Localized heat treatment process for an aircraft brake disc

Abstract

A localized heat treatment process for an aircraft brake disc (1) made of a carbon / carbon composite material, the disc (1) having two friction surfaces, each located on one side of the disc (1), the process being characterized in that it comprises: - electrical contact of an electrode (11), on each side of the disc (1), with a treatment area (17) of the disc (1), an electrical insulator (14) being disposed on at least one friction surface, in the vicinity of the treatment area (17), and - the generation of an electric current between the two electrodes (11), so as to heat said treatment area (17) by Joule heating. Figure 11

Description

Title of the invention: Method for localized heat treatment of an aircraft brake disc

[0001] The invention relates to parts comprising a composite material having a carbon fiber-reinforced matrix, and in particular a carbon / carbon composite material (with a carbon matrix), a C / C-SiC composite material (with a C-SiC matrix), a C / SiC composite material (with a SiC matrix), or a C / ceramic composite material (with a ceramic matrix), especially friction parts such as aircraft brake discs. More particularly, the invention relates to a method for localized heat treatment of an aircraft brake disc, as well as a device for implementing the method.

[0002] Ceramic matrix composites, or CMCs, are composite materials characterized by a set of ceramic fibers embedded in a ceramic matrix. Both the fibers and the matrix can be made of any known ceramic, including carbon.

[0003] Carbon / carbon composite, or C / C, is a composite material comprising an addition of carbon fibers in a carbon matrix, typically graphitizable carbon.

[0004] Currently, the final properties of ceramic matrix composites, of the C / C type, are intrinsically linked to their manufacturing processes. The final properties of the composite represent a compromise between the complexity of the manufacturing process and the precision of the material properties. Industrial processes for manufacturing these C / C materials only allow for work on the scale of a single part or larger. Aircraft brake discs are, in fact, mass-produced, and their properties are averaged across the disc, with the exception of surface treatments such as an external anti-oxidation coating (AOC) or the machining stage. Given the manufacturing processes typically used, it is therefore not currently possible to locally adjust the material properties according to the stresses experienced locally by the part.

[0005] Three cases can illustrate this problem.

[0006] A first case concerns the deposition of an internal or external anti-oxidation coating (AOC) by painting and diffusion into the pores, followed by curing. Curing is carried out by heating the entire part, or, failing an industrial solution, by localized heating only in the areas coated with the internal or external AOC. Heating an entire disc requires more Energy and a suitable chemical environment (neutral gas) are required to prevent part degradation. A large-volume, sealed oven is used.

[0007] A second case concerns the lugs / notches of aircraft brake discs. These are preferential areas of damage because they are subjected to significant mechanical stresses. It is not currently possible to specifically reinforce these areas without modifying the entire disc, which can result in reduced braking performance, increased wear, or a significant increase in manufacturing cost.

[0008] A final case concerns the impregnation of an aircraft brake disc to load the part with ceramics. This added filler reduces cold friction wear but slightly increases oxidation at high temperatures. The studs and non-friction areas (areas not intended to rub against a corresponding friction area of ​​an adjacent disc) are also loaded with ceramics because it is not possible to load only the friction faces of the disc. Under these conditions, the behavior of the non-friction areas is therefore degraded (sensitivity to oxidation) in favor of the cold wear resistance of the friction areas.

[0009] The invention aims to remedy these drawbacks by proposing a localized high-temperature process, allowing adjustment of the properties of the different functional zones of the disk.

[0010] The invention thus relates to the localized heat treatment of an aircraft brake disc comprising a composite material having a matrix reinforced by carbon fibers, the disc being provided with two friction faces each located on one side of the disc.

[0011] The method according to the invention comprises: - electrical contact of an electrode, on each side of the disc, with an area to be treated on the disc, an electrical insulator being placed on at least one friction face, preferably on each friction face, in the vicinity of the area to be treated, and - the generation of an electric current between the two electrodes, so as to heat the said area to be treated by Joule effect.

[0012] Thus, the passage of an electric current through the area to be treated, combined with the presence of electrical insulation around the area, allows for localized heat treatment, limited to the area to be treated. Only the area to be treated is heated, and not the entire disc, which reduces the treatment time and associated costs. The heating kinetics can be controlled, with rapid heating, particularly rapid "flash" heating, such as that obtained during flash sintering, to limit heat diffusion.

[0013] The electrical insulator is arranged in a vicinity of the area to be treated, advantageously so as to insulate the other parts of the disk outside the area to be treated.

