Nghiên cứu chế tạo và đặc trưng tính chất của màng phủ nitrua trên nền hợp kim cứng WC co bằng phương pháp phún xạ magnetron tt tiếng anh

MINISTRY OF EDUCATION

VIETNAM ACADEMY OF

AND TRAINING

SCIENCE AND TECHNOLOGY

GRADUEATE UNIVERSITY SCIENCE AND TECHNOLOGY
----------------------------------LUONG VAN DUONG

FABRICATION AND CHARACTERIZATION OF NITRIDE
COATINGS ON WC-Co HARD ALLOY BY MAGNETRON
SPUTTERING

Major: Metal Science
Code: 9.44.01.29

SUMMARY OF MATERIASLS SCIENCE
DOCTORAL THESIS

HANOI – 2019


PREFACE
1. Urgency of the thesis
The abrasion and corrosion are the cause of energy loss and
material loss, which reduced performace and lifetime of cutting tools
and machine parts in industry. In industrialized countries some 30 %
of all energy generated is ultimately lost through friction. In the
highly industrialized countries losses due to friction and wear are put

at between 1 and 2 % of gross national product. Therefore, research
on fabrication and devolope the coatings with excellent properties
such as high hardness, low friction coeficience, high corrosion
resistance, and thermal stability are in great demand in moderm
industry [1].
Over the past several decades, the coatings with different
features, from single-layer films with single element such as TiN [23], TiC [4-6], CrN [7 -9] to single-layer films with multi-element
such as TiAlN [10-11], TiAlSiN [12], TiAlBN have been studied. In
addition, the fabrication of TiN/CrN and TiAlN/CrN multilayer films
to combine the good characteristics of each monolayer is also studied
and developed simultaneously [14-15]. For fabrication of the
coatings, some methods such as physical vapor deposition (PVD),
chemical vapor deposition (CVD), and physical chemistry have been
used. However, the PVD method is commonly used because it has
high performance, good adhesion, high density and can deposite on
large tools and parts.
In Vietnam, the study on fabrication of nitride coatings have
been attracted the attention of many research groups in both
fabrication technology and applications at Universities and Institutes
such as: Hanoi university of Science and Technology, University of
1


Science, Vietnam National University Ho Chi Minh City, The

National Research Institute of Mechanical Engineering ...etc.
The single-layer films TiN, Cr [16-17] and muti-layer films
TiN/TiCN [18], TiN/CrN [19] are focused on studing. It can be seen
that the most of studies only focused on single-element nitride films
(commercial targets), which have not been fabricated multi-element

nitride films yet because a target with multi-component is not still
fabricated yet. Therefore, the application of these studies is very
limited.
From 2013 up to now, Institute of Materials Science in
conjunction with Korea Institute of Industrial Technology has
performed the join projects of nitride coatings with multicomponents on WC-Co hard alloys. Moreover, the targets of multicomponents are also fabricated.
As mention above, it is a desire to form the nitride hard
coatings with high hardness and low friction coefficient and expand
the applicability of these coatings in industries. In my thesis, the title
is selected as: "Study on fabrication and properties of nitride coatings
on WC-Co hard alloys by magnetron sputtering".
2. Scope of thesis
- Fabrication and characteristics of single-layer nitride hard coating
with multi-components (TiAlXN (X: Si, B, V)) and multi-layer
nitride hard coating with multi-components TiAlXN/CrN (X: Si, B)
with high hardness and low friction coefficient.
- To determine the influence of main parameters on the properties
of coatings.
3. Main contents of thesis

2


- Introduction of single-layer and multi-layer nitride coatings
in Vietnam and the world.
- Introduction of fabricated method of coatings and
devolopment mechanism of coatings.
- Research on fabrication of single-layer nitride coatings
TiAlXN (X: Si, B, V) by magnetron sputtering, consist of:
+ Research on effect of basis parameters as power, pressure,

