Oxide-based tribofilms and tribological behavior of self-mated Ti3SiC2 lubricated by PbO powders at high temperatures in nitrogen flow

•Lubricated by PbO powders, both the friction and wear of Ti3SiC2 decrease greatly.•During sliding, tribofilms containing Pb are formed on the tribo-interface.•The happening temperatures are different for tribochemical and thermal reactions.•Happening at the same temperature, products are different for the two reactions.

The friction and wear of self-mated Ti3SiC2 under unlubricated condition and lubrication of PbO powders from room temperature to 700 °C in a nitrogen flow are studied. The results show that compared to unlubricated condition, the friction coefficient of self-mated Ti3SiC2 under lubrication of PbO powders decreases from 0.9 to 0.3–0.5 and the wear rates for pin decreases from 10−2–10−3 to 10−5–10−7 mm3/N m. The SEM and Raman results indicate the microstructure and chemical composition of tribofilm at high temperatures have a strong effect on the friction and wear of self-mated Ti3SiC2 under lubrication of PbO powders. The composition of tribofilm varies with tribochemical and thermal reactions happening between PbO and SiO2/TiO2 on the tribosurface. The composition of tribofilms are analyzed to be PbO at room temperature, PbO and Pb3O4 at 400 °C, and PbTiO3 and PbSiO3 at 700 °C. The PbSiO3 is formed by tribochemical reaction while it cannot be formed under thermal condition.