TRIBOLOGICAL PROPERTIES AT 20 AND 500°C OF TiN AND CrN CATHODIC ARC COATINGS DEPOSITED ON Ti-6Al-4V ALLOY

Tribological properties of TiN and CrN coatings deposited by cathodic arc method at three different bias potentials -50, -150 and -300V on Ti-6Al-4V alloy in pair with alumina have been investigated. X-ray diffraction analysis showed that single-phase textured cubic nitrides of TiN and CrN were formed in these coatings. It is shown that the friction coefficient of the coatings is practically equal to that established for the Ti6Al4V alloy, but the wear rate is more than an order of magnitude lower than for the titanium alloy substrate. Coatings deposited at a potential of -50 V show optimal tribological properties at temperatures 20 and 500 degrees C. Friction coefficients for TiN coatings are 0.4-0.8 at 20 degrees C and 0,75 at 500 degrees C; for CrN coatings they are 0.5 at 20 degrees C and 0,7 at 500 degrees C. Wear rates for TiN coatings are 0.86<middle dot>10(-5) & mcy;& mcy;(3)/& Ncy;& mcy; at 20 degrees C and 3.56<middle dot>10(-5) & mcy;& mcy;(3)/& Ncy;& mcy; at 500 degrees C; for CrN coatings they are 1.43<middle dot>10(-5) & mcy;& mcy;(3)/& Ncy;& mcy; at 20 degrees C and 7.13<middle dot>10(-5) & mcy;& mcy;(3)/& Ncy;& mcy; at 500 degrees C.