Abstract: A method of smoothing the surface of a ceramic matrix composite material part that presents a surface that is undulating and rough. The method includes depositing a refractory vitreous coating on the surface of the part, the vitreous coating essentially containing silica, alumina, baryte, and lime.

Abstract: A method of fabricating a composite-material turbomachine blade having platform incorporated therein includes separately making a blade platform element that comprises rigidified fiber reinforcement and that has a shape close to that of a platform of the blade to be fabricated, with at least one opening being formed through the platform element. The opening has the shape of the profile of the airfoil of the blade to be fabricated. Three-dimensional weaving is used to make a flexible fiber blank as a single piece that includes blade airfoil-and-root preform portions. The platform element is engaged, via its opening, on the flexible fiber blank while deforming it so as to assemble the platform element with the fiber blank. The fiber blank is shaped together with the platform element assembled thereon to obtain a blade preform of a shape that is close to the shape of the blade to be fabricated. After shaping, the blade preform is consolidated in its shape in a shaper.

Abstract: A method of fabricating a complex part out of composite material including three-dimensional woven fiber reinforcement densified by a matrix, the method including three-dimensionally weaving a continuous fiber strip including a succession of fiber blanks for preforms of a plurality of parts that are to be fabricated; subsequently cutting individual fiber blanks out from the strip, each blank being a one-piece blank; shaping a cut-out blank to obtain a one-piece fiber preform having a shape that is close to the shape of a part that is to be fabricated; consolidating the preform in the desired shape; and densifying the consolidated preform by forming a matrix by chemical vapor infiltration.

Abstract: A method of making a fiber structure by multilayer three-dimensional weaving, the fiber structure having a thickness in a direction perpendicular to the warp and weft directions that varies along the warp direction while conserving the same number of warp yarns that are woven at all points of the fiber structure along the warp direction, wherein during a transition in the warp direction from a first portion of the fiber texture to a second portion of the fiber texture having a thickness that is greater than the thickness of the first portion, the number of warp planes is decreased and the number of layers of warp yarns is increased without changing the number of warp yarns, by constituting at least one warp plane in the second portion with warp yarns taken from at least two different warp planes in the first portion.

Abstract: A method of smoothing the surface of a ceramic matrix composite part presenting a surface that is undulating and rough. The method includes forming a ceramic coating on the surface of the part, the coating being made by applying a liquid composition on the surface of the part, the composition containing a ceramic-precursor polymer and a factory solid filler, curing the polymer, and transforming the cured polymer into ceramic by heat treatment. The method further includes impregnating the ceramic coating with a liquid metallic composition.

Abstract: An interphase coating is formed by chemical vapor infiltration (CVI) on the fibers constituting a fiber preform, the interphase coating comprising at least an inner layer in contact with the fibers for embrittlement relief to the composite material, and an outer layer for bonding with the ceramic matrix. The fiber preform is then kept in its shape by the fibers provided with the interphase coating and is consolidated by being impregnated with a liquid composition containing a ceramic precursor, and by transforming the precursor into a ceramic matrix consolidation phase. The consolidated preform is then densified by an additional ceramic matrix phase. No support tooling is needed for forming the interphase coating by CVI or for densification after consolidation using the liquid technique.

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: A woven fibrous structure embodied in one piece, used for producing a composite material part and comprising an internal part or a core (72) and a part adjacent to the external surface thereof or a skin (74, 76), is formed by three-dimensional core weaving with at least one weave selected from interlock and multilayer weaves and by skin weaving with a weave which differs from the core weave and selected from a multilayer weave and a two-dimensional weave. It can be also formed by three-dimensional weaving with at least one core interlock weave (72) and weaving with a fabric-, satin or skin twill-type weave, wherein skin weaving is of a multilayer or two-dimensional type.

Abstract: A turbine ring assembly for a gas turbine, the assembly comprising a complete ring (10) forming a single piece of ceramic matrix composite material (CMC), a metal structure for supporting the CMC ring having metal annular supports (20, 30) between which the CMC ring is placed while allowing differential expansion at least in a radial direction between the CMC ring and the annular supports, means (40-42) for centering the CMC ring, and at least one element for preventing turning of the CMC ring about its axis.

