Magnetron sputtering is a flexible technique and allows producing a significant amount of types of coatings. Within the frame of present work, Ti-C-O-N thin films were deposited onto high-speed steel (AISI M2), substrates by reactive dc magnetron sputtering in a laboratory-size deposition system. It consisted of two vertically opposed rectangular magnetrons, in a closed field configuration. The films were prepared using dc power source on a titanium target (99.6 at.%). A gas atmosphere composed of argon (working gas), acetylene and nitrogen/oxygen (17:3) reactive mixture was used for the depositions. In terms of structure, the samples produced only with ethylene and argon flow reveal a TiC structure (NaCl type). The decrease of Ф(C2H2)/Ф(O2+N2) induces amorphisation, but TiC structure, with possible N and O inclusions, is still detected. In terms of tribological aspects, the static friction coefficient and roughness (Rz) were analyzed and discussed depending of composition and structure

Alexandru MUNTEANU

Camelia OLTEANU

Cristian IONESCU

Daniel MUNTEANU

Filipe VAZ

Luis CUNHA

The Annals of “Dunarea de Jos” University of Galati Fascicle IX Metallurgy and Materials Science

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THE ANNALS OF “DUNAREA DE JOS” UNIVERSITY OF GALATI. 
FASCICLE IX. METALLURGY AND MATERIALS SCIENCE 
N0. 2 – 2007, ISSN 1453 – 083X 
 
 
 
 
STRUCTURAL AND TRIBOLOGICAL ASPECTS ON Ti(C,O,N) 
MAGNETRON REACTIVE SPUTTERED THIN-FILMS 
 
Daniel MUNTEANU1, Camelia OLTEANU1, Cristian IONESCU1, 
Alexandru MUNTEANU1,Filipe VAZ2, Luis CUNHA2  
1Transilvania University of Brasov, Romania 
2Universidade do Minho, Guimaraes, Portugal 
email: muntean.d@unitbv.ro 
 
ABSTRACT 
 
Magnetron sputtering is a flexible technique and allows producing a 
significant amount of types of coatings. Within the frame of present work, Ti-C-O-N 
thin films were deposited onto high-speed steel (AISI M2), substrates by reactive dc 
magnetron sputtering in a laboratory-size deposition system. It consisted of two 
vertically opposed rectangular magnetrons, in a closed field configuration. The 
films were prepared using dc power source on a titanium target (99.6 at.%). A gas 
atmosphere composed of argon (working gas), acetylene and nitrogen/oxygen 
(17:3) reactive mixture was used for the depositions. In terms of structure, the 
samples produced only with ethylene and argon flow reveal a TiC structure (NaCl 
type). The decrease of Ф(C2H2)/Ф(O2+N2) induces amorphisation, but TiC 
structure, with possible N and O inclusions, is still detected. In terms of tribological 
aspects, the static friction coefficient and roughness (Rz) were analyzed and 
discussed depending of composition and structure. 
  
KEYWORDS: magnetron, sputtering, roughness, friction 
 
 
1. Introduction 
 
During the last years, there have been several 
attempts to improve the properties of diamond-like 
carbon (DLC) films by the addition of other elements, 
such as silicon, nitrogen and varios metals. Many 
modifications have been tried and the addition of, for 
example, nitrogen, has shown to reduce the inner 
stress, electrical resistivity and friction coefficient [1]. 
In the same manner, oxygen has always been looked 
upon as an interesting element in thin film materials, 
not only because of its high reactivity with most 
metals, but also due to the changes that induces in 
chemical bonding states, and in the material’s 
electrical, optical, and mechanical characteristics. 
Titanium carbonitride coatings Ti(C,N), are used 
mostly to improve tool life by combining the 
properties of TiN and TiC. The advantages of these 
coatings over other coatings material, stem from its 
superior friction behaviour in contact with steel, high 
hardness and residual stress [2]. Because of their low 
friction, the coating is durable at slow cutting speeds 
especially [3]. The combined effect of low friction 
behaviour and high residual stress help preventing 
cutting-edge deformation for high speed steels, and 
on carbides reduces the cutting-edge chipping. 
Moreover, it provides excellent resistance to wear due 
to the coating high hardness [4]. Adding oxygen to 
the film is a possibility to improve the coating’s 
characteristics. The presence of oxygen allows the 
tailoring of films properties between those of 
metallic-like carbides and those of the corresponding 
ion oxides, and from these a wide range of 
applications. It is expected that the Ti(C,N,O) films 
will exhibit good resistance to friction wear and 
corrosion due to the small atomic size of oxygen, 
witch creates high hardness and a compressive stress 
state [2,5,6].  
In the present paper the Ti(C,N,O) thin films, 
with various compositions, were deposited in a closed 
field unbalanced reactive d.c. magnetron sputtering 
system, varying the Ф(C2H2)/Ф(O2+N2) flow. 
Sputtering is one of the most commonly used 
methods for the deposition of thin films. Its 
popularity stems from simplicity of the physical 
processes involved, versatility of the technique, and 
flexibility for alteration and customisation. It is 
widely used in the semiconductor, photovoltaic, 
recording and automotive industries. In addition, 
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THE ANNALS OF “DUNAREA DE JOS” UNIVERSITY OF GALATI. 
FASCICLE IX. METALLURGY AND MATERIALS SCIENCE 
N0. 2 – 2007, ISSN 1453 – 083X 
 
