Method of repairing thermal barrier coating and thermal barrier coating
By combining force-controlled grinding and multi-arc ion plating with vacuum heat treatment, the problem of controllable removal of the MCrAlY adhesive layer in the repair of thermal barrier coatings was solved, achieving low-cost and efficient repair without damage to the substrate.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BEIJING GOLDEN WHEEL SPECIAL MACHINE
- Filing Date
- 2026-05-13
- Publication Date
- 2026-06-26
Smart Images
Figure CN122279474A_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of coating preparation technology, specifically relating to a method for repairing thermal barrier coatings and a thermal barrier coating. Background Technology
[0002] Thermal barrier coatings (TBCs) are a crucial technology for manufacturing advanced aero-engine and gas turbine hot-end components, playing a vital role in improving engine performance and turbine blade life. TBCs typically consist of an antioxidant bonding layer and a thermally insulating ceramic layer. Among these, the bonding layer of TBCs utilizes MCrAlY (where M represents Ni, Co, or Ni+Co) with a wide composition range. Its composition can be adjusted according to engine service conditions and TBC failure modes to optimize the antioxidant and corrosion resistance of the MCrAlY bonding layer. Furthermore, its preparation process is relatively simple and low-cost, making MCrAlY one of the most important bonding layers in TBCs. It is widely used in aero-engine and gas turbine turbine blades, combustion chambers, fuel nozzles, and other hot-end components. Since engine lifespan typically far exceeds the repair cycle of hot-end components, repairing and reusing engine hot-end components is an effective way to reduce engine costs. TBC repair is a crucial step in the reuse of engine hot-end components.
[0003] The repair of thermal barrier coatings for hot-end components mainly includes the removal and recoating of thermal barrier coatings. The removal of thermal barrier coatings is the most difficult part of thermal barrier coating repair. In particular, under the service conditions of engines, there will inevitably be high-temperature oxidation corrosion and interdiffusion between the adhesive layer and the substrate, which will cause degradation and performance decline of the MCrAlY adhesive layer. Controllable removal of the MCrAlY adhesive layer has become the key to thermal barrier coating repair.
[0004] In related technologies, the removal of MCrAlY adhesive layer usually employs sandblasting or chemical pickling. However, since the composition of MCrAlY adhesive layer is similar to that of the substrate, and the MCrAlY adhesive layer and the substrate interdiffusion occurs, the above methods for adhesive layer removal all present problems such as difficulty in control and risk of damage to the substrate.
[0005] Therefore, due to the complex composition of the MCrAlY binder layer, the varying degrees of binder degradation, and the formation of a diffusion layer through interdiffusion between the binder layer and the substrate, the controlled removal of the binder layer, especially after service, using sandblasting or chemical pickling methods is difficult and costly. Consequently, the controlled removal of the MCrAlY binder layer without damaging the substrate has become a key research and application direction for the recoating of thermal barrier coatings using MCrAlY as the binder layer. Summary of the Invention
[0006] The purpose of this application is to provide a method for repairing thermal barrier coatings and a thermal barrier coating, which can alleviate the problems of high difficulty and high cost in the controllable removal of the adhesive layer of thermal barrier coatings after service. It can controllably remove the MCrAlY adhesive layer without damaging the substrate, and the cost is low and the coating quality is stable.
[0007] To solve the above-mentioned technical problems, this application is implemented as follows: According to one aspect of this application, an embodiment of this application provides a method for repairing a thermal barrier coating, the repair method comprising: A thermal barrier coating to be repaired is provided, the thermal barrier coating to be repaired comprising a substrate, an adhesive layer to be repaired disposed on the substrate, and a ceramic layer; Remove the ceramic layer; The degradation status of the adhesive layer to be repaired is assessed; The repair method for the adhesive layer to be repaired is determined based on the evaluation results. When it is necessary to repair the adhesive layer to be repaired, a preset thickness of the adhesive layer to be repaired is removed by force-controlled grinding, and then an adhesive layer of a preset thickness is deposited to form the target adhesive layer. A ceramic layer is formed on the surface of the target adhesive layer.
