Status and entrance mechanism of calcium and phosphate in microarc oxidation layer on titanium

A porous TiO₂ ceramic layer containing calcium and phosphate was prepared by microarc oxidation on titanium. The microstructure, compositions and elements of the ceramic layer were analyzed by SEM, XRD, IR and XPS. The results show that anatase and rutile are the main composition of the layer. With the increasing of applied voltage and Ca²⁺ concentration of electrolyte, the content of rutile increases. Under high voltage calcium comes into the layer and forms CaTiO₃, while phosphate comes into the layer and exists as PO₄^3-. They are homogeneously distributed on the ceramic layer. Diffusion and electrophoresis are the entrance mechanism for calcium and phosphate.