Preparation And Characterization Of Zn-containing HA/TiO₂ Composite Coatings On The Surface Of Titanium

Titanium (Ti) and its alloys have been widely used in bioimplant applications because of their good biostability, superior mechanical strength and corrosion resistance. However, the implants of pure titanium or its alloys are poor in biological activity, and cannot form firm chemical bond with bone, which seriously affected the clinical success rate of titanium dental implants, and restricted the widespread launch of implantation. Therefore, preparation of bioactive coatings on Ti becomes to be focus in recent years.In this paper, TiO2 film was prepared on the surface of Ti by micro-arc oxidation (MAO) in order to get the influences of oxidation time on the aperture size, coating thickness and coating structure, etc. Then the sol-gel was applied on the TiO2 coatings for the preparation of HA coating with Zn2+ in order to increase the bioactivity. It has also been investigated that the influences of Zn on the HA crystal and the impact of ZnHA/TiO2 composite coatings on the growing of MG-63 osteoblasts.The result shows that, the thickness of TiO2 coating and the average aperture size on the coating surface increase with the extension of the MAO time. The infiltration and surface energy of the coating enhance with the increasing of the oxidation time, too. When the MAO time increases to 15min, HA/TiO2 is formed on Ti, but the coating then is too thick and uneven, the apertures on the surface are irregular, and the HA is not attached to the material surface evenly. TiO2 coating treated for 3min by MAO is more suitable for ZnHA/TiO2 as the transition layer, its anchoring strength with the substrate is larger than 57.3MPa.HA/TiO2 and ZnHA/TiO2 coatings on the pure Ti can be prepared by MAO and sol-gel, and the content of Zn2+ in the composite coatings can be controlled. After Zn2+ added to sol, the HA structure crystal will become weak and appear impurity. When n(Zn):n(Ca) changes between 0.005 to 0.05, the content of Zn will not change the HA structure crystal; when n(Zn):n(Ca) reaches 0.5, the crystallization of HA will almost completely destroyed. Compared to HA/TiO2 coatings, the existence of Zn2+ in ZnHA/TiO2 could promote the osteoblast adhesion and cytoskeleton formation.