Protective coating for a turbine engine blade

Abstract

The invention relates to a blade (100) made of an organic matrix composite material, at least part of the leading edge (111) whereof is covered with a metal foil (131), the blade being characterised in that at least part of the metal foil is coated with at least: - a first layer comprising a first material, the first material being aluminium oxide, a metal carbide or a metal nitride, the first layer being arranged directly on the leading edge of the body of the blade; and - if the first material is not aluminium oxide, a second layer comprising a second material, the second material comprising a metal nitride, a metal carbide, a metal carbonitride or a metal silicide that is different from the first material, the second layer being arranged directly on the first layer.

Description

Description Title of the invention: Protective coating for a turbomachine blade. Technical Field

[0001] This disclosure relates to a protective coating for a turbomachine blade made of composite material. Prior art

[0002] Polymer matrix composite materials, also known as organic matrix, are known for the production of cold section elements of aeronautical turbomachines, such as fan blades. These materials generally have a lower weight than metal alloys at the same performance level, which gives them an industrial advantage for applications where weight issues are crucial.

[0003] This is particularly the case in the aeronautics sector, and more specifically in turbomachinery, for which reducing the overall mass contributes to a reduction in fuel consumption and therefore to a significant reduction in polluting emissions.

[0004] Fan blades must meet important regulations, including resisting erosion and possible impacts caused by elements external to the engine.

[0005]

[0006] For this purpose, it has been proposed in the prior art to bond metal foils to the leading edges of turbine blades made of polymer matrix composite material, in order to improve its properties, in particular to improve resistance to impacts encountered in operation (impacts from birds, hailstones or debris).

[0007] However, such a solution requires ensuring excellent durability of the metal foils over time, otherwise the protection it provides would be lost.

[0008] It would indeed be beneficial to have a method ensuring an improvement in the lifespan of fan blades and their metal foils. Statement of the invention

[0009] The invention aims to propose a solution to the problem described above.

[0010] To this end, it proposes, according to a first of its aspects, a blade made of organic matrix composite material comprising a blade body extending in a longitudinal direction between an internal end and an external end and in an axial direction between a leading edge and a trailing edge, at least a portion of the leading edge of the blade being covered with a metal foil, the blade being characterized in that at least a portion of the metal foil is coated with at least: - a first layer comprising a first material, the first material being aluminum oxide, a metal carbide or a metal nitride, the first layer being disposed directly on the leading edge of the blade body; and - in the case where the first material is not aluminum oxide, a second layer comprising a second material, the second material comprising a metal nitride, a metal carbide, a metal carbonitride or a metal silicide different from the first material, the second layer being arranged directly on the first layer.

[0011] The inventors determined that such a coating would make it possible to obtain a turbomachine blade which has a better protected leading edge than the turbomachine blades of the prior art, and which thus has better resistance to erosion, oxidation, corrosion and impacts than the leading edges of the prior art.

[0012] Erosion resistance can be assessed by a method known as three-dimensional measurement, also known as "TDM" for the acronym in English "Three-Dimensional Machine" applied to direct measurements obtained on a blade after wear cycles, for example after at least 4000 wear cycles.

[0013] Impact resistance can be assessed by the TDM technique applied to measurements obtained on a blade after an impact.

[0014] In one embodiment, the first material is aluminum oxide AI2O3.

[0015] In one embodiment, the protective coating disposed on the metal foil comprises only one layer, i.e. a first layer, and this comprises aluminum oxide AI2O3 as the first material.

[0016] In such an embodiment, less complex blades are obtained than the blades of the prior art. In addition, the aluminum oxide coating has excellent cohesion with the metallic material of the foil.

[0017] It is to the credit of the inventors to have identified on the one hand that the aluminum oxide could on the one hand be placed simply on a metal foil of a blade made of organic matrix composite material and on the other hand that it allows an improvement in the mechanical and chemical resistance properties compared to an embodiment comprising only a metal foil.

[0018] In one embodiment, the protective coating disposed on the metal foil comprises: - a first layer comprising a first material, the first material being a metal carbide or a metal nitride, the first layer being disposed directly on the leading edge of the blade body; and - a second layer comprising a second material, the second material comprising a metal nitride, a metal carbide, a metal carbonitride or a metal silicide different from the first material, the second layer being arranged directly on the first layer.

