Holding tooling for the manufacture of a ceramic matrix composite part

Abstract

Holding tooling for the manufacture of a ceramic matrix composite part Holding tooling for the manufacture of a ceramic matrix composite part, the ceramic matrix composite part being formed from an impregnated preform, the impregnated preform comprising a portion (100) extending along an axis (Δ), and the portion having a circular cross-section along a section plane perpendicular to the axis, the circular cross-section, the tooling comprising at least one clamping element (10; 20) configured to hold the impregnated preform by clamping at the level of the circular cross-section portion of the impregnated preform during a CMC part formation step exposing the impregnated preform to a temperature above 1050°C, the clamping element having a split ring shape, an inner diameter (T1) and an outer diameter (T2), and comprising a slot (12;22), the slot representing an angular opening of the split ring shape from 1° to 20°. Figure for the abbreviation: Fig. 2.;

Description

Title of the invention: Holding tool for the manufacture of a ceramic matrix composite part Technical field

[0001] The present disclosure relates to a holding tool for the manufacture of ceramic matrix composite parts. In particular, the present tool is suitable for the manufacture of composite parts for aircraft engines. Prior art

[0002] Ceramic matrix composite parts, or CMC parts, are manufactured from impregnated preforms comprising a fibrous preform impregnated with ceramic matrix precursors. More specifically, the impregnated preforms are densified during densification steps to obtain finalized CMC parts. The densification steps may involve one or more treatment steps at high temperatures, generally above 1000°C. This is the case when the impregnation of the fibrous preform is carried out by liquid means and is followed by pyrolysis (in particular for the densification of SiC / SiC type CMCs obtained by a PIP method, an acronym for polymer impregnation and pyrolysis). In other cases, the densification may include sintering (in particular for the densification of oxide-oxide type CMCs).

[0003] During these processing steps, the ceramic matrix precursor may no longer sufficiently hold the impregnated preform, which may cause deformations of the impregnated preform. These deformations of the impregnated preform occurring during the high-temperature processing steps may affect the geometry of the final CMC part. Under these circumstances, the final CMC part exhibits deformations that are not acceptable. This problem concerns both SiC / SiC composites and oxide-oxide composites.

[0004] Few solutions exist to counteract this tendency of fiber preforms to deform during high-temperature processing steps. Known solutions consist of increasing the thickness of the parts or integrating stiffeners. However, this complicates the design and production of the parts. In addition, such parts are heavier, which is a constraint for aeronautical parts. Also, the quantity of raw material to be used to make such parts is greater, which proportionally increases the costs.

[0005] Furthermore, the larger, thinner and slender the parts to be obtained, the more problematic the deformation phenomenon is. Consequently, it is difficult to obtain composite parts with a slender shape (as is the case for certain aircraft parts) with a characteristic dimension greater than ten centimeters.

[0006] There is therefore a need for improvement to maintain an acceptable shape of the impregnated preform when it undergoes high temperature treatment. Statement of the invention

[0007] The present disclosure relates to a holding tool for manufacturing a ceramic matrix composite part, the ceramic matrix composite part being formed from an impregnated preform comprising a hollow fiber preform and a ceramic matrix precursor, the impregnated preform comprising a portion extending along an axis, and the portion having a circular section along a section plane perpendicular to the axis, the circular section having an inside diameter and an outside diameter, the tool comprising at least one clamping element configured to hold the impregnated preform by clamping at the circular section portion of the impregnated preform during a step of forming the ceramic matrix composite part exposing the impregnated preform to a temperature above 1050°C, the clamping element having a split ring shape, an inside diameter and an outside diameter, and comprising a slot,the slot representing an angular opening of the split ring shape from 1° to 20°. ,

[0008] It is understood here that the split ring shape is a revolution shape having a height, and in which a slot extends over the entire height of the revolution shape.

[0009] It is understood that the angular opening is measured when the clamping element is free and detached from the impregnated preform.

[0010] Such tooling maintains the impregnated preform during the high temperature step, which makes it possible to reduce or even eliminate deformations of the impregnated preform that may appear during said step. In particular, this makes it possible to maintain the shape of the impregnated preform in the case where the ceramic matrix precursor is no longer sufficient to ensure the maintenance of the impregnated preform during the heat treatment.

[0011] The slot of the clamping elements provides elasticity which makes it possible to enlarge or reduce the opening by applying a stress to the clamping element. This elasticity allows, for example, the clamping element to "clip" onto the impregnated preform and hold it, without applying excessive stresses which could damage the impregnated preform or create defects in it.

[0012] “Elasticity” means the ability of the clamping element to deform reversibly, without deteriorating or plasticizing.

