Abradable sealing coating and preparation method thereof

Abstract

The invention provides an abradable sealing coating and a preparation method thereof, and relates to the field of coatings. The abradable sealing coating comprises a ceramic substrate layer, a nickel-based middle layer and an aluminum-based surface layer which are arranged in a stacked mode. The materials for forming the ceramic substrate layer comprise 8YSZ, NiCoCrAlY, a doping material and a pore forming agent, and the doping material comprises at least one of graphene and a carbon nanotube; the material for forming the nickel-based intermediate layer comprises NiCrAlY, and the material for forming the aluminum-based surface layer comprises aluminum-silicon alloy and graphite. The abradable sealing coating has the characteristic of'soft-medium-hard 'from outside to inside, and can meet the multi-dimensional requirements of an aero-engine sealing scene.

Description

Technical Field

[0001] This application relates to the field of coatings, and more particularly to an abrasive sealing coating and a method for preparing the same. Background Technology

[0002] In high-end equipment fields such as aerospace and gas turbines, the efficient and stable operation of engines is highly dependent on the performance of the sealing system. As a key technology for reducing gap leakage and improving energy utilization efficiency, the comprehensive performance of wear-resistant sealing coatings directly affects the overall efficiency and service life of the equipment.

[0003] Currently, traditional sealing coatings face severe challenges in actual working conditions. At low temperatures, coatings with ceramic as the main component often have poor abrasiveness due to their high hardness, which can easily cause excessive wear of mating metal parts and even lead to sealing failure. At high temperatures, although some coatings have enhanced abrasiveness due to the micro-melting of the material, the overall decrease in hardness is difficult to accurately match the requirements of the working conditions, which may lead to excessive wear or poor sealing.

[0004] As engines evolve towards higher thrust-to-weight ratios and higher speeds, the internal temperature field distribution becomes increasingly complex. From the low-temperature environment during startup to the high-temperature state during continuous operation, coatings need to maintain stable and adaptable wear-resistance across a wide temperature range. Existing single-system coatings can no longer achieve a dynamic performance balance of "soft and easily wear-resistant at low temperatures, and hardened and wear-promoted at high temperatures." This leads to frequent problems such as reduced sealing efficiency and accelerated component wear during start-stop cycles and continuous operation, increasing maintenance costs and posing a potential threat to the operational safety of the equipment.

[0005] Therefore, developing a coating system that can respond to temperature changes and achieve adaptive adjustment of wear-resistant properties has become an urgent need to break through existing technological bottlenecks and improve the core performance of high-end equipment. Summary of the Invention

[0006] The purpose of this application is to provide an abrasive sealing coating and a method for preparing the same, in order to solve the above-mentioned problems.

[0007] To achieve the above objectives, this application adopts the following technical solution: A wear-resistant sealing coating includes a ceramic substrate layer, a nickel-based intermediate layer and an aluminum-based surface layer stacked together; The materials forming the ceramic substrate include 8YSZ, NiCoCrAlY, dopants, and pore-forming agents, wherein the dopants include at least one of graphene and carbon nanotubes; The materials forming the nickel-based interlayer include NiCrAlY; The materials forming the aluminum-based surface layer include aluminum-silicon alloys and graphite.

[0008] According to embodiments of this application, the volume of 8YSZ accounts for 60-80% of the total volume of 8YSZ and NiCoCrAlY, the volume of the doped material accounts for 0.5-2% of the total volume of 8YSZ and NiCoCrAlY, and the mass of the pore-forming agent accounts for 1-3 wt% of the total mass of 8YSZ and NiCoCrAlY. The pore-forming agent includes ammonium bicarbonate; The NiCoCrAlY comprises 15-25 wt% Cr, 5-15 wt% Al, 6-16 wt% Co, 0.1-1.0 wt% Y, and the balance Ni. The NiCrAlY comprises 15-20 wt% Cr, 8-12 wt% Al, 0.3-0.8 wt% Y, and the balance Ni; The volume of the graphite accounts for 5-15% of the total volume of the aluminum-silicon alloy and the graphite; The silicon content in the aluminum-silicon alloy is 8-12 wt%.

[0009] According to embodiments of this application, the porosity of the ceramic substrate layer is 20-30%; The porosity of the nickel-based intermediate layer is 5-15%; The porosity of the aluminum-based surface layer is 20-40%.

[0010] According to an embodiment of this application, the HR45Y hardness of the ceramic substrate layer is greater than that of the nickel-based intermediate layer, and the HR45Y hardness of the nickel-based intermediate layer is greater than that of the aluminum-based surface layer.

[0011] According to an embodiment of this application, the HR45Y hardness of the ceramic substrate layer is 70-85; The nickel-based intermediate layer includes a first intermediate layer and a second intermediate layer stacked together. The first intermediate layer is located between the ceramic substrate layer and the second intermediate layer. The hardness of the first intermediate layer is greater than that of the second intermediate layer. The HR45Y hardness of the first intermediate layer is 55-66, and the HR45Y hardness of the second intermediate layer is 49-55. The HR45Y hardness of the aluminum-based surface layer is 40-50.

[0012] It should be noted that the HR45Y hardness in this application is measured at room temperature and refers to room temperature hardness.

[0013] According to embodiments of this application, the thickness of the aluminum-based surface layer is 50-100 μm, the thickness of the nickel-based intermediate layer is 100-200 μm, and the thickness of the ceramic substrate layer is 150-300 μm; And / or, the thickness ratio of the aluminum-based surface layer to the nickel-based intermediate layer and the ceramic substrate layer is 1:2:3 to 1:3:5.

[0014] According to an embodiment of this application, the thickness ratio of the first intermediate layer to the second intermediate layer is 1:(0.5-1.5).

