FRICTION AND WEAR OF SLIDING COUPLES COATED WITH TIC, TIN OR TIB2

Friction and wear tests of self-mated couples coated with TiC, TiN or TiB2 were performed with the pin-and-disc system in air and vacuum. The friction coefficients of the couples coated with TiC and TiN are approximately 0.2 in air and 0.5 in vacuum. The couple coated with TiB2 reaches higher values, 0.65 in air and 0.75 in vacuum. The wear rates of the couples TiN-TiN and TiB2-TiB2 are approximately equal in air and in vacuum although the operating wear mechanisms differ. TiC-TiC exhibits a high wear rate in air and a low wear rate in vacuum. Scanning electron microscopy observations, Auger analysis and small-spot electron spectroscopy for chemical analysis reveal that polishing, tribo-oxidation and adhesion are the main wear mechanisms, depending on the type of the coating and on the test conditions. © 1990.