Implantation of hydroxyapatite granules into superplastic titanium alloy for biomaterials

Hydroxyapatite granules (32–50 μm in diameter) were spread over a superplastic titanium alloy substrate and pressed to implant the granules in the substrate. The more the stress increases, the deeper the granules were buried. Under 17 MPa for 10 min at 750°C, the only tops of the granules, which were surrounded by the alloy, were exposed and they were firmly stuck in the substrate. The granules and the titanium alloy were closed, and a reactive layer was formed at the interface between both of them. The implantation process of granules is divided in the following two steps. (1) First, the granules are implanted in the depth which is corresponding to the diameter with small stress. (2) Second, the whole of specimen is composed, and titanium alloy moves to the upper parts of the granules. Therefore, this composite is expected to be applied to artificial bones, like artificial hip joints and dental roots, as new biomaterials.