WO2018234669A1

WO2018234669A1 - Process for manufacturing a composite material part having one or more local thickness variations

Info

Publication number: WO2018234669A1
Application number: PCT/FR2018/051439
Authority: WO
Inventors: Erwan CAMUS; Bruno Jacques Gérard Dambrine; Martine Marie-José DAUCHIER
Original assignee: Safran Aircraft Engines
Priority date: 2017-06-19
Filing date: 2018-06-18
Publication date: 2018-12-27
Also published as: CA2971426A1

Abstract

A process for impregnating a fibrous texture (10) comprising the following steps: - placing a fibrous texture (10) in an impregnation chamber (101) of a mold (110), the impregnation chamber (101) being closed in the upper part thereof by an impermeable membrane that is at least partly deformable (140) placed opposite an exposed face (10a) of the fibrous texture (10), said membrane (140) separating the impregnation chamber (101) from a compaction chamber (102), - injecting a liquid composition (150) containing at least one precursor of a matrix material into the impregnation chamber, - injecting a compression fluid (160) into the compaction chamber (102) in order to force the liquid composition (150) to penetrate the fibrous texture (10) so as to obtain a fibrous preform (20) impregnated with said liquid composition. The fibrous texture (10) has, on the exposed face thereof (10a), an overthickness portion (11). The impermeable membrane (140) comprises a conformal portion (141) having a shape corresponding to the shape of the contour of the overthickness portion (11) present on the exposed face (10a) of the fibrous texture (10).

Description

Process for manufacturing a composite material part having one or more local thickness variations

Background of the invention

The present invention relates to a method of manufacturing a composite material part, that is to say comprising a fiber reinforcement formed from fibers densified by a matrix.

More specifically, the invention relates in particular to the manufacture of so-called "thermostructural" composite materials, namely materials having good mechanical properties and the ability to retain these properties at high temperature, such as carbon / carbon composite materials (C / C ) formed of carbon fiber reinforcement densified by a carbon matrix, the ceramic matrix composite materials (CMC) formed of a reinforcement of refractory fibers (carbon or ceramic) densified by an at least partially ceramic matrix and the materials Oxide / oxide type composites formed of a reinforcing fiber oxide (alumina) densified by an at least partially oxide matrix. The invention also relates to the manufacture of organic matrix composite materials (CMO), that is to say comprising a fibrous reinforcement densified by a matrix of organic nature.

A common process for obtaining composite material parts is the liquid process. The liquid process consists in producing a fibrous preform having substantially the shape of a part to be produced, and intended to constitute the reinforcement of the composite material, and to impregnate this preform with a liquid composition containing a precursor of the material of the matrix. The precursor is usually in the form of a polymer, such as a resin, optionally diluted in a solvent or a slurry-suspended filler. The transformation of the precursor into a matrix is carried out by heat treatment. Several successive impregnation cycles can be performed to achieve the desired degree of densification. By way of example, liquid carbon precursors may be relatively high coke level resins, such as phenolic resins, whereas liquid precursors of ceramics, in particular of SiC, may be polycarbosilane type resins (PCS). or polytitanocarbosilane (PTCS) or polysilazanes (PSZ). For organic matrix composite (CMO) materials, a thermoplastic or thermosetting resin is used to impregnate the fiber preform.

Finally, for the manufacture of composite parts of oxide / oxide type, the parts are generally produced by draping in a mold of a plurality of fibrous layers made from refractory oxide fibers, the layers being each impregnated with a pre-impregnated layer. slip loaded with refractory oxide particles.

In all cases, the impregnation of the fibrous preform with a precursor liquid composition of the matrix material is an important step in that it then conditions the homogeneity and the level of matrix present in the resulting material and, consequently, , the mechanical properties of the material. Indeed, the macroporosity rate present in the final material directly influences the mechanical properties of the material.

