Method of depositing an abrasive coating on the tip of an aircraft turbine blade

Abstract

The present invention relates to a method for depositing an abrasive coating on the tip (1) of an aircraft turbine blade, the tip being made of metal or ceramic. The method includes: - positioning a sintering mold on the tip (1), - covering the surface (2) of the tip (1) defined by the sintering mold with an abrasive outer layer (5) comprising a metal-based or ceramic-based matrix (6) and abrasive grains (7), and - performing high-temperature flash firing on the abrasive outer layer (5) to form the tip (1) covered with the abrasive coating.

Description

Technical Field

[0001] This invention relates to the general field of aeronautics, and more particularly to a method for depositing an abrasive coating on the tip of a turbine blade of a high-pressure turbine of an aircraft turbine. Background Technology

[0002] It is known that abrasive grains embedded in a matrix are placed at the tip of a high-pressure turbine blade of an aero-engine.

[0003] In turbines where the rotor and stator are in contact, the blade tips impact the surface of a ring made of a material designed to be sacrificed because this material is softer than the abrasive grains. In this way, a significantly reduced space is created between the blade tip and the ring through the grinding action of the abrasive grains on the ring, thus minimizing gas losses. The recirculated gas velocity at the blade tip and the radial clearance between the stationary and moving parts forming the labyrinth are also reduced.

[0004] This allows for improved efficiency of the turbine's compressor or high-pressure turbine and reduced fuel consumption. For example, reducing the clearance between the blade tip and the ring by 25 µm results in an estimated 0.1% reduction in fuel consumption.

[0005] A type of abrasive coating is known from document US005702574A, which is based on non-oxide c-BN particles contained in an MCrAlY (M=Ni / Co) matrix, with a thickness between 125µm and 150µm, and is applied by electrodeposition to the blade tips of a compressor stage or high-pressure stage of a turbine mainly composed of nickel and cobalt.

[0006] This abrasive coating exhibits the desired grinding performance, but the non-oxide particle-based (c-BN) abrasive material used gradually sublimates at the desired operating temperature (above 900°C). Therefore, the oxidation resistance (900°C) of this abrasive coating is limited, and its grinding (or cutting) effectiveness will be restricted during its temperature aging.

[0007] Other methods for creating abrasive coatings on blade tips are also known, such as deposition methods using explosive spraying of a matrix.

[0008] However, no existing technology allows for the provision of an abrasive coating on the blade tip that has excellent high-temperature oxidation resistance and thus maintains grinding effectiveness over time. Summary of the Invention

[0009] The purpose of this invention is to provide a high-pressure turbine blade for a turbine, comprising a blade tip covered with an abrasive coating that has excellent high-temperature oxidation resistance and time-constant grinding effectiveness.

[0010] This invention relates to a method for depositing an abrasive coating on the tip of an aircraft turbine blade. The blade tip is made of metal or ceramic.

[0011] Deposition methods include: - The step of positioning the sintering mold on the tip of the blade; - The step of covering the surface of the blade tip defined by a sintering mold with an abrasive outer layer comprising a metal-based or ceramic-based matrix and abrasive grains; and - A step of performing flash burning on the outer layer of abrasive to form the blade tip covered by an abrasive coating.

[0012] The present invention provides a high-pressure turbine blade for a turbine, comprising a blade tip covered with an abrasive coating that exhibits excellent high-temperature oxidation resistance and time-constant grinding effectiveness.

[0013] This invention allows for improved durability of high-pressure turbine blade tips, improved and long-term maintenance of high-pressure turbine efficiency, while maintaining a reduced gap between the abrasive coating deposited on the blade tips and the wearable coating deposited on the turbine rings.

[0014] The matrix of the abrasive coating has high-temperature structural stability relative to the chemical composition of the abrasive grains.

[0015] As a variation, an abrasive outer layer is obtained by first depositing a metal-based or ceramic-based powder layer to form a matrix in the form of a powder layer, and then depositing an abrasive powder layer a second time on the matrix.

[0016] This method allows for the simple acquisition of abrasive coatings containing abrasive particles on a substrate surface.

[0017] As a variation, a metal-based or ceramic-based powder layer encapsulating a polymer adhesive matrix is ​​first deposited using a fused wire deposition method to form a matrix in the form of encapsulated powder, and an abrasive outer layer is obtained by second-depositing an abrasive layer encapsulated in the polymer adhesive matrix onto the matrix using a fused wire deposition method.

[0018] This method also allows for the preparation of abrasive coatings containing abrasive particles on the substrate surface.

[0019] The manufacturing method of deposited fuses helps to reduce the environmental impact associated with component repair by allowing damaged or worn parts to be repaired by locally adding material, thus avoiding the scrapping of these parts.

[0020] As a variation, the first deposition is performed by printing a metal or ceramic substrate to form the printing matrix, and the abrasive outer layer is obtained by printing abrasive particles onto the printing matrix for a second deposition.

[0021] This method also allows for the preparation of abrasive coatings containing abrasive particles on the substrate surface.