distance of target and substrate on hardness of the coatings.
+ Research on effect of nitrogen gas flow rate on the
properties of single-layer nitride coatings.
- Research on fabrication of multi-layer nitride coatings by
magnetron sputtering and characteristics of the coatings.
Main results of thesis
- Single-layer nitride hard coating with multi-components (TiAlXN
(X: Si, B, V)) and multi-layer nitride hard coating with multicomponents TiAlXN/CrN (X: Si, B) have been fabricated
successfully by magnetron sputtering on the WC-Co hard alloys.
- With regard to single-layer hard coatings, research on effect of N2
gas low rate on the properties of 03 coatings (TiAlXN) using by
Ti50Al40X10 (X: Si, B, V) target. Namely, the optimal N2 gas flow rate
is determined at 6 sccm for TiAlSiN and TiAlVN coating, at 4 sccm
for TiAlBN coating.
- With regard to multi-layer hard coating of TiAlSiN/CrN and
TiAlBN/CrN, research on effect of bi-layer thickness and the pairs
number of coatings on the hardness of multi-layer coatings. Namely,
TiAlSiN/CrN coating has highest hardness at bi-layer thickness of
245 nm (thickness of TiAlSiN is 127 nm and thickness of CrN is 118
nm) and pairs total of coating is 6 (12 layers). With regard to
3


TiAlBN/CrN coating, the highest hardness is obtained at the bi-layer
thickness of 232 nm and pairs total of coating is 7 (14 layers).
CHAPTER 1. INTRODUCTION
- Introduction of concepts and devolopment history of coating
- Introduction of single-layer nitride coatings and multi-layer
nitride coating in the world.
- Introduction of structure of TiN, AlN, TiAlN, CrN.

- Introduction of fabricated methods, including: chemiscal vapor
deposition (CVD), physical vapor deposition (PVD). In this thesis,
the PVD method is used for deposited single layer coatings and multi
layer coatings. This is also a common method to be used in the
manufacturing industry because it is a simple, easy-to-control, and
automated method.
- Formation process of coating by sputtering method and
applications of nitride coating as well as research situation in
Vietnam.
CHƯƠNG 2. EXPERIMENTAL AND RESEARCH
APPROCHES
2.1. Fabrication of nitride coatings
By reference, analyze publishing papers on component
coatings based on Ti-Al alloys in the world [31-34, 45-47], the
results of target components are inherited from Korea Institute of
Industrial Technology [31]. In this thesis, the coatings are deposited
by magnetron sputtering using 02 targets, including:
- 01 target systerm with TiAl-X (X: V, B, Si) for depositing of
single – layer coatings
- 02 targets consist of TiAl-X (X: V, B, Si) target and Cr target
( > 99,9%) for depositing of multi-layer coatings.
4


The chemical composition of these targets is shown in table
2.1.
Table 2.1. Chemical composition of 02 targets.
Elements (% at.)

Ti

Al

X ( V, B, Si)

Target systerm 1

50

40

10

Target systerm 2

Cr

Size
ɸ75 x 8 mm

100

ɸ75 x 8 mm

2.1.1. Fabrication of targets
In this thesis, the targets are fabricated from 03 metal elements
(Ti, Al, X (Si, B, V)) by using powder metallugy technology. Size of
the fabricated target is ɸ75 x 8 mm.
2.1.2. Fabrication of coatings
2.1.2.1. Preparation of surface substrates

WC-Co substrates are ground and polished by SiC paper and
diamond solution, and then the substrate samples are continually
cleaned by ultrasonicvibrators in an alcohol or acetone environment
for 10 minutes to remove dirt from the surface of the samples.
2.1.2.2. Fabrication of single-layer TiAlXN coatings
After polishing and cleaning the surface of WC-Co and Si
(100) substrates, which introduced into vacuum chamber (1.5x10-3
Pa) of magnetron sputtering. The samples were subsequently fixed in
the substrate holder and continuously cleaned by Ar+ ion
bombardment for 30 minutes using the dc pulse discharge (Us = 600
V, PAr = 1.2 Pa, Is = 0.02 A) to further remove adsorbents and
residual oxides on the substrate surfaces.
Polished samples are deposited by DC magnetron sputtering
in the gas mixture of Ar/N2. The buffer layer of Cr or Ti metal is

