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.

Keywords:

• DCPGD
• DLC
• Composition
• Microstructure

Acknowledgment

This work was supported by the National Natural Science Foundation of China (grant no. 11205050).