A turbine outer ring, its preparation method and application

Abstract

This invention discloses a turbine outer ring, its preparation method, and its application, belonging to the field of turbine outer ring technology. The turbine outer ring includes a turbine outer ring substrate and a CoNiCrAlY high-temperature protective coating disposed on the surface of the turbine outer ring substrate. This coating is prepared by laser-assisted cold gas dynamic spraying. The turbine outer ring substrate is composed of multiple independent sealing blocks spliced ​​together. The surface of each sealing block has a uniformly distributed micro-serrated structure. The CoNiCrAlY high-temperature protective coating includes a transition layer deposited with high laser power near the interface of the turbine outer ring substrate and a subsequent surface layer deposited with low laser power. The aforementioned turbine outer ring substrate and high-temperature protective coating exhibit long-lasting oxidation resistance, high-temperature resistance, and excellent bonding strength, effectively preventing wear and high-temperature corrosion of the turbine outer ring substrate, providing a reliable solution for the stable operation of the turbine outer ring.

Description

Technical Field

[0001] This invention relates to the field of turbine outer ring technology, and more specifically, to a turbine outer ring, its preparation method, and its application. Background Technology

[0002] The turbine outer ring, as a crucial hot-end component of aero-engine turbine seals, comes into direct contact with high-temperature exhaust gases and is an indispensable key component for improving engine thrust, efficiency, and reducing fuel consumption. To enhance the sealing and high-temperature protection performance of the turbine outer ring, vacuum plasma spraying is commonly used in practical engineering applications to prepare a sealing and protective coating with a thickness greater than 1.5 mm on the turbine outer ring surface. This improves the engine's boost ratio and turbine efficiency, and provides high-temperature corrosion protection for the turbine outer ring. However, this method is costly and inefficient, and the resulting coating has insufficient adhesion to the substrate, affecting the high-temperature friction and wear performance and thermal shock resistance of the turbine outer ring.

[0003] In view of this, the present invention is proposed. Summary of the Invention

[0004] The purpose of this invention is to provide a turbine outer ring, its preparation method, and its application, so as to solve or improve the above-mentioned technical problems.

[0005] This invention can be implemented as follows: In a first aspect, the present invention provides a turbine outer ring, the turbine outer ring comprising a turbine outer ring substrate and a CoNiCrAlY high-temperature protective coating disposed on the surface of the turbine outer ring substrate; The turbine outer ring matrix is ​​composed of multiple independent sealing blocks spliced ​​together; the surface of the sealing blocks has a uniformly distributed micro-serrated structure; The CoNiCrAlY high-temperature protective coating includes a transition layer formed by high-power deposition near the turbine outer ring substrate interface and a surface layer formed by low-power deposition on the surface of the transition layer; wherein the thickness and porosity of the transition layer are lower than those of the surface layer; there is no obvious delamination between the transition layer and the surface layer.

[0006] In an optional embodiment, the total thickness of the high-temperature protective coating is 1.5 mm to 2.0 mm; And / or, the thickness of the transition layer is 0.1 mm to 0.3 mm, and the porosity is ≤0.1%; And / or, the thickness of the surface layer is 1.2mm~1.9mm, and the porosity is ≤0.45%.

[0007] In an optional embodiment, the CoNiCrAlY powder used in the transition layer and the top layer has a particle size of 5μm to 80μm.

[0008] In an optional implementation, the micro-serrated structure is formed by removing localized substrate material using laser cleaning, with the removed area and the uncleaned area forming a micro-serrated structure.

[0009] In an optional implementation, the roughness of the micro-serrated structure is ≤8μm.

[0010] In an optional embodiment, the turbine outer ring also has at least one of the following features: Feature 1: The porosity of the CoNiCrAlY high-temperature protective coating does not exceed 0.45%; Feature 2: The bonding strength between the turbine outer ring substrate and the CoNiCrAlY high-temperature protective coating is not less than 64MPa; Feature 3: The wear amount of the CoNiCrAlY high-temperature protective coating does not exceed 0.0023g; Feature 4: The coefficient of friction of the CoNiCrAlY high-temperature protective coating does not exceed 0.3895; Feature 5: The CoNiCrAlY high-temperature protective coating has a shock resistance of no less than 100 cycles.

[0011] In a second aspect, the present invention provides a method for preparing a turbine outer ring as described in any of the foregoing embodiments, comprising the following steps: sequentially preparing a transition layer and a surface layer on the surface of a turbine outer ring substrate, followed by heat treatment.

[0012] In an optional embodiment, the turbine outer ring substrate is pretreated before the transition layer is prepared; Pretreatment includes machining, grinding, degreasing, and roughening of the sealing block surface in the turbine outer ring matrix.

[0013] In an optional implementation, laser cleaning is used to roughen the surface and form a micro-serrated structure.

[0014] In an optional embodiment, the conditions for laser cleaning include: laser power of 50W~200W; focal length of the laser source to the substrate surface of 50mm~100mm; angle between the laser source and the substrate surface of 30°~80°; and moving speed of the laser source of 50mm / s~100mm / s.

[0015] In an optional embodiment, the transition layer is prepared by high-power laser combined with cold gas dynamic spraying. In the laser-composite cold gas power spraying process, the turbine outer ring substrate is fixed on a rotatable three-jaw chuck; the laser and the cold gas power spraying gun are simultaneously integrated on the robotic arm to perform spraying in synchronous motion; The spraying conditions include: laser power of 6kW~10kW, focal length from the laser source to the substrate surface of 350mm~550mm, and angle between the laser source and the substrate surface of 30°~50°; compressed gas pressure of 4MPa~5.5MPa, and compressed gas temperature of 600℃~850℃; spraying distance of 20mm~50mm, spraying angle of 60°~90°, and powder feeding rate of 50g / min~60g / min; vertical movement speed of the robot arm of 5mm / s~10mm / s; and rotational speed of the three-jaw chuck of 50r / min~80r / min.

[0016] In an optional implementation, the compressed gas is nitrogen.

[0017] In an optional embodiment, the surface layer is prepared by a low-power laser-assisted cold gas spraying method; In the laser-composite cold gas power spraying process, the turbine outer ring substrate is fixed on a rotatable three-jaw chuck; the laser and the cold gas power spraying gun are simultaneously integrated on the robotic arm to perform spraying in synchronous motion.

