Integral turbine outer ring low-hardness sealing coating, preparation method and protection tool

Abstract

The invention provides an integral turbine outer ring low-hardness sealing coating, a preparation method and a protection tool. The sealing coating comprises a compact metal bonding layer and a porous abradable sealing surface layer which are sequentially deposited on the surface of the alloy matrix; the main component of the dense metal bonding layer is NiCoCrAlY, and the dense metal bonding layer comprises the following components: 50 to 60 weight percent of Ni, 10 to 15 weight percent of Co, 10 to 15 weight percent of Cr, 5 to 10 weight percent of Al and 0.05 to 2 weight percent of Y. According to the sealing coating, the abrasion condition of the blade can be effectively improved, the gas leakage rate is reduced, and the efficiency of an aero-engine is improved; and an eccentric spraying method is provided for the integral turbine outer ring, the coating preparation method and technological parameters are optimized, the performance of the aero-engine integral turbine outer ring sealing coating is improved, and therefore the more stringent use requirements of contemporary engines are met.

Description

Technical Field

[0001] The present invention relates to the technical field of abradable sealing coatings, and in particular to an integral turbine outer ring low-hardness sealing coating, a preparation method and protective tooling. Background Art

[0002] With the rapid development of my country's aviation sector, aircraft engine design is driven by the pursuit of higher thrust-to-weight ratios, higher efficiency, lower energy consumption, and longer lifespans. The performance of some existing engines is no longer able to meet these demands. In recent decades, gas turbine engine performance has been gradually improved through increased core temperatures, the adoption of lightweight materials, and the application of advanced structural designs. Furthermore, controlling the clearance between the rotating and stationary components of turbomachinery can further enhance engine efficiency. Ideally, the working medium of an engine should flow along the intended flow path over the rotor surface. In reality, however, the gap between the rotor and stator generates leakage flow that bypasses the rotor tip, failing to contribute to power output and ultimately resulting in a loss of overall efficiency. Traditional solutions often employ conservative designs with large clearances. This not only leads to excessive tip leakage but also generates vortices at the blade tips due to interaction with the main flow. Numerous studies have demonstrated the impact of excessive clearances on engine performance and efficiency. However, excessively small clearances inevitably cause friction and collision between the rotating blades and the casing, ultimately leading to damage to multiple components or even catastrophic failure. In order to solve the above problems, in a compressor or turbine, an abradable sealing coating is prepared by thermal spraying as a casing lining around the rotor tip.

[0003] At the same time, with the development of aircraft engines, more and more designs have emerged in which the guide vanes and turbine outer rings are integrated. This one-piece turbine outer ring significantly reduces assembly difficulty and improves assembly precision. Traditional sealing coatings are usually applied to split turbine outer rings. The traditional split turbine outer ring sealing coating preparation process cannot be directly applied to this one-piece turbine outer ring. Otherwise, problems such as contamination of the non-sprayed surface and severe uneven coating thickness will occur.

[0004] In summary, how to develop and prepare a low-hardness sealing coating for an integral turbine outer ring is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0005] In response to the problems that may occur in the sealing coating of the integral turbine outer ring, such as contamination of the non-sprayed surface and serious uneven coating thickness, the embodiments of the present invention provide a low-hardness sealing coating, preparation method and protective tooling for the integral turbine outer ring. The sealing coating of the present invention can effectively improve the wear of the blades, reduce the amount of gas leakage, and improve the efficiency of the aircraft engine; and optimize the coating preparation method and process parameters, thereby improving the performance of the sealing coating of the integral turbine outer ring of the aircraft engine, thereby meeting the more stringent use requirements of modern engines.

[0006] The embodiment of the present application provides the following technical solutions: a low-hardness sealing coating for an integral turbine outer ring, the sealing coating comprising a dense metal bonding layer and a porous abradable sealing surface layer sequentially deposited on the surface of an alloy substrate; The main component of the dense metal bonding layer is NiCoCrAlY, which includes 50-60 wt.% Ni, 10-15 wt.% Co, 10-15 wt.% Cr, 5-10 wt.% Al, and 0.05-2 wt.% Y; the main component of the porous abradable sealing surface layer is a metal coating or a ceramic coating.

