Process for manufacturing a fibrous texture for densification by chemical infiltration in the gas phase
The method of three-dimensional weaving with carbon fiber insertion and controlled CVI densification addresses the issue of inconsistent porosity and properties in CMC materials by achieving uniform densification and porosity levels.
Patent Information
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- SAFRAN CERAMICS SA
- Filing Date
- 2024-05-13
- Publication Date
- 2026-05-22
AI Technical Summary
Existing methods for densifying fibrous textures in ceramic matrix composites (CMC) fail to achieve homogeneous porosity and local properties due to varying thicknesses, leading to inconsistent material characteristics.
A method involving three-dimensional weaving with carbon fiber yarns inserted in the core of thicker areas, allowing localized heating and controlled ceramic matrix deposition through chemical vapor infiltration (CVI), followed by selective removal of carbon fibers to enhance homogeneity.
Achieves uniform densification and porosity levels across fibrous textures, ensuring consistent material properties despite thickness variations.
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Abstract
Description
Title of the invention: Method for manufacturing a fibrous texture for densification by chemical infiltration in the gas phase. Technical field
[0001] The invention relates to the general field of manufacturing parts in ceramic matrix composite (CMC) material having a ceramic fiber reinforcement texture densified by a ceramic matrix. Previous technique
[0002] The invention relates more particularly to controlling the densification of a fibrous texture intended to form the fibrous reinforcement of a composite part when the densification is carried out at least partially by the well-known gas-phase chemical infiltration (CVI) densification process. According to the CVI densification process, the fibrous preform(s) to be densified are placed in a reaction chamber of an installation where they are heated. A reactive gas containing one or more gaseous precursors of the matrix material is introduced into the furnace. The temperature and pressure in the installation are adjusted to allow the reactive gas to diffuse within the porosity of the preforms and form a deposit of the matrix material by decomposition of one or more components of the reactive gas or by reaction between several components, this or these components forming the matrix precursor.
[0003] In some cases, the fibrous textures to be densified have highly variable thicknesses from one area to another, for example, by a factor of 1 to 5, or even 1 to 10. When the texture is densified by CVI, this results in areas with very different interphase and matrix thicknesses because a thick area is much more difficult to infiltrate than a thin one. This can impact the volumetric content of constituents, particularly the final porosity, and the local properties of the material thus produced. Therefore, there is a need to be able to densify a fibrous texture homogeneously despite different thicknesses so that the porosity level is similar from one area to another. Description of the invention
[0004] To this end, the present invention proposes a method for manufacturing a fibrous texture for a part made of ceramic matrix composite material, comprising the production of a fibrous blank, the fibrous blank comprising a woven portion produced by three-dimensional or multilayer weaving between a plurality of layers of warp yarns made of silicon carbide fibers and layers of weft yarns predominantly made of silicon carbide fibers, the woven portion comprising at least of the first and second parts, the first part having, in a direction perpendicular to the warp and weft directions, a thickness greater than the thickness of the second part, characterized in that it further comprises the following steps: - insertion, during the weaving of the fibrous blank, of carbon fiber yarns in one or more weft layers located in the core of the first part of the woven portion, - cutting of the warp yarns and weft yarns in silicon carbide fibers at the limit of the woven portion while retaining excess lengths of carbon fiber weft yarns on each side of the woven portion so as to obtain a fibrous texture comprising a preform corresponding to said woven portion and comprising non-woven parts of carbon fiber weft yarns extending on each side of the fibrous preform.
[0005] This gives a fibrous texture which can be heated locally to the core of a thicker part and thus allow better control of the deposition of a ceramic matrix by CVI.
[0006] According to a particular feature of the process of the invention, during the weaving of the fibrous blank, silicon carbide fiber braids comprising one or more carbon fiber core yarns are inserted into one or more weft layers located in the core of the first part of the woven portion. This advantageously limits any disturbances related to the use of carbon fibers in the fibrous texture by coating one or more carbon fiber yarns with a SiC fiber braid.