[0015] This application also provides a method for applying an abrasive sealing coating as described above, comprising: Pre-treatment of the metal substrate by sandblasting; A ceramic substrate layer was deposited on a pretreated metal substrate using a mixture of 8YSZ, NiCoCrAlY, doping materials and pore-forming agents as raw materials and a three-anode plasma spraying process. Using NiCrAlY powder as the spraying material, a nickel-based intermediate layer is formed on the ceramic substrate using the HVOF process; An aluminum-based surface layer is formed on the nickel-based intermediate layer using a mixture of aluminum-silicon alloy and graphite as raw materials and a cold spraying process.

[0016] According to an embodiment of this application, the surface roughness Ra of the pretreated metal substrate is 3.2-6.3 μm.

[0017] According to embodiments of this application, the preparation method satisfies at least one of the following conditions: (1) The deposition of a ceramic substrate layer on the pretreated metal substrate using a trianodine plasma spraying process includes: spraying the pretreated metal substrate using a trianodine plasma spraying process, and then transferring it to a vacuum annealing furnace for annealing treatment; wherein, the spraying parameters for spraying the pretreated metal substrate using a trianodine plasma spraying process include: independently controlling the main arc power of 40-60kW and the auxiliary arc power of 10-20kW, the flow ratio of plasma gas argon to hydrogen is (4-8):1, the spraying distance is 100-150mm, the powder feeding rate is 22-28g / min, the spray gun moving speed is 75-85mm / s, and the required thickness is achieved by controlling the number of sprayings; the annealing treatment includes: heating to 780-820℃ at 3-7℃ / min, and holding at 780-820℃ for 1.5-2.5h; (2) The formation of a nickel-based intermediate layer on the ceramic substrate using the HVOF process includes: using a pulsed HVOF mode with a pulse frequency of 50-100Hz, firstly spraying to form a first intermediate layer under the following conditions: kerosene flow rate 16-20L / h, O2 flow rate 340-360L / min, and powder feeding rate 26-30g / min; then spraying to form a second intermediate layer under the following conditions: kerosene flow rate 16-20L / h, O2 flow rate 310-330L / min, and powder feeding rate 20-24g / min; controlling the coating thickness by adjusting the number of sprayings until the required thickness of the first and second intermediate layers is achieved. (3) Forming an aluminum-based surface layer on the nickel-based intermediate layer using a cold spraying process includes: using a dual powder feeding cold spraying system, with nitrogen as the working gas, a gas pressure of 1-2 MPa, a gas temperature of ≤100℃, a powder feeding rate ratio of aluminum-silicon alloy to graphite of 8:1 to 5:1, a total powder feeding rate of 21-25 g / min, a spraying distance of 20-30 mm, a nozzle moving speed of 90-110 mm / s, and adjusting the number of sprayings until the required thickness is achieved.

[0018] According to an embodiment of this application, the method further includes: using a Rockwell hardness online monitoring system during the formation of the ceramic substrate layer, the nickel-based intermediate layer and the aluminum-based surface layer, and measuring the HR45Y hardness of the coating surface in real time by laser refraction method.

[0019] Compared with the prior art, the beneficial effects of this application include: 1. The hardness of the aluminum-based surface layer, nickel-based intermediate layer, and ceramic substrate layer in this application are coordinated to precisely match the temperature range of the aero-engine from low-temperature start-up to high-temperature operation: the soft aluminum-based surface layer wears preferentially in the low-temperature range, the nickel-based intermediate layer experiences controllable wear in the medium-temperature range, and the ceramic substrate layer achieves adaptive hardness reduction through pore collapse in the high-temperature range.

[0020] 2. The porosity of the aluminum-based surface layer, nickel-based intermediate layer, and ceramic substrate layer in this application complements each other: the interconnected honeycomb pores (20-30%) of the aluminum-based surface layer cause the wear debris to peel off in thin flakes, the low-porosity dense structure (5-15%) of the nickel-based intermediate layer provides thermal stress buffering, and the closed-pore structure (20-40%) of the ceramic substrate layer collapses in a directional manner at high temperatures to form a nanoscale lubricating surface, which improves the wear rate by 5-8 times compared with traditional dense coatings.

[0021] 3. This application introduces graphene or carbon nanotubes as dopants into the ceramic substrate layer. By utilizing the "elastic support framework" effect of the dopants, the coarsening of 8YSZ grains and excessive pore collapse at high temperatures can be suppressed. This results in a hardness retention rate of ≥88% after 100 cycles of thermal cycling at 1000℃, and a lifespan that is more than 3 times longer than that of traditional YSZ coatings. This solves the industry problem of unstable high-temperature wear of ceramic-based materials and significantly improves the efficiency, stability and service life of aero-engine sealing systems.

[0022] 4. This application can prepare a wearable sealing coating with excellent performance by using a combination of three-anode plasma spraying, HVOF and cold spraying. Detailed Implementation

[0023] As used in this article: "Prepared from" is synonymous with "comprising". The terms "comprising", "including", "having", "containing", or any other variations thereof as used herein are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0024] The conjunction "composed of..." excludes any unspecified elements, steps, or components. If used in a claim, this phrase makes the claim closed, excluding materials other than those described, except for associated conventional impurities. When the phrase "composed of..." appears in a clause of the body of a claim rather than immediately following it, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0025] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1–5” is disclosed, the described range should be interpreted as including ranges “1–4”, “1–3”, “1–2”, “1–2 and 4–5”, “1–3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range.

[0026] In these embodiments, unless otherwise specified, the portions and percentages are all by weight.

[0027] "Parts by mass" refers to the basic unit of measurement that expresses the mass ratio of multiple components. One part can represent any unit mass, such as 1g or 2.689g. If we say that component A has "a" parts by mass and component B has "b" parts by mass, it means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, it can mean that the mass of component A is aK and the mass of component B is bK (where K is any number representing a multiplier). It is important to understand that, unlike parts by mass, the sum of the mass parts of all components is not limited to 100 parts.

