ISSN 0862-5468 (Print), ISSN 1804-5847 (online) 

Ceramics-Silikáty 55, (4) 305 - 311 (2011)


TRIBOLOGICAL PROPERTIES OF TiBx AND WC/C COATINGS
 
Lofaj František 1,2, Mikula Marian 3,4, Grančič Branislav 4, Cempuras Gragorz 5, Horňák Peter 1, Kúš Peter 4, Kottfer Daniel 6
 
1 Institute of Materials Research of SAS, Watsonova 47, 040 01 Košice, Slovakia
2 Faculty of Materials Science and Technology in Trnava, Slovak University of Technology in Bratislava, Paulínska 16, 916 24 Trnava, Slovakia
3 Institute of Materials and Machine Mechanics of SAS, Račianska 75, 831 02 Bratislava, Slovakia
4 Faculty of Mathematics, Physics and Informatics, Comenius University in Bratislava, 842 48 Bratislava 4, Slovakia
5 Faculty of Metals Engineering and Industrial Computer Science, AGH University of Science and Technology, Al. A. Mickiewicza 30, PL-30059 Kraków, Poland
6 Faculty of Mechanical Engineering, Technical University of Košice, Mäsiarska 74, 040 01 Košice, Slovakia

Keywords: Coefficient of friction, Thin nanocomposite coatings, TiB₂, WC/C, Transfer film
 

Tribological properties of TiBx and WC/C coatings have been studied using the ball-on-disc method at room and elevated temperatures in air to investigate their behavior under conditions approaching high performance dry cutting. The average room temperature coefficients of friction (COF) of both nanocomposite DC magnetron sputtered TiBx coatings and PECVD WC/C coatings were in the range 0.2-0.6. The lowest value of TiBx coatings of 0.16 was achieved in case of prefferentially oriented stuctures deposited at the highest negative bias. The lowest COF of WC/C was around 0.11. The increase of testing temperature to 450°C caused the increase of COF up to approximately 0.7-0.8. The experiments at elevated temperatures suggest the existence of the oxide transfer film with higher COF than that of the sliding contact without the film. Although both coating systems have relatively high COF values at elevated temperatures, they exhibit elements of some adaptive behavior.


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