[0022] As a variation, an abrasive outer layer is obtained by mixing abrasive powder with a matrix of metal-based or ceramic-based powder.

[0023] This method allows for the preparation of abrasive coatings containing abrasive inclusions in both the volume and on the surface (i.e., within and on the surface of the matrix).

[0024] As a variation, the abrasive outer layer is deposited directly onto the surface of the blade tip, or onto a metal-based or ceramic-based connector layer previously deposited on the surface of the blade tip, or onto a metal-based or ceramic-based intermediate layer deposited between the connector layer and the abrasive outer layer.

[0025] As a variation, the manufacturing method includes, prior to the step of covering the blade tip surface with an abrasive outer layer, the following steps: depositing the abrasive outer layer into a preforming mold; performing a flash firing on the abrasive outer layer to form a preformed abrasive outer layer; and depositing the preformed abrasive outer layer into a sintering mold. The flash firing step is performed on the preformed abrasive outer layer.

[0026] As a variant, the ratio between the median diameter of the abrasive grain and the matrix thickness is between 0.6 and 0.9. The thickness of the outer layer of the abrasive is between 3 µm and 400 µm.

[0027] As a variant, the ratio between the median diameter of the matrix particles and the median diameter of the abrasive particles is between 0.002 and 0.4.

[0028] As a variation, when the matrix is ​​metallic and the blade tip surface is nickel-based, the oven temperature for the flash firing step is between 700°C and 1000°C, preferably between 800°C and 900°C. The pressure inside the oven is between 25 MPa and 125 MPa, preferably between 50 MPa and 100 MPa. The cycle time is between 1 minute and 60 minutes, preferably between 5 minutes and 10 minutes. The oven temperature corresponds to the temperature experienced by the blade tip. Similarly, the pressure inside the oven corresponds to the pressure applied to the blade tip.

[0029] As a variation, when the substrate is a ceramic substrate and the blade tip surface is nickel-based, the oven temperature for performing the flash firing step is between 900°C and 1300°C, preferably between 1000°C and 1100°C. The cycle time is between 1 minute and 60 minutes, preferably between 5 minutes and 10 minutes.

[0030] As a variation, when the substrate and blade tips are made of ceramic, the oven temperature for the flash firing step is between 900°C and 1500°C, preferably between 1200°C and 1400°C. The pressure inside the oven is between 25 MPa and 150 MPa, preferably between 50 MPa and 100 MPa. The cycle time is between 1 minute and 60 minutes, preferably between 5 minutes and 10 minutes.

[0031] The present invention also relates to an aircraft turbine blade comprising at least one blade tip containing an abrasive coating obtained by the manufacturing method as defined above. Attached Figure Description

[0032] The invention and its advantages will be better understood by reading the following detailed description of various embodiments of the invention given by way of non-limiting examples. This description refers to the accompanying drawings, in which: [ Figure 1 ] Figure 1 The illustration schematically shows the tip surface of a blade covered with an abrasive coating according to an embodiment of the present invention; [ Figure 2 ] Figure 2 The illustration schematically shows the blade tip surface covered with an abrasive coating according to another embodiment of the present invention; [ Figure 3 ] Figure 3 The illustration schematically shows the blade tip surface covered with an abrasive coating according to another embodiment. Detailed Implementation

[0033] The high-pressure turbine blade of an aero-engine, made of metal or ceramic, includes a blade tip 1 covered with an abrasive coating comprising abrasive grains 7 embedded in a metal-based or ceramic-based matrix 6.

[0034] When contact occurs between the rotor and stator in the turbine, the blade tip 1 impacts the surface of a ring made of a material designed to be sacrificed because it is softer than the abrasive grains 7. In this way, a significantly reduced space is created between the tip and the ring by the grinding action of the abrasive grains on the ring, thereby minimizing gas losses.

[0035] The present invention relates to a method for depositing an abrasive coating on the tip 1 of a high-pressure turbine blade.

[0036] In general, this deposition method includes: - The step of positioning the sintering mold on the blade tip 1. - The step of covering the surface 2 of the blade tip 1 defined by the sintering mold with an abrasive outer layer 5 formed of a metal-based or ceramic-based matrix 6 containing abrasive grains 7, and - The step of sintering the outer abrasive layer 5 to form the blade tip 1 covered by the abrasive coating.

[0037] Preferably, the deposition method is performed on the tips 1 of all blades.

[0038] Preferably, the sintering step is a flash firing step performed at a high temperature (greater than 900°C).

[0039] Flash sintering, also known as ultrafast sintering or SPS (spark plasma sintering), or FAST (field-assisted sintering), is a powder metallurgy method. This technology is related to HP (hot pressing), but differs in the means of heating the tool containing the material to be sintered. In SPS sintering, pulsed direct current with waveforms varying depending on the manufacturer is applied via electrodes to the tool (mold + indenter) containing the material to be densified. A series of high-intensity current pulses are applied. This allows the material to be heated via the Joule effect, with a temperature rise rate reaching hundreds of degrees Celsius per minute. The applied pressure (up to hundreds of megapascals in the case of a hydraulic press on the indenter) and ultrafast heating thus allow for lower sintering temperatures (compared to conventional sintering techniques), limiting reactions / diffusion at the material interfaces and controlling the material's microstructure. In most cases, the tool used is made of graphite, and sintering is performed under an inert atmosphere or vacuum.