[0028] "And / or" is used to indicate that one or both of the described situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0029] A wear-resistant sealing coating includes a ceramic substrate layer, a nickel-based intermediate layer and an aluminum-based surface layer stacked together; The materials forming the ceramic substrate include 8YSZ (8% Y2O3 stabilized ZrO2), NiCoCrAlY, dopants, and pore-forming agents, wherein the dopants include at least one of graphene and carbon nanotubes; The materials forming the nickel-based interlayer include NiCrAlY; The materials forming the aluminum-based surface layer include aluminum-silicon alloys and graphite.

[0030] The abrasive sealing coating of this application can achieve layer-by-layer controllable abrasion as the temperature rises during the start-up process of an aero-engine from room temperature to above 1000°C.

[0031] According to embodiments of this application, the volume of 8YSZ accounts for 60-80% of the total volume of 8YSZ and NiCoCrAlY, the volume of the doped material accounts for 0.5-2% of the total volume of 8YSZ and NiCoCrAlY, and the mass of the pore-forming agent accounts for 1-3 wt% of the total mass of 8YSZ and NiCoCrAlY. For example, the volume of 8YSZ accounts for any value between 60%, 65%, 70%, 75%, 80%, or 60-80% of the total volume of 8YSZ and NiCoCrAlY; the volume of the doped material accounts for any value between 0.5%, 1%, 1.5%, 2%, or 0.5-2% of the total volume of 8YSZ and NiCoCrAlY; and the mass of the pore-forming agent accounts for any value between 1wt%, 2wt%, 3wt%, or 1-3wt% of the total mass of 8YSZ and NiCoCrAlY.

[0032] Graphene and carbon nanotubes have high elasticity and thermal conductivity. As doping materials, graphene and / or carbon nanotubes can suppress the coarsening of 8YSZ grains at high temperatures and improve the high-temperature wear stability of the coating.

[0033] The pore-forming agent includes ammonium bicarbonate; In some embodiments, NiCoCrAlY comprises 15-25 wt% Cr, 5-15 wt% Al, 6-16 wt% Co, 0.1-1.0 wt% Y, and the balance Ni.

[0034] For example, the Cr content in NiCoCrAlY is 15 wt%, 17 wt%, 20 wt%, 22 wt%, 25 wt%, or any value between 15 and 25 wt%; the Al content in NiCoCrAlY is 5 wt%, 7 wt%, 10 wt%, 12 wt%, 15 wt%, or any value between 5 and 15 wt%; the Co content in NiCoCrAlY is 6 wt%, 8 wt%, 10 wt%, 12 wt%, 15 wt%, 16 wt%, or any value between 6 and 16 wt%; and the Y content in NiCoCrAlY is 0.1 wt%, 0.3 wt%, 0.5 wt%, 0.7 wt%, 1.0 wt%, or any value between 0.1 and 1.0 wt%.

[0035] In some embodiments, NiCrAlY comprises 15-20 wt% Cr, 8-12 wt% Al, 0.3-0.8 wt% Y, and the balance Ni.

[0036] For example, the Cr content in NiCrAlY is 15 wt%, 17 wt%, 20 wt%, or any value between 15 and 20 wt%; the Al content in NiCrAlY is 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, or any value between 8 and 12 wt%; and the Y content in NiCrAlY is 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, or any value between 0.3 and 0.8 wt%.

[0037] The volume of the graphite accounts for 5-15% of the total volume of the aluminum-silicon alloy and the graphite; for example, the volume of the graphite accounts for any value between 5%, 7%, 10%, 12%, 15% or 5-15% of the total volume of the aluminum-silicon alloy and the graphite.

[0038] The silicon content in the aluminum-silicon alloy is 8-12 wt%. For example, the silicon content in the aluminum-silicon alloy is 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, or any value between 8 and 12 wt%.

[0039] According to an embodiment of this application, the porosity of the ceramic substrate is 20-30%; the ceramic substrate will undergo directional collapse at high temperature to form a nano-lubricating surface, which is beneficial to reducing the high-temperature wear rate.

[0040] For example, the porosity of the ceramic substrate can be any value between 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, or 20-30%.

[0041] The porosity of the nickel-based intermediate layer is 5-15%; for example, the porosity of the nickel-based intermediate layer is any value between 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, or 5-15%.

[0042] In some embodiments, the porosity of the first intermediate layer is 5-8%, and the porosity of the second intermediate layer is 8-15%. For example, the porosity of the first intermediate layer is any value between 5%, 6%, 7%, 8%, or 5-8%, and the porosity of the second intermediate layer is any value between 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, or 5-15%.

[0043] The porosity of the aluminum-based surface layer is 20-40%. For example, the porosity of the aluminum-based surface layer is any value between 20%, 25%, 30%, 35%, 40%, or 20-40%.

[0044] According to an embodiment of this application, the HR45Y hardness of the ceramic substrate layer is greater than that of the nickel-based intermediate layer, and the HR45Y hardness of the nickel-based intermediate layer is greater than that of the aluminum-based surface layer.

[0045] According to an embodiment of this application, the HR45Y hardness of the ceramic substrate is 70-85; for example, the HR45Y hardness of the ceramic substrate is 70, 72, 75, 77, 80, 82, 85 or any value between 70 and 85.

[0046] The nickel-based interlayer includes a first interlayer and a second interlayer stacked together. The first interlayer is located between the ceramic substrate and the second interlayer. The hardness of the first interlayer is greater than that of the second interlayer. The HR45Y hardness of the first interlayer is 55-66, and the HR45Y hardness of the second interlayer is 49-55. For example, the HR45Y hardness of the first interlayer can be any value between 55, 57, 60, 62, 65, 66, or 55-66, and the HR45Y hardness of the second interlayer can be any value between 49, 50, 51, 52, 53, 54, 55, or 49-55. The hardness of the nickel-based interlayer gradually decreases with increasing temperature, which can achieve stable control of the wear rate in the mid-temperature range (0.5-1.2 mg / N·m).

[0047] The HR45Y hardness of the aluminum-based surface layer is 40-50. The HR45Y hardness of the aluminum-based surface layer is any value between 40, 42, 45, 47, 50, or 40-50.

