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

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 sub strate by reactive direct current (DC) sputtering method. Hydroxyapatite gr anules with 32-38 mum in diameter were spread over the coated Ti-alloy subs trate and then pressed to implant the granules in the substrate. Upon impla nting the granules at the temperature of 750 degreesC, many cracks on the c oating film were observed centering around the implanted grannies, and the HAp granules themselves were observed to be damaged, too. In the meanwhile, upon implanting the grannies at the temperature of 800 degreesC, a pure ti tanium coating film was observed to become thin partially at the shoulder o f the side wall in the vicinity of HAp granules; however, the grannies were implanted into the alloy smoothly without any crack: at all on the coating film and any damage to the grannies. The hydroxyapatite implanted Ti alloy is expected to be useful for biomaterials as artificial bones and dental r oots.