Preform for directional flow CVI densification

Abstract

The invention relates to an annular fibrous preform (200) extending between an inner edge (220) and an outer edge (230), characterized in that the annular fibrous preform comprises at least one through-groove (212) on at least one surface (210, 240).

Description

TECHNICAL FIELD

[0001] The present invention relates to the field of manufacturing preforms of composite materials, and more particularly to preforms densified by a directional flow chemical vapor infiltration process. BACKGROUND

[0002] Thermal structural composites are characterized by their high mechanical properties and the ability to maintain these properties at high temperatures. Typical examples of such thermal structural composites are carbon composites / carbon comprising a porous matrix densified with a carbon matrix and ceramic matrix composites comprising a porous matrix densified with a ceramic matrix.

[0003] Densification processes using chemical vapor infiltration are well known. One or more porous matrices are placed inside a chamber. A gas phase comprising one or more precursors of the matrix material is introduced into the chamber. Temperature conditions and pressure conditions are adjusted to allow the diffusion of the gas phase in the porosities of the matrices in order to deposit matrix-forming material by decomposition of the gas phase components or by reaction between the components.

[0004] Densification processes for porous matrices require reaching high temperatures, and in order to increase the productivity of the process, it is generally considered to densify a plurality of porous matrices in the same densification chamber. In the case of annular porous matrices, it is generally considered to introduce these porous matrices in the densification chamber in a stacked manner, all the central channels of the matrices being vertically aligned and each matrix being separated from the adjacent matrices by spacers.

[0005] In a well-known manner, these spacers can be made of Inconel or composite material, and these spacers ensure the circulation of the reactive gas phase in the matrices under the required pressure conditions and ensure that the matrices do not come into contact with each other.

[0006] However, the spacers placed between each preform represent a significant loss of space in the densification furnace.

[0007] Although the manufacturing method of composite parts is expensive and complex, the highly beneficial thermo-mechanical properties of composite parts are sufficient to make them competitive, but there is still a search for improvements in the manufacturing method of such parts. SUMMARY

[0008] The present invention is particularly intended to improve the existing directional flow chemical vapor infiltration process, and to provide a new preform avoiding the use of spacers, thus saving space in the densification furnace.

[0009] According to a first aspect of the invention, the invention relates to an annular fibrous preform extending between an inner edge and an outer edge, characterized in that the annular fibrous preform comprises at least one through groove on at least one surface.

[0010] For the purposes of the present invention, a through groove is defined as a groove cut into the surface of a preform and extending from the inner edge to the outer edge of the preform.

[0011] Thanks to the presence of at least one through groove, when an annular preform according to the present invention is stacked with another annular preform, whether or not according to the present invention, the inner space and the outer space of the stack remain in fluid communication.

[0012] The presence of the grooves makes it possible to use the preforms in a stacked manner in a conventional furnace for a directional flow chemical vapor infiltration process, without the need for spacers.

[0013] More particularly, in a directional flow chemical vapor infiltration process, an opening is usually made in the spacers between the inner space and the outer space of the stack of preforms.

[0014] This opening can ensure a controlled pressure difference between the outer space and the inner space of the fibrous preform.

[0015] The inventors have the merit of having thought of obtaining a part having the same thermo-mechanical properties and shape as the parts obtained by the prior art methods, even if the grooves are present directly on the fibrous preform, while not requiring spacers.

[0016] Furthermore, conventionally, the outer surfaces of the preforms are machined after the chemical vapor infiltration process, since these surfaces have been in contact with the gas phase and do not have the same properties as the core of the preform.

[0017] Furthermore, the dimensions of the densified parts must be precisely adapted to their final application, for example, in the case where these densified parts are used as friction members, for example, brake discs, their arrangement in the heat sink.

[0018] Thus, and in particular in the embodiment where the dimensions of the grooves are less than the thickness of the material removed by the final machining, the preforms of the present invention make it possible to obtain composite parts identical in all respects to the parts obtained by the prior art methods, but using a simplified method.

[0019] In one embodiment, the one or more through grooves are straight grooves, i.e. the width of the groove is constant along the entire length of the groove (from the inner edge to the outer edge). The recess created by the through groove on the surface of the fibrous preform can for example be rectangular in shape.

