A method for producing a component made of a composite material

Abstract

The present invention relates to a method for producing a component made of a composite material, the method comprising at least: - obtaining a mold, the mold comprising: (i) a fibrous texture (6); (ii) a granular filter layer (5a) located between the drainage surface (SD) of the texture and the permeable discharge surface (4), the granular filter layer comprising a powder of filter particles (50a); and (iii) an element (5b) for holding the granular layer, which element is different from the layer and is located between the permeable discharge surface and the drainage surface, - introducing a suspension (1) comprising matrix particles (PM) into a liquid medium (ML) through an introduction surface (SI) of the fibrous texture different from the drainage surface, the liquid medium passing through the drainage surface, the granular filter layer and the holding element and being discharged through the permeable discharge surface, the matrix particles being retained by the granular filter layer in the pores of the fibrous texture, and - forming a component made of a composite material by forming a matrix from the matrix particles in the pores of the fibrous texture and forming a surface layer of the component from the filter particles.

Description

Technical Field

[0001] The present invention relates to a method for producing a component made of a composite material, in which a material intended to form a matrix is provided by introducing a suspension into a reinforcing texture, and the liquid medium of the suspension is discharged from the texture through a granular layer intended to be added to the obtained component. The present invention particularly relates to applications in the production of turbine components (such as aerospace turbine components). Background Art

[0002] It is well known that components made of composite materials are produced by introducing a powder into the pores of a fibrous texture by infiltration of a suspension, for example using the STM ("Slurry Transfer Molding") method. In this case, the liquid medium of the suspension is discharged or filtered while the powder intended to form the matrix of the component is retained in the pores of the texture. This method is specifically described in document WO 2016 / 102839, which proposes the implementation of a rigid component made of a porous polytetrafluoroethylene (PTFE) material that is inserted between the fibrous texture and the molding surface, and the liquid medium of the suspension is discharged via the molding surface. Then, during demolding after infiltration, the component made of the porous material separates from the fibrous texture. However, the rigidity of the component made of the porous material used limits its ability to adapt to complex geometries, and the implementation cost of this technology is relatively high.

[0003] The present invention aims to overcome the drawbacks of the prior art. Summary of the Invention

[0004] The present invention relates to a method for producing a component made of a composite material, the method comprising at least:

[0005] - obtaining a mold, the mold comprising: (i) a fibrous texture; (ii) a granular filter layer located between the drainage surface of the texture and a permeable discharge surface, the granular filter layer comprising a powder of filter particles; and (iii) an element for holding the particle layer, which is different from the layer and is located between the permeable discharge surface and the drainage surface,

[0006] - introducing a suspension containing matrix particles into the liquid medium through an introduction surface of the fibrous texture different from the drainage surface, the liquid medium passing through the drainage surface, the granular filter layer, and the holding element and being discharged through the permeable discharge surface, and the matrix particles being retained in the pores of the fibrous texture by the granular filter layer, and

[0007] - forming a component made of a composite material by forming a matrix from the matrix particles in the pores of the fibrous texture and forming a surface layer of the component from the filter particles.

[0008] The present invention proposes the use of a granular filter layer, which is intended to be integrated into the obtained composite material part, which allows avoiding the step of removing the porous part encountered in the prior art and the limitations in terms of accessible geometry related to the rigidity of the porous part. The retaining element prevents the filtration particles from being carried outside the mold during the discharge of the liquid medium.

[0009] In an exemplary embodiment, the granular filter layer further comprises reinforcing fibers different from the filtration particles.

[0010] This feature advantageously allows improving the mechanical properties of the surface layer of the obtained part.

[0011] In an exemplary embodiment, the retaining element comprises at least one membrane or textile having a plurality of holes for discharging the liquid medium and located between the granular filter layer and the permeable discharge surface.

[0012] In an exemplary embodiment, the retaining element comprises at least one particle assembly formed by additional filtration particles having an average size different from that of the filtration particles and / or a shape different from that of the filtration particles, and interlocking with the filtration particles to prevent them from moving towards the permeable discharge surface.

[0013] Unless otherwise specified, "average size" refers to the size given by the statistical particle size distribution of half of the population, called D 50 。

[0014] Specifically, the average size of the additional filtration particles is less than or equal to three times the average size of the filtration particles, for example, less than or equal to the average size of the filtration particles.

[0015] The granular filter layer can be placed in the mold in different ways.

[0016] According to the first example, the obtained mold comprises: the granular filter layer is placed in the form of a block, which block comprises filtration particles bound together by a short-acting binder.

[0017] According to another example, the obtained mold comprises: spraying the filtration particles onto the fibrous drainage surface and / or the permeable discharge surface.

