Al-Doped Ga-Based Liquid Metal: Modification Strategy and Controllable High-Temperature Lubricity through Frictional Interface Regulation

Ga-based liquid metal (GLM) may be a potential heat-transfer material in many industries such as electronic devices and nuclear reactors, and thus, improving its lubricity is conducive to solving the friction and corrosion problems of the motion pairs served in the GLM medium. This paper proposes a modification strategy based on the conventional and large-scale mechanical milling to prepare Al-doped GLM successfully and regulates the GLM lubricity through controlling the frictional interface properties. It is found that at room temperature (∼20 °C), the Al element in the Al-doped GLM medium has a stronger adsorption capacity on the T91 surface, so the Al-rich film is formed on the frictional interfaces and reduces the wear of the T91 disk effectively compared to that in the GLM medium. However, the doping of Al is detrimental to the wear resistance of the T91 steel significantly at 400 °C by inhibiting the formation of the protective FeGa₃ film on the frictional interfaces, which readily appears at T91 frictional interfaces in the GLM medium. At 600 °C, Al atoms participate in the formation of a multilayer intermetallic film, thus improving the wear resistance again. This paper provides a new idea for preparing the metal-doped GLM and improving the lubricity of GLM, and it drives forward our understanding of the lubrication mechanisms of liquid lubricants.