| 摘要 |
PROBLEM TO BE SOLVED: To obtain a sintered compact having lessened warpage and roundness defect by turning over a blind tubular ceramic molding and firing this molding while supporting the molding with the inside surface of its base, thereby generating the tensile force in an axial direction by its own weight in the molding and offsetting the stress to generate warpage by this tensile stress. SOLUTION: A core material 1 of an inverted Tee shape is placed in a firing furnace and the blind tubular ceramic molding 3 is put on this core material 1. Further, a firing vessel 2 is put thereon. Since the core part is longer than the internal length of the molding 3, the total mass of the molding 3 is supported at the front end of the core material 1 with the inside surface of the bottom as a fulcrum. Firing is executed in this state. At this time, (P.T)/S<=1.05 is preferably satisfied when the outside diameter of the core material 1 is defined as S and the firing shrinkage rate of the molding 3 as T. If the molding has a compsn. turning to β alumina after the firing, the vapor of sodium oxide is generated in the process of the firing and, therefore, the material of the core material 1 is most adequately a magnesium sintered compact of >=99% in purity. |
