| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a ceramic bracket having transparency higher than that of the conventional ceramic bracket made of alumina and having a fine appearance at the time of being fitted. <P>SOLUTION: By using aluminum, yttrium and garget having cubic crystal structure, a polycrystal body free from optical anisotropy is produced, so as to realize high transparency. In order to solve the problem on strength, that is, to prevent the breakdown at the time of orthodonics, the grain size of a sintered compact is reduced, so as to realize high strength. The high transparency and high strength YAG ceramic can be obtained, e.g., by subjecting easily sinterable synthetic fine powder as raw material powder to atmospheric sintering to a relative density of≥95%, and thereafter performing HIP (Hot Isostatic Press) treatment at relatively low temperature for suppressing the growth of grains. <P>COPYRIGHT: (C)2006,JPO&NCIPI</p> |
