Tool for a multi-layer board with semi-forced flow

Abstract

The present invention relates to a method for densifying a porous annular substrate (21) having a central channel (21a) by vapor phase chemical infiltration, the method comprising at least the following steps: providing a stack (20) of porous annular substrates (21), providing a plurality of individual modules (30), which comprise a stack (20) arranged on a support plate (31), the support plate (31) comprising perforated injection tubes (33), each injection tube being mounted on a gas inlet opening (32), forming a stack of individual modules. Aligning the stack of individual modules (30) in a sealed manner using an annular seal (35), said annular seal (35) being arranged between the injection tube (33) of a second individual module (30b) and the gas inlet opening (32) of a first individual module (30a) cooperating therewith, injecting into the internal volume (24) of each stack (20) of porous annular substrates (21) a gas phase containing a gaseous precursor of a matrix material to be deposited in the pores of the substrate (21).

Description

Technical Field

[0001] The present invention relates to the production of composite parts comprising a porous annular substrate densified by chemical vapor infiltration (CVI), and more particularly to the production of parts having a central channel.

[0002] The present invention applies particularly but not exclusively to the production of annular brake discs or divergent nozzles for rocket engines made of thermostructural composite materials. Background Art

[0003] Thermostructural composite materials are known for their excellent mechanical properties and their ability to retain these properties at high temperatures. Typical examples of thermostructural composite materials are carbon-carbon (C-C) composite materials and ceramic matrix composite materials (CMC), the carbon-carbon (C-C) composite materials comprising a porous reinforcement substrate of carbon fibers densified by a carbon matrix and the ceramic matrix composite materials (CMC) comprising a porous reinforcement substrate (such as silicon carbide) of refractory fibers (such as carbon or ceramic) densified by a ceramic matrix.

[0004] C-C composite materials are generally used for the production of aircraft brake discs due to their high-energy tribological properties, non-brittle nature, thermal properties (conductivity and heat capacity) and their density.

[0005] The densification of a porous substrate by chemical vapor infiltration (CVI) consists in placing an annular preform in the reaction chamber of an infiltration device and introducing a gas phase into the chamber, one or more components of the gas phase forming precursors of the matrix material, which are deposited inside the substrate to ensure its densification. The infiltration conditions are selected, in particular the composition and flow rate of the gas phase and the temperature and pressure in the chamber, to allow the gas phase to diffuse inside the accessible internal pores of the substrate and to cause the deposition of the desired material therein by decomposition of the gas-phase components or by reaction between several components. Document FR 2834713 describes such a method and the device for its implementation.

[0006] The chemical vapor infiltration conditions for pyrolytic carbon or thermodecomposed carbon have long been known to those skilled in the art. The carbon precursors are alkanes, alkyls or alkenes, generally propane, methane or a mixture of both. The infiltration is carried out for example at a temperature of about 1000 °C and a pressure of about 1 kPa.

[0007] The gas phase containing the precursors of the material to be deposited inside the preform is introduced at one longitudinal end of the reaction chamber, while the residual gas is evacuated by suction at the opposite end.

[0008] When it is necessary to densify a large stack of substrates, large devices are generally used. Figure 1 A known example of a disk load that can be used in a reaction chamber commonly called a "densification furnace" is shown.

[0009] Chamber 1 is cylindrical about axis X. The load consists of a stack of a plurality of porous annular substrates 2 carried by the same lower support plate 3. Each stack extends in the form of a column and is formed by a plurality of stacked stack parts 4, and the stacks are separated by an intermediate support plate 5 common to all the stacks. Plates 3 and 5 include openings aligned with the central channels of the substrates 2 to cause the reactive gas phase to circulate in each stack, and then the reactive gas phase will pass through the substrates 2 to densify them. The base cover forms an upper plate 6 placed at the top of the load and encloses the internal volume of each stack (R1). The intermediate support plate 5 is maintained using vertical rods 7.

[0010] The industrial means incorporating CVI, as well as the high-temperature treatment workshops for carbonizing or heat-treating the annular preforms and heat-treating the partially or fully densified blanks, are organized around plates including 1 to several stacks (usually 8 to 19 stacks), depending on the size of the room and the size of the furnace. These plates are moved by an overhead crane with slings. They are also stored in racks or stackers and then brought to the respective workshops (furnace loading, density control, etc.).