[0008] In an optional embodiment, the removal of the ceramic layer includes removing the ceramic layer by means of high-pressure water jet.
[0009] In an optional embodiment, the operating conditions of the high-pressure water jet include: a pressure of 100 MPa to 300 MPa and a distance of 10 mm to 30 mm between the nozzle and the thermal barrier coating.
[0010] In an optional embodiment, after removing the ceramic layer and before assessing the degradation status of the adhesive layer to be repaired, a step of surface treatment of the adhesive layer to be repaired is further included.
[0011] In an optional embodiment, the surface treatment includes: sandblasting and cleaning the surface of the adhesive layer to be repaired to remove the thermally grown oxide layer on the surface of the adhesive layer to be repaired, wherein the sandblasting medium has a mesh size of 150 to 300 mesh and the sandblasting pressure is 0.1 MPa to 0.2 MPa.
[0012] In an optional embodiment, the adhesive layer to be repaired comprises an MCrAlY adhesive layer, wherein M comprises at least one or both of nickel or cobalt.
[0013] In an optional embodiment, the degradation status assessment of the adhesive layer to be repaired includes: performing X-ray fluorescence spectroscopy analysis on the adhesive layer to be repaired to obtain XRF data of the MCrAlY adhesive layer, wherein the XRF data includes the content of Al element.
[0014] In an optional embodiment, determining the repair method for the adhesive layer to be repaired based on the evaluation results includes: Based on the Al content in the obtained XRF data, if the ratio of the Al content in the adhesive layer to be repaired to the Al content in the adhesive layer before degradation is less than a first threshold, then the adhesive layer to be repaired needs to be repaired; if the ratio of the Al content in the adhesive layer to be repaired to the Al content in the adhesive layer before degradation is greater than or equal to the first threshold, then the adhesive layer to be repaired does not need to be repaired.
[0015] In an optional embodiment, the Al content in the adhesive layer before degradation is denoted as w0, and the thickness of the adhesive layer before degradation is denoted as h0; The Al content in the adhesive layer to be repaired in the XRF data is denoted as w1; The Al content in the redeposited adhesive layer of a predetermined thickness is denoted as w2, and the predetermined thickness is denoted as h2; When w1≥90%w0, the adhesive layer to be repaired does not need to be repaired. When 70%w0≤w1<90%w0, the adhesive layer to be repaired needs to be repaired, and the following conditions must be met: w2: w0 is 1.1~1.3, h2=0.2~0.5h0; When w1 < 70%w0, the adhesive layer to be repaired needs to be repaired, and the following conditions must be met: w2: w0 is 1 to 1.1, h2 = 0.5 to 0.8h0.
[0016] In an optional embodiment, the operating conditions for force-controlled grinding include: the grinding head is made of at least one of alumina or silicon carbide; the mesh size of the grinding head is 100 to 3000; and the pressure is 10N to 30N.
[0017] In an optional embodiment, the method of redepositing the adhesive layer of a predetermined thickness includes: preparing the adhesive layer using a multi-arc ion plating process.
[0018] In an optional embodiment, the operating conditions of the multi-arc ion plating process include: the target material includes a primary target material and a supplementary target material, wherein the mass content of Al in the supplementary target material is 80wt% to 90wt%, the mass content of Y is 0.5wt% to 1.5wt%, the arc current of the primary target material is 60A to 100A, and the arc current of the supplementary target material is 30A to 70A; the substrate bias voltage is -30V to -70V.
[0019] In an optional embodiment, after forming the target adhesive layer and before forming the ceramic layer, a step of vacuum heat treatment of the target adhesive layer is further included.
[0020] In an optional embodiment, the operating conditions for the vacuum heat treatment include: a temperature of 850℃~1050℃, a time of 1h~4h, and a vacuum degree of ≤1×10⁻⁶. -2 Pa.
