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

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%.