Porous ceramic articles and method for making same

Abstract

There is disclosed a fired ceramic article such as a mold or die having no surface flaws; a uniform open porosity of at least 20% by volume, average pore size in the range of 1-10 microns, high abrasion resistance, a modulus of rupture of at least 4,000 psi; the fired article being substantially the same size as the corresponding unfired article and consisting essentially of 30 to 90% by weight of refractory abrasive particles such as alumina and 70 to 10% by weight of glass particles, said glass particles containing crystals grown during firing of the article, thereby greatly increasing the strength of the article, said particles being bonded by sintering while said particles are in the solid state. There is also disclosed a method for producing the fired ceramic article which includes the steps of forming a mixture of from 30 to 90% abrasive particles and 70 to 10% of glass particles (by weight based on the total amount of abrasive particles and glass particles) and adding a sufficient amount of organic binding agent and water to form, for example, a mold or die of desired shape, removing the organic binder and water by raising the temperature of the mold or die at a rate whereby the entire mold or die has substantially the same temperature and until the mold or die reaches a temperature above which the binder vaporizes and below and near the fusion range of the glass, and holding the article at this temperature until a solid state bond is formed because of sintering between the particles.