[0040] The surface 2 of the blade tip 1 forms a substrate. If the substrate 6 of the blade tip 1 and the abrasive outer layer 5 is made of metal, the abrasive outer layer 5 can be directly deposited onto the blade tip 1.

[0041] The solution involves forming a multi-layered and functionalized coating in a single step using a flash burning method. This coating exhibits grinding properties, structural stability under high-temperature cyclic oxidation conditions, and high durability due to the inclusion of abrasive grains on its surface or in its volume. The coating is formed on the tip of a high-pressure turbine blade composed of a high-temperature alloy.

[0042] As a variation, the deposition method may include an initial step of depositing a metal-based or ceramic-based connecting sublayer 4 on the surface 2 of the blade tip 1, regardless of whether the blade tip 1 is made of metal or ceramic.

[0043] The connecting sublayer 4 is located between the surface 2 of the blade tip 1 and the abrasive outer layer 5. Flash burning is performed on the entire blade, and therefore on the connecting sublayer 4 and the abrasive outer layer 5.

[0044] If the connecting sublayer 4 is metal, then the matrix 6 of the abrasive outer layer 5 can be metal or ceramic.

[0045] If the connecting sublayer 4 is made of ceramic, then the matrix 6 of the abrasive outer layer 5 can also be made of ceramic.

[0046] The connecting sublayer 4, also known as the bonding sublayer, can be deposited on the surface 2 of the blade tip 1 by thermal spraying, physical vapor deposition, vapor phase aluminizing, flash burning, slurry deposition followed by consolidation heat treatment, or any other compatible deposition method.

[0047] The thickness of the connecting sublayer 4 is between 1µm and 200µm, preferably between 25µm and 150µm.

[0048] The connecting sublayer 4 allows the upper layer to bond well to the surface 2 of the blade tip 1.

[0049] As a variation, the deposition method includes at least one step of depositing a ceramic intermediate layer 3 between the connector sublayer 4 and the abrasive outer layer 5. The intermediate layer 3 is deposited onto the connector sublayer 4.

[0050] Intermediate layer 3 also allows for good lifetime performance under cyclic oxidation and thermal shock conditions.

[0051] The intermediate layer 3 can be deposited by thermal spraying, physical vapor deposition, vapor phase aluminizing, flash burning, slurry deposition followed by consolidation heat treatment, or any other compatible deposition method.

[0052] The thickness of the intermediate layer 3 is between 1µm and 250µm, preferably between 50µm and 150µm.

[0053] Abrasive grain 7 contains oxides selected from the following: α-Al₂O₃, ZrO₂ – 4.5 mol% ≤ RE₂O₃, where RE = Sc, Y, La, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Tb; Y₂O₃-ZrO₂-Ta₂O₅, Y₂O₃-ZrO₂-Nb₂O₅, ZrO₂-Al₂O₃, MgAl₂O₄ and HfO₂ – 4.5 mol% ≤ RE₂O₃, where RE = Sc, Y, La, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Tb.

[0054] As a variant, the abrasive grain 7 contains a non-oxide compound or a mixture of oxide and non-oxide components selected from SiC, Si3N4, ZrC, and B4C.

[0055] The abrasive grains 7 have a needle-like (angular and angular) shape or form.

[0056] According to one embodiment, the matrix 6 and the abrasive particles 7 are deposited in powder form before flash burning.

[0057] A first deposition of powder containing a metal-based or ceramic-based compound is performed to form a matrix 6 in the form of a powder bed or powder layer, and a second deposition of abrasive powder 7 is performed on the powder layer forming the matrix 6.

[0058] According to one embodiment, the abrasive outer layer 5 in powder form is directly deposited into a sintering mold, onto the surface 2 of the blade tip 1 defined by the sintering mold. The sintering mold has dimensions and geometry adapted to the turbine blade tip to be functionalized. The turbine blade is fixed in the sintering mold.

[0059] The powder bed or powder layer is deposited sequentially and uniformly in the sintering mold by means of gravity deposition of particles, for example, manually or automatically, using a screen.

[0060] Abrasive particles 7 are deposited on the surface of matrix 6 in the form of a fine oxide layer with a thickness strictly less than 2µm to maintain chemical and structural stability with matrix 6 during temperature aging.

[0061] Inclusions of abrasive grains 7 on the outer layer 5 of the abrasive are obtained.

[0062] The median diameter of the abrasive grains 7 is between 0.1µm and 400µm, preferably between 0.1µm and 250µm.

[0063] Regardless of the nature (ceramic or metallic) of the matrix 6 of the abrasive outer layer 5, the powder used must have a fine and narrow particle size distribution to promote the embedding and adhesion of the abrasive particles 7 on the surface and in the volume.

