Abstract: Microarc oxidation coatings were prepared on pure titanium substrates in a Na₂CO₃ and Na₂SiO₃ electrolytic solution by microarc oxidation with the pulse frequency of 500～8000Hz, the effects of pulse frequencies on growth kinetics, surface morphology and phase composition of the coatings were studied.
The result shows that the coating growth rate is dependent on the pulse
frequency. When the frequency is less than 2000Hz, with the increase of frequencies, the coating growth rate decreases sharply, while the frequency is greater than 4000Hz, it keeps almost invariable with the treating frequency increased. The coatings consist of plentiful rutile and anatase, and a small quantity of unsaturated oxideTiO_2-x, (0.022-x reduces gradually with the increase of the frequency. The coating surface is porous, with the frequency increasing, the roughness and micropore size of the coating surface decrease gradually, and the pore number increases little by little.

Key words: microarc oxidation, pulse frequency, surface morphology, phase component