[0014] The composite material comprising a matrix reinforced by carbon fibers can be a carbon / carbon (C / C) composite material, a C / C-SiC composite material, a C / SiC composite material, or a C / ceramic composite material.

[0015] Each friction face may include a friction zone, a fixing zone and a free zone, and the area to be treated may include a part of each friction zone, a part of each fixing zone, or a part of each free zone.

[0016] Each friction zone can extend radially between a mounting zone and a free zone. A free zone is an area adjacent to a friction zone that is neither a friction zone nor a mounting zone. A mounting zone is an area intended to be attached to a landing gear axle, in the case of a stator disc, or an area intended to be attached to a wheel rim of a landing gear, in the case of a rotor disc.

[0017] One or more treatment zones can be considered, extending through the entire thickness of the disc or not; for example, a treatment zone that includes two opposing friction surfaces. For this purpose, two electrical contact zones for the electrodes can be implemented, symmetrical with respect to the plane of symmetry of the disc; for example, two electrical contact zones belonging to the two friction zones, the two fixing zones, or the two free zones.

[0018] The disc can be a stator disc, each fixing area being a radially internal area intended to be fixed to an axle of a landing gear, and each free area being a radially external area.

[0019] The disc can be a rotor disc, each attachment zone being a radially external zone intended to be attached to a wheel rim of a landing gear, and each free zone being a radially internal zone.

[0020] The area to be treated may be coated with an anti-oxidation protection agent or an anti-oxidation protection precursor mixture before heating the area to be treated by Joule effect. In this case, the Joule effect heating may be carried out at a temperature between 500 and 1000°C, for a duration of between 2 seconds and one hour.

[0021] The area to be treated may include a portion of each fixing zone, and each fixing zone may be coated with resin before Joule heating of the area to be treated. In this case, Joule heating may be carried out at a temperature between 200 and 1000°C, for a duration of between 5 minutes and four hours.

[0022] The area to be treated may include a part of each fixing area, and ceramic fillers (such as borides, carbides, oxides, refractory metals (Ta, W)) or a ceramic precursor may be introduced into the area to be treated before heating the area to be treated by Joule effect.

[0023] The disc may include an inner zone located within the thickness of the disc, and the area to be treated may include a portion of the inner zone. In particular, the area to be treated may include a portion of the inner zone and a portion of each of the friction zones.

[0024] The invention also relates to a disc obtained by the process described above.

[0025] The invention finally relates to a device for implementing a method of localized treatment described above. The device includes a hermetically sealed enclosure under a neutral gas atmosphere, inside which is disposed an aircraft brake disc comprising a composite material having a matrix reinforced by carbon fibers, the disc being provided with two friction faces each located on one side of the disc, and the device may further include two electrodes connected to an electric current generator and suitable for being applied each on one side of the disc on an area to be treated of the disc, an electrical insulator being disposed on at least one friction face in a vicinity of the area to be treated.

[0026] Other features and advantages of the present invention will become apparent from the following detailed description of a non-limiting example of implementation, made with reference to the accompanying figures in which:

[0027] [Fig-1] is a schematic front view of an aircraft brake stator disc,

[0028] [Fig.2] is a cross-sectional view AA of the disk of [Fig.1],

[0029] [Fig.3] is a schematic front view of an aircraft brake rotor disc,

[0030] [Fig.4] is a cross-sectional view BB of the disk of [Fig.3],

[0031] [Fig.5] is a schematic exploded perspective view of a device enabling the implementation of a method according to the invention for the localized treatment of an aircraft brake disc,

[0032] [Fig.6] is a schematic half-view of the device applied to a stator disk,

[0033] [Fig.7] is a schematic view of the device applied to a rotor disk,

[0034] [Fig.8] is a schematic half-view of the device during a first step of a method according to the invention for localized treatment of an aircraft brake disc,

[0035] [Fig.9] is a schematic half-view of the device during a second step of a method according to the invention for localized treatment of an aircraft brake disc,

[0036] [Fig. 10] is a schematic half-view of the device during a third step of a method according to the invention for localized treatment of an aircraft brake disc,

[0037] [Fig. 11] is a schematic half-view of the device during a fourth step of a method according to the invention for localized treatment of an aircraft brake disc, and

[0038] [Fig. 12] is a schematic half-view of the device during a fifth step of a method according to the invention for localized treatment of an aircraft brake disc.

