Development of Titanium Foam for Biomedical Applications

Abstract

Much of the efforts have been made over the period to select an appropriate material for bone implants. Metals such as stainless-steel and Co-Cr alloys with good toughness were used initially. But, these materials have been faced rejection in long term fixations due to stress-shielding, corrosion and cell adhesion. Among other metals, titanium with its amazing set of properties proved to be an ideal candidate for bone implants. But its elastic modulus and thermal properties still differs from the bone leading to stress-shielding and oral burn syndrome. The shortcoming of titanium can be improved either by alloying addition or introduction of porosity. In this study, microporous titanium implants were prepared by adopting melting technique. Initially, alloys were developed by using different atomic percentages of filler element which were then removed by electrochemical dealloying. The result of this technique was formation of micro-size pores with open morphology throughout the implant. Porous metallic structure was developed and characterized successfully. XRD depict complete removal of filler element which also coincide with the weight loss calculations. These developed pores in titanium was also observed under SEM analysis. When the modulus of micro-porous structure was compared with human bone, it was proved that the presence of pores reduces the modulus without causing any major effect on the strength of implant. This introduction of porosity in titanium implants also causes a reduction in value of thermal diffusivity to the level of bone. Examination of the porous implants for cell proliferation under fluorescence microscope also observed to be successful that depicts bio compatibility of the prepared samples. Samples with porosity level 22%-42% are more suitable as their elastic modulus and thermal diffusivity becomes equal to the bone. Also, this porosity level supports cell adhesion process due to the availability of more sites. Thus, these implants are suggestive to be used for orthopedic and dental applications.