[0018] The spraying conditions include: laser power of 1kW~4kW, focal length from the laser source to the substrate surface of 350mm~550mm; angle between the laser source and the substrate surface of 30°~50°; compressed gas pressure of 4MPa~5.5MPa, compressed gas temperature of 600℃~800℃; spraying distance of 20mm~50mm, spraying angle of 60°~90°; powder feeding rate of 100g / min~120g / min; vertical movement speed of the robot arm of 2mm / s~4mm / s; and rotational speed of the three-jaw chuck of 120r / min~180r / min.

[0019] In an optional implementation, the compressed gas is nitrogen.

[0020] In an optional embodiment, the heat treatment method is vacuum heat treatment; the temperature of vacuum heat treatment is 800℃~1100℃, and the time of vacuum heat treatment is 3h~5h.

[0021] Thirdly, the present invention provides an aircraft engine having a turbine outer ring according to any of the foregoing embodiments.

[0022] The beneficial effects of this invention include: The turbine outer ring provided by the present invention contains a CoNiCrAlY high-temperature protective coating that has long-lasting anti-oxidation and high-temperature resistance properties, and the turbine outer ring substrate and the high-temperature protective coating have excellent bonding strength.

[0023] This invention roughens the surface of the turbine outer ring substrate using laser cleaning before spraying, reducing the interface contamination rate and obtaining a specific micro-serrated structure, thus enhancing the adhesion between the coating and the substrate. Through laser-combined nitrogen-cooled gas spraying, a high-temperature protective coating with excellent bonding strength, long-lasting oxidation resistance, and high-temperature resistance is efficiently and cost-effectively prepared, effectively preventing wear and high-temperature corrosion of the turbine outer ring substrate and ensuring stable operation of the turbine outer ring. The turbine outer ring preparation method provided by this invention can be completed in one step, is simple to operate, and produces quickly. It eliminates the need for vacuum stress-relief heat treatment during coating deposition and the need for switching compressed gases, resulting in low cost, high efficiency, minimal equipment wear, and ease of large-scale production. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a photograph of the turbine outer ring in Example 1; Figure 2 This is a schematic diagram of the tooling fixture in Example 1; Figure 3 This is a photograph of the substrate surface roughening process performed using laser cleaning in Example 1; Figure 4 These are microscopic images of the interface of the high-temperature protective coating in Example 1 before and after heat treatment. Figure 5 These are photographs showing the tensile bonding strength results of the high-temperature protective coatings in Examples 1, 2, and 3. Figure 6 The results of high-temperature protective coatings of Example 1 and Comparative Example 1 after high-temperature friction and wear at 800°C are shown in the figure. Figure 7 The images show the results of the high-temperature protective coating in Example 1 after 10, 40, 70, and 100 thermal shock tests. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0027] The turbine outer ring, its preparation method, and its application provided by this invention will be described in detail below.

[0028] The present invention provides a turbine outer ring, which includes a turbine outer ring substrate and a CoNiCrAlY high-temperature protective coating disposed on the surface of the turbine outer ring substrate.

[0029] The aforementioned turbine outer ring substrate is composed of multiple independent sealing blocks. Since the turbine outer ring is exposed to high-temperature combustion gases, but the temperature distribution is uneven, the use of multiple independent sealing blocks allows each block to expand independently, reducing thermal stress accumulation and preventing overall structural failure due to mismatched thermal expansion. Furthermore, during operation, friction occurs between the turbine blade tips and the outer ring. The multiple independent sealing blocks allow for individual replacement after localized wear, preventing complete scrapping. This eliminates the need to disassemble the entire turbine component during maintenance; only the damaged sealing blocks are replaced, significantly reducing maintenance costs and downtime.

[0030] In this invention, the surface of the sealing block has a uniformly distributed micro-serrated structure.

[0031] In some optional embodiments, the micro-serrated structure utilizes laser cleaning to locally remove the substrate material, forming a micro-serrated structure between the removed area and the uncleaned area. In some optional embodiments, the roughness of the micro-serrated structure is ≤8μm.

[0032] The CoNiCrAlY high-temperature protective coating comprises a high-power deposition transition layer near the turbine outer ring substrate interface and a subsequent low-power deposition top layer. This high-temperature protective coating exhibits excellent high-temperature phase stability, effectively isolating high-temperature combustion gases and reducing the substrate operating temperature. This coating system significantly enhances the turbine outer ring's resistance to oxidation and frictional wear under high-temperature, high-speed combustion gas scouring environments.

[0033] It should be noted that the coefficients of thermal expansion of the CoNiCrAlY coating and the nickel-based superalloy substrate are not matched. In order to ensure the formation of a strong metallurgical bond, this invention sets a transition layer and a surface layer in sequence, which enables the high-temperature protective coating and the nickel-based superalloy substrate to achieve reliable matching and long-term protection under high temperature and high stress environment.

[0034] The transition layer requires high laser power to allow the powder particles to absorb a lot of heat and soften, achieving strong heterogeneous interfacial bonding and low porosity with the nickel-based superalloy matrix. The surface layer is a deposition of the same powder, and a lower laser power is sufficient to achieve strong bonding of powder particles in the homogeneous transition layer, but the porosity is slightly higher.

[0035] In this invention, the thickness and porosity of the transition layer are lower than those of the surface layer; and there is no obvious delamination between the transition layer and the surface layer.

[0036] In some alternative implementations, the total thickness of the high-temperature protective coating can be 1.5mm to 2.0mm, such as 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm or 2mm, or other values ​​within the range of 1.5mm to 2.0mm.

[0037] The thickness of the transition layer can be 0.1mm to 0.3mm, such as 0.1mm, 0.15mm, 0.2mm, 0.25mm, or 0.3mm, or other values ​​within the range of 0.1mm to 0.3mm. If the thickness of the transition layer is less than 0.1mm, it is difficult to achieve metallurgical bonding between CoNiCrAlY and the nickel-based superalloy substrate, resulting in poor bonding at the heterogeneous interface and easy coating peeling. If the thickness of the transition layer is greater than 0.3mm, the large heat input can easily lead to cracking at the coating / substrate interface.