[0039] Aircraft brake discs are stacked one on top of the other, forming what is called a "heat sink" due to the temperature they can reach (up to 2,000 °C). Half of these discs are attached to a wheel (or rim) of the landing gear and rotate with it: these are the rotor discs. The other half are attached to the aircraft via the axle and do not rotate: these are the stator discs. The rotor discs and stator discs are mounted alternately. It is the friction of the discs against each other that provides the braking effect.

[0040] As illustrated in Figures 1 and 2, a stator disc 1 comprises two friction faces 2. The stator disc 1 is provided, on each of its two friction faces 2, with a friction zone 3, intended to rub against a corresponding friction zone 30 of a rotor disc 10 (as shown in Figures 3 and 4), a free radially external zone 4 (not subject to friction), and a radially internal mounting zone 5 surrounding a central annular opening 6. The radially internal mounting zone 5 comprises notches / grooves defining slots that are intended to fit onto load-bearing bars of the landing gear axle. The friction zone 3, the free radially external zone 4, and the radially internal mounting zone 5 are annular in shape.

[0041] Brake discs, whether stator discs 1 or rotor discs 10, are generally annular in shape, with a thickness in an axial direction and a diameter in a radial direction, with respect to an axis X around which the wheel rotates. An axle is configured to pass through the opening 6. Each brake disc 1 has two friction faces 2: one facing axially to an end plate and the other facing axially to a pressure plate. A line normal to each of the friction faces 2 is parallel to the axis X around which the wheel rotates, such that a plane in which each brake disc lies is orthogonal to the axis X around which the wheel rotates.

[0042] As can be seen in [Fig.2], the two friction zones 3 of the stator disk 1 (each friction zone 3 being associated with a friction face 2 of the stator disk 1) axially surround an inner zone 7 which is the core of the disk.

[0043] As illustrated in Figures 3 and 4, a rotor disk 10 also comprises two friction faces 20. The rotor disk 10 is provided, on each of its two friction faces 20, with a friction zone 30, intended to rub against a corresponding friction zone 3 of a stator disk 1 (as shown in Figures 1 and 2), a free radially internal zone 40 (not subject to friction) surrounding a central annular opening 60, and a radially external fixing zone 50. The friction zone 30, the free radially internal zone 40, and the radially external zone of The mounting points 50 are annular in shape. The radially external mounting point 50 includes notches / studs defining slots designed to fit onto load-bearing bars on the wheel rim. The friction zone 30, the free radially internal zone 40, and the radially external mounting point 50 are annular in shape.

[0044] As can be seen in [Fig.4], the two friction zones 30 of the friction faces 20 axially surround an inner zone 70 which is the core of the rotor disk 10.

[0045] For the implementation of the localized heat treatment process according to the invention, the disc, whether it is a stator disc 1 or a rotor disc 10, is positioned in an external tube 8 made of refractory graphite which acts as a reaction chamber and mold. An internal tube 9 made of refractory graphite can be arranged in the central annular opening 6 of the disc 1, for example in the case where it is necessary to heat the inner zone 7, 70 of the disc 1, 10 (Figures 5 to 7).

[0046] Fig. 6 shows a device comprising a stator disk 1, while Fig. 7 shows a device comprising a rotor disk 10.

[0047] Two flat graphite electrodes 11 are positioned in contact with the friction faces 2, 20 of the disc. A current is created between these two friction faces 2, 20 by applying a voltage differential. Under the effect of the current, the disc is rapidly heated throughout its volume. An axial force can also be maintained on the disc during the entire heating phase. For this purpose, the two flat electrodes 11 can also be used to transfer the pressing force to the disc.

[0048] The disc, the outer tube 8, the inner tube 9 and the electrodes 11 are arranged inside a hermetically sealed enclosure 12, into which an inert gas, such as nitrogen, is injected via an inert gas inlet 13.

[0049] A layer of electrical insulation 14, for example pyrolytic boron nitride, can be placed between the outer graphite tube 8 and the disc to be treated to prevent leakage currents to the tooling and maximize volumetric heating (Figures 8 to 11). Electrical insulation is all the more important when the material of the disc to be treated is a poor electrical conductor, as is the case with ceramic fillers. The use of electrical insulation 14 on part of the friction faces 2 makes it possible to limit the passage of current in the inner zone 7 of the disc or to the outer or inner zones of the disc. The heating is then heterogeneous with temperature fields corresponding to the electrical path in the disc 1.

