Lubrication Characteristics of Multifunctional Liquid-State Metal Materials under Different Sliding-Pairs

Room temperature liquid metals are a family of innovative and multifunctional materials that display many intriguing and unique physicochemical properties. However, tremendous effort is needed to be made to explore many unknown properties and application fields of the liquid metals. Therefore, this paper preliminarily investigated the lubrication characteristics of two nontoxic liquid metals such as eutectic Ga_75.5In_24.5 and Ga₆₅In₂₂Sn₁₃ under different sliding-pairs. The results indicate that Ga-based liquid metal had poor wettability on the surfaces of steel and ceramic. When a ceramic ball slid against an AISI 52100 steel disc, liquid metals displayed an outstanding lubrication role and an excellent loading-carrying capacity lubricant. For the self-mated AISI 52100 steel sliding-pairs, the friction-reduction effect of the liquid metal was limited but it decreased the wear rate of the sliding materials significantly. For ceramicceramic sliding-pairs, no or limit lubrication was found under liquid metals environment. The lubrication discrepancy of liquid metal might be mainly correlated to its tribo-chemical reaction on the frictional surfaces.