[0018] According to an example, the obtained mold comprises: (a) forming a granular filter layer containing filtration particles; and (b) supplying additional filtration particles in a carrier liquid, which carrier liquid is discharged through the filtration particles and the drainage surface, and the additional filtration particles are retained by the filtration particles to form a retaining element.

[0019] Specifically, the granular filter layer can be formed by adding filter particles to a second carrier liquid on one side of the drainage surface. The particle size of the filter particles can be larger than the gap size of the pore network of the fibrous texture, and the second carrier liquid drains through the drainage surface. The filter particles can be retained by the fibrous texture, thereby forming the granular filter layer.

[0020] In an exemplary embodiment, the matrix is formed by sintering matrix particles, and the surface layer is formed by sintering filter particles.

[0021] Using sintering advantageously allows the matrix and the surface layer to be formed at a limited implementation cost.

[0022] In an exemplary embodiment, the matrix particles and the filter particles are formed of the same material.

[0023] This feature advantageously allows for optimal compatibility between the component matrix and the surface layer.

[0024] In an exemplary embodiment, the matrix particles and the filter particles are made of an oxide ceramic material, silicon carbide, or carbon.

[0025] In an exemplary embodiment, the component is a turbine component, for example, an aerospace turbine component. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Figure 1 is a schematic cross-sectional view showing an example part of the method according to the invention, in which matrix particles are introduced into the texture pores.

[0027] Figure 2 Figure 2 Schematically shows a component obtained by heat-treating a texture obtained according to Figure 1 the example.

[0028] Figure 3 Figure 3 is a schematic cross-sectional view showing the case of introducing matrix particles into the texture pores in accordance with a variant method of the invention.

[0029] Figure 4 Figure 4 Schematically shows in part a granular filter layer that can be used in the present invention.

[0030] Figure 5 Figure 5 Schematically shows in part another granular filter layer that can be used in the present invention.

[0031] Figure 6A Figure 6A Schematically shows in part an example of a granular filter layer that can be used in the present invention. ​​​​​​​​​​​​

[0032] Figure 6B Figure 6B The schematic part shows an example of a holding element in the form of a granular component related to the granular layer and usable in the present invention. Figure 6A The granular layer-related holding element in the form of a granular component usable in the present invention is shown in the schematic part. Detailed Description

[0033] Figure 1 A mold formed by connecting an upper tool 8 and a lower tool 2 is shown. The mold includes a molding surface 4 (e.g., a molding surface formed of a rigid material) which is intended to impart its shape to the surface of a part to be obtained located opposite thereto. In Figure 1 the example, the molding surface 4 forms a permeable surface allowing a liquid medium ML to be discharged from the suspension 1 to the outside of the mold. A fibrous texture 6 is present in the mold and has a granular filter layer 5a containing a large number of filter particles 50a along one of its surfaces SD (referred to as the drainage surface). The particles 50a may be in contact with the surface SD. A holding element in the form of a porous layer 5b for retaining the particles 50a is located between the layer 5a and the molding surface 4 and has pores fine enough to retain the particles 50a in a position against the texture 6 during the discharge of the liquid medium ML during the introduction of the suspension 1. As shown, the layers 5a and 5b may substantially cover the entire surface SD. The particles 50a may be in contact with the layer 5b. The layer 5b may be in contact with the molding surface 4.

[0034] The particles 50a are formed of a material compatible with the integration of the composite part. For example, if the part is an oxide / oxide composite, the particles 50a may be made of alumina (Al2O3), if the part is a part with a silicon carbide matrix, the particles 50a may be made of silicon carbide (SiC), and if a carbon matrix part is produced, the particles 50a may be made of carbon or graphite. To ensure optimal compatibility, the particles 50a formed of the same material as the matrix particles PM may be used, but those skilled in the art will recognize that variations can be made without departing from the scope of the present invention. Generally, the average size of the particles 50a may be greater than the average size of the matrix particles PM. The average size of the particles 50a may be 1 to 50 times, particularly 1 to 30 times or 1 to 3 times, the average size of the matrix particles PM. Generally, the thickness of the layer 5a e may be between 5 and 1000 times, particularly between 10 and 500 times, the average size of the matrix particles PM. For example, the thickness of the layer 5a e may be 4 μm to 200 μm.

[0035] ​​The texture 6 is intended to form the reinforcement of the composite part. The production of the texture 6 uses techniques known per se, such as the stacking of two-dimensional fabrics, three-dimensional weaving or the placement of unidirectional fiber strips. The wires used to form the texture 6 can be made of ceramic materials, such as carbides or oxides, or of carbon. Specifically, if an oxide / oxide composite part is produced, alumina wires can be used.

