METHOD FOR MANUFACTURING A CERAMIC MATRIX COMPOSITE PART FOR THE AERONAUTICAL INDUSTRY
By incorporating ceramic fillers with a polymeric binder to separate filaments and removing the binder partially, the method addresses the challenge of non-homogeneous matrix formation in ceramic matrix composites, achieving improved gas infiltration and matrix homogeneity.
Patent Information
- Authority / Receiving Office
- FR · FR
- Patent Type
- Applications
- Current Assignee / Owner
- SAFRAN CERAMICS SA
- Filing Date
- 2024-11-28
- Publication Date
- 2026-05-29
AI Technical Summary
Existing methods for manufacturing ceramic matrix composites face challenges in filling the intra-wire and inter-wire pores due to the cohesive nature of 3D woven ceramic fiber structures, which limits gas infiltration and results in non-homogeneous matrix formation.
A method involving the use of ceramic fillers intercalated between filaments with a polymeric binder to maintain separation during reinforcement preparation, followed by partial removal of the binder to create larger micropores, facilitating optimal gas infiltration and matrix formation.
The method ensures better gas infiltration and homogeneous matrix formation by creating larger micropores, enhancing the integrity and homogeneity of the ceramic matrix composite parts.
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Abstract
Description
Title of the invention: METHOD FOR MANUFACTURING A COMPOSITE MATRIX PART CERAMICS FOR THE AERONAUTICAL INDUSTRY Technical field of the invention
[0001] The invention relates to a method for manufacturing a ceramic matrix composite part, in particular for the aeronautical industry, the composite part comprising a ceramic reinforcement embedded in a ceramic matrix. Technical background
[0002] One field of application of the invention is the production of structural parts in thermostructural composite materials in particular with three-dimensional (3D) woven ceramic fiber reinforcement and ceramic matrix.
[0003] The consolidation and densification of a fibrous reinforcement structure by the constituent material of the matrix can be achieved by chemical vapor infiltration (or CVI - acronym for Chemical Vapor Infiltration), potentially followed by the STM (Slurry Transfer Molding) and MI (Melting Infiltration) processes.
[0004] The weaving of 3D reinforcing fibrous structures allowing gas infiltration is known, in particular on interlock, multi-satin, multi-twill and multi-fabric type armors.
[0005] The 3D armor used allows for varying degrees of gas infiltration. The structure of the filaments within the wires is quite cohesive, particularly on the surface, and includes intrawire porosities that are difficult to fill by gas infiltration, as access of gas to the core of the wires is limited by surface cohesion.
[0006] In order to homogenize the intra-wire spaces, it is advantageous to be able to separate the filaments from each other over the entire cross-section of a wire, and to maintain this separation throughout the upstream processes, namely wrapping, weaving, surface treatments, cutting and forming.
[0007] To achieve this opening by separating the filaments from one another, it would be possible to add fillers to the fibers or to a fabric made from these filaments. However, depending on the nature of these fillers, they could be easily removed during the early stages of the composite manufacturing process. Furthermore, these fillers could detach from the filaments during the process. Finally, the solution of using an electric field to insert fillers into a fabric is not applicable to ceramic fibers such as SiC fibers because the fabric behaves like a Faraday cage, preventing any separation of the fibers.
[0008] The present invention proposes a solution to this problem, which is simple, effective and economical. Summary of the invention
[0009] To this end, the invention proposes a method for manufacturing a composite part, particularly for the aeronautical industry, the composite part comprising a ceramic reinforcement embedded in a ceramic matrix, the method comprising the following steps:
[0010] a) preparation of the ceramic reinforcement, this ceramic reinforcement being porous and being formed by wires which define macropores between them, each of the wires being formed of a plurality of filaments which define micropores between them, the macropores and micropores being called pores,
[0011] b) gaseous infiltration of the ceramic reinforcement so as to at least partially fill said pores and to form said ceramic matrix,
[0012] characterized in that, during step a), the ceramic reinforcement is prepared with wires which comprise, in addition to filaments, ceramic fillers and a polymeric binder which ensures the retention of the fillers and filaments, the fillers being intercalated between the filaments so as to keep them apart from each other,
[0013] and in that the process includes, between steps a) and b), a step i) of removing at least part of the binder from the wires, the filaments remaining separated from each other by the charges.
