Production and Characterization of a Bone-Like Porous Ti/Ti-Hydroxyapatite Functionally Graded Material

A new kind of functionally graded material (FGM) that mimics the inner porous structure and outer dense layer of human bone was produced using powder metallurgy. The inner part of the FGM material (16 mm in diameter) has porosity of approximately 60%, and its mechanical properties are compatible with cortical bone; however, the shell (1.8 mm in thickness) is composed of a layer of Ti-10% wt. hydroxyapatite (HA) and shows hydrophilic behavior and improved biofunction. Elastic moduli of the core and shell layer were calculated as 18.99 and 42.98 GPa, respectively, and those values are compatible with that of cortical bone. Addition of HA to the shell had a significant effect on the wettability (81.6% decrease) and cell viability (46% increase). Furthermore, the porosity of the shell layer (28.88%) is similar to that of human cortical bone. It is concluded that the developed Ti-HA FGM has promising properties for implant applications.