Preparation of MoS2 Thin Films on Textured Surfaces of Titanium Alloy and Study of Fretting Tribological Performance

Titanium alloy, with its exceptional mechanical properties and low density, has been extensively utilized in aerospace and other industries. However, the relatively poor wear resistance of titanium alloy has been a primary factor limiting its application in the field of tribology. Therefore, improving the tribological performance of titanium alloys, particularly by enhancing their surface properties through surface engineering techniques, is of significant research value. This study presented a method for improving the fretting wear properties of titanium alloys by combining surface texturing and solid lubrication films, providing both methods and theoretical support for such enhancements. In the experimental procedure, an ultraviolet laser micromachining system was used to create pit-like textures on the surface of Ti-6Al-4V (TC4) alloy samples with diameters of 50 μm and densities of 10%, 20%, and 30%. A rubbing method was employed to prepare composite lubrication structures on the textured titanium alloy surfaces. The tribological properties of these composite lubrication structures were evaluated using the SRV-IV fretting wear tester, and wear marks were analyzed by using SEM. The study revealed that when the counterpart sphere was GCr15, the combination of surface texturing and solid lubricants significantly reduced material wear and extended lubrication life. The composite lubrication structure effectively lowered the friction coefficient, maintaining a low-friction state over an extended period. Under high loads, the sample containing MoS2 film with a texture density of 20% exhibited the best tribological performance, with MoS2 transfer films forming on both the textured and counterpart surfaces, resulting in the longest lubrication life. In low-density samples (10%), the transferred MoS2 was insufficient to form a lubricating film on the sample surface, while excessively high densities (30%) led to increased surface roughness and a corresponding rise in force of friction. When the counterpart sphere was TC4, under the same test conditions, the wear resistance life of the composite lubrication structure was significantly lower than that observed with GCr15 spheres. The composite lubrication structure lost its effect during initial operation, and surface texturing could not effectively reduce the friction coefficient or extend the solid lubrication film's lifespan. SEM observations revealed that the textured pits were filled, and no transfer film was formed on either the sample or counterpart surfaces. In conclusion, both texture density and counterpart materials had a significant impact on the fretting wear performance of composite structures. Appropriate texture density can notably extend the fretting wear life of composite lubrication structures. The pits formed by surface texturing can accommodate MoS2, and the wear debris generated by fretting wear could also extrude MoS2, supplementing the consumption of solid lubricants on the surface, ultimately achieving the reduction of wear and friction. © 2024 Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences. All rights reserved.