Abstract: A method of treating ceramic fibers based on metal carbide, the method including a first reagent gas heat treatment performed with at least one first reagent gas of the halogen type that chemically transforms the surface of the fiber to obtain a surface layer constituted mainly of carbon, and a second reagent gas heat treatment performed with at least one second reagent gas that eliminates the surface layer formed during the chemical transformation.

Abstract: The invention relates to a method of fabricating a part including at least one face in the form of a surface of revolution from a structure made up of a plurality of thin-walled hollow bodies. In order to ensure that cutting takes place without damaging the walls and/or the bonds between the walls of the hollow bodies, the part is machined in the structure by means of a water jet. More precisely, during machining, the structure is attacked with a jet of water under pressure that is directed tangentially relative to the outer envelope of said at least one face to be made in the form of a surface of revolution.

Abstract: A method of densifying a porous substrate with pyrolytic carbon includes loading the substrate into an oven, admitting a reaction gas mixture to the oven, extracting an effluent gas from the oven, and recycling components of the effluent gas into the reaction gas mixture. The reaction gas mixture contains a pyrolytic carbon precursor gas together with a vector gas. The effluent gas contains residual components of the reaction gas mixture together with reaction products, including hydrogen. The recycling is performed after eliminating heavy hydrocarbons contained in the effluent gas.

Abstract: A method of fabricating a turbomachine blade out of a composite material including fiber reinforcement densified by a matrix, the method including making a one-piece fiber blank by three-dimensional weaving; shaping the fiber blank to obtain a one-piece fiber preform having a first portion forming a blade airfoil and root preform and at least one second portion forming a preform for an inner or outer blade platform; and densifying the preform with a matrix to obtain a composite material blade having fiber reinforcement constituted by the preform and densified by the matrix, fowling a single part with incorporated inner and/or outer platform.

Abstract: In order to provide a self-healing layer on a composite material part, a composition is applied to the part, the composition containing: a suspension of colloidal silica; boron or a boron compound in powder form; silicon carbide in powder form; and at least one ultra-refractory oxide.

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 plurality of unidirectional sheets (30a, 30b, 30c) are superposed in different directions and they are bonded together. At least one of the unidirectional sheets is made by spreading a tow so as to obtain uniform thickness, width not less than 5 cm, and a weight of no more than 300 g/m2, cohesion being imparted to the sheet so as to enable it to be handled prior to being superposed with other sheets. Advantageously, the unidirectional sheets are made of carbon fibers and are obtained by spreading out large tows.

Abstract: The invention relates to a method of making a casing-and-diverging-portion unit, the method comprising the following steps: forming fiber reinforcement from a first fiber preform made with a first type of fiber and a second fiber preform made with a second type of fiber different from the first type of fiber, said second preform being placed on the first preform; maintaining the fiber reinforcement in tooling so that it has a shape identical to the shape of the casing-and-diverging-portion unit that is to be made; and impregnating said fiber reinforcement with a thermosetting resin and impregnating the resin.

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: 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: 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 an electrolysis installation comprising at least two rows of electrodes that are immersed at least in part in a liquid electrolyte giving off one or more gaseous species of corrosive nature at the electrodes, at least one separation membrane being disposed between two adjacent rows of electrodes. Each membrane is constituted by carbon fiber reinforcement stiffened by a carbon matrix and presents porous portion that is permeable to ions and impermeable to the or each gaseous species, given off at the electrolytes.

Abstract: The invention provides a method of making a fiber ply for forming a preform of a composite part in the form of a body of revolution having a non-developable surface, the method being characterized in that it comprises the steps consisting in: defining an annular space (23) with first and second canvases (20, 21) respectively defining an inner periphery and an outer periphery thereof; placing fibers between the canvases (20, 21) by placing the fibers in the annular space in at least one direction and by holding said fibers on the canvases by stitching; implementing circular connection stitching in the vicinity of the inner periphery of the annular space (23); and cutting out the fiber ply as made in this way in the annular space (23) in order to extract it from the canvases.

Abstract: The invention relates to a device for supporting electrodes in an electrolysis installation, said support comprising a busbar having electrodes fastened thereto, said electrodes being disposed on either side of the busbar and extending vertically below said busbar, the busbar and said electrodes being designed to be immersed at least in part in an electrolyte that gives off one or more gaseous species of a corrosive nature. The device further comprises a protective element of carbon/carbon material placed under the busbar, the protective element being of length and width that are not less than the length and the width of the busbar.

Abstract: An after-body assembly for an aeroengine, the assembly including, in an axial direction, an annular part made of metallic material secured to the aeroengine and an after-body part made of ceramic matrix composite material presenting the form of a body of revolution at least in its upstream portion, the after-body part being mounted on the annular part by resiliently flexible fastener tabs, each fastener tab having a first end fastened to the annular part and a second end fastened to the upstream portion of the after-body part, wherein each fastener tab includes an axial abutment element extending radially from the second end of the tab, the axial abutment element facing the first end and a radial abutment element at the second end of the tab, the radial abutment element overlying the first end in a radial direction.

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 fiber preform obtained by conforming panels of fiber texture on a former having a surface that reproduces the shape desired for a surface of the nozzle or the nozzle divergent section that is to be made, and by bonding the panels together via their mutually contacting edges, and consolidated fiber reinforcement is formed by shaping the fiber preform impregnated with a consolidation composition comprising a resin, shaping being performed between the former and a jacket applied against the impregnated fiber preform so as to obtain consolidated fiber reinforcement having a fiber volume percentage of at least 35%, and having a thickness of no more than 5 mm over at least a major fraction of its axial dimension. The densification of the fiber reinforcement is continued by chemical vapor infiltration after pyrolyzing the resin so that once densified a part is obtained that has practically the shape and the wall thickness of the nozzle or the nozzle divergent section that is to be made.

Abstract: The invention relates to an acoustic panel (20) for an ejector nozzle (10) comprising the following main components: an external skin (22) containing acoustic holes (29); an internal skin (23); an acoustic structure (21) comprising alveolar-core cells (27) between the internal skin (23) and the external skin (22). At least one main component selected from the external skin (22), the internal skin (23) and the acoustic structure (21) is formed by a composite material and the acoustic structure (21) is held in contact with either or both of the internal (23) and external (22) skins by compression by elastic means and/or by fixing by mechanical fixing means (24). The invention also relates to an injector nozzle (10) and a nacelle (1) comprising such an acoustic panel (20).

Abstract: A method of obtaining fiber textures of carbon from a cellulose precursor includes the steps of: spinning cellulose filaments (12) from a viscose solution or a cellulose solution; subjecting the cellulose filaments to washing in water (21); impregnating the washed and non-dried cellulose filaments with an aqueous emulsion (41) of at least one organosilicon additive; drying the impregnated cellulose filaments; and obtaining a fiber texture made up of impregnated and dried cellulose filaments prior to carbonization.

Abstract: A method of manufacturing nuclear fuel elements comprising the steps of placing nuclear fuel balls in the container made from ultra-porous material, applying a CVI to the container and removing the container. The container for manufacturing fuel elements comprising balls, and is produced from at least one ultra-porous material, for example carbon foam.