Comparison among the lubricated and unlubricated tribological behavior of coatings obtained by PEO on the Ti6Al4V alloy in alkaline solutions

Coatings were obtained in electrolytes with different phosphorus source by Plasma Electrolytic Oxidation (PEO). Anatase phase (TiO2) is the main crystalline phase and rutile phase is in a minor proportion in coatings. Electrolyte with metasilicate of sodium as additive generates micro-discharges of higher size and intensity during PEO process, increasing the amount of rutile in the coating. Coatings improve wear behavior of substrate. Under the lubricated condition in Simulated Body Fluid (SBF), the formation of an amorphous layer of apatite during lubricated wear test improves the performance of coatings, allowing to slide a higher distance (100 m of sliding distance) without a significant wear in the coating against the unlubricated condition (15 m).