[0050] To heat the external area of ​​the disk (i.e., the free radially external area 4 in the case of a stator disk or the radially external fixing area 50 in the case of a rotor disk), the external graphite tube 8 is not insulated and the areas of friction 3 and the flat part of the inner diameter (the fixing area 5 in the case of a stator disc or the free area 4 in the case of a rotor disc) are isolated.

[0051] To heat the internal area of ​​the disk (i.e., the radially internal mounting area 5 in the case of a stator disk or the radially internal area 40 in the case of a rotor disk), the outer graphite tube 8 is insulated, and the friction areas 3 and the flat part of the external area (i.e., the radially internal mounting area 5 in the case of a stator disk or the radially internal free area 40 in the case of a rotor disk) are insulated. The inner graphite tube 9, with a diameter equivalent to the diameter of the central opening 6, can be added to provide a heating element.

[0052] To heat the inner zone 7 of the disc and the friction zones 3, the graphite enclosure and the flat parts of the areas that are not friction zones (i.e. the fixing zone 5 and the free zone 4) are insulated.

[0053] Heating using electrodes 11 further reduces structural changes and high-temperature chemical reactions between the fillers, carbon fibers and carbon matrix, compared to heating through the walls, which is slower.

[0054] Due to its composition and structure, a C / C disk is an excellent electrical conductor, which can easily be heated by Joule heating. Localized treatment of the disk advantageously includes the application of an electrical insulator such as, by way of non-exhaustive example: - glass for heat treatment below 1200°C, - Pure quartz / silica for heat treatment between 1200°C and 1600°C, - Boron nitride for heat treatment under a neutral atmosphere, - Silicon nitride, - metallic nitrides (such as TiN, AIN), - oxides (such as alumina, mullite, HfO2, ZrO2).

[0055] The thickness of the electrical insulation layer is advantageously chosen taking into account the breakdown voltage of the insulation and the experimental conditions (such as voltage or pressure).

[0056] It is also possible to consider using an electrode with a shape adapted to the geometry of the area to be treated.

[0057] It is also possible to combine the two previous aspects by developing a "hybrid" tooling comprising conductive zones (electrodes) and insulating zones (press force application) adapted to the geometry of the workpiece being processed. It is possible to add heat dissipation zones in the tooling (cooling / heat sink) to accentuate thermal gradients and / or protect functional areas that do not want to be heated.

[0058] The manufacture of an aircraft brake disc based on carbon / carbon composite material generally includes the following steps: the manufacture of a preform including needle punching of oxidized polyacrylonitrile fibers, a carbonization step, matrix deposition, final heat treatment, and machining.

[0059] In particular, the manufacture of such discs usually includes a step of producing a fibrous preform in carbon fibers having a shape close to that of a disc to be manufactured and intended to constitute the fibrous reinforcement of the composite material, and the densification of the preform by a carbon matrix.

[0060] A well-known process for producing a carbon fiber fibrous preform includes layering fibrous layers of carbon precursor fibers, for example oxidized polyacrylonitrile (PAN), linking the layers together, for example by needle punching, and carrying out a carbonization heat treatment to transform the precursor into carbon.

[0061] The densification of the preform by a carbon matrix can be carried out by chemical vapor infiltration (CVI). Preforms are placed in a chamber into which a gaseous phase containing one or more carbon precursors, for example methane and / or propane, is introduced. The temperature and pressure in the chamber are controlled to allow the gaseous phase to diffuse within the preforms and form a solid deposit of pyrolytic carbon (PyC) by decomposition of the precursor(s).

[0062] Densification by a carbon matrix can also be carried out by liquid means, i.e. by impregnation of the preform by a carbon precursor, typically a resin, and pyrolysis of the precursor, several cycles of impregnation and pyrolysis being usually carried out.

[0063] A densification process called "heat-action" is also known, in which a preform of a disk to be densified is immersed in a bath of carbon precursor, for example toluene, and is heated, for example by coupling with an inductor, so that the precursor vaporized in contact with the preform diffuses within it to form a PyC deposit by decomposition.

[0064] A non-exhaustive list of examples of implementation of the method according to the invention is described below.

[0065] Example 1: Heat treatment of an external anti-oxidation protection

[0066] An anti-oxidation coating (AOC) is applied to a carbon / carbon composite disc using a liquid process (brush, spray gun) or a solid process (thermal spraying). The AOC can be applied to free areas (internal or external).

