Wüest M. 51 Wykes M. 82 Yamaguchi M. 17 Ybarra G. 129 Yubero F ...
Wüest M. 51 Wykes M. 82 Yamaguchi M. 17 Ybarra G. 129 Yubero F ...
Wüest M. 51 Wykes M. 82 Yamaguchi M. 17 Ybarra G. 129 Yubero F ...
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JUNE 28 WEDNESDAY MORNING<br />
JS2-WeM-OR.3 TRIBOLOGICAL CHARACTERIZATION OF TUNGSTEN NITRIDE<br />
COATING AT ELEVATED TEMPERATURE. T. Polcar, N.M.G. Parreira and A. Cavaleiro a *.<br />
ICEMS – Grupo de Materiais e Engenharia de Superfícies, Faculdade de Ciências e Tecnologia da<br />
Universidade de Coimbra – Pólo II, 3030-201 Coimbra, Portugal. * To whom all correspondence<br />
should be addressed (albano.cavaleiro@dem.uc.pt)<br />
Transition metal nitrides are known for the unique combination of excellent mechanical properties<br />
(hardness and Young’s modulus), high melting point, good chemical stability and high electrical<br />
conductivity. However, tungsten nitrides still stand aside of the main attention, particularly compared<br />
to titanium or chromium nitrides. The first studies of tungsten nitrides thin films were performed, basically,<br />
for electronic applications such as, semiconductors or diffusion barriers. In the 90´s, W-N<br />
coatings were started to be studied for mechanical applications and further studies were performed<br />
on the addition of different elements (e.g. W-Ti-N and W-Si-N) in order to improve their mechanical<br />
properties. There are only few studies dealing with tribological properties of tungsten nitrides and<br />
showing their good wear resistance. In our previous study, tungsten nitride coatings with different nitrogen<br />
content showed excellent wear resistance in case of sliding against ceramic Al 2 O 3 and Si 3 N 4<br />
balls. However, many engineering applications require good tribological properties, particularly wear<br />
resistance, at elevated temperature. Thus, the present study is focused on the tribological behaviour<br />
(friction coefficient and wear rate) of tungsten nitride coating at temperature in the range 20 - 600°C.<br />
The structure, hardness, friction and wear of tungsten nitride coating prepared by dc reactive magnetron<br />
sputtering were investigated. The tribological tests were performed on a pin-on-disc tribometer<br />
in terrestrial atmosphere with Al 2 O 3 balls as sliding partner. The wear tracks and the ball wear scars<br />
were investigated by scanning electron microscopy in order to characterize the dominant wear<br />
mechanisms. The coating wear rate was negligible up to 200°C exhibiting a decreasing tendency;<br />
however, the wear dramatically increased at higher temperatures. The coating peeled off after the test<br />
at 600°C.<br />
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