[0038] The thickness of the surface layer can be 1.2mm to 1.9mm, such as 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm or 1.9mm, or other values ​​within the range of 1.2mm to 1.9mm.

[0039] In some optional embodiments, the CoNiCrAlY powder used in the transition layer and the top layer has a particle size of 5μm to 80μm, preferably spherical powder. By using CoNiCrAlY powder as the raw material for preparing the high-temperature protective coating, this invention enables the high-temperature protective coating to possess excellent oxidation resistance and thermal shock resistance.

[0040] In some alternative embodiments, the porosity of the transition layer is ≤0.1%, such as 0.03% to 0.06%; the porosity of the surface layer is ≤0.45%, such as 0.28% to 0.45%.

[0041] In some alternative embodiments, the porosity of the CoNiCrAlY high-temperature protective coating does not exceed 0.45%, such as 0.32% to 0.44%.

[0042] In some optional embodiments, the bonding strength between the turbine outer ring substrate and the CoNiCrAlY high-temperature protective coating is not less than 64 MPa, such as 67 MPa to 81 MPa.

[0043] In some alternative implementations, the wear amount of the CoNiCrAlY high-temperature protective coating does not exceed 0.0023g, such as 0.0021~0.0023g.

[0044] In some alternative implementations, the coefficient of friction of the CoNiCrAlY high-temperature protective coating does not exceed 0.3895, such as 0.3423~0.3895.

[0045] In some optional implementations, the CoNiCrAlY high-temperature protective coating has a shock resistance of not less than 100 cycles.

[0046] Accordingly, the present invention also provides a method for preparing the above-mentioned turbine outer ring, comprising the following steps: sequentially preparing a transition layer and a surface layer on the surface of the turbine outer ring substrate, followed by heat treatment.

[0047] In some alternative implementations, the turbine outer ring substrate is pretreated before the transition layer is prepared.

[0048] Pretreatment may include machining, grinding, degreasing, and roughening the surface of the sealing block in the turbine outer ring matrix. For example, the sealing block of the turbine outer ring can be fixed to a designed and manufactured tooling fixture with screws, and the fixture can be fixed to a rotatable three-jaw chuck; the surface of the fixed sealing block of the turbine outer ring is machined, ground, and degreased, and then roughened by laser cleaning to give the sealing block surface of the turbine outer ring a uniformly distributed micro-serrated structure.

[0049] Damaged coatings on the sealing block surface can be removed through lathe machining and grinding to prevent them from affecting subsequent coating deposition. Since the turbine outer ring sealing block may become contaminated with grease or other organic pollutants during production, transportation, or storage, these pollutants can reduce the adhesion between the coating and the substrate. Therefore, this invention utilizes organic solvents (such as acetone, alcohol, etc.) for cleaning or soaking in alkaline degreasing agents to remove surface grease and dirt, ensuring a clean and uncontaminated substrate surface. Laser cleaning roughens the surface, improving coating adhesion.

[0050] In some optional embodiments, when laser cleaning is used for roughening to form a micro-serrated structure, the conditions for laser cleaning may include: a laser power of 50W to 200W (e.g., 50W, 80W, 100W, 150W, or 200W); a focal length of 50mm to 100mm from the laser source to the substrate surface (e.g., 50mm, 60mm, 70mm, 80mm, 90mm, or 100mm); an angle of 30° to 80° between the laser source and the substrate surface (e.g., 30°, 40°, 50°, 60°, 70°, or 80°); and a moving speed of 50mm / s to 100mm / s (e.g., 50mm / s, 60mm / s, 75mm / s, 80mm / s, 90mm / s, or 100mm / s).

[0051] The laser power mentioned above is set based on the specific particle size range of the CoNiCrAlY powder used in this invention and the characteristics of the nickel-based superalloy matrix material. Laser power within this range helps to reduce the impact of heat output on the matrix, preventing matrix deformation, and also contributes to surface roughening. Simultaneously, when using laser for surface roughening, controlling the distance from the laser source to the matrix surface between 50mm and 100mm ensures a suitable energy density. An angle greater than 80° between the laser source and the matrix surface increases the risk of reflection; an angle less than 30° reduces the effective energy. There is a synergistic matching relationship between the laser cleaning parameters and the size of the resulting micro-serrated structure.

[0052] in, This represents the net energy required per unit area to remove the material. This is expressed as a coefficient related to the absorption characteristics of the material (CoNiCrAlY / matrix) for a specific wavelength of laser light. Indicates laser power. This indicates the angle between the laser source and the substrate surface. Indicates the moving speed of the laser light source. This represents the focal length from the laser source to the substrate surface. The pit depth and net energy... They are positively correlated.

[0053] It should be noted that existing technologies typically employ grinding or sandblasting to pre-treat the substrate surface, which results in poor adhesion between the coating and the substrate and severe interface contamination. This invention uses laser cleaning to roughen the substrate surface, effectively reducing interface contamination while maintaining adhesion. This prevents coating cracking or peeling under intense thermal stress from alternating hot and cold cycles, thus avoiding major engine malfunctions and providing ideal adhesion conditions for the coating.

[0054] In some alternative implementations, the CoNiCrAlY transition layer can be prepared by high-power laser-assisted cold gas spraying.

[0055] In the aforementioned laser-composite cold gas power spraying process, the turbine outer ring substrate can be fixed on a rotatable three-jaw chuck; the laser and the cold gas power spraying gun are simultaneously integrated on the robotic arm to perform spraying in synchronous motion (the laser and the spray gun perform spraying in synchronous motion).

