Process for the production of a thermoplastic coating on a composite material

Abstract

The present invention relates to a process for producing a composite material (1) composed of carbon fibers (111) with a thermosetting organic matrix (112) coated with a thermoplastic material (12).

Description

Description Title: Process for producing a thermoplastic coating on a composite material Technical field

[0001] This disclosure relates to the field of aeronautics, in particular to thermosetting organic matrix carbon fiber composite materials used in this field. Prior art

[0002] Thermosetting organic matrix carbon fiber composite materials have properties (strength, lightness, etc.) such that they are increasingly used in the aeronautics sector, for example for engine fan blades or nacelle casings.

[0003] However, these composite materials have weaknesses such as low abrasion resistance, low electrical conductivity and low heat resistance. To overcome these weaknesses, it is known to deposit a metallic coating on the surface of these composite materials.

[0004] These composite materials are particularly sensitive to heat. In thermal spraying, the heat input to the substrate comes from two sources: the heat provided by the fluid constituting the spray plume (plasma, flame, hot compressed air, etc.) on the one hand, and the heat provided by the particles constituting the deposit (cooling to ambient temperature and latent heat of solidification where applicable). It is therefore not possible to deposit any metal coating with any deposition technique. For example, flame spraying, which is increasingly used in the aeronautical field for coating deposition on materials, is only rarely used to deposit a metal coating on thermosetting organic matrix carbon fiber composite materials.Indeed, this technique is very difficult to implement without damaging these composite materials because it can bring excessive heat to the composite material and alter their properties. Currently, the most widely used coatings associated with the thermal spraying technique are, respectively, zinc and electric arc wire spraying. Indeed, zinc has a relatively low melting point and the electric arc wire spraying technique brings little heat to the substrates.

[0005] The adhesion of the coating to the composite material must be as high as possible so that the coating remains adherent to the substrate when the composite part is stressed in service. This is especially true when the composite material is used on parts of an aircraft or engine that are particularly exposed to deformation, shocks or erosion, for example. The adhesion between the zinc coating deposited by the electric arc spraying technique and the composite material is in the order of 9-10 MPa in the best case. This fairly low adhesion value limits the use of zinc-coated thermosetting organic matrix carbon fiber composite materials to certain aeronautical applications that are not subject to much mechanical stress, such as stators not in direct contact with a flow of erosive particles. To increase the scope of aeronautical applications of these composite materials, it is therefore necessary to increase the adhesion of the coating on these composite materials.

[0006] A commonly used technique to increase the adhesion of a coating to a material is sandblasting. Sandblasting is a technique that imparts a certain roughness to the sanded material. This roughness increases the interface between the coating and the material and therefore increases adhesion. This roughness also creates attachment sites for coating particles projected onto the material. Sandblasting cannot be effectively implemented on thermosetting organic matrix carbon fiber composite materials. Indeed, these composite materials are not very plastic and the carbon fibers can easily be damaged during sandblasting.

[0007] There is therefore a need for an effective solution to increase the adhesion of a coating on a thermosetting organic matrix carbon fiber composite material to increase the scope of application of these materials in the aeronautical field.

[0008] It is therefore to the credit of the inventors that they found that it was possible to meet this need with the help of a new coating. Summary

[0009] A method of producing a multi-layer material is provided comprising a step a) of flame spraying a thermoplastic material onto a first layer of thermosetting organic matrix carbon fiber composite material to form a second layer comprising the thermoplastic material on the first layer.

[0010] Unexpectedly, since it is known that the chemical affinity between the thermosetting organic matrix and the thermoplastic material is relatively low, the adhesion between the first layer and the second layer is advantageously very high when the latter is a flame-sprayed thermoplastic material. This adhesion is higher than the adhesion between a thermosetting organic matrix carbon fiber composite material and a zinc coating deposited by the electric arc spraying technique. The multilayer material produced by the process of the invention can therefore be used in numerous new applications, particularly in the aeronautical field.

[0011] Furthermore, to form the second layer, it is not necessary to heat the thermoplastic material to temperatures that could damage the composite material of the first layer. Thus, the deposition of certain materials by the flame spray technique to form the second layer may not alter the properties of the composite material. This is particularly true when the spray distance is large enough to minimize the heat input by the flame and when the selected material has a sufficiently low melting point, for example 186°C

[0012] The multilayer material produced by the method of the invention is also economical to produce. Indeed, the flame spraying technique is conventionally implemented in the aeronautical field so that the method of the invention does not require investment in new production equipment.

