Abstract: A part includes a substrate of ceramic matrix composite material, the substrate including silicon, the part further including an environmental barrier formed on at least one surface of the substrate, wherein the environmental barrier includes at least one compound selected from Yb2-2?Gd2?SiO5 and Yb2-2?Gd2?Si2O7, where ? is between 0.05 and 0.15, and wherein the environmental barrier further includes alumina Al2O3, the molar alumina content being between 5% and 15% of the total environmental barrier composition.

Abstract: A part includes a substrate, having, adjacent to a surface of the substrate, at least a portion that is made from a material that contains silicon, and an environmental barrier formed on the surface of the substrate, the environmental barrier including at least a first layer including a rare earth disilicate of formula REa2Si2O7 present at a molar content lying in the range 70% to 99.9%, where REa is a rare earth element; and at least one rare earth oxide of formula REb2O3 present at a molar content lying in the range 0.1% to 30%, where REb is a rare earth element different from REa.

Abstract: A part includes a substrate having, adjacent to a surface of the substrate, at least a portion that is made of a material that contains silicon, and an environmental barrier formed on the surface of the substrate, the environmental barrier including a first layer including at least one first rare earth silicate and presenting grains with a mean size less than or equal to 1 ?m; and a second layer covering the first layer, the second layer including at least one rare earth silicate and presenting grains with a mean size greater than 1 ?m.

Abstract: A composite material part includes fiber reinforcement made of carbon or ceramic yarns and a matrix that is mostly ceramic, the part further including a first interphase layer covering the yarns and present between the yarns and the matrix, the first interphase layer being a layer of boron nitride doped with aluminum and presenting an atom content of aluminum lying in the range 5% to 15%.

Abstract: A composite material part includes fiber reinforcement made of carbon or ceramic yarns and a matrix that is mostly ceramic, the part further including a first interphase layer covering the yarns and present between the yarns and the matrix, the first interphase layer being a layer of boron nitride doped with aluminum and presenting an atom content of aluminum lying in the range 5% to 15%.

Abstract: A part includes a substrate having, adjacent to a surface of the substrate, at least a portion that is made of a material that contains silicon, and an environmental barrier formed on the surface of the substrate, the environmental barrier including a first layer including at least one first rare earth silicate and presenting grains with a mean size less than or equal to 1 ?m; and a second layer covering the first layer, the second layer including at least one rare earth silicate and presenting grains with a mean size greater than 1 ?m.

Abstract: A part includes a substrate, having, adjacent to a surface of the substrate, at least a portion that is made from a material that contains silicon, and an environmental barrier formed on the surface of the substrate, the environmental barrier including at least a first layer including a rare earth disilicate of formula REa2Si2O7 present at a molar content lying in the range 70% to 99.9%, where REa is a rare earth element; and at least one rare earth oxide of formula REb2O3 present at a molar content lying in the range 0.1% to 30%, where REb is a rare earth element different from REa.

Abstract: A part including a substrate in which at least a portion adjacent to a surface of the substrate is made of a refractory material containing silicon, is protected by an environmental barrier formed on the surface of the substrate and having at least a self-healing layer containing a rare earth silicate. The self-healing layer is formed: for at least 90 mol %, by a system constituted by 30 mol % to at most 80 mol % of at least one rare earth silicate RE2Si2O7, RE being a rare earth, and at least 20 mol % to 70 mol % of manganese oxide MnO; and for at most 10 mol %, by one or more oxides other than MnO, having a eutectic point with SiO2 less than or equal to 1595° C.; the self-healing layer presenting a liquid phase having a self-healing function at least throughout the temperature range 1200° C. to 1400° C., while conserving a majority solid phase.

Abstract: A refractory material that can withstand high temperatures in an oxidizing medium and containing at least: a first constituent corresponding to hafnium, or to a non-oxide compound of hafnium, or circular in a or a non-oxide compound of zirconium, or corresponding to a mixture of at least two metals and/or compounds selected from hafnium a non-oxide compound of hafnium, zirconium, and a non-oxide compound of zirconium; a second constituent corresponding to the boron or to a non-oxide compound of boron, or corresponding to a mixture of boron and a non-oxide compound of boron; and a third constituent corresponding to a rare earth RE or to a non-oxide compound of the rare earth RE, or corresponding to a mixture of rare earth RE and a non-oxide compound of the rare earth RE, where RE is selected from scandium, yttrium, and the lanthanides. The material contains neither silicon nor a compound of silicon.

Abstract: A part including a substrate in which at least a portion adjacent to a surface of the substrate is made of a refractory material containing silicon, is protected by an environmental barrier formed on the surface of the substrate and having at least a self-healing layer containing a rare earth silicate. The self-healing layer is formed: for at least 90 mol %, by a system constituted by 30 mol % to at most 80 mol % of at least one rare earth silicate RE2Si2O7, RE being a rare earth, and at least 20 mol % to 70 mol % of manganese oxide MnO; and for at most 10 mol %, by one or more oxides other than MnO, having a eutectic point with SiO2 less than or equal to 1595° C.; the self-healing layer presenting a liquid phase having a self-healing function at least throughout the temperature range 1200° C. to 1400° C., while conserving a majority solid phase.

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 refractory material that can withstand high temperatures in an oxidizing medium and containing at least: a first constituent corresponding to hafnium, or to a non-oxide compound of hafnium, or circular in a or a non-oxide compound of zirconium, or corresponding to a mixture of at least two metals and/or compounds selected from hafnium a non-oxide compound of hafnium, zirconium, and a non-oxide compound of zirconium; a second constituent corresponding to the boron or to a non-oxide compound of boron, or corresponding to a mixture of boron and a non-oxide compound of boron; and a third constituent corresponding to a rare earth RE or to a non-oxide compound of the rare earth RE, or corresponding to a mixture of rare earth RE and a non-oxide compound of the rare earth RE, where RE is selected from scandium, yttrium, and the lanthanides. The material contains neither silicon nor a compound of silicon.

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.