[0020] In one embodiment, the preform comprises a plurality of through grooves on at least one of its surfaces.

[0021] For example, the preform can comprise a plurality of through grooves distributed angularly over the entire surface of the fibrous preform.

[0022] For all the grooves present on the surface of the fibrous preform, the through grooves are said to be "angularly distributed" if the angle formed by the directions of two adjacent grooves is the same.

[0023] In one embodiment, at least one through groove is present on each surface of the fibrous preform.

[0024] In the case where grooves are present on several surfaces, these grooves can be identical or different.

[0025] In one embodiment, the one or more through grooves have a variable width between the inner edge and the outer edge. This embodiment makes it possible to adjust the geometry of the opening more precisely in order to achieve the desired densification gas phase flow through the through groove.

[0026] For example, the edges of the one or more grooves can be aligned with the radial direction of the preform.

[0027] In one embodiment, the thickness of the preform varies depending on whether it is measured at a point where a through groove is present on the surface of the preform or at a point where no groove is present. Thus, a minimum thickness of the preform and a maximum thickness of the preform can be defined.

[0028] In one embodiment, the minimum thickness of the preform is greater than or equal to 75% of the maximum thickness of the preform.

[0029] Such an embodiment can ensure that the grooves play the role usually assigned to spacers, while guaranteeing that they can reduce the size of the stack of preforms compared to the prior art where the preforms are superimposed with spacers.

[0030] In one embodiment, the thickness of the preform can be greater than or equal to 15 mm, or even 20 mm, even at the point where the thickness of the preform is the smallest.

[0031] This ensures that once the final machining has been carried out, the part obtained has sufficient dimensions for applications such as use as a friction part, for example as a brake disc.

[0032] In such an embodiment, the portion without through groove can extend over at least 75% of the thickness of the preform.

[0033] In one embodiment, the width of the one or more through grooves is less than or equal to 20 mm.

[0034] In the case where the one or more through grooves have a variable width, the width of the groove can be greater than or equal to 10 mm and less than or equal to 20 mm.

[0035] In one embodiment, the width of the recess can increase from the inner edge of the preform to the outer edge of the preform.

[0036] In this embodiment, the amount of material to be removed after densification is reduced, making machining easier.

[0037] In one embodiment, the width of the recess can decrease from the inner edge of the preform to the outer edge of the fibrous preform.

[0038] In one embodiment, the depth of the one or more through-recesses is less than or equal to 2.5 mm.

[0039] This depth ensures that the depth of the recess is less than the thickness of the preform removed during final machining.

[0040] In one embodiment, the thickness of the fibrous preform removed is less than or equal to 5 mm, for example between 2.8 mm and 3.2 mm, or even equal to 3 mm.

[0041] In one embodiment, the surface of the fibrous preform comprising the through-recess can further comprise a circular groove on the surface of the fibrous preform, the circular groove being in contact with the inner edge.

[0042] When such a groove is present, the through-recess is thus located between the circular groove and the outer edge of the fibrous preform. In other words, the through-recess opens onto the groove.

[0043] This embodiment avoids the deposition of pyrolytic carbon on the inner diameter of the preform, which would form bubbles at the end of the process, as observed in preforms without such a groove.

[0044] In one embodiment, the surface of the preform comprising the through-recess can further comprise a circular groove on the surface of the preform comprising the through-recess, the circular groove being in contact with the outer edge.

[0045] When such a groove is present, the through-recess is thus located between the circular groove and the inner edge of the preform.

[0046] This method makes it easier to disassemble the stack of preforms after carrying out the densification process.

[0047] If present, the depth of the one or more circular grooves in contact with the inner edge and / or the outer edge can be less than or equal to 2.5 mm and the width can be less than or equal to 5 mm.

[0048] As with the through-recess, the groove can be present only on one surface of the preform or on both surfaces of the preform.

[0049] The inventors have also found that these dimensions allow a good circulation of the gas phase during the directed flow chemical vapor infiltration process.

[0050] The annular fibrous preform can preferably be a preform comprising silicon carbide, SiC, fibers or carbon fibers.

[0051] In one embodiment, the fibrous preform is a friction component preform, for example, an aircraft brake disc preform.

[0052] In one embodiment, the fibrous preform is a preform for a friction component, for example, an aircraft brake disc, and the one or more surfaces comprising grooves are used to form one or more outer surfaces of the friction component.

