Abstract: In order to protect a substrate having at least a portion adjacent to a surface that is made of a refractory material containing silicon, while the substrate is in use at high temperature in a medium that is oxidizing and wet, there is formed on the surface of the substrate an environmental barrier that contains no boron and that has at least one layer that is essentially constituted by a system of oxides formed by at least one rare earth oxide, silica, and alumina, and that is capable of self-healing by maintaining the presence of at least one solid phase in a temperature range extending up to at least 1400° C. approximately.

Abstract: A method of fabricating a thermostructural composite material part includes making a fiber preform formed of yarns or tows and impregnated by a consolidating composition containing a carbon- or ceramic-precursor, transforming the carbon- or ceramic-precursor by pyrolysis, and then densifying the preform by chemical vapor infiltration. A consolidating composition is used that additionally contains refractory solid fillers in the powder form presenting mean grain size less than 200 nanometers and leaving, after pyrolysis, a consolidated solid phase in which the carbon or the ceramic derived from the precursor occupies a volume representing 3% to 10% of the apparent volume of the preform, and the solid fillers occupy a volume representing 0.5% to 5% of the apparent volume of the preform.

Abstract: An environmental barrier is formed on a substrate (10) of ceramic matrix composite material and comprises an outer anticorrosion protection layer (12) containing a compound of the type comprising an aluminosilicate of an alkali, or an alkaline-earth, or a rare-earth element. A bond sub-layer (14) is formed between the substrate (10) and the protection layer (12), the composition of the bond sub-layer varying from substantially pure silicon to substantially pure mullite between an inner face beside the substrate and an outer face, with the silicon content decreasing and the mullite content increasing.

Abstract: An environmental barrier for a substrate of ceramic matrix composite material containing silicon, in particular containing SiC, is formed by an anticorrosion protection layer containing an aluminosilicate type compound of an alkali or alkaline-earth or rare earth element, e.g. BSAS, with a chemical barrier forming layer of aluminum nitride being interposed between the substrate and the anticorrosion protection layer.

Abstract: In order to protect a substrate having at least a portion adjacent to a surface that is made of a refractory material containing silicon, while the substrate is in use at high temperature in a medium that is oxidizing and wet, there is formed on the surface of the substrate an environmental barrier that contains no boron and that has at least one layer that is essentially constituted by a system of oxides formed by at least one rare earth oxide, silica, and alumina, and that is capable of self-healing by maintaining the presence of at least one solid phase in a temperature range extending up to at least 1400° C. approximately.

Abstract: A method of fabricating a thermostructural composite material part includes making a fiber preform formed of yarns or tows and impregnated by a consolidating composition containing a carbon- or ceramic-precursor, transforming the carbon- or ceramic-precursor by pyrolysis, and then densifying the preform by chemical vapor infiltration. A consolidating composition is used that additionally contains refractory solid fillers in the powder form presenting mean grain size less than 200 nanometers and leaving, after pyrolysis, a consolidated solid phase in which the carbon or the ceramic derived from the precursor occupies a volume representing 3% to 10% of the apparent volume of the preform, and the solid fillers occupy a volume representing 0.5% to 5% of the apparent volume of the preform.

Abstract: An environmental barrier for a substrate of ceramic matrix composite material containing silicon, in particular containing SiC, is formed by an anticorrosion protection layer containing an aluminosilicate type compound of an alkali or alkaline-earth or rare earth element, e.g. BSAS, with a chemical barrier forming layer of aluminum nitride being interposed between the substrate and the anticorrosion protection layer.

Abstract: An environmental barrier is formed on a substrate (10) of ceramic matrix composite material and comprises an outer anticorrosion protection layer (12) containing a compound of the type comprising an aluminosilicate of an alkali, or an alkaline-earth, or a rare-earth element. A bond sub-layer (14) is formed between the substrate (10) and the protection layer (12), the composition of the bond sub-layer varying from substantially pure silicon to substantially pure mullite between an inner face beside the substrate and an outer face, with the silicon content decreasing and the mullite content increasing.

Abstract: The method comprises forming at least one external coating on the surface of the product to be protected, the coating being constituted by a composition mainly containing a mixture of phosphates, of silica, and of alumina belonging to a P.sub.2 O.sub.5 --SiO.sub.2 --Al.sub.2 O.sub.3 system, and, after drying, implementing heat treatment at a temperature that is sufficient at least to transform the external coating into an insoluble cement capable of forming a self-sealing glass. The external coating is formed of a liquid suspension that is applied by spray-painting or by means of a brush, the suspension containing said mixture of phosphates, of silica, and of alumina. Prior to forming the external coating, the product may be impregnated to the core within the residual open pores of the composite material, using a liquid solution of phosphates, of sodium, and of potassium.

Abstract: The manufacture of a refractory composite material protected against corrosion and comprising fibrous reinforcement densified by a matrix, comprises a step of forming, either within the matrix or at its surface, at least one continuous layer constituted by a ternary silicon-boron-carbon system obtained by chemical vapor deposition or infiltration. The elements silicon and boron are thereby distributed uniformly, with the boron content in the Si-B-C system being not less than 5% in atom percentage.

Abstract: A composite material containing carbon is protected against oxidation by forming, on the composite material, an inner layer, an intermediate layer containing boron or a boron compound, and an outer layer of silicon carbide. The inner layer formed on the composite material before the intermediate layer is formed, is made of a refractory carbide that does not contain boron and that is at least 60 microns thick, said inner layer insulating the intermediate layer from the carbon contained in the composite material.