POROUS CERAMIC AND PROCESS FOR PRODUCING THE SAME

摘要

A porous ceramic combining a high porosity with a high strength and serving as a catalyst support or a filter for removing foreign matter from fluid. A porous ceramic having a porosity of 30 % or above comprises mainly columnar ceramic particles having an aspect ratio of 3 or above. In particular, a porous silicon nitride ceramic comprises mainly Si3N4 wherein prismatic beta -Si3N4 particles amount to at least 60 % of the total amount of silicon nitride particles and further contains at least one compound of a rare earth element in an amount of 1-20 vol.% in terms of the oxide of the rare earth element. The silicon nitride ceramic may further contain at least one compound of a group IIa, group IIIb or transition metal element in an amount of at most 5 vol.% in terms of the oxide of the element. The porous silicon nitride ceramic is produced by heat-treating a molding of a powdery mixture comprising powdery silicon nitride and a powdery rare earth compound at 1,500 DEG C or above in a nitrogen-containing atmosphere.