Synthesis and characterization of low-friction Al-DLC films with high hardness and low stress

Al-diamond-like carbon films were successfully deposited by the reactive magnetron sputtering of Al target (>99.9%) in the argon and methane gas mixture atmosphere under selected substrate negative bias with high pulse cycle duty (50%). The microstructure, mechanical and tribological properties of the as-prepared Al-diamond-like carbon films were investigated. Results showed that these films were dominated by the typical amorphous structure, and the internal stress of films dramatically decreased while the hardness remained a high level (approximate to 20GPa) with increasing substrate pulse negative bias. Especially, the Al-diamond-like carbon film fabricated at substrate bias of -500V displayed a longer wear life and lower friction coefficient due to both itself superior mechanical properties and the formation of continuous and compact graphitized transfer layer, making it a good candidate for solid lubricating film in engineering applications.