[0013] “Clip-on” means a method of assembling the impregnated preform and the clamping element by engagement and elastic deformation. Here, it is the clamping element which engages and deforms elastically to “clip” onto the impregnated preform. When the clamping element is engaged in the “clipped” position, it has a lesser elastic deformation than the elastic deformation necessary for engagement. When the impregnated preform and the clamping element are engaged with each other in the “clipped” position, they cooperate with each other so as to oppose their relative movements in the direction of disengagement (direction opposite to the direction of engagement). In the “clipped” position, they can also cooperate so as to oppose their relative movements in the direction of the extension of the engagement, beyond the “clipped” position. The elasticity of the clamping element allows it to be “clipped” onto the impregnated preform, which makes it capable of cooperating with said impregnated preform.

[0014] This tooling is particularly suitable for SiC / SiC and oxide-oxide preforms. In the case of a SiC / SiC preform, the tooling is particularly relevant during the pyrolysis of the first PIP cycles.

[0015] In some embodiments, the tooling comprises a plurality of clamping elements.

[0016] Using multiple clamping elements improves the holding of the impregnated preform. In addition, the tooling may provide different clamping elements to adapt to the geometry of the impregnated preform.

[0017] In certain embodiments, the inner diameter of the clamping element is greater than 120 mm, preferably greater than 400 mm, more preferably greater than 500 mm.

[0018] In this configuration, the clamping element is capable of holding large fiber preforms, which therefore makes it possible to manufacture large CMC parts.

[0019] In some embodiments, the clamping element is a single piece.

[0020] In this configuration, the clamping element is easier to produce, which represents a saving in time and cost.

[0021] In some embodiments, the clamping member is configured to be releasably clamped to the preform.

[0022] “Removable” means that it is possible to separate the clamping element from the impregnated preform without the aid of special tools.

[0023] Thus, the clamping element is reusable for the formation of other ceramic matrix composite parts. This also makes it easier to use. For example, the tooling can, for each PIP cycle, be installed after impregnation, but before pyrolysis, and then removed at the end of said pyrolysis.

[0024] In addition, this represents a saving in cost and mass compared to solutions known, involving for example stiffeners.

[0025] In certain embodiments, the angle of the opening is preferably between 1° and 10°, and even more preferably between 3° and 4°.

[0026] These preferred ranges make it possible to improve the compromise between the strength of the clamping element and its elasticity. Furthermore, these preferred configurations make it possible to ensure that the slot is wide enough for the clamping element to be able to cooperate by clipping with the impregnated preform.

[0027] In certain embodiments, two clamping elements following one another in the direction of the axis are at most 250 mm apart, preferably 100 mm.

[0028] In this configuration, the maintenance of the impregnated preform is improved, which further reduces the appearance of defects during treatment of the preform at high temperature.

[0029] In some embodiments, at least one clamping element of the tooling is configured to be disposed around the circular section portion of the impregnated preform, and wherein, for each section perpendicular to the axis of the impregnated preform on which the at least one clamping element is configured to hold the impregnated preform, the inner diameter of the clamping element is less than the outer diameter of the circular section of the impregnated preform.

[0030] In this configuration, the clamping element is easy and inexpensive to produce. Furthermore, this configuration facilitates the installation of the clamping element. In addition, when the clamping element is clamped against the impregnated preform, the opening of the clamping element is slightly spaced apart from its equilibrium spacing, when the clamping element is free. Under these circumstances, the clamping element applies a slight internal radial stress to the impregnated preform, which ensures better fixing of the clamping element and better retention of the impregnated preform.

[0031] In some embodiments, the inner diameter of the clamping element is 0.1 to 0.5% less than the outer diameter of the circular section of the impregnated preform.

[0032] This preferred configuration makes it possible to improve the fixing of the clamping element and the holding of the impregnated preform. In addition, when these proportions are respected, the resulting holding of the clamping element is less likely to create defects in the impregnated preform.

[0033] In some embodiments, at least one clamping element of the tooling is configured to be disposed within the circular section portion, and wherein, for each section perpendicular to the axis of the impregnated preform on which the at least one clamping element is configured to hold the impregnated preform, the outer diameter of the clamping element is less than the diameter inside the circular section of the impregnated preform.

[0034] This configuration represents an alternative for fixing the clamping element to the impregnated preform and may prove relevant for certain impregnated preform configurations. A clamping element made of composite material is able to withstand any stress caused by the removal of the part held during sintering.

[0035] In the case where the tooling comprises a plurality of clamping elements, certain clamping elements may be provided inside the impregnated preform while others may be fixed by clipping.