5


deposited on the subtrate before deposition to increase the ahesion
strength between coating and substrate.
The deposited conditions of single-layer hard coatings
The parametters of magnetron sputtering processes deposited
coatings as follows:
o Deposition power: 200-350W
o Deposition pressure: 2.5; 5; 7; 10 mtorr
o Flow rate of N2 gas: 2; 4; 6; 8; 10 sccm (TiAlSiN coatings,
TiAlBN coatings); 4; 6; 8; 10 sccm (TiAlVN coatings), flow rate of
Ar gas: 36 sccm is fixed in during the magnetron sputtering.
o Distance of target and WC-Co substrate: 30-60 mm
o Deposition time: 30 minute

o Temperature of the substrate: Roon temperature (25oC)
o Target composition: Ti50Al40X10
After the deposition process, the coated samples were cooled down
in the chamber for 15 minute before venting to the atmospheric
pressure. All coated sample are analyzed and evaluated.
2.1.2.3. Fabrication of multi-layer TiAlX (Si, B)N/CrN coatings
Base on the optimal parameters in the fabrication of singlelayer coatings, the multi-layer coatings are depostited at the
condition as follows:
- Deposition power: 300 W
- Deposition pressure: 5 mtorr
- Distance of target and WC-Co (Si wafer) substrate: 50 mm
- Flow rate of working Ar gas: 36 sccm, flow rate of N2 gas: 6 sccm
(TiAlSiN/CrN) và 4 sccm (TiAlBN/CrN)
- Deposition time: TiAlX (Si, B)N: 5-15 minute, CrN: 2-6 minute
- Temperature of the substrate: Roon temperature (25oC)
6


CHAPTER 3. FABRICATION OF SINGLE-LAYER TiAlXN
(X: Si, B, V) COATINGS
3.1. Optinal parameters of magnetron sputtering processes
The basic parameteres consist of depostion power, pressure
and distance of target and WC-Co substrate are determined through
affects hardness of the coatings. The basic parameters are determined
as follows:
o Deposition time: 300 W
o Deposition pressure: 5 mtorr
Distance of target and WC-Co (Si wafer) substrate: 50 mm
3.2. Fabrication of single-layer TiAlSiN, TiAlBN and TiAlVN
coatings.

The nitride coatings are deposited by magnetron sputtering
using 02 gas, including: (i) working gas of Ar; (ii) active gas of N2.
Therein, the working gas of Ar motivated the ionization of atoms or
molecular and form plasma zone, active gas of N2 has effect on the
formation of nitride composition, which is formed on the target if
high energy ion bombarment or it is formed in moving time of
atoms, even it can be formed on the substrate after depostion.
As can be seen, the N2 gas flow rate affected on the
formation of nitride coatings and the properties of coatings. A
number of researches have been published showing the effect of N2
reactive gas content on the properties of coatings such as hardness,
friction coefficient, crystal particle size, phase composition [33,7778, 80-81]. Thus, the role of N2 gas is very important in forming
nitride coating.

7


Recognizing the importance of N2 gas, in the next section,
the thesis will focus on studying the effect of N2 gas flow on the
formation and properties of nitride coatings.
3.2.1. TiAlSiN coating
3.2.1.1. The effect of N2 gas flow rate of structure and chemical
composition of TiAlSiN coatings
The XRD patterm of TiAlSiN coatings deposited at 6 sccm N2
gas flow rate shows perfect face centered cubic (fcc) structure
(acorrding to stand JCPDS No: 38-1420) with 02 peaks of TiN (111)
and TiN (220). TiN (111) peak has highest intensity at 36,6o,
however, when N2 gas flow rate increases up to 8 sccm, the intensity
of TiN (111) peak decreases and the intensity of TiN (200) peak
increases gradually. This trend occurs for the coating deposited at 10

sccm N2 gas flow rate. In addition, a TiN (311) peak is appeared at
this N2 gas flow rate.

Figure 3.1. The XRD patterm of TiAlSiN coatings deposited at
different N2 gas flow rate.
The TiAlSiN coatings with fine particle size are indicated at N2 gas
flow rate of 2, 4 and 6 sccm. Moreover, the SEM image also shows
these pores on the surface coatings at N2 gas flow of 2 and 4 sccm.
8


This suggests that the density of TiAlSiN coating is not high. In
addition, easy to observe, the particle size of coatings increases when
increasing N2 gas flow rate from 2 to 10 sccm.

