| 摘要 |
PROBLEM TO BE SOLVED: To prevent color forming in the surface layer of a sintered compact, to impact uniform breaking strength to the surface layer and interior and to reduce a margin to grind in the surface by firing silicon nitride ceramics in an atmosphere of nitrogen or argon while preventing the generation of a reduction atmosphere. SOLUTION: Silicon nitride ceramics is fixed in an atmosphere of nitrogen, argon, etc., while preventing the generation of a reducing atmosphere. Tungsten or superkanthal is preferably used as a heating element and a case for housing the ceramics is preferably made of a carbon-free material such as boron nitride, silicon nitride, aluminum nitride, sialon, alumina, magnesia or zirconia. The surface thickening of a specified element and the formation of a so-called surface layer can be prevented. The surface layer and interior of the resultant silicon nitride ceramic sintered compact have the same color tone. |
