Tooling and process for infiltrating a slip into a textile preform

Abstract

Tool and method for infiltrating a slip into a textile preform Tool for infiltrating (100) a slip (120) into a textile preform (110) comprising: - a mold (102) which comprises an impregnation chamber (103) comprising on one of its faces a filtration element (130) for a liquid phase (131) of the slip intended to receive a first face (113) of a textile preform (110), the impregnation chamber being closed by a counter-mold (101) located opposite the filtration element;and - an outlet vent (132) present on the mold and configured to remove a filtrate (131) from the filtration element at a removal pressure (P2), characterized in that the tooling also comprises a system for circulating a slip comprising an inlet port (141) and an outlet port (142), the circulation system being configured to circulate the slip in the impregnation chamber from the inlet port to the outlet port at a circulation pressure (P1) higher than the removal pressure (P2). Figure for abstract: Fig. 1;

Description

Title of the invention: Tooling and method for infiltrating a slip into a textile preform Technical field

[0001] The present invention relates to the general field of manufacturing parts made of composite material, and more particularly to a tool and a method for infiltrating a slip into a textile preform to form a matrix in the porosity of this preform. Prior art

[0002] Densification, i.e. the formation of a matrix, of a textile preform can be carried out by slip injection. It consists of impregnating the textile preform with a liquid-based impregnation composition or slip which penetrates into the porosity of the preform and causes a matrix to grow in this preform.

[0003] Document FR 3 080 113 describes an example of slip infiltration into a textile preform, in which the preform is arranged in an impregnation chamber of a mold closed by a flexible membrane. A filter is present under the preform so as to filter a liquid phase (filtrate) of the slip which is injected into the impregnation chamber. A pressure, greater than the slip injection pressure, is applied to the flexible membrane so as to cause the slip to penetrate into the preform. This example of infiltration is called Under-Membrane Injection or ISM.

[0004] It is also possible to carry out this slip impregnation by STM (Slurry Transfer Molding) or slip injection molding, as described in document FR 3 030 505. In this case, it is the rigid walls of the mold which compact the preform during and / or after the injection of slip into the impregnation chamber to cause the slip to penetrate into the preform.

[0005] However, during impregnation by STM or ISM, the growth of the matrix deposition thickness in the preform is not controlled, but only the balance of the pressure losses (present in the slip) between the slip inlet orifice and the filtrate. It is therefore possible to obtain a deposition front of the solid charges of the slip blocking the slip inlet orifice in the impregnation chamber while the preform is not completely colonized with solid charges. It is possible to reduce this phenomenon by placing a draining material above the preform, acting as a distribution element between the inlet orifice and one of the faces of the preform. But in return, this increases the quantity of slip to be injected into the impregnation chamber and the filtration time of the liquid phase of slip.

[0006] It is therefore desirable to have new tooling and a new method for infiltrating slip into a textile preform making it possible to overcome the aforementioned drawbacks, in particular so that the solid particles of the slip colonize the entire preform without increasing the quantity of slip injected. Statement of the invention

[0007] The invention relates to a tool for infiltrating a slip into a textile preform comprising:

[0008] - a mold which comprises an impregnation chamber comprising on one of its faces a filtering element for a liquid phase of the slip intended to receive a first face of a textile preform, the impregnation chamber being closed by a counter-mold located opposite the filtering element, and - an outlet vent present on the mold and configured to eliminate a filtrate from the filtering element at an elimination pressure,

[0009] characterized in that the tooling also comprises a slip circulation system comprising an inlet port and an outlet port, the circulation system being configured to circulate the slip in the impregnation chamber from the inlet port to the outlet port at a circulation pressure greater than the removal pressure.

[0010] Thanks to the circulation system, the slip circulates under pressure in the impregnation chamber and does not stagnate. This prevents the particles or powder contained in the slip from settling and agglomerating between the preform and the counter-mold, thus preventing the growth of granular matrix between the textile preform and the counter-mold. Thus, the agglomeration of the particles or powder of the slip only occurs for the slip impregnating the textile preform. In addition, the elimination pressure allows the liquid phase of the slip to be evacuated through the filtration element and the outlet vent.