[0014] The invention thus proposes to separate the filaments of the wires constituting the ceramic reinforcement, before its infiltration, by means of ceramic fillers that are bonded to the filaments during the preparation of the reinforcement. The fillers are bonded to the filaments by means of the binder that coats the filaments and forms, in particular, a sheath around each of the wires. It is therefore understood that the filaments are embedded in the binder, which holds the filaments together but, more importantly, holds the ceramic fillers that are inserted between the filaments so as to separate them from one another. The binder thus reduces the risk of loss of the fillers during the process. The nature of the fillers, being ceramic, is also chosen so that they can withstand the preparation stage of the reinforcement.
[0015] The presence of the fillers thus makes it possible to move the filaments further apart from each other during the preparation of the reinforcement.
[0016] Before the gas infiltration step, the binder is at least partially removed to empty the spaces between the filaments and the fillers, thus forming the aforementioned micropores. Due to the presence of the fillers between the filaments and the fact that the fillers will remain between the filaments, the micropores will have an average size larger than that obtained in the prior art.
[0017] Gas infiltration of the ceramic reinforcement will be all the easier and optimal to the extent that the reinforcement wires are more open with larger micropores.
[0018] The method according to the invention may comprise one or more of the following features, taken individually or in combination with each other: - the ceramic reinforcement is prepared in step a) by additive manufacturing. - the ceramic reinforcement is prepared in step a) by weaving, in particular in three dimensions. - filaments are fibers, particularly made of SiC; - The polymeric binder is a binder soluble in a solvent or comprises a solvent-soluble polymer, the removal of the binder in step i) being carried out by solubilizing the polymeric binder or its soluble polymer with said solvent; - the polymeric binder or its polymer is organic; - the polymeric binder or its polymer is chosen from among the polysaccharides, protein-based polymers, gelatins, casein, polyvinylpyrrolidone, polyethylene glycol and polyvinyl alcohol; - the solvent is water; - the polymeric binder is a thermally degradable binder or comprises a thermally degradable polymer, the removal of the sheath in step i) being carried out by heat treatment;
[0019] — the polymeric binder or its polymer is chosen from TPU, TPE, TPC, ABS, PC, PLA, PET, PA6, PEEK and PP; - the ceramic fillers are chosen from SiC, BN and Si3N4; - during step a), the wires are prepared by pultrusion, and in particular by impregnation pultrusion; - during step a), the fillers are mixed with the binder and then the binder with the fillers impregnates the wires; - the binder is photosensitive and is solidified in step a) by UV treatment in order to cause its polymerization;
[0020] — the polymeric binder comprises functional groups selected from the diazo, azide, cinnamic, furanic, acrylate and epoxide groups, or comprises a polymer including functional groups selected from diazo, azide, cinnamic, furanic, acrylate and epoxide groups; - the rate of ceramic fillers in the binder is between 1 and 10% by volume; - the ceramic fillers have a diameter D50 between 2 and 1 Opm. Brief description of the figures
[0021] Other features and advantages will become apparent from the following description of a non-limiting embodiment of the invention with reference to the accompanying drawings in which:
[0022] [Fig-1] [Fig. 1] is a schematic perspective view of a ceramic reinforcement before gaseous infiltration,
[0023] [Fig. 2a-2b] Figures 2a and 2b are schematic cross-sectional views of a wire used for the preparation of a ceramic reinforcement according to the previous technique, and represent this wire respectively before and after gas infiltration,
[0024] [Fig.3] [Fig.3] schematically represents the preparation of a thread in the frame of a method according to the invention,
[0025] [Fig.4] [Fig.4] is a schematic cross-sectional view of a wire used for the preparation of a ceramic reinforcement according to the invention,
[0026] [Fig.5] [Fig.5] is a very schematic view of a first installation of manufacturing of a thread used in the invention,
[0027] [Fig.6] [Fig.6] is a very schematic view of a second installation of manufacturing a thread used in the invention, and
[0028] [Fig. 7a-7b] Figures 7a and 7b are schematic cross-sectional views of a wire used for the preparation of a ceramic reinforcement according to the invention, and represent this wire respectively before and after gas infiltration. Detailed description of the invention
[0029] The present invention relates to a method for manufacturing a composite part, particularly for the aeronautical industry. The part is, for example, a turbomachine component, such as a blade, distributor, or ring.
