Long-term thermal stability of Si-containing diamond-like carbon films prepared by plasma source ion implantation

•Long-term stability of silicon-containing diamond-like carbon films investigated•Annealing for 1 week at temperatures from 523 K to 773 K•Higher silicon contents suppress thermal degradation.•Hardness and friction coefficient nearly unchanged for temperatures up to 573 K.•Higher temperatures led to decreased hardness with friction coefficients still being low.

The long-term stability of silicon-containing diamond-like carbon films was investigated. The samples were prepared by plasma source ion implantation with a mixture of tetramethylsilane (TMS) and acetylene (C2H2) using negative high voltage pulses. The film composition was changed by varying the flow rates of the TMS and C2H2 gases, resulting in a Si content from 0 to 44 at.%. After deposition the films were annealed at temperatures from 523 K to 773 K for 168 h in ambient air. The effect of the Si content on the structure, the mechanical and tribological properties of the DLC films was investigated. A silicon oxide layer is produced on the surface of the film which improves the thermal stability. Mechanical and friction characteristics of the Si-DLC were not much affected by the long-term thermal annealing if the temperature was kept below 573 K.