[0011] According to a particular characteristic of the invention, the infiltration tool comprises a recirculation circuit connecting the outlet port to the inlet port so that the slip circulation system is a closed circuit.

[0012] The recirculation circuit may comprise a pump configured to bring the slip to the circulation pressure.

[0013] This allows the slip discharged through the outlet port to be reintroduced into the impregnation chamber. Thus, the amount of slip used for matrix growth in the textile preform can be reduced and optimized.

[0014] According to another particular characteristic of the invention, the circulation system comprises drainage means extending between the inlet port and the outlet port.

[0015] The drainage means are advantageously located at the level of a second face of the textile preform, opposite the first face. The textile preform is thus positioned between the filtration element and the drainage means.

[0016] According to a first embodiment, the drainage means comprise a piece of porous material intended to be placed on a second face of the textile preform opposite the first face. The piece of porous material is for example a grid.

[0017] According to a second embodiment, the drainage means comprise channels placed or formed on an internal surface of the counter-mold and intended to be opposite the second face of the textile preform.

[0018] The first and second embodiments may be combined, i.e. the drainage means may comprise both a part made of porous material and channels placed or formed on an internal surface of the counter-mold.

[0019] According to another particular characteristic of the invention, the inlet and outlet ports are intended to be located opposite a lateral face of the textile preform. When the circulation system comprises drainage means, the inlet and outlet ports are advantageously located opposite a lateral face of these drainage means.

[0020] The inlet and outlet ports are thus located at the periphery of the preform while the filtration element and the outlet vent are located under the preform. The removal pressure at the outlet vent thus does not disturb the circulation of slip, and the slip can circulate well throughout the impregnation chamber to impregnate the entire preform.

[0021] According to another particular characteristic of the invention, the inlet port is present on the counter-mold or on the mold and the outlet port is present on the counter-mold or on the mold.

[0022] According to another particular characteristic of the invention, the tooling also comprises a flexible membrane intended to be located between the counter-mold and the textile preform.

[0023] This makes it possible to carry out the formation of the matrix in the textile preform by ISM.

[0024] Another object of the invention is a method of infiltrating a slip into a textile preform implemented in an infiltration tool according to the invention, the method comprising:

[0025] - placing a textile preform in the impregnation chamber by resting one of the faces of the preform on the filtration element and closing the infiltration tool by placing the counter-mold on the textile preform, and - infiltration by a slip of the textile preform by circulating the slip in the impregnation chamber from the inlet port to the outlet port outlet under a circulating pressure while filtering and removing a liquid phase from the slip through the filter element and the outlet vent under a removal pressure lower than the circulating pressure.

[0026] According to a particular characteristic of the invention, the pressure difference between the circulation and elimination pressure is between 1.105 Pa (1 bar) and 20.105 Pa (20 bars).

[0027] This ensures that the slip circulates well in the impregnation chamber without the particles or powder agglomerating between the counter-mold and the textile preform.

[0028] According to another particular characteristic of the invention, the slip leaving the outlet port is reintroduced into the impregnation chamber via the inlet port.

[0029] According to another particular characteristic of the invention, the circulation speed of the slip in the circulation system is at least twice the filtration speed of the liquid phase of the slip by the filtration element and the outlet vent. Brief description of the drawings

[0030] Other characteristics and advantages of the present invention will emerge from the description given below, with reference to the appended drawings which illustrate exemplary embodiments thereof which are not limiting in nature.

[0031] [Fig-1] [Fig.l] represents, in a schematic and partial manner, a tool infiltration according to one embodiment of the invention.

[0032] [Fig.2] [Fig.2] schematically and partially represents an infiltration tool according to another embodiment of the invention.

[0033] [Fig.3] [Fig.3] schematically represents a method of infiltrating a slip into a textile preform according to one embodiment of the invention.

[0034] [Fig.4A] [Fig.4A] schematically and partially represents an infiltration tool according to an embodiment in the case of a textile preform of variable thickness.