[0036] Furthermore, when the clamping element is inside the impregnated preform, the opening of the clamping element is slightly compressed relative to its equilibrium spacing, when the clamping element is free. Under these circumstances, the clamping element applies a slight external radial stress on the impregnated preform, which ensures better fixing of the clamping element and better holding of the impregnated preform.

[0037] In some embodiments, the outer diameter of the clamping element is 0.1 to 0.5% greater than the inner diameter of the circular section of the impregnated preform.

[0038] This preferred configuration makes it possible to improve the fixing of the clamping element and the holding of the impregnated preform. In addition, when these proportions are respected, the holding provided by the clamping element is less likely to create defects in the impregnated preform. This configuration is particularly effective in avoiding local compaction of the impregnated preform, which can create areas on the impregnated preform where the fiber content is higher than elsewhere.

[0039] In some embodiments, the clamping element is provided in the same material as the ceramic matrix composite part to be obtained.

[0040] It is understood that such a clamping element has been sintered / pyrolyzed before its use in a tool according to this embodiment.

[0041] Thus, the thermal expansion of the clamping element is comparable to the thermal expansion of the impregnated preform, which makes it possible to improve the retention of the impregnated preform by the clamping element during the high temperature forming step.

[0042] In some embodiments, the split ring shape of at least one clamping element of the tooling is a conical shape.

[0043] In this configuration, the tooling can adapt to conical-shaped fiber preforms.

[0044] In some embodiments, the split ring shape of at least one clamping element of the tooling is an annular shape.

[0045] In this configuration, the clamping element is simpler to produce. In the case where the tooling comprises several clamping elements, each clamping element may have a different shape from the other clamping elements. For example, one of the clamping elements may have an annular shape while another has a conical shape.

[0046] The present disclosure further relates to a method for manufacturing a ceramic matrix composite part from an impregnated preform comprising a fibrous preform and a ceramic matrix precursor, the method comprising a forming step in which the impregnated preform is exposed to a temperature above 1050°C, and in which a tool according to one of the preceding embodiments is used.

[0047] Such a method has all the advantages mentioned above. This applies particularly to sintering or pyrolysis steps for the formation of CMC parts of the SiC / SiC or oxide-oxide type.

[0048] The above-mentioned characteristics and advantages, as well as others, will appear on reading the detailed description which follows, of exemplary embodiments of the proposed device and method. This detailed description refers to the attached drawings. Brief description of the drawings

[0049] The attached drawings are schematic and are intended primarily to illustrate the principles of the disclosure.

[0050] [Fig-1] [Fig.l] represents a clamping element according to a first mode of realization lization.

[0051] [Fig.2] [Fig.2] represents a clamping element according to the embodiment of [Fig.l] clamped around an impregnated preform.

[0052] [Fig.3] [Fig.3] represents a clamping element according to the embodiment of [Fig.l] clamped inside the impregnated preform.

[0053] [Fig.4] [Fig.4] represents a clamping element according to a second embodiment. Description of the embodiments

[0054] In order to make the disclosure more concrete, an example of a device is described in detail below, with reference to the attached drawings. It is recalled that the invention is not limited to this example.

[0055] [Fig.l] represents a first embodiment of a clamping element 10 of a tool according to the present invention. The clamping element 10 has a split ring shape and therefore comprises a slot 12, present over the entire height of the clamping element 10. The clamping element 10 has an annular revolution shape with an inner diameter T1 and an outer diameter T2 when the clamping element 10 is free. Subsequently, the inner diameter Tl and the outer diameter T2 will refer to the dimensions of the free clamping element 10. Typically, the inner diameter Tl is between 100 mm and 1100 mm, and the outer diameter T2 is larger than Tl by 10 mm to 40 mm. These dimensions are adjusted to cooperate with the part held by the tooling.

[0056] The slot 12 represents an opening of the clamping element 10 by an angle a of between 1° and 20°. In the present example, the angle a is 3°. Furthermore, in the present example, the clamping element 10 is provided in Cerasep ® A100 for an impregnated preform of the oxide-oxide type and is provided in Sepcarbinox ® for an impregnated preform of the SiC / SiC type. It is understood that the split ring is obtained by forming a non-split ring having the inner diameter T1 and the outer diameter T2 and that a portion of the ring is then removed over the entire height of the ring to form the slot. The non-split ring can be taken from a flat plate or taken from a tube having the appropriate dimensions.

[0057] In the present disclosure, it is understood that the clamping element 10 is “spread” when it undergoes a stress which tends to increase the angle α. Conversely, it is understood that the clamping element 10 is “compressed” when it undergoes a stress which tends to decrease the angle α. The clamping element remains in the elastic domain as long as the angle α is between 1° and 5°.

