Implantation of hydroxyapatite granules into superplastic Ti alloy substrate with deposited Ti film

Abstract

It was attempted to implant hydroxyapatite granules into a superplastic Ti-4.5Al-3V-2Fe-2Mo-alloy substrate. In order to improve the biocompatibility of the Ti-alloy, a pure titanium film was initially coated on the alloy substrate by reactive direct current (DC) sputtering method. Hydroxyapatite granules with 32-38 μm in diameter were spread over the coated Ti-alloy substrate and then pressed to implant the granules in the substrate. Upon implanting the granules at the temperature of 750°C, many cracks on the coating film were observed centering around the implanted granules, and the HAp granules themselves were observed to be damaged, too. In the meanwhile, upon implanting the granules at the temperature of 800°C, a pure titanium coating film was observed to become thin partially at the shoulder of the side wall in the vicinity of HAp granules; however, the granules were implanted into the alloy smoothly without any crack at all on the coating film and any damage to the granules. The hydroxyapatite implanted Ti alloy is expected to be useful for biomaterials as artificial bones and dental roots.