[0035] [Fig.4B] [Fig.4B] schematically and partially represents the infiltration tool of [Fig.4A] and the infiltration of slip into the preform over time.

[0036] [Fig.4C] [Fig.4C] schematically and partially represents the infiltration tool of [Fig.4A] and the infiltration of slip into the preform over time.

[0037] [Fig.4D] [Fig.4D] schematically and partially represents the infiltration tool of [Fig.4A] and the infiltration of slip into the preform over time.

[0038] [Fig.4E] [Fig.4E] schematically and partially represents the infiltration tool of [Fig.4A] and the infiltration of slip into the preform over time. Description of the embodiments

[0039] [Fig.l] schematically and partially represents an infiltration tool 100 according to an embodiment of the invention.

[0040] The tool 100 comprises a mold 102 and a counter-mold 101 which delimit an impregnation chamber 103 in which a textile preform 110 is placed which is impregnated by a slip 120. The counter-mold 101 can be formed by a rigid part or by a flexible membrane. The impregnation chamber 103 comprises in its lower part a filtration element 130 which filters a liquid phase 131 of the slip 120. The slip 120 is intended to allow the formation of a matrix of the part to be manufactured. The slip 120 thus comprises solid particles suspended in a liquid phase.

[0041] At least one outlet vent 132 is present on the mold 102 and makes it possible to eliminate the filtrate 131 from the filtration element 130. The filtration element 130 and the outlet vent 132 make it possible to filter the liquid phase 131 of slip 120 after its impregnation in the textile preform 110. The outlet vent 132 is at an elimination pressure P2.

[0042] More precisely, the filtration element 130 and the outlet vent 132 are located opposite a first main face 113 of the textile preform 110.

[0043] The tool 100 also comprises a slip circulation system 120 comprising a slip reservoir 1200, an inlet port 141, an outlet port 142 and a part made of porous material 160, for example a mesh. The part made of porous material 160 is placed on a second main face 114 of the preform 110, opposite the first main face 113 of the preform 110, opposite the filtration element 130. The preform 110 is thus arranged between the filtration element 130 and the part made of porous material 160. The circulation system makes it possible to circulate the slip 120 in the impregnation chamber 103 from the inlet port 141, supplied by the reservoir 1200, to the outlet port 142 at a circulation pressure PL. The pressure PI is greater than P2. It is considered that the pressure difference between the inlet port 141 and the outlet port 142 is almost zero; in fact, it will be at most of the order of 0.5 bar (0.5.105 Pa).

[0044] The inlet 141 and outlet 142 ports are placed on the counter-mold 101 opposite a lateral face 161, 162 of the part made of porous material 160, in particular the inlet port 141 is opposite the lateral face 161 and the outlet port 142 is opposite the lateral face 162. The two ports 141, 142 are opposite each other in order to allow the slip 120 to circulate in the impregnation chamber 103. Thus, when the slip 120 enters the impregnation chamber 103, a portion of the slip impregnates the textile preform 110 and the other portion exits the chamber 103 through the outlet port 142. By impregnating the preform 110, it deposits fillers (or particles or powder) in the preform 110, which makes it possible to grow a matrix 111 in the porosity of the preform 110; while the liquid phase of the slip 131 is eliminated via the outlet vent 132.

[0045] [Fig.2] schematically and partially represents an infiltration tool 200 according to another embodiment of the invention.

[0046] The tool 200 comprises a mold 202 and a counter-mold 201 which delimit an impregnation chamber 203 in which a textile preform 210 is placed which is impregnated with a slip 220. The impregnation chamber 203 comprises in its lower part a filtration element 230 which filters a liquid phase 231 of the slip 220. As previously, the slip 220 is intended to allow the formation of a matrix and thus comprises solid particles suspended in a liquid phase.

[0047] At least one outlet vent 232 is present on the mold 202 and makes it possible to eliminate the filtrate 231 from the filtration element 230. The filtration element 230 and the outlet vent 232 make it possible to filter the liquid phase 231 of slip 220 after its impregnation in the textile preform 210 at the elimination pressure P2.