[0007] According to one embodiment of the present application, the porous abradable sealing surface layer adopts any one of an Al-Si based sealing coating, a NiCoCrAlY based sealing coating, and a YSZ based sealing coating, wherein the porous abradable sealing surface layer includes 10 to 25 wt.% of polyphenylene ester.

[0008] According to one embodiment of the present application, the porous abradable sealing surface layer adopts a NiCoCrAlY-based sealing coating, wherein the components of the NiCoCrAlY-based sealing coating include 30-60 wt.% Ni, 15-30 wt.% Co, 15-30 wt.% Cr, 3-5 wt.% Al, and 0.05-2 wt.% Y.

[0009] According to one embodiment of the present application, the thickness of the dense metal bonding layer is 0.1~0.5 mm, and the standard deviation of the coating thickness at different locations is less than 20μm; the thickness of the porous abradable sealing surface layer is 0.2~1.5 mm, and the standard deviation of the coating thickness at different locations is less than 50μm.

[0010] The present application also provides a method for preparing a low-hardness sealing coating on an integral turbine outer ring, which mainly comprises the following steps: Step 1: Install the spray protection tooling and pre-treat the alloy substrate surface of the turbine outer ring; Step 2: preparing a dense metal bonding layer on the surface of the alloy substrate; the dense metal bonding layer is mainly composed of NiCoCrAlY, and the components include 50-60 wt.% Ni, 10-15 wt.% Co, 10-15 wt.% Cr, 5-10 wt.% Al, and 0.05-2 wt.% Y; Step 3: Prepare a porous abradable sealing surface layer on the dense metal bonding layer by atmospheric plasma spraying.

[0011] According to an embodiment of the present application, step 3 includes: Step 3.1, place the workpiece with the dense metal bonding layer prepared into a fixture and fix it on the automatic rotating table; Step 3.2, manually control the robot spray gun outlet to align with the corresponding spraying position of the workpiece, and set the robot motion trajectory, speed and other parameters; Step 3.3: Set the spray current to 180 A–250 A, the gas flow rate to 20–70 slpm for Ar and 15 slpm for H22. After the plasma arc stabilizes, preheat the workpiece to 80–200°C. Step 3.4: Start the powder feeder to deposit the porous abradable sealing surface layer; set the process parameters as follows: powder feeding rate 1-12 g / min, powder feeding angle 60-90°, powder feeding carrier gas rate 5-15 L / min, spraying power 15 kW-40 kW, spraying distance 60-150 mm, and deposition time 10 min-80 min; thereby producing the porous abradable sealing surface layer; Step 3.5: Turn off the plasma spray gun and finish spraying; after the workpiece cools down, perform post-processing operations and polish and clean the non-sprayed surface.

[0012] According to an embodiment of the present application, an eccentric spraying method is adopted in step 3, and the eccentric spraying method is: the position of the spray gun is deviated from the center position of the circular turbine component, so that the spray beam and the base surface of the turbine component form a non-orthogonal incidence spraying method.

[0013] According to an embodiment of the present application, during the spraying process of step 3, the outer ring of the turbine is rotated on a rotating table at a speed of 30-90 r / min, and the angle between the tangent vector of the rotation direction and the flame vector direction is less than 90°.

[0014] The present application also provides a spray protection tool for an integral turbine outer ring low-hardness sealing coating, which is used to shield and protect non-spraying areas. The spray protection tool comprises: The assembly surface protection tooling and the blade protection tooling, the assembly surface protection tooling is in the shape of a hollow ring, fixedly installed around the outer ring of the turbine, and is used to protect the non-sprayed assembly surface area of ​​the outer ring of the turbine. The blade protection tooling is circular, installed in the central area of ​​the outer ring of the turbine, and is used to protect the blades in the middle of the outer ring; wherein the thickness of the blade protection tooling gradually decreases from the central area to the edge.