[0007] According to another particular feature of the process of the invention, the quantity of carbon fiber yarns inserted into the core of the first part of the woven portion is between 1% and 50% of the total weft yarns present in said first part of the woven portion. It is thus possible to define a local heating capacity of the texture as a function of the quantity of carbon yarns inserted, while maintaining at least half of the SiC fibers in the core.
[0008] According to another particular feature of the process of the invention, the first part of the woven portion has a thickness at least three times, or even five times, greater than the thickness of the second part of the woven portion.
[0009] The invention also relates to a method for manufacturing a part made of ceramic matrix composite material comprising the following steps:
[0010] - manufacturing a fibrous texture according to the manufacturing process of a fibrous texture according to the invention,
[0011] - first ceramic matrix deposition comprising heating of fiber wires of carbon present at the core in the first part of the woven portion of the fibrous texture at a temperature greater than or equal to a decomposition temperature of one or more gaseous ceramic matrix precursors, without any further heating of the fibrous texture being carried out, and bringing the fibrous texture into contact with the gaseous ceramic matrix precursor(s) so as to achieve the first deposition of ceramic matrix in the core of the first part of the woven portion of the fibrous texture,
[0012] - second ceramic matrix deposition comprising heating the assembly of the fibrous structure at a temperature greater than or equal to the decomposition temperature of one or more gaseous ceramic matrix precursors, and bringing the fibrous texture into contact with the gaseous matrix precursor(s) so as to carry out the second ceramic matrix deposition throughout the fibrous texture.
[0013] At the end of the second ceramic matrix deposition by CVI, the fibrous texture exhibits an overall homogeneous level of densification, despite the differences in thickness present within the texture. The texture thus exhibits a similar level of porosity throughout its volume.
[0014] According to a particular feature of the process of the invention, the heating of the carbon fiber yarns present at the core in the first part of the woven portion of the fibrous texture is achieved by circulating a direct current in said yarns.
[0015] According to another particular feature of the process of the invention, the carbon fiber yarns present in the core of the first part of the woven portion of the fibrous texture are removed before the heating step of the entire fibrous structure. Removing the carbon yarns after the first matrix deposition allows the formation of infiltration channels in the fibrous texture, which further improve the homogeneity of the deposition during the second matrix deposition by CVI.
[0016] According to another particular feature of the process of the invention, the first part of the woven portion of the fibrous texture corresponds to a preform foot part of a turbomachine blade and the second part of the woven portion of the fibrous texture corresponds to a preform blade part of a turbomachine blade.
[0017] The invention also relates to a fibrous texture for a part made of ceramic matrix composite material, the fibrous texture comprising a woven portion having a three-dimensional or multilayer weave between a plurality of layers of warp yarns made of silicon carbide fibers and layers of weft yarns predominantly made of silicon carbide fibers, the woven portion comprising at least first and second parts, the first part having, in a direction perpendicular to the warp and weft directions, a thickness greater than the thickness of the second part,
[0018] characterized in that it further comprises carbon fiber yarns in one or more weft layers located in the core of the first part of the woven portion and in that said carbon fiber yarns extend on each side of the first part of said woven portion along the weft direction.
[0019] The fibrous texture can thus be heated locally at the core of one of its thicker parts and thus allow better control of the deposition of a ceramic matrix by CVI.
[0020] According to a particular feature of the texture of the invention, it comprises silicon carbide fiber braids including one or more carbon fiber core yarns, the braids being present in one or more weft layers located in the core of the first part of the woven portion. This advantageously limits any disturbances related to the use of carbon fibers in the fibrous texture by coating one or more carbon fiber yarns with a SiC fiber braid.
[0021] According to another particular feature of the texture of the invention, the quantity of carbon fiber yarns inserted into the core of the first part of the woven portion is between 1% and 50% of the total weft yarns present in said first part of the woven portion. It is thus possible to define a local heating capacity of the texture as a function of the quantity of carbon yarns inserted, while maintaining at least half of the SiC fibers in the core.
