Ultrahigh tribocorrosion resistance of hydrogenated amorphous carbon coating via trace gradient W incorporation

In this work, we manipulated the trace gradient W incorporation combined with a increment top-layer thickness for the hydrogenated amorphous carbon (a-C:H) coating on thermally sprayed WC-based cermet. The tribocorrosion resistance of the modified a-C:H coating was investigated in terms of structural evolution during friction under 3.5 wt% NaCl solution. Regardless of introduction of gradient W doping, although the a-C:H coating maintained the sp²/sp³ atomic bond structure, the stress reduction and plasticity increase were obtained for coatings. Moreover, the stable open-circuit potential revealed that the tribocorrosion resistance of modified coating was significantly improved, as identified by the quite low wear rate and coefficient of friction at 1.46×10⁻⁸ mm³/N·m and COF of 0.067, respectively. Different with the traditional failure of worn-out and pitting corrosion of a-C:H coating in chloride solution, the designed robust interfaces and the functional top-layer enabled the coating to withstand longest sliding distance over 2100 m at heavy contacting pressure of 1.67 GPa. These observations offer the promising strategy to fabricate advanced carbon-based coatings with required extremely strong wear resistance and anticorrosion capability for mechanical components used in harsh marine environment.