Effect of mating materials on wear properties of amorphous hydrogenated carbon (a-C:H) coating and tetrahedral amorphous carbon (ta-C) coating in base oil boundary lubrication condition

Abstract

In this study, wear behavior of amorphous hydrogenated carbon (a-C:H) coating and tetrahedral amorphous carbon (ta-C) coating when sliding against various mating materials in base oil boundary lubrication condition is comparatively investigated to find out the optimal combinations of DLC/mating material and corresponding wear mechanism of both DLC coating. Tribological tests were performed in a cylinder-on-disc tribometer, Field Emission Scanning Electron Microscopy, Raman spectroscopy is used for characterization of ta-C and a-C:H worn surface. The results show that the specific wear rate of ta-C coating increases along with the hardness and roughness of mating material increases, while the specific wear rate of a-C:H coating increases together with an increment in the ID/IG ratio. It is concluded that for ta-C coating, local stress concentration-induced microfracture is the main wear mechanism in relative high wear scenario, along with minor graphitization-induced wear which prevails in low wear scenario. On the other hand, a-C:H coating showed that simultaneous generation and removal of the graphitized layer on the contact surface is the predominant wear mechanism.

Keywords

• DLC
• Wear resistance
• Boundary lubrication
• Mating material