[0053] In other words, at least initially, the preform comprises surfaces comprising grooves which are used to form outer surfaces of the friction component.

[0054] In one embodiment, the annular fibrous preform has an inner diameter between 15 cm and 25 cm, an outer diameter between 40 cm and 50 cm, and a thickness between 20 mm and 30 mm.

[0055] According to another aspect of the application, the application relates to a method of manufacturing an annular fibrous preform extending between an inner edge and an outer edge, the preform comprising at least one through groove on at least one surface, the method comprising at least the following steps:

[0056] (a) a step of hardening the annular fibrous preform; then

[0057] (b) a step of engraving at least one through groove on at least one surface of the hardened preform.

[0058] The inventors have surprisingly found that if the first step (a) of hardening the preform is performed, it is possible to simply engrave grooves on the preform.

[0059] More particularly, if the engraving of the preform takes place before it is densified and the preform therefore has poor mechanical strength, it is not possible to engrave grooves on the surface of the preform without taking special precautions due to the lower mechanical strength of the preform.

[0060] However, once hardened, the preform can be engraved precisely and the fibrous nature of the preform is not sufficient for it to return to its original shape.

[0061] In one embodiment, the step (a) of hardening the preform can be performed by impregnation with a hardening compound, for example, polyvinyl alcohol, commonly referred to as PVA, polyethylene glycol, commonly referred to as PEG, or a mixture of these compounds.

[0062] For example, the hardening step (a) can be performed by immersing the preform in a bath comprising the hardening compound, then optionally passing it through an oven.

[0063] Alternatively, the hardening step (a) can be performed by impregnating (for example, by means of a spray) the one or more surfaces of the preform to be engraved with the hardening compound.

[0064] This embodiment allows the use of a smaller amount of hardening compound, which reduces the overall cost of the method.

[0065] In both cases, the use of a hardening agent makes the preparation of the preform relatively simple.

[0066] In particular, there is no need to treat the hardened engraved preform to remove the hardening agent, since the temperature required for the subsequent densification step of the preform will be sufficient to remove the hardening compound by pyrolysis, whether it has impregnated the entire or only a part of the preform.

[0067] In one embodiment, the step (a) for hardening the preform can be broken down into two sub-steps (al) and (a2).

[0068] In one embodiment, the step (a) can comprise at least the following steps:

[0069] (al) a step of saturating the annular fibrous preform with water; then

[0070] (a2) a step of hardening the preform by reducing the temperature to below 0°C, preferably to less than or equal to -5°C (for example, equal to -5°C).

[0071] Reducing the temperature of the preform saturated with water during step (al) during step (a2) allows the water introduced to freeze and thus harden the preform.

[0072] This method is particularly preferred because it avoids the use of chemical compounds, making the method more environmentally friendly.

[0073] Furthermore, after the step (b) of engraving the fibrous preform, the preforms saturated with water will need to be simply baked in order to dry them before introducing the preforms into the densification furnace.

[0074] In one embodiment, and regardless of the implementation of the step (a), the step (b) can be performed by means of cutting the object or by milling (for example, grinding).

[0075] Steps (a) and (b) together make it possible to obtain the preform with at least one through groove described above.

[0076] According to another aspect of the application, the application also relates to a stack of a plurality of fiber preforms, each fiber preform being as described above.

[0077] Unlike prior art methods, the advantage of this type of stack is that it can be introduced into the densification chamber without the need to place spacers between the fiber preforms.

[0078] In this way, more preforms can be introduced into the densification chamber without degrading the quality or thickness of the part obtained after densification.

[0079] According to another aspect of the application, the application relates to a method for manufacturing a composite material part, the method comprising at least the following steps:

[0080] (c) densifying the stack of annular fiber preforms by a directional flow chemical vapor infiltration process, at least one annular fiber preform being as described above; then

[0081] (d) separating the densified preform obtained from the directional flow chemical vapor infiltration process; then

[0082] (e) a final machining step of the surface of the densified fiber preform.

[0083] Unlike prior art directional flow chemical vapor infiltration processes, the method according to the application does not require the use of spacers.

[0084] Thus, in one embodiment, the stack of annular fiber preforms comprises annular fiber preforms in direct contact with each other.