[0011] Figure 1 is a schematic diagram of the hot zone of a directed flow load. As Figure 2 shown, it shows a Figure 1 cross-sectional view of the densification furnace, and this hot zone includes from its bottom to its top: an inlet 8 for the reactive gas mixture, then a preheating zone 9 capable of raising the temperature of the gas to the densification temperature, and finally a load zone 10. At the top of the furnace, at the level of the base cover 11, a chimney 12 is installed in the cover 11, and the waste gas generated by the deposition reaction is discharged through the chimney 12.

[0012] The load consists of N1 plates, labeled P1 to PN, and each plate supports N2 stacks of a plurality of porous annular substrates 2, and the stacks are labeled S1 to SN. The number of plates and the number of stacks are related to the size of the furnace and the size of the discs (i.e., the porous annular substrates 2).

[0013] On each plate, there are stacks of discs 2 separated by separators 13, and each stack terminates at its top with a cover disc 14 that limits leakage. At the bottom of each stack, there is a collar 15 that abuts against the cover disc 14 of the lower stack. This collar 15 enables the height difference between the stacks to be compensated by sliding. Finally, rods 7 are installed between the stacks S1 to SN, and they are used to bear the mass of the upper plates P2 to PN.

[0014] The gas at the end of the preheating zone 9 enters each column formed by the stack S1 to SN of disks 2. The gas flows from the inside to the outside of the disk column, through the leaks formed by the pores of each preform 2, through the gaps created between the disks 2 by the spacers 13, and through the channels between the channels (P1 to PN) between the plates 3 and 5. At the position of the sliding gap of the ferrule, the ferrule 15 leaks gas through its sliding.

[0015] Document FR 2 821 859 discloses a densification method for chemically vapor infiltrating a porous substrate by, in particular, using a semi-forced flow. To adapt to the semi-forced flow described in this document, it is necessary to control the leakage between the disks and also the leakage at the channels between the plates. The last point is the most difficult because the heights of the disk stacks are not the same. And in the case where the sealing at the top of each stack lacks good control, the pressure difference required to force the gas into the pores of the disks 2 cannot be obtained.

[0016] It is also known from patent FR 3 084 892 that a gas distributor is used instead of a rod, which makes it possible to simultaneously perform the function of bearing the load (the function previously provided by the rod), guiding the gas (cold), which avoids the cooling of the disks and the gas distribution at the preform level. Summary of the Invention

[0017] The object of the present invention is to provide a rich technical solution for implementing pressure gradient densification, which enables to improve the distribution of the reaction gas in the load zone of the densification furnace and generally to reduce the densification gradient between the substrates located at different positions in the load zone without affecting the load capacity of the furnace and even to increase the load capacity of the furnace.

[0018] An object of the present invention proposes a densification method for densifying a porous annular substrate having a central channel by pressure gradient chemical vapor infiltration, the method at least comprising the following steps:

[0019] - Providing a stack of a plurality of porous annular substrates, each stack including an internal volume formed by the central channels of the stacked substrates,

[0020] - Providing a plurality of individual modules, each individual module including a support plate and a stack of porous annular substrates arranged on the support plate, and for each stack, the support plate includes a gas inlet opening leading to the internal volume,

[0021] - Forming a stack of the individual modules in the chamber of the densification furnace, each first gas inlet opening of the support plate of the first individual module mounted on the second individual module communicating with the internal volume of one of the stacks of the second individual module so as to allow the gas to flow between the individual modules, and

[0022] - Injecting a gas phase of a gaseous precursor containing a matrix material to be deposited within the pores of a substrate into the internal volume of each stack of porous annular substrates.

[0023] According to a general feature of the present invention, for each second separate module covered by a first separate module, each stack includes at least one cover ring, a sealing ring, and a deformable annular seal; the cover ring is supported on top of the stack of porous annular substrates by an annular separator, the sealing ring is arranged around the annular separator in a plane perpendicular to the direction of the stack of porous annular substrates; the deformable annular seal is provided between at least one cover ring and a support plate of the first separate module.

[0024] The at least one cover ring forms a cover supported on top of the stack by an annular separator. The function of the cover of the stack and the associated sealing ring is to seal the stack, thereby reducing gas leakage. Thus, the cover and the deformable annular seal are capable of strengthening the seal between the support plate of the upper separate module and the cover.

[0025] Additionally, if a stack is lower than one or more other stacks of the same separate module, the stack in question may include several superimposed covers to compensate for the lack of height.