[0022] According to another particular feature of the texture of the invention, the first part of the woven portion has a thickness at least three times, or even five times, greater than the thickness of the second part of the woven portion. Brief description of the drawings
[0023] [Fig-1] Fig. 1 is a schematic perspective view of a loom showing the three-dimensional weaving of a fibrous texture,
[0024] [Fig.2] Fig.2 illustrates in a very schematic way a woven fibrous blank three-dimensional device for creating a fibrous texture according to one embodiment of the invention,
[0025] [Fig.3] Fig.3 is a schematic view of a fibrous texture obtained from the fibrous blank of [Fig.2] according to one embodiment of the invention,
[0026] [Fig.4] Fig.4 is a schematic view of a carbide fiber braid silicon with carbon fiber core wires,
[0027] [Fig. 5] Fig. 5 is a schematic cross-sectional view of a treatment plant by chemical infiltration in the gas phase used to achieve a local matrix deposition at the core of the fibrous texture of [Fig.3] according to a process according to the invention,
[0028] [Fig.6] Fig.6 is a schematic cross-sectional view of a treatment plant by chemical infiltration in the gas phase used to perform matrix deposition in the whole fibrous texture of the [Fig.3] according to a process according to the invention. Description of the implementation methods
[0029] The invention applies generally to all fibrous textures formed by three-dimensional or multilayer weaving that comprise parts of different thicknesses and that are intended to be at least partially densified by chemical infiltration in the gas phase or CVI of a ceramic matrix. The fibrous texture of the invention is intended to constitute a fibrous reinforcement, or a preform, for the manufacture of a part made of ceramic matrix composite or CMC material, in particular aircraft engine blades. The invention therefore also applies to the manufacture of parts made of CMC material such as SiC / SiC, SiC / SiBC, or SiC / SiC-SiBC.
[0030] By "three-dimensional weaving" or "3D weaving", we mean here a weaving method in which at least some of the warp yarns bind weft yarns over several weft layers.
[0031] By "multilayer weave" is meant here a 3D weave with several layers of weft, the basic weave of each layer being equivalent to a classic 2D fabric weave, such as a plain weave, satin or twill weave, but with certain points of the weave which link the weft layers together.
[0032] The creation of the fibrous structure by 3D or multilayer weaving allows for bonding between the layers, thus ensuring good mechanical strength of both the fibrous structure and the resulting composite part, all in a single textile operation. A detailed example of the creation of a fibrous preform intended to form the fibrous reinforcement of an aircraft engine blade is described in detail in US documents 7,101,154, US 7,241,112, and WO 2010 / 061140.
[0033] An example of manufacturing a fibrous texture is now described in accordance with an example of an embodiment of the process for manufacturing a fibrous texture of the invention in which the fibrous texture is intended to form a fibrous reinforcement of a CMC turbomachine blade.
[0034] Figure 1 illustrates a loom 100 used to produce a fibrous blank 20 according to an embodiment of the invention. The loom 100 is equipped with a Jacquard mechanism 101 supported by a superstructure not shown in Figure 1. The loom 100 also includes a harness 110 consisting of a heddle board 111 and control threads or heddles 113, each heddle 113 being connected at one end to a control hook 1010 of the Jacquard mechanism 101 and at the other end to one of the return springs 102 fixed to the frame 103 of the loom 100. Each heddle 113 includes an eyelet 114 through which a warp thread 201 passes. The warp yarns 201 are arranged in a plurality of warp yarn layers Ci to Cn. The heddles 113 and their associated eyelets 114 are animated by a substantially vertical oscillating motion represented by the double arrow F. The heddles 113 allow certain warp yarns 201 to be lifted according to a defined weaving program. By lifting certain warp yarns 201, the heddles 113 thus create a swarm that allows the introduction of weft yarns 202 for the 3D or multilayer weaving of fibrous structures. It is therefore possible to insert, during weaving, weft yarns of different types into the fibrous blank 20, as explained in detail below.