Figure 3.2. Surface morphology and thickness of TiAlSiN
coatings at different N2 gas flow rate.
The cross-section and thickness of TiAlSiN coatings on insert
images, which can be seen that at the low N2 gas flow rate (2, 4, and
6 sccm), cross-section surface of the coatings are smoother and no
column than that of the coatings deposited at higher N2 gas flow rate
(8 and 10 sccm). This result is due to the increase in the crystal
particle size of faricated coatings. Meanwhile, the thickness of the
coatings was decreased form 4.32 µm to 3.58 µm when the N2 gas
flow rate was increased from 2 sccm to 10 sccm.
3.2.1.2. Effect of N2 gas flow rate on the hardness of TiAlSiN
coatings
The results showed that the hardness of the coatings increased
from 24 GPa to 33.5 GPa when N2 gas flow increased from 2 sccm
to 6 sccm. The hardness of the coatings tends to decrease when the

N2 gas flow continually increase from 8 to 10 sccm. Elastic modulus
9


results tend to be similar to hardness values. When N2 gas flow
increases from 2 to 6 sccm, the elastic module increases from 267 to
346 GPa. The elastic modulus of the coatings continually decreases
with increasing N2 gas flow rate.

Figure 3.3. Effect of N2 gas flow rate on the hardness of coatings
3.2.1.3. Effect of N2 gas flow on the friction coefficient and wear of
TiAlSiN coatings
a) Dry condition

Figure 3.4. The friction coefficient of the coatings at different N2 gas
flow rate.
10


At N2 gas flow of 2 sccm, the stability can be seen during the
sliding process with an average friction coefficient value of ~ 0.74.
The average friction coefficient increased from 0.78 to 0.795 at the
N2 gas flow of 4 and 6 sccm, respectively. The friction coefficient of
the coatings continually increased with increasing the N2 gas flow.
Moreover, the unstableness in during the sliding is also increased.
This is indicated in the unstable increase and decrease for deposit at
N2 gas fow of 8 and 10 sccm.
b) Oil condition
The average friction coefficient of the coatings at low N2 gas
flows at 2, 4, 6 sccm ranges from 0.08 - 0.1 and increases to above

0.1 at N2 gas flow of 8 sccm and 10 sccm. Specifically, the lowest
friction coefficient is obtained at the N2 gas flow of 2 sccm and the
highest is obtained at the N2 gas flow of 10 sccm
3.2.1.4. Effect of N2 gas flow rate on the adhesion strength of
TiAlSiN coatings
In this stuty, adhesion strength is determined by Scratch test
method with a diamond tip attached to the stylus. The load value of
the diamond tip is increased gradually from 0 N to 30 N or 50 N and
when load value is reached, the coatings starts to appear peeling off
the surface substrate, which is called the critical load.
The critical load value increases from 18.3 N to 23.9 N when
increase in the N2 gas flow rate from 2 to 6 sccm. If the N2 gas flow
rate continues to increase up to 8 sccm, the critical load would be
decreased. The other hand, adhesion strength between the coating
and the substrate will be decreased.
The adhesion strength between the coating and the substrate is
shown in detail on the Table 3.2
11


Table 3.2. Adhesion strength at diffirent N2 gas flow and
using bufferlayer.
2ccm
Critical
load(N)

18.3

4sccm 6 sccm
20.7

23.9

8 sccm
19.9

10sccm Cr bufferlayer
17.6

36.5

3.2.2. TiAlBN coatings
3.2.2.1. The effect of N2 gas flow rate of structure and chemical
composition of TiAlBN coatings
The coated sample at 4 sccm N2 gas flow rate, there are three
peaks of TiN which is observed at the posistion of 36.6o, 61.8o and
77.9o, corresponding to the crystal orientation (111), (220) and (222),
respectively in the pattern. According to JCPDS standard No: 381420, TiN with face-centered cubic structure (FCC). Moreover, XRD
diffraction patterns also indicated the intensity and the position of
peaks varying with N2 gas flow rate. The intensity of TiN (111) is
highest at N2 gas flow of 4 sccm. If N2 gas flow rate continues to
increase above 4 sccm, the intensity of TiN (111) peak will be
decreased and the lowest intensity at 10 N2 gas flow rate.
3.2.2.2. Effect of N2 gas flow rate on the hardness of TiAlBN coatings
As can be seen that the smallest hardness is obtained at N2 gas
flow rate of 2 sccm. When the increasing N2 gas flow rate, the
hardness of the TiAlBN coatings increase and reaches the maximum
value (~ 41 GPa) at N2 gas flow of 4 sccm. If N2 gas flow rate
continues to increase upto 6 and 10 sccm, the hardness of the
coatings tends to decrease gradually.