A process for impregnating a fibrous texture with a precursor liquid composition of matrix material is disclosed in US 2012/0217670 which describes the placement of a fibrous texture in an impregnation chamber of an injection tooling the impregnation chamber being separated from a compression chamber by an impermeable and flexible membrane. A matrix liquid precursor is injected directly into the preform via an injection port opening onto the underside of the preform. Part of the liquid precursor then directly impregnates the preform while another part of the liquid precursor spreads over the upper face of the preform causing the deformation of the membrane. A compression fluid is then injected into the compression chamber so as to exert pressure on the membrane and to cause a distribution of the liquid precursor throughout the volume of the fibrous texture.

However, this impregnation method does not allow to satisfactorily impregnate fibrous textures with large thickness variations resulting in a significant relief on the surface of the preform. In addition, this process is not suitable for the manufacture of oxide / oxide composite materials which consists in impregnating the fibrous texture with a slip loaded with refractory particles. oxide and remove the liquid phase of the slip of the texture to leave only the particles in the texture.

Obiet and summary of the invention

The object of the present invention is to remedy the aforementioned drawbacks by proposing a solution which makes it possible to impregnate fibrous textures having one or more portions of thickness variation, in a fast and reliable manner while allowing good control of the deposit and the distribution of the matrix precursor liquid composition in the fibrous texture to obtain a material with a very low macroporosity rate.

For this purpose, the invention proposes a process for impregnating a fibrous texture comprising the following steps:

placing a fibrous texture in an impregnation chamber of a mold, the impregnation chamber being closed in its upper part by an at least partly deformable impermeable membrane placed facing an exposed face of the fibrous texture said membrane separating the impregnation chamber from a compaction chamber,

injecting a liquid composition containing at least one precursor of a matrix material into the impregnation chamber between the exposed face of the fibrous texture and the membrane,

injecting a compression fluid into the compaction chamber, the fluid exerting a pressure on the membrane to force the liquid composition to penetrate the fibrous texture so as to obtain a fibrous preform impregnated with said liquid composition,

characterized in that the fibrous texture has on its exposed face at least a portion of extra thickness and in that the impermeable membrane comprises at least one shaped portion having a shape corresponding to the shape of the contour of said at least one portion of extra thickness present on the exposed face of the fibrous texture.

Thanks to the presence of one or more conformation portions in the membrane, the excess thickness portion or portions of a fibrous texture may be impregnated homogeneously like the rest of the texture, and without deformation or wrinkling at the level of the or the portions of extra thickness that may occur when a simple flat membrane is forced to deform excessively at one or more portions of excess thickness.

In addition, with the method of the invention, it is possible to impregnate with the same tooling fibrous textures having portions of different thicknesses, only the membrane being changed to adapt to the shape and dimensions of the texture to to impregnate, to permeate.

According to one embodiment of the impregnation method of the invention, each shaped portion of the impermeable membrane has a rigidity greater than the other portions of said membrane.

According to another embodiment of the impregnation process of the invention, the mold impregnation chamber comprises in its lower part a piece of porous material on which the texture rests, the liquid composition injected into the impregnation chamber comprising a slip containing a powder of refractory particles, the method further comprising draining the porous material part of the liquid from the slip passed through the fibrous texture and retaining the powder of refractory particles within said texture by said piece of porous material so as to obtain a fibrous preform loaded with refractory particles.

By using a piece of porous material to drain the liquid from the slip, the method of the invention eliminates the liquid phase of the slip introduced into the fibrous texture without removing the refractory solid particles also present in the texture. The elimination of the liquid phase of the slurry by drainage also makes it possible not to disturb the distribution of the refractory particles within the fibrous texture and subsequently to obtain a composite material part with a high matrix volume ratio and having, therefore, improved mechanical properties.

According to a particular characteristic of the impregnation process of the invention, the fibrous texture is obtained by three-dimensional weaving or by needling of a plurality of fibrous layers.