[0015] According to one embodiment of the present application, the thickness of the assembly surface protection tooling is 3-10 mm, and the thickness of the edge portion of the blade protection tooling is 3-5 mm.

[0016] Compared with traditional sealing coatings, the at least one technical solution adopted in the embodiments of this specification can achieve the following beneficial effects: (1) The embodiment of the present invention optimizes the coating composition to obtain a low-hardness sealing coating, reduces the Al content, increases the Co and Cr contents, ensures the high-temperature oxidation resistance of the coating, and reduces the coating hardness to less than 65HR15Y.

[0017] (2) The embodiments of the present invention are designed with blade protection fixtures having reinforcing ribs or a "thick in the middle, thin at the edges" variable thickness structure, and using materials with low internal stress such as aluminum alloy, which effectively prevents the baffle from being bent and deformed due to heat during the spraying process, thereby preventing the baffle from obstructing the spraying surface.

[0018] (3) The embodiment of the present invention adopts the spraying technology path of "eccentric spraying + flame rotation + low power", which successfully solves the problems of flame flow turbulence, uneven thickness, particle sputtering, etc. encountered in the spraying process of the integral turbine outer ring coating, and realizes the high-quality preparation of the integral turbine outer ring sealing coating, with a smooth coating surface and uniform thickness. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0020] Figure 1 1. It is a schematic flow chart of a method for preparing a low-hardness sealing coating on an integral turbine outer ring according to an embodiment of the present invention; Figure 2 This is a first schematic diagram of the rotation direction and eccentric spraying of the integral turbine outer ring according to an embodiment of the present invention; Figure 3 This is a second schematic diagram of the rotation direction and eccentric spraying of the integral turbine outer ring according to an embodiment of the present invention; Figure 4 Schematic diagram of an assembly surface protection tooling according to an embodiment of the present invention; Figure 5 2. It is a schematic diagram of a blade protection tooling according to an embodiment of the present invention; Figure 6 It is a schematic diagram of the structure of the blade protection tooling provided with reinforcing ribs according to an embodiment of the present invention. DETAILED DESCRIPTION

[0021] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0022] The following describes the embodiments of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, in the absence of conflict, the features in the following embodiments and embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of this application.

[0023] An embodiment of the present invention provides a low-hardness sealing coating for an integral turbine outer ring, wherein the sealing coating includes a dense metal bonding layer and a porous abradable sealing surface layer deposited in sequence on the surface of an alloy substrate; the dense metal bonding layer is mainly composed of NiCoCrAlY, and its components include 50-60 wt.% Ni, 10-15 wt.% Co, 10-15 wt.% Cr, 5-10 wt.% Al, and 0.05-2 wt.% Y; the porous abradable sealing surface layer is mainly composed of a metal coating or a ceramic coating.

[0024] The embodiment of the present invention is prepared by atmospheric plasma spraying. The thickness of the dense metal bonding layer is 0.1~0.5 mm, and the standard deviation of the coating thickness at different locations is less than 20μm; the thickness of the porous abradable sealing surface layer is 0.2~1.5mm, and the standard deviation of the coating thickness at different locations is less than 50μm. The thickness of the porous abradable sealing surface layer can reach more than 1 mm, and the coating thickness at different locations is uniform with a standard deviation of no more than 50μm. The prepared coating surface is smooth with a roughness Ra of 6.3~12.5μm.

[0025] In some embodiments of the present invention, the porous abradable sealing surface layer comprises any one of an Al-Si-based sealing coating, a NiCoCrAlY-based sealing coating, and a YSZ-based sealing coating, wherein the porous abradable sealing surface layer comprises 10-25 wt.% polyphenylene ester. The porous abradable sealing surface layer uses 10-25 wt.% polyphenylene ester as a pore-forming agent to increase the porosity of the coating. The mass fraction of polyphenylene ester needs to be analyzed based on actual service conditions and blade material to balance bonding strength and scrapeability.

