Toward low friction in high vacuum by designing textured a-C/IL duplex lubricating film

The advanced space technologies urge us to develop a superior lubricant that owns low friction coefficient and high anti-wear abilities in high vacuum environment. Herein, we designed a novel textured a-C/ionic liquid (IL) film and investigated its vacuum tribological performance. The worn surfaces of as-deposited film and corresponding counterpart ball were investigated in detail. The results showed that the combined effect of textured grooves and IL obviously improved tribological performance of a-C film in vacuum environment. The grooves acted as IL reservoirs that promoted retention of the lubricating film and prevented direct contact between the solid surfaces. In addition, these textured grooves also acted as buffers that trapped and collected wear debris, thereby preventing the break down of the tribological system. The characterization results confirmed the formation of IL containing carbon-based tribofilm between the rubbed surfaces under joint effect of textured patterns and IL lubrication.