Tribological properties of liquid-metal galinstan as novel additive in lithium grease

Gallium-based liquid metal (GBLM) was added into grease with different proportions and homogenized through mechanical agitation and ball milling. The tribological properties of pure GBLM, pure greases and GBLM as an additive in lithium greases have been investigated by four-ball test. Results showed that pure GBLM exhibited poor anti-wear performance under low load, and the lubricating performance of greases under high load was not satisfactory. After GBLM was added to the grease, the extreme pressure lubrication capacity of the latter was effectively increased, whereas the anti-wear performance under low load did not decrease. When the mass ratio of GBLM to specific commercial lithium grease reached 1:1, the weld load was over 10 kN, which was the maximum value for greases.