Tribological evaluation of thermally activated CVD diamond-like carbon (DLC) coatings

Abstract

Diamond-like carbon coatings have been the subject of expanding technological interest for wear resistance and low friction applications during recent years. In this study, diamond-like carbon coatings were deposited by thermally activated chemical vapour deposition. The deposition temperature was 900°C and CH 2I 2 was used as a precursor. Tribological evaluation was performed by surface roughness measurement together with hardness, micro abrasion and friction. Furthermore, the residual stress of the coating was evaluated by a deflection method. The coating was analysed with nuclear reaction analysis, scanning electron microscopy and atomic force microscopy. The coating was very smooth ( R a = 1 nm) and free from pores. A high abrasive wear resistance slightly worse than physical-vapour-deposited TiN was measured. It exhibit a hardness of 2800 HV and a friction coefficient of about 0.2 in air (30–50% relative humididty). Furthermore, the coating has a compressive residual stress of 220 MPa. Hydrogen content and density of the coating were 9 at.% and 1.8 g cm −3, respectively.