Porosity and Tensile Properties of Rhizoid Porous Structure Fabricated Using Selective Laser Melting
Shinji Ishibashi*1, Keita Shimada*1, Hiroyasu Kanetaka*2,*3, Masaki Tsukuda*1, Takumi Mizoi*1, Masataka Chuzenji*1, Shoichi Kikuchi*4, Masayoshi Mizutani*1,, and Tsunemoto Kuriyagawa*3
*1Graduate School of Engineering, Tohoku University
6-6-01 Aramaki Aza-Aoba, Aoba-ku, Sendai, Miyagi 980-8579, Japan
*2Graduate School of Dentistry, Tohoku University, Sendai, Japan
*3Graduate School of Biomedical Engineering, Tohoku University, Sendai, Japan
*4Department of Mechanical Engineering, Faculty of Engineering, Shizuoka University, Hamamatsu, Japan
The reduced density of the autogenous bone around metal medical implants forces joint replacement patients to undergo revision surgery. The loss of bone density is caused by a significant difference in the elastic modulus between implants and autogenous bone. Various studies have attempted to reduce the elastic modulus of the implant to close the large gap in the two moduli. Porous metal is a promising material for reducing the elastic modulus of implants, but it is difficult to fabricate a closed-cell structure like bone using conventional porous metal fabrication methods. In this study, porous Ti-6Al-4V was prepared by selective laser melting, then its porosity was evaluated by X-ray computed tomography. Additionally, tensile test specimens of the porous structure were prepared and the effect of pores on the tensile properties was evaluated. Depending on the energy density, the structure of the porous body was found to form both closed- and open-cell structures. In the tensile specimens that showed the most favorable results, the elastic modulus was reduced by approximately 90%, and the tensile strength exceeded that of the annealed material. This indicates that a metal implant that has a low elastic modulus while maintaining strength can be obtained.
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