Effect of electrical parameters on characteristics of microarc oxidation coatings of commercially pure titanium in colloid

The effects of the pulse voltage amplitude (U) and duty cycle (d) on the growth characteristics, microstructure, phase component and corrosion resistance of the coating formed by microarc oxidation (MAO) on commercially pure titanium substrates in colloid have been systematically studied. The results show that, with the increase of U or d, the coating thickness increases almost linearly, the pore size and the roughness of the surface increases gradually, while the pore density decreases. The coatings almost entirely consist of dense layer, and they are completely composed of rutile TiO2 except the one formed at the duty cycle of 10% (U =450 V), which contains a small amount of anatase TiO2. The corrosion resistance test in sulfuric acid solution (30%) shows that the corrosion resistance of the samples is closely related to U and d, with the increase of U or d, the corrosion resistance of the samples increases gradually.