[0085] In one embodiment, the stack of annular fiber preforms can be the stack of preforms just described.

[0086] Given the usual dimensions of the stack of preforms, the usual dimensions of the densification furnace used for the chemical vapor infiltration process and the usual dimensions of the densification spacers, the absence of spacers can result in an increase in the number of preforms impregnated during one complete densification cycle of at least 7.5%, or even between 7.5% and 15%. The absence of spacers means that the method of the application saves a significant amount of space in the furnace.

[0087] The one or more grooves present on the surface of the fiber preform perform the function usually assigned to the spacers.

[0088] In one embodiment, all the preforms of the stack meet the above-mentioned condition. However, this feature is not essential and it can be advantageous to include some conventional annular fibrous preforms (i.e. without through grooves) in order to optimize the pressure difference between the inside and the outside of the preforms, which is a function of the size and number of grooves present in the final stack.

[0089] However, densification by chemical vapor infiltration process leads to the adhesion of the preforms of a given stack together, in the absence of spacers.

[0090] The inventors' contribution lies in the fact that they have found that, even including the separation of the preforms obtained, it is still achieved to obtain a composite part by using a method that is overall more efficient than the methods of the prior art.

[0091] In one embodiment, spacers, for example made of ceramic material, can be present at the top and at the bottom of the stack of preforms.

[0092] Such spacers make it possible, for example, to avoid the adhesion of the preforms at the ends of the stack to the elements of the furnace, such as the trays on which the preforms are placed.

[0093] Step (d) for separating the preforms can be carried out in various ways.

[0094] In one embodiment, separation step (d) can be carried out by mechanical separation.

[0095] For example, separation step (d) can be carried out by a mechanical cutting operation, for example by means of a saw, for example a circular saw of sufficient diameter or a saw with reciprocating blade movement.

[0096] More particularly, the mechanical cutting step makes it possible to easily separate the preforms and without damaging them over a thickness greater than the thickness that will be removed during the final machining step (e).

[0097] In one embodiment, steps (d) and (e) can be carried out using a single cutting step but with a saw whose blade thickness corresponds to the thickness to be removed between two preforms.

[0098] Alternatively, the inventors have found that step (d) for separating the fibrous preforms can be implemented as a heat treatment step carried out at a temperature greater than or equal to 1600°C, preferably greater than or equal to 2000°C.

[0099] Such step (d) for separating the preforms is particularly preferred because the high-temperature heat treatment is recommended for completing the production of the composite part.

[0100] The high-temperature heat treatment causes the matrix formed on the surface of the fibrous preform to shrink, leading to the separation of two consecutive preforms in the stack, which have become attached to each other during the chemical vapor infiltration process due to the deposition of the reactive gas phase on their respective surfaces. If the preforms do not separate completely, their adhesion is sufficiently reduced to enable separation by the application of a moderate mechanical force.

[0101] In one embodiment, the separation step (d) can be a mechanical separation step, followed by a heat treatment at a temperature greater than or equal to 1600°C, preferably greater than or equal to 2000°C.

[0102] Finally, the method of manufacturing a composite part comprises a step (e) of machining the surface of the preform.

[0103] In particular, the presence of through grooves in the final part is not desirable, it is therefore necessary to remove said grooves from the final part.

[0104] However, it should be noted that this step does not introduce any additional complexity compared to the prior art methods for manufacturing composite parts.

[0105] Conventionally, after obtaining a composite part using a chemical vapor infiltration process, the surface thereof is machined because the surface of the fibrous preform is more exposed to the reactive gas phase during the chemical vapor infiltration process and therefore does not have the same properties as the rest of the part.

[0106] For example, step (e) enables the surface of the fibrous preform to be machined to a thickness greater than 3.0 mm, for example between 3.0 mm and 5.0 mm.

[0107] This machining step (e) removes the surface of the preform that was in contact with the reactive gas phase of the chemical vapor infiltration process and thus ensures the homogeneity of the properties of the composite part obtained at the end of the method by removing the part that was most exposed to the reactive gas phase. Furthermore, this step (e) enables the part to have the desired dimensional tolerances, enabling these parts to be mounted in a heat sink.

[0108] In one embodiment of the method of the application, the composite part comprises carbon fibers and a carbon matrix.

