EFFECT OF SUBLAYER ON THE STRUCTURES AND TRIBOLOGICAL PROPERTIES OF GLC COATING ON Al-BASED ALLOY

Graphite-like carbon (GLC) film is a kind of antifriction coating. Cr/Cr-C/GLC and Al/Al-Cr-C/GLC composite coatings were prepared by using an unbalanced magnetron sputtering system on Al-based alloy, where Al and Cr layer are the sublayers, Cr-C and Al-Cr-C are the transition layers. As a comparation, the GLC coating without sublayer was also deposited on the substrate. The microstructure, binding force and tribological properties of as-deposited coatings were studied. The results show that the Cr sublayer shows a columnar growth structure, while the columnar grain is not found in the Cr-C transition layer which has a gradient composition distribution. There is a good combining interface between Al sublayer and Al-based alloy substrate. Al-Cr-C transition layer has a gradient composition distribution also. GLC layers based on different sublayers and transition layers have amorphous structures. Compared with GLC coating without sublayer, the binding forces of Cr/Cr-C/GLC and Al/Al-Cr-C/GLC composite coatings are obviously higher, and the Al/Al-Cr-C/GLC composite coating has the maximum critical load. Under different loading conditions, the friction coefficients of both Cr/Cr-C/GLC and Al/Al-Cr-C/GLC composite coatings are low and similar to each other.