A type of TiO2-based bioactive ceramic coatings containing Ca and P with the capability of inducing hydroxyapatite (HA) was obtained on the surface of pure titanium samples by plasma electrolytic oxidation(PEO)-alkali and heat (PEOAH) treatment. The morphologies, elemental compositions and phase components of the coatings at different stages were characterized by SEM, EDX and XRD. The results show that TiO2-based ceramic coatings were obtained on pure titanium by PEO within an electrolyte containing calcium salt and phosphate. Alkali and heat treatment helped calcium titanate and calcium phosphate form in the coatings. Having been immersed in simulated body fluid for 7 days, the PEOAH samples lost their original porous structures. Instead, the coatings were completely covered with a dense layer of spherical apatite. After 14 days' immersion, the apatite layer became denser and stick-shaped apatite crystals with higher crystallinity began to form. The apatite layers are composed of mesh structures, and the diameters of the mesh pores are less than 100 nm.

Keywords: Titanium, Plasma electrolyte oxidation (PEO), Alkali and heat treatment, Hydroxyapatite (HA).