Preparing refractory insulating products having controlled porosity by the wet method

Claim 1

A process for preparing, by the wet method, non-sintered refractory products of controlled porosity having resistance to molten aluminum, aluminum-base alloys, zinc and zinc-base alloys, comprising the following steps: producing a solid mixture of a refractory aluminous cement and a ceramic mixture of: a refractory aggregate selected from the group consisting of tabular alumina, corindon, stabilized zirconia and calcium zirconate, and refractory ceramic polycrystalline fibers comprising at least 70% by weight alumina and at most 30% silica, the proportion of ceramic fibers being higher than 10% by weight of the amount of refractory aggregate, and the proportion of the ceramic mixture being between 10% and 70% by weight of the total mixture; dispersing said solid mixture in water; emulsifying the dispersed product by adding 0.5% to 3% by weight, in relation to the weight of the water, of a foaming agent which is stable in a medium of a pH greater than 3; stabilizing the emulsion by adding a stabilizing agent; molding and drying the product in a mould having lubricated walls; and firing the molded product at a temperature higher than 150° C. but lower than its sintering temperature.