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specialised applications of sputtering in the 
manufacturing of sensors, decorative glasses, optical 
devices, etc, are also very common. 
       High melting point materials like ceramics and 
refractory metals, which are hard to deposit by 
evaporative techniques, are easily deposited using 
sputtering. Sputtering techniques range from a simple 
dc glow discharge, which is limited to the sputtering 
of conductive targets, to RF sputtering where any 
target regardless its conductivity can be sputtered, to 
a more sophisticated ion beam sputtering (IBS) in 
which very controlled deposition of material is 
possible.  
In terms of deposition rates, there are sputtering 
techniques now available, which rival evaporation or 
other higher deposition rate techniques. The purpose 
of using a magnetic field in a sputtering system is to 
make efficient use of the electrons and cause them to 
produce more ionisation [7]. 
         Taking into account the fact that unbalanced 
magnetron (the magnetic field lines does not all close 
on the cathode surface) sputtering was used in this 
paper, an image is presented in figure 1. 
 
 
 
Fig. 1. Unbalanced magnetron [8]. 
 
2. Experimental details 
 
Within the frame of present work, Ti-C-O-N 
thin films were deposited onto high-speed steel (AISI 
M2), substrates by reactive dc magnetron sputtering 
in a laboratory-size deposition system. It consisted of 
two vertically opposed rectangular magnetrons, in a 
closed field configuration.  
The films were prepared using dc power source 
on a titanium target (99.6 at.%). A gas atmosphere 
composed of argon (working gas), acetylene and 
nitrogen/oxygen (17:3) reactive mixture was used for 
the depositions (as shown in table 1).  
The deposition was carried out using a 
laboratory-size deposition system. During deposition 
the working pressure was approximately constant at 
0.4 Pa and the bias voltage was -70V. In all the cases 
the deposition time was kept at 3600s. 
 
 
Table 1. Gas flows (experimental variants) 
 
Gas flow [%] Samples C2H2 O+N Ar 
TiCON 1 3 11 12 
TiCON 2 5 8 12 
TiCON 3 2 16 12 
TiCON 4 2 8 15 
TiCON 5 2 20 15 
TiCON 6 1.5 6 15 
TiCON 7 1.5 10 15 
TiCON 8 1.5 18 15 
TiCON 9 1.5 25 12 
TiCON 10 1.5 0 15 
 
The atomic composition of the as deposited 
samples was measured by electron probe 
microanalysis (EPMA) in a Cameca SX-50 apparatus. 
The crystallographic structure was investigated by X-
ray diffraction (XRD) in the Bragg-Bretano 
configuration, using monochromatic Cu Kα radiation. 
Atomic Force Microscopy (AFM) - 5x5μm line 
scans was used for roughness characterization. The 
static friction coefficient values were established, for 
each sample, in different-friction condition, using a 
plane fixed half-couple manufactured by heat 
treatable steel (AISI B7), in annealing heat-treatment 
conditions. The friction plane fixed half-couple had a 
lot of roughness Rz values, comprised between 0.4 
and 2.5 μm. The work with different roughness values 
of fixed plane half-couple is important in order to 
could take into consideration the possible influence of 
sliding – plane roughness on friction process and to 
have finally an average value of static friction 
coefficient.  
Before the tribological tests, the samples were 
first degaussed and then alkaline cleaned and wiped. 
The fixed half-couple was also degaussed and 
periodically alkaline cleaned and wiped. According to 
the method description, 10 friction tests were 
performed for each sample on each half-couple: 5 in 
one direction and 5 abeam, such as the one-way 
roughness would not influence the moving of the 
samples. In each case, the utmost values were 
eliminated. The environmental conditions of 
tribological tests were: T = 23.5oC and 63% humidity. 
 
3. Results and discussion 
 
The measured values of the friction coefficient 
vary between 0.2 and 0.39, while the roughness 
values range from 0.13µm  to a maximum of 0.21µm. 
The results showed a correlation between the friction 
coefficient and roughness evolution with the growth 
of the C2H2/(O+N) flows ratio (figure 2).  
 
