Effect of micro/nano-textures and burnished MoS2 addition on the tribological properties of PVD TiAlN coatings against AISI 316 stainless steel

To improve the tribological properties of TiAlN coated surfaces, the effects of laser surface texturing (LST) and burnished MoS2 addition were investigated. Two types of surface textures were fabricated prior to TiAlN coating deposition: (i) nano-scale textures fabricated by femtosecond laser, and (ii) micro-scale textures fabricated by Nd:YAG laser. MoS2 powder was applied to conventional and micro-scale textured TiAlN coated surfaces. Thus, four different samples were fabricated: 1. TiAlN coated sample (CS), 2. nano-scale textured TiAlN coated sample (NCS), 3. TiAlN coated sample burnished with MoS2 (CS-M), and 4. micro-scale textured TiAlN coated sample burnished with MoS2 (MCS-M). The tribological properties were evaluated using a ball-on-disk tribometer at a load of 10-40 N and velocity of 2-10 mm/s. The results show that MoS2 addition and nano- or micro-scale grooves improve the tribological performance of TiAlN coatings. Nano-scale textures remarkably increase the wear life of TiAlN coatings, while it has no significant effect on the coefficient of friction (COF). MoS2 addition remarkably decreases the COF values, and micro-scale textures improve the effective life of the initial MoS2 layer for a longer period than the untextured one. The possible mechanisms for the effects of surface texture and burnished MoS2 are discussed.