Results of elastic modulus tend to be similar to the hardness
values. The elastic modulus increases from 207 GPa to 396 GPa
12


when N2 gas flow rate increases from 2 to 4 sccm. If the N2 gas flow
rate increases continually, elastic modulus of the TiAlBN coating
will be reduced.
3.2.2.3. Effect of

N2

gas flow on the friction coefficient and wear of

TiAlBN coatings
a) Dry condition
Friction coefficient results of the TiAlBN coating indicated
that the friction coefficient of the coating increases when the
incresing N2 gas flow rate. At low N2 gas flow rate (2 - 6 sccm), the
friction coefficient of the coating is stable in during sliding distance.
However, when the increasing N2 gas flow rate, the friction
coefficient of the coatings shows the oscillation in during sliding
distance. On the insert figure, the results indicated that friction
coefficient of the coatings increase 0.46 to 0.69 when the increasing
N2 gas flow rate from 2 to 10 scc.
b) Oil condition
The results indicated that the friction coefficient of the
coatings increases from 0.053 to 0.054 when the increasing N2 gas
flow rate from 2 to 4 sccm. The N2 gas flow rate continues to
increase from 6 to 10 sccm, the friction coefficinent of the coating

would be increased from 0.98 to 0.135.
3.2.2.4. Effect of N2 gas flow rate on the adhesion strength of TiAlBN
coatings
The results indicated that the highest adhesion strength of the
caoting is obtained in the range of 4 to 6 sccm, corespoding to
critical load from 19.1 N to 20.3 N. If N2 gas flow rate continues to
increase above 6 sccm, the critical load tends to decrease. Moreover,

13


when Cr metal is used as bufferlayer, the adhesion strength of the
coatings is increased for two times, compared to no-bufferlayer.
Table 3.5. Adhesion strength at diffirent N2 gas flow and
using bufferlayer.
2ccm
Critical
load(N)

17.8

4sccm 6 sccm
19.1

20.3

8 sccm
15.6

10sccm Cr bufferlayer

16

42.4

3.2.3. TiAlVN coatings
3.2.3.1. The effect of N2 gas flow rate of structure and chemical
composition of TiAlVN coatings
Only one TiN (220) with fcc (face centered cubic) or TiAlVN
at 4 sccm N2 gas flow rate. When the increasing N2 gas flow rate of 6
sccm, three TiN peaks with fcc structure, including TiN (111), (200)
and (220). If N2 gas flow rate continues to increase upto 8 and 10
sccm, the obtained coatings have dual phase which consist of hcp
phase – AlN and fcc phase – TiN. The other hand, the obtained
coatings have single phase at low N2 gas flow rate (4-6 sccm) and
dual phase (fcc + hcp) at higher N2 gas flow rate (8-10 sccm).
3.2.3.2. Effect of N2 gas flow rate on the hardness of TiAlVN coatings
The hardness of the coatings increases from 30.6 GPa to 36.5 GPa
when N2 gas flow rate increased from 4 to 6 sccm. If N2 gas flow rate
continues to increase up to 8 and 10 sccm, the hardness of the
coating tends to decrease.
3.2.3.3. Effect of N2 gas flow on the friction coefficient and wear of
TiAlVN coatings
a) Dry condition

14


The friction coefficient of the coatings exhibited the same
tendency in the initial stage. After that, the friction coefficient tends
to decrease gradually for all the coatings, except for the coating

deposited at 10 sccm N2 flow rate. The lowest friction coefficient was
observed in the coating deposited at the N2 flow rate of 4 sccm (~
0.52). When the N2 gas flow rate increases from 6 to 8 sccm, average
friction coefficient of the coatings also increased from 0.58 to 0.73
and reaching the highest friction coefficient for the coating deposited
at the N2 flow rate of 10 sccm.
b) Oil condition
The results indicated that friction coefficient of the coatings
increased from 0.094 to 0.143 in oil condition when the N2 gas flow
rate increases from 4 to 10 sccm. Compared to dry condition, the
friction coefficient of the coatings in oil condition has reduced from
5 to 6 times.
c) Effect of heating temperature on the friction coefficient of the
coatings
The friction coefficient of the coating increases when the
coatings are heated at 500 oC. The result was attributed to the
formation of Al2O3 on the surface coating or the increase in the grain
size of the coatings while the Magnéli phases have not formed yet at
this temperature. When the temperature increases up to 600oC and
700oC, the friction coefficient of the coating would be decreased to
be 0.45 and 0.38, respectively.
3.2.3.4. Effect of N2 gas flow rate on the adhesion strength of TiAlVN
coatings
The results indicated that the highest adhesion strength of the
coating (24.4 N) is obtained at the N2 gas flow rate of 6 sccm. The
15


