Tribological properties of laser surface textured and plasma electrolytic oxidation duplex-treated Ti6Al4V alloy deposited with MoS2 film

Laser surface-textured Ti6Al4V substrate was treated by plasma electrolytic oxidation to form an oxide coating followed by deposition of a solid lubricating MoS2 film. The tribological properties were evaluated using a ballon-disk tribometer under dry sliding conditions at the loads of 0.3-5 N and a constant velocity of 0.1 m/s. The results showed that the presence of a mixed surface pattern consisting of a combination of large dimple arrays (diameter 200 mu m) and small discharge channels (diameter 5-9 mu m) fabricated by the LST/PEO duplex treatment helped in reducing the wear rate of the LST/PEO coating by one order of magnitude in comparison to that of the PEO coating. PEO coatings prolonged the lubricating life of MoS2 film by providing a rough surface for good adhesion and a hard layer for load bearing. The LST/PEO/MoS2 coating was proved to sustain low friction coefficient for a longer period than the PEO/MoS2 coating due to the fact that solid lubricants stored in both the discharge channels and the textured micro-dimples can be driven to the contact region. (C) 2014 Elsevier B.V. All rights reserved.