[0064] The median diameter of the particles in matrix 6 (ceramic or metal) is between 0.1 µm and 20 µm, preferably between 0.5 µm and 10 µm.

[0065] The median diameter of the matrix particles must be selected between 0.002 and 0.4, considering the ratio between the median diameter of the matrix particles and the median diameter of the abrasive particles.

[0066] This allows for improved embedding and adhesion of the abrasive particles 7 within the matrix 6. Using fine, angular particles further enhances embedding and adhesion.

[0067] The thickness of the matrix 6 containing the inclusions of the abrasive grains 7 is selected based on the size of the abrasive grains 7 used, or more precisely, based on the median diameter of the abrasive grains 7.

[0068] Regarding the selection of the thickness of matrix 6, the ratio between the median diameter of abrasive grain 7 and the thickness of matrix 6 must be between 0.6 and 0.9.

[0069] The thickness of the outer abrasive layer 5 is between 3µm and 400µm.

[0070] This allows the thickness of the matrix 6 to be adjusted according to the median diameter of the abrasive grains 7, so as to obtain good durability of the abrasive coating while maintaining good grinding performance.

[0071] According to one embodiment, a matrix 6 in the form of an encapsulated powder layer is formed by first depositing a metal-based or ceramic-based powder layer encapsulated in a polymer adhesive matrix by a fused wire deposition method, and an abrasive outer layer 5 is obtained by second depositing an abrasive 7 layer encapsulated in a polymer adhesive matrix onto the matrix 6 in the form of an encapsulated powder layer by a fused wire deposition method.

[0072] The powder is dispersed and encapsulated in a polymer binder matrix, which decomposes during heat treatment and flash burning, thereby releasing the encapsulated particles. This method allows for better control over the thickness of the deposited material.

[0073] According to another embodiment, the abrasive outer layer 5 is obtained by a first deposition of a metal-based or ceramic-based layer and a second deposition of abrasive particles 7 onto the metal-based or ceramic-based layer.

[0074] After being solidified by flash burning, the surface coverage of the abrasive grains 7 is greater than or equal to 70% of the surface area of ​​the outer abrasive layer 5, greater than or equal to 80% of the surface area of ​​the outer abrasive layer 5, greater than or equal to 90% of the surface area of ​​the outer abrasive layer 5, or even more preferably 100%.

[0075] The surface densification of the outer abrasive layer 5 is greater than 95%, preferably greater than 98%.

[0076] According to another embodiment, an abrasive outer layer 5 is obtained by mixing powder containing a metal-based or ceramic-based compound intended to form matrix 6 with powder of abrasive grains 7 to obtain inclusions of abrasive grains 7 in a volume (i.e., inside and on the surface of matrix 6).

[0077] Powder mixing can be achieved using a three-dimensional mixer, such as a Turbula® brand mixer.

[0078] The mass loading rate of abrasive particles 7 in the matrix 6 is between 20% and 90% of the total mass, and preferably between 30% and 70% of the total mass.

[0079] The powder mixture is uniformly deposited into the sintering mold by gravity deposition of particles, for example, manually or automatically, using a sieve.

[0080] As a variation, the powder mixture is dispersed and encapsulated in a polymer binder matrix, and then deposited into a sintering mold by a fused wire method, or directly deposited on the surface 2 of the blade tip 1 or on the connector layer 4.

[0081] The polymer binder matrix of the abrasive outer layer 5 decomposes during the heat treatment process during flash burning, thereby releasing the encapsulated particles.

[0082] According to another embodiment, the abrasive outer layer 5 is obtained by directly printing and depositing a mixture of metal-based or ceramic-based powder and abrasive powder 7 onto the surface 2 of the blade tip 1 or onto the connecting sublayer 4.

[0083] After being solidified by flash firing, the surface coverage of the abrasive grains 7 is greater than or equal to 70% of the outer abrasive layer 5.

[0084] The densification of the layer containing abrasive inclusions is greater than 95%, preferably greater than 98%.

[0085] When the metal matrix 6 has particulate inclusions 7, a surface finishing process can be applied by mechanical action (sandblasting) or by chemical etching (solvent etching) to make abrasive particles 7 appear on the surface.

[0086] According to one embodiment, the blade tip is made of metal and consists of a high-temperature alloy, for example, selected from Ni-based or Co-based high-temperature alloys. The blade tip may, for example, consist of a low-sulfur AM1 high-temperature alloy, MC-GN, CMSX4 and its derivatives, or René and its derivatives.

[0087] As described below, one or more intermediate layers 3 can be deposited onto the connecting sublayer 4.

[0088] As a variation, the intermediate layer 3 and the connecting sublayer 4 can be deposited in powder form. Preferably, a sintering step is performed on each layer.

[0089] The n intermediate layers 3 can have the same chemical composition as the connecting sublayers 4.