[0067] The coating is then consolidated / sintered / crystallized using the localized treatment process described above. The treatment can also produce a specific phase (chemical reaction between several components, crystallization, etc.). The Joule heating temperature can be between 500 and 1000°C, under a protective atmosphere (nitrogen, argon, or other neutral gas), and for a duration ranging from a few seconds to one hour. Example 2#: Reinforcement of a fixing area

[0068] A preform is produced by needle punching pre-oxidized polyacrylonitrile fibers, followed by a carbonization heat treatment. The preform can then be densified with a carbon matrix by CVI, heat treatment, or resin impregnation and pyrolysis.

[0069] The fastening zone is then reinforced by locally increasing its density. For this purpose, the fastening zone (lugs / notches) is impregnated with a high-carbon resin, such as phenolic resins, furfural, tars, coke, pitch, asphaltenes, cyanates and their derivatives, or benzoxazines. Rapid and localized heating of the fastening zone is then carried out using the localized treatment process described above, in order to pyrolyze the resin and subsequently manage the effluent gases. Pyrolysis can be performed at a temperature between 200 and 1000°C, for a duration of between 5 minutes and 4 hours. The higher the temperature, the shorter the duration (typically 4 hours at 200°C). The temperature ramp must be maximized while ensuring proper evacuation of the gaseous by-products. Purification, which is optional, can be carried out at a temperature between 800 and 1500°C.A graphitization step (baking carbon to obtain graphite) can be carried out at a temperature between 1500 and 2500°C, for a duration of between 2 minutes and 10 hours. Resin residues present on the friction areas / core of the disc are then removed by rinsing in a suitable solvent, followed by a final heat treatment and machining, and then the application of an anti-oxidation protective coating.

[0070] Example 3: Graphitization heat treatment of the disk core or free zone to increase oxidation resistance

[0071] The disk (stator disk or rotor disk) is disposed in the hermetically sealed enclosure, under a neutral gas (nitrogen N2 for example). A conductive layer 15 of electrical contact is disposed in the middle of the friction zones 3 of the friction faces 2. The conductive layers 15 are preferably arranged symmetrically with respect to the plane of symmetry of the disk passing through the disk, and which is perpendicular to the axis X of the disk 1. The electrical contact layers 15 can belong to the disk 1 or to the flat electrodes 11. In addition, an electrical insulating layer 14 is disposed over the rest of the surface of the disk 1, i.e. in particular over the areas which are not friction areas, so as to electrically insulate the rest of the disk from the flat electrodes 11 ([Fig.8]).

[0072] The flat graphite electrodes 11 are brought together so as to make contact with the electrical contact layers 15 and the electrical insulating layer 14 ([Fig.9]).

[0073] An electric current is created between the two faces by applying a potential difference using a voltage or current generator G. Under the effect of the current, the disk is heated by Joule effect at very high speed in its volume, in the hot zone 16 ([Fig. 10]).

[0074] The two flat electrodes 11 are then removed ([Fig. 11]) and the disk 1 is removed from the enclosure 12 ([Fig. 12]). The disk 1 thus presents a heat-treated area 17 located mainly in the inner area 7 of the disk ([Fig. 12]). Example 4#: Adding local loads

[0075] A preform is produced by needle punching oxidized polyacrylonitrile fibers, followed by a carbonization heat treatment.

[0076] The preform is then densified with a carbon matrix. Partial densification is achieved (density between 0.5 and 1.6). Ceramic fillers or a ceramic precursor are introduced locally into the attachment zone (the pins / notches). A Joule effect heat treatment according to the invention is then carried out at a temperature between 600 and 1700°C, and localized to the attachment zone. The mass fraction of filler added is between 1 and 20%.

[0077] The rest of the part is then densified by CVI or PIP (“Polymer Impregnation and Pyrolysis” in English).

[0078] A final heat treatment and machining followed by an anti-oxidation protective coating complete the process.

[0079] The filler can be introduced by various suitable processes. By way of example, but not exhaustively, a liquid precursor or a filler dispersion can be added by impregnation under vacuum or pressure, preparation of the material by washing with a surfactant then localized application followed by vacuuming to allow the filler to penetrate.

