The microstructure and tribological properties at elevated temperatures of tungsten silicon nitride films

- The tribological properties at elevated temperatures of W-Si-N film were systemically investigated.
- The combination of silicon into W2N film could improve the tribological properties at elevated temperatures.
- Lubricant WO3 tribo-film led μ to exhibit relatively low value at RT and > 400 °C.
- The decrease of WO3 and the absence of moisture attributed to the improvement of wear resistance of the film at 100-200 °C.

W-Si-N films with various Si contents were deposited using a reactive magnetron system, and the film with the highest hardness, the lowest average friction coefficient (μ) and wear rate at room temperature (RT) was chosen to study the tribological properties at elevated temperature. Tribological properties of the film were performed using un-lubricated sliding tests against an alumina counterpart. Elevating the testing temperature from RT to 100 °C induced an intense skin plastic deformation, as a result, the μ increased rapidly and the wear rate decreased significantly. As the testing temperature was in the range of 100-200 °C, the surface deformation strengthening was induced furtherly, μ was further increased and the wear rate could not be calculated due the adhesive wear debris on the wear track. From 200 to 600 °C, the main wear mechanism changed to oxidation wear and the a lot of WO3 tribo-film led to the decrease of μ. Wear rate increased gradually due to the accelerated oxidation of the film and the disappearance of surface deformation strengthening.