Microstructure and mechanical properties evaluation of molybdenum disulfide-titania nanocomposite coatings grown by plasma electrolytic oxidation

•A one-step plasma electrolytic oxidation process grows the MoS2-TiO2 nanocomposite oxide coating on Ti-6Al-4V alloy.•The added MoS2 particles cause shorter delay time and lower breakdown voltage to activate the point plasma discharge.•The PEO grown coating exhibits good cohesive and adhesive property, low coefficient of friction and low wear rate with 4 g/L MoS2 additive in electrolyte under 50% duty cycle.

In this work, the molybdenum disulfide-titania (MoS2-TiO2) nanocomposite oxide coating on Ti-6Al-4V alloy was fabricated by plasma electrolytic oxidation (PEO) process. The MoS2 particles with concentrations of 4 g/L was added into the electrolyte and three duty cycle values, 20%, 35% and 50% at a fixed frequency of 1000 Hz were used. We found that shorter activation time and lower breakdown voltage for the PEO reaction was achieved due to the addition of 4 g/L MoS2 particles in the electrolyte. The oxygen rich, rutile and anatase nonstoichiometric TiO2 phases were produced for all oxide coatings. In this work, the one-step PEO grown coatings consisting of MoS2-TiO2 nanocomposite structure with good adhesion, low coefficient of friction and low wear rate were achieved due to the lubricious effect of the 4 g/L MoS2 particles in electrolyte under a duty cycle of 50%.