Formation Mechanism of Micro-arc Oxidation Medical Coating on Titanium Alloy Surface

Medical coatings on titanium alloy surface were prepared by micro-arc oxidation (MAO). The morphology characteristics of coatings at different oxidation stages were observed by scanning electron microscopy(SEM). The micro-arc discharge characteristics and electrochemical reaction of the two electrods were studied. The equivalent circuit of electrolyte load was established and analyzed. The hydroxyl-apatite(HA) coating formation mechanism of MAO was proposed. The results showed that the voltage could affect the charge distribution on specimen surface directly. The charge accumulation was enhanced, and the diffusion and electrophoresis degree of Ca2+and PO43- increased in electrolyte, which accelerated the instant reaction for the substances in coating.