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%.