According to one particular characteristic of the impregnation process of the invention, the impermeable membrane is made of silicone or EPDM (Ethylolene, Propylene, Diene and Monomer), each serving shaped being obtained by local forming of silicone or EPDM. Each shaped portion may further be stiffened by adding a glass or polyester fabric between two layers of silicone or EPDM, or by local stacking additional layers of silicone or EPDM so as to form a local extra thickness in the membrane.

The subject of the invention is also a process for manufacturing a composite material part comprising the following steps:

impregnation of a fibrous texture according to the impregnation method of the invention,

demolding of the impregnated fibrous preform, and

- Transforming the liquid composition to form a matrix in said preform.

- impregnation of a fibrous texture according to the impregnation method of the invention implementing a piece of porous material and a filled slip as defined above,

drying the fibrous preform,

demolding of the fibrous preform, and

sintering the refractory particles present in the fibrous preform in order to form a refractory matrix in said preform.

The present invention finally relates to an impregnation tool for a fibrous texture comprising:

a mold comprising an impregnation chamber comprising a bottom intended to receive a first face of a fibrous texture, the impregnation chamber being closed in its upper part by an impermeable membrane at least partly deformable and intended to be placed in looking at a second face of the fibrous texture, said membrane separating the impregnation chamber from a compaction chamber,

at least one first injection port opening into the impregnation chamber,

at least one second injection port opening into the compaction chamber, characterized in that the impermeable membrane comprises at least one shaped portion having a shape in relief relative to the plane of the membrane.

The impregnation tool of the invention makes it possible to ensure homogeneous impregnation of the or portions of excess thickness of a fibrous texture, and without deformation or appearance of folds at the level or the portions of excess thickness that may occur. produce when a simple flat membrane is forced to deform excessively at one or more portions of extra thickness.

In addition, the tooling of the invention can be used to impregnate fibrous textures having various shapes and dimensions at the level or portions of extra thickness, only the membrane being changed to fit the shape and dimensions texture to impregnate.

According to one embodiment of the impregnation tool of the invention, each shaped portion of the impermeable membrane has a stiffness greater than the other portions of said membrane.

Brief description of the drawings

Other characteristics and advantages of the invention will emerge from the following description of particular embodiments of the invention, given by way of non-limiting examples, with reference to the appended drawings, in which:

FIG. 1 is a schematic exploded sectional view of a tool according to an embodiment of the invention,

FIG. 2 is a diagrammatic sectional view showing the tool of FIG. 1 closed with a fibrous texture positioned therein,

FIGS. 3 and 4 are diagrammatic sectional views showing the steps of impregnating a fibrous texture with a liquid composition in the tool of FIG. 2 in accordance with one embodiment of the method of the invention, and

FIGS. 5 and 6 are diagrammatic sectional views showing the steps of impregnating a fibrous texture with a loaded slurry according to another embodiment of the method of the invention.

Detailed description of embodiments

The process for impregnating a fibrous texture according to the present invention begins with the production of a fibrous texture intended to form the reinforcement of the part.

The fibrous texture is made in known manner by weaving by means of a jacquard loom on which a bundle of warp yarns or strands has been arranged in a plurality of layers, the warp yarns being bound by yarns of frame or vice versa. The fibrous texture can be made by stacking strata or plies obtained by two-dimensional weaving (2D). The fibrous texture can also be produced directly in one piece by three-dimensional weaving (3D). By "two-dimensional weaving" is meant here a conventional weaving mode whereby each weft yarn passes from one side to another son of a single chain layer or vice versa. The method of the invention is particularly adapted to allow the introduction of a liquid composition in 2D fibrous textures (textures obtained by stacking layers or 2D folds) or 3D thick textures, that is to say fibrous structures having a thickness of at least 100 mm.

By "three-dimensional weaving" or "3D weaving" or "multilayer weaving" is meant here a weaving mode whereby at least some of the weft yarns bind warp yarns on several layers of warp yarns or conversely following a weave corresponding to a weave weave which can be chosen in particular from one of the following armor: interlock, multi-fabric, multi-satin and multi-twill.

