4.3.4 X-Ray Diffraction (XRD)
4. 3.5 Adhesion test
4.3.6 Ultra-micro hardness test
4.3.7 Atomic Force Microscopy (AFM)
104
105
105
108
108
109
109
RESULTS AND DISCUSSIONS
5.1
Model simulation results
5.1 .1 Effect of substrate bias at various nitrogen flow rate
5.1.2 Effect of pump speed and target current
5. 1.3 Sensitivity analysis on reactive sputtering model
5. 1.4 Comparison with secondary data
5.1.5 Discussion
5.2
Preliminary experiment of sputtering deposition
5.3
Experimental result of sputtered TiAIN coating:
5.3.I Composition ofTiAIN coating
5.3. I .1 Analysis ofTiAIN coating composition
5.3.1.2 Analysis ofTiAIN coating composition
using RSM
A. Analysis ofTi/Al ratio
B. Analysis of Ti/(Ti+Al+N) ratio
5.3 .1.3 Discussion
5.3.2 Deposition rate
5.3.2.1 Effect of substrate bias on TiAIN coating
thickness
5.3.2.2 Effect of nitrogen flow rate on TiAIN coating
thickness
5.3.2.3 Discussion
5.3.3 Structure ofTiAIN coating
5.3.3.1 Substrate (tungsten carbide insert)
5.3.3.2 Effect of substrate bias on TiAIN coating
structure
5.3.3.3 Effect of nitrogen flow rate on TiAIN coating
Structure
5.3.3.4 Analysis ofTiAIN coating structure using RSM
A. Analysis of crystal plane spacing of ( 111 )
TiAlN coating
B. Analysis of crystal size of (Il l )
TiAlN coating
5.3 .3 .5 Disc ussion
115
11 6
118
120
122
129
139
145
147
I47
153
4.3
5
IX
110
Ill
113
I I3
114
157
"158
162
166
168.
173
177
182
185
185
186
193
200
20 I
205
21 0
5.3 .4
5.4
5.5
5.6
Morphology of TiAlN coating
5.3 .4.1 Effect of substrate bias on TiAIN coating
roughness
5.3.4.2 Effect of nitrogen fl ow rate on TiAlN coating
roughness
5.3.4.3 Analysis ofTiAlN coating roughness
using RSM
5.3.4.4 Discussion
5.3.5 Hardness of TiAIN coating
5.3.5. 1 Effect of substrate bias on TiAIN coating
hardness
5.3.5.2 Effect of nitrogen flow rate on TiAIN coating
hardness
5.3.5.3 Analysis ofTiAIN coating hardness
usingRSM
5.3.5.4 Discussion
5.3.6 Adhesion of TiAlN coating
5.3 .6.1 Effect of substrate bias on TiAIN coating
adhesion
5.3.6.2 Effect of nitrogen flo w rate on TiAlN coating
adhesion
5.3.6.3 Analysis ofTiAlN coating adhesion using RSM
5.3.6.4 Discussion
Study of cutting parameters optimization using RSM
5.4. 1 Analysis of cutting parameters effect on flank wear
5.4.2 Analysis of cutting parameters effect
on surface roughness
5.4.3 Optimization of flar..k wear and surface roughness
5.4.4 Discussion
Cutting performance ofTiAIN coating
5.5. 1 Analysis of sputtering parameters effect on
TiAlN coating flank wear
5.5. 1. 1 Effect of substrate bias on
TiAIN coating flank wear
5.5. 1.2 Effect of nitrogen flow rate on
TiAIN coating flank wear
5.5.2 Analysis ofTiAlN coating fl ank wear
usingRSM
5.5.3 Analysis of surface roughness using RSM
5.5.4 Comparison ofTiAl coating performance
5.5.5 Discussion
Summary of the results
5.6. 1 Correlation of TiAlN coating properties
and its cutting perfonnance
5.6.2 Correlation of TiAIN coating properties
X
212
213
217
221
226
229
230
232
235
239
243
244
246
249
255
256
258
265
272
273
275
276
276
278
28 1
284
286
287
289
289
296
S.83
Optimum cond ition to achieve lowest surface roughness
271
5.84
Optimum condition to achieve lowest flank wear
and surface roughness
273
Optical microscopy of TiAlN coating flank wear at
various substrate bias and nitrogen flow rate of:
(a) 70 seem ; (b) 6S seem; (c) 60 seem. Magnification is SOx
277
TiAIN coating flank wear at various nitrogen fl ow rate
and substrate bias
278
Optical microscopy ofTiAIN coating flank wear
at various nitrogen flow rate and substrate bias of:
(a) -100 V; (b) -ISO V; (c) -200 V. Magnification is SOx
279
S.88
TiAlN coating flank wear at various nitrogen flow rate
280
S.89
TiAIN coating flank wear at: (a) N 2 flow of 6S seem
and various substrate bias; (b) substrate bias of - 1SO V
and various nitrogen flow rate
283
Three dimension graph ofTiAlN coating flank wear
as function of substrate bias and nitrogen flow rate
284
Three dimension graph of surface roughness
as function of substrate bias and nitrogen flow rate
286
S.92
Correlation of flank wear and hardness of TiAIN coating
290
S.93
Correlation of flank wear and adhesion strength
of TiAIN coating
29 1
Correlation of flank wear and ( 111 ) crystal plane spacing
of TiAIN coating
291
Correlation of flank wear and rrns roughness
ofTiAlN coating surface
292
Correlation of flank wear and composition ofTiAIN coating:
(a) Ti content; (b) AI content; (c) N content
294
5.97
Correlation of flank wear and thickness ofTiAlN coating
29S
5.98
Correlation of adhesion strength and d 111 of TiAlN coating
296
5.99
Correlation of hardness and adhesion strength of TiAIN coating
297
5. 100
Correlation of hardness and ( Ill ) crystal plane spacing of
T iAlN coating
298
5.10 1
Correlation of hardness and roughness of TiAlN coating
7.99
S.l02
Correlation of hardness and thi ckness of TiAIN coating
300
5. 103
Correlati on of adhes ion strength and thickness of
TiAlN coating
30 1
Correlation of adhesion strength and composition of
TiAIN coating: (a) Ti content; (b) AI content; (c) N content
302
S.8S
5.86
S.87
S.90
S.91
S.9-l
5.95
5.96
5. 104
XX III