[0048] The abrasive sealing coating of this application has a "soft-medium-hard" characteristic from the outside to the inside, which can meet the multi-dimensional requirements of aero-engine sealing scenarios. The outer aluminum-based surface layer is soft, and the low-temperature abrasion protection aluminum-based surface layer has a low hardness (HR45Y hardness is 40-50). During the low-temperature range of engine startup (≤500℃), it preferentially scrapes against the blades to generate controllable abrasion, avoiding direct damage to the blades by the hard coating. Its hardness gradually decreases with increasing temperature, which is consistent with the requirement of "allowing moderate abrasion to protect the substrate" in the low-temperature range. The nickel-based intermediate layer adopts a medium-hard design. In the 500-900℃ range, the medium-temperature stress buffer nickel-based alloy may undergo anomalous hardening due to γ' phase precipitation. However, the nickel-based intermediate layer of this application weakens this effect through composition control, so that the hardness remains at a medium level in the medium-temperature range (HR45Y hardness of the nickel-based intermediate layer is 49-66). In this range, the nickel-based intermediate layer can both support the structure after the outer layer is worn and absorb the shear stress generated by thermal cycling through moderate hardness, preventing coating delamination. The ceramic substrate layer adopts a hard design with high hardness (HR45Y hardness is 70-85), which provides structural support for the entire coating. At high temperature, the hardness decreases due to pore collapse, but it is still higher than that of the nickel-based intermediate layer. At this time, the porous structure softens and forms a "self-lubricating surface", which not only ensures the adaptability of the sealing gap, but also avoids the overall failure of the coating due to excessively low hardness.

[0049] At low temperatures, the aluminum-based surface is preferentially scraped by the blades, forming thin flake-like abrasive debris (thickness ≤ 5 μm), thus avoiding damage to the blades.

[0050] According to embodiments of this application, the thickness of the aluminum-based surface layer is 50-100 μm, the thickness of the nickel-based intermediate layer is 100-200 μm, and the thickness of the ceramic substrate layer is 150-300 μm; For example, the thickness of the aluminum-based surface layer can be any value between 50μm, 60μm, 70μm, 80μm, 90μm, 100μm or 50-100μm; the thickness of the nickel-based intermediate layer can be any value between 100μm, 110μm, 120μm, 130μm, 140μm, 150μm, 160μm, 170μm, 180μm, 190μm, 200μm or 100-200μm; and the thickness of the ceramic substrate layer can be any value between 150μm, 170μm, 200μm, 220μm, 250μm, 270μm, 300μm or 150-300μm.

[0051] The ceramic substrate, nickel-based intermediate layer, and aluminum-based surface layer of this application have complementary material properties. The aluminum-based surface layer is soft and has high thermal conductivity, which can solve the problem of low-temperature wear, but its high-temperature strength is insufficient. Therefore, it is designed as the outermost layer and the thinnest layer (50-100μm), only undertaking the function of initial wear. The nickel-based intermediate layer has the characteristics of stable strength at medium temperature and good thermal expansion matching. As a "transition layer," it balances the stress between the inner and outer layers. Its moderate thickness (100-200μm) provides a buffer. The ceramic substrate layer has the characteristics of high-temperature insulation and high hardness. As a support layer, it needs to be thick enough (150-300μm). The porous structure reduces the hardness at room temperature and avoids "hard damage to the blades."

[0052] And / or, the thickness ratio of the aluminum-based surface layer to the nickel-based intermediate layer and the ceramic substrate layer is 1:2:3 to 1:3:5.

[0053] For example, the thickness ratio of the aluminum-based surface layer to the nickel-based intermediate layer and the ceramic substrate layer is 1:2:3, 1:2:4, 1:2:5, 1:3:3, 1:3:4, 1:3:5 or any value between 1:2:3 and 1:3:5.

[0054] According to an embodiment of this application, the thickness ratio of the first intermediate layer to the second intermediate layer is 1:(0.5-1.5); for example, the thickness ratio of the first intermediate layer to the second intermediate layer is any value between 1:0.5, 1:1, 1:1.5 or 1:(0.5-1.5).

[0055] In some embodiments, the porosity of the first intermediate layer is less than that of the second intermediate layer; further, the porosity of the first intermediate layer is 5-10%, and the porosity of the second intermediate layer is 10-15%.

[0056] This application also provides a method for preparing the wear-resistant sealing coating as described above, comprising: Pre-treatment of the metal substrate by sandblasting; A ceramic substrate layer was deposited on a pretreated metal substrate using a mixture of 8YSZ, NiCoCrAlY, doping materials and pore-forming agents as raw materials and a three-anode plasma spraying process. Using NiCrAlY powder as the spraying material, a nickel-based intermediate layer is formed on the ceramic substrate using the HVOF process; specifically, the preparation of the nickel-based intermediate layer includes: using NiCrAlY powder as the spraying material, forming a first intermediate layer on the ceramic substrate using the HVOF process; and then using NiCrAlY powder as the spraying material, forming a second intermediate layer on the first intermediate layer using the HVOF process. An aluminum-based surface layer is formed on the nickel-based intermediate layer using a mixture of aluminum-silicon alloy and graphite as raw materials and a cold spraying process.

[0057] According to an embodiment of this application, the surface roughness Ra of the pretreated metal substrate is 3.2-6.3 μm.

[0058] In some embodiments, the pretreatment of the metal substrate by sandblasting includes: pretreatment of the metal substrate (such as GH4169 high-temperature alloy) by sandblasting, with specific parameters as follows: using 80-120 mesh brown corundum abrasive (Al2O3 content ≥95%), compressed air pressure 0.4-0.6MPa, distance between the sandblasting gun and the substrate surface 100-150mm, spray angle 70-80°, and moving speed 50-100mm / s; after sandblasting, the residual abrasive particles are blown away with 0.3MPa compressed air to ensure that the surface roughness Ra of the pretreated metal substrate is 3.2-6.3μm.