[0109] In one embodiment of the method of the application, the composite part is a friction part, for example an aircraft brake disc.

[0110] The above features and advantages and other features and advantages will become apparent to those of ordinary skill in the art by reading the following detailed description, with reference to the drawings in which: BRIEF DESCRIPTION OF DRAWINGS

[0111] [ Figure 1 ] Figure 1 An apparatus for performing a directed flow chemical vapor infiltration method is schematically illustrated.

[0112] [ Figure 2 ] Figure 2 A fiber preform of the present invention in one embodiment of the invention is schematically illustrated.

[0113] [ Figure 3 ] Figure 3 A fiber preform of the present invention in one embodiment of the invention is schematically illustrated.

[0114] [ Figure 4 ] Figure 4 A stack of fiber preforms for performing a method of the present invention is schematically illustrated.

[0115] [ Figure 5 ] Figure 5 A fiber preform of the present invention in one embodiment of the invention is schematically illustrated.

[0116] [ Figure 6 ] Figure 6 is a flow chart showing steps in a method for manufacturing a composite part according to the present invention. DETAILED DESCRIPTION

[0117] The present invention will now be described by means of the enclosed drawings having a descriptive purpose showing certain embodiments of the invention, but should not be construed as limiting the invention.

[0118] With regard to Figure 1 An example of an apparatus 100 for chemical vapor infiltration of a porous preform is described.

[0119] Figure 1 A schematic view of a gas phase chemical vapor infiltration densification apparatus 100 is shown, the loading zone 140 of which is defined by a cylindrical side wall 101, a bottom wall 102 and a top wall 103.

[0120] The substrate 130 to be densified, in this case an annular fiber preform, can be arranged in the loading zone 140 in the form of a plurality of annular vertical stacks 131 placed on a loading tray 120. This comprises a plurality of passages 121 aligned with the inner volume 130a of the stacks, and each stack is closed at the top by a lid 132.

[0121] Preferably, the stacks 131 of matrices 130 are placed on a loading tray 120 and can be divided into a plurality of superimposed sections separated by one or more intermediate trays 122 having a central passage 122a aligned with the central passage of the matrices 130. Figure 1 The stacks 131 are shown in which the fibrous preforms 130 are in direct contact with each other. More specifically, each stack of matrices 131 comprises at least one preform as described and comprises through grooves which ensure fluid communication between the internal volume 130a and the external volume 141 and make it possible to dispense with the spacers normally used.

[0122] The dimensions of the through grooves of the preforms 130 of the present application can be chosen so as to substantially balance the pressure between the volume 130a and the volume 141.

[0123] A gas flow (indicated by the arrows) comprising one or more gaseous precursors of the material constituting the matrix enters the furnace through the inlet aperture 104 defined by the duct 106.

[0124] The gas phase is then conveyed from the loading tray 120 into the internal volumes 130a of the stacks 131 by means of the passages 121. The gas phase then enters the volumes 141 external to the stacks inside the loading zone 140. The effluent gas is extracted through the passages 105 formed in the top wall 103, which are connected by means of the ducts 107 to suction means, such as a vacuum pump (not shown).

[0125] In one embodiment, the gas phase can pass through a preheating zone, for example located between the inlet aperture 104 and the loading tray 120.

[0126] In the embodiment shown, the gas phase simply enters the distribution zone 170, which makes it possible to distribute the phase well between the various internal volumes 130a of the stacks 131 of preforms 130.

[0127] In the example described here, the heating means 110 of the apparatus are inductive heating elements. More specifically, the cylindrical side wall 101 which defines the loading zone 140 constitutes an armature or susceptor, for example made of graphite, which is coupled with an inductor 108 located outside the furnace and formed by at least one induction coil. An insulator 109 is interposed between the inductor 108 and the wall 101. In a known manner, when the inductor 108 is supplied with an AC voltage, the furnace is heated by heating the armature 101. To this end, the induction coil or coils are connected to an AC voltage generator (not shown).

[0128] The magnetic field generated by the inductor 108 induces an electric current in the wall 101 (susceptor), which, by Joule effect, heats the wall 101, the elements present inside the wall 101 being heated by radiation.

[0129] The heating device 110 of the device 100 can be provided by other means such as an electric heating device consisting of, for example, a heating resistor embedded in the wall 101.