[0019] Such an embodiment provides excellent protection of the leading edge.

[0020] The first material is chosen to have excellent adhesion with the metallic foil but is also a transition material to allow the second material to adhere.

[0021] The second material is chosen to have, on the one hand, excellent cohesion with the first material and, on the other hand, excellent properties of resistance to erosion, corrosion, oxidation and impacts.

[0022] In one embodiment, the first layer may contain from 60 to 80% by mass of the first material.

[0023] In one embodiment, the first material is a metal carbide or a metal nitride, the metal being selected from tungsten W, titanium Ti or chromium Cr.

[0024] In one embodiment, the first material is a binary compound, i.e., it is composed only of a metal and another element selected from carbon or nitrogen.

[0025] In one embodiment, the first material is selected from titanium nitride TiN, chromium nitride CrN and tungsten carbide WC.

[0026] In one embodiment, the second layer may contain from 60 to 80% by weight of the first material.

[0027] In one embodiment, the second material is a metal nitride, a metal carbide, or a metal silicide.

[0028] For example, the second material is selected from aluminum titanium nitride TiAIN, aluminum chromium nitride CrAIN, aluminum titanium silicide TiAISi, carbon-enriched tungsten carbide WCC.

[0029] In one embodiment, the second material is a metal carbonitride and is further a quaternary compound, i.e., it is composed of four elements, one being a metal, another being carbon, a third being nitrogen.

[0030] For example, the second material can be selected from titanium aluminum carbonitride TiAICN, chromium aluminum carbonitride CrAICN.

[0031] In one embodiment, the second material comprises a metal nitride, a metal carbide, a metal carbonitride, wherein the metal or at least one of the metals is the same as the metal of the first material.

[0032] For example, the first material / second material pair can be chosen from the pairs TiN / TiAIN, CrN / CrAIN, WC / WCC, TiN / TiAISi, TiN / TiAICN, CrN / CrAICN, TiC / TiCAIN.

[0033] In one embodiment, the coating may have a thickness of less than or equal to 200 μm, or even between 5.0 and 10.0 μm.

[0034] It is to the inventors' credit that they determined that such a thickness is an excellent compromise between the weight of the coating and ensuring that the coating thickness is sufficient to provide the leading edge with sufficient protection to meet aeronautical requirements.

[0035] Preferably, the coating covers the metal foil of the leading edge over the entire height of the blade.

[0036] In other words, in one embodiment, the coating is present on the metal foil from the leading edge from the inner end to the outer end.

[0037] Alternatively, the coating may cover only a portion of the metal foil on the leading edge.

[0038] In fact, the inventors have noted that the metal foil on the leading edge exhibits greater wear the closer one is to the outer end of the blade.

[0039] Also, in one embodiment the metal foil of the leading edge is coated over 75% of its upper height, or even 50% of its upper height.

[0040] The expression “X% of the upper height of the leading edge” is intended to characterize that the coating is arranged only over X% of the length of the metal foil of the leading edge starting from the upper end.

[0041] This provides excellent protection for the most sensitive parts of the metal foil on the leading edge, while reducing the overall mass by eliminating the coating where the stresses are less significant, i.e. near the inner end of the blade.

[0042] In one embodiment, the composite material blade may be a fan blade or a propeller blade.

[0043] In both cases, as described above, the leading edge of the fan blade or propeller blade is coated with metal foil.

[0044] In one embodiment, the coating may cover, in addition to the leading edge, a portion of the upper surface and / or the lower surface.

[0045] Preferably the portion of the intrados and / or extrados covered by the coating does not exceed a few millimeters, for example 5.0 mm.

[0046] In one embodiment, the metal foil itself covers, in addition to the leading edge, a portion of the extrados and / or the intrados and the coating is thus entirely arranged on the metal foil.

[0047] Preferably, the portion of the intrados or extrados covered by the metal foil does not exceed a few millimeters, for example 5.0 mm.

[0048] In one embodiment, the metal foil may comprise a titanium alloy, for example a titanium alloy comprising aluminum and vanadium, such as that commonly referred to as TA6V in the field of titanium alloys.