[0035] Figure 2 schematically illustrates the fiber blank 20 obtained from the loom 100. The fiber blank 20 comprises a woven mass or portion 200 having a three-dimensional or multilayer weave between warp yarns 201 arranged in a plurality of layers and weft yarns 202 also arranged in a plurality of layers. The woven portion 200 is surrounded within the fiber blank 20 by the non-woven portions of the warp yarns 201 and the weft yarns 202, which are called "fringes." The warp yarns 201 are made of silicon carbide (SiC) fibers, while the weft yarns are predominantly made of SiC fibers, a fraction of the weft yarns being or comprising carbon fiber yarns at specific locations within the woven portion 200 according to the invention.For SiC warp and weft yarns, one can use, for example, SiC fiber yarns such as those marketed by the Japanese company Nippon Carbon under the name "Hi-Nicalon S".
[0036] The fibrous blank 20 is woven as a strip extending generally in a direction Dc corresponding to the direction of the warp yarns 201 and the longitudinal direction of the blade to be produced, the weft yarns 202 extending in a direction DT perpendicular to the direction Dc. In the fibrous blank 20, the woven portion 200 includes, in the direction Dc, a thickened section 210 intended to form the root of the blade to be produced, which is extended by a section 220 intended to form the blade of the blade. The woven portion 200 is woven in one piece and comprises a first part, here the thickened section 210, which has a thickness E210 greater than the thickness E220 of a second part in the warp direction Dc, here the section 220.
[0037] According to the invention, carbon fiber yarns, in the example described here from TC1 to TC7 yarns, are inserted during the weaving of the fiber blank 20 into one or more layers of weft yarns 202 located in the core of the woven portion of the fiber blank, here the thicker portion 210, which has a greater thickness than the other or other adjacent portions of the woven portion, here portion 220. In the example described here and as illustrated in [Fig. 2], the fiber blank 20 comprises weft yarns 202 made mostly of SiC fibers except in the core of the portion 210 extra thickness of the woven portion 200 which includes TCi to TC7 carbon fiber yarns.
[0038] Once the fiber blank 20 has been woven, the fringes of the SiC fiber yarns are trimmed, i.e., the unwoven ends of the SiC fiber warp and weft yarns located outside the woven portion 200 (the so-called "trimming" phase). Figure 3 shows the woven portion 200 once extracted from the fiber blank, i.e., after the fringes of the SiC fiber yarns have been trimmed. The woven portion then has the almost final shape and dimensions of the blade ("net shape").
[0039] According to the invention, the carbon fiber yarns TCi to TC7 are not cut at the boundary of the woven portion so as to retain excess lengths of these yarns on each side of the thicker portion 210 of the woven portion. As illustrated in [Fig. 3], this results in a fibrous texture 300 comprising a preform 310 corresponding to the woven portion 200, the fibrous texture 300 having non-woven portions of weft yarns made of carbon fibers TCi to TC7 extending on each side of the fibrous preform.
[0040] During the weaving of the fiber blank, carbon fiber yarns can be directly inserted into the blank in place of certain SiC fiber yarns, such as the Tc i to TC7 carbon fiber yarns described previously. According to a particular feature of the invention, the carbon fiber yarns can be contained within SiC fiber braids that are inserted during the weaving of the fiber blank. Figure 4 illustrates an example of a T braid that can be used to insert carbon yarns into the fiber blank. The T braid of Figure 4 is formed from FS1C SiC fiber yarns, for example, from six to twelve SiC fiber yarns, resulting in a tubular SiC structure with a larger diameter than a standard yarn. The braid further comprises one or more Fc carbon fiber core yarns.Coating one or more carbon fiber strands with a SiC fiber braid helps limit potential disturbances related to the use of carbon fibers in the fiber structure, such as the deposition of carbon residues on the surrounding SiC fibers, which can disrupt the adhesion between the fibers and the matrix. In the case of localized heating of the carbon fiber strands by Joule heating, electrodes can be directly connected to the excess lengths of the SiC fiber braids. The electrical current transmitted by the electrodes will flow preferentially through the carbon fiber core strand(s) because they are more conductive than the SiC fibers.It can also be envisaged, when cutting the fringes, that only the parts of the SiC braids extending beyond the woven portion are cut in such a way as to retain excess lengths of the carbon fiber core yarns on each side of the thicker part of the woven portion.
