Titanium structures with porosity gradient - space holder manufacturing and characterization

ABSTRACT It has proposed the use of porous titanium to reduce the problem of mechanical incompatibility, which occurs between such material used in implants and bone. The pores introduction in titanium decreases its elastic modulus by bringing it closer to that of both cortical and trabecular bones. This paper describes titanium fabrication by powder metallurgy with longitudinal porosity gradient, using as space holder material, ammonium hydrogen carbonate, in different proportions, mixed with titanium hydride powder. After layered uniaxial compaction and subsequent sintering at 1150 °C, cylinders with gradual longitudinal porosity 2 % - 30 %, 2 % - 60 %, 30 % - 60 % and 2 % - 30 % - 60 % were obtained. Microstructure, size, shape and pore distribution, elasticity modulus and yield stress were analyzed in the samples. The results indicate that by the method studied, it is possible to obtain sinterized samples with porosity gradient, structural continuity between the different porous layers, with a range of pore size between 200 and 250 µm. The elasticity modulus in samples was similar to those reported in the literature for cortical bones and is compatible with the bone tissue anisotropic structure.