[0048] The tool 200 also comprises a slip circulation system 220 comprising a slip reservoir 2200, an inlet port 241, an outlet port 242, a part made of porous material 260 and a recirculation circuit 240 equipped with a recirculation pump 243. The circulation system makes it possible to circulate the slip 220 in the impregnation chamber 203 from the inlet port 241 to the outlet port 242 at a circulation pressure PL. The pressure PI is greater than P2. The recirculation circuit 240 extends between the outlet port 242 and the inlet port 241 so as to be able to return the slip 220 discharged through the outlet port 242 to the inlet port 241. The slip circulation system 220 thus forms a closed loop circuit. As for [Fig.l], it is considered that the pressure difference between the inlet port 241 and the outlet port 242 is almost zero, since it is at most of the order of 0.5 bar (0.5.105 Pa).

[0049] In this embodiment, the same inlet port 241 is used to inject the slip 220 into the impregnation chamber 203, whether it comes from the reservoir 2200 or from the outlet port 242.

[0050] In another embodiment, shown in broken lines in [Fig.2], the circulation system comprises an additional inlet port 244 which allows the slip 220 from the outlet port 242 to be injected into the impregnation chamber 203. The inlet port 241 remains used to inject the slip 220 from the tank 2200.

[0051] As previously, the inlet ports 241 and outlet ports 242 are placed on the counter-mold 201 opposite a lateral face 261, 262 of the part made of porous material 2460, in particular the inlet port 241 is opposite the lateral face 261 and the outlet port 242 opposite the lateral face 262. The additional inlet port 244 is placed in the vicinity of the inlet port 241. The inlet ports 241, 244 are placed opposite the outlet port 242 in order to allow the slip 220 to circulate in the impregnation chamber 203, while the outlet vent 232 is located opposite a main face 213 of the preform 210 in order to be able to evacuate the liquid phase 231 of the slip 220 after its infiltration into the preform 210.

[0052] In order to ensure the circulation of the slip in the impregnation chamber, whether in an open circuit ([Fig.l]) or in a closed loop circuit ([Fig.2]), the slip inlet and outlet ports are placed laterally to the outlet vent, that is to say they are placed opposite a lateral face of the preform and, in the examples of Figures 1 and 2, opposite a lateral face of the porous material, while the outlet vent is opposite a main face of the preform. In addition, the slip inlet ports and outlet port are not located opposite the same lateral face of the preform or the same lateral face of the porous material.

[0053] Whatever the embodiment, the infiltration tool 100 or 200 may comprise a flexible membrane located between the counter-mold 101, 201 and the textile preform 110, 210. This flexible membrane makes it possible, for example, to carry out the infiltration of slip into the preform by ISM.

[0054] Regardless of the embodiment, the circulation system may comprise a plurality of inlet ports and a plurality of outlet ports. The inlet and outlet ports are advantageously distributed around the periphery of the preform in order to promote the circulation of the slip throughout the preform.

[0055] Whatever the embodiment, each inlet port 141, 241, 244 may be present on the mold 102, 202 or on the counter-mold 101, 201 and each outlet port 142, 242 may be present on the mold 102, 202 or on the counter-mold 101, 201.

[0056] The invention has been described with a slip circulation system comprising a part made of porous material. However, the slip circulation system may comprise, instead of or in addition to said part made of porous material, channels placed on an internal surface of the counter-mold which will be opposite the second main face 114, 214 of the preform. The channels extend between the inlet and outlet port.

[0057] In a similar manner to the part made of porous material, the channels make it possible to improve the circulation of the slip in the impregnation chamber and to limit the agglomeration of slip particles between the counter-mold and the preform.

[0058] [Fig. 3] schematically represents a method 300 for infiltrating a slip into a textile preform according to an embodiment of the invention. The method 300 is for example implemented on an infiltration tool 100 or 200 as described with reference to FIGS. 1 and 2.