[0041] The quantity of carbon yarns inserted into the core of the thicker part of the woven portion is between 1% and 50% of the total weft yarns present in said thicker part of the woven portion, preferably between 5% and 20%.
[0042] By way of non-limiting example, the thicker part of the woven portion has a thickness at least three, or even five or ten, times greater than the thickness of the other parts of the woven portion.
[0043] An example of manufacturing a part in CMC composite material is now described in accordance with an example of an embodiment of the manufacturing process of a part in CMC of the invention, in which the part is manufactured from the fibrous texture 300 described previously, the part to be produced here being a turbomachine blade in CMC.
[0044] After the realization of the fibrous texture 300, the manufacturing process includes the realization of a first deposit of ceramic matrix in the core of the overthickness part 210 of the woven portion 200 of the fibrous texture by chemical infiltration in gas phase (CVI) as shown in [Fig.5].
[0045] CVI treatment is a well-known process for densifying fibrous preforms to produce parts made of CMC composite material. The preform(s) to be densified are placed in a reaction chamber of a CVI installation. A reactive gas containing one or more gaseous precursors of the matrix material is introduced into the reaction chamber. The temperature and pressure are adjusted to allow the reactive gas to diffuse within the porosity of the preforms and form a deposit of the matrix material by decomposition of one or more components of the reactive gas or by reaction between several components, these components forming the matrix precursor. The process is carried out under reduced pressure to promote the diffusion of the reactive gases within the preforms.The transformation temperature of the precursor(s) to form the matrix material, such as a carbide, is in most cases between 900°C and 1200°C. For example, such a process is described in US patent 9,845,534.
[0046] In the case of the first core ceramic matrix deposition in the raised portion 210 of the woven portion 200 of the fibrous texture, the fibrous texture is heated locally at the raised portion, with no further heating of the fibrous texture occurring during this step. More specifically, as illustrated in [Fig. 5], the fibrous texture 300 is placed in a gas-phase chemical infiltration treatment (CVI) installation or furnace 400 delimited by an enclosure 410 that does not include heating means (cold-walled enclosure). The CVI treatment installation 400 includes a gas inlet 401 at one end of the installation, a reaction chamber 420, and a gas outlet 430 at a second end of the installation opposite to the first end. The gas inlet 401 includes a port 402 connected to a reactive gas line 440. The gas outlet 430 includes a port 431 connected to a vent line 460. The CVI treatment plant may of course include several gas inlets and / or gas outlets.
[0047] In the example described here, only one fibrous texture 300 is present in the reaction chamber 420 of the installation. However, it is known that several fibrous textures can be placed in the reaction chamber.
[0048] The CVI 400 treatment installation further includes a local heating system comprising a first electrode 471 connected to the carbon fiber wires TCi to TC7 protruding from one side of the fibrous texture 300, a second electrode 472 connected to the carbon fiber wires TCi to TC7 protruding from the other side of the fibrous texture 300, and a DC generator 473 connected to the first and second electrodes 471 and 472. The DC generator 473, the electrodes 471, 472, and the carbon fiber wires TCi to TC7 thus together form a closed electrical circuit in which a DC current I, delivered by the generator 473, can flow. The carbon wires TCi to TC7 subjected to the current I produce heat by Joule heating.The intensity of the current I delivered by the generator 473 is set so as to heat the carbon wires connected to the electrodes to a determined temperature greater than or equal to a decomposition temperature of the gaseous ceramic matrix precursor(s) used for the first core matrix deposition in the overthickness part 210.
[0049] Local heating by carbon fiber wires can also be achieved by induction. In this case, the ends of each carbon wire protruding from both sides of the fibrous texture are connected together to form a closed loop capable of heating up when immersed in a varying electromagnetic field. According to another embodiment, one end of the carbon fiber wires can be directly connected to a heat source, the heat then being transferred into the core of the thicker portion 210 by thermal conduction.
