Formation of Porous Structure of the Metallic Materials Used on Bone Implants

Abstract

Research on improvement of structure and fabrication methods of the bone implants are carried out for many years. Research are aimed to shape the structures, that will have a Young's modulus value similar to the value of the human bones Young's modulus. Depending on the porosity, Young’s moduli can even be tailored to match the modulus of bone closer than solid metals can, thus reducing the problems associated with stress shielding of a human bones. The designed structure should also be characterized by a high abrasion and corrosion resistance to and allow bone ingrowth in the implant material to make the best bone-implant fixation. For this purpose, implants should have a porous structure with an appropriate pore size and with open-cell porosity. Material for bone implants must also have a high biocompatibility and bioactivity. Following these requirements, the metallic porous materials appear to be the most suitable material for bone implants. In this paper a various methods of a porous materials fabrication for bone implants are listed. It was shown that titanium and its alloys (e.g. Ti6Al4V or Ti13Nb13Zr) are widely used as biomaterials for implants. Research in order to increase their wear and corrosion resistance and to improve their biocompatibility and bioactivity are still carried out. One of the most effective methods of manufacturing the porous materials is a powder metallurgy (PM). In this paper the results of research under shaping the structure of the porous titanium alloy Ti13Nb13Zr are also presented. As a manufacturing method of the porous material from the investigated and mentioned above Ti alloy, the powder metallurgy (PM) was choosen - with and without the use of a space holders. Method of fabrication a spherical powder from the aforementioned Ti alloy and results of its morphology research are discussed. The applied powder compaction method (with use and without use of space holders) and the influence of a sintering process on the final microstructure morphology of porous material obtained from Ti13Nb13Zr alloy are also presented and discussed.