[0130] Figure 2 An annular fiber preform in a first embodiment of the application is shown.

[0131] The annular fiber preform 200 comprises an inner edge 220 and an outer edge 230.

[0132] Preferably, as shown here, the preform 200 has a circular shape.

[0133] The preform also comprises two flat surfaces 210 and 240, respectively called upper surface 210 and lower surface 240. However, it should be understood that this terminology is by no means exhaustive.

[0134] In Figure 2 In the embodiment shown, the preform 200 comprises a through recess 212 on its upper surface 210.

[0135] In this case, the through recess 212 is a straight slot, but this is not limiting to the application.

[0136] Figure 3 An alternative embodiment of a preform 200 according to the application is shown.

[0137] In Figure 3 In the alternative embodiment shown, the preform comprises a recess 212 on both its upper surface 210 and its lower surface 240.

[0138] In this embodiment, the through recesses 212 on both sides are identical, but this is not mandatory.

[0139] As Figure 2 and Figure 3 shown, the term used should not be understood to mean that the through recess 212 passes through the preform from the upper surface 210 to the lower surface 240. In particular, as shown, the one or more through recesses pass through the preform 200 from the inner edge 220 to the outer edge 230.

[0140] In the alternative embodiment shown in Figure 4 In this alternative embodiment, the preform can also be arranged so that the through recesses do not face each other.

[0141] The two fiber preforms correspond to Figure 2 The preform 200 shown, whose through recesses are arranged opposite each other. In other words, the two upper surfaces 210 of the preforms are arranged in contact with each other.

[0142] In the embodiment shown, the single channel is formed by joining the through-going recesses 212 of the two preforms, such that fluid communication between the interior of the preforms and the exterior of the preform 200 is achieved.

[0143] In the case of Figure 4 In an alternative design shown, two preforms 200 can also be provided as shown, but such that the through-going recesses of one side do not face the through-going recesses of the other side.

[0144] Figure 5 A preform in one embodiment of the application is shown.

[0145] The preform 200 comprises a circular groove 250 at an inner edge 220 on the upper surface 210 of the preform. The through-going recess 212 then extends between the circular groove 250 and an outer edge 230.

[0146] The circular groove 250 is created on the surface of the preform 200 at the same time and in the same manner as the through-going recess 212.

[0147] Figure 6 A flow chart showing various stages in a method for manufacturing a composite material part is shown.

[0148] The method comprises a plurality of steps which have been numbered above as (a) to (e).

[0149] Step (a) is a step of hardening the fibrous preform.

[0150] This ensures that the preform has sufficient mechanical strength in order to be engraved.

[0151] Step (b) is a step of engraving the hardened preform.

[0152] This can advantageously be performed by cutting with a cutting object or by milling, for example by grinding. More specifically, the hardening of the fibrous preform enables the preform to be cut precisely, which is not possible on a fibrous preform which is not hardened, as the fibrous preform which is not hardened does not have sufficient mechanical strength.

[0153] Step (c) is a step of densifying the stack of preforms using a directional flow chemical vapour infiltration process.

[0154] This process has been described above in relation to Figure 1 The process has been described above.

[0155] For example, the process can use a reactive gas phase comprising, for example, methane, ethane, propane, butane or a mixture of these gases, the reactive gas phase optionally comprising a neutral carrier gas, for example argon.

[0156] In particular, such a reactive gas phase makes it possible to obtain a matrix of pyrocarbon in the annular fibrous preform, but it will be understood that the person skilled in the art knows how to select other reactive gas phases to obtain other matrix phases.

[0157] For example, the chemical vapor infiltration process can be carried out in a chamber at a temperature of 950°C to 1050°C for 100 to 800 hours.

[0158] The method can also comprise a step (d) of separating the densified preform obtained at the end of the chemical vapor infiltration process.

[0159] As mentioned above, this step can be carried out by mechanical cutting or high-temperature heat treatment.

[0160] Such a step (d) can be carried out by heat treatment at a temperature greater than or equal to 2000°C for more than 60 minutes.

[0161] Preferably, this heat treatment can even be carried out after step (d) by mechanical cutting.

[0162] Finally, step (e) involves machining the surface of the densified part. Machining is generally carried out in order to correct the upper and lower surfaces of the densified part.