[0059] According to embodiments of this application, the preparation method satisfies at least one of the following conditions: (1) The deposition of a ceramic substrate layer on the pretreated metal substrate using a trianodine plasma spraying process includes: spraying the pretreated metal substrate using a trianodine plasma spraying process, and then transferring it to a vacuum annealing furnace for annealing treatment; wherein, the spraying parameters for spraying the pretreated metal substrate using a trianodine plasma spraying process include: independently controlling the main arc power of 40-60kW and the auxiliary arc power of 10-20kW, the flow ratio of plasma gas argon to hydrogen is (4-8):1, the spraying distance is 100-150mm, the powder feeding rate is 22-28g / min, the spray gun moving speed is 75-85mm / s, and the required thickness is achieved by controlling the number of sprayings; the annealing treatment includes: in a vacuum degree ≤1×10 -3 Under Pa conditions, the temperature is increased to 780-820℃ at a rate of 3-7℃ / min, held at 780-820℃ for 1.5-2.5h, and then cooled in the furnace to below 100℃ before being removed from the furnace. Furthermore, this step also includes a raw material mixing step, in which 8YSZ powder is mixed with NiCoCrAlY powder, pore-forming agent and dopant material using a planetary ball mill at 300 r / min for 2 h (agate ball media).

[0060] In this step, the flow rate of argon plasma is 40-80 L / min, and the flow rate of hydrogen plasma is 8-12 L / min.

[0061] The particle size of 8YSZ powder is 50-100μm, and the particle size of NiCoCrAlY powder is 30-60μm.

[0062] (2) The formation of a nickel-based intermediate layer on the ceramic substrate using the HVOF process includes: using a pulsed HVOF mode with a pulse frequency of 50-100Hz, firstly spraying to form a first intermediate layer under the following conditions: kerosene flow rate 16-20L / h, O2 flow rate 340-360L / min, and powder feeding rate 26-30g / min; then spraying to form a second intermediate layer under the following conditions: kerosene flow rate 16-20L / h, O2 flow rate 310-330L / min, and powder feeding rate 20-24g / min; controlling the coating thickness by adjusting the number of sprayings until the required thickness of the first and second intermediate layers is achieved. (3) Forming an aluminum-based surface layer on the nickel-based intermediate layer using a cold spraying process includes: using a dual powder feeding cold spraying system, with nitrogen as the working gas, a gas pressure of 1-2 MPa, a gas temperature of ≤100℃, a powder feeding rate ratio of aluminum-silicon alloy to graphite of 8:1 to 5:1, a total powder feeding rate of 21-25 g / min, a spraying distance of 20-30 mm, a nozzle moving speed of 90-110 mm / s, and adjusting the number of sprayings until the required thickness is achieved.

[0063] In the process of forming the ceramic substrate layer, the nickel-based intermediate layer and the aluminum-based surface layer, the method further includes using a Rockwell hardness online monitoring system to monitor the thickness of the ceramic substrate layer, the nickel-based intermediate layer and the aluminum-based surface layer in real time, and stopping the spraying when the thickness of the ceramic substrate layer, the nickel-based intermediate layer and the aluminum-based surface layer reaches the set thickness.

[0064] The implementation schemes of this application will be described in detail below with reference to specific embodiments. However, those skilled in the art will understand that the following embodiments are only for illustrating this application and should not be regarded as limiting the scope of this application. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used without specified manufacturers are all conventional products that can be purchased commercially.

[0065] Example 1 Example 1 provides an abrasive sealing coating, the preparation method of which includes: S1. Pre-treat the metal substrate by sandblasting.

[0066] GH4169 high-temperature alloy substrate was selected and sandblasted with 80-mesh brown corundum sand at a pressure of 0.5 MPa. The distance between the sandblasting gun and the substrate surface was 120 mm, the spray angle was 75°, and the moving speed was 80 mm / s. After sandblasting, residual sand particles were blown away with 0.3 MPa compressed air. The roughness Ra of the metal substrate after treatment was 4.8 μm.

[0067] S2. Depositing a ceramic substrate layer on a metal substrate using a tri-anode plasma spraying process, specifically including the following steps: 8YSZ, NiCoCrAlY, ammonium bicarbonate, and graphene were mixed. NiCoCrAlY comprised 18 wt% Cr, 10 wt% Al, 12 wt% Co, 0.5 wt% Y, and the balance Ni. 8YSZ accounted for 70% of the total volume of the mixture, NiCoCrAlY accounted for 30%, graphene accounted for 1%, and ammonium bicarbonate accounted for 2 wt% of the total mass of the mixture.

[0068] Using a mixture of 8YSZ, NiCoCrAlY, graphene and ammonium bicarbonate as raw materials, a three-anode plasma spraying method was adopted, with a main arc power of 50kW, an auxiliary arc power of 15kW, and plasma gas flow rates of argon and hydrogen of 60L / min and 10L / min, respectively. The spraying distance was 120mm, the powder feeding rate was 25g / min, and the spraying was stopped after 10 sprayings when the thickness of the ceramic substrate layer was 225μm. After spraying, the coating is transferred to a vacuum annealing furnace at a vacuum degree of 5×10⁻⁶. -4 Under Pa conditions, the temperature is increased to 800℃ at 5℃ / min, held for 2 hours, and then cooled to below 100℃ before being removed from the furnace.

[0069] The ceramic substrate has a porosity of 25% and a hardness of 78 (HR45Y).

[0070] S3. Forming a nickel-based intermediate layer on a ceramic substrate using the HVOF process, specifically including the following steps: Using NiCrAlY powder (NiCrAlY includes 17wt% Cr, 10wt% Al, 0.5wt% Y and the balance Ni) as raw material, the first intermediate layer was sprayed in pulsed HVOF mode (pulse frequency 70Hz) first in high hardness mode. The specific parameters were: kerosene 18L / h, O2 flow rate 350L / min, powder feeding rate 28g / min. Spraying was stopped when the thickness of the first intermediate layer was 75μm. The hardness of the first intermediate layer HR45Y was 65 and the porosity was 8%.