By "weave or interlock fabric" is meant here a 3D weave armor, each layer of warp threads binding several layers of weft threads with all the threads of the same warp column having the same movement in the plane of the weave. armor.

By "armor or multi-fabric fabric" is meant here a 3D weave with several layers of weft son whose basic armor each layer is equivalent to a conventional canvas type armor but with some points of the weave that bind the layers of weft threads between them.

By "multi-satin weave or fabric" is meant here a 3D weave with several layers of weft yarns whose basic weave of each layer is equivalent to a classic satin-like weave but with certain points of the weave which bind the layers of weft threads together.

By "weave or multi-twill fabric" is meant here a 3D weave with several layers of weft threads whose basic armor of each layer is equivalent to a classic twill type armor but with some points of the armor that bind the layers of weft threads together.

3D textures have a complex geometry in which it is difficult to introduce and homogeneously distribute loaded or unloaded liquid compositions. The process of the invention is also very well suited for introducing a liquid composition into 3D woven fiber textures. The method of the invention also applies to the introduction of a liquid composition, for example a ceramic precursor, into needled textures formed for example by stacking uni or two-dimensional fibrous layers bonded together by needling.

The yarns used to weave the fibrous texture intended to form the fibrous reinforcement of the piece of composite material may in particular be formed of fibers consisting of one of the following materials: carbon, silicon carbide, glass, alumina, mullite, aluminosilicate, borosilicate, or a mixture of several of these materials.

Once the fibrous texture has been produced, it is placed in a tool according to the invention which makes it possible, as explained hereinafter, to impregnate the fibrous texture with a liquid composition. For this purpose and as illustrated in Figures 1 and 2, a fibrous texture 10 is placed in a tool 100. The fibrous texture 10 comprises, on its face 10a intended to be exposed in the mold, a portion of extra thickness 11 which forms a relief on said face of the texture. In the example described here, the fibrous texture 10 is produced according to one of the techniques defined above (stacking 2D layers or 3D weaving) with carbon threads. The Fibrous texture 10 is here intended to form the fibrous reinforcement of a piece of carbon / carbon (C / C) composite material.

The tooling 100 comprises a mold 110 whose bottom 111 is provided with a plurality of vents 112. The mold 110 also comprises a side wall 113 having an injection port 114 equipped with a valve 1140. The face 10b of the fibrous texture opposite its exposed face 10a is placed on the surface 111a of the bottom 111.

The tooling 100 further comprises a cover 130 comprising an injection port 131 equipped with a valve 1310 and an impermeable membrane 140 which, once the tool has been closed (FIG. 2), separates an impregnation chamber 101 in which is present the fibrous texture 10 of a compaction chamber 102 located above the membrane 140.

According to the invention, the membrane comprises one or more shaped portions each having a shape substantially corresponding to the portion or portions of extra thickness present on the exposed face of the fibrous texture in order to match these extra thicknesses during the injection of a fluid compaction as explained below in detail. In the example described here, the membrane 140 comprises a shaped portion 141 which has at rest a relief shape relative to the plane of the membrane 140 defined here by plane portions 142 and 143. The shaped portion 140 has a corresponding shape substantially to the shape of the contour of the portion of extra thickness 11 of the fibrous texture 10. The shaped portion 141 can be obtained by forming a flat membrane made of silicone or EPDM (Ethylolene, Propylene, Diene and Monomer).

According to an alternative embodiment, the shaped portion or portions of the membrane have a higher stiffness than the other portions of the membrane. In the example described here, the shaped portion 141 of the membrane 140 has a greater rigidity than the other portions 142 and 143 of the membrane 140. This ensures the shape of the shaped portion of the membrane during its handling and particularly during the injection of a fluid compaction as explained below. For this purpose, the membrane 140 may be made from a layer of a first impervious and deformable material such as silicone or EPDM, the shaped portion 141 being obtained by forming the silicone or EPDM. The shaped portion 141 may be stiffened by adding a glass or polyester fabric between two layers of silicone or EPDM, or by locally stacking additional layers of silicone or EPDM to create a local extra thickness in the membrane.

