Abstract: A refractory ceramic material, including a porous base refractory material and a zirconia protective layer covering walls of pores of the porous base refractory material, wherein the refractory ceramic material has a porosity of not less than 80%, and the zirconia protective layer has a thickness not more than about 1 nanometer.

Abstract: A process for manufacturing a refractory material adapted for contact with a molten ferrous metal, comprising the steps of: impregnating the base refractory material with a zirconium containing solution, the base refractor material having a porosity of not less than 85% and not more than 95%, drying the impregnated base refractory material at a temperature of 800.degree.-900.degree. C. for two to six hours to form a zirconia protective layer covering walls of pores in the base refractory material.

Abstract: The invention relates to a process for manufacturing an insulating fibrous piece based on fibers resisting high temperature, which consists in: preparing a first suspension containing a first type of fibers resisting high temperature; preparing at least one second suspension containing a second type of fibers resisting high temperature; then pouring each suspension into a distinct compartment of a vat of which the bottom comprises a momentarily obstructed filtering sieve and of which the elementary compartments are separated from one another by a removable plate, said process being characterized in that: each suspension also comprises a minority proportion of ceramizable particles; whilst withdrawing the removable separating plate, the medium is stirred locally at least in the vicinity of this separation plate, on the one hand, and, simultaneously, the water is drained through the filtering sieve, on the other hand, in known manner; and, after having dried the piece obtained, it is heated to a temperature cap

Abstract: An insulating structure is provided which includes a succession of superposed layers of fibers capable of withstanding high temperatures. A hot face of the structure comprises fibers capable of withstanding temperatures higher than the fibers of the cold face. The layers have an apparent density which varies from the hot face to the cold face. The structure contains fibers which have temperature-resistant properties which progressively decrease from the hot face to the cold face. The structure according to this invention can advantageously be applied to line ovens.

Abstract: Ceramic composite material characterized in that it comprises a core of ceramic fibers of which at least one face is coated with a hard and dense ceramic slip covering, of which the coefficient of expansion is compatible with that of the ceramic fibers.