Effect of a micro-textured surface with deposited MoS2-Ti film on long-term wear performance in vacuum

To improve the long-term tribological properties of precision moving parts in aerospace, MoS2-Ti film was applied on a low-density micro-textured surface of the most commonly used 9Cr18 steel. The 1.0, 1.5, 2.0 and 3.0 % dimple densities of micro-textured surfaces were produced by an Nd: YAG femtosecond pulse laser system. The effects of different micro-textured densities surface with MoS2-Ti films on friction properties and wear mechanisms were investigated. Tribological results showed that all the micro-textured surfaces with MoS2-Ti films had a lower friction coefficient and wear rate than the un-textured surfaces with MoS2-Ti films. The wear performance was enhanced by increasing the density of the micro-textured surface. The friction coefficient and wear rate after 3.6 × 105 lap rotation were reduced to below 0.018 and <1.0 × 10−7 mm2/N•m, respectively, when the density of micro-texture was 3.0 %. It was found that the friction coefficient and wear rate increased with increasing sliding laps, but the 3.0 % density surface with MoS2-Ti film after a lap rotation of 9.0 × 105 still had a lower wear rate than the un-textured surface, indicating an excellent long-term wear resistance. The function of micro-textures is not only to capture wear debris and store lubrication films but also to form a moderate transfer layer on the friction pair, all of which could help to prolong the wear life of MoS2-Ti films.