lowest adhesion strength of the coating (18.3 N) is observed at the N2
gas flow rate of 10 sccm. When Cr or Ti metal are used as

bufferlayer, the adhesion strength of the coatings is increased from
1.5 to 2 times, compared to no-bufferlayer.
Table 3.8. Adhesion strength at diffirent N2 gas flow and using
Cr or Ti as bufferlayer.
4sccm 6 sccm
Critical
load
22.1
24.4
(N)

8 sccm

10sccm Cr buffer

19.9

18.3

Ti buffer

41

47.2

3.2.4. The comparision of mechanical properties of the coatings:
TiAlSiN, TiAlBN and TiAlVN
Table 3.9. Results of mechanical properties of TiAlSiN, TiAlBN &
TiAlVN
Friction coefficient

Elastic
Hardness
modulus
(GPa)
(GPa)

Adhesion
strength

NoDry
Oil
buffe
condition condition
layer

TiAlSiN

33.5

346

0.795

0.105

23.4

TiAlBN

41

396

0.52

0.075

19.1

372

0.58;
0.45 at
600oC)
and 0.38
at 700oC

TiAlVN

36.5

16

0.112

24.4

Buffer
layer
36.5

(Cr)
42.4
(Cr)
41
(Ti);
47.2
(Cr)


CHAPTER 4. FABRICATION OF TiAl-X(Si, B)N/CrN
MULTILAYER HARD COATINGS
TiAl-X (Si, B) N / CrN multilayer hard coating are deposited
by dc magnetron sputtering on Si substrate and WC-Co alloy
substrate, using two targets of Ti50Al40X10 (X: Si,B) and Cr. The
basic parameters of sputtering include: Power (300W), pressure (5
mtor), distance between target and substrate (50 mm), Ar gas flow of
36 sccm. Meanwhile, N2 gas flow of 6 sccm for TiAlSiN/CrN
multilayer coating and 4 sccm for TiAlBN/CrN coatings. Deposition
time was changed to investigate the thickness of single coatings as
follows: TiAlSiN, TiAlBN: 10-15 minutes and CrN: 1-3 minutes.
4.1. TiAlSiN/CrN multilayer coatings
4.1.1. Structure of TiAlSiN/CrN coatings
4.1.1.1. Phase structure

Figure 4.1. XRD patterns of TiAlSiN/CrN multilayer coating (a);
CrN single-layer coating (b); TiAlSiN single-layer coating (c).
The XRD patterns results of the multi-layer TiAlSiN/CrN coating
(Figure 4.1c) show that the peaks of the multi-layer coating are
combinated with TiAlSiN and CrN single-layer coating. However,
17

the position of the peaks is shifted, compared to the peaks of TiN and
CrN. It can be contributed the replacement of Cr atoms to the
position of Ti atoms with different atomic radii causes the dislocation
of lattice parameters.
4.1.1.2. Morphological structure

Figure 4.2. Surface morphology and cross-section of TiAlSiN/CrN
multi-layer coating :(a,d)- 2 layers; (b-e)- 4 layers; (c-f): 12 layers.
When the bilayer period thickness of TiAlSiN-CrN coatings
decreases, the particle size increases. The other hand, bilayer period
of TiAlSiN-CrN coatings increases when the particle size would be
decreased.
4.1.2. Hardness and elastic modulus of TiAlSiN/CrN multilayer
coatings
4.1.2.1. Effect of bilayer period on the hardness of the coatings
The hardness results is a range from 21 to 31.2 GPa.
Maximum hardness values were determined at 245 nm bilayer period
thickness (TiAlSi-127 nm & CrN-118 nm). When the bilayer period

18


thickness of the coatings increases, the hardness of the film tends to
decrease.
4.1.2.2. Effect of layers on the hardness of the coatings
When increasing the number of layers from 2 to 12 layers, the
hardness of the coating increases rapidly from 18.3 to 31.4 GPa. If
the number of layers continues to increase, the hardness value of the