[0026] In an embodiment of the present invention, the porosity of the porous abradable sealing surface layer is greater than 30%, the bonding strength exceeds 10 MPa, and the surface Rockwell hardness is less than 65 HR15Y.

[0027] In one embodiment of the present invention, the porous abradable sealing surface layer utilizes a NiCoCrAlY-based sealing coating, wherein the components of the NiCoCrAlY-based sealing coating include 30-60 wt.% Ni, 15-30 wt.% Co, 15-30 wt.% Cr, 3-5 wt.% Al, and 0.05-2 wt.% Y. The NiCoCrAlY-based sealing coating comprises NiCoCrAlY and 15% wt.% polyphenylene ester. NiCoCrAlY has a low Al content and high Co and Cr content, which reduces the β hard phase content while maintaining the coating's high-temperature oxidation resistance, thereby further reducing the coating's hardness.

[0028] In a preferred embodiment, the composition of the porous abradable sealing surface layer NiCoCrAlY is: 50-60 wt.% Ni, 15-20 wt.% Co, 15-20 wt.% Cr, 3-5 wt.% Al, and 0.05-2 wt.% Y.

[0029] In a preferred embodiment, the dense metal bonding layer NiCoCrAlY has a composition of 50-60 wt.% Ni, 10-12 wt.% Co, 10-12 wt.% Cr, 7-10 wt.% Al, and 0.05-2 wt.% Y, and is prepared by atmospheric plasma spraying.

[0030] The dense metal bonding layer and the porous abradable sealing surface layer are both NiCoCrAlY, but the specific compositions are different. The characteristic is that the porous abradable sealing surface layer has a lower Al content and higher Co and Cr contents, which can achieve the goal of reducing the hardness of the surface layer.

[0031] like Figure 1 As shown, an embodiment of the present invention further provides a method for preparing a low-hardness sealing coating on an integral turbine outer ring, which mainly includes the following steps: Step 1: Install the spray protection tooling and pre-treat the alloy substrate surface of the turbine outer ring; Step 2: preparing a dense metal bonding layer on the surface of the alloy substrate; the dense metal bonding layer is mainly composed of NiCoCrAlY, and the components include 50-60 wt.% Ni, 10-15 wt.% Co, 10-15 wt.% Cr, 5-10 wt.% Al, and 0.05-2 wt.% Y; Step 3: Prepare a porous abradable sealing surface layer on the dense metal bonding layer by atmospheric plasma spraying.

[0032] During specific implementation, the surface of the alloy substrate is pretreated, including surface grease and stain removal, sandblasting and other operations. Before sandblasting, protective tooling must be installed to prevent the non-sprayed surface from being roughened by sandblasting.

[0033] In some embodiments of the present invention, step 3 includes: Step 3.1, place the workpiece with the dense metal bonding layer prepared into a fixture and fix it on the automatic rotating table; Step 3.2, manually control the robot spray gun outlet to align with the corresponding spraying position of the workpiece, and set the robot motion trajectory, speed and other parameters; Step 3.3: Set the spray current to 180 A–250 A, the gas flow rate to 20–70 slpm for Ar and 15 slpm for H22. After the plasma arc stabilizes, preheat the workpiece to 80–200°C. Step 3.4: Start the powder feeder to deposit the porous abradable sealing surface layer. The process parameters are set as follows: powder feeding rate 1-12 g / min, powder feeding angle 60-90°, powder feeding carrier gas rate 5-15 L / min, spraying power 15 kW-40 kW, spraying distance 60-150 mm, and deposition time 10 min-80 min. The porous abradable sealing surface layer having a thickness of 100-1500 μm is obtained. Step 3.5: Turn off the plasma spray gun and finish spraying; after the workpiece cools down, perform post-processing operations and polish and clean the non-sprayed surface.

