he surface modification of commercially pure tifanium (CP-Ti) by microarc oxidation (MAO) under different voltages was investigated using 1%H3P04 solution as an electrolyte. The microstructure, phase composition and elemental distribution of ceramic coatings were investigated using scanning electron microscopy (SEM) and X-ray diffraction. The corrosion behaviour of the coating was also examined by potentiodynamic polarisation testing in a 3-5 wt%NaCI solution. Micropore oxide films were formed on all the sample groups by MAO. The thickness and micropore size of the MAO coating increased with the increasing voltage. Energy dispersive X-ray spectroscopy results indicate that Ti, 0 and P became incorporated into the MAO coatings. At a low voltage of 250 V, the MAO coatings were composed of amorphous, P2O5, TÍP2O7 and titania phases (rutile and anatase). Variation of treatment voltages increased the ceramic coatings from an amorphous structure to a phase structure, and the P2O5 phase disappeared. The corrosion potential Ocorr of the MAO sample shifted towards nobler directions, and the corrosion density /corr fell significantly compared with that of the bare OP-Ti. Corrosion testing showed that the sizes of the micropore of the MAO samples obviously decrease, and the MAO surface becomes smooth.

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