| abstract |
The present invention provides a method for producing a polycrystalline body having excellent denseness. A preparation process, a mixing process, a molding process, and a heat treatment process are performed. In the preparation step, coarse particle powder made of ceramics and fine particle powder having an average particle size equal to or less than 1/3 of the average particle size are prepared. In the mixing step, coarse particle powder and fine particle powder are mixed to prepare a raw material mixture. In the molding step, the raw material mixture is molded. In the heat treatment step, the compact is heated and sintered to produce a polycrystalline body. Further, in the heat treatment process, the temperature raising process and the first holding process are performed, and the second holding process and / or the cooling process are performed. In the temperature raising process, heating is started to raise the temperature, and in the first holding process, the temperature is held at T1 ° C. In the second holding process, the temperature is held at a temperature T2 ° C. lower than the temperature T1 ° C. In the cooling process, cooling is performed at a temperature drop rate of 60 ° C./h or less from the temperature T1 ° C. [Selection] Figure 1 |