[0034] In some embodiments of the present invention, Figure 2-Figure 3 As shown, step 3 employs an eccentric spraying method. This involves positioning the spray gun away from the center of the circular turbine component, allowing the spray beam to have non-orthogonal incidence on the component's substrate surface. Optionally, the plasma flame forms an angle of 20 to 80 degrees with the workpiece's spraying surface. This spraying method effectively mitigates flame rebound and turbulence at the interface between the tooling and the outer ring, addressing the issue of uneven coating thickness across the upper and lower portions of the outer ring.

[0035] In some embodiments of the present invention, during the spraying process of step 3, the turbine outer ring is rotated on a rotating table at a speed of 30-90 r / min, and the angle between the tangent vector of the rotation direction and the flame vector direction is less than 90°.

[0036] The preparation method of the embodiment of the present invention adopts the "eccentric spraying + flame rotation + low power" scheme, which solves the problems of flame flow turbulence, uneven thickness, particle sputtering, etc. encountered during the spraying process of the integral turbine outer ring coating, and realizes high-quality preparation of the integral turbine outer ring sealing coating, with a smooth coating surface and uniform thickness.

[0037] like Figure 4-Figure 5 As shown, an embodiment of the present invention also provides a spray protection tooling for a low-hardness sealing coating on an integral turbine outer ring, which is used to shield and protect non-spray areas to prevent contamination of non-spray areas such as blades and assembly surfaces. The spray protection tooling includes: an assembly surface protection tooling and a blade protection tooling. The assembly surface protection tooling is in the shape of a hollow circular ring and is fixedly mounted around the turbine outer ring to protect the non-sprayed assembly surface area of ​​the turbine outer ring. The blade protection tooling is in the shape of a circular shape and is mounted in the central area of ​​the turbine outer ring to protect the blades in the middle of the outer ring. The thickness of the blade protection tooling gradually decreases from the central area to the edge.

[0038] The sealing coating protection tooling in the embodiments of the present invention primarily shields and protects non-sprayed areas, such as blades and assembly surfaces, from contamination. The tooling's structural design must consider the workpiece size and thermal spray angle. While ensuring adequate protection of the non-sprayed areas, the tooling must not obstruct or affect the coating quality in the sprayed areas.

[0039] In specific implementation, the tooling structure design needs to be combined with the workpiece size and thermal spraying angle. On the one hand, the tooling should fully protect the non-spraying area as much as possible, and on the other hand, it should not block the spraying area and should not affect the coating quality of the spraying area. The following formula can be used to preliminarily calculate the stiffness of the circular thin-walled tooling: D = E * h³ * I / 12 Stiffness (D) is related to the material's elastic modulus (E), section moment of inertia (I), and thickness (h). In practical engineering, finite element analysis or experimental verification is required to verify stiffness behavior under complex thermal load boundary conditions and irregular structures. If structures such as stiffeners are present, their contribution must be additionally calculated.

[0040] During specific implementation, the assembly surface protection tooling is in the shape of a hollow ring, and the material can usually be stainless steel, aluminum alloy, heat-resistant steel, etc., with uniform thickness, high rigidity, and not easy to deform, and the thickness can be 3~10 mm. The blade protection tooling is circular, and the diameter depends on the size of the workpiece, about 100~500mm, and the material includes but is not limited to stainless steel, aluminum alloy, heat-resistant steel, etc. In order to avoid blocking the spraying surface, the thickness of the edge should not be too large, about 3~5 mm; in order to ensure that it does not buckle and deform when heated, the tooling adopts various means such as reinforcing ribs and variable thickness to improve the rigidity of the blade protection tooling. At the same time, it is considered to give priority to the use of aluminum alloy materials with less internal stress, or heat-resistant steel and other materials that have been annealed to relieve stress.

[0041] In some embodiments of the present invention, the assembly surface protection tooling uses a combination of "screw + 0.1mm gasket + nut" to accurately adjust the distance between the tooling and the workpiece. The operation is simple and easy to adjust to the optimal distance.

