Thermal stability and tribological properties of Si-incorporated DLC films

Thermal stability and tribological properties of Si-incorporated diamond-like carbon (Si-DLC) films were investigated. The DLC films were deposited by a bipolar-type plasma based ion implantation and deposition (PBII&D) technique, and the Si contents in the films were varied from 0 to 29 at.%. The deposited DLC films were annealed at 500 degrees C in ambient air. The changes of the structure and mechanical properties of the Si-DLC films with a high Si content (>= 21 at.%) by the thermal annealing were minimal. The 21 at.% Si-DLC film annealed at 500 degrees C shows low wear as well as low friction, whereas the 29 at.% Si-DLC film exhibited a high friction due to the creation of cracks on the worn surface related to the SiC-like nature. The 11 at.% Si-DLC film annealed at 500 degrees C shows the lowest friction coefficient at the cost of the significant wear in the graphitized film. The formation of a thick silicon oxide layer on the Si-DLC film could be favorable for low friction and wear.