[0026] The separator is capable of maintaining a space between the porous annular substrates, thereby increasing the surface in direct contact with the gas. Additionally, the sealing ring thus arranged between the annular substrates enables avoiding radial leakage between the porous annular substrates and thus maximizing the amount of gas passing through the porous annular substrates. The sealing ring is preferably provided at the radial outer periphery of the porous annular substrate. The sealing ring is made of, for example, Inconel.

[0027] In an exemplary embodiment, each deformable annular seal may be arranged to be capable of undergoing deformation according to the direction of the stack of porous annular substrates, the deformation being greater than or equal to the thickness of the cover ring, for example 3 millimeters. Additionally, each deformable annular seal has a thermal resistance against, for example, a temperature of 1100 °C.

[0028] The deformable annular seal may be made of a woven fabric or cord of expanded graphite or carbon fiber or ceramic fiber.

[0029] In an exemplary embodiment, each stack may include at least three legs that extend from a cover plate towards a support plate along the direction in which the porous annular substrates are stacked, and the stack is arranged on the support plate.

[0030] Ideally, the seal is made of a material that is more deformable than the porous annular substrates of the stack. The three legs hanging from the cover enable avoiding the opposite possibility: the deformation of the porous annular substrates is thus restricted by the three legs hanging from the cover, and they form a load support system.

[0031] Advantageously, for each stack, each individual module may include an injection tube that is mounted on the gas inlet opening and extends within the internal volume of the stack between a first tube end connected to the support plate and a free second tube end. The injection tube further includes gas injection holes leading to the internal volume. Each gas inlet opening of the support plate of the first individual module mounted on the second individual module communicates with one of the second ends of the injection tubes of the second individual module so that gas can circulate between the individual modules.

[0032] In an exemplary embodiment, each support plate may include a first surface on which the stack is disposed and a second surface opposite the first surface. Each gas inlet opening may have a frustoconical shape with a first diameter and a second diameter. The first diameter is formed in the second surface of the support, and the second diameter is smaller than the first diameter and is formed in the first surface of the support plate or between the first and second surfaces of the support plate. And the second end of each injection tube may include a complementary frustoconical shape that mates with the frustoconical shape of the gas inlet opening.

[0033] Thus, the injection tube forms a convex centering tool and the gas inlet opening forms a concave centering tool, which cooperate together to ensure that the individual modules are correctly centered with respect to each other.

[0034] Advantageously, the method may further include the step of hermetically aligning the individual modules of the stack. The second end of each injection tube is inserted into the gas inlet opening of the first individual module. And for each injection tube, the first individual module further includes: an annular tube seal disposed between the second end of the injection tube of the second individual module and the cooperating gas inlet opening of the first individual module.

[0035] Thus, the present invention makes it possible to improve the gas distribution in the furnace chamber and is beneficial to the installation of a dense furnace. The sealing between the two modules provided by the annular tube seal is obtained by individual gravity during the furnace load.

[0036] The annular tube seal may be made of a woven fabric or cord of expanded graphite or carbon fiber or ceramic fiber.

[0037] In an exemplary embodiment, each injection tube may include a main tube portion forming a shoulder having a frustoconical second end, and the shoulder allows the annular tube seal to deform in a plane perpendicular to the stacking direction of the porous annular substrates.

[0038] In an exemplary embodiment, the annular tube seal preferably has a frustoconical shape to adapt to the shape of the second end of the injection tube and the gas inlet opening.

[0039] In an exemplary embodiment, for each injection tube, each support plate may include a centering ring that is centered on the gas inlet opening and shaped to accommodate the shape of the injection tube.

[0040] Accordingly, the centering ring facilitates and optimizes the assembly of the injection tube on the support plate.

[0041] In an exemplary embodiment, each porous annular substrate may comprise carbon.

[0042] In an exemplary embodiment, each porous annular substrate may form a fiber brake disc preform.

[0043] In an exemplary embodiment, each first porous annular substrate is supported on a second porous annular substrate or on a support plate by an annular spacer and a sealing ring surrounding the annular spacer, and the sealing ring provides a radial seal between the first porous annular substrate and the second porous annular substrate, or provides a radial seal between the first porous annular substrate and the support plate.

[0044] Advantageously, each individual module covered by another separate module may include a plurality of rods that extend between the support plate of the individual module and the support plate of the separate module covering it to support the mass of the at least one upper individual module.

[0045] Preferably, the height of each rod is less than the height of the stack of porous annular substrates.