[0049] According to another of its aspects, the invention relates to a method of manufacturing a blade as described above, the method comprising at least the following steps: - a step of depositing a first material directly on the metal foil of a blade made of organic matrix composite material, at least part of the leading edge of which is intended to be covered by a metal foil, the first material being aluminum oxide, a metal carbide or a metal nitride; and - in the case where the first material is not aluminum oxide, a step of depositing a second layer of a second material on a portion coated with a first layer, the second material comprising a metal nitride, a metal carbide, a metal carbonitride or a metal silicide different from the first material; - the bonding of the metal foil to the leading edge of a blade made of organic matrix composite material.

[0050] The inventors propose by this process a solution to obtain a blade with the advantages already described above for the blade itself.

[0051] In particular, this embodiment makes it possible to obtain a fan blade that is more resistant to erosion and impacts than a blade of the prior art.

[0052] In one embodiment, the step of bonding the metal foil to the leading edge of the blade made of organic matrix composite material can be carried out before the step of depositing the first material.

[0053] This embodiment allows for a blade close to the final part as soon as the coating stage is complete.

[0054] Alternatively, the step of bonding the metal foil to the leading edge of the blade made of organic matrix composite material can be carried out after the step of depositing the first material, and where appropriate after the step of depositing the second material.

[0055] This embodiment makes it possible in particular to work at higher temperatures for deposition operations, without risk of damaging the blade or the connection between the foil and the blade.

[0056] In one embodiment, the step of depositing the first layer can be carried out by sol-gel deposition, by laser deposition, by physical vapor deposition, in particular by magnetron sputtering or by thermal projection.

[0057] In a particular embodiment, where the first material is aluminum oxide AI2O3, the deposition can be carried out by sol-gel deposition, by laser deposition or even by thermal spraying.

[0058] Indeed, these methods are particularly suitable for the deposition of aluminum oxide and allow the choice of the deposition process best suited to the desired thickness of the coating.

[0059] In particular, a sol-gel deposition method can be chosen for a coating whose thickness is between 5.0 pm and 10 pm and a process by thermal spraying for a coating with a thickness between 100 pm and 200 pm.

[0060] In one embodiment, the step of depositing the first layer and, where appropriate, the second layer can be carried out by a physical vapor deposition method.

[0061] In one embodiment, the physical vapor deposition method may be magnetron sputtering.

[0062] In this embodiment, the deposition of the first material and / or the second material may be carried out by magnetron sputtering.

[0063] This embodiment is particularly preferred when the first material is not aluminum oxide AI2O3.

[0064] Indeed, magnetron sputtering is particularly suitable for the deposition of binary compounds, and in particular nitrides or carbides.

[0065] Furthermore, when the method comprises a step of depositing a second material, it is preferably carried out by magnetron sputtering.

[0066] This embodiment is in fact particularly effective for depositing layers of the first and, where appropriate, the second material, in thicknesses as thin as desired.

[0067] In addition, the magnetron sputtering method provides a unique deposition method, carried out in a single chamber. It is sufficient to change the target or add an additional target in the magnetron sputtering chamber, without having to modify the position of the substrate to be able to deposit the second layer.

[0068] In one embodiment, the method may further comprise, before the step of depositing the first layer, a degreasing step.

[0069] In one embodiment, the degreasing step may be carried out in two stages: pre-degreasing, by exposure to organic solvents, followed by alkaline degreasing.

[0070] This step aims to ensure good cleanliness of the substrate and thus prevent impurities from harming the good deposition of the first layer, or harming the excellent adhesion that can be expected from it.

[0071] In one embodiment, the method may further comprise, before the step of depositing the first layer, and where appropriate before or after the degreasing step, a sandblasting step.

[0072] In one embodiment, the sandblasting step may be mechanical or chemical.

[0073] Such a sandblasting step aims to ensure a uniform surface roughness.

[0074] In one embodiment, the substrate for carrying out a method which has just been described may be a turbomachine blade whose leading edge has been coated and then damaged, for example during operation.

[0075] In other words, it is possible to apply the method of the invention to repair a blade without requiring removal of the pre-existing coating.

[0076] In fact, it is possible to determine the thickness of the remaining coating by a known non-destructive method, and to deposit a coating by the described method at the locations where it is necessary. Brief description of the drawings

[0077] [Fig. 1] Figure 1 shows an enclosure for carrying out a method in one embodiment.

[0078] [Fig. 2] Figure 2 shows a blade in one embodiment.

