Protective coating for turbomachine blades.

Abstract

Protective coating for turbomachine blade. The invention relates to a blade (100) made of an organic matrix composite material, at least a portion of whose leading edge (111) is covered with a metallic shim (131). The blade is characterized in that at least a portion of the metallic shim 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 disposed directly on the first layer. Figure for the abstract: Fig. 1.

Description

Title of the invention: Protective coating for turbine blade. technical field

[0001] The present description relates to a protective coating for a turbomachine blade made of composite material. Previous technique

[0002] Polymer matrix composite materials, also called organic matrix composites, are known for the production of cold part elements of aeronautical turbomachinery, such as fan blades. These materials generally have a lower weight than metallic alloys for the same performance, giving them an industrial advantage for applications where weight issues are critical.

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

[0004] The blower blades must comply with important regulations, and must in particular resist erosion and any impacts caused by elements external to the engine.

[0005]

[0006] For this purpose, it has been proposed in the prior art to glue metallic shims onto 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 metallic flakes 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 blower blades and their metallic shims. Description of the invention

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

[0010] To this end, it proposes, according to a first aspect, a blade made of material an organic matrix composite comprising a blade body extending in a longitudinal direction between an inner end and an outer end and in an axial direction between a leading edge and a trailing edge, at least a portion of the blade's leading edge being covered with metallic slush, the blade being ca characterized in that at least part of the metallic tinsel 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 disposed directly on the leading edge of the blade body; and - in the case where 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 different from the first material, the second layer being disposed directly on the first layer.

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

[0012] Erosion resistance can be evaluated by a method called three-dimensional measurement, also known as "TDM" for the English acronym "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 evaluated by the TDM technique applied to measurements obtained on a blade after an impact.

[0014] In one embodiment, the first material is aluminum oxide A12O3.

[0015] In one embodiment, the protective coating disposed on the metal foil tallique comprises only one layer, i.e. a first layer, and this comprises aluminium oxide A12O3 as the first material.

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

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

[0018] In one embodiment, the protective coating disposed on the metallic shim 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, metal carbide, metal carbonitride or metal silicide different from the first material, the second layer being disposed directly on the first layer.

[0019] Such an embodiment makes it possible to ensure excellent protection of the leading edge.

[0020] The first material is chosen to exhibit excellent adhesion with the metallic material shim but is also a transition material to allow the adhesion of the second material.

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

[0022] In one embodiment, the first layer can contain 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 chosen from tungsten W, titanium Ti or chromium Cr.

[0024] In one embodiment, the first material is a binary compound, that is to say, it is composed only of a metal and another element chosen from carbon or nitrogen.

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

[0026] In one embodiment, the second layer can contain 60 to 80% by mass 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 chosen 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 metallic carbonitride and is furthermore a quaternary compound, that is to say, it is composed of four elements, one being a metal, another being carbon, and a third being nitrogen.

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

[0031] In one embodiment, the second material comprises a metal nitride, a metal carbide, a metal carbonitride, of which 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 / TiAlCN, CrN / CrAlCN, TiC / TiCAlN.

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

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

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

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

[0037] Alternatively, the coating may cover only a portion of the metallic slenderness of the leading edge.

[0038] Indeed, the inventors have observed that the metallic shim of the leading edge shows greater wear the closer one is to the outer end of the blade.

[0039] Also, in one embodiment the metallic slender 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 disposed only on X% of the length of the metallic slender of the leading edge starting from the upper end.

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

[0042] In one embodiment, the blade made of composite material can be a blower 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 metallic slush.

[0044] In one embodiment, the coating can cover, in addition to the leading edge, a portion of the extrados and / or the intrados.

[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 metallic slender itself covers, in addition to the leading edge, a portion of the extrados and / or the intrados, and the coating is thus entirely disposed on the metallic slender.

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

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

[0049] According to another aspect of it, the invention relates to a method for manufacturing a blade as described above, the method comprising at least the following steps: - a step of depositing a first material directly onto the metallic shim of a blade made of organic matrix composite material, at least a portion of whose leading edge is intended to be covered by metallic shim, the first material being aluminum oxide, a metal carbide, or a metal nitride; and - in the case where the first material is not aluminium 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; - the bonding of the metallic shim to the leading edge of a blade made of organic matrix composite material.

[0050] The inventors propose by this process a solution for obtaining a blade with the advantages already described above for the blade as such.

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

[0052] In one embodiment, the step of bonding the metallic shim 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 a blade to be close to the final part as soon as the coating step is completed.

[0054] Alternatively, the step of bonding the metallic shim to the leading edge of the blade in organic matrix composite material can be carried out after the step of deposition of the first material, and where appropriate after the step of deposition of the second material.

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

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

[0057] In a particular embodiment, where the first material is aluminum oxide A12O3, the deposition can be carried out by sol-gel deposition, by laser deposition or by thermal spraying.

[0058] Indeed, these methods are particularly suited to the deposition of aluminium oxide and allow in particular the selection of the deposition process best suited to the desired thickness for the coating.

[0059] In particular, a sol-gel deposition method can be chosen for a coating with a thickness between 5.0 pm and 10 pm and a thermal spraying process 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 applicable, the second layer can be carried out by a physical vapor phase deposition process.

[0061] In one embodiment, the physical vapor phase deposition process can be magnetron sputtering.

