Comparisons of tribological property of a-C, a-CNx and BCN coatings sliding against SiC balls in water

Amorphous carbon-based coatings such as a-C, a-CNx and BCN coatings were deposited on SiC disks using ion beam assisted deposition (IBAD). The friction and wear property of these three carbon-based coatings against SiC balls were evaluated using a ball-on-disk tribo-meter in distilled water. The lowest mean steady-state friction coefficient of 0.015 was obtained for the a-CNx/SiC tribo-pair, while the largest mean steady-state friction coefficient of 0.09 was obtained for the a-BCN/SiC tribo-pair. Furthermore, BCN coating and SiC ball in a-BCN/SiC tribo-pair exhibited the largest specific wear rates, whereas the SiC ball had the lowest wear rate as sliding against a-CNx coatings. This indicated that the alloy elements such as N and B have different influences on the stability of the coatings in water, and thus affected the tribological property of carbon-based coatings in water.