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

The hydroxyapatite(HA)-Ti/Ti/HA-Ti symmetrical functionally graded biomater ial (FGM) combining the excellent biocompatible properties of hydroxyapatit e ceramic and the good mechanical properties of titanium component is a ver y 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 th e tendency toward microcracking in earlier samples firstly. The perfect FGM sample without any microcracks on the surfaces was fabricated by hot press ing successfully whose actual distributions of compositions and thermal res idual stress have been analyzed by electron probe microanalyser (EPMA) and X-ray diffraction method, which are consistent with those designed theoreti cally. 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 effec tive support of mechanical properties for the whole functionally graded bio material. (C) 2001 Elsevier Science B.V. All rights reserved.