[0056] Spraying conditions may include: laser power of 6kW~10kW (e.g., 6kW, 7kW, 8kW, 9kW, or 10kW), focal length from the laser source to the substrate surface of 350mm~550mm (e.g., 350mm, 400mm, 450mm, 500mm, or 550mm), angle between the laser source and the substrate surface of 30°~50° (e.g., 30°, 35°, 40°, 45°, or 50°), compressed gas pressure of 4MPa~5.5MPa (e.g., 4MPa, 4.5MPa, 5MPa, or 5.5MPa), and compressed gas temperature of 600℃~850℃ (e.g., 600℃, 650℃, 700℃, 750℃, 800℃, or 850℃). The spraying distance is 20mm~50mm (e.g., 20mm, 30mm, 40mm, or 50mm), the spraying angle is 60°~90° (e.g., 60°, 70°, 80°, or 90°), and the powder feeding rate is 50g / min~60g / min (e.g., 50g / min, 55g / min, or 60g / min). The vertical movement speed of the robotic arm is 5mm / s~10mm / s (e.g., 5mm / s, 6mm / s, 7mm / s, 8mm / s, 9mm / s, or 10mm / s). The rotational speed of the three-jaw chuck is 50r / min~80r / min (e.g., 50r / min, 60r / min, 70r / min, or 80r / min). The compressed gas mentioned above can be nitrogen.

[0057] In the aforementioned spraying process, the cold-air powered spray gun heats compressed nitrogen gas through a heater, creating a high-temperature supersonic airflow. This airflow propels the CoNiCrAlY powder material through a Laval nozzle, causing it to impact the substrate surface and undergo plastic deformation, thus depositing the powder. By using high-power laser parameters and combining these conditions, a highly adhesive transition layer is formed on the surface of the sealing block.

[0058] Specifically, if the laser power is below 6kW, the CoNiCrAlY powder particles are prone to insufficient deformation on the nickel-based superalloy substrate surface, resulting in poor bonding and coating detachment. If the laser power is above 10kW, the high heat input can cause interface cracking. If the powder feed rate is less than 50g / min, the single-layer coating thickness is low, requiring multi-layer deposition, which easily leads to coating interface separation and poor coating bonding. If the powder feed rate is greater than 60g / min, the coating cross-section of a single pass is prone to triangular distribution, and the overlap between passes generates high porosity. If the vertical movement speed of the robot arm is less than 5mm / s or the rotation speed of the three-jaw chuck is less than 50r / min, high heat input and thermal stress are likely to occur, making the coating prone to cracking. If the vertical movement speed of the robot arm is greater than 10mm / s or the rotation speed of the three-jaw chuck is greater than 80r / min, the low heat input is insufficient to achieve metallurgical bonding between the coating and the substrate, making the coating prone to detachment.

[0059] In some alternative implementations, the surface layer can be prepared by low-power laser-assisted cold gas spraying.

[0060] Similarly, in the above-mentioned laser-composite cold gas power spraying process, the turbine outer ring substrate can be fixed on a rotatable three-jaw chuck; the laser and the cold gas power spraying gun are simultaneously integrated on the robotic arm to perform spraying in synchronous motion.

[0061] Spraying conditions may include: laser power of 1kW~4kW (e.g., 1kW, 2kW, 3kW, or 4kW); focal length from the laser source to the substrate surface of 350mm~550mm (e.g., 350mm, 400mm, 450mm, 500mm, or 550mm); angle between the laser source and the substrate surface of 30°~50° (e.g., 30°, 35°, 40°, 45°, or 50°); compressed gas pressure of 4MPa~5.5MPa (e.g., 4MPa, 4.5MPa, 5MPa, or 5.5MPa); and compressed gas temperature of 600℃~800℃ (e.g., 600℃, 650℃, 700℃, 750℃, or 80℃). The spraying temperature is 0℃, etc.; the spraying distance is 20mm~50mm (e.g., 20mm, 30mm, 40mm or 50mm, etc.); the spraying angle is 60°~90° (e.g., 60°, 70°, 80° or 90°, etc.); the powder feeding rate is 100g / min~120g / min (e.g., 100g / min, 110g / min or 120g / min, etc.); the vertical movement speed of the robot arm is 2mm / s~4mm / s (e.g., 2mm / s, 3mm / s or 4mm / s, etc.); the rotational speed of the three-jaw chuck is 120r / min~180r / min (e.g., 120r / min, 150r / min or 180r / min, etc.). The compressed gas mentioned above can be nitrogen.

[0062] The surface layer prepared under the above conditions has good tribological properties.

[0063] Specifically, if the laser power is below 1kW, the CoNiCrAlY powder particles are not sufficiently deformed, resulting in abnormally high coating porosity and poor bonding. If the laser power is above 4kW, the high heat input can cause internal cracks in the coating. If the powder feed rate is less than 100g / min, the single-layer coating thickness is low, requiring multi-layer deposition, which easily leads to coating interface separation and poor coating bonding. If the powder feed rate is greater than 120g / min, the coating cross-section of a single pass is easily triangularly distributed, and the overlap between passes results in high porosity. If the vertical movement speed of the robot arm is less than 2mm / s or the rotation speed of the three-jaw chuck is less than 120r / min, high heat input and thermal stress are easily generated, making the coating prone to cracking. If the vertical movement speed of the robot arm is greater than 4mm / s or the rotation speed of the three-jaw chuck is greater than 180r / min, the low heat input is insufficient to achieve metallurgical bonding between the coating and the substrate, making the coating prone to peeling off.

[0064] In some alternative implementations, the spraying process is carried out in a one-time spraying manner, that is, the sealing block of the turbine outer ring is not removed, reinstalled or heat-treated during the entire spraying process, but is continued until the coating thickness reaches the required coating thickness.

[0065] Specifically, during the one-time spraying process, the tooling fixture holding the sealing block is fixed on a three-jaw chuck. After power is applied, when spraying the transition layer, the rotation speed of the three-jaw chuck is 50 r / min to 80 r / min, and the robotic arm holds the spray gun and performs reciprocating motion in the vertical direction at a speed of 5 mm / s to 10 mm / s. After the transition layer is prepared, the process parameters are adjusted to perform the topcoat spraying. The rotation speed of the three-jaw chuck is 120 r / min to 180 r / min, and the robotic arm holds the spray gun and performs reciprocating motion in the vertical direction at a speed of 2 mm / s to 4 mm / s, thus preparing a high-temperature protective coating with a thickness of 1.5 mm to 2.0 mm.

[0066] In some alternative embodiments, the heat treatment method can be vacuum heat treatment. The temperature of vacuum heat treatment can be 800℃~1100℃ (e.g., 800℃, 900℃, 1000℃ or 1100℃), and the time of vacuum heat treatment can be 3h~5h (e.g., 3h, 4h or 5h).