[0058] [Fig. 2] shows a clamping element 10 according to the embodiment of [Fig. 1] clamped around an impregnated preform comprising an impregnated preform and a ceramic matrix precursor. For example, this ceramic matrix precursor can be configured to obtain a CMC part of the SiC / SiC type or of the oxide-oxide type.

[0059] The impregnated preform comprises a hollow cylindrical portion 100 extending along an axis A. The portion 100 has a circular section in a section plane perpendicular to the axis A. This circular section has an inner diameter DI and an outer diameter D2 when the portion 100 is free. Subsequently, the inner diameter DI and the outer diameter D2 will refer to the dimensions of the free portion 100. Typically, the inner diameter DI measures 380 mm and the outer diameter D2 measures 394 mm.

[0060] The clamping element 10 is clamped around the portion 100 of the impregnated preform, in a plane perpendicular to the axis A. There is therefore contact between the inner circumference of the clamping element 10 and the outer circumference of the portion 100. In the present example, the inner diameter T1 of the clamping element 10 is smaller than the outer diameter D2 of the portion 100.

[0061] The clamping element 10 is clipped onto the portion 100. To clip the clamping element 10 to the portion 100, the clamping element 10 is elastically moved apart by opening the slot 12 by increasing the angle a, so that the clamping element 10 can be arranged around the portion 100.

[0062] Once positioned, the clamping element 10 tends to compress elastically around the portion 100 to return to its equilibrium position. Since the inner diameter T1 of the clamping element 10 is smaller than the outer diameter D2 of the portion 100, equilibrium is never perfectly achieved for the clamping element 10. Under these circumstances, a slight pressure is applied by the clamping element 10 to the impregnated preform.

[0063] Under these circumstances, the clamping element 10 follows the shrinkage of the impregnated preform when the latter undergoes a high-temperature forming step. The circular section of the impregnated preform is therefore retained throughout the high-temperature forming step, in which the ceramic matrix precursor gradually transforms into a ceramic matrix.

[0064] [Fig. 3] represents a clamping element 10 according to the embodiment of [Fig. 1] clamped inside the impregnated preform.

[0065] The clamping element 10 is clamped inside the portion 100 of the impregnated preform, in a plane perpendicular to the axis A. There is therefore contact between the outer circumference of the clamping element 10 and the inner circumference of the portion 100. In the present example, the outer diameter T2 of the clamping element 10 is larger than the inner diameter DI of the portion 100.

[0066] The clamping element 10 is inserted inside the portion 100. To insert the clamping element 10 into the portion 100, the clamping element 10 is elastically compressed by closing the slot 12 by decreasing the angle a, so that the clamping element 10 can be inserted inside the portion 100.

[0067] Once positioned, the clamping element 10 tends to move away elastically inside the portion 100 to return to its equilibrium position. Since the outer diameter T2 of the clamping element 10 is larger than the inner diameter DI of the portion 100, equilibrium is never perfectly achieved for the clamping element 10. Under these circumstances, a slight pressure is applied by the clamping element 10 to the impregnated preform.

[0068] [Fig. 4] shows a clamping element 20 according to a second embodiment. The clamping element 20 has a conical split ring shape and therefore comprises a slot 22. The clamping element 20 therefore has a conical revolution shape, comprising a height. For a section perpendicular to the axis of the conical shape, the clamping element 20 has a circular section having an inner diameter and an outer diameter. Due to the conical shape, when the clamping element 20 is placed on its largest circular section, the inner and outer diameters of the clamping element 20 decrease as one travels along the height of the clamping element 20 from bottom to top, i.e. from the circular section having the largest inner diameter to the circular section having the smallest inner diameter. The slot 22 is continuous between the circular section having the largest inner diameter and the circular section having the smallest inner diameter. In this exemplary embodiment, the slot 22 represents, as in the first embodiment, an angular opening of the conical shape of the clamping element 20.

[0069] The clamping element 20 is configured to cooperate with portions of fiber preforms which have a conical shape similar to the shape of the clamping element 20. In a manner similar to the first embodiment, the portion extends along an axis A, and has a circular section for a section plane perpendicular to the axis A. The operation of the clamping element 20 is identical to the operation of the clamping element 10 of the first embodiment.

[0070] In particular, the clamping element 20 can be clipped around the portion of the impregnated preform according to the same method as the first embodiment. In this case, for each section perpendicular to the axis A of the portion, the inner diameter of the clamping element 20 is smaller than the outer diameter of the portion. It is then understood that the portion of the impregnated preform is constrained over the entire height of the clamping element 20.