[0050] Once the determined temperature is reached in the thickened section 210, a gas stream 11, containing one or more gaseous ceramic matrix precursors, for example monomethylsilane (MMS) or methyltrichlorosilane (MTS) yielding SiC by decomposition, is admitted into the reaction chamber 420 through the reactive gas line 440 and the injection port 402. The gas stream 11 flows through the reaction chamber 420 from the gas inlet 401 to the gas outlet 430. The by-products 12 resulting from the decomposition of the gas stream 10 are discharged at the gas outlet 430 through the discharge line 460.
[0051] The TCi to TC7 carbon fibers present in the core of the thickened section 210 will locally heat this section to a temperature that allows matrix deposition without heating the other, thinner sections of the fibrous structure 300, or at a temperature well below that which allows matrix deposition by decomposition. A first ceramic matrix deposition, for example of SiC, is thus carried out only in the core of the thickened section 230 of the fibrous structure 300. The CVI treatment temperature imposed in the thickened section 210 and the circulation of the gas flow 11 in the reaction chamber 120 are maintained for a predetermined duration corresponding to the level of CVI densification that is to be achieved in the thickened section 210, this duration being generally calculated according to the deposition kinetics and a target porosity level.
[0052] The ceramic matrix of the first deposit may, in particular, correspond to a silicon carbide (SiC) matrix, a Si-BC ternary system (SiBC), or a combination of the two (SiC / SiBC). For the deposition of an SiC matrix by CVI, monomethylsilane (MMS), as previously mentioned, can be used, yielding SiC by decomposition. For the deposition of an SiBC phase by CVI, the gas phase consists of a mixture of precursors of the elements Si, B, and C, to which a reducing element such as hydrogen (H2) is added. The elements carbon and silicon can be generated by precursors belonging respectively to the hydrocarbon and silane or chlorosilane families. The element boron is generated by a borane or a halide, such as boron trichloride (BC13).
[0053] Once the first ceramic matrix deposition has been carried out in the core of the overthickness part 210 of the fibrous texture 300, the manufacturing process includes carrying out a second ceramic matrix deposition in the whole of the fibrous texture 300 by CVI.
[0054] For this purpose, and as shown in [Fig. 6], the fibrous texture 300 is placed in a CVI processing installation or furnace 500 delimited by an enclosure 510 comprising a cylindrical side wall 511, a bottom wall 512, and a top wall 513. The CVI processing installation 500 includes a gas inlet 501 located at a first end of the installation, a preheating chamber 550, a reaction chamber 520, and a gas outlet 530. The gas inlet 501 includes a port 502 connected to a reactive gas line 540. The preheating chamber 550 includes several multi-perforated trays 551, 552, and 553 and is located between the gas inlet 501 and a first end 521 of the reaction chamber 520. The gas outlet 530 is located at a second end 522 of the installation opposite the first end. The CVI treatment installation may, of course, include several gas inlets.In the example described here, the 530 gas exhaust outlet includes a gas phase depletion module. comprising vents 531 connected to a gas exhaust pipe (not shown in [Fig.6]) connected to the enclosure 510 of the installation.
[0055] Still in the example described here, only one fibrous texture 300 is present in the reaction chamber 520 of the installation. However, it is known that it is possible to place several fibrous textures in the reaction chamber.
[0056] The CVI 500 processing unit also includes heating means. In the example described here, the unit is heated by induction. More specifically, the cylindrical side wall 511 of the enclosure 510 includes an armature, or susceptor 5110, for example made of graphite, which is coupled to an inductor 5112 located outside the unit and consisting of at least one induction coil. An insulator 5111 is interposed between the inductor 5112 and the susceptor 5110. As is well known, the CVI 500 processing unit is heated by warming the susceptor 5110 when the inductor 5112 is supplied with an alternating voltage. For this purpose, the inductor coil(s) are connected to an alternating voltage generator (not shown).The magnetic field created by the inductor 5112 induces an electric current in the susceptor 5110 which, through Joule heating, heats the susceptor, with the fibrous texture(s) inside the enclosure 510 being heated by radiation.
