Structure optimization and properties of hydroxyapatite-Ti symmetrical functionally graded biomaterial

The hydroxyapatite(HA)-Ti/Ti/HA-Ti symmetrical functionally graded biomaterial (FGM) combining the excellent biocompatible properties of hydroxyapatite ceramic and the good mechanical properties of titanium component is a very promising biomaterial for hard tissue replacement implant. The optimized distribution function of components of this FGM has been obtained based on the classical lamination theory and thermo-elastic mechanics to overcome the tendency toward microcracking in earlier samples firstly. The perfect FGM sample without any microcracks on the surfaces was fabricated by hot pressing successfully whose actual distributions of compositions and thermal residual stress have been analyzed by electron probe microanalyser (EPMA) and X-ray diffraction method, which are consistent with those designed theoretically. Its integral apparent bending strength can reach to 158.9 MPa, which is higher than that of human bone. HA-Ti/Ti/Ti-HA symmetrical FGM behaved integral-fracture without falling apart or delaminating under two different loading modes. As a result, the pure titanium layer could provide an effective support of mechanical properties for the whole functionally graded biomaterial. (C) 2001 Elsevier Science B.V. All rights reserved.