[0046] In particular, the height of each rod may be less than the sum of the thickness of the deformable annular seal in each stack, the thickness of the cover ring, the thickness of one or more sealing rings, and the thickness of the stacked porous annular substrates. The thicknesses of the deformable annular seal and the sealing ring should be considered without compression. When the stack includes multiple cover rings, the thicknesses to be considered are the thicknesses of all the cover rings.

[0047] Furthermore, the height of each rod is preferably greater than the sum of the thickness of the cover ring in each stack and the thickness of the stacked porous annular substrates. When the stack includes multiple cover rings, the thicknesses to be considered are the thicknesses of all the cover rings.

[0048] In this document, height is understood as the dimension of the porous annular substrate along its stacking direction and generally corresponds to the vertical direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] What has been described Figure 1 Very schematically shows an example of a loaded porous annular substrate according to the prior art.

[0050] What has been described Figure 2 Shows Figure 1 a cross-sectional view of a densification furnace.

[0051] Figure 3 A cross-sectional view schematically showing an example of a stack of porous annular substrates according to the present invention.

[0052] Figure 4 A cross-sectional view schematically showing an example of a separate module according to the present invention.

[0053] Figure 5 A cross-sectional view showing a first example of an annular tube seal.

[0054] Figure 6 A cross-sectional view schematically showing a second example of an annular tube seal.

[0055] Figure 7 A cross-sectional view schematically showing a variant embodiment of an injection tube according to the present invention.

[0056] Figure 8 A cross-sectional view schematically showing an example of a separate module according to another embodiment of the present invention. Detailed Description

[0057] The vapor-phase chemical infiltration densification method according to the present invention first includes the following steps: during this step, a stack of a plurality of porous annular substrates processed by chemical vapor infiltration is provided.

[0058] Figure 3 A cross-sectional view showing an example of a stack 20 of porous annular substrates 21 is shown. The porous annular substrate 21 is cylindrically symmetric and along a first direction D z stack. Each porous annular substrate 21 mainly extends in a plane perpendicular to the first direction D z of. Figure 3 The cutting plane in includes the first direction D z and perpendicular to the first direction D z a second direction D R . The first direction D z coincides with the rotational symmetry axis of the porous annular substrate 21, and the second direction D R corresponds to the radial direction.

[0059] Thus, each porous annular substrate 21 of the stack 20 has an annular shape with a central channel 21a. Each porous annular substrate 21 is arranged on an annular spacer 22, the outer radial diameter of the annular spacer 22 being smaller than the outer radial diameter of the porous annular substrate 21, and the diameter of the orifice of the spacer 22 being equal to the diameter of the orifice of the porous annular substrate 21.

[0060] Each spacer 22 is in a plane perpendicular to the first direction D zIt is enclosed within a plane by a sealing ring 23. Thus, each porous annular substrate 21 abuts against the annular spacer 22 and the sealing ring 23.

[0061] The alternating stacking of the porous annular substrates 21 and the spacers 22 forms an internal volume 24 of the stack 20 at the center of the stack 20.

[0062] In addition, the stack 20 is closed at its top by an annular cover 25. The cover 25 is arranged on the stack through the annular spacer 22 and the sealing ring 23.

[0063] The method for chemically vapor infiltrating and densifying according to the present invention includes the step of providing a plurality of individual modules 30.

[0064] Figure 4 A cross-sectional view of an individual module 30 according to the present invention is schematically shown.

[0065] Each individual module 30 includes a support plate 31 and a plurality of stacks 20 of porous annular substrates 21 arranged on the support plate 30. For each stack 20, the support plate 31 includes a gas inlet opening 32 and an injection tube 33 mounted on the gas inlet opening 32. The injection tube 33 extends into the internal volume 24 of the stack 20 between a first tube end 33a connected to the support plate 31 and a free second tube end 33b.

[0066] The injection tube 33 further includes gas injection holes 34 leading to the internal volume 24.

[0067] The method for chemically vapor infiltrating and densifying according to the present invention includes the following step: during this step, a stack of individual modules 30 stacked on top of each other is formed in the chamber of a densification furnace along a first direction D z A stack of individual modules 30 stacked on top of each other.

[0068] Figure 4 The support plate 31 of the first individual module 30a to be stacked on the second individual module 30b is shown.

[0069] The step of forming a stack of individual modules 30 further includes the step of sealing and aligning the stacked individual modules 30. As Figure 4 shown, in order to achieve alignment, the second end 33b of each injection tube 33 of the second individual module 30b is inserted into the gas inlet opening 32 of the first individual module 30a.