[0090] One or more intermediate layers 3 and connecting sublayers 4 can be metal types, such as MCrAlY (M=Ni, Co, Ni / Co) alloys, doped or undoped ternary element (e.g., Pt) nickel aluminide, β-NiAl type nickel aluminide (modified or unmodified with Pt, Hf, Zr, Y, Si or a combination of these elements), γ-Ni-γ'-Ni3Al alloy aluminides (modified or unmodified with Pt, Cr, Hf, Zr, Y, Si or a combination of these elements), for example, having a MAX phase (M n+1 AX n (n=1, 2, 3), where M=Sc, Y, La, Mn, Re, W, Hf, Zr, Ti; A=Groups IIIA, IVA, VA, VIA; X=C, N).

[0091] The first intermediate layer 3 directly covering the connecting sublayer 4 may contain a ceramic matrix selected from partially stabilized yttrium zirconium oxide, partially stabilized zirconium oxide by one or more rare earth elements (La->Yb), partially stabilized hafnium oxide by one or more rare earth elements (La->Yb), or yttrium zirconium oxide doped with tantalum or niobium.

[0092] The first intermediate layer 3 also ensures good lifetime performance under cyclic oxidation and thermal shock conditions. The first intermediate layer 3 has a thickness of 1µm to 1000µm, preferably 1µm to 100µm.

[0093] The additional intermediate layer with a ceramic matrix deposited on the first intermediate layer 3 may have the same chemical composition as the first intermediate layer 3, or have a different chemical composition that allows for environmental protection against the deposition of oxides of the CMAS (CaO-MgO-Al2O3-SiO2) type.

[0094] The additional intermediate layer forming the environmental protection layer contains compounds selected from the following: rare earth zirconates RE2Zr2O7 (RE = Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Yb, Dy, Ho, Er, Tm, Tb, Lu), partially / fully stabilized and possibly doped zirconium oxide, and A4B3O. 12 (A=Y→Lu and B=Zr,Hf)δ phase, spinel MgAl2O4, composites containing Y2O3 with ZrO2 and / or Al2O3 and / or TiO2, hexaaluminates, complex perovskites, spinels, rare earth monosilicates and disilicates (rare earth = Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu), and any other anti-CMAS compositions and all mixtures thereof.

[0095] The flash burning step is carried out on the entire blade, and therefore on the stack of layers formed by the connecting sub-layer 4, the intermediate layer 3 and the abrasive outer layer 5.

[0096] When the metal matrix 6 is of type MCrAlY, and the surface 2 of the blade tip 1 is nickel-based, the temperature of the oven for performing the flash firing step is between 700°C and 1000°C, preferably between 800°C and 900°C. The pressure inside the oven is between 25 MPa and 125 MPa, preferably between 50 MPa and 100 MPa. The cycle time is between 1 minute and 60 minutes, preferably between 5 minutes and 10 minutes. For this example and subsequent examples, the oven temperature corresponds to the temperature experienced by the blade tip 1. Similarly, the pressure inside the oven corresponds to the pressure applied to the blade tip 1.

[0097] When the substrate 6 is made of ceramic and the surface 2 of the blade tip 1 is nickel-based, the temperature of the oven for performing the flash firing step is between 900°C and 1300°C, preferably between 1000°C and 1100°C. The pressure inside the oven is between 25 MPa and 150 MPa, preferably between 50 MPa and 100 MPa. The cycle time is between 1 minute and 60 minutes, preferably between 5 minutes and 10 minutes.

[0098] The flash burning method allows for the functionalization of the blade tip 1 by applying a coating with grinding properties in a very short cycle (less than 60 minutes) without altering the original microstructure of the single-crystal superalloy of the blade tip 1. Exemplary embodiments are given below.

[0099] Figure 1 An example of a two-layer stack with a NiCoCrAlY-based metal matrix fabricated on the blade tip surface 2 of AM1 BS single-crystal superalloy is shown.

[0100] The NiCoCrAlY-based connecting sublayer 4, referred to as the binding sublayer, is deposited on the blade tip surface 2 and has a thickness of 80µm.

[0101] The connecting sublayer 4 can be deposited, for example, by thermal spraying, vapor deposition, or flash burning.

[0102] The NiCoCrAlY-based matrix 6 is in powder form and is intended to form the abrasive outer layer 5, which is then deposited onto the connector sublayer 4 by gravity.

[0103] A layer of powdered Al2O3 abrasive particles 7 was deposited by gravity onto a NiCoCrAlY-based matrix 6. The ratio between the median diameter of the abrasive particles 7 and the thickness of the matrix 6 was 0.82, or for a median abrasive particle diameter of 160 µm, the thickness of the matrix 6 was 192 µm. The ratio between the median diameter of the matrix 6 particles and the median diameter of the abrasive particles 7 was 3.125 × 10⁻⁶. -3 .

[0104] An abrasive outer layer 5 in the form of a powder bed stack is obtained on the blade tip surface 2.

[0105] Then, a flash burning method is applied to the stack to form an abrasive outer layer 5 containing surface inclusions of alumina Al2O3 as abrasive particles 7.