[0080] The localized introduction of the ceramic filler can thus be achieved by impregnating a ceramic precursor via the sol / gel method. The partially densified material can be impregnated under vacuum with the precursor sol. Gelation of the core is achieved by localized heating of the part to a temperature in the range of 50-120°C, depending on the impregnation solvent. The precursor is then removed. If the precursor is not gelled by rinsing, the excess precursor can be removed using one or a combination of the following techniques: ultrasonic solvent bath, rinsing with a surfactant or precursor chelating agent solution, or rinsing with a solvent introduced into the material by forced flow (convection / pressure or vacuum). Pyrolysis / conversion of the precursor to ceramic is achieved by applying Joule heating at a temperature between 500 and 1600°C for a duration ranging from 3 seconds to 20 minutes.

[0081] The invention thus allows a localized method of adjusting the properties of the aircraft brake disc, making it possible to adapt the material present in each functional zone to the constraints it faces during its life cycle: - for the fixing zone (pins / notches): mechanical properties, oxidation (catalytic and thermal), thermal conductivity, - for the friction zone: tribological behavior, resistance to wear and incidentally to oxidation, - for the free zone: oxidation (catalytic and thermal), emissivity (radiation), - for the disc core: heat capacity, diffusivity / conductivity.

[0082] The process allows control of the temperature fields within the disk, the mechanical pressure applied to the disk, and the chemical environment in which the disk is placed (neutral gas, precursor, oxidant).

Claims

Demands

1. A localized heat treatment method for an aircraft brake disc (1, 10) comprising a composite material having a matrix reinforced by carbon fibers, the disc (1, 10) being provided with two friction faces (2, 20) each located on one side of the disc (1, 10), the method being characterized in that it comprises: - making electrical contact of an electrode (11), on each side of the disc (1, 10), with a treatment area (17) of the disc (1, 10), an electrical insulator (14) being disposed on at least one friction face (2, 20), in a vicinity of the treatment area (17), and - generating an electric current between the two electrodes (11), so as to heat said treatment area (17) by Joule effect.

2. A method according to claim 1, characterized in that the composite material comprising a matrix reinforced by carbon fibers is a carbon / carbon (C / C) composite material, a C / C-SiC composite material, a C / SiC composite material, or a C / ceramic composite material.

3. A method according to claim 1 or 2, characterized in that each friction face (2, 20) comprises a friction zone (3, 30), a fixing zone (5, 50) and a free zone (4, 40), and in that the area to be treated (17) comprises a part of each friction zone (3, 30), a part of each fixing zone (5, 50), or a part of each free zone (4, 40).

4. Method according to claim 3, characterized in that each friction zone (3, 30) extends radially between a fixing zone (5, 50) and a free zone (4, 40).

5. Method according to claim 4, characterized in that the disk (1, 10) is a stator disk (1), each fixing zone (5) being a radially internal zone intended to be fixed to an axle of a landing gear, and each free zone (4) being a radially external zone.

6. Method according to claim 4, characterized in that the disc (1, 10) is a rotor disc (10), each attachment zone (50) being a radially external zone intended to be attached to a rim of a wheel of a landing gear, and each free zone (40) being a radially internal zone.

7. A method according to any one of claims 1 to 6, characterized in that the area to be treated (17) is coated with an anti-oxidation protection or an anti-oxidation protection precursor mixture before heating the area to be treated by Joule effect.

8. A method according to any one of claims 3 to 6, characterized in that the area to be treated (17) comprises a part of each fixing area (5, 50), and in that each fixing area (5, 50) is coated with resin before heating the area to be treated (17) by Joule effect.

9. A method according to any one of claims 3 to 6, characterized in that the area to be treated (17) comprises a part of each fixing area (5, 50), and in that ceramic fillers or a ceramic precursor are introduced into the area to be treated (17) before Joule heating of the area to be treated (17).

10. A method according to any one of claims 1 to 9, characterized in that the disc (1, 10) comprises an inner zone (7, 70) located in the thickness of the disc (1, 10) and in that the area to be treated (17) comprises a part of the inner zone (7, 70).

11. Device for implementing a localized treatment process according to any one of claims 1 to 10, characterized in that it comprises a hermetically sealed enclosure (12) under a neutral gas atmosphere, inside which is disposed an aircraft brake disc (1, 10) comprising a composite material having a matrix reinforced by carbon fibers, the disc (1, 10) being provided with two friction faces (2, 20) each located on one side of the disc (1, 10), and in that the device further comprises two electrodes (11) connected to an electric current generator and suitable for being applied each on one side of the disc (1, 10) to a treatment area (17) of the disc, an electrical insulator (14) being disposed on at least one friction face (2, 20) in a vicinity of the treatment area (17).

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