[0030] The composite part comprises a fibrous reinforcement 10 embedded in a ceramic matrix 11.
[0031] Fig. 1 shows an example of ceramic reinforcement 10.
[0032] The ceramic reinforcement 10 is porous and is formed by wires 12 which define between macropores 14. Furthermore, each of the wires 12 is formed of a plurality of filaments 13 which define micropores 15 between them, the macropores 14 and micropores 15 being called pores 14, 15 in the context of the present invention.
[0033] Figures 2a and 2b illustrate a cross-section of a filament 13. The filaments 13 are, for example, SiC fibers.
[0034] In the context of the present invention, the reinforcement 10 can be made in two ways. According to a first method, the reinforcement 10 is made by weaving the threads 12. The weaving can be done in three dimensions as shown in [Fig. 1]. The reinforcement then presents itself in the form of a fibrous preform obtained by three-dimensional weaving.
[0035] According to a second method, the wires 12 are used to produce the reinforcement 10 by additive manufacturing. It is understood that the wires can be in the form of at least one spool that feeds an additive manufacturing machine. This additive manufacturing machine includes a head that is fed by the spool and that performs the additive manufacturing of the reinforcement 10 on a printing substrate.
[0036] In the context of the present invention, the presence of pores 14, 15 in the ceramic reinforcement is important because these pores 14, 15 are intended to be filled, at least partially, by the ceramic matrix 11. The matrix 11 is, for example, made of SiC. This is achieved by gaseous infiltration of the reinforcement 10 using a method such as CVI, which is well known to those skilled in the art. In this method, ceramics can be deposited from gaseous precursors within the ceramic reinforcement 10. The filling of a pore 14, 15 by CVI results from two phenomena: (i) a surface reaction and (ii) mass transfer of reactants and products in the gas phase.
[0037] As mentioned above, the pores 14, 15 of the ceramic reinforcement 10 are defined on the one hand by the inter-wire spaces within the reinforcement 10, and on the other hand by the intra-wire spaces or interfilaments within the wires 12. The intra-wire pores (or micropores 15) may prove to be too small to ensure good infiltration of the gas precursors inside the reinforcement 10 and in particular the wires 12.
[0038] The process according to the invention thus comprises two steps:
[0039] a) preparation of the ceramic reinforcement 10, this ceramic reinforcement 10 being porous and being formed by threads 12 which define macropores 14 between them, each of the threads 12 being formed of a plurality of filaments 13 which define micropores 15 between them, the macropores and micropores being called pores 14, 15,
[0040] b) gaseous infiltration of the ceramic reinforcement 10 so as to at least partially fill said pores 14, 15 and to form said ceramic matrix 11.
[0041] Figures 2a and 2b show a wire 12 used in the preparation of a reinforcement 10 of the prior art. It can be seen that the filaments 13 are too tightly packed together to allow good infiltration between them. Consequently, the part obtained with this type of reinforcement will not have a homogeneous ceramic matrix 11, and in particular, a ceramic matrix 11 that will sufficiently fill the micropores 15 between the filaments 13 of the wires 12.
[0042] To solve this problem, the invention proposes to produce the ceramic reinforcement 10 in step a) with wires 12 which comprise, in addition to the filaments 13, ceramic fillers 18 and a polymeric binder 20 which ensures the retention of the fillers 18 and the filaments 13 (see [Fig. 4]). This yields sheathed wires 12 whose sheath is formed by the binder 20 helps to hold the charges 18 which are intercalated between the filaments 13 so as to keep them apart from each other.
[0043] The ceramic filler content in the binder 20 is preferably between 1 and 10% by volume. This is a relatively low filler content so as not to interfere with the preparation of the reinforcement 10 in step a), but nevertheless sufficient to achieve the desired result, namely the separation of the filaments 13 before the infiltration step. Furthermore, this content prevents a significant increase in the viscosity of the binder 20 and does not affect the prepregability of the yarns 12. Finally, this content prevents damage to the yarns 12, particularly during weaving.