After placing the texture 10 in the impregnation chamber, the mold 110 is closed with the lid 130 (FIG. 2). A liquid composition 150 is then injected into the impregnation chamber 101 via the injection port 114, the valve 1140 of which is open (FIG. 3). The liquid composition 150 is, in this example, intended to allow the formation of a carbon matrix in the texture. The liquid composition 150 corresponds here to a phenolic resin.

The amount of liquid composition 150 injected into the impregnation chamber 101 is determined as a function of the volume of the fibrous texture to be impregnated.

Once the liquid composition has been injected into the impregnation chamber 101, the compaction operation is carried out by injecting a compression fluid 160, for example oil, into the compaction chamber 102 via the injection port 131. whose valve 1310 is open, the valve 1140 of the injection port 114 having been previously closed. The compression fluid 160 applies a pressure on the liquid composition 150 through the membrane 140 which forces the liquid composition 150 to penetrate into the fibrous texture 10 as illustrated in FIG. 4. The fluid 160 imposes a hydrostatic pressure on the entirety of the membrane 140 and, therefore, the entire liquid composition present above the texture 10, the membrane 140 deforming at its portions 142 and 143 to force the liquid composition to penetrate into the texture. The pressure applied by the membrane 140 on the liquid composition and on the fibrous texture is preferably less than 15 bar, for example 7 bar, so as to make the liquid composition penetrate the texture. The excess liquid composition is evacuated by the vents 112.

Thanks to the presence of the conformation portion 141 in the membrane 141, the thickening portion 11 of the fibrous texture 10 is impregnated homogeneously like the rest of the texture, and without deformation or appearance of folds at the portion of extra thickness 11 that can occur when constraining a simple membrane planar to deform excessively at the portion of this extra thickness.

A fibrous preform 20 impregnated with a matrix precursor is thus obtained, here a carbon matrix, which comprises a portion of extra thickness 21 corresponding to the portion of extra thickness 11 of the texture 10 (FIG. 4). The preform is then demolded by emptying the compression fluid of the compaction chamber 102, the preform retaining after demolding its compaction geometry.

The preform is then extracted from the tooling and subjected to a treatment making it possible to transform the liquid composition into a matrix of a given material. In the example described here, the impregnated fiber preform 20 is subjected to a heat treatment to carbonize the phenolic resin.

A piece of CMC composite material can be obtained in the same way by producing the fiber texture with silicon carbide or carbon fibers and by using a liquid composition containing a ceramic precursor such as a polycarbosilane resin (PCS) or polytitanocarbosilane (PTCS) or polysilazanes (PSZ) for obtaining silicon carbide (SiC) after heat treatment.

Similarly, a piece of CMO composite material can be obtained always in the same way by producing the fiber texture with fibers for example glass or carbon and using a liquid composition containing a precursor of organic material such as a polyester resin or a polyimide resin or a charged organic resin.

Figures 5 and 6 illustrate the impregnation of a fibrous texture for producing an oxide / oxide composite material. For this purpose and as illustrated in Figures 5 and 6, a fibrous texture 30 is placed in a tool 200. The fibrous texture 30 has, on its face 30a intended to be exposed in the mold, a portion of extra thickness 31 which forms a relief on said face of the texture. In the example described here, the fibrous texture 30 is made according to one of the techniques defined above (2D stack stacking or 3D weaving) with Nextel 610 ™ alumina threads. The fibrous texture 30 is here intended to form the fibrous reinforcement of a piece of oxide / oxide composite material. As for the tooling 100 already described, the tool 200 comprises a mold 210 whose bottom 211 is provided with a vent 212. The mold 210 also comprises a side wall 213 having an injection port 214 equipped with a valve 2140. A piece of porous material 220 is also placed on the inner surface 211a of the bottom 211. The piece of porous material 220 has a lower face 220b in contact with the inner surface 211a of the bottom 211 and an upper face 220a for to receive the fibrous texture 30. The piece 220 may for example be made of microporous polytetrafluoroethylene (PTFE) such as "microporous PTFE" products sold by the company Porex®.