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

[0063] This embodiment is particularly preferred when the first material is not aluminium oxide A12O3.

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

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

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

[0067] Furthermore, 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 within the magnetron sputtering chamber, without having to modify the substrate position, to deposit the second layer.

[0068] In one embodiment, the process may further include, before the first layer deposition step, a degreasing step.

[0069] In one embodiment, the degreasing step can be carried out in two steps: 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 proper deposition of the first layer, or from harming the excellent adhesion that can be expected from it.

[0071] In one embodiment, the process may further include, before the first layer deposition step, 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 homogeneous surface roughness.

[0074] In one embodiment, the substrate for carrying out a process which has just been described can 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 the removal of the pre-existing coating.

[0076] Indeed, it is possible to determine the thickness of the remaining coating by a known non-destructive method, and to deposit a coating by the method described in the places where it is needed. Brief description of the drawings

[0077] [Fig. 1] The [Fig. 1] represents an enclosure for carrying out a process in an embodiment.

[0078] [Fig.2] Fig.2 represents a blade in one embodiment.

[0079] [Fig.3] Fig.3 represents a blade in the same embodiment as that of the [Fig.2] but in a different view. Description of the implementation methods

[0080] The invention is now described by means of figures, which are 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 carried out at room temperature on a metallic foil already attached to a blower blade.

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

[0083] In an embodiment where the deposition is made on the metallic foil before as When assembling said shim with the organic matrix composite material, the process is preferably carried out at a temperature of 300°C or less. This ensures excellent integrity of the metallic shim, notably by preventing any phase transformation of the shim.

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

[0085] The device includes a chamber 10 for receiving a plasma-forming gas, for example, a mixture of argon and nitrogen. The device further includes a plasma-forming gas source (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 applying a voltage between the target 11 and the substrate 12, electrons are generated by the target and can ionize the constituent atoms of the plasma by collision.

[0087] The presence of a magnetic field generated by a magnet 104 placed 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 will take place there.

[0088] When such a collision takes place, a high-energy species is generated, and this can bombard the target 11 and tear away, by elastic collision, particles from the target 11. The particles from the target 11 thus torn away 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 pure at with a ratio of more than 99% in atomic percentages, and preferably with a ratio of more than 99.9% in atomic percentages.

[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 a nitrogen-containing atmosphere creates a plasma. Electrons are generated by target 11 and can ionize the constituent atoms of the plasma by collision.

[0093] The coating can be carried out under vacuum, for example at a pressure in 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 heating element (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] Temperature allows thermal energy to be supplied to the substrate, and thus allows a certain mobility of atoms promoting the recombination of 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 resistance properties while representing only a small additional weight.

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

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

[0100] Such a blade comprises a blade body 110, which extends in the longitudinal direction tudinal Dl between an inner end 110b and an outer end 110a, and in an axial direction DA between a leading edge 111, not visible on the [Fig.l] because covered by the coating 200, and a trailing edge 112.

[0101] The exact profile of the blade is not limiting. However, as described, the blade body 110 is made of organic matrix composite material, and the coating 200 meets the compositions described.

[0102] Fig. 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 [Fig. 2], the coating 200 can cover the entire leading edge 111, from the inner end 110b to the outer end 110a

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

[0105] The [Fig.3] is a blade 100 whose leading edge 111 is covered with a metal foil tallique 131.

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

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

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

[0109] The length h characterizes the distance over which the coating covers the intrados and the length le characterizes 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 away from the leading edge.

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

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

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

[0114] Tantalum, chromium, aluminum and tungsten targets have been proposed.

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

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

[0117] For example, the argon flow rate can be 92 sccm, the nitrogen flow rate can be 3.2 sccm when a nitride is desired, and the methane flow rate can 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 make it possible to obtain a coating of 5.0 nm.

[0122] The examples helped to identify the following trends: - the enrichment of carbon-enriched tungsten carbide films, for example, where the amount 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 wear resistance; - the addition of aluminium in a layer of chromium and aluminium nitride CrAIN, improves wear resistance and acts as a thermal barrier; - The addition of aluminum in the aluminum and titanium nitride layer TiAIN improves the wear resistance and thermal stability of the coating.

Claims

Demands

1. Blade (100) of organic matrix composite material comprising a blade body (110) extending in a longitudinal direction (DL) between an inner end (110b) and an outer end (110a) and in an axial direction (DA) 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 metallic shim (131), the blade being characterized in that at least a portion of the metallic shim (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 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 different from the first material, the second layer being disposed directly on the first layer.;

2. Blade (100) according to claim 1, wherein the first material is aluminum oxide A12O3.

3. Blade (100) according to 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 TiAlCN, aluminum chromium carbonitride CrAlCN, aluminum titanium silicide TiAISi, carbon-enriched tungsten carbide WCC.

5. Blade (100) according to any one of claims 1 to 4, wherein the coating is present on the metallic slender of the leading edge (111) from the inner end (110a) to the outer end (110b).

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

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

8. A method for manufacturing a blade according to any one of claims 1 to 7 comprising at least the following steps: - a step of depositing a first material directly onto the metal shim of a blade made of an organic matrix composite material, at least a portion of whose leading edge is intended to be covered by a metal shim, 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 onto 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; - the bonding of the metal shim to the leading edge of a blade made of an organic matrix composite material.

9. A 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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