[0071] Then, a second intermediate layer is sprayed on the first intermediate layer in a low-hardness mode. The specific parameters are: kerosene 18L / h, O2 flow rate 320L / min, powder feeding rate 22g / min. Spraying is stopped when the thickness of the second intermediate layer is 75μm. The HR45Y hardness of the second intermediate layer is 50 and the porosity is 12%.

[0072] The total thickness of the nickel-based interlayer is 150 μm.

[0073] S4. An aluminum-based surface layer is formed on the nickel-based intermediate layer using a cold spraying process, specifically including the following steps: Aluminum-silicon alloy powder is mixed with graphite powder, wherein the Si content in the aluminum-silicon alloy powder is 10wt%, and the volume of graphite powder accounts for 10% of the total volume of the aluminum-silicon alloy powder and graphite powder.

[0074] Using a mixture of aluminum-silicon alloy powder and graphite powder as raw material, a dual-powder-feeding cold spraying system was adopted. The working gas was nitrogen, with a pressure of 1.5 MPa and a temperature of 90℃. The powder feeding rate ratio of aluminum-silicon alloy powder to graphite powder was 7:1 (the powder feeding rate of aluminum-silicon alloy powder was 21 g / min, and the powder feeding rate of graphite powder was 3 g / min). The spraying distance was 25 mm, the nozzle moving speed was 100 mm / s, and the spraying was stopped after 6 sprays when the thickness reached 75 μm. A 75 μm thick aluminum-based surface layer was obtained. The HR45Y hardness of the aluminum-based surface layer was 45, and the porosity was 30%.

[0075] The thickness ratio of the aluminum-based surface layer to the nickel-based intermediate layer and the ceramic substrate layer is 1:2:3.

[0076] Example 2 The abrasive sealing coating was prepared according to the method of Example 1, with other parameters the same as in Example 1. The difference from Example 1 is as follows: In step S2, the raw materials for preparing the ceramic substrate layer are as follows: In Example 2, carbon nanotubes are used to replace graphene in Example 1. In Example 2, the volume of 8YSZ accounts for 60% of the total volume of 8YSZ and NiCoCrAlY, the volume of NiCoCrAlY accounts for 40% of the total volume of 8YSZ and NiCoCrAlY, and the volume of carbon nanotubes accounts for 0.8% of the total volume of 8YSZ and NiCoCrAlY.

[0077] The main arc power is 45kW and the auxiliary arc power is 12kW.

[0078] The ceramic substrate has a thickness of 180 μm, a porosity of 22%, and a hardness of 72 (HR45Y).

[0079] In step S3, the total thickness of the nickel-based interlayer is 140 μm, the thickness of the first interlayer is 70 μm, the hardness of HR45Y is 64, and the porosity is 7%. The thickness of the second interlayer is 70 μm, the hardness of HR45Y is 49, and the porosity is 11%.

[0080] In step S4, the volume of graphite powder in the raw materials for preparing the aluminum-based surface layer accounts for 5% of the total volume of aluminum-silicon alloy powder and graphite powder, and the Si content in the aluminum-silicon alloy powder is 8wt%.

[0081] The ratio of the feeding rate of aluminum-silicon alloy powder to graphite powder is 8:1.

[0082] The aluminum-based surface layer has a thickness of 55μm, a hardness of HR45Y of 42, and a porosity of 25%.

[0083] The thickness ratio of the aluminum-based surface layer to the nickel-based intermediate layer and the ceramic substrate layer is 1:2.5:3.3.

[0084] Example 3 The abrasive sealing coating was prepared according to the method of Example 1, with other parameters the same as in Example 1. The difference from Example 1 is as follows: In step S2, the raw materials used to prepare the ceramic substrate layer include: 8YSZ accounting for 80% of the total volume of 8YSZ and NiCoCrAlY, NiCoCrAlY accounting for 20% of the total volume of 8YSZ and NiCoCrAlY, and graphene accounting for 1.5% of the total volume of 8YSZ and NiCoCrAlY.

[0085] The main arc power is 55kW and the auxiliary arc power is 18kW.

[0086] The ceramic substrate has a thickness of 280 μm, a porosity of 28%, and a hardness of 82 for HR45Y.

[0087] In step S3, the total thickness of the nickel-based interlayer is 190 μm, the thickness of the first interlayer is 95 μm, the hardness of HR45Y is 66, and the porosity is 8%. The thickness of the second interlayer is 95 μm, the hardness of HR45Y is 51, and the porosity is 12%.

[0088] In step S4, the volume of graphite powder in the raw materials for preparing the aluminum-based surface layer accounts for 15% of the total volume of aluminum-silicon alloy powder and graphite powder, and the Si content in the aluminum-silicon alloy powder is 12wt%.

[0089] The ratio of the feeding rate of aluminum-silicon alloy powder to graphite powder is 5:1.

[0090] The aluminum-based surface layer has a thickness of 90μm, a hardness of HR45Y of 48, and a porosity of 35%.

[0091] The thickness ratio of the aluminum-based surface layer to the nickel-based intermediate layer and the ceramic substrate layer is 1:2.1:3.1.

[0092] Example 4 The abrasive sealing coating was prepared according to the method of Example 1, with other parameters the same as in Example 1. The difference from Example 1 is as follows: In step S2, the raw materials for preparing the ceramic substrate layer are as follows: In Example 4, carbon nanotubes are used to replace the graphene in Example 1. In Example 4, the volume of carbon nanotubes accounts for 0.5% of the total volume of 8YSZ and NiCoCrAlY.

[0093] The ceramic substrate has a thickness of 225 μm, a porosity of 25%, and a hardness of 76 (HR45Y).

[0094] Example 5 The abrasive sealing coating was prepared according to the method of Example 1, with other parameters the same as in Example 1. The difference from Example 1 is as follows: In step S2, the raw materials used to prepare the ceramic substrate layer include graphene, which accounts for 2% of the total volume of 8YSZ and NiCoCrAlY.

