Abstract: An object of the present invention is to prevent particle generation from holes formed in a ceramic member. A ceramic member 2 has a hole 20A formed therein. The hole 20A has a diameter “d” in a range of 0.05 mm to 2 mm and a length “L” of 2 mm or more. The member 2 has an inner wall surface 1 facing the hole 20A and the inner wall surface comprises an as-sintered face.

Abstract: A sintered body having at least a first phase and a second phase contacting one another at an interface is produced. A shaped body having a first shaped phase and a second shaped phase is prepared. The shaped body is sintered to produce the sintered body. A slurry containing a sinterable inorganic powder, a dispersing medium and a gelling agent is filled in a mold and gelled so that the slurry is solidified to provide the first shaped phase.

Abstract: A process for degreasing ceramic molded bodies containing a large quantity of paraffin wax includes a constant-temperature heating conducted for a certain period of time appropriately determined according to the size and shape of the ceramic molded bodies, at a temperature immediately below the temperature for the ceramic molded bodies to begin contraction, essentially in a low temperature region wherein the contraction occurs due to liquefaction of the paraffin wax and optionally in a high temperature region wherein the contraction occurs due to thermal decomposition of the paraffin wax. According to the process of the invention, build-up of stress in the ceramic molded bodies by heating is prevented and a temperature gradient between the surface and the inside of the molded bodies is leveled, so that crack-free molded bodies are obtained with a shortened degreasing schedule.

Abstract: Silicon nitride sintered bodies including Si.sub.3 N.sub.4 and at least one element selected from Y.sub.2 O.sub.3, MgO, ZrO.sub.2. In the silicon nitride bodies, a J phase solid solution is present in an intergranular phase, which satisfies a relation of 0.65x.ltoreq.y.ltoreq.x+2 wherein y is an amount of J phase solid solution and x is an amount of Y.sub.2 O.sub.3 as an additive.