Microstructure and property evolution of Cr-DLC films with different Cr content deposited by a hybrid beam technique

Cr-containing diamond-like carbon (Cr-DLC) films was deposited on silicon wafers by a hybrid beams system, which consists of a DC magnetron sputtering and a linear ion source. The chromium content in the films was adjusted by varying the fraction of Ar in the Ar and CH4 gas mixture. The composition, microstructure, surface morphology, mechanical properties and tribological behavior of the films were investigated by XPS, TEM, AFM, SEM, nano-indentation and tribological tester as a function of Cr content. It is shown that, as the Cr content increased from 1.49 to 40.11 at.%, the Cr-DLC films transfer from amorphous DLC with dispersed metallic-like Cr to composite DLC with carbide phases embedding in the DLC matrix, and the film surface morphology also evolve from flat surface into rough surface with larger hillocks. The amorphous Cr-DLC films exhibit a low friction coefficient and wear rate as pure DLC, while the composite Cr-DLC films show a higher friction coefficient and wear rate, although they possess a relatively high hardness.

Research highlights
► The Cr-DLC films with various Cr contents were deposited by the hybrid beams hybrid beam source.
► The Cr-DLC films transfer from amorphous DLC with dispersed metallic-like Cr to composite DLC with carbide phases embedding in the DLC matrix, as the Cr content increased.
► The amorphous Cr-DLC films exhibit a low friction coefficient and wear rate as pure DLC, while the composite Cr-DLC films show a higher friction coefficient and wear rate.