[0067] Specifically, compressed air is used to remove loosely bonded and poorly deformed powder particles adhering to the surface of the sealing block with the high-temperature protective coating. The sealing block is then placed stably in the uniform temperature zone of the furnace to ensure even heat transfer and prevent damage to the coating due to its own weight or contact with the surface at high temperatures. After closing the furnace door, the vacuum system is activated to evacuate the furnace pressure to ≤1×10⁻⁶. -2A high vacuum state of Pa is maintained to absolutely prevent oxidation of the coating and substrate at high temperatures. By adopting the above heat treatment conditions, excellent thermal shock resistance can be obtained.

[0068] If the vacuum heat treatment temperature is below 800℃ or the time is less than 3 hours, it is easy to cause insufficient heat treatment, resulting in an excessively thin or non-existent interdiffusion zone at the interface, which is not conducive to the formation of a strong metallurgical bond and may affect the thermal shock resistance and long-term bonding strength of the coating. If the vacuum heat treatment temperature is above 1100℃ or the time is longer than 5 hours, it is easy to cause excessive diffusion of Al elements from the coating to the substrate, which will cause a sharp decline in the coating's oxidation resistance, and the grains and precipitates inside the coating will be significantly coarsened, thereby reducing the creep strength and toughness of the coating.

[0069] Building upon the above, this invention roughens the surface of the turbine outer ring substrate using laser cleaning before spraying, reducing the interface contamination rate and enhancing the adhesion between the coating and the substrate. Furthermore, through a laser-composite nitrogen-cooled gas-powered spraying process, a CoNiCrAlY coating with excellent bonding strength, long-lasting oxidation resistance, and high-temperature resistance is efficiently and cost-effectively prepared. This effectively prevents wear and high-temperature corrosion of the turbine outer ring substrate, providing a reliable solution for the stable operation of the turbine outer ring. The preparation method provided by this invention can be achieved in one step, is simple to operate, and produces quickly. It eliminates the need for vacuum stress-relief heat treatment during coating deposition and the need for switching compressed gases, resulting in low cost, high efficiency, minimal equipment wear, and ease of large-scale production.

[0070] In addition, the present invention also provides an aircraft engine having the aforementioned turbine outer ring.

[0071] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0072] Example 1 This embodiment provides a turbine outer ring (such as...). Figure 1 As shown, it includes a turbine outer ring substrate and a high-temperature protective coating disposed on the surface of the turbine outer ring substrate. The turbine outer ring substrate is composed of 12 independent sealing blocks spliced ​​together; the surface of the sealing blocks has a uniformly distributed micro-serrated structure. The CoNiCrAlY high-temperature protective coating includes a high-power deposition transition layer near the interface of the turbine outer ring substrate and a subsequent low-power deposition surface layer; wherein, the CoNiCrAlY transition layer has a thickness of 0.1 mm and a porosity of 0.03%; the CoNiCrAlY surface layer has a thickness of 1.6 mm and a porosity of 0.32%.

[0073] The fabrication of the aforementioned turbine outer ring includes: S1: Pre-treatment of the turbine outer ring substrate.

[0074] The sealing block of the turbine outer ring is fixed to the tooling fixture (e.g., screws) Figure 2 As shown, the fixture is fixed on a rotatable three-jaw chuck; then, the surface of the sealing block of the fixed turbine outer ring is machined on a lathe and ground with a grinding wheel to remove the damaged coating on the surface of the sealing block. Subsequently, the surface is roughened by laser cleaning (as shown). Figure 3 As shown in the figure, the sealing block surface of the turbine outer ring has a uniformly distributed micro-serrated structure. During laser cleaning, the laser power is 50W, the focal length from the laser source to the substrate surface is 65mm, the angle between the laser source and the substrate surface is 70°, and the moving speed of the laser source is 50mm / s.

[0075] S2: Prepare the CoNiCrAlY transition layer.

[0076] A CoNiCrAlY transition layer was prepared using a high-power laser-assisted cold gas spraying method. In this process, the turbine outer ring substrate was fixed to a rotatable three-jaw chuck, and the laser and the cold gas spraying gun were simultaneously integrated onto a 6-axis industrial robot for synchronous spraying. The transition layer spraying parameters were as follows: laser power 8kW, focal length from the laser source to the substrate surface 400mm, angle between the laser source and the substrate surface 30°; compressed gas (nitrogen) pressure 5MPa, compressed gas temperature 850℃; spraying distance 30mm; spraying angle 90°; powder feed rate 50g / min; vertical movement speed of the 6-axis industrial robot 5mm / s; and rotational speed of the three-jaw chuck 80r / min.

[0077] S3: Prepare the CoNiCrAlY surface layer.

[0078] A CoNiCrAlY surface layer was prepared using a low-power laser-assisted cold gas spraying method. In this process, the turbine outer ring substrate was fixed to a rotatable three-jaw chuck, and the laser and the cold gas spraying gun were simultaneously integrated onto a 6-axis industrial robot for synchronous spraying. The surface layer spraying parameters were as follows: laser power 2.5kW; focal length from the laser source to the substrate surface 400mm; angle between the laser source and the substrate surface 30°; compressed gas (nitrogen) pressure 5.0MPa; compressed gas temperature 800℃; spraying distance 30mm; spraying angle 90°; powder feed rate 120g / min; vertical movement speed of the 6-axis industrial robot 2mm / s; and rotational speed of the three-jaw chuck 180r / min.

[0079] S4: Heat treatment.

[0080] Finally, the prepared coating was subjected to vacuum heat treatment at 1000℃ for 4 hours in a vacuum furnace.

[0081] Example 2 The difference between this embodiment and embodiment 1 is that in S1, during laser cleaning, the laser power is 80W, the focal length from the laser source to the substrate surface is 50mm, the angle between the laser source and the substrate surface is 60°, and the moving speed of the laser source is 70mm / s.

[0082] Example 3 The difference between this embodiment and embodiment 1 is that in S2, the laser power is 6kW, the focal length from the laser source to the substrate surface is 350mm, and the angle between the laser source and the substrate surface is 40°.

[0083] Example 4 The difference between this embodiment and embodiment 1 is that in S2, the powder feeding rate is 55g / min; and the rotation speed of the three-jaw chuck is 73r / min.

