| The mechanism of calcium and phosphorous entering ceramic coatings in the course of Miro-arc oxidation (MAO) was studied by the analysis of the effects of electric parameters on Calcium, Phosphorous component and their distribution in MAO coatings. The biological performance of MAO coatings was investigated by the hydrothermal synthesis test, the SBF test and the cell culture test.Results show that calcium and phosphorous comparative content increases with voltage or current density increasing, but calcium increases more quickly than phosphorous, and the atom ratio of Ca and P increases with the increasing of voltage or current density. The effects of duty cycle on calcium and phosphorous component are similar to the frequencies'. With duty cycle or frequency increasing, phosphorous comparative content decrease appreciably, while calcium comparative content and atom ratio of Ca and P increase. Diffusion and electromigration are respectively the primary mechanism of Ca and P entering the coatings in the course of MAO. From surface to inner, calcium content decreases gradually and phosphorous content remains generally uniform in the coating but decreases quickly to zero in the coating-substrate interface. The hydrothermal synthesis test indicates that a great deal of bioactive matter named hydroxyapatile was synthesized on the surface of MAO coatings after hydrothermal treatment. The SBF test indicates that the samples of atom ratio in lowor high Ca & P can induce much apatite formation in SBF for their excellent bioactivity, the meanwhile, the samples that of in middle can only induce few apatite formation for its less bioactivity. The cell culture discovers that osteoblasts can grow well on the surface of coating with higher atom ratio of Ca & P as well as roughness, which indicate that the coating has an excellent biological performance. |
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