For example, the piece of porous material may have a thickness of several millimeters and an average porosity of about 30%. The average pore size (D50) of the piece of porous material may for example be between 1 μm and 2 μm.

The tool 200 further comprises a cover 230 comprising an injection port 231 equipped with a valve 2310 and a partially deformable membrane 240 which, once the tool has been closed (FIG. 5), separates an impregnation chamber 201 wherein is present the fibrous texture 30 of a compaction chamber 202 located above the membrane 240.

According to the invention, the membrane comprises one or more shaped portions each having a shape substantially corresponding to the portion or portions of extra thickness present on the exposed face of the fibrous texture in order to match these extra thicknesses during the injection of a fluid compaction as explained below in detail. In the example described here, the membrane 240 comprises a shaped portion 241 which has at rest a relief shape relative to the plane of the membrane 240 defined here by planar portions 242 and 243. The shaped portion 240 has a corresponding shape substantially to the shape of the contour of the portion of extra thickness 31 of the fibrous texture. The shaped portion 241 may be obtained by forming a flat membrane made of silicone or EPDM.

According to an alternative embodiment, the shaped portion or portions of the membrane have a higher stiffness than the other portions of the membrane. In the example described here, the shaped portion 241 of the membrane 240 has a higher rigidity than the other portions 242 and 243 of the membrane 240. This ensures the shape of the shaped portion of the membrane during its handling and in particular during the injection of a compaction fluid as explained below. For this purpose, the membrane 240 may be made from a layer of a first impervious and deformable material such as silicone or EPDM, the shaped portion 241 being stiffened by the addition of a glass or polyester fabric between 2 Silicone or EPDM layers, or by local stacking of additional layers of silicone or EPDM to create a local extra thickness in the membrane.

As indicated above, the membrane used in the impregnation process of the invention may in particular be made from a silicone material reinforced with a glass or polyester fabric. In this case, several layers of unvulcanized silicone are draped over shaped tooling, a glass or polyester fabric being inserted locally between two layers of silicone to reinforce the membrane. The number of layers is adjusted according to the rigidity to obtain. Once the draping is complete, a vacuum cover is applied to the assembly and the assembly is placed in an oven for vulcanizing the silicone. Once the mold has cooled, the membrane in one piece can be demolded.

A material capable of being conformed may be chosen in particular from one of the following materials: carbon, silicon carbide, glass, alumina, mullite, aluminosilicate, borosilicate, or a mixture of several of these materials.

After placement of the texture 30 on the upper face 220a of the piece of porous material 220, the mold 210 is closed with the lid 230 (Figure 5). A slurry 250 is then injected into the impregnation chamber 201 via the injection port 214, the valve 2140 of which is open (FIG. 5). The slurry 250 is, in this example, intended to allow the formation of a refractory oxide matrix in the texture. The slurry 250 corresponds to a suspension containing a powder of refractory oxide particles, the particles having a mean particle size of between 0.1 μηι and 10 μηι. The liquid phase of the slurry may in particular consist of water (acidic pH), ethanol or any other liquid in which it is possible to suspend the desired powder. An organic binder can also be added (PVA for example, soluble in water). This binder ensures the holding of the raw material after drying and before sintering.

The slurry 250 may for example correspond to an aqueous suspension consisting of alumina powder whose average particle size (D50) is between 0.1 μm and 0.3 μm and whose volume fraction is between 27% and 42%. the suspension being acidified with nitric acid (pH between 1.5 and 4). In addition to alumina, the refractory oxide particles may also be of a material selected from mullite, silica, aluminosilicate, aluminophosphate and zirconia. Depending on their base composition, the refractory oxide particles can be further mixed with particles of alumina, zirconia, aluminosilicate, rare earth oxides, rare earth di-silicates (used by example in environmental or thermal barriers) or any other load allowing to add functions specific to the final material (carbon black, graphite, silicon carbide, etc.).

