Effect of textured DLC coatings on tribological properties of titanium alloy under grease lubrication

Abstract To improve the tribological properties of titanium alloy surface and promote the functional application of titanium alloy, the synergistic anti-friction and wear-resistant effect of laser micro-textures and diamond-like carbon (DLC) coatings on titanium alloy surface under grease lubrication were investigated in this paper. Micro-textures and DLC coatings were fabricated on the surface of titanium alloy by Nd:YAG laser and magnetron sputtering technology. Effects of different surface treatment methods and micro-textures parameters on tribological properties of titanium alloy samples was studied. The results showed that, compared with the smooth titanium alloy sample, the friction coefficient of micro-textured sample, DLC coated sample and textured DLC coated sample decreased by 43.7%, 75.8%, 80.6% respectively. The surface of textured coated titanium alloy had the best tribological properties with a friction coefficient of 0.0799. The wear on the surface of the titanium alloy sample treated by laser micro-textures and DLC coatings was obviously improved. Compared with the severe adhesive wear on the surface of the titanium alloy sample, the surface of the textured coated titanium alloy sample was slightly scratched, and the wear volume was decreased by 97.5%. Meanwhile, DLC coatings with 30% textures density and 20 μ m textures depth showed the best anti-friction effect as well as the optimal hydrodynamic lubrication effect. Under the condition of grease lubrication, the surface of textured DLC coated titanium alloy substrate presented favorable anti-friction and wear-resistance effects, which revealed that reasonable micro-textures density and depth could more effectively exert the lubricating and anti-friction properties of textured DLC coatings.