Abstract: A part for an aircraft turbojet engine nacelle is made of a composite material and includes at least one outer face (S1), a fibrous preform including fiber locks and having a surface(s) delimiting depressions between fiber locks, a covering material which at least partially covers the surface(s) of the fibrous preform and in particular the depressions, and a matrix which binds entirely the covering material and the fibrous preform. The covering material is a fibrous mat and the outer face (S1) is smooth. A method for manufacturing such a part includes manufacturing the fibrous preform, providing a fibrous mat, depositing the fibrous preform and fibrous mat in a mold, dispersing the matrix between the fibers of the preform and mat and consolidating the fibrous preform and mat.

Abstract: An assembly for an aircraft turbojet engine is described. The assembly includes a central gas-exhaust element and a connecting flange interposed between, upstream, a metallic outlet of a turbojet engine and, downstream, the central element. The connecting flange consists of an annular part and flexible lugs having axially: a first end where the lug is connected to the annular part, and a second free end, projecting radially outwards from the first end and towards which the lug is fixed with the central element.

Abstract: A process for manufacturing a composite part includes arranging a fibrous preform in a mold including an impregnation chamber which includes in its lower part a filter by making a first face of the preform rest on the filter, the impregnation chamber being closed by a flexible membrane placed opposite a second face of the preform, the membrane separating the impregnation chamber from a compaction chamber. The process further includes injecting a compression fluid into the compaction chamber so as to apply a first pressure on the membrane and injecting a slurry including ceramic particles into the impregnation chamber with a second pressure while maintaining the injection of the compression fluid, the second injection pressure of the slurry being lower than the first pressure on the membrane.

Abstract: A process for manufacturing a composite material part including a particulate reinforcement densified by a ceramic matrix, the process including: formation of a blank of the part to be manufactured by shaping a mixture including a binder, first ceramic or carbon particles intended to form the particulate reinforcement of the part and second ceramic or carbon particles distinct from the first particles, removal or pyrolysis of the binder present in the blank to obtain a porous preform of the part to be manufactured, and infiltration of the porosity of the preform by a molten composition including a metal in order to obtain the part.

Abstract: A method of fabricating a composite part, includes forming a fiber preform for the part that is to be obtained by depositing a plurality of fiber structures impregnated with a thermoplastic polymer onto a surface, with deposition being performed by automated fiber placement; eliminating the thermoplastic polymer present in the preform by dissolution with a solvent; and injecting a liquid impregnation composition into the pores of the fiber preform after eliminating the thermoplastic polymer in order to form a matrix in the pores of the fiber preform.

Abstract: An installation for depositing a shaped filled roving intended to be used to manufacture a composite-material component, includes a device for feeding a fibrous roving impregnated with a composition including a binder and ceramic or carbon fillers, a die for shaping and draining the binder defined by at least one porous surface, the die having an evolving section between an inlet section and an outlet section, the inlet section being larger than the outlet section, a support in communication with the die outlet on which the shaped roving is to be deposited, and a first conveying device configured to convey the roving from the feed device through the die and to the support.

Abstract: A fiber structure includes a plurality of weft layers and of warp layers interlinked by multilayer three-dimensional weaving, the fiber structure having at least first and second portions that are adjacent in the warp direction, the first portion presenting, in a direction perpendicular to the warp and weft directions, a thickness that is greater than the thickness of the second portion, wherein the first portion has at its core at least one fiber fabric obtained by three-dimensional weaving of warp yarns and weft yarns in the form of a Mock Leno weave grid, the at least one fabric being present between two skins present at the surface of the first portion and being linked to the skins by warp yarns belonging to the skins that are locally deflected into the fabric.

Abstract: A part made of composite material includes fiber reinforcement including silicon carbide fibers presenting an oxygen content less than or equal to 1 % in atomic percentage; and a matrix present in the pores of the fiber reinforcement and including at least one sintered silicate phase including at least one rare earth silicate, mullite, or a mixture of mullite and of at least one rare earth silicate, the matrix including at least a first phase including mullite and a second phase, different from the first phase, including at least one rare earth silicate.

Abstract: A shaping tooling for chemical vapor infiltration of a fiber preform includes a structural enclosure formed by supports each provided with a multiply-perforated zone. Each of the supports has in its inside face an uncased zone that includes the multiply-perforated zone. The shaping tooling further includes first and second shaping mold functional elements, each present in a respective one of the uncased zones of the support. Each shaping mold functional element has a first face of a determined shape corresponding to the shape of the part that is to be made and a second face that is held facing the inside face of a support. Each functional element has a plurality of perforations and presents a number of perforations, a size of perforations, or a shape of perforations that differs from the number, the size, or the shape of the perforations present in the facing support.

