The effects of oil additives and mating materials to the friction, wear and seizure characteristics of a-C: H coating

In this study, friction and wear behaviour of amorphous hydrogenated carbon (a-C:H) DLC coating slide against SUJ2, TiC and TiN mating material disks in Base and ZnDTP+MoDTC oils boundary lubrication is comparatively investigated to determine the most favourable DLC/mating material/lubricant and interrelated tribofilm formation mechanism on each mating mating materials. Tribological tests were executed by utilizing roller on disk friction tester, nano-indentation hardness test, 3D optical surface profiler, and EDS-SEM were used to characterize the tribofilm formed on both worn roller and disk surfaces. The results showed that the wear volume of a-C:H/TiC tribo-pair in ZnDTP+MoDTC marked a tremendous wear volume reduction compared to than that of in Base oil. EDS investigation on tribofilm element investigation revealed that SUJ2 and TiN mating material disk attracted high concentration of Molybdenum at% on its surface that later caused high wear volume on both roller and disk sliding surfaces. TiC mating material disk however, formed a low at% yet helpful tribofilm consisting of a fraction of Zn phosphate from ZnDTP attached on both roller and disk which assisted the reduction of wear volume