The hydrothermal treated Zn-incorporated titania based microarc oxidation coating: Surface characteristics, apatite-inducing ability and antibacterial ability

To improve the bioactivity and antibacterial ability of Zn-incorporated microarc oxidation (MAO-Zn) coating, the MAO-Zn coating was modified by hydrothermal treatment with deionized water (MAO-Zn-HT-0) and 5 mol/L NH₃·H₂O solution (MAO-Zn-HT-5). The hydrothermal treatment had a significantly effect on the structure, element and phase compositions of MAO-Zn coating. The hydrothermal treated MAO-Zn coatings remained the rough porous structure. Meanwhile, there were some TiO₂ or CaTiO₃ particles formed on the MAO-Zn-HT-0 and MAO-Zn-HT-5 coatings. Moreover, due to the dissolution of Ca and P elements and the enrichment of Zn element, the content of Zn element on the hydrothermal treated MAO-Zn coating surface was greatly increased. In addition, the Zn element existed in the amorphous ZnO after hydrothermal treatment. The release behavior of Zn element in the hydrothermal treated MAO-Zn coating exhibited slow, stable and continued. Compared to MAO-Zn coating, the MAO-Zn-HT-5 coating showed excellent apatite-inducing ability due to the formation of CaTiO₃ and Ti-OH. Likewise, the antibacterial rates of the MAO-Zn-HT-0 coatings for E. coli and S. aureus were significantly improved due to the increase of Zn element on the MAO-Zn-HT-0 coating surfaces. Thus, the hydrothermal treatment was an effective method to improve the bioactivity and antibacterial ability of MAO-Zn coating.