[0163] For example, this step (e) can be carried out by grinding the surface of the preform 200.

[0164] Machining (e) can be intended to remove a thickness of 2.0 mm to 5.0 mm of the surface of the preform.

[0165] The composite part obtained by the method just described can be a carbon / carbon composite part, for example a friction part or even a brake disc.

Claims

1. An annular fiber preform (200) extending between an inner edge (220) and an outer edge (230), characterized in that, The preform comprises at least one through groove (212) on at least one surface (210, 240).

2. The preform (200) according to claim 1, wherein, The at least one through groove (212) has a constant width from the inner edge (220) to the outer edge (230).

3. The preform (200) according to claim 1 or 2, wherein The annular fibrous preform comprises a plurality of through grooves (212) angularly distributed over the entire surface of the preform.

4. The preform (200) according to any one of claims 1 to 3, wherein, There is at least one through groove (212) on each of the surfaces (210, 240) of the fibrous preform.

5. The preform (200) according to any one of claims 1 to 4, wherein, The preform is a brake disc preform.

6. The preform (200) of claim 5, wherein, The one or more surfaces comprising grooves are used to form one or more outer surfaces of the friction component.

7. The preform (200) according to any one of claims 1 to 6, wherein, The minimum thickness of the preform is greater than or equal to 75% of the maximum thickness of the preform.

8. A stack of two or more preforms (200) according to any one of claims 1 to 7, characterized in that The preforms are in direct contact with each other.

9. A manufacturing method of an annular fibrous preform (200) extending between an inner edge (220) and an outer edge (230), the preform comprising at least one through groove (212) on at least one surface (210, 240), the method comprising at least the following steps: (a) a step of hardening the annular fibrous preform; then (b) a step of engraving at least one through groove on at least one surface of the hardened preform.

10. The manufacturing method according to claim 9, wherein, The hardening step (a) comprises at least the following steps: (a1) a step of saturating the annular fibrous preform (200) with water; then (a2) a step of hardening the preform by reducing the temperature to below 0°C.

11. A method for manufacturing a composite material component comprising at least the following steps: (c) densifying a stack (131) of annular fibrous preforms (200, 130) by a directional flow chemical vapor infiltration process, at least one of the annular fibrous preforms being an annular fibrous preform according to claims 1 to 8; then (d) separating the densified preforms obtained at the end of the directional flow chemical vapor infiltration process; then (e) a step of final machining of the surfaces of the densified fibrous preforms.

12. The method for manufacturing a composite material part according to claim 11, wherein, The stack (131) of annular fibrous preforms comprises annular fibrous preforms in direct contact with each other.

13. The method of claim 11 or 12, wherein, Step (d) is a heat treatment step carried out at a temperature greater than or equal to 1600°C.

14. The method of any one of claims 11 to 13, wherein, The composite material component comprises carbon fibers and a carbon matrix. The preform is a brake disc preform. The one or more surfaces comprising grooves are used to form one or more outer surfaces of the friction component. The minimum thickness of the preform is greater than or equal to 75% of the maximum thickness of the preform. The preforms are in direct contact with each other.

9. A manufacturing method of an annular fibrous preform (200) extending between an inner edge (220) and an outer edge (230), the preform comprising at least one through groove (212) on at least one surface (210, 240), the method comprising at least the following steps: (a) a step of hardening the annular fibrous preform; then (b) a step of engraving at least one through groove on at least one surface of the hardened preform. The hardening step (a) comprises at least the following steps: (a1) a step of saturating the annular fibrous preform (200) with water; then (a2) a step of hardening the preform by reducing the temperature to below 0°C.

11. A method for manufacturing a composite material component comprising at least the following steps: (c) densifying a stack (131) of annular fibrous preforms (200, 130) by a directional flow chemical vapor infiltration process, at least one of the annular fibrous preforms being an annular fibrous preform according to claims 1 to 8; then (d) separating the densified preforms obtained at the end of the directional flow chemical vapor infiltration process; then (e) a step of final machining of the surfaces of the densified fibrous preforms. The stack (131) of annular fibrous preforms comprises annular fibrous preforms in direct contact with each other. Step (d) is a heat treatment step carried out at a temperature greater than or equal to 1600°C. The composite material component comprises carbon fibers and a carbon matrix.

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