Abstract: A process for manufacturing a composite part includes introducing an adhesion promoter into the pores of a fibrous preform formed by threads covered with a coating having —OH groups on its surface, the adhesion promoter including an electron-withdrawing group G1 that is reactive according to a reaction of substitution or of nucleophilic addition with the —OH groups, and a reactive group G2; grafting the adhesion promoter to the surface of the coating by a reaction of substitution or nucleophilic addition of the —OH groups on the group G1; introducing a ceramic precursor resin into the pores of the fibrous preform; polymerizing the resin introduced and bonding the grafted adhesion promoter to the resin by chemical reaction between these two compounds at the level of the group G2, and forming a ceramic matrix phase in the pores of the fibrous preform by pyrolysis of the polymerized resin.

Abstract: A turbine ring assembly includes a plurality of ring sectors of ceramic matrix composite material forming a turbine ring and a ring support structure secured to a turbine casing and having two annular flanges, each ring sector having two tabs held between the two annular flanges. The ring support structure includes an annular retention band mounted on the turbine casing, the annular retention band including an annular web forming one of the flanges. The two annular flanges exert stress on the tabs of the ring sectors. One of the flanges is elastically deformable in the axial direction of the turbine ring. The band has a first series of teeth distributed circumferentially on the band and the turbine casing has a second series of teeth distributed circumferentially on the casing, and the teeth of the first series and the teeth of the second series together provide circumferential jaw coupling.

Abstract: A structure for the nacelle of an aircraft propulsion unit includes a first skin and stiffeners arranged to hold acoustic treatment modules against the first skin. Each acoustic treatment module includes a honeycomb core and a second skin, such that the honeycomb core is sandwiched between the first skin and the second skin. Such a structure allows the structural reinforcement function provided by the stiffeners to be separated from the acoustic treatment function performed by the acoustic treatment modules which are simply bearing on the first skin.

Abstract: A panel for a nacelle of an aircraft propulsion assembly includes two skins and a cell structure provided with transverse partitions defining cells. The cell structure includes folds with at least one central part forming at least one part of at least one transverse partition and at least one peripheral part extending along at least one of the skins. A nacelle with such a panel is provided, as well as a method for manufacturing such a panel.

Abstract: The invention relates to a method for producing a hollow part made of a ceramic matrix composite material comprising the steps of: shaping a hollow fibrous preform, a core of oxidizable material being housed or inserted into the preform (E1); consolidating said preform (E3, E4); and extracting the core by oxidising said core (E5).

Abstract: Method for manufacturing a CMC, i.e. ceramic matrix composite material, part provided with at least one cutout, as well as to such a CMC part provided with at least one cutout, the method comprising the following steps: providing (E1) a fibrous reinforcement (10), forming (E2?) a cavity in a portion of the fibrous reinforcement (10), injecting (E3) a slip comprising at least a ceramic powder and a solvent, the slip being injected so as to impregnate the fibrous reinforcement (10?) and to fill the cavity of the fibrous reinforcement (10?), drying (E4) the obtained assembly, carrying out a densification (E6) by infiltration of a liquid densification material and solidification of said densification material, machining (E7) at least one cutout in the obtained blank (30) within the volume corresponding to the cavity of the fibrous reinforcement (10).

Abstract: A turbine ring sector made of ceramic matrix composite material has a portion forming an annular base with an inner face for defining the inner face of a turbine ring when the ring sector is mounted on a ring support structure and an outer face from which there extends an attachment portion for attaching the ring sector to the ring support structure, the ring sector further including inter-sector faces, each for facing a neighboring ring sector when the ring sector is mounted on the ring support structure; wherein the inter-sector faces are coated in an environmental barrier that is doped with an electrically-conductive compound and that presents at least one slot.

Abstract: A method of fabricating a ceramic material, the method including forming a ceramic material by performing a first chemical reaction at least between a first powder of an intermetallic compound and a reactive gas phase, a liquid phase being present around the grains of the first powder during the first chemical reaction, the liquid gas phase being obtained from a second powder of a metallic compound by melting the second powder or as a result of a second chemical reaction between at least one element of the first powder and at least one metallic element of the second powder, a working temperature being imposed during the formation of the ceramic material, which temperature is low enough to avoid melting the first powder.

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 turbine ring assembly includes both a plurality of ring sectors made of ceramic matrix composite material forming a turbine ring and also a ring support structure having two annular flanges, each ring sector having two tabs held respectively between the two annular flanges of the ring support structure. The two annular flanges of the ring support structure exert stress on the tabs of the ring sectors. One of the flanges of the ring support structure is elastically deformable in the axial direction of the turbine ring. The turbine ring assembly further includes a plurality of pegs engaged both in the annular flanges of the ring support structure and in the tabs of the ring sectors facing the annular flanges.

Abstract: The present disclosure relates to a cell structure for an acoustic attenuation device for a nacelle of an aircraft propulsion assembly. This cell structure includes lateral partitions forming channels that each extend between a first end and a second end and skin elements arranged so that each channel is at least partly closed at the first end thereof by at least one skin element. Each skin element is connected to a respective lateral partition and can move relative to the other lateral partitions. A continuous skin can be assembled on this cell structure so as to at least partly close the channels at the second end thereof and to thus form an acoustic attenuation device.