[0071] The clamping element 20 can also be inserted inside the portion of the impregnated preform according to the same method as the first embodiment. In this case, for each section perpendicular to the axis A of the portion, the outside diameter of the clamping element 20 is larger than the inside diameter of the portion. It is then understood that the portion of the impregnated preform is constrained over the entire height of the clamping element 20.

[0072] The tooling of the present invention may comprise a plurality of clamping elements 10, 20 of annular and / or conical shape configured to be arranged on the same impregnated preform. It is then understood that the tooling may comprise either a plurality of clamping elements that are solely annular, or a plurality of clamping elements that are solely conical, or a plurality of clamping elements some of which are annular and others of which are conical.

[0073] These clamping elements 10, 20 may be arranged inside and / or around the impregnated preform. It is then understood that the tooling may comprise either a plurality of clamping elements only inside the impregnated preform, or a plurality of clamping elements only around the impregnated preform, or a plurality of clamping elements some of which are inside the impregnated preform and others are around the impregnated preform.

[0074] Furthermore, in the case of the preparation of an oxide-oxide CMC part, a layer sintering inhibition layer may be provided on the surface of the clamping element 10, 20 in contact with the held part. This layer ensures that the clamping element 10, 20 and the part do not weld at high temperature. For example, this layer may be zirconia powder or an adhesive that degrades at high temperature.

[0075] The present tooling has been described for forming a ceramic matrix composite part but could be used for forming any cylindrical part that includes a high temperature forming step.

[0076] Although the present invention has been described with reference to specific exemplary embodiments, it is obvious that modifications and changes may be made to these examples without departing from the general scope of the invention as defined by the claims. In particular, individual features of the various illustrated / mentioned embodiments may be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than restrictive sense.

[0077] It is also obvious that all the characteristics described with reference to a method are transposable, alone or in combination, to a device, and conversely, all the characteristics described with reference to a device are transposable, alone or in combination, to a method.

Claims

Claims

1. Holding tooling for manufacturing a ceramic matrix composite part, the ceramic matrix composite part being formed from an impregnated preform comprising a hollow fiber preform and a ceramic matrix precursor, the impregnated preform comprising a portion (100) extending along an axis (A), and the portion (100) has a circular section along a section plane perpendicular to the axis (A), the circular section having an inner diameter (D1) and an outer diameter (D2), the tooling comprising at least one clamping element (10; 20) configured to hold the impregnated preform by clamping at the circular section portion (100) of the impregnated preform during a step of forming the ceramic matrix composite part exposing the impregnated preform to a temperature above 1050°C, the clamping element (10;20) having a split ring shape, an inner diameter (T1) and an outer diameter (T2), and comprising a slot (12; 22), the slot (12; 22) representing an angular opening of the split ring shape of 1° to 20°, and wherein the split ring shape of at least one clamping element (10, 20) of the tooling is a conical shape.;

2. Tooling according to claim 1, wherein at least one clamping element (10; 20) of the tooling is configured to be arranged around the portion (100) with circular section of the impregnated preform, and wherein, for each section perpendicular to the axis (A) of the impregnated preform on which the at least one clamping element (10; 20) is configured to hold the impregnated preform, the inner diameter (T1) of the clamping element (10; 20) is less than the outer diameter (D2) of the circular section of the impregnated preform.

3. Tooling according to claim 2, wherein the inner diameter (T1) of the clamping element is 0.1 to 0.5% less than the outer diameter (D2) of the circular section of the impregnated preform.

4. Tooling according to one of claims 1 to 3, in which at least one clamping element (10; 20) of the tooling is configured to be arranged inside the portion (100) with circular section, and in which, for each section perpendicular to the axis (A) of the

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9. impregnated preform on which the at least one clamping element (10; 20) is configured to hold the impregnated preform, the outer diameter (T2) of the clamping element (10; 20) is less than the inner diameter (Dl) of the circular section of the impregnated preform. Tooling according to claim 4, wherein the outer diameter (T2) of the clamping element is 0.1 to 0.5% greater than the inner diameter (Dl) of the circular section of the impregnated preform. Tooling according to one of claims 1 to 5, in which the clamping element (10; 20) is provided in the same material as the ceramic matrix composite part to be obtained. Tooling according to one of claims 1 to 6, wherein the split ring shape of at least one clamping element (10; 20) of the tooling is an annular shape. Tooling according to one of claims 1 to 7, wherein the tooling comprises a plurality of clamping elements (10, 20). Tooling according to claim 8, in which two clamping elements (10, 20) following one another in the direction of the axis (A) are at most 250 mm apart, preferably 100 mm.

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