[0013] According to another aspect, there is provided a multi-layer material comprising a first layer of thermosetting organic matrix carbon fiber composite material and a second layer of thermoplastic material in contact with the first layer.

[0014] According to another aspect, the use of a multi-layer material comprising a first layer of thermosetting organic matrix carbon fiber composite material and a second layer of thermoplastic material in contact with the first layer in the aeronautical field is proposed.

[0015] According to another aspect, there is provided an aeronautical part at least partly manufactured in the multilayer material comprising a first layer of thermosetting organic matrix carbon fiber composite material and a second layer of thermoplastic material in contact with the first layer. Brief description of the drawings

[0016] Other features, details and advantages will become apparent upon reading the detailed description below, and upon analyzing the attached drawings, in which: Fig. 1

[0017] [Fig. 1] shows a schematic representation of the multilayer material according to the invention. Fig. 2

[0018] [Fig. 2] shows a schematic representation of the process for producing the multilayer material of the invention. Description of the embodiments

[0019] The invention is described in connection with [Fig.1] and [Fig.2].

[0020] A method for producing a multilayer material 1 is proposed comprising a step a) of flame spraying a thermoplastic material onto a first layer 11 of carbon fiber composite material 111 with a thermosetting organic matrix 112 to form a second layer 12 comprising the thermoplastic material on the first layer 11.

[0021] The second layer 12 comprises a first surface in contact with a surface of the first layer 11 and a second surface opposite the first surface. The first surface of the second layer 12 may partially or completely cover, in particular completely, the surface of the first layer 11 with which it is in contact.

[0022] For the purposes of the present invention, the term "thermoplastic material" means a material having the property of softening when heated to a temperature above its glass transition temperature and which becomes hard again when cooled to a temperature below its glass transition temperature.

[0023] For the purposes of the present invention, the term "thermosetting organic matrix carbon fiber composite material" means a heterogeneous material comprising carbon fibers which serve as reinforcement and a thermosetting organic matrix which serves as a binder and gives the material its shape. This material is also referred to as "composite material" in the present application.

[0024] According to one embodiment, the surface of the composite material onto which the thermoplastic material is sprayed may be covered, totally or partially, in particular partially, with a plastic film, a paint or their combinations. The plastic film may, for example, be a polyurethane film. The paint may, for example, be an aeronautical paint. According to this embodiment, during step a), the thermoplastic material may be sprayed onto this plastic film or this paint.

[0025] For the purposes of the present invention, the term "thermosetting organic matrix" designates a matrix obtained from thermosetting polymers, i.e. polymers which become, after polymerization, infusible and insoluble.

[0026] For the purposes of the present invention, the term "flame spraying" designates a thermal spraying process consisting of introducing a material into an oxy-fuel flame and transporting it using the kinetic energy transmitted by the combustion gases to a substrate on which it is deposited.

[0027] The thermoplastic material used in spraying step a) of the process of the present invention may have a glass transition temperature of less than 200°C, in particular less than 100°C, and optionally a melting temperature of less than 250°C, in particular less than 200°C.

[0028] Advantageously, a thermoplastic material having such a glass transition temperature, and possibly such a melting temperature, can be softened and deposited on the composite material without altering the mechanical properties of said composite material.

[0029] For the purposes of the present invention, the term "glass transition temperature" means the temperature below which the thermoplastic material is in the glassy state and above which the chains of the thermoplastic material are mobile.

[0030] The thermoplastic material may, for example, be chosen from polyethylene, polypropylene, polyamide 11, polyetheretherketone (PEEK) and mixtures thereof, in particular polyamide 11.

[0031] For the purposes of the present invention, the term "polyamide 11" designates the different shades of polyamide 11 and their mixtures.

[0032] These thermoplastic materials are commonly used in the aeronautical field. Those skilled in the art will therefore know how to implement them in the process of the present invention. In particular, those skilled in the art will know how to choose the projection conditions making it possible to limit the maximum heat input on the composite substrate and projection systems (nozzles in particular) adapted to these heat-sensitive materials.

[0033] In addition, the production cost of the material obtained by the method of the present invention is relatively low because the cost of thermoplastic materials is low.