[0044] The ceramic fillers 18 are for example chosen from SiC, BN and Si3N4. The ceramic fillers 18 preferably have a diameter D50 (at least 50% of the filler population have this average diameter) between 2 and 1 Oqm.
[0045] Figure 3 shows the principle of making a sheathed wire 12. Initially, the wire 12, which has a continuous elongated shape, is wound around a spool 22. Once the wire 12 is impregnated with the binder 20 containing the fillers 18, it can also be wound around a spool 23.
[0046] The process includes, between steps a) and b), a step i) of removing at least part of the binder 20 from the wires 12, the filaments 13 remaining separated from each other by the fillers 18. It is then understood that the fillers make it possible to create interfilament or intrafilament spaces which will be larger than in the prior art and which will therefore make it possible to create micropores of larger dimensions than in the prior art.
[0047] We will now look at the manufacturing method of the impregnated wires on the one hand, and the removal of the binder from these wires on the other hand.
[0048] With regard to the manufacture of sheathed or impregnated wires, the wires 12 can be coated with the binder 20 by pultrusion, and in particular by pultrusion by impregnation.
[0049] Pultrusion is a manufacturing process for fiber-reinforced polymer composites that allows the continuous production of rods with a constant profile. The low production cost, short cycle time, and the ability to manufacture rods with fiber content of up to 70% by volume make this manufacturing method for continuous fiber rods very attractive.
[0050] Figure 5 shows a common pultrusion apparatus. The apparatus generally consists of a creel 24, an impregnation and shaping system 25, a traction device 26, and then a cutting device 28, for example, a saw. The creel 24 allows for the storage of wire spools and the application of tension to the wires.
[0051] Different types of impregnation and shaping systems are available. For example, for impregnation pultrusion according to [Fig. 6], the wires 12 can The wires 12 first pass through a preheating module 30 to pyrolyze a coating present on them. They are then impregnated in a bath 32 of binder containing ceramic fillers. The binder-coated wires 12 are then drawn through a die that controls their diameter and determines the wire shape (circular, rectangular, etc.). The coated wire is then solidified to prevent loss of the fillers and desolidification of the coated wire.
[0052] If the binder is photosensitive, it would be solidified in step a) by UV treatment to induce polymerization. The solidification of the coated wire would then take place in a UV curing chamber 34 ([Fig. 6]). The main advantage of UV curing is the ability to modulate / adjust the degree of crosslinking (and therefore the wire's rigidity) in real time by varying the intensity and duration of exposure.
[0053] The binder used in the context of the present invention may comprise at least one polymer and preferably comprises a mixture of polymers.
[0054] To be photosensitive, the binder or one of its polymers may comprise photosensitive functional groups, that is, groups capable of reacting under the effect of light to induce their polymerization or crosslinking. Examples of these functional groups include diazo, azide, cinnamic, furanic, acrylate, and epoxide groups.
[0055] With regard to step i) and the removal of the binder from the yarns, this removal can be carried out for example by solubilization or degradation of the binder or one of its polymers.
[0056] The rate of binder removed at this stage can be between 50 and 100% and preferably at least 80% in order to ensure effective retention of the charges until the gas consolidation stage without risk of contamination of the CVI furnace.
[0057] The binder may, for example, be a solvent-soluble binder or may comprise a solvent-soluble polymer. The removal of the binder in step i) is then carried out by solubilizing the polymeric binder or its solvent-soluble polymer with this solvent.
[0058] The polymeric binder or its polymer is preferably organic. The polymeric binder or its polymer can be chosen from polysaccharides, protein-based polymers, gelatins, casein, polyvinylpyrrolidone, polyethylene glycol and polyvinyl alcohol.
[0059] The solvent can be water.
[0060] Alternatively, the binder may, for example, be a thermally degradable binder or may comprise a thermally degradable polymer. The removal of the binder in step i) is then carried out by heat treatment.
[0061] The polymeric binder or its polymer is then preferably chosen from: TPU, TPE, TPC, ABS, PC, PLA, PET, PA6, PEEK, PP, etc.
