Oxidation-regulated wide-temperature tribological behavior and mechanism of a Mo/Mo tribopair lubricated by Ga-based liquid metal

Gallium-based liquid metals combine fluidity with high thermal and electrical conductivity, making them attractive for lubrication in demanding environments. We investigated the tribological behavior of a Mo/Mo self-mated pair lubricated with Ga-In-Sn (GIS) from room temperature to 300°C in air and argon. Friction and wear tests, together with energy-dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) analyses, were used to examine interfacial behavior and tribofilm formation. In air, GIS reduced the Mo-disk wear rate by 90.9%–99.4% compared with the unlubricated pair, accompanied by the formation of a Ga-O-rich tribofilm. In argon, localized Ga retention, tribofilm delamination, and lamellar spalling became more pronounced at elevated temperature, leading to a wear rate of 15.6 × 10 −5 mm 3 /(N·m) at 300°C. These results provide insights into the effects of environmental conditions on liquid-metal lubrication and support the selection of suitable lubrication conditions for high-temperature sliding systems.