[0034] Furthermore, the second layer obtained by the process of the present invention is of interest in aeronautical applications because it has a very low density, of the order of 1.03 g / cm 3 .

[0035] The thermoplastic material can be used in the projection step a) of the process of the present invention in powder form, in wire form, in particular in powder form.

[0036] A thermoplastic material, in the form of a powder having a particle size of between 10 pm and 500 pm, in particular between 50 pm and 250 pm, very particularly between 100 pm and 130 pm, is entirely suitable for implementation in step a) of projection of the process of the present invention.

[0037] According to the invention, the particle size of the powder is determined according to ISO 13320:2020.

[0038] The thermosetting organic matrix 112 of the composite material may be obtained from epoxy polymer, polybismaleimide or cyanate ester, or from a thermoplastic resin based on polyaryletherketone, polyethylenimine (PEI), poly(phenylene sulfide) (PPS), polyimide (PI) or mixtures thereof.

[0039] Advantageously, the adhesion between the first layer 11 of composite material listed above and the second layer 12 comprising a thermoplastic material listed above is higher than the adhesion between the zinc coating deposited by the conventional electric arc spraying technique and a composite material.

[0040] Flame spraying can be carried out, during spraying step a), using an oxy-gas torch, i.e. a torch using two gases to generate the flame: oxygen and a combustible gas. In particular an oxyacetylene torch (using oxygen and acetylene) or an oxypropane torch (using oxygen and propane), especially an oxyacetylene torch.

[0041] Advantageously, the use of these torches makes it possible to limit the deterioration of the thermoplastic material used during step a) of projection.

[0042] This is especially true if the torch is equipped with a nozzle specific to heat-sensitive materials such as thermoplastics. Indeed, such a nozzle, known to those skilled in the art, limits direct contact between the thermoplastic material and the flame, which can heat up to 3000°C.

[0043] A nozzle specific to heat-sensitive materials includes: - an axial channel allowing the projection of the heat-sensitive material using a carrier gas which can be nitrogen or argon, - first annular channels arranged around and equidistant from the axial channel allowing an annular projection of a sheathing gas, which may be nitrogen or argon, around the heat-sensitive material projected by the axial channel, and - second annular channels arranged around and equidistant from the axial channel allowing an annular projection of the gases generating the flame, the distance between the second annular channels and the axial channel being greater than the distance between the first annular channels and the axial channel.

[0044] Thus, according to a specific embodiment, the torch is equipped with a nozzle specific to heat-sensitive materials. Such a nozzle is, for example, the SSM40 nozzle of the CastoDyn DS8000 torch.

[0045] Typically, the oxygen flow rate in the torch can be between 15 l / min and 25 l / min, especially between 19 l / min and 20 l / min.

[0046] Typically, the flow rate of the other gas, particularly acetylene or propane, more particularly acetylene, into the torch may be between 7 l / min and 11 l / min, particularly between 9 l / min and 10 l / min.

[0047] The projection distance, i.e. the distance between the thermoplastic material outlet end of the torch and the first layer 11, may be between 200 mm and 400 mm, in particular between 280 mm and 320 mm.

[0048] Advantageously, such a distance makes it possible to control the temperature of the thermoplastic material so that it does not damage the composite material of the first layer 11 while keeping the thermoplastic material softened so that it adheres to the first layer 11. This distance also makes it possible, by using ad hoc additional cooling, to limit the heat input by the flame to the substrate so as not to damage it.

[0049] Typically, the flow rate of the thermoplastic material in the torch can be between 10 g / min and 50 g / min, particularly between 15 g / min and 25 g / min.

[0050] [Fig. 2] illustrates an embodiment of the method according to the invention. In this embodiment, step a) is carried out using a torch C generating a flame F directed towards the multilayer material 1 and comprising means M allowing its relative movement with respect to the multilayer material 1. During step a), the thermoplastic material, in the form of powder P, is projected by the torch C into the flame F towards the multilayer material 1 in order to form the second layer 12 on the first layer 11.

[0051] The method of the present invention may further comprise a step b) of forming by thermal spraying a third functionalized layer 13 on a portion of the surface, in particular over the entire surface, of the second layer 12 so that this portion of the surface, in particular the entire surface, is arranged between the first layer 11 and the third functionalized layer 13.

