Obtención de compuesto de titanio con gradiente de porosidad mediante técnica pulvimetalúrgica

Abstract

Within the study of biomaterials for implantological use titanium is among the most widely employed metals due to its excellent corrosion and mechanical resistance. In spite of the advances made, there are some issues remaining with the value of the elastic moduli of the titanium (110GPa) in comparison with the elastic moduli of the cortical bone (20-30 GPa) and the trabecular bone (1-5GPa). This difference is one of the main reasons a bone prosthesis fails once implanted, producing what is known as Stress shielding. One of the techniques employed to diminish the elastic moduli of titanium consists in incorporating pores to the material. This is done through powder metallurgy techniques, allowing the fabrications of porous composites, sintering a mix of powders of metallic hydrides and spacers that are eliminated during the heat treatment. Taking into account the structural characteristics of the bone, it makes sense to think on the possibility of fabricating a prosthesis with pore gradients. Another problem encountered when employing titanium, is its inability to promote the osteointegration. There are different techniques to tackle this problem, and one of them is to incorporate hydroxyapatite which has the problem that it decomposes in the presence of titanium when sintered at high temperatures. The current study shows the results obtained during the fabrication of samples of titanium with pore gradients. We studied different fabrication techniques, analyzing each stage during the powder metallurgy. process. The obtained material was characterized mechanically through compression tests, determining the elastic moduli of the composite, which was found to be between 16.4 and 20 GPa. Also, different physical characterization methods where employed to analyse the pore content which was found to be 18%. The obtained data was employed for the estimation of elastic moduli of the compound, and compared to the empirical results obtained with the mechanical tests.