The effect of chemical treatment on apatite-forming ability of the macroporous zirconia films formed by micro-arc oxidation

Macroporous and nano-crystalline zirconia film was prepared by micro-arc oxidation (MAO) of zirconium, and the effect of chemical treatment in H2SO4 or NaOH aqueous solutions on the microstructure and apatite-forming ability of the film was investigated. Compared with the MAO film, the chemically treated films do not exhibit apparent changes in phase component, morphology and grain size, however, have more abundant basic Zr-OH groups. The films treated with H2SO4 and NaOH solutions can induce apatite formation on their surfaces in simulated body fluids (SBF) within 1 day, whereas no apatite was detected on the untreated ZrO2 surface by 30 days. It is believed that the enhanced apatite-forming ability of the chemically treated ZrO2 films is related to the abundant basic Zr-OH groups on their surface.