Japanese Universities Develop Ti-based Metallic Glass for Artificial Finger Joint

Jun 11, 2009
Masaaki Maruyama, Nikkei BP Producer
The artificial finger joint prototype made of Ti-based metallic glass. The saddle-shaped structure on the upper side is a joint surface, and the columnar portion on the lower side is the insertion part (photo courtesy of the Institute for Materials Research of Tohoku University).
The artificial finger joint prototype made of Ti-based metallic glass. The saddle-shaped structure on the upper side is a joint surface, and the columnar portion on the lower side is the insertion part (photo courtesy of the Institute for Materials Research of Tohoku University).
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Tohoku University, Tokyo Institute of Technology and Osaka University jointly developed titanium (Ti)-based metallic glass that is suitable for use in living organisms and prototyped an artificial finger joint with this new material.

The Institute for Materials Research of Tohoku University optimized the composition, etc, of the Ti-based metallic glass so that it is suitable for use as a biomedical material.

With the new metallic glass, the Materials and Structures Laboratory of Tokyo Institute of Technology developed a surface processing technology for a bioactive membrane that can be formed into a strong junctional membrane used between bones. The Joining and Welding Research Institute of Osaka University developed a surface treatment technique to facilitate the formation of the strong junctional membrane.

Based on those research results, the universities prototyped an artificial finger joint and confirmed that the metallic glass can be firmly joined to bone apatite, etc.

The Institute for Materials Research optimized the composition of Ti-based metallic glass (Ti40Zr10Cu36Pd14; titanium, zirconium, copper and palladium in atomic percent) that is about three times as strong as titanium and has an elastic modulus nearly equivalent to that of bones.

According to the universities, the new metallic glass is "believed to be noncarcinogenic" because it does not contain nickel (Ni), unlike stainless steel, which has been used for artificial joints thus far.

In addition, compared with titanium alloy, which is pervasively used for artificial joints, the new metallic glass "has advantages that it does not produce abrasion powder by sliding movements thanks to its superior wear resistance, and that it has a higher resistance to deformation and fractures because its elastic modulus is nearly equivalent to that of bones," according to the universities.

Furthermore, the metallic glass has a forming processability that is suitable for near-net-shape forming because it entails no volume shrinkage at solidification, according to the universities.

The Materials and Structures Laboratory "developed, for the first time in the world, a surface processing technology to provide a nano-sized mesh-type bioactive membrane" on the surface of a columnar insertion part that constitutes the lower side of the artificial finger joint, according to Nobuhiro Matsushita, an associate professor at Tokyo Institute of Technology.

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