[0042] Example 1: A GH4169 high-temperature alloy integral turbine outer ring is prepared with a 1000°C resistant abradable sealing coating, including the following: (1) Coating material system: Based on the target operating temperature and performance requirements, this embodiment intends to adopt the atmospheric plasma spraying technology of "dense NiCoCrAlY bonding layer + NiCoCrAlY-based sealing surface layer". The target thickness of the bonding layer is 0.2mm, and the target thickness of the sealing surface layer is 1mm. At the same time, considering the requirements of low hardness and high bonding strength, the coating composition is optimized and selected as follows: (2) The dense NiCoCrAlY bonding layer has the following composition: 50-60 wt.% Ni, 10-15 wt.% Co, 10-15 wt.% Cr, 5-10 wt.% Al, and 0.05-2 wt.% Y, and is prepared by atmospheric plasma spraying.

[0043] (3) The surface layer of the NiCoCrAlY-based sealing coating is composed of NiCoCrAlY and 15% wt.% polyphenylene ester. NiCoCrAlY has a low Al content and high Co and Cr content, which reduces the β hard phase content while maintaining the high-temperature oxidation resistance of the coating, thereby further reducing the coating hardness. NiCoCrAlY specifically contains 50-60 wt.% Ni, 15-20 wt.% Co, 15-20 wt.% Cr, 3-5 wt.% Al, and 0.05-2 wt.% Y.

[0044] (4) Design the protective tooling structure. The assembly surface protection tooling is located around the outer ring of the turbine and is mainly used to protect the non-sprayed assembly surface area of ​​the outer ring; the blade baffle is located in the center area of ​​the outer ring of the turbine and is mainly used to protect the blades in the middle of the outer ring from contamination.

[0045] (5) The assembly surface protection tooling is in the shape of a hollow ring, and the material is usually stainless steel with an inner diameter of 370 mm, an outer diameter of 400 mm, and a thickness of 5 mm.

[0046] (6) The blade protection tooling is circular, with a diameter of 370 mm, made of aluminum alloy, and 3 mm thick at the edge; to ensure that it does not buckle and deform under heat, the tooling design is as follows: Figure 5 The "thick in the middle, thin at the edge" variable thickness structure shown improves the rigidity of the blade protection tooling.

[0047] (7) Use alcohol and absorbent cotton to clean the area of ​​the workpiece to be sprayed to remove surface oil and other dirt.

[0048] (8) Install the tooling, adjust the number of stainless steel gaskets to adjust the distance between the tooling and the workpiece to 5 mm, and tighten the tooling with bolts.

[0049] (9) White corundum was used to pre-treat the surface of the sprayed area to improve the bonding strength between the coating and the substrate. The particle size of the white corundum used was 60 mesh, the sandblasting pressure was 0.2~0.5MPa, and the sand was blown evenly at an angle of 80° for 30 minutes. The surface roughness of the sprayed surface reached Ra5.0 μm~Ra 7.0 μm.

[0050] (10) The outer ring of the turbine is fixed on the turntable by a screw. During the spraying process, the turntable rotates continuously at a speed of 60 r / min to ensure uniform distribution of the circumferential coating thickness.

[0051] (11) Set the spraying path. Since the shielding tooling is very close to the outer ring and the flame rebounds easily, the coating thickness is thin at the root of the outer ring. Therefore, an eccentric spraying path is required. The spray gun is located at 1 / 4 of the diameter of the turbine outer ring. The angle between the plasma flame and the workpiece rotation tangent vector is 60°. The spray gun is scanned up and down at a speed of 5 mm / min. One scan up and down is considered a cycle. The number of cycles is set to 60 according to the coating thickness requirement.

[0052] (12) A dense metal bonding layer NiCoCrAlY ~0.2 mm was prepared on the alloy substrate.