The amount of slurry 250 injected into the impregnation chamber 201 is determined as a function of the volume of the fibrous texture to be impregnated. It is the quantity of powder initially introduced which will control the thickness of setting and thus the volume ratio of fibers (Tvf) and matrix (Tvm).

Once the slip has been injected into the impregnation chamber 201, the compaction operation is carried out by injecting a compression fluid 260, for example oil, into the compaction chamber 202 through the injection port 231 of which the valve 2310 is open, the valve 2140 of the injection port 214 having been previously closed. The fluid 260 imposes a hydrostatic pressure on the entire membrane 240 and, consequently, on the entirety of the liquid composition present above the texture 30, the membrane 240 deforming at its portions 242 and 243 to force the liquid composition to penetrate the texture. The pressure applied by the membrane 240 on the slip and on the fibrous texture is preferably less than 15 bar, for example 7 bar, so as to penetrate the slip in the texture.

Thanks to the presence of the conformation portion 241 in the membrane 241, the thickening portion 31 of the fibrous texture 30 is impregnated homogeneously like the rest of the texture, and this without deformations or appearance of folds at the portion of thickening 31 that may occur when forced a simple flat membrane to deform excessively at the portion of extra thickness.

The porous material part 220 which is located on the side of the face 30b of the fibrous texture opposite the face 30a from which the slip penetrates the texture performs several functions. Indeed, the part 220 allows the liquid to be drained from the slip outside the fibrous texture, the liquid thus drained being evacuated here by the vent 212. The drainage is carried out both during and after the operation. compaction. When there is no more liquid flowing through the vent 212, drainage is complete. In combination with the application of a pressure on the slip by the compression fluid, a pumping P, for example by means of a primary vacuum pump (not shown in Figure 6), can be achieved at the level of vent 212. This pumping is optional. Heating can suffice. However, the combination of both speeds up drying.

In addition, the tool may be provided with heating means, such as resistive elements integrated into the walls of the tool, in order to increase the temperature in the compaction chamber and facilitate evacuation of the liquid from the slip by evaporation. The temperature in the compaction chamber can be raised to a temperature between 80 ° C and 105 ° C.

The porous material part 220 also makes it possible to retain the solid particles of refractory oxide present in the slip, the refractory oxide particles thus settling progressively by sedimentation in the fibrous texture. This makes it possible to obtain later (i.e. after sintering) the matrix.

The part 220 also makes it possible to maintain the fibrous texture in shape during the compaction operation because it resumes on its upper face 220a the shape of the bottom 211 of the mold 210 corresponding to the shape of the final piece to be manufactured.

A fibrous preform 40 is thus obtained, which is charged with refractory oxide particles, here particles of alumina of the type described above, which comprises a portion of extra thickness 41 corresponding to the portion of extra thickness 31 of the texture 30 (FIG. 6). The preform is then demolded by emptying the compression fluid of the compaction chamber 202, the preform retaining after demolding its compaction geometry.

The preform is then extracted from the tooling and subjected to an air sinter heat treatment at a temperature of between 1000 ° C. and 1200 ° C. in order to sinter the refractory oxide particles together and thus form a refractory oxide matrix in the preform. This gives a piece of oxide / oxide composite material provided with a fiber reinforcement obtained by 3D weaving which has a high matrix volume ratio with a homogeneous distribution of the matrix throughout the fibrous reinforcement.

A piece of CMC composite material can be obtained in the same way by producing the fibrous texture with silicon carbide or carbon fibers and using a slurry loaded with carbide carbide particles (eg SiC), boride (ex. TiB2) or nitride (eg Si3N4).