[0070] To seal the junction between the injection tube 33 of the second separate module 30b and the intake inlet opening 32 of the first separate module 30a, for each injection tube 33, the second separate module 30a further includes an annular seal 35 that is disposed between the second end 33b of the injection tube 33 of the second separate module 30b and the gas inlet opening 32 of the first separate module 30a that mates therewith.

[0071] More particularly, each support plate 31 includes a first surface 31a and a second surface 31b opposite the first surface 31a, and the stack 20 is disposed on the first surface 31a. The gas inlet opening 32 has a frustoconical shape with a first diameter d1 and a second diameter d2, the first diameter d1 being formed in the second surface 31b of the support plate 31, and the second diameter d2 being smaller than the first diameter d1 and being formed between the first surface 31a and the second surface 31b of the support plate 31.

[0072] The second end 33b of each injection tube 33 includes a frustoconical shape complementary to the frustoconical shape of the gas inlet opening 32 such that the two frustoconical shapes fit together. The complementary frustoconical shape of the second end 33b of the injection tube 33 includes a first diameter D1 that is greater than the second diameter D2, the second diameter D2 being measured at the free distal end, while the first diameter D1 is measured at the proximal end, the proximal end being coupled to the remainder of the injection tube 33, particularly the main portion 33c.

[0073] In Figure 5 and Figure 6 two examples of the annular seal 35 are shown, which are mounted at the interface between the second end 33b of the injection tube 33 of the second separate module 30b and the gas inlet opening 32 of the first separate module 30a.

[0074] Figure 5 A cross-sectional view of an annular seal with a tapered end is shown, Figure 6 A cross-sectional view of an O-ring seal with a parallelogram cross-section is shown.

[0075] As Figure 4 shown, when the two separate modules 30 are stacked one on top of the other, to improve the sealing of the stack of the separate modules 30, more particularly to prevent leakage from the annular space between the injection tube 33 and the porous annular substrate 21 to the outside of the stack 20, for each stack 20, the lower separate module (here the second separate module 30b) includes a deformable annular seal 36 disposed between the lid 25 of the stack 20 and the support plate 31 of the upper separate module (here the first separate module 30a).

[0076] In addition, as Figure 3 and Figure 4As shown, the stack 20 also includes three legs (only one of which is visible for each stack in these Figure 3 and Figure 4 . Each leg 26 extends from the annular cover 25 towards the support plate 31 on which the stack 20 is arranged along the stacking direction Z of the porous annular substrate 21.

[0077] As Figure 7 shown, which represents an example of a variant embodiment of an injection tube according to the present invention, each injection tube 33 may include a main tube portion 33c that forms a shoulder 37 having a frustoconical-shaped second end 33b. The shoulder 37 allows the annular seal 35 to deform in a plane perpendicular to the first direction D z in which the porous annular substrate 21 is stacked along the first direction D z .

[0078] The chemical vapor infiltration densification method according to the present invention then includes the following steps: during which step, a gas phase of a gaseous precursor containing a matrix material to be deposited in the pores of the substrate 21 is injected into the internal volume 24 of each stack 20 of the porous annular substrate 21. The gas injection direction is indicated by the arrow G in Figure 4 .

[0079] In Figure 8 the shown embodiment, each individual module 30 covered by another separate module 30 also includes a plurality of rods 70 extending between the support plate 31 of the separate module 30 and the support plate 31 of the separate module 30 covering it to support the mass of the one or more separate modules 30.

[0080] The height of each rod 70 is less than the height of the stack 20 of the porous annular substrate 21. More specifically, the height of each rod 70 is less than the sum of the thicknesses of the deformable annular seal 36, the cover ring 25, the seal ring 23, and the porous annular substrate 21 of the stack in each stack 20.