[0079] [Fig. 3] Figure 3 shows a blade in the same embodiment as that of Figure 2 but in another view. Description of the embodiments

[0080] The invention is now described by means of figures, present for descriptive purposes to illustrate certain embodiments of the invention and which should not be interpreted as limiting the latter.

[0081] PVD deposition can be done at room temperature on a metal foil already attached to a fan blade.

[0082] This ensures that the organic matrix composite material is not damaged.

[0083] In an embodiment where the deposition is made on the metal foil before assembly of said foil with the organic matrix composite material, the process is preferably carried out at a temperature less than or equal to 300°C. This ensures excellent integrity of the metal foil, in particular by avoiding any phase transformation of the foil.

[0084] Figure 1 schematically represents a device for carrying out deposition by magnetron sputtering according to one embodiment of the invention.

[0085] The device comprises a chamber 10 intended to receive a plasma gas, for example consisting of a mixture of argon and nitrogen. The device further comprises a source of plasma gas (not shown) in communication with the chamber 10.

[0086] In a chamber 10, a gas is introduced through the inlet 6 and a plasma is generated between the target 11 and the substrate 12 to be coated. Under the effect of an electric field, obtained by imposing a voltage between the target 11 and the substrate 12, electrons are generated by the target and can ionize by collision the atoms constituting the plasma.

[0087] The presence of a magnetic field generated by a magnet 104 disposed near the target 11 confines the generated electrons near the target and increases the probability that the collision between an electron and an atom of the plasma takes place there.

[0088] When such a collision takes place, a high-energy species is generated, and the latter can bombard the target 11 and tear off, by elastic impact, particles from the target 11. The particles of the target 11 thus torn off can then be deposited on the substrate 12 to form the deposit.

[0089] The metal of target 11 corresponds to the metal that will be deposited.

[0090] In one embodiment, the target 11 comprises a pure metal, for example greater than 99% atomic pure, and preferably greater than 99.9% atomic pure.

[0091] During coating, the target 11 is polarized. The polarization of the target 11 is imposed by a power supply assembly not shown.

[0092] In chamber 10, applying a voltage between target 11 and substrate 12 in the presence of an atmosphere comprising nitrogen creates a plasma. Electrons are generated by target 11 and can ionize the atoms constituting the plasma by collision.

[0093] The coating can be carried out under vacuum, for example at a pressure in the chamber 10 less than or equal to 2 Pa, for example between 0.5 Pa and 2 Pa.

[0094] The substrate may be heated during coating by a heater not shown. Alternatively, the substrate may not be heated during coating.

[0095] The substrate temperature may for example be greater than or equal to 20°C during coating, for example between 20°C and 600°C, or even between 30°C and 500°C.

[0096] The temperature allows thermal energy to be brought to the substrate, and thus allows a certain mobility of the atoms favoring the recombination of the atoms deposited on the surface of the substrate.

[0097] In particular, magnetron sputtering makes it possible to obtain a coating on the leading edge, which has the desired strength properties while representing only a small additional weight.

[0098] In this respect, the coatings described are more advantageous than the metallic foils proposed in the prior art.

[0099] Figure 2 shows a blade according to the invention, for example a fan blade.

[0100] Such a blade comprises a blade body 110, which extends in the longitudinal direction D between an inner end 110b and an outer end 110a, and in an axial direction D Abetween a leading edge 111, not visible in figure 1 because covered by the coating 200, and a trailing edge 112.

[0101] The exact profile of the blade is not limiting. As described, however, the blade body 110 is made of an organic matrix composite material, and the coating 200 satisfies the described compositions.

[0102] Figure 2 further illustrates the intrados 113 and the extrados 114 according to the usual meanings of these terms in the field of aeronautical blades.

[0103] As illustrated in Figure 2, the coating 200 may cover the entire leading edge 111, from the inner end 110b to the outer end 110a.

[0104] Figure 3 is a top view of a blade according to Figure 2.

[0105] Figure 3 is a blade 100 whose leading edge 111 is coated with a metal foil 131.

[0106] The metal foil protecting the leading edge is itself coated with a protective layer 200, which here covers the entire leading edge 111.

[0107] Figure 3 illustrates the thickness ei of the coating 200, which may be between 5.0 pm and 10 pm.

[0108] This view illustrates an embodiment in which the covering 200 not only covers the leading edge 111 but also extends over the intrados 113 and the extrados 114.