[0053] (13) Select appropriate spraying process parameters and spray to prepare the abradable sealing surface layer. Spraying power ~25kW, spraying distance ~100 mm, spraying current ~200 A, gas flow rate of Ar ~50 slpm, H2 ~4 slpm, after the plasma arc is stable, preheat the workpiece to ~180℃; powder feeding rate ~4 g / min, powder feeding angle 90°, powder feeding carrier gas rate ~5 L / min, deposition time ~80 min; a porous abradable sealing surface layer with a thickness of ~1 mm is obtained; (14) After the coating spraying is completed, the coating thickness is measured using a micrometer. Different positions are selected for measurement and record. The measurement results are shown in Table 1.

[0054] (15) Post-processing: remove the masking tooling and high-temperature tape, etc., and polish the small amount of coating on the assembly surface.

[0055] Table 1 Coating thickness values

[0056] As shown in Table 1, it can be seen that the abradable seal layer is very close to the target thickness of 1 mm, and the average thickness of the upper and lower parts is only 0.022 mm, which fully meets the requirements.

[0057] Example 2: Design of protective tooling structure The step (4) of designing the protective tooling structure in Example 1 is described in detail.

[0058] (1) Determine the protection area and size: Analyze the area to be sprayed and the area to be protected on the workpiece, determine the shape and size of the protection tooling, and determine that the assembly surface protection tooling is a hollow ring with an inner diameter of 370 mm and an outer diameter of 400 mm; the blade protection tooling is circular with a diameter of 370 mm.

[0059] (2) Determine the constraint boundary conditions: The inner diameter of the assembly surface protection tooling is constrained to 370 mm, and there are no constraints in the outer diameter and thickness directions. The outer diameter of the blade protection tooling is constrained to 370 mm, and a thickness exceeding 3 mm will cause the area to be sprayed to be blocked, so the maximum thickness is selected as 3 mm.

[0060] (3) Preliminary calculation of tooling stiffness is performed according to the following formula: D = E * h³ * I / 12 Among them, stiffness (D) is related to the material elastic modulus (E), section moment of inertia (I) and thickness (h).

[0061] (4) Combine finite element analysis to evaluate workpiece stiffness: Combine finite element analysis to verify the stiffness performance under complex thermal load boundary conditions and irregular structures. The analysis found that the stiffness of the assembly surface protection tooling in this solution is sufficient to resist thermal stress, while the stiffness of the blade protection tooling is insufficient. During the thermal spraying process, the blade protection tooling may bend and deform, which may cause the area to be sprayed to be blocked on the one hand and the area to be protected to be insufficient on the other hand. Therefore, structural optimization is required.

[0062] (5) Tooling structure optimization: Tooling design such as Figure 5 The "thick in the middle, thin at the edge" variable thickness structure shown in the figure improves the rigidity of the blade protection tooling. Figure 6 The rib structure shown improves the tooling stiffness while satisfying boundary constraints.

[0063] (6) Combining finite element analysis and experimental verification: After optimizing the tooling structure, finite element analysis is first used to verify the stiffness performance under mixed thermal load boundary conditions and irregular structures; then a simulated spraying experiment is carried out, the workpiece is preheated to a spraying temperature of 200°C, and it is observed that the tooling does not undergo buckling deformation, which means that the requirements are met.

[0064] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A low-hardness sealing coating for an integral turbine outer ring, characterized in that: The sealing coating comprises a dense metal bonding layer and a porous abradable sealing surface layer deposited in sequence on the surface of the alloy substrate; The main component of the dense metal bonding layer is NiCoCrAlY, which includes 50-60 wt.% Ni, 10-15 wt.% Co, 10-15 wt.% Cr, 5-10 wt.% Al, and 0.05-2 wt.% Y; the main component of the porous abradable sealing surface layer is a metal coating or a ceramic coating.

2. The low-hardness sealing coating for the integral turbine outer ring according to claim 1 is characterized in that: The porous abradable sealing surface layer is any one of an Al-Si based sealing coating, a NiCoCrAlY based sealing coating, and a YSZ based sealing coating, wherein the porous abradable sealing surface layer includes 10 to 25 wt.% of polyphenylene ester.