[0084] Example 5 The difference between this embodiment and embodiment 1 is that in S3, the laser power is 4kW.

[0085] Example 6 The difference between this embodiment and embodiment 1 is that in S3, the vertical movement speed of the 6-axis industrial robot is 3 mm / s; the rotational speed of the three-jaw chuck is 120 r / min.

[0086] Example 7 The difference between this embodiment and embodiment 1 is that in S4, the vacuum heat treatment time is 5 hours.

[0087] Example 8 This embodiment provides a turbine outer ring, which includes a turbine outer ring substrate and a high-temperature protective coating disposed on the surface of the turbine outer ring substrate. The turbine outer ring substrate is composed of 12 independent sealing blocks spliced ​​together; the surface of the sealing blocks has a uniformly distributed micro-serrated structure. The CoNiCrAlY high-temperature protective coating includes a high-power deposition transition layer near the interface of the turbine outer ring substrate and a subsequent low-power deposition surface layer; wherein, the CoNiCrAlY transition layer has a thickness of 0.1 mm and a porosity of 0.03%; the CoNiCrAlY surface layer has a thickness of 1.9 mm and a porosity of 0.45%.

[0088] The fabrication of the aforementioned turbine outer ring includes: S1: Pre-treatment of the turbine outer ring substrate.

[0089] The sealing block of the turbine outer ring is fixed to a tooling fixture with screws, and the fixture is fixed to a rotatable three-jaw chuck. Next, the surface of the fixed sealing block is machined on a lathe and ground with a grinding wheel to remove the damaged coating. Then, laser cleaning is used to roughen the surface, giving the sealing block a uniformly distributed micro-serrated structure. During laser cleaning, the laser power is 100W, the focal length from the laser source to the substrate surface is 75mm, the angle between the laser source and the substrate surface is 30°, and the laser source moving speed is 65mm / s.

[0090] S2: Prepare the CoNiCrAlY transition layer.

[0091] A CoNiCrAlY transition layer was prepared using a high-power laser-assisted cold gas spraying method. In this process, the turbine outer ring substrate was fixed to a rotatable three-jaw chuck, and the laser and the cold gas spraying gun were simultaneously integrated onto a 6-axis industrial robot for synchronous spraying. The transition layer spraying parameters were as follows: laser power 10kW, focal length from the laser source to the substrate surface 350mm, angle between the laser source and the substrate surface 40°; compressed gas (nitrogen) pressure 4MPa, compressed gas temperature 600℃; spraying distance 20mm; spraying angle 60°; powder feed rate 55g / min; vertical movement speed of the 6-axis industrial robot 8mm / s; and rotational speed of the three-jaw chuck 50r / min.

[0092] S3: Prepare the CoNiCrAlY surface layer.

[0093] A CoNiCrAlY surface layer was prepared using a low-power laser-assisted cold gas spraying method. In this process, the turbine outer ring substrate was fixed to a rotatable three-jaw chuck, and the laser and the cold gas spraying gun were simultaneously integrated onto a 6-axis industrial robot for synchronous spraying. The surface layer spraying parameters were as follows: laser power 1kW; focal length from the laser source to the substrate surface 350mm; angle between the laser source and the substrate surface 40°; compressed gas (nitrogen) pressure 4MPa; compressed gas temperature 600℃; spraying distance 20mm; spraying angle 60°; powder feed rate 100g / min; vertical movement speed of the 6-axis industrial robot 3mm / s; and rotational speed of the three-jaw chuck 140r / min.

[0094] S4: Heat treatment.

[0095] Finally, the prepared coating was subjected to vacuum heat treatment at 800°C for 5 hours in a vacuum furnace.

[0096] Example 9 This embodiment provides a turbine outer ring, which includes a turbine outer ring substrate and a high-temperature protective coating disposed on the surface of the turbine outer ring substrate. The turbine outer ring substrate is composed of 12 independent sealing blocks spliced ​​together; the surface of the sealing blocks has a uniformly distributed micro-serrated structure. The CoNiCrAlY high-temperature protective coating includes a high-power deposition transition layer near the interface of the turbine outer ring substrate and a subsequent low-power deposition surface layer; wherein, the CoNiCrAlY transition layer has a thickness of 0.3 mm and a porosity of 0.06%; the CoNiCrAlY surface layer has a thickness of 1.2 mm and a porosity of 0.28%.

[0097] The fabrication of the aforementioned turbine outer ring includes: S1: Pre-treatment of the turbine outer ring substrate.

[0098] The sealing block of the turbine outer ring is fixed to a tooling fixture with screws, and the fixture is fixed to a rotatable three-jaw chuck. Next, the surface of the fixed sealing block is machined on a lathe and ground with a grinding wheel to remove the damaged coating. Then, laser cleaning is used to roughen the surface, giving the sealing block a uniformly distributed micro-serrated structure. During laser cleaning, the laser power is 200W, the focal length from the laser source to the substrate surface is 100mm, the angle between the laser source and the substrate surface is 80°, and the laser source moving speed is 50mm / s.

[0099] S2: Prepare the CoNiCrAlY transition layer.

[0100] A CoNiCrAlY transition layer was prepared using a high-power laser-assisted cold gas spraying method. In this process, the turbine outer ring substrate was fixed to a rotatable three-jaw chuck, and the laser and the cold gas spraying gun were simultaneously integrated onto a 6-axis industrial robot for synchronous spraying. The transition layer spraying parameters were as follows: laser power 8kW, focal length from the laser source to the substrate surface 550mm, angle between the laser source and the substrate surface 50°; compressed gas (nitrogen) pressure 5.5MPa, compressed gas temperature 700℃; spraying distance 50mm; spraying angle 80°; powder feed rate 60g / min; vertical movement speed of the 6-axis industrial robot 10mm / s; and rotational speed of the three-jaw chuck 65r / min.

[0101] S3: Prepare the CoNiCrAlY surface layer.

