Formation mechanism and surface characterization of ceramic composite coatings on pure titanium prepared by micro-arc oxidation in electrolytes containing nanoparticles

The aim of this work is to study how nanoparticles incorporate into the prepared ceramic composite coatings on titanium by micro-arc oxidation (M.A.O.) technique in electrolytes containing nanoparticles and modify the surface characteristics. In order to achieve this goal, SiC and SiO2 nanoparticles (as main and auxiliary particles, respectively) were added to aluminate based electrolytes and M.A.O. process was performed under constant voltage regime using a pulsed power supply. Finally, the effect of addition of nanoparticles on current-time responses, surface morphology, thickness, chemical and phase composition of coatings were investigated. The obtained results showed that addition of nanoparticles (7.5 g/l) to the electrolytes, had no effect on the current-time responses and coating thickness of samples. However it caused a reduction in the size of micro-pores and surface roughness of M.A.O. coatings. It was also concluded that nanoparticles incorporate into the coating with the aid of both electrophoretic force and micro-sparks.