Sr, Mg and Zn-substituted hydroxyapatite coatings on Ti-6Al-7Nb alloy by atmospheric plasma spray using powders produced by sol-gel and ball milling

The hydroxyapatite coatings are very important in biomaterials engineering due to their high in-vivo bioactivity and biocompatibility. Biological apatite is calcium deficient or non-stoichiometric and have minor elements as carbonate, sodium, magnesium, among others, with an important role in the biological properties of the apatite.

The substitution of hydroxyapatite can be achieved during the powder preparation by solid-state physical methods as ball milling or by liquid methods as the sol-gel process. In addition, it is possible to improve the antibacterial properties by adding zinc, silver or copper substitution.

In this work a zinc, strontium and magnesium multi-substituted hydroxyapatite have been synthesized by ball milling and sol-gel process. A comparison of the crystallinity and the effect of a post-thermal treatment on the mechanical properties have been achieved. These powders were deposited onto Ti-6A-7Nb alloy by atmospheric plasma spray and the coating’s mechanical properties was compared. In addition, the biocompatibility and the antibacterial properties against S. aureus were studied.

The objective of this project is to improve the antibacterial and osteogenic properties of Ti-6Al-7Nb implants coated by multi-substituted hydroxyapatite. The synergistic effect of the simultaneous addition of Zn, Sr and Mg on the hydroxyapatite crystal structure was observed.