[0102] A CoNiCrAlY surface layer was prepared using a low-power laser-assisted cold gas spraying method. In this process, the turbine outer ring substrate was fixed to a rotatable three-jaw chuck, and the laser and the cold gas spraying gun were simultaneously integrated onto a 6-axis industrial robot for synchronous spraying. The surface layer spraying parameters were as follows: laser power 2kW; focal length from the laser source to the substrate surface 550mm; angle between the laser source and the substrate surface 50°; compressed gas (nitrogen) pressure 5.5MPa; compressed gas temperature 700℃; spraying distance 50mm; spraying angle 80°; powder feed rate 110g / min; vertical movement speed of the 6-axis industrial robot 4mm / s; and rotational speed of the three-jaw chuck 160r / min.

[0103] S4: Heat treatment.

[0104] Finally, the prepared coating was subjected to vacuum heat treatment at 1100℃ for 3 hours in a vacuum furnace.

[0105] Comparative Example 1 The difference between this comparative example and Example 1 is that the entire high-temperature protective coating was prepared by nitrogen cold gas dynamic spraying. The specific spraying conditions were as follows: the compressed gas (nitrogen) pressure was 5.0 MPa, the compressed gas temperature was 800℃, the spraying distance was 30 mm, the spraying angle was 90°, the powder feeding rate was 120 g / min, the vertical movement speed of the 6-axis industrial robot was 2 mm / s, and the rotation speed of the three-jaw chuck was 180 r / min.

[0106] Comparative Example 2 The difference between this comparative example and Example 1 is that S1 was not roughened.

[0107] Comparative Example 3 The difference between this comparative example and Example 1 is that in S1, surface roughening treatment is performed by sandblasting, the type of alumina is alumina, the particle size of the alumina is 120 mesh, the sandblasting pressure is 0.4 MPa, and the sandblasting angle is 90°.

[0108] Comparative Example 4 The difference between this comparative example and Example 1 is that in S1, the surface is roughened by mechanical grinding, and a Bosch GWS6-125 angle grinder equipped with an 80-grit louvered grinding disc is used to perform uniform surface grinding.

[0109] Comparative Example 5 The difference between this comparative example and Example 1 is that in S1, the surface is roughened by sanding with 500 grit sandpaper.

[0110] Comparative Example 6 The difference between this comparative example and Example 1 is that in S1, surface roughening treatment is performed by water blasting, the blasting angle is 45°, the blasting pressure is 0.4MPa, and the blasting distance is 100mm.

[0111] Comparative Example 7 The difference between this comparative example and Example 1 is that in S2, the laser power is 2.5kW.

[0112] Comparative Example 8 The difference between this comparative example and Example 1 is that in S2, the laser power is 12kW.

[0113] Comparative Example 9 The difference between this comparative example and Example 1 is that in S2, the powder feeding rate is 40 g / min.

[0114] Comparative Example 10 The difference between this comparative example and Example 1 is that in S2, the powder feeding rate is 70 g / min.

[0115] Comparative Example 11 The difference between this comparative example and Example 1 is that in S2, the robot arm moves at a vertical speed of 4 mm / s.

[0116] Comparative Example 12 The difference between this comparative example and Example 1 is that in S2, the robot arm moves at a vertical speed of 12 mm / s.

[0117] Comparative Example 13 The difference between this comparative example and Example 1 is that in S2, the rotational speed of the three-jaw chuck is 40 r / min.

[0118] Comparative Example 14 The difference between this comparative example and Example 1 is that in S2, the rotational speed of the three-jaw chuck is 90 r / min.

[0119] Comparative Example 15 The difference between this comparative example and Example 1 is that in S3, the laser power is 0.5kW.

[0120] Comparative Example 16 The difference between this comparative example and Example 1 is that in S3, the laser power is 5kW.

[0121] Comparative Example 17 The difference between this comparative example and Example 1 is that in S4, the heat treatment temperature is 700°C.

[0122] Comparative Example 18 The difference between this comparative example and Example 1 is that in S4, the heat treatment temperature is 1200°C.

[0123] Test case The high-temperature protective coatings prepared in Examples 1-9 and Comparative Examples 1-18 were subjected to performance tests, including coating porosity, bonding strength, high-temperature tribological properties, and thermal shock resistance. The results are shown in Table 1 and... Figures 4 to 7 As shown.

[0124] Among them, porosity was characterized by optical microscopy (GB / T 3489); bonding strength was characterized by standard tensile testing (ASTM C633); high-temperature tribological properties were measured by ball-on-disk rotary friction (friction ball material WC, diameter 6 mm, pressure 5 N) (GB / T 43853); and thermal shock resistance was characterized by high-temperature thermal shock testing of the coating (ISO 14188:2012).

[0125] Table 1 Test Results

[0126] As can be seen from Examples 1-9 above, laser-composite cold gas dynamic spraying exhibits excellent comprehensive performance in the application of preparing high-temperature protective coatings on turbine outer rings. Among them, Example 1 shows the best comprehensive effect. The high-temperature alloy coating prepared in this example can simultaneously meet the requirements of low porosity, high bonding, good high-temperature friction and wear performance, and excellent thermal shock resistance, and can also significantly reduce costs.

[0127] A comparison of Example 1 and Comparative Example 1 shows that the coating prepared by laser-composite nitrogen-cooled gas dynamic spraying exhibits superior protective performance. The high-temperature protective coating prepared in Example 1 has low porosity, high bonding strength, and good high-temperature wear resistance; after 100 high-temperature thermal shock tests, the coating still showed no cracking or peeling (bonding strength...). Figures 4 to 7 In contrast, the high-temperature protective coating prepared in Comparative Example 1 had high porosity and interfacial fracture, and cracked after 40 high-temperature thermal shock tests.

[0128] Regarding porosity, the porosities of Examples 1-9 were all below 0.45%, significantly better than the corresponding effect obtained by nitrogen-cooled gas-powered spraying in Comparative Example 1. Regarding bonding strength, Examples 1-9 all maintained a high strength of 67 MPa to 81 MPa, significantly better than the corresponding effect obtained by nitrogen-cooled gas-powered spraying in Comparative Example 1. High-temperature friction and wear performance tests showed that Examples 1-9 all maintained a low wear amount of 0.0021 g to 0.0023 g, significantly better than the corresponding effect obtained by nitrogen-cooled gas-powered spraying in Comparative Example 1. Thermal shock resistance tests showed that the coatings of Examples 1-9 did not crack after 100 thermal shock cycles, significantly better than the corresponding effect obtained by nitrogen-cooled gas-powered spraying in Comparative Example 1. It should be noted that the surface laser power has a significant impact on performance: excessively high power leads to increased porosity (as in Comparative Example 16).