[0095] The ceramic substrate has a thickness of 225 μm, a porosity of 25%, and a hardness of 80 for HR45Y.

[0096] Comparative Example 1 The wearable sealing coating was prepared according to the method of Example 1, with other parameters the same as in Example 1. The difference from Example 1 is that step S4 was omitted and Comparative Example 1 did not have an aluminum-based surface layer.

[0097] Comparative Example 2 The wearable sealing coating was prepared according to the method of Example 1, with other parameters the same as in Example 1. The difference from Example 1 is that step S3 was omitted, and step S4 was performed directly after step S2. Comparative Example 2 did not have a nickel-based intermediate layer.

[0098] Comparative Example 3 The wearable sealing coating was prepared according to the method of Example 1, with other parameters the same as in Example 1. The difference from Example 1 is that step S2 was omitted, and step S3 was performed directly after step S1. Comparative Example 3 did not have a ceramic substrate layer.

[0099] Comparative Example 4 The wearable sealing coating was prepared according to the method of Example 1, with other parameters being the same as in Example 1. The difference from Example 1 is that the raw material for preparing the ceramic substrate is NiCoCrAlY.

[0100] Comparative Example 5 The wearable sealing coating was prepared according to the method of Example 1, with other parameters the same as in Example 1. The difference from Example 1 is that the raw material for preparing the ceramic substrate is 8YSZ.

[0101] The wearable sealing coatings prepared in the examples and comparative examples were subjected to performance tests under the same conditions. The performance test methods included: Room temperature hardness: The hardness of the wearable sealing coating prepared in the examples or comparative examples at room temperature was tested using a Rockwell hardness tester (model HR-150A), HR45Y with a load of 45kg. High temperature (1000℃) HR15Y hardness: The hardness of the wearable sealing coating prepared in the example or comparative example was tested at a high temperature of 1000℃ using a high temperature Rockwell hardness tester: HRN / T150 Rockwell hardness tester, HR15Y with a load of 15kg. Porosity: The coating cross-section was observed using a scanning electron microscope (SEM, model SU8010), with 5 fields of view (magnified 500 times) selected. The pore area ratio was calculated using Image-Pro Plus software, and the average value was taken. Wear rate test: A pin-disc wear tester (model HT-1000) was used, with GH4169 alloy pins (5mm in diameter) as the mating parts. Low temperature, medium temperature, and high temperature tests were conducted to measure the wear rate of the wear-resistant sealing coating prepared in the test examples or comparative examples at low temperature, medium temperature, and high temperature. The test conditions are as follows: Low temperature (25℃) wear rate: test temperature 25℃, load 5N, rotation speed 500r / min, wear time 1h; Medium-temperature (700℃) wear rate: test temperature 700℃, load 5N, rotation speed 500r / min, wear time 1h; High temperature (1000℃) wear rate: test temperature 1000℃, load 5N, rotation speed 500r / min, wear time 1h; Wear rate calculation formula: Wear rate = Wear mass loss / (Load × Sliding distance); Thermal stability (coating hardness retention rate after 100 thermal cycles): The samples were subjected to thermal cycling tests in a box furnace at 1000℃. A single cycle was defined as: heating to 1000℃ for 1 hour, holding at that temperature for 1 hour, and then air cooling to room temperature for 1 hour, for a total of 100 cycles. The hardness of the coating before and after the cycles was tested, and the hardness retention rate was calculated using the following formula: Retention rate (%) = (Hardness after cycling / Hardness before cycling) × 100.

[0102] Blade wear test: Simulating engine blade scraping conditions, a blade-coating friction tester was used. The blade material was TC4 titanium alloy, the scraping speed was 10m / s, the load was 3N, and the mass loss of the blade was tested after 1000 scraping cycles.

[0103] The test results of the examples and comparative examples are shown in Table 1.

[0104] Table 1 Performance Comparison of Examples and Comparative Examples

[0105] As can be seen from Table 1, the sealing coatings of Examples 1-5 have a low wear rate, a high hardness retention rate after 100 thermal cycles, and a low blade wear. The overall performance of Examples 1-5 is significantly better than that of Comparative Examples 1-5.

[0106] Specifically, the sealing coatings of Examples 1-5 exhibited a low-temperature abrasion rate of 0.8-1.1 mg / N•m, a medium-temperature abrasion rate of 0.9-1.1 mg / N•m, and a high-temperature abrasion rate of 1.2-1.4 mg / N•m, with blade wear ≤8 mg. This demonstrates that the sealing coatings of this application possess stable and controllable low abrasion rates at low, medium, and high temperatures. Furthermore, the sealing coatings of Examples 1-5 maintained a hardness retention rate of ≥88% after 100 thermal cycles, and showed no delamination or cracking after thermal cycling, indicating that the sealing coatings of Examples 1-5 possess the advantage of high stability.

[0107] The higher low-temperature wear rate and blade wear of Comparative Example 1 may be due to the absence of an aluminum-based surface layer in Comparative Example 1.

[0108] Comparative Example 2 exhibits a higher wear rate at medium temperatures and a lower hardness retention rate after thermal cycling. Furthermore, the coating of Comparative Example 2 cracks after thermal cycling, which may be due to the absence of a nickel-based interlayer in Comparative Example 2.

[0109] The high high-temperature wear rate of Comparative Example 3 may be due to the absence of a ceramic substrate layer in Comparative Example 3.

[0110] The lower hardness retention rate after thermal cycling in Comparative Example 4 is likely due to the fact that the ceramic substrate of Comparative Example 4 was prepared using only NiCoCrAlY as the raw material.

[0111] The blade wear of Comparative Example 5 is relatively high, which may be due to the fact that the raw material for preparing the ceramic substrate of Comparative Example 5 is only 8YSZ.