[0052] According to one embodiment, the surface of the second layer 12 on which the third functionalized layer 13 is formed is the second surface opposite the first surface.

[0053] Advantageously, the adhesion between the third functionalized layer 13 and the first layer 11, via the second layer 12, is higher than the adhesion between the zinc coating deposited by the conventional electric arc spraying technique and a composite material.

[0054] Thus, the multilayer material 1 produced by the method of the invention comprising the third functionalized layer 13 can be used in numerous new applications, in particular in the aeronautical field.

[0055] This is all the more true since the third functionalized layer 13 makes it possible to adapt the multilayer material 1 produced by the method of the present invention according to its intended application, in particular in the aeronautical field.

[0056] Thus the third functionalized layer 13 comprises a material chosen from a metal, an oxide, a nitride, a carbide and their combinations.

[0057] For example, the metal may be selected from copper, stainless steel, titanium, zinc, aluminum, and mixtures thereof, particularly zinc. The metal may be in pure form or in alloy form.

[0058] Copper, for example, makes it possible to improve the electrical conductivity of the multilayer material 1 produced by the method of the present invention. Thus, this multilayer material 1 can be used to dissipate the electrical energy of lightning striking an aircraft or as a heating element for de-icing an aircraft.

[0059] Stainless steel greatly improves resistance to erosion and abrasion by air particles impacting, for example, the surface of an aircraft engine blade.

[0060] The third functionalized layer 13 comprising a metallic material may be a reinforcement made of metallic material, in particular a reinforcement made of metallic material of a fan blade, more particularly a reinforcement made of metallic material of the leading edge of a fan blade.

[0061] By means of the method of this embodiment, the metal material reinforcement can be easily and quickly adhered to the fan blade. In addition, the adhesion between the metal material reinforcement and the fan blade, via the second layer 12, is very high.

[0062] Step b) of forming by thermal spraying can be carried out by flame spraying, supersonic flame spraying ("High Velocity Oxy-Fuel" according to English terminology) by blown arc plasma, by electric arc spraying, or by cold dynamic spraying ("Cold spray" according to English terminology), in particular by flame spraying, by electric arc spraying or by cold dynamic spraying, more particularly by cold dynamic spraying.

[0063] The implementation of these techniques for spraying a metal onto a thermoplastic material coating is known to those skilled in the art. Thus, those skilled in the art know how to implement step b).

[0064] According to one embodiment, the method according to the invention may comprise, alternatively to step b), a step c) of bonding a reinforcement, in particular a reinforcement made of metallic material, to a portion of the surface of the second layer 12 so that this portion of the surface is arranged between the first layer 11 and the reinforcement.

[0065] The multilayer material 1, produced by the method of this embodiment, may be a fan blade, in particular a fan blade comprising a leading edge on which the reinforcement is bonded.

[0066] By means of the method of this embodiment, the reinforcement can be easily and quickly bonded to the fan blade. In addition, the adhesion between the reinforcement and the fan blade, via the second layer 12, is very high.

[0067] Before the spraying step a) of the method of the present invention, the first layer 11 of carbon fiber composite material 111 with a thermosetting organic matrix 112 may undergo a pretreatment step. This step may, for example, be a preheating to a temperature below the glass transition temperature of the thermoplastic material, in particular to a temperature below 100°C, more particularly between 50°C and 80°C.

[0068] According to another aspect, a multilayer material 1 is provided comprising a first layer 11 of carbon fiber composite material 111 with a thermosetting organic matrix 112 and a second layer 12 of thermoplastic material in contact with the first layer 11.

[0069] This multilayer material 1 can be obtained by the method of the present invention.

[0070] The second layer 12 of the multilayer material 1 comprises a first surface in contact with a surface of the first layer 11 and a second surface opposite the first surface. The first surface of the second layer 12 may partially or completely cover, in particular completely, the surface of the first layer 11 with which it is in contact.

[0071] The multilayer material 1 of the invention can therefore be used in numerous new applications, in particular in the aeronautical field.

[0072] The thickness of the second layer 12 depends on the implementation of the projection step a) of the method of the present invention. It may, for example, be between 50 pm and 3000 pm, in particular between 75 pm and 1500 pm, very particularly between 100 pm and 200 pm.

