| abstract |
Machinable ceramics with 30-60 vol.% of fine crystals of fluorophlogopite, a synthetic mica, evenly dispersed in a vitreous matrix is produced using as principal raw materials kaolin and activated clay, which are natural minerals, other than metal oxides themselves. According to the production process, a mixture of fine particulate raw materials is calcined under first heat treatment conditions in which a maximum temperature is in the range of 1,000-1,100°C. The raw materials include kaolin and activated clay as principal raw materials, Mg-containing, K-containing and F-containing compounds as auxiliary raw materials and B₂O₃ as a sintering aid. The resulting calcined mass is ground into fine particles, followed by the formation of a green body of a desired shape. The green body is then sintered into a fired body under second heat treatment conditions in which a maximum temperature is in the range of 1,100-1,250°C. |