TiAlSiN/CrN multi-layer coatings does not change significantly.
4.1.3. Friction coefficient of TiAlSiN/CrN multilayer coatings
The average friction coefficient of WC-Co alloy substrate is
0.74, while the average friction coefficient of TiAlSiN and CrN
monolayer coatings is 0.81 and 0.66, respectively and TiAlSiN/CrN
multilayer coatings is 0.71.
4.1.4. Adhesion strength of TiAlSiN/CrN multilayer coatings
The adhesion strength between the coatings and substrate is
significantly improved by using buffer layer. When Cr as buffer
layer is not used, the critical load is obderved at 26.3N, while the Cr
metal as buffer layer is used for the deposition of TiAlSiN/CrN
multilayer coatings, the critical load value is indicated above 30N.
4.2. TiAlBN/CrN multilayer coatings
4.2.1. Structure of TiAlBN/CrN multilayer coatings
4.2.1.1 Phase struture
The results showed that the peaks of the multi-layer coating
(Figure 4.9c) is combinated with the peaks of monolayer coatings.
4.2.1.2. Morphological structure
When the bilayer period thickness decreases from (815 + 663
nm) to (79 + 86 nm), the particle size of the coatings also decreases
(Figure 4.10 a-c). It can be attributed on the TiAlBN coatings which
have fine particle size, compared to CrN coating, when the bilayer
19


period thickness is thin, the surface of the coatings is affected by the
both TiAlBN and CrN.
4.2.2. Hardness and elastic modulus of TiAlBN/CrN multilayer
coatings
4.2.2.1. Effect of bilayer period on the hardness of the coatings

The hardness of the coating increases from 28.2 to 33.8 GPa
when the bilayer period thickness increases from 165 to 232 nm. If
the bilayer period of the coatings continues to increases, the hardness
of the film tends to decrease.
4.2.2.2. Effect of layers on the hardness of the coatings
When increasing the number of layers from 2 to 14 layers, the
hardness of the coating increases rapidly from 16.5 to 33.8 GPa. If
the number of layers continues to increase, the hardness value of the
TiAlBN/CrN multi-layer coatings does not change significantly.
4.2.3. Friction coefficient of TiAlBN/CrN multilayer coatings
The lowest friction coefficient is indicated for TiAlBN
coatings, compared to TiAlBN/CrN multilayer coatings is 0.71, CrN
monolayer coatings is 0.81 and WC-Co substrate is 0.75.
4.2.4. Adhesion strength of TiAlSiN/CrN multilayer coatings
The maximum adhesion strength between the coatings and
substrate without buffer layers, the critical load is obderved at 24.7
N, while the Cr metal as buffer layer is used for the deposition of
TiAlBN/CrN multilayer coatings, the critical load value is indicated
above 30N.

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CONCLUSIONS
1. By self-fabricating of the multi-element targets, the TiAlXN (X:
Si, B, V) single-layer coatings have been successfully fabricated on
WC-Co alloy substrates by magnetron sputtering method, including
the steps: (i) Fabrication of Ti50Al40X10 (X: Si, B, V) multi-element
targets by advanced powder metallurgy processes, (ii) preparation of
WC-Co alloy surface substrates, (iii) dc magnetron sputtering. In

particular, the basic parameters of sputtering process are as follows:
- Power : 300 W
- Pressure: 5 mtor
- Distance of target and substrate: 50 mm
- Ar gas flow rate: 36 sccm
- N2 gas flow rate: 2 to 10 sccm
- Deposition time: 30 phút
2. With respect to single layer coatings, the effects of the N2 gas flow
rates on the properties of three kind of the TiAlXN coatings have
been investigated by using Ti50Al40X10 (X:Si, B, V) target systerm.
Namely, the optimal N2 gas flow rate is obtained at 4 and 6 sccm for
TiAlBN and TiAlSiN, TiAlVN, respectively.
3. The hardness of fabricated coating is compared with the hardness
of previous literatures, we can be concluded that the fabricated
TiAlBN coatings have higher hardness and low friction coefficient
than the previous literatures in the same fabrication processes. The
TiAlSiN and TiAlVN coatings are fabicated with hardness and
friction coefficient equivalent to those previous literatures
After heating TiAlVN coatings above 600oC, the friction coefficient
of the heated coatings is lower than that of non-heated coating due to
the formation of Magnéli phases.
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5. Cr metal as buffer layers, adhesion strength of three kinds of the
coatings increases from 1.5 to 2 times, compared to no-buffer layer.
It shown that the adhesion strength of three kinds of the coatings
with Ti (for TiAlVN coating) or Cr metal as buffer layer have the
critical load of above 30 N.
6. The bi-layer period thickness and a number of layers of