3. The low-hardness sealing coating for the integral turbine outer ring according to claim 2, characterized in that: The porous abradable sealing surface layer adopts a NiCoCrAlY-based sealing coating, wherein the components of the NiCoCrAlY-based sealing coating include 30-60 wt.% Ni, 15-30 wt.% Co, 15-30 wt.% Cr, 3-5 wt.% Al, and 0.05-2 wt.% Y.

4. The low-hardness sealing coating for the integral turbine outer ring according to claim 1, characterized in that: The thickness of the dense metal bonding layer is 0.1~0.5 mm, and the standard deviation of the coating thickness at different locations is less than 20μm; the thickness of the porous abradable sealing surface layer is 0.2~1.5 mm, and the standard deviation of the coating thickness at different locations is less than 50μm.

5. A method for preparing a low-hardness sealing coating for an integral turbine outer ring according to any one of claims 1 to 4, characterized in that: The main steps include: Step 1: Install the spray protection tooling and pre-treat the alloy substrate surface of the turbine outer ring; Step 2: preparing a dense metal bonding layer on the surface of the alloy substrate; the dense metal bonding layer is mainly composed of NiCoCrAlY, and the components include 50-60 wt.% Ni, 10-15 wt.% Co, 10-15 wt.% Cr, 5-10 wt.% Al, and 0.05-2 wt.% Y; Step 3: Prepare a porous abradable sealing surface layer on the dense metal bonding layer by atmospheric plasma spraying.

6. The preparation method according to claim 5, characterized in that Step 3 includes: Step 3.1, place the workpiece with the dense metal bonding layer prepared into a fixture and fix it on the automatic rotating table; Step 3.2, manually control the robot spray gun outlet to align with the corresponding spraying position of the workpiece, and set the robot motion trajectory, speed and other parameters; Step 3.3: Set the spray current to 180 A–250 A, the gas flow rate to 20–70 slpm for Ar and 2–15 slpm for H2. After the plasma arc stabilizes, preheat the workpiece to 80–200°C. Step 3.4: Start the powder feeder to deposit the porous abradable sealing surface layer; set the process parameters as follows: powder feeding rate 1-12 g / min, powder feeding angle 60-90°, powder feeding carrier gas rate 5-15 L / min, spraying power 15 kW-40 kW, spraying distance 60-150 mm, and deposition time 10 min-80 min; thereby producing the porous abradable sealing surface layer; Step 3.5: Turn off the plasma spray gun and finish spraying; after the workpiece cools down, perform post-processing operations and polish and clean the non-sprayed surface.

7. The preparation method according to claim 5, characterized in that In step 3, an eccentric spraying method is used. The eccentric spraying method is: the position of the spray gun is deviated from the center position of the circular turbine component, so that the spray beam forms a non-orthogonal incidence with the base surface of the turbine component.

8. The preparation method according to claim 5, characterized in that During the spraying process of step 3, the turbine outer ring is rotated on a rotating table at a speed of 30-90 r / min, and the angle between the tangent vector of the rotation direction and the flame vector direction is less than 90°.

9. A protective tool for spraying a low-hardness sealing coating on an integral turbine outer ring according to any one of claims 1 to 4, used for shielding and protecting a non-spraying area, characterized in that: The spray protection tooling comprises: The assembly surface protection tooling and the blade protection tooling, the assembly surface protection tooling is in the shape of a hollow ring, fixedly installed around the outer ring of the turbine, and is used to protect the non-sprayed assembly surface area of ​​the outer ring of the turbine. The blade protection tooling is circular, installed in the central area of ​​the outer ring of the turbine, and is used to protect the blades in the middle of the outer ring; wherein the thickness of the blade protection tooling gradually decreases from the central area to the edge.

10. The spray protection tooling according to claim 9, characterized in that: The thickness of the assembly surface protection tooling is 3-10 mm, and the thickness of the edge of the blade protection tooling is 3-5 mm.

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