Enhancement of tribological performance of hydrogenated amorphous carbon films via ion implantation

This article demonstrates that ion implantation is an effective surface-modification method for tailoring the tribological performance of hydrogenated amorphous carbon (a-C:H) thin films. Nanometer-thick a-C:H films were implanted with various ion species (Si, Ti, Hf, and W) at low and high doses and species-specific energies, and their sliding behavior against Al₂O₃-TiC counterfaces was systematically investigated. The results reveal that implantation conditions strongly affect atomic mixing, defect generation, and local structural rearrangements in the carbon matrix. Si implantation produced only marginal improvements in wear resistance, with abrasive wear remaining the dominant mechanism. In contrast, Ti, Hf, and W implantation led to substantial enhancements in tribological performance, with high-dose Ti implantation yielding the most pronounced benefits. Implantation induced a transition in the dominant wear mechanisms from micropitting and debris plowing to nano-asperity removal, attributed to an ion-modified intermixing layer, which suppresses plastic shearing and increases the wear resistance of the a-C:H films.