[0057] The heating of the CVI 500 treatment installation can be provided by other means such as electric heating means consisting for example of heating resistors embedded in the side wall of the enclosure.
[0058] A gas stream 31, containing a gaseous carbide precursor, for example monomethylsilane (MMS) or methyltrichlorosilane (MTS), yielding SiC by decomposition, is admitted into the reaction chamber 520 through the reactive gas line 540 and the injection port 502. The gas stream 31 is preheated during its circulation in the preheating chamber 550 before being introduced into the reaction chamber 520. The gas stream 31 flows through the fibrous texture 300 present in the reaction chamber from the preheating chamber 510 to the gas outlet 530. The by-products 32 resulting from the decomposition of the gas stream 31 are discharged through the gas outlet 530. A SiC matrix is deposited in the porosity of the fibrous texture 300 by decomposition of the gas stream 31.The CVI treatment temperature and the gas flow circulation 31 imposed in the reaction chamber 520 are maintained for a determined duration corresponding to the level of CVI densification that one wishes to achieve in the fibrous texture 300, this duration being generally calculated as a function of the deposition kinetics and a target porosity rate.
[0059] The ceramic matrix of the second deposit may in particular correspond to a silicon carbide (SiC) matrix, a Si-BC ternary system (SiBC), or a combination of the two (SiC / SiBC).
[0060] At the end of the second ceramic matrix deposition by CVI, the fibrous texture 300 exhibits an overall homogeneous level of densification, despite the differences in thickness present within the texture. The texture thus exhibits a similar level of porosity throughout its volume.
[0061] In the example described above, the first and second ceramic matrix depositions are carried out in different CVI processing facilities. However, the first and second ceramic matrix depositions can be carried out consecutively in the same CVI processing facility, such as in facility 500 of [Fig. 6], which will have been equipped with the local heating system of facility [Fig. 5], the heating means of facility 500 not being used during the first ceramic matrix deposition in the thick part of the fibrous texture.
[0062] After the initial localized deposition of the ceramic matrix within the fibrous structure, the carbon fiber(s) are at least cut at the boundary of the woven portion so as to completely match the fibrous structure to the fibrous preform of the part to be manufactured. According to a particular feature of the process of the invention, the carbon fibers can be removed from the fibrous structure, for example by controlled oxidation, after the initial matrix deposition in order to form infiltration channels within the fibrous structure. These channels will further improve the homogeneity of the deposition during the second matrix deposition by CVI.
[0063] The first and second ceramic matrix deposits can correspond to a partial or complete densification of the fibrous texture. In the case of partial densification, the first and second deposits can correspond to a consolidation phase of the fibrous texture, the densification of which is continued, for example, by injecting a ceramic powder slurry into the consolidated fibrous texture ("Slurry Cast" or "Slurry Transfer Molding") followed by infiltration of the texture with a molten silicon-based composition in order to fill the porosity still present in the preform, a densification process known as the MI process ("Melt Infiltration").
Claims
Demands
1. A method for manufacturing a fibrous texture (300) for a ceramic matrix composite part comprising the production of a fibrous blank (20), the fibrous blank comprising a woven portion (200) produced by three-dimensional or multilayer weaving between a plurality of layers of warp yarns (201) made of silicon carbide fibers and layers of weft yarns (202) predominantly made of silicon carbide fibers, the woven portion (200) comprising at least first and second parts (210, 220), the first part (210) having, in a direction perpendicular to the warp and weft directions (Dc, DT), a thickness (E2i0) greater than the thickness (E22o) of the second part (220), characterized in that it further comprises the following steps: - insertion, during the weaving of the fibrous blank (20),of carbon fiber yarns (Tci-Tc?) in one or more weft layers located in the core of the first part (210) of the woven portion (200), - cutting of the warp yarns (201) and weft yarns (202) of silicon carbide fibers at the boundary of the woven portion (200) while retaining excess lengths of carbon fiber weft yarns on each side of the woven portion so as to obtain a fibrous texture (300) comprising a preform corresponding to said woven portion (200) and comprising non-woven portions of carbon fiber weft yarns extending on each side of the fibrous preform.