[0073] Advantageously, a thickness in these ranges ensures strong adhesion between the first layer 11 and the second layer 12. In addition, the highest thicknesses in these ranges make it possible to increase the capacity for accommodating stresses by the multilayer material 1 provided by the very high deformability of the second layer 12 made of thermoplastic material and / or to improve the shock absorption capacity of the multilayer material 1.

[0074] The composite material of the first layer 11 is as described above in connection with step a) of projection of the method of the present invention.

[0075] The thermoplastic material of the second layer 12 is as described above in connection with the spraying step a) of the method of the present invention.

[0076] The multilayer material 1 may further comprise a plastic film, a paint or combinations thereof, between the first layer 11 and the second layer 12. The plastic film may, for example, be a polyurethane film. The paint may, for example, be an aeronautical paint.

[0077] The multilayer material 1 may further comprise a third functionalized layer 13 on a portion of the surface, in particular over an entire surface, of the second layer 12 so that this portion of the surface, in particular this entire surface, is arranged between the first layer 11 and the third functionalized layer 13.

[0078] According to one embodiment, this surface of the second layer 12 is the second surface opposite the first surface.

[0079] This functionalized layer 13 makes it possible to adapt the multilayer material 1 according to its application.

[0080] The material of the functionalized layer 13 is as described above in connection with step b) of formation of the method of the present invention.

[0081] The use of the multilayer material 1 as defined above in the aeronautical field is also proposed.

[0082] For example, the multilayer material 1 can be used as an electrical energy dissipating element, a heating element for defrosting, an abrasion or erosion resistant element.

[0083] Furthermore, an aeronautical part is proposed which is at least partly manufactured from the multilayer material 1 as defined above.

[0084] For example, the aeronautical part may be at least partly manufactured in the multilayer material 1 comprising the third functionalized layer 13 which is a reinforcement in metallic material, said aeronautical part being a fan blade.

[0085] In particular, the fan blade may be a fan blade comprising a leading edge to which the reinforcement is bonded.

Claims

Claims

1. A method of producing a multilayer material (1) comprising: a step a) of flame spraying a thermoplastic material onto a first layer (11) of carbon fiber composite material (111) with a thermosetting organic matrix (112) to form a second layer (12) comprising the thermoplastic material on the first layer (11).

2. A method according to claim 1, wherein the thermoplastic material has a glass transition temperature of less than 200°C and optionally a melting temperature of less than 250°C.

3. A method according to claim 1 or claim 2, wherein the thermoplastic material is selected from polyethylene, polypropylene, polyamide 11, polyetheretherketone and mixtures thereof.

4. Method according to any one of claims 1 to 3 further comprising a step b) of forming by thermal projection a third functionalized layer (13) on a portion of the surface of the second layer (12) so that this portion of the surface is arranged between the first layer (11) and the third functionalized layer (13).

5. Method according to claim 4 in which the third functionalized layer (13) is a reinforcement made of metallic material.

6. A method according to claim 5, wherein the multilayer material (1) is a fan blade to which the metallic material reinforcement adheres.

7. Multilayer material (1) comprising a first layer (11) of carbon fiber composite material (111) with a thermosetting organic matrix (112) and a second layer (12) of thermoplastic material in contact with the first layer (11).

8. Material according to claim 7 wherein the thermoplastic material of the second layer (12) has a glass transition temperature of less than 200°C and optionally a melting temperature of less than 250°C.

9. Material according to claim 7 or claim 8 in which the thermoplastic material of the second layer (12) is chosen from polyethylene, polypropylene, polyamide 11, polyetheretherketone and mixtures thereof.

10. Material according to any one of claims 7 to 9 further comprising a third functionalized layer (13) on a portion of the surface of the second layer (12) such that this portion of the surface is disposed between the first layer (11) and the third functionalized layer (13).

11. The material of claim 10 wherein the third functionalized layer (13) comprises a material selected from a metal, an oxide, a nitride, a carbide and combinations thereof.

12. Material according to claim 10 or claim 11 in which the third functionalized layer (13) is a reinforcement of metallic material.

13. Use of a multilayer material (1) as defined in any one of claims 7 to 12 in the aeronautical field.

14. Aeronautical part at least partly manufactured from the material according to one of claims 7 to 12.

15. Aeronautical part according to claim 14 and at least partly manufactured from the material according to claim 12, the aeronautical part being a fan blade, in particular a fan blade comprising a leading edge on which the reinforcement of metallic material adheres.

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