Effect of NaAlO2 concentrations on the properties of micro-arc oxidation coatings on pure titanium

Abstract TiO2 coating was deposited on a pure titanium substrate using a micro-arc oxidation (MAO) process in an electrolyte solution with the NaAlO2 addition varying from 0 to 0. 4 g/l. With increasing NaAlO2 concentration, the working voltage could effectively increase and promoted the growth rate of MAO coatings on pure titanium. The X-ray diffraction (XRD) results indicated that MAO coatings mainly consisted of TiO2(B), rutile, and anatase. The surfaces of the MAO coatings which were formed on pure titanium in the electrolyte without NaAlO2 mainly consisted of micro-pores. The number of the sintered disc and the discharge channel diameter increased with increasing NaAlO2 concentration. The corrosion rates of MAO coatings decreased at the first and then increased.