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Study of protective diamond-like carbon films on GCr15 bearing steel

Abstract Hydrogenated diamond-like carbon (H-DLC) were deposited on GCr15 bearing steel by double cathodes pulse glow discharge (DCPGD) plasma vapour deposition at different gas volume ratios. The surface morphology, composition, microstructure, hardness and friction properties of the H-DLC films were observed. It was found that the sp3 bond content and I(D)/I(G) ratio of DLC films were between 58 and 61% and in the range of 0·68–0·88, respectively. When H2∶Ar∶C2H2 gas volume ratio ranges from 4∶1∶1 to 8∶1∶1, the I(D)/I(G) ratio decreases with an increase in the sp3 bond content, the friction coefficient (about 0·1) and wear rate (between 4·5×10−8 and 8·4×10−8 mm3 N−1 m−1) of DLC films were very low. In this study, when H2∶Ar∶C2H2 gas volume ratio is 6∶1∶1, the thickness of the film is 8·13 μm deposited for is 4 h, the hardness reaches a maximum value (22·5 GPa), the friction coefficient and wear rate reduce to a minimum value, 0·094 and 4·5×10−8 mm3 N−1 m−1, respectively.