Investigation on preparation and properties of thick DLC film in medium-frequency dual-magnetron sputtering

Chromium-doped DLC film of about 6 μm in thickness was deposited using a medium-frequency dual-magnetron sputtering. The basic condition was Cr and C target powers in a range of 2-5 kW and substrate bias voltage held at −100 V in unipolar mode. Surface morphology, microstructure, hardness, adhesion, and friction property were investigated for the DLC film to be used as protective coating in industrial applications such as cutting tools, forming dies, etc. The thick DLC film with graded and multilayered structure exhibited some advisable properties: Vickers hardness was 1560 kg/mm2 at 250 g; adhesion was 52 N (Lc), a majority of film maintained at the end stage of scratch test; friction coefficient was 0.09, maintained in a long sliding endurance.