[0036] The layer 5b allows the particles 50a to remain against the drainage surface SD of the texture 6. In the example as Figure 1 shown, the layer 5b is formed by a membrane including a plurality of through-holes or by the superposition of a plurality of such membranes. The size of the holes is selected according to the size of the particles 50a to ensure their retention. For example, the average size of the holes can be from 10 μm to 100 μm, and the surface opening ratio of the membrane (corresponding to the total surface area of the holes / the ratio of the membrane surface) can be from 0.1% to 2%. The layer 5b can be made of a polymeric material. Alternatively, a layer 5b formed by a textile (such as a fabric) can be used. Generally, the thickness of the layer 5b is usually less than or equal to 100 μm. In Figure 1 the case, since the particles 50a are inserted between the texture 6 and the layer 5b, they are not bonded together and remain in place. The layer 5a can be in the form of a granular bed, here including a plurality of agglomerated grains formed by the particles 50a. The particles 50a can have a substantially spherical or oval shape. However, other structures can also be used for the granular filter layer. According to Figure 4 a variant, the filter layer 15a also includes reinforcing fibers 52a present in the gaps between the particles 50a, here in the form of discontinuous fibers. The volume fraction of the fibers 52a in the layer 15a can be substantially equal to the volume ratio of the fibers required in the texture 6 densified by the matrix. The discontinuous fibers 52a can be short fibers with an average size less than or equal to 30000 μm, or can be in the form of individual filaments. According to a variant, the reinforcing fibers can be bonded together to form a textile, such as a fabric or a non-woven fabric. The fibers added to the filter layer are of course formed of a material compatible with the integration of the composite part. In a particular case, the fibers 52a can be formed of the same material as the particles 50a and possibly of the same material as the matrix particles PM. According to Figure 5 a variant, the filter layer 25a is in the form of a mass including particles 50a bonded together by a short-term binder 54a, which is intended to be eliminated during the process. Eliminating the binder 54a allows the pores between the particles 50a to be released, thus discharging the liquid medium ML in the suspension. For example, a binder 54a soluble in the liquid medium ML can be selected, or a binder 54a capable of being removed thermally can be selected. Of course, in Figure 4In the case of , the fibers 52a can be added to the binder 54a and the particles 50a. When placing the element in the mold, the layer 5a can be deposited, and then the texture 6 can be placed and the mold closed. This deposition can be done by manual placement or by spraying the particles 50a onto the layer 5b and / or the surface SD.

[0037] Figure 6A and 6B The case of involves a variant where the retaining element includes additional filter particles 25b different from the particles 50a forming the layer 5a. In this case, the adjusted pore layer 5b can be added or not added to allow retention of the above-mentioned particles. Figure 6A Shows a granular filter layer formed by the particles 50a, which can be produced by the above deposition. Alternatively, the texture 6 can first be placed in the mold, and then the particles 50a can be infiltrated by a carrier liquid supplied from the surface SD side. In Figure 1 the example of , this infiltration can be carried out through the lower part of the mold through the molding surface 4. The particle size of the particles 50a is selected to be larger than the size of the pore network gaps of the texture 6, so that they do not pass through it and remain facing the surface SD. The particles 50a have been shown as being substantially spherical, but when these particles 50a have different shapes, for example when they are substantially polyhedral in shape so as to interlock with each other, and once packed or compacted and "soaked", their movement becomes difficult, this does not depart from the scope of the present invention. Then, the supply of the particles 25b can also be continued by infiltration with a carrier liquid the same as or different from the carrier liquid used for supplying the particles 50a. The movement of the particles 25b towards the texture 6 is hindered by the particles 50a, and some of the particles 25b are accommodated in the gaps existing between the particles 50a. In the example shown, the particles 25b have a finer particle size than the particles 50a, preferably 2 to 20 times smaller, so as to interlock into the gaps between the particles 50a. Preferably, at least a part of the particles 25b have a polyhedral shape so as to interlock with each other and stick between the particles 50a. In the example shown, the particles 25b have a different shape from the particles 50a, but when this is not the case, it does not depart from the scope of the present invention. Thus, a set of interlocked particles 50a and 25b is obtained, resulting in an overall blockage. This interlock prevents the particles 50a from moving towards the molding surface 4 during the discharge of the liquid medium ML. According to one example, for a texture 6 with a filament diameter of 10 μm to 20 μm, an inter-filament space of 1 μm to 5 μm, and an inter-fiber space up to 50 μm, particles 50a with a particle size of 5 μm to 50 μm and particles 25b with a particle size of 0.2 μm to 5 μm can be used. The case of adding the particles 25b by infiltration has been described, but if the particles 50a and 25b are co-deposited by spraying or have been combined by a short-acting binder in a manner similar to the above, it does not depart from the scope of the present invention. In Figure 6BIn the example, all particles 50a and 25b are inserted between the texture 6 and the molding surface 4. The cases of two groups of particles 50a and 25b with different particle sizes have been shown, but if particles with a larger particle size are used, the average particle size of the filtering particles generally decreases when moving from the texture 6 towards the molding surface 4, and it will not deviate from the scope of the present invention. For example, a first group of filtering particles located in a first region on one side of the surface SD can be used, with a first average size being 0.5 times to 3.5 times the filament diameter of the texture 6, preferably 0.5 times to 1.5 times that diameter; a second group of filtering particles is at least partially located in a second region between the first region and the molding surface 4, with a second average size being 0.1 times to 1 times the filament diameter of the texture 6; and a third group of filtering particles is at least partially located in a third region between the second region and the molding surface 4, with a third average size being 0.03 times to 0.8 times the filament diameter of the texture 6. In this example, the first, second, and third groups of filtering particles are interlocked with each other, the third average size is smaller than the second average size, and the second average diameter is smaller than the first average size.