Claims

1. A method for densifying a porous annular substrate (21) having a central channel (21a) by pressure gradient chemical vapor infiltration, the method comprising at least the following steps: - providing a stack (20) of a plurality of porous annular substrates (21), each stack (20) comprising an internal volume (24) formed by the central channels (21a) of the stacked porous annular substrates (21), - providing a plurality of individual modules (30), each individual module (30) comprising a support plate (31) and a stack (20) of porous annular substrates (21) arranged on the support plate (31), and for each stack (20), the support plate (31) comprising a gas inlet opening (32) leading to the internal volume (24), - forming a stack of individual modules (30) in the chamber of a densification furnace, each gas inlet opening (32) of the support plate (31) of a first individual module (30a) mounted on a second individual module (30b) communicating with the internal volume (24) of one of the stacks (20) of the second individual module (30b) so that gas circulates between the individual modules (30), and - injecting a gas phase of a gaseous precursor containing a matrix material to be deposited in the pores of a porous annular substrate (21) into the internal volume (24) of each stack (20) of the porous annular substrate (21), characterized in that, For each second separate module (30b) covered by a first separate module (30a), each stack (20) includes at least one cover ring (25), a seal ring (23), and a deformable annular seal (36); the cover ring (25) is supported on top of the stack of porous annular substrates (21) by an annular spacer (22), the seal ring (23) is arranged around the annular spacer (22) in a plane perpendicular to the stacking direction (D z ) of the porous annular substrates (21), and the deformable annular seal (36) is provided between at least one cover ring (25) and a support plate (31) of the first separate module (30a).

2. The method according to claim 1, wherein Each deformable annular seal (36) is arranged to be able to undergo a deformation greater than or equal to the thickness of the cover ring (25) in the direction (D z ) along which the porous annular substrate (21) is stackable.

3. The method according to any one of claims 1 and 2, wherein, Each stack (20) includes at least three legs (26) extending in the stacking direction (D z ) of the porous annular substrate (21), extending from the cover ring (25) to the support plate (31), and the stack (20) is arranged on the support plate (31).

4. The method according to claim 1, wherein for each stack (20), the support plate (31) of each individual module (30) comprising an injection tube (33) mounted on the gas inlet opening (32), the injection tube extending into the internal volume (24) of the stack (20) between a first tube end (33a) connected to the support plate (31) and a free second tube end (33b); the injection tube (33) further comprising a gas injection opening (34) leading to the internal volume (24), each gas inlet opening (32) of the support plate (31) of a first individual module (30a) mounted on a second individual module (30b) communicating with the second tube end (33b) of one of the injection tubes (33) of the second individual module (30b) to allow gas to circulate between the individual modules (30).

5. The method according to claim 4, wherein Each support plate (31) comprises a first surface (31a) on which the stack (20) is arranged and a second surface (31b) opposite the first surface (31a), each gas inlet opening (32) comprising a frustoconical shape having a first diameter (d1) and a second diameter (d2), the first diameter (d1) being formed in the second surface (31b) of the support plate (31), the second diameter (d2) being smaller than the first diameter (d1) and being formed in the first surface (31a) of the support plate (31) or formed between the first surface (31a) and the second surface (31b) of the support plate (31), and the second tube end (33b) of each injection tube (33) comprising a complementary frustoconical shape mating with the frustoconical shape of the gas inlet opening (32).

6. The method according to claim 4 or 5 further comprises the step of sealingly aligning the individual stacked modules (30), wherein the second tube end (33b) of each injection tube (33) of the second individual module (30b) is inserted into the gas inlet opening (32) of the first individual module (30a), and for each injection tube (33), the second individual module (30b) further comprises an annular seal (35) which is arranged between the second tube end (33b) of the injection tube (33) of the second individual module (30b) and the gas inlet opening (32) of the first individual module (30a) with which it cooperates.

7. The method according to claim 6, wherein Each injection tube (33) includes a main tube portion (33c) forming a shoulder (37), the shoulder (37) having a second tube end (33b) with a frustoconical shape, the shoulder (37) allowing the annular seal (35) to deform in a plane perpendicular to the direction (D z ) in which the porous annular substrate (21) is stacked.

8. According to the method described in claim 6 or 7, wherein, The annular seal (35) has a frustoconical shape.

9. The method according to any one of claims 1 to 2, wherein, For each injection tube (33), each support plate (31) comprises a centering ring which is centered on the gas inlet opening (32) and shaped to receive the injection tube (33).

10. The method according to any one of claims 1 to 2, wherein, Each porous annular substrate (21) contains carbon.

11. The method according to any one of claims 1 to 2, wherein, Each porous annular substrate (21) constitutes a fiber brake disc preform.

12. The method according to any one of claims 1 to 2, wherein, Each individual module (30) covered by another individual module (30) comprises a plurality of rods (70) extending between the support plate (31) of the individual module (30) and the support plate (31) of the individual module (30) covering it, and the rods support the weight of the at least one upper individual module (30).

13. The method according to claim 12, wherein, The height of each rod (70) is less than the height of the stack (20) of the porous annular substrates (21).

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