Effect of structure of tetrahedral amorphous carbon (ta-C) coating on friction and wear properties under base-oil lubrication condition

Tribological properties of unique amorphous carbon (unique a-C) coating with mesh structure was investigated and compared with the standard ta-C and a-C:H under base-oil lubrication using roller-on-disk tribo-tester. The friction coefficient for unique a-C and the standard ta-C shows the same trend of decreasing over the load. While the a-C:H shows reduction in friction coefficient as the load increased. Moreover, the wear rate at 20 N loads was less than 2.0x10-9 mm3/Nm unique a-C as compared to 3.2x10-8 mm3/Nm for standard ta-C. It is a result of inhibition of brittle micro-fracture by the structure and abrasive particle hardness produced by the unique a-C which is three times softer than the standard ta-C. The aC:H coating wear mechanism explained by the contact surface structure transformation to graphite.