[0038] Once all the elements are placed in the mold, the matrix particles PM are introduced into the pores of the texture 6, as Figure 1 shown. These particles PM are introduced into the texture 6 by techniques known per se. A suspension 1 containing the matrix particles PM in a liquid medium ML is initially stored in a container C1 located outside the mold. The liquid medium ML can be aqueous or alcoholic. The average size of the matrix particles PM can be from 0.1 μm to 2 μm. The particles PM can be made of ceramic, carbon, or a carbon precursor. Before being introduced into the texture 6, the volume content of the particles PM in the suspension 1 can be from 5% to 50%. The container C1 is connected to the mold through a conduit 80, which opens at a port 8a upstream of the texture 6. Here, unless otherwise specified, "upstream" and "downstream" refer to the flow direction of the liquid medium ML of the suspension 1. A pump 82 is present on the conduit 80 and allows the suspension 1 to flow from the container C1 towards the port 8a in order to introduce it into the mold. As an alternative to the pump 82, a device for pressurizing the suspension 1 in C1 relative to the tool to cause the suspension 1 to flow can be used. The flow of the suspension 1 upstream of the texture 6 is as Figure 1As shown by arrow E1 therein. For example, a distributor 7 in the shape of a grid allows the suspension 1 to be evenly distributed on the surface SI, introducing the texture 6 opposite to the surface SD. The use of this distributor 7 is optional. The suspension 1 flows into the texture 6 through the surface SI, and the layer 5a retains the matrix particles PM in the pores of the texture 6. The liquid medium ML is discharged outside the mold through the surface SD, the layers 5a and 5b, and the permeable molding surface 4. Along the flow path of the liquid medium ML, the texture 6 exists between the port 8a and the port 2a. Along the flow path of the liquid medium ML, the layer 5a exists between the texture 6 and the port 2a. Along the flow path of the liquid medium ML, the layer 5b exists between the layer 5a and the port 2a. Then, the liquid medium ML flows through the cavity 3 defined by the molding surface 4, flows towards the port 2a located downstream of the texture, and is connected to the container C2 through the conduit 20. The container C2 is different from the container C1 and is located outside the mold (flow arrow EML). The liquid medium ML is collected in the container C2. Thus, the texture 6 loaded with the matrix particles PM is obtained. During the introduction of the matrix particles PM, the texture 6 can be held in the mold in a compressed state. This compression can facilitate the discharge of the liquid medium ML and allow the target thickness of the fiber preform to be achieved.

[0039] The method is continued by forming a matrix through heat treatment of the texture 6 loaded with the particles PM and the filtering particles 50a. According to Figure 2 the example in, the matrix particles PM and the particles 50a are sintered to obtain a component 100 made of a composite material. The component 100 includes a base material 102 and a surface layer 104. The reinforcement of the base material 102 is formed by the texture 6 and densified by the matrix obtained from the matrix particles PM. The surface layer 104 is formed by the particles 50a, where it is obtained by sintering these particles 50a. Then, the component 100 including the base material 102 and this surface layer 104 is demolded and then assembled, for example, in an aero turbine. As an example of the component 100, an aeroengine injection component can be mentioned, such as a nozzle ("exhaust nozzle") or an ejection plug, or an aft aerodynamic fairing (for "Aft Pylon Fairing" (APF)). It should be recognized that other methods can also be used to produce the matrix and the surface layer. According to a variant, particles 50a and matrix particles PM made of carbon or silicon carbide can be used and infiltrated with molten silicon to obtain a ceramic matrix and a SiC or Si - SiC surface layer.