[0059] The method 300 comprises, in a step 310, the placement of the textile preform 110, 210 in the impregnation chamber 103, 203 by resting one of the faces of the preform on the filtration element 130, 230, the placement of the part made of porous material on the textile preform and the closing of the infiltration tool 100, 200 by placing the counter-mold 101, 201 on the part made of porous material.

[0060] Then, in a step 320, the slip 120, 220 is injected into the impregnation chamber 103, 203 so that it infiltrates the textile preform 110, 210 and circulates in the impregnation chamber 103, 203 from the inlet ports 141, 241, 244 to the outlet port 142, 242. The circulation of the slip 120, 220 is carried out at a circulation pressure PL During the infiltration of the preform 110, 210, the liquid phase 131, 231 of the slip 120, 220 is filtered by the filtration element 130, 230 and evacuated through the outlet vent 132, 232 at an elimination pressure P2 lower than the pressure HGV traffic

[0061] Whatever the embodiment, the pressure difference between P1 and P2 can be between 1.105 Pa (1 bar) and 20.105 Pa (20 bars), it is for example 5.105 Pa (5 bars).

[0062] Whatever the embodiment, the circulation pressure PI can be between 5.105 Pa (5 bars) and 20.105 Pa (20 bars).

[0063] Whatever the embodiment, the elimination pressure P2 is less than or equal to 1.105 Pa (1 bar).

[0064] Regardless of the embodiment, the circulation speed of the slip in the circulation system is at least twice the filtration speed of the liquid phase of the slip by the filtration element and the outlet vent.

[0065] Whatever the embodiment, the slip comprises solid fillers with a rate preferably between 2% and 30% of the volume.

[0066] Whatever the embodiment, for a ceramic part, the slip comprises ceramic fillers with a rate of between 10% and 30% by volume, and preferably an organic binder with a rate of between 0% and 20% by mass and a plasticizer with a rate of between 0% and 20% by mass.

[0067] The ceramic fillers comprise, for example, carbide particles (for example, silicon carbide), alumina, mullite or borides having a size d50 of between 0.1 pm and 2 pm. The binder and / or plasticizer are, for example, polyvinyl alcohol (PVA), polyethylene glycol (PEG), glycerol, polyvinylpyrrolidone (PvP) or other organic binders such as soaps or oils. The plasticizer is, for example, polyethylene glycol 200 (PEG 200).

[0068] Regardless of the embodiment, the textile preform may be made entirely or in part by stacking layers or plies obtained by two-dimensional (2D) weaving. The preform may also be made entirely or in part by three-dimensional (3D) weaving. By two-dimensional weaving, here is meant a conventional weaving method by which each weft thread passes from one side to the other of the threads of a single warp layer or vice versa. By three-dimensional weaving, here is meant a weaving for which warp threads pass through several layers of weft threads, or weft threads pass through several layers of warp threads.

[0069] The textile preform can also be made entirely or in part from sheets of unidirectional fibers, which can be obtained by automatic placement of fibers, or by filament winding.

[0070] The textile preform can also be made from fibers made of the following materials: alumina, mullite, silica, an aluminosilicate, a borosilicate, silicon carbide, carbon, or a mixture of several of these materials.

[0071] In the example of Figures 1 and 2, a textile preform of constant thickness was placed in the impregnation chamber of the infiltration tool of the invention. It is however possible to place a textile preform of variable thickness as shown in Figures 4A, 4B, 4C, 4D and 4E, these figures representing the impregnation of the slip over time in the textile preform according to the method of the invention implemented in an infiltration tool of the invention.

[0072] The preform 410 has a variable thickness between a maximum thickness Emax and a minimum thickness Emin. It is arranged in an infiltration tool 400 according to the invention which comprises a circulation grid 460, which corresponds to the part made of porous material 160, 260 of FIGS. 1 and 2. The thickness E460 of the circulation grid 460 is small compared to the variation in thickness of the preform 410. For example, the textile preform 410 has a thickness varying between 0.5 mm and 8 mm, while the circulation grid 460 has a thickness E460 of between 0.5 mm and 3 mm.