[0106] Figure 2 An example of multilayer stacking is shown on the tip surface 2 of a blade made of a single-crystal superalloy AM1BS.

[0107] The multilayer stack includes a NiCoCrAlY-based connector sublayer 4 with a thickness of 80µm, which is covered by a partially stabilized yttrium zirconium oxide intermediate layer 3 with a thickness of 50µm.

[0108] The connecting sublayer 4 and intermediate layer 3 can be deposited, for example, by thermal spraying, vapor deposition or flash burning.

[0109] The multilayer stack includes an outer abrasive layer 5 covering the intermediate layer 3. The outer abrasive layer 5 includes a matrix 6 made of partially stabilized yttrium zirconium oxide (8YPSZ) based ceramic, which contains inclusions of ZrO2-Al2O3 abrasive grains 7 in the volume.

[0110] The matrix 6, made of yttrium zirconium oxide-based ceramic in powder form, is mixed with ZrO2-Al2O3 abrasive particles 7 according to the previously described method.

[0111] The ratio of the median diameter of abrasive grain 7 to the thickness of matrix 6 is 0.77, corresponding to a matrix 6 thickness of 195 µm for a median diameter of abrasive grain 7 of 150 µm. The ratio of the median diameter of matrix 6 to the median diameter of abrasive grain 7 is 4.67. 10 -3 .

[0112] Then, a flash burning method is applied to the stacked layers to form an abrasive outer layer 5, which contains ZrO2-Al2O3 abrasive grains 7 inclusions in the volume.

[0113] During the flash calcination process, a fine alumina layer 8 (e≈0.5µm) is grown between the connector layer 4 and the intermediate layer 3 made of yttrium zirconium oxide through the oxidation of the connector layer 4.

[0114] Figure 3 Another example of a multilayer stack fabricated on the blade tip surface 2 made of a single-crystal superalloy AM1 BS is shown.

[0115] The multilayer stack includes a NiAlPt-based connector sublayer 4, which is fabricated by vapor phase aluminizing and has a thickness of 30µm.

[0116] An intermediate layer 3 with a thickness of 146 µm, made of partially stabilized yttrium zirconium oxide, covers the connecting sublayer 4.

[0117] A matrix 6 made of partially stabilized yttrium zirconium oxide (8YPSZ)-based ceramic, in powder form and intended to form the outer abrasive layer 5, is deposited onto the connector sublayer 4 by gravity deposition.

[0118] The SiC abrasive particles 7 in powder form were deposited onto the matrix 6 by gravity. The ratio between the median diameter of the abrasive particles and the thickness of the matrix 6 was 0.6, corresponding to a matrix 6 thickness of 4 µm for a median diameter of 2.5 µm for the abrasive particles 7. The ratio between the median diameter of the particles in the matrix 6 and the median diameter of the abrasive particles 7 was 0.28.

[0119] Then, a flash burning method is applied to the stacked layers to form an abrasive outer layer 5 containing surface inclusions of SiC abrasive grains 7.

[0120] During the flash burning process, a fine alumina layer (e≈0.5µm) is grown between the connector layer 4 and the intermediate layer 3 through the oxidation of the connector layer 4.

[0121] As a variation, this deposition method can be applied to functionalize turbine blade tips made of CMC (ceramic matrix composites) using an abrasive coating manufactured by flash firing.

[0122] The layer stack includes a connecting sublayer 4 based on silicon, based on boron-doped silicon, based on hafnium-doped or rare earth oxides ((RE=Y, Yb, Gd)) and doped with dopants (Zr, Hf, Ta, N, Al), SiAlON and Si-HfB2, SiC-HfO2 or SiC-HfO2-HfB2.

[0123] The connecting sublayer 4 is formed, for example, by PVD (physical vapor deposition), by APS (atmospheric plasma spraying), by HVOF (high-velocity oxygen fuel) spraying using a supersonic flame, by LPPS (low-pressure plasma spraying) or its derivatives, by IPS (inert plasma spraying) plasma spraying under an inert atmosphere, by CVD (chemical vapor deposition), by vapor phase aluminizing APVS, by electrolytic deposition, slurry, sol-gel, flash burning and any other suitable forming method.

[0124] The layer stack includes one or more intermediate layers 3, called environmental protection layers, deposited on connecting sublayers 4, selected from rare earth disilicates Re₂Si₂O₇ (Re=RE=Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Yb, Dy, Ho, Er, Tm, Tb, Lu) and their co-dopers, rare earth silicates Re₂SiO₅ and their co-dopers, barium strontium aluminum silicates (BSAS, (BaO)₂x.(SrO)₂) 1- x Al2O3.2SiO2 (where 0≤x≤1), hafnium-doped rare earth silicates, hafnium-doped rare earth silicates, mullite, spinel MgAl2O4, garnet (Y3Al5O4) 12 ), partially / fully stable and possibly doped zirconium oxide, δ phase A4B3O 12 (A=Y→Lu and B=Zr, Hf), composites containing Y2O3 with ZrO2 and / or Al2O3 and / or TiO2, hexaaluminates, complex perovskites, and any other environmental barrier compositions, and all mixtures thereof. The latter is achieved by flash calcination or by any other deposition method previously described for connecting sublayer 4.