2. A method according to claim 1, wherein, during the weaving of the fibrous blank (20), braids of silicon carbide fibers (T) comprising one or more core yarns of carbon fibers (Fc) are inserted into one or more weft layers located in the core of the first part (210) of the woven portion (200).
3. A method according to claim 1 or 2, wherein the quantity of carbon fibre yarns inserted core into the first part (210) of the woven portion (200) is between 1% and 50% of the total weft yarns present in said first part of the woven portion.
4. A method according to any one of claims 1 to 3, wherein the first part (210) of the woven portion (200) has a thickness (E2i0) at least three times greater than the thickness (E22o) of the second part (220) of the woven portion.
5. A method for manufacturing a part made of a ceramic matrix composite material comprising the following steps: - manufacturing a fibrous texture (300) according to the method according to any one of claims 1 to 4, - first ceramic matrix deposition comprising heating the carbon fiber yarns (TC1-TC7) present in the core of the first part (210) of the woven portion (200) of the fibrous texture (300) to a temperature greater than or equal to the decomposition temperature of one or more gaseous ceramic matrix precursors, no further heating of the fibrous texture being carried out, and bringing the fibrous texture (300) into contact with the gaseous ceramic matrix precursor(s) so as to effect the first ceramic matrix deposition in the core of the first part of the woven portion of the fibrous texture,- second ceramic matrix deposition comprising heating the entire fibrous structure (300) to a temperature greater than or equal to the decomposition temperature of one or more gaseous ceramic matrix precursors, and bringing the fibrous texture (300) into contact with the gaseous matrix precursor(s) so as to effect the second ceramic matrix deposition throughout the entire fibrous texture.
6. A method according to claim 5, wherein the heating of the carbon fiber yarns (Tci-Tc?) present at the core in the first part (210) of the woven portion (200) of the fibrous texture (300) is carried out by circulating a direct current (I) in said carbon fiber yarns.
7. A method according to claim 5 or 6, wherein the carbon fiber yarns (TCrTC7) present at the core in the first part (210) of the woven portion (200) of the fibrous texture (300) are removed before the heating step of the entire fibrous structure.
8. A method according to any one of claims 5 to 7, wherein the first part of the woven portion of the fibrous texture corresponds to a preform foot portion of a turbomachine blade and wherein the second part of the woven portion of the fibrous texture corresponds to a preform blade portion of a turbomachine blade.
9. Fibrous texture (300) for a ceramic matrix composite material part, the fibrous texture comprising a woven portion (200) having a three-dimensional or multilayer weave between a plurality of layers of warp yarns (201) of silicon carbide fibers and layers of weft yarns (202) predominantly of silicon carbide fibers, the woven portion (200) comprising at least first and second parts (210, 220), the first part (210) having, in a direction perpendicular to the warp and weft directions (Dc, DT), a thickness (E2i0) greater than the thickness (E220) of the second part (220),characterized in that it further comprises carbon fiber yarns (TCi-TC7) in one or more weft layers located in the core of the first part (210) of the woven portion (200) and in that said carbon fiber yarns extend on each side of the first part (210) of said woven portion (200) along the weft direction (DT).
10. Texture according to claim 9, comprising braids of silicon carbide (T) fibers comprising one or more core yarns of carbon fibers (FC), the braids being present in one or more weft layers located in the core of the first part (210) of the woven portion (200).
11. Texture according to claim 9 or 10, wherein the quantity of carbon fibre yarns inserted core in the first part (210) of the woven portion (200) is between 1% and 50% of the total weft yarns present in said first part of the woven portion.
12. Texture according to any one of claims 9 to 11, wherein the first part (210) of the woven portion (200) has a thickness (E2i0) at least three times greater than the thickness (E220) of the second part (220) of the woven portion.