Tribological Properties of High Hardness ta-CNx Coatings Deposited by Filtered Arc Deposition with Block-on-Ring Tribotester

Low friction and high wear resistance are strongly needed desired in boundary lubrication condition for industrial usage. Carbon nitride (CNx) coating is one of the promising materials, but the hardness of conventional CNx coating was only 10 GPa of nanoindentation hardness. In order to coat high hardness ta-CNx, we developed a dynamic mixing deposition method combining the filtered arc deposition system and nitrogen ion beam source. Nitrogen content was controlled by the nitrogen partial pressure in the deposition. Nanoindentation result gave the hardness of ta-CNx from 75 to 70 GPa, under the nitrogen content from 5 to 8 at.%. In order to clarify the tribological performance of ta-CNx coatings under the boundary lubrication, block on ring friction test was carried out. As a result, this new ta-CNx showed much higher wear resistance compared to the former soft CNx and hard ta-C coatings under PAO lubrication for the block-on-ring tribotester.