Effect of Electric Field on the Lubricating Performance of Ga-Based Liquid Metal

Ga-based liquid metal (GLM) can be used as a current-carrying lubricant, due to its combination of excellent electrical conductivity and good lubricity. However, the influence of electric field parameters on the lubrication mechanism of GLM is still unclear. This paper attempts to investigate the influence of current magnitude, voltage magnitude, current direction, and load on the lubrication behaviors of GLM at atmosphere and room temperature (≈26 °C). It is found that the interface action mechanism induced by an electric field is mainly reflected in four aspects, namely, Joule heating effect, electric field force, electrochemical effect, and electromigration effect. These interfacial physical and chemical effects are governed by the current magnitude, voltage magnitude, current direction, and load, bringing about distinct frictional products and thereby influencing the lubrication behaviors. Briefly, FeGa₃ can only be formed when the current reaches 6 A and the load is above 40 N, and it has obvious friction-reducing properties, but increases the wear due to its low content. When the frictional product is just the Ga-rich film, the increase of oxidation degree is detrimental to the wear resistance.