[0062] The binder removal step can be carried out at the same time as the heat treatment step of the fabrics, in conformer, at the time of the temperature rise of the gas consolidation step for example.
[0063] The invention thus proposes a method for separating the filaments of the wires of a reinforcement by incorporating ceramic fillers between the filaments so that the fillers are fixed and remain in place until the consolidation phase of the reinforcement, thus allowing better gas infiltration into the different pores of the reinforcement and in particular into the micropores between the filaments of the wires of the reinforcement.
[0064] Figures 7a and 7b show that the spacing of the filaments 12 makes it possible to enlarge the micropores 15 of the ceramic reinforcement 10 and thus to facilitate gas infiltration and the homogeneity of the matrix 11 at the end of the process.
[0065] Another advantage of the binder 20 is that it protects the yarns and filaments 12 during the preparation of the reinforcement 10 in step a). The binder 20 improves the resistance of the yarns 12 and filaments 13 to abrasion and friction and prevents their damage (filament fibrillation) or breakage during step a). The binder 20 of the yarns 12 effectively eliminates the need for the wrapping step of the prior art to protect the yarns 12.
Claims
Demands
1. A method for manufacturing a ceramic matrix composite part, particularly for the aerospace industry, the composite part comprising a ceramic reinforcement (10) embedded in a ceramic matrix (11), the method comprising the following steps: a) preparation of the ceramic reinforcement (10), this ceramic reinforcement being porous and formed by wires (12) which define macropores (14) among themselves, each of the wires (12) being formed of a plurality of filaments (13) which define micropores (15) among themselves, the macropores and micropores being called pores (14, 15), b) gas infiltration of the ceramic reinforcement (10) so as to at least partially fill said pores (14) and to form said ceramic matrix (11), characterized in that, during step a), the ceramic reinforcement (10) is prepared with wires (12) which comprise, in addition to the filaments (13),ceramic fillers (18) and a polymeric binder (20) which ensures the retention of the fillers (18) and the filaments (13), the fillers (18) being intercalated between the filaments (13) so as to keep them apart from each other, and in that the process comprises, between steps a) and b), a step i) of removing at least a part of the binder (20) from the filaments (12), the filaments (13) remaining separated from each other by the fillers (18).
2. A method according to claim 1, wherein the ceramic reinforcement (10) is prepared in step a) by additive manufacturing.
3. Method according to claim 1, wherein the ceramic reinforcement (10) is prepared in step a) by weaving, in particular in three dimensions.
4. A method according to claim 3, wherein the filaments (13) are fibers, in particular made of SiC.
5. A method according to any one of the preceding claims, wherein the polymeric binder (20) is a solvent-soluble binder or comprises a solvent-soluble polymer, the removal of the binder in step i) being carried out by solubilizing the polymeric binder or its solvent-soluble polymer with said solvent.
6. A method according to claim 5, wherein the polymeric binder (20) or its polymer is organic.
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15. A method according to claim 6, wherein the polymeric binder (20) or its polymer is selected from polysaccharides, protein-based polymers, gelatins, casein, polyvinylpyrrolidone, polyethylene glycol and polyvinyl alcohol. A process according to any one of claims 5 to 7, wherein the solvent is water. A method according to any one of claims 1 to 4, wherein the polymeric binder (20) is a thermally degradable binder or comprises a thermally degradable polymer, the removal of the sheath in step i) being carried out by heat treatment. A method according to any one of the preceding claims, wherein the ceramic fillers (18) are selected from SiC, BN and Si3N4. A method according to any one of the preceding claims, wherein, during step a), the wires (12) are prepared by pultrusion, and in particular by impregnation pultrusion. A method according to any one of the preceding claims, wherein, during step a), the fillers (18) are mixed with the binder (20) and then the binder with the fillers impregnates the wires (12). A method according to any one of the preceding claims, wherein the binder (20) is photosensitive and is solidified in step a) by UV treatment so as to cause its polymerization. A method according to any one of the preceding claims, wherein the proportion of ceramic fillers (18) in the binder (20) is between 1 and 10% by volume. Method according to any one of the preceding claims, wherein the ceramic fillers (18) have a diameter D50 between 2 and 1 Opm.