High-Temperature Friction and Wear Behavior of Varying-C VN Films

Due to the enhanced self-lubricating ability at high temperature, VN-based film is identified as a good alternative to the relatively common counterparts. In this work, the high-temperature (300 degrees C and 600 degrees C) tribological behavior of varying-C VN films was studied in detail. The results showed that at 300 degrees C or 600 degrees C, the friction coefficients of all these varying-C VN films are basically the same, and the wear rates have a rough downtrend from VN film to VCN-40 film. For each of these varying-C VN films, the friction coefficient decreases while the wear rate increases gradually with the increase in wear temperature, owing to the different composition of the tribo-chemical product (V-oxides) and the fact that the friction resistance of VO2 is not as good as that of V2O5, while the wear resistance of VO2 is superior to that of V2O5. However, the wear mechanisms of varying-C VN films, at 300 degrees C and 600 degrees C , are all principally oxidation wear. Besides, the orthorhombic diamond phase is oxidized during high-temperature friction and wear, leading to the loss of the anti-friction characteristics, and the coupling effect of high temperature and tangential friction force may result in the abnormal transformation of sp(2) C-C to sp(3) C-C, which contributes to the improvement of wear resistance to some extent.

Automated summary

The study found that VN films with different carbon contents exhibit similar friction properties at high temperatures, with wear rates increasing with temperature. Friction coefficients decrease while wear rates increase as wear temperature rises. Oxidation wear is the primary wear mechanism for VN films at high temperatures.