[0109] The length characterizes the distance over which the coating covers the intrados and the length l e the distance over which the coating covers the extrados.

[0110] As described, the portion of the intrados and / or extrados covered by the coating is not more than 5.0 mm from the leading edge.

[0111] Although the coating 200 only has a single layer in Figure 3, this choice is made for simplicity, and it should in no way be considered limiting.

[0112] Samples were taken to confirm that the proposed coatings could actually be obtained and to study their properties.

[0113] For this, coatings were obtained by a physical vapor deposition method.

[0114] Targets of tantalum, chromium, aluminum and tungsten have been proposed.

[0115] To obtain a carbide or a nitride, the physical vapor deposition chamber can be supplied with nitrogen and / or methane.

[0116] Additionally, argon can be used as a neutral carrier gas.

[0117] For example, the argon flow rate may be 92 sccm, the nitrogen flow rate may be 3.2 sccm when a nitride is desired, and the methane flow rate may be 3.0 sccm when a carbide is desired.

[0118] The deposition is carried out at a temperature between 25°C and 300°C.

[0119] A bias voltage is applied to the substrate which can be between -300 V and -900 V.

[0120] Similarly, a power is applied to the target, which can be between 500 and 1500 W.

[0121] The parameters described allow a coating of 5.0 nm to be obtained.

[0122] The examples allowed the following trends to be identified: - the enrichment of tungsten carbide films enriched with carbon, for example, whose quantity of carbon has been multiplied by between 3 or 4 leads to an increase in their adhesion, increases their hardness and reduces their coefficient of friction by 50% and improves their resistance to wear; - the addition of aluminum in a layer of chromium nitride and aluminum CrAIN, improves wear resistance and acts as a thermal barrier; - the addition of aluminum in the layer of aluminum nitride and titanium TiAIN, improves the wear resistance and thermal stability of the coating.

Claims

Claims

1. Blade (100) made of organic matrix composite material comprising a blade body (110) extending in a longitudinal direction (D L ) between an inner end (110b) and an outer end (110a) and in an axial direction (D A ) between a leading edge (111) and a trailing edge (112), at least a portion of the leading edge of the blade being covered with a metal foil (131), the blade being characterized in that at least a portion of the metal foil (131) is coated with at least: - a first layer comprising a first material, the first material being aluminum oxide, a metal carbide or a metal nitride, the first layer being disposed directly on the leading edge of the blade body; and - in the case where the first material is not aluminum oxide, a second layer comprising a second material, the second material comprising a metal nitride, a metal carbide, a metal carbonitride or a metal silicide different from the first material, the second layer being arranged directly on the first layer.

2. The blade (100) of claim 1, wherein the first material is aluminum oxide AI2O3.

3. The blade (100) of claim 1, wherein the first material is selected from titanium nitride TiN, chromium nitride CrN, and tungsten carbide WC.

4. Blade (100) according to claim 3, wherein the second material is selected from aluminum titanium nitride TiAIN, aluminum chromium nitride CrAIN, aluminum titanium carbonitride TiAICN, aluminum chromium carbonitride CrAICN, aluminum titanium silicide TiAISi, carbon-enriched tungsten carbide WCC.

5. A blade (100) according to one of claims 1 to 4, wherein the coating is present on the metal foil of the leading edge (111) from the inner end (110a) to the outer end (110b).

6. Blade (100) according to one of claims 1 to 5, in which the coating comprises a thickness less than or equal to 200 μm.

7. A blade (100) according to one of claims 1 to 6, wherein the blade is a fan blade or a propeller blade.

8. A method of manufacturing a blade according to one of claims 1 to 7 comprising at least the following steps: - a step of depositing a first material directly on the metal foil of a blade made of organic matrix composite material, at least part of the leading edge of which is intended to be covered by a metal foil, the first material being aluminum oxide, a metal carbide or a metal nitride; and - in the case where the first material is not aluminum oxide, a step of depositing a second layer of a second material on a portion coated by the first layer, the second material comprising a metal nitride, a metal carbide, a metal carbonitride or a metal silicide different from the first material; - bonding the metal foil to the leading edge of a blade made of organic matrix composite material.

9. Manufacturing method according to claim 8, wherein the deposition of the first material and / or the second material is carried out by magnetron sputtering.

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