Preparation and Tribological Properties of Self-Lubricating Composite Wear-Resistant Structure on Titanium Alloy Surface

With the development of aerospace equipment, titanium alloy is more and more used in aerospace equipment components because of its many advantages. At the same time, the poor tribological properties of titanium alloy limit its further application in the field of tribology. In this study, the micro-structures with different morphologies and texture densities were prepared on the surface of TC4 titanium alloy by laser micromachining. The self-lubricating composite wear-resisting structures were prepared by combining surface texture, thermal oxidation film and PTFE lubrication film on the TC4 surface. The effects of texture morphology and texture density on the friction and wear properties of the composite structure under sliding condition were investigated, and the friction-reducing and anti-wear mechanism between PTFE lubrication film and micro-texture of titanium alloy surface was analyzed. The impact of introducing of thermal oxidation film on wear life was further studied. The results showed that the lubricating film on the untextured surface of the titanium alloy had a high and fluctuating friction coefficient, showing severe wear. However, the adhesion force of film on the textured surface increased significantly. Compared with the lubricating film of untextured surface, the combination of textured surface and lubricating film can significantly enhance the friction reduction and wear resistance of the material. With the increase of texture density, the friction coefficient and wear rate were further reduced. Under the optimal texture density, the lowest friction coefficient reached 0.11, and the wear rate of the textured titanium alloy with the film was 1.5×10⁻⁶ mm³/(N·m), which was 99.3% lower than the wear rate of the untextured lubricating film. On the other hand, the combination of thermal oxidized textured surface and lubricating film further improved the wear resistance of material surface. The friction coefficient of the composite structure was as low as 0.12, and the wear rate of the lubricating film with thermal oxidized textured surface was as low as 0.8×10⁻⁶ mm³/(N·m), which was 46.1% lower than the wear rate of the lubricating film on non-oxidized textured surface. The linear thermal oxidized textured surfaces exhibited low and stable friction coefficient and extremely low wear rate at the same texture spacing comparing the circular thermal oxidized textured surfaces. It can be considered that the effective supplement of high density texture to lubricating medium and the wear resistance of high hardness thermal oxidation film played a synergistic role in reducing friction and anti-wear.