TiAlSiN/CrN and TiAlBN/CrN multilayer coatings are investigated.
Mamely, the highest hardness of TiAlSiN/CrN multilayer coatings is
obtained at the bi-layer period of 245 nm (TiAlSiN: 127 nm and
CrN: 118 nm) and 12 layers, the highest hardness of TiAlBN/CrN
multilayer coatings is obtained at the bi-layer period of 232 nm
(TiAlSiN: 127 nm and CrN: 118 nm) and 14 layers.
NEW DISTRIBUTRIONS OF THESIS
1. The Ti50Al40X10 (X: Si, B, V) multi-element targets have been
fabricated by powder metallurgy processes. By using the fabricated
targets, single layer coatings of TiAlXN (X: Si, B, V) and multilayer
coatings of TiAlXN/CrN (X: Si, B) have been fabricated by dc
magnetron sputtering on WC-Co substrates. Later investigation
indicated that the coatings shows the same or even better properties,
compared to previous published works.
2. The effects of N2 flow rate on structure and mechanical
properties of three kinds of the TiAlXN (X: Si, B, V) coatings were
studied and evaluated. Especially, the optimal Ar/N2 gas ratio of 36
sccm/6 sccm and 36 sccm/4 sccm has been identified for TiAlSiN,
TiAlVN coatings and TiAlBN coating, respectively.

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3. Optimal bilayer period thickness and a number of layers of
TiAlX(Si,B)N/CrN multilayer

coatings

were

determined

for

achieving excellent properties of the coatings.
PUBLICATION LIST
I.

Internaltional journal

1. Van Duong Luong, Doan Dinh Phuong, Phan Ngoc Minh,
Kyoung Il Moon, Influence of Nitrogen Gas Flow on the
Hardness and the Tribological Properties of a TiAlBN Coating
Deposited by Using a Magnetron Sputtering Process, Journal of
the Korean Physical Society, 70(10) (2017) 929-933. (SCIIF:0.5).
2. Doan Dinh Phuong, Van Duong Luong, Phan Ngoc Minh, Hyun
Jun Park, Kyoung Il Moon, Microstructure, mechanical and
tribological behavior of the TiAlVN coatings, Acta Metallurgica
Slovaca, 24 (4) (2018), 266-272. (E-SCI)
II. Domestic journal and international workshop
3. Van Duong Luong, Doan Dinh Phuong, Nguyen Quang Huan,
Do Thi Nhung, Phan Ngoc Minh, Kyoung Il Moon, Synthesis of
the TiAlVN coating deposited by magnetron sputtering using a
single target, Hội nghị vật lý chất rắn và khoa học vật liệu toàn
quốc lần thứ X, 2017 tại T.P. Huế (ISBN: 978-604-95-0326-9).
4. Van Duong Luong, Dinh Phuong Doan, “Structure and
properties of the TiAlBN coatings” The 5th Asian Materials
Data Symposium, Oct 30th - Nov 02nd 2016, Hanoi, Vietnam,
(ISBN: 978-604-913-500-2).
5. Van Duong Luong, Dinh Phuong Doan “Study on Fabrication of

Multilayer TiAlSiN/CrN Coating on WC-Co Substrate by DC
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Magnetron Sputtering” The 13th Asian Foundry Congress (AFC
13), 2015 (ISBN: 978-604-938-550-6).
6. Van Duong Luong, Dinh Phuong Doan, Kyoung Il Moon, Won
Beom

Lee

“Synthesis

and

characteristics

of

multilayer

TiAlSiN/CrN coatings” Proceedings of International Workshop
on Advanced Materials Science and Nanotechnology, IWAMSN
2014
7. Lương Văn Đương, Nguyễn Văn Luân, Trần Bảo Trung,
Nguyễn Văn An “Nghiên cứu công nghệ phủ màng siêu cứng đa
lớp TiAlSiN/CrN trên nền hợp kim cứng WC-Co bằng phương
pháp phún xạ” Tuyển tập hội nghị khoa học thanh niên Viện
Hàn lâm Khoa học và Công nghệ Việt Nam lần thứ 13, 2014
(ISBN: 978-604-913-309-1).

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