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.