Abstract: Microarc oxidation (MAO) coatings on titanium alloy were prepared in an aqueous solution of Na₂CO₃ and Na₂SiO₃ at a high voltage with special asymmetrical AC output, and the effects of treatment parameters such as cathodic and anodic peek voltages as well as treatment time etc. on the phase component of the coatings were studied by means of XRD. The experimental results show that the films consist of dominant rutile as well as a little anatase phase and Ti₆O₁₁ (TiO_1.83) phase, and their contents are closely relative to treatment time and the peak values of anodic and cathodic voltages. When the anodic and cathodic voltages were kept at 320 V and 45 V for 30 min, respectively, the rutile content of the film is the highest and its content exceeds 80%.

Key words: microarc oxidation, titanium alloy, treatment voltage, phase component