Abstract: A turbine ring assembly for a gas turbine comprises a one-piece split ring (10) of ceramic matrix composite (CMC) material, a CMC wedge-shaped part (20) having flanks in contact with the ends of the ring, on either side of the split, so as to close the ring, and an annular metal support structure (40) surrounding the CMC ring and in contact therewith over the major fraction of its outline, the CMC ring being mounted with prestress in the metal structure, at least one element (26) exerting a resilient return force on the wedge-shaped part to keep it in contact with the ends of the CMC ring when the split opens under the effect of differential expansion between the annular metal structure and the CMC ring, and at least one element for preventing the CMC ring from turning about its axis.

Abstract: The method comprises: using chemical vapor infiltration to form a first continuous interphase on the fibers of a fiber structure made of refractory fibers, the interphase having a thickness of no more than 100 nanometers; impregnating the fiber structure with a consolidation composition comprising a carbon or ceramic precursor resin; forming a fiber preform that is consolidated by shaping the impregnated fiber structure and using pyrolysis to transform the resin into a discontinuous solid residue of carbon or ceramic; using chemical vapor infiltration to form a second continuous interphase layer; and densifying the preform with a refractory matrix. This preserves the capacity of the fiber structure to deform so as to enable a fiber preform to be obtained that is of complex shape, while nevertheless guaranteeing the presence of a continuous interphase between the fibers and the matrix.

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: A fiber reinforcing texture (10) woven as a single part for fabricating a composite material part having an inner portion (12), or core, made by three-dimensional weaving with yarns made up from discontinuous fibers, and a portion (14, 16) adjacent to an outside surface, or skin, made by weaving with yarns made up from continuous filaments.

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 interphase coating is formed by chemical vapor infiltration (CVI) on the fibers constituting a fiber preform, the interphase coating comprising at least an inner layer in contact with the fibers for embrittlement relief to the composite material, and an outer layer for bonding with the ceramic matrix. The fiber preform is then kept in its shape by the fibers provided with the interphase coating and is consolidated by being impregnated with a liquid composition containing a ceramic precursor, and by transforming the precursor into a ceramic matrix consolidation phase. The consolidated preform is then densified by an additional ceramic matrix phase. No support tooling is needed for forming the interphase coating by CVI or for densification after consolidation using the liquid technique.

Abstract: The invention relates to a method of brazing together two parts (10, 20), the method being characterized in that a pad (30) is interposed between the two surfaces (S10, S20) of the parts that are to be joined together, said pad being formed by a refractory fiber texture, and being at least in part in contact with a brazing composition (40), and heat treatment is performed to liquefy the brazing composition (40) so as to cause the molten brazing composition to be distributed by capillarity over the entire brazing area between the two parts (10, 20) covered by the pad (30).

Abstract: A fiber preform for constituting the fiber reinforcement of composite material is prepared and then consolidated by depositing sufficient matrix phase therein to bond the fibers together while not completely densifying the preform. Pins of rigid material are put into place through the consolidated preform and densification of the consolidated preform containing the pins is continued by depositing at least a ceramic matrix phase. Thereafter, at least a portion of each pin is eliminated so as to leave a calibrated perforation passing through the resulting part, the pins being made at least in part out of a material that can be eliminated by applying treatment that does not affect the ceramic material of the matrix.

Abstract: A porous fiber structure is consolidated by forming within a deposit of a refractory material by partially densifying the fiber structure in such a manner as to bond together the fibers of the fiber structure so as to enable the fiber structure to be handled without being deformed, while leaving empty the major fraction of the initial pore volume of the fiber structure, and rigid pins are implanted through the consolidated porous structure. A blank is obtained by reinforcing a fiber structure by implanting pins or by bonding together consolidated fiber structures, the bonding being performed by implanting pins. A composite material part is obtained by densifying the blank.

Abstract: A fiber preform constituting fiber reinforcement of a composite material part that is to be fabricated is made by superposing and bonding together fiber plies, and by densifying the needled preform by introducing a material constituting the matrix of the composite material into it. During the process of making the preform, a powder is dusted onto the surface of at least some of the plies, the powder comprising at least one ingredient selected from a solid resin in powder form and solid fillers in powder form. The powder is dusted onto the surface of the top ply of the preform that is being made, prior to superposing and needling at least one additional ply.

Abstract: A fiber preform for constituting the fiber reinforcement of composite material is prepared and then consolidated by depositing sufficient matrix phase therein to bond the fibers together while not completely densifying the preform. Pins of rigid material are put into place through the consolidated preform and densification of the consolidated preform containing the pins is continued by depositing at least a ceramic matrix phase. Thereafter, at least a portion of each pin is eliminated so as to leave a calibrated perforation passing through the resulting part, the pins being made at least in part out of a material that can be eliminated by applying treatment that does not affect the ceramic material of the matrix.