Claims

A process for impregnating a fibrous texture (10) comprising the steps of:

- placing a fibrous texture (10) in an impregnation chamber (101) of a mold (110), the impregnation chamber (101) being closed in its upper part by an impermeable membrane at least partly deformable (140) facing an exposed face (10a) of the fibrous texture (10), said membrane (140) separating the impregnation chamber (101) from a compaction chamber (102),

injecting a liquid composition (150) containing at least one precursor of a matrix material into the impregnation chamber between the exposed face (10a) of the fibrous texture (10) and the membrane (140),

injecting a compression fluid (160) into the compaction chamber (102), the fluid exerting pressure on the membrane (140) to force the liquid composition (150) to penetrate the fibrous texture (10) so as to obtaining a fibrous preform (20) impregnated with said liquid composition,

characterized in that the fibrous texture (10) has on its exposed face (10a) at least one thickened portion (11) and in that the impermeable membrane (140) comprises at least one shaped portion (141) having a corresponding shape in the shape of the contour of said at least one portion of extra thickness (11) present on the exposed face (10a) of the fibrous texture (10).

2. Method according to claim 1, characterized in that each shaped portion (141) of the impermeable membrane (140) has a stiffness greater than the other portions (142, 143) of said membrane.

3. Method according to claim 1 or 2, characterized in that the impregnation chamber (201) of the mold (210) comprises in its lower part a piece of porous material (220) on which the texture (30) rests and in the liquid composition injected into the impregnation chamber comprises a slip (250) containing a powder of refractory particles, the method further comprising draining the porous material piece (220) from the liquid of the slip passed through the fibrous texture (30) and retaining the refractory particle powder within said texture by said piece of porous material (220) so as to obtain a fibrous preform (40) loaded with refractory particles.

4. Method according to any one of claims 1 to 3, characterized in that the fibrous texture (10) is obtained by three-dimensional weaving or by needling a plurality of fibrous layers.

5. Method according to any one of claims 1 to 4, wherein the impermeable membrane (140) is made of silicone or EPDM (Ethylolene, Propylene, Diene and Monomer), each shaped portion (141) being obtained by local forming. silicone or EPDM.

The process according to any one of claims 2 to 4, wherein the impermeable membrane (140) is made from a plurality of stacked silicone or EPDM layers (Ethyolene, Propylene, Diene and Monomer), each shaped portion. (141) being obtained by locally forming the silicone or EPDM and wherein each shaped portion (141) is stiffened by adding a glass or polyester fabric between two layers of silicone or EPDM, or by local stacking of additional layers of silicone or EPDM so as to form a local extra thickness in the membrane.

7. A method of manufacturing a composite material part comprising the following steps:

impregnation of a fibrous texture (10) according to the impregnation method of any one of claims 1 to 2,

demolding the impregnated fibrous preform (20), and

- Transforming the liquid composition to form a matrix in said preform. 8. A method of manufacturing a composite material part comprising the following steps: impregnation of a fibrous texture (30) according to the impregnation method of claim 3 or 4,

drying the fiber preform (40),

demolding the fibrous preform (40), and

9. Impregnation tool for a fibrous texture (10) comprising:

a mold (110) comprising an impregnation chamber

(101) having a bottom for receiving a first face (10b) of a fibrous texture (10), the impregnation chamber (101) being closed in its upper part by an impermeable membrane at least partly deformable (140) and intended to be placed facing a second face (10a) of the fibrous texture (10), said membrane (140) separating the impregnation chamber (101) from a compaction chamber

(102),

at least one first injection port (114) opening into the impregnation chamber,

at least one second injection port (131) opening into the compaction chamber (102),

characterized in that the impermeable membrane (140) comprises at least one shaped portion (141) having a raised shape with respect to the plane of the membrane (140).

10. Tooling according to claim 9, characterized in that each shaped portion of the impermeable membrane has a rigidity greater than the other portions of said membrane.