[0073] As explained previously, the slip enters the impregnation chamber of the tool 400 from the inlet port 411 and circulates to the outlet port 412 under a circulation pressure PL. The slip will infiltrate the textile preform 410 and its liquid phase is filtered and eliminated by the outlet vent 432. The circulation of the slip from the inlet port 411 to the outlet port 412, its infiltration into the preform 410 and the elimination of its liquid phase are symbolized in FIGS. 4B, 4C, 4D and 4E by the different arrows. The liquid phase removal pressure of the slip at the outlet vent 432 is lower than the circulation pressure of the slip between the inlet 411 and outlet 412 ports. As explained previously, this ensures good circulation of the slip in the entire preform 410 and the impregnation chamber. Thus, the particles or powder of the slip do not stagnate at the level of the hollows 480 or the bumps 490 of the textile preform 410 and are distributed throughout the entire preform 410.

[0074] The expression “between ... and ...” must be understood as including the limits.

Claims

Claims

1. Infiltration tool (100, 200, 400) for a slip (120, 220) in a textile preform (110, 210) comprising: - a mold (102, 202) which comprises an impregnation chamber (103, 203) comprising on one of its faces a filtration element (130, 230) for a liquid phase (131, 231) of the slip intended to receive a first face (113, 213) of a textile preform (110, 210, 410), the impregnation chamber being closed by a counter-mold (101, 201) located opposite the filtration element;and - an outlet vent (132, 232, 432) present on the mold and configured to remove a filtrate (131, 231) from the filtration element at a removal pressure (P2), characterized in that the tooling also comprises a slip circulation system comprising an inlet port (141, 241, 411) and an outlet port (142, 242, 412), the circulation system being configured to circulate the slip in the impregnation chamber from the inlet port to the outlet port at a circulation pressure (PI) higher than the removal pressure (P2).;

2. Infiltration tooling (200) according to claim 1, comprising a recirculation circuit (240) connecting the outlet port (242) to the inlet port (241) such that the slip circulation system is a closed circuit.

3. Infiltration tooling according to any one of claims 1 or 2, wherein the circulation system comprises drainage means extending between the inlet port and the outlet port.

4. Infiltration tool according to claim 3, in which the drainage means comprise a piece of porous material (160, 260, 460) intended to be placed on a second face (114, 214) of the textile preform opposite the first face (113, 213).

5. Infiltration tooling according to any one of claims 3 or 4, in which the drainage means comprise channels placed or formed on an internal surface of the counter-mold and intended to be opposite the second face (114, 214) of the textile preform.

6. Infiltration tooling according to any one of claims 1 to 5, in which the inlet and outlet ports are intended to be located opposite a lateral face (111, 211, 112, 212) of the textile preform.

7. Infiltration tooling according to any one of claims 1 to 6, wherein the inlet port is present on the countermold or on the mold and the outlet port is present on the countermold or on the mold.

8. Infiltration tooling according to any one of claims 1 to 7, also comprising a flexible membrane intended to be located between the counter-mold and the textile preform.

9. A method of infiltrating (300) a slip into a textile preform implemented in an infiltration tool according to any one of claims 1 to 8, the method comprising: - placing (310) a textile preform in the impregnation chamber by resting one of the faces of the preform on the filtration element and closing the infiltration tool by placing the counter-mold on the textile preform, and - infiltrating (320) the textile preform with a slip by circulating the slip in the impregnation chamber from the inlet port to the outlet port under a circulation pressure (PI) while filtering and eliminating a liquid phase of the slip through the filtration element and the outlet vent under an elimination pressure (P2) lower than the circulation pressure (PI).

10. Infiltration method according to claim 9, wherein the pressure difference (AP) between the circulation pressure (PI) and the elimination pressure (P2) is between 1.105 Pa and 20.105 Pa.

11. An infiltration method according to any one of claims 9 or 10, wherein the slip exiting the outlet port is reintroduced into the impregnation chamber through the inlet port.

12. An infiltration method according to any one of claims 9 to 11, wherein the circulation rate of the slip in the circulation system is at least twice the filtration rate of the liquid phase of the slip by the filtration element and the outlet vent.

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