[0125] The intermediate layer 3 has a thickness between 1µm and 1000µm.

[0126] The layer stack includes an abrasive outer layer 5, which contains a matrix 6 and abrasive grains 7 included in the matrix 6 and on its surface and / or in its volume.

[0127] Flash burning is applied to the outer abrasive layer 5 to obtain an abrasive coating with a thickness between 3µm and 400µm.

[0128] The ceramic matrix 6 of the integrated abrasive grains 7 is based on the particles previously described for the case of the blade tip 1 made of metal.

[0129] The abrasive particles 7 are the same as those described for the metal blade tip 1.

[0130] The different methods of applying (in powder form, encapsulated powder form, or printed layer form) and manufacturing the functionalized abrasive outer layer 5 in terms of the thickness of the matrix 6, the size of the abrasive grains 7, the chemical composition of the abrasive grains 7, and the inclusions in the particles 7 are the same as those previously described for the case of application to the end of the metal blade 1.

[0131] For consolidation via flash firing, the oven temperature for introducing the blade tip 1, which is covered by a stacked layer, is between 900°C and 1500°C, preferably between 1200°C and 1400°C. The pressure in the oven is between 25 MPa and 150 MPa, preferably between 50 MPa and 100 MPa. The cycle time is between 1 minute and 60 minutes, preferably between 5 minutes and 10 minutes.

[0132] The aforementioned variations describe examples of abrasive outer layer 5 being deposited directly onto surface 2 of blade tip 1, or deposited onto metal-based or ceramic-based connecting sublayer 4 previously deposited onto surface 2 of blade tip 1, or deposited onto intermediate layer 3. A single flash firing step is performed on the layer stack containing abrasive outer layer 5.

[0133] As a variant, the abrasive outer layer 5 is pre-formed in a pre-forming mold.

[0134] The deposition method then includes the steps of depositing a metal-based or ceramic-based matrix 6 into a preform mold and depositing a layer of abrasive particles 7 to intercalate the abrasive particles 7 on the surface of the matrix 6. The preform mold is adapted to the size and geometry of the blade tip 1 to be functionalized.

[0135] As a variation, the powder constituting matrix 6 and the abrasive powder 7 can be mixed and deposited into a preform mold to incorporate the abrasive 7 within the volume and inside the surface of matrix 6.

[0136] The matrix 6 and abrasive 7 layers can be in powder form or in the form of encapsulated powder encapsulated in a polymer adhesive-based matrix by fused wire deposition, or formed by a printed layer.

[0137] A preliminary flash firing step is performed on the abrasive outer layer 5 in the preforming mold to obtain the preformed abrasive outer layer.

[0138] The pre-formed abrasive outer layer is then deposited into a sintering mold and deposited on the surface 2 of the blade tip 1, followed by a flash firing step of the pre-formed abrasive outer layer.

[0139] As in the aforementioned example, the surface 2 of the blade tip 1 can be covered by a metal-based or ceramic-based connecting sublayer 4 previously deposited on the surface 2 of the blade tip 1, as previously described. The connecting sublayer 4 can also be covered by an intermediate layer 3.

[0140] The pre-formed abrasive outer layer and other layers that may be deposited on the surface 2 of the blade tip 1 undergo a second flash during the flash burning step to form the final abrasive coating.

[0141] As a variation, when the blade tip 1 is metal, the abrasive outer layer 5 can be preformed on a powder bed made of a nickel-based superalloy with the same chemical composition as the blade tip 1.

[0142] Then, before depositing the abrasive outer layer 5 using the different methods and forms described previously, a bed of high-temperature alloy powder is pre-deposited into a preform mold. The thickness of the nickel-based high-temperature alloy powder bed is between 0.5 mm and 5 mm.

[0143] A preliminary step of flash burning is applied to the powder bed and abrasive outer layer 5 made of high-temperature alloy to obtain a preformed coating comprising a high-temperature alloy base layer covered by a preformed abrasive outer layer.

[0144] A pre-formed coating is deposited onto the surface 2 of the blade tip 1 and undergoes a second flash firing during the flash firing step to form the final abrasive coating.

[0145] As a variation, the abrasive outer layer 5 can be preformed by first flash firing on a substrate made of a nickel-based superalloy with the same chemical composition as the superalloy of the blade tip 1 in a preforming mold adapted to the size and geometry of the blade tip 1 to be functionalized.

[0146] A substrate made of high-temperature alloy is machined to the dimensions and geometry of the blade tip 1 to be functionalized. The minimum thickness of the substrate made of high-temperature alloy is between 0.5 mm and 5 mm.

[0147] When the blade tip 1 is made of ceramic, the substrate is made of ceramic and machined to the dimensions and geometry of the blade tip 1 to be functionalized. The minimum thickness of the ceramic substrate is between 0.5 mm and 5 mm.