[0040] Just combined Figure 1 described the introduction of the suspension 1 through the upper part of the texture 6. Figure 3 The example of is a variant, showing the possibility of introducing the suspension 1 through the lower part of the texture 6 and draining and discharging the liquid medium through its upper part. This figure includes the same asFigure 1 Reference numerals for elements having the same function in Figure 3 In the case of [[ID=]], the texture 6 can first be placed on the molding surface 4, then the granular filter layer 5a, then the holding layer 5b, and then the mold is closed. Here, the discharge of the liquid medium ML is effected through the permeable surface 41 which communicates with the port 8a in the upper part of the mold.

[0041] The term “... to...” shall be understood to include the end values.

Claims

1. A method for producing a component (100) made of a composite material, the method comprising at least: - obtaining a mold, the mold comprising: (i) a fibrous texture (6); (ii) a granular filter layer located between the drainage surface (SD) of the texture and a permeable discharge surface, the granular filter layer comprising a powder of filter particles (50a); and (iii) a retaining element (5b) for retaining the granular filter layer, the retaining element being different from the granular filter layer and located between the permeable discharge surface and the drainage surface, - introducing a suspension (1) containing matrix particles (PM) into a liquid medium (ML) through an introduction surface (SI) of the fibrous texture different from the drainage surface, the liquid medium passing through the drainage surface, the granular filter layer and the retaining element and being discharged through the permeable discharge surface, the matrix particles being retained by the granular filter layer in the pores of the fibrous texture, and - forming a component made of a composite material by forming a matrix from the matrix particles in the pores of the fibrous texture and forming a surface layer (104) of the component from the filter particles.

2. The method according to claim 1, wherein The granular filter layer further comprises reinforcing fibers (52a) different from the filter particles (50a).

3. The method according to claim 1, wherein The retaining element (5b) comprises at least one membrane or textile having a plurality of holes for discharging the liquid medium (ML) and located between the granular filter layer and the permeable discharge surface.

4. The method according to claim 1, wherein, The retaining element comprises at least one particle assembly formed by additional filter particles (25b), the additional filter particles having an average size different from that of the filter particles (50a) and / or a shape different from that of the filter particles (50a) and being interlocked with the filter particles (50a) to prevent them from moving towards the permeable discharge surface.

5. The method according to any one of claims 1 to 4, wherein Obtaining the mold comprises: placing the granular filter layer in the form of a mass, the mass comprising filter particles (50a) bound together by a short-term binder (54a).

6. The method according to any one of claims 1 to 4, wherein Obtaining the mold comprises: spraying the filter particles (50a) onto the drainage surface (SD) of the fibrous texture and / or onto the permeable discharge surface.

7. The method according to claim 4, wherein Obtaining the mold comprises: (a) forming a granular filter layer containing filter particles (50a); and (b) supplying additional filter particles (25b) in a carrier liquid, the carrier liquid being discharged through the filter particles and the drainage surface, the additional filter particles being retained by the filter particles (50a) to form the retaining element.

8. The method according to claim 5, wherein Obtaining the mold comprises: (a) forming a granular filter layer containing filter particles (50a); and (b) supplying additional filter particles (25b) in a carrier liquid, the carrier liquid being discharged through the filter particles and the drainage surface, the additional filter particles being retained by the filter particles (50a) to form the retaining element.

9. The method according to claim 6, wherein, Obtaining the mold comprises: (a) forming a granular filter layer containing filter particles (50a); and (b) supplying additional filter particles (25b) in a carrier liquid, the carrier liquid being discharged through the filter particles and the drainage surface, the additional filter particles being retained by the filter particles (50a) to form the retaining element.

10. The method according to claim 7, wherein, The granular filter layer is formed by adding filter particles (50a) to a second carrier liquid on the side of the drainage surface (SD), the particle size of the filter particles being larger than the gap size of the pore network of the fibrous texture (6), and the second carrier liquid draining through the drainage surface, with the filter particles retained by the fibrous texture, thereby forming the granular filter layer.

11. The method according to claim 1, wherein, The matrix is formed by sintering matrix particles (PM), and the surface layer (104) is formed by sintering filter particles (50a).

12. The method according to claim 1, wherein, The matrix particles (PM) and the filter particles (50a) are formed of the same material.

13. The method according to claim 1, wherein, The matrix particles (PM) and the filter particles (50a) are made of an oxide ceramic material, silicon carbide, or carbon.

14. The method according to claim 1, wherein The component is a turbine component.

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