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.