Ultra-wide temperature lubricating and wear resistant amorphous carbon films via Si and WC co-doping and cross-scale multilayer designing

To promote the ultra-wide temperature adaptability of a-C-based films, a novel idea of Si and WC co-doping combined with cross-scale multilayer design was proposed in this work. The proposed film (cmSiWCC) was alternately stacked by the submicron-scale co-doped WC/Si/a-C sublayers and the nanoscale multilayered nmSiWCC sublayers. Three cmSiWCC films featuring nmSiWCC sublayers with different Si contents and a monolayer WC/Si/a-C film were constructed for comparison. Their microstructures and mechanical properties, as well as the tribological behaviors against ZrO₂ at 25–600 ℃ were studied. The results showed that the WC/Si/a-C monolayer film underwent significant deterioration at temperatures above 400 ℃. While the cmS45 film exhibited the best adaptability to temperatures from 25 ℃ to 600 ℃ with low average friction coefficients（＜0.15）and wear rates (<8.54 ×10⁻⁶ mm³/Nm). Attributing to the Si and WC co-doping, the temperature-adaptive lubricating phases of rich-sp² C, rich-sp² C+Si-O-C and WO₃+rich-sp² C formed at 25–200 °C, 300–500 °C and 600 °C accounted for the ultra-wide temperature lubrication behavior of the cmS45 film. Furthermore, in addition to the outstanding lubrication performance, the excellent oxygen barrier effect brought by the numerous interfaces in the cross-scale multilayer structure was another indispensable factor for the ultra-wide temperature wear resistance of the cmS45 film.