[0112] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0113] Furthermore, those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, in the foregoing claims, any of the claimed embodiments can be used in any combination. The information disclosed in this background section is intended only to enhance the understanding of the general background of this application and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

Claims

1. An abradable seal coat characterized by, The ceramic base layer, the nickel-based intermediate layer and the aluminum-based surface layer are arranged in a stack; The material forming the ceramic base layer comprises 8YSZ, NiCoCrAlY, a doping material and a pore-forming agent, the doping material comprising at least one of graphene and carbon nanotube; The material forming the nickel-based intermediate layer comprises NiCrAlY; The material forming the aluminum-based surface layer comprises an aluminum-silicon alloy and graphite.

2. The abradable seal coat of claim 1, wherein, The volume of the 8YSZ accounts for 60-80% of the total volume of the 8YSZ and the NiCoCrAlY, the volume of the doping material accounts for 0.5-2% of the total volume of the 8YSZ and the NiCoCrAlY, and the mass of the pore-forming agent accounts for 1-3wt% of the total mass of the 8YSZ and the NiCoCrAlY; The pore-forming agent comprises ammonium bicarbonate; The NiCoCrAlY comprises 15-25wt% of Cr, 5-15wt% of Al, 6-16wt% of Co, 0.1-1.0wt% of Y, and the balance of Ni; The NiCrAlY comprises 15-20wt% of Cr, 8-12wt% of Al, 0.3-0.8wt% of Y, and the balance of Ni; The volume of the graphite accounts for 5-15% of the total volume of the aluminum-silicon alloy and the graphite; The silicon content in the aluminum-silicon alloy is 8-12wt%.

3. The abradable seal coat of claim 1, wherein, The porosity of the ceramic base layer is 20-30%; The porosity of the nickel-based intermediate layer is 5-15%; The porosity of the aluminum-based surface layer is 20-40%.

4. The abradable seal coat of claim 1, wherein, The HR45Y hardness of the ceramic base layer is greater than the HR45Y hardness of the nickel-based intermediate layer, and the HR45Y hardness of the nickel-based intermediate layer is greater than the HR45Y hardness of the aluminum-based surface layer.

5. The abradable seal coat of claim 4, wherein, The HR45Y hardness of the ceramic base layer is 70-85; The nickel-based intermediate layer comprises a first intermediate layer and a second intermediate layer arranged in a stack, the first intermediate layer is located between the ceramic base layer and the second intermediate layer, the hardness of the first intermediate layer is greater than that of the second intermediate layer, the HR45Y hardness of the first intermediate layer is 55-66, and the HR45Y hardness of the second intermediate layer is 49-55; The HR45Y hardness of the aluminum-based surface layer is 40-50.

6. The abradable seal coat of claim 5, wherein, The thickness of the aluminum-based surface layer is 50-100μm, the thickness of the nickel-based intermediate layer is 100-200μm, and the thickness of the ceramic base layer is 150-300μm; And / or, the ratio of the thickness of the aluminum-based surface layer to the nickel-based intermediate layer and the ceramic base layer is 1:2:3 to 1:3:

5.

7. The abradable seal coat of claim 5 or 6, wherein, The ratio of the thickness of the first intermediate layer to the second intermediate layer is 1:(0.5-1.5).

8. A method of producing an abradable seal coat according to any one of claims 1 to 7, characterised in that, The method comprises: sandblasting pretreatment is performed on a metal substrate; a ceramic base layer is deposited on the pretreated metal substrate by adopting a three-anode plasma spraying process, using a mixture of 8YSZ, NiCoCrAlY, a doping material and a pore-forming agent as raw materials; a nickel-based intermediate layer is formed on the ceramic base layer by adopting a HVOF process, using a NiCrAlY powder as a spraying raw material; The aluminum-based surface layer is formed on the nickel-based intermediate layer by cold spraying process using a mixture of aluminum-silicon alloy and graphite as raw material.

9. The method of claim 8, wherein the abradable seal coating is prepared by, The surface roughness Ra of the pretreated metal substrate is 3.2-6.3 μm.

10. The method of making an abradable seal coat according to claim 8 or 9, characterized in that, The preparation method satisfies at least one of the following conditions: (1) The ceramic base layer is deposited on the pretreated metal substrate by three-anode plasma spraying process, which includes spraying on the pretreated metal substrate by three-anode plasma spraying process, and then transferring into a vacuum annealing furnace for annealing treatment; wherein the spraying parameters of spraying on the pretreated metal substrate by three-anode plasma spraying process include independently controlling the main arc power of 40-60 kW and the auxiliary arc power of 10-20 kW, the flow ratio of argon and hydrogen plasma gas being (4-8):1, the spraying distance being 100-150 mm, the powder feeding rate being 22-28 g / min, the spray gun moving speed being 75-85 mm / s, and the required thickness being achieved by controlling the spraying times; the annealing treatment includes heating at a rate of 3-7 ℃ / min to 780-820 ℃, and keeping at 780-820 ℃ for 1.5-2.5 h; (2) The nickel-based intermediate layer is formed on the ceramic base layer by HVOF process, which includes using pulse HVOF mode, pulse frequency of 50-100 Hz, and spraying to form a first intermediate layer under the following conditions: kerosene flow of 16-20 L / h, O2 flow of 340-360 L / min, and powder feeding rate of 26-30 g / min; and then spraying to form a second intermediate layer under the following conditions: kerosene flow of 16-20 L / h, O2 flow of 310-330 L / min, and powder feeding rate of 20-24 g / min; the coating thickness is controlled by adjusting the spraying times until the required thicknesses of the first intermediate layer and the second intermediate layer are achieved; (3) The aluminum-based surface layer is formed on the nickel-based intermediate layer by cold spraying process, which includes using a double-powder feeding cold spraying system, the working gas being nitrogen, the gas pressure being 1-2 MPa, the gas temperature being ≤100 ℃, the powder feeding rate ratio of aluminum-silicon alloy to graphite being 8:1 to 5:1, the total powder feeding rate being 21-25 g / min, the spraying distance being 20-30 mm, the nozzle moving speed being 90-110 mm / s, and the required thickness being achieved by adjusting the spraying times.

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