[0148] Although the invention has been described with reference to specific exemplary embodiments, it will be apparent that modifications and changes can be made to these examples without departing from the overall scope of the invention as defined by the claims. Specifically, features of the different embodiments illustrated / mentioned can be combined in other embodiments. Therefore, this specification and the accompanying drawings should be considered in an illustrative rather than restrictive sense.

[0149] It is equally obvious that all features described by the reference method can be converted into a device individually or in combination, and conversely, all features described by the reference device can be converted into a method individually or in combination.

Claims

1. A method for depositing an abrasive coating on the tip (1) of an aircraft turbine blade, said blade tip being made of metal or ceramic, characterized in that, The method includes: - The step of positioning the sintering mold on the end of the blade (1); - The step of covering the surface (2) of the blade tip (1) defined by the sintering mold with an abrasive outer layer (5) comprising a metal-based or ceramic-based matrix (6) and abrasive grains (7); and - The step of performing flash burning on the outer abrasive layer (5) to form the blade tip (1) covered by the abrasive coating.

2. The method according to claim 1, characterized in that, The abrasive outer layer (5) is obtained by first depositing a metal-based or ceramic-based powder layer to form a matrix (6) in the form of a powder layer, and then depositing an abrasive (7) powder layer on the matrix (6) a second time.

3. The method according to claim 1, characterized in that, The abrasive outer layer (5) is obtained by first depositing a metal-based or ceramic-based powder layer encapsulated in a polymer adhesive matrix using a fused wire deposition method to form a matrix (6) in the form of encapsulated powder, and then depositing a layer of abrasive particles (7) encapsulated in a polymer adhesive matrix onto the matrix (6) a second time using a fused wire deposition method.

4. The method according to claim 1, characterized in that, The abrasive outer layer (5) is obtained by first deposition through printing a metal or ceramic substrate to form a printing matrix (6), and by second deposition through printing the abrasive grains (7) onto the printing matrix (6).

5. The method according to claim 1, characterized in that, The abrasive outer layer (5) is obtained by mixing abrasive powder (7) with a matrix (6) of metal-based or ceramic-based powder.

6. The method according to any one of claims 1 to 5, characterized in that, The abrasive outer layer (5) is deposited directly onto the surface (2) of the blade tip (1), or onto the metal-based or ceramic-based connecting sublayer (4) previously deposited on the surface (2) of the blade tip (1), or onto the metal-based or ceramic-based intermediate layer (3) deposited between the connecting sublayer (4) and the abrasive outer layer (5).

7. The method according to any one of claims 1 to 5, characterized in that, The method includes, prior to the step of covering the surface (2) of the blade tip (1) with the abrasive outer layer (5): a step of depositing the abrasive outer layer into a preform mold, a preliminary step of flash burning on the abrasive outer layer (5) to form a preformed abrasive outer layer, and a step of depositing the preformed abrasive outer layer into the sintering mold, the flash burning step being performed on the preformed abrasive outer layer.

8. The method according to any one of claims 1 to 7, characterized in that, The ratio between the median diameter of the abrasive grain (7) and the thickness of the matrix (6) is between 0.6 and 0.9, and the thickness of the outer abrasive layer (5) is between 3µm and 400µm.

9. The method according to any one of claims 1 to 8, characterized in that, The ratio between the median diameter of the particles in the matrix (6) and the median diameter of the abrasive grains (7) is between 0.002 and 0.

4.

10. The method according to any one of claims 1 to 9, characterized in that, When the matrix (6) is metal and the surface (2) of the blade tip (1) is nickel-based, the oven temperature for performing the flash firing step is between 700°C and 1000°C, preferably between 800°C and 900°C, the pressure inside the oven is between 25MPa and 125MPa, preferably between 50MPa and 100MPa, and the cycle time is between 1 minute and 60 minutes, preferably between 5 minutes and 10 minutes.

11. The method according to any one of claims 1 to 9, characterized in that, When the matrix (6) is a ceramic matrix (6) and the surface (2) of the blade tip (1) is nickel-based, the oven temperature for performing the flash firing step is between 900°C and 1300°C, preferably between 1000°C and 1100°C, the pressure inside the oven is between 25MPa and 150MPa, preferably between 50MPa and 100MPa, and the cycle time is between 1 minute and 60 minutes, preferably between 5 minutes and 10 minutes.

12. The method according to any one of claims 1 to 9, characterized in that, When the substrate (6) and the surface (2) of the blade tip (1) are made of ceramic, the oven temperature for performing the flash firing step is between 900°C and 1500°C, preferably between 1200°C and 1400°C, the pressure inside the oven is between 25 MPa and 150 MPa, preferably between 50 MPa and 100 MPa, and the cycle time is between 1 minute and 60 minutes, preferably between 5 minutes and 10 minutes.

13. An aircraft turbine blade, comprising at least one blade tip (1), characterized in that, The blade tip (1) comprises an abrasive coating obtained by the method according to any one of claims 1 to 12.

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