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FASCICLE IX. METALLURGY AND MATERIALS SCIENCE 
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A simultaneous growth of the friction 
coefficient and roughness can be observed up to a 
0.25 value of the C2H2/(O+N) ratio, then the 
parameters register an  abrupt decrease on the flow 
value interval from 0.25 to 0.3. After this critical 
value of the C2H2/(O+N) flows ratio, the two 
parameters evolution is stable. 
As a conclusion we could underline the existing 
dependence between static friction coefficient (µ) and 
roughness (Rz); these parameters are both increasing 
or decreasing on a certain interval of flow values. 
        
        
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Fig. 2. Influence of gas flow ratio on friction coefficient and roughness. 
 
In terms of the chemical composition, the 
results showed that, at 0.25 gas flow ratio the carbon 
percentage moves from an abrupt growth to a slower 
growth. The amount of titanium present an 
emphatically decrease around 0.25 gas flows ratio, 
while the oxygen starts growing and the nitrogen 
percentage is changeless (steady) for a short interval 
and starts a slow decrease around 0.3 gas flow ratio 
(figure 3). 
From a tribological point of view, we can say 
that the growth of the oxygen percentage it is linked 
to the decrease of the roughness and friction 
coefficient values. Also, a decrease in the titanium 
percentage leads to a decrease of roughness and 
friction coefficient. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Fig. 3. Corelation between concentration and gas flow ratio. 
 
4. Conclusions 
 
TiCON thin-films were prepared by reactive 
magnetron sputtering on high-speed steel (AISI M2) 
substrate, using a mixture of C2H2 and (N2+O2) as 
reactive gases. The static friction coefficient and Rz 
roughness seams to have the same behaviour with the 
increasing of carbon percentage in the film. The 
maximum values for friction coefficient were 
registered at about a value of 0.25 for C2H2/(O+N) 
 
0
0.05
0.1
0.15
0.2
0.25
0.06 0.08 0.1 0.12 0.15 0.25 0.25 0.27 0.62
Gas flow ratio C2H2/(N+O)
Rz
 [m
ic
ro
m
et
er
s]
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
St
at
ic
 fr
ic
tio
n 
co
ef
fic
ie
nt
Rz roughness Static friction coefficient
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THE ANNALS OF “DUNAREA DE JOS” UNIVERSITY OF GALATI. 
FASCICLE IX. METALLURGY AND MATERIALS SCIENCE 
N0. 2 – 2007, ISSN 1453 – 083X 
 
 
flows ratio, zone where is supose that the TiC cubic 
lattice begins to dezorganize.  In terms of 
concentrations, this point (0.25) marks a tendency for 
keeping almost constant the C and N concentrations 
in the films with the increasing of  C2H2/(O+N) flows 
ratio. 
 
References 
 
[1] Fernandes A., Carvalho P., Vaz F., S. Lanceros-Méndez  
A.V. Machado, N.M.G. Parreira , J.F. Pierson , N. Martin,  
Property change in multifunctional TiCxOy thin films: Effect of the 
O/Ti ratio, Thin Solid Films 515 (2006) 866–871,  
www.sciencedirect.com, 2006; 
[2] J.H. Hsieh , W. Wu , C. Li , C.H. Yu , B.H. Tan, Deposition 
and characterization of Ti(C,N,O) coatings by unbalanced 
magnetron sputtering, Surface and Coatings Technology 163 –164 
(2003) 233–237, www.elsevier.com/locate/surfcoat, 2003; 
[3] Baravian G., Sultan G., Damond E., Detour H., Surf. 
Coat.Technol. 76/77 (1995) 687. 
[4] Knotek O., Loffler F., Kramer G., Surf. Coat. Technol. 
61(1993) 320. 
[5] Y. Shi, H. Peng, Y. Xie, G. Xie, C. Zhao, Surf. Coat. 
Technol.132 (1998) 26. 
[6] Stanishevsky A., Lappalainen R., Surf. Coat. Technol. 
123(2000) 101. 
[7]  Munteanu D., Vaz F.,.Munteanu A, Schreiner A.,.Ionescu 
C,.Olteanu C,.Borcea B, Straturi subţiri de tip Ti-Si-C şi Ti-O-C 
obţinute prin pulverizare reactivă în sistem magnetron, Editura 
Universităţii Transilvania, Brasov, 2007; 
[8] www.pvd-coatings.co.uk 
 
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Structural and Tribological Aspects on Ti (C,O,N) Magnetron Reactive Sputtered Thin-Films

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Structural and Tribological Aspects on Ti (C,O,N) Magnetron Reactive Sputtered Thin-Films

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