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【原创】Japanese Develop Ti-based Metallic Glass for Artificial ...
Japanese Universities Develop Ti-based Metallic Glass for Artificial Finger Joint
6 11, 2009 17:48
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).
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.
By combining the existing hydrothermal synthesis method, which is conducted in a high-temperature, high-pressure environment, and an electrochemical process for applying voltage, the laboratory significantly improved the reactivity and succeeded in providing an amorphous titanium oxide layer on the surface of the Ti-based metallic glass.
Specifically, the laboratory "improved the joining strength between the metal and ceramic material by providing an intermediate layer that has an oxidized layer with a slightly different composition in the amorphous titanium oxide layer," Matsushita said. When the titanium oxide layer is covered with apatite, which is the main component of bones, the artificial finger joint and a bone can be firmly joined to each other. As a result, the universities saw their way clear to overcoming the difficulty of joining the metal to apatite.
The Joining and Welding Research Institute developed an elemental technology to form a periodic nanostructure based on self-assembly by applying a laser surface treatment on the surface of the insertion part of the artificial finger joint. Self-assembly means a phenomenon where a periodic structure is spontaneously formed when the surface energy is excited by laser radiation.
The surface formed with the periodic nanostructure is subjected to a surface treatment to provide a bioactive membrane. The institute confirmed that the joining strength between the artificial finger joint and a bone is increased because the apatite layer is formed on the surface of the insertion part, which fits into a finger bone.
According to the universities, a great number of achievements, including more than 70 research papers, more than 40 oral presentations and more than 20 patent applications, have been produced by the research and development on the prototype artificial finger joint made of the new Ti-based metallic glass. The basic patent application was jointly filed by the three research labs. They are titled "Bioactive Material" (Japanese patent application No 2007-232224) and "Bioactivation of Metallic Glass and Bioactive Metallic Material" (No 2007-232225).
This development was one of the achievements of the "Collaborative Research Project for the Development of Metallic Glass/Inorganic Material Joint Technology," which is being promoted by the three labs as a joint project for Japanese collaborative research laboratories. The joint project is scheduled to be conducted for five years, from fiscal 2005 to fiscal 2009.
Masaaki Maruyama, Nikkei BP Producer
[ Last edited by hslining on 2009-9-10 at 13:32 ] |
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