[0129] In summary, this invention roughens the surface of the turbine outer ring substrate using laser cleaning before spraying, reducing the interface contamination rate and enhancing the adhesion between the coating and the substrate. Furthermore, through a laser-composite nitrogen-cooled gas-powered spraying process, a CoNiCrAlY coating with excellent bonding strength, long-lasting oxidation resistance, and high-temperature resistance is efficiently and cost-effectively prepared. This effectively prevents wear and high-temperature corrosion of the turbine outer ring substrate, providing a reliable solution for the stable operation of the turbine outer ring. The preparation method provided by this invention can be achieved in one step, is simple to operate, and produces quickly. It eliminates the need for vacuum stress-relief heat treatment during coating deposition and the need for switching compressed gases, resulting in low cost, high efficiency, minimal equipment wear, and ease of large-scale production.

[0130] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A turbine outer ring, characterized in that, The turbine outer ring includes a turbine outer ring substrate and a CoNiCrAlY high-temperature protective coating disposed on the surface of the turbine outer ring substrate; The turbine outer ring substrate is composed of multiple independent sealing blocks spliced ​​together; the surface of the sealing blocks has a uniformly distributed micro-serrated structure; The CoNiCrAlY high-temperature protective coating includes a transition layer formed by high-power deposition near the turbine outer ring substrate interface and a surface layer formed by low-power deposition on the surface of the transition layer; wherein the thickness and porosity of the transition layer are lower than those of the surface layer; and there is no obvious delamination between the transition layer and the surface layer.

2. The turbine outer ring according to claim 1, characterized in that, The total thickness of the high-temperature protective coating is 1.5mm to 2.0mm; And / or, the thickness of the transition layer is 0.1 mm to 0.3 mm, and the porosity is ≤0.1%; And / or, the thickness of the surface layer is 1.2mm~1.9mm, and the porosity is ≤0.45%; Preferably, the CoNiCrAlY powder used in the transition layer and the surface layer has a particle size of 5μm to 80μm.

3. The turbine outer ring according to claim 1, characterized in that, The micro-serrated structure is formed by removing localized substrate material using laser cleaning, and the removed area and the uncleaned area form the micro-serrated structure. Preferably, the surface roughness of the micro-serrated structure is ≤8μm.

4. The turbine outer ring according to any one of claims 1 to 3, characterized in that, The turbine outer ring also has at least one of the following characteristics: Feature 1: The porosity of the CoNiCrAlY high-temperature protective coating does not exceed 0.45%; Feature 2: The bonding strength between the turbine outer ring substrate and the CoNiCrAlY high-temperature protective coating is not less than 64 MPa; Feature 3: The wear amount of the CoNiCrAlY high-temperature protective coating does not exceed 0.0023g; Feature 4: The coefficient of friction of the CoNiCrAlY high-temperature protective coating does not exceed 0.3895; Feature 5: The CoNiCrAlY high-temperature protective coating has an earthquake resistance of no less than 100 cycles.

5. A method for preparing a turbine outer ring as described in any one of claims 1 to 4, characterized in that, Includes the following steps: The transition layer and the surface layer are sequentially prepared on the surface of the turbine outer ring substrate, followed by heat treatment.

6. The preparation method according to claim 5, characterized in that, Before preparing the transition layer, the turbine outer ring substrate is pretreated. Pretreatment includes: machining, grinding, degreasing, and roughening the surface of the sealing block in the turbine outer ring matrix; Preferably, laser cleaning is used for roughening to form the micro-serrated structure; Preferably, the conditions for laser cleaning include: laser power of 50W~200W; focal length of the laser source to the substrate surface of 50mm~100mm; angle between the laser source and the substrate surface of 30°~80°; and moving speed of the laser source of 50mm / s~100mm / s.

7. The preparation method according to claim 5, characterized in that, The transition layer is prepared by high-power laser-assisted cold gas spraying. During the laser-composite cold gas power spraying process, the turbine outer ring substrate is fixed on a rotatable three-jaw chuck; the laser and the cold gas power spraying gun are simultaneously integrated on the robotic arm to perform spraying in synchronous motion; The spraying conditions include: laser power of 6kW~10kW, focal length from the laser source to the substrate surface of 350mm~550mm, and angle between the laser source and the substrate surface of 30°~50°; compressed gas pressure of 4MPa~5.5MPa, and compressed gas temperature of 600℃~850℃; spraying distance of 20mm~50mm, spraying angle of 60°~90°, and powder feeding rate of 50g / min~60g / min; the vertical movement speed of the robotic arm of 5mm / s~10mm / s; and the rotational speed of the three-jaw chuck of 50r / min~80r / min. Preferably, the compressed gas is nitrogen.

8. The preparation method according to claim 5, characterized in that, The surface layer is prepared by a low-power laser-composite cold gas dynamic spraying method; During the laser-assisted cold gas spraying process, the turbine outer ring substrate is fixed on a rotatable three-jaw chuck; the laser and the cold gas spraying gun are simultaneously integrated onto a robotic arm for synchronous spraying. The spraying conditions include: laser power of 1kW~4kW, focal length from the laser source to the substrate surface of 350mm~550mm; angle between the laser source and the substrate surface of 30°~50°; compressed gas pressure of 4MPa~5.5MPa, compressed gas temperature of 600℃~800℃; spraying distance of 20mm~50mm, spraying angle of 60°~90°; powder feeding rate of 100g / min~120g / min; vertical movement speed of the robotic arm of 2mm / s~4mm / s; and rotational speed of the three-jaw chuck of 120r / min~180r / min. Preferably, the compressed gas is nitrogen.

9. The preparation method according to claim 5, characterized in that, The heat treatment method is vacuum heat treatment; the temperature of vacuum heat treatment is 800℃~1100℃, and the time of vacuum heat treatment is 3h~5h.

10. An aircraft engine, characterized in that, The aero-engine has a turbine outer ring as described in any one of claims 1 to 4.

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