[0021] In an optional embodiment, the method of forming the ceramic layer includes one or more of atmospheric plasma spraying, electron beam physical vapor deposition, and plasma physical vapor deposition.
[0022] According to another aspect of this application, an embodiment of this application provides a thermal barrier coating, which is repaired using the aforementioned thermal barrier coating repair method.
[0023] Implementing the technical solution of the present invention has at least the following beneficial effects: In this embodiment, the provided method for repairing thermal barrier coatings includes steps such as removing the ceramic layer, assessing the degradation state of the adhesive layer to be repaired, determining the repair method for the adhesive layer to be repaired based on the assessment results, removing the adhesive layer to be repaired to a preset thickness using force-controlled grinding, depositing an adhesive layer of a preset thickness to form a target adhesive layer, and forming a ceramic layer on the surface of the target adhesive layer. The force-controlled grinding method used to remove the degraded adhesive layer has the advantages of controllable removal thickness, high consistency of removal at different locations, and the ability to control removal according to requirements. Furthermore, this invention can achieve partial removal of the degraded adhesive layer through controllable grinding, without the need for complex protective treatments and substrate damage prevention control, making the operation simple.
[0024] Therefore, the repair method of the present invention can be used to solve the problem of coating repair after the service of aero-engine or gas turbine blades. In particular, it can avoid the problems of high control difficulty, interface inclusion, and risk of damage to the substrate caused by the removal of the adhesive layer in the current thermal barrier coating repair process using traditional sandblasting or chemical methods. It has the characteristics of low cost and stable coating quality.
[0025] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description
[0026] Figure 1 This application provides a schematic flowchart of a method for repairing a thermal barrier coating. Figure 2A flowchart illustrating another method for repairing thermal barrier coatings is provided for embodiments of this application. Figure 3 Comparison of the cross-sectional morphology of the MCrAlY adhesive layer in region (a) before and region (b) after the removal of the ceramic layer by high-pressure water, provided in the embodiments of this application; Figure 4 This is a schematic diagram of the cross-sectional morphology of the repaired MCrAlY coating according to an embodiment of this application; Figure 5 The diagram shows the phase structure of the MCrAlY adhesive layer before and after repair in an embodiment of this application. Figure 6 This is a schematic diagram of the thermal barrier coating's antioxidant properties before and after repair of the MCrAlY adhesive layer in an embodiment of this application. Detailed Implementation
[0027] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0028] The endpoints and any values of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of the ranges, the endpoint values of the ranges, or individual point values, and individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following related objects are in an "or" relationship.
[0029] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.
[0030] The embodiments of this application will be described in detail below with reference to the accompanying drawings and specific examples and application scenarios.
[0031] The repair of thermal barrier coatings (TBCs) on hot-end components mainly includes TBC removal and recoating. TBC removal is the most challenging aspect of TBC repair. Methods for removing the ceramic layer primarily include sandblasting, high-pressure water jetting, and molten alkali boiling. These methods generally do not damage the substrate and are well-established. However, under engine service conditions, high-temperature oxidation corrosion and interdiffusion between the bond layer and the substrate inevitably lead to MCrAlY bond layer degradation and performance decline. Therefore, controllable removal of the MCrAlY bond layer is crucial for TBC repair. In related technologies, MCrAlY bond layer removal typically employs sandblasting or chemical pickling. However, because the composition of the MCrAlY bond layer is similar to that of the substrate, and there is interdiffusion between the MCrAlY bond layer and the substrate, these methods present challenges in control and carry the risk of damaging the substrate. Among these methods, sandblasting offers low control precision, while the MCrAlY binder layer has a complex composition. Chemical pickling requires different acid compositions tailored to the MCrAlY binder layer's structure to control corrosion and minimize damage to the substrate. It also necessitates protection of hollow turbine blade cavities or other non-coated areas with paraffin wax or anti-corrosion paint. However, the protection and removal processes are complex, particularly regarding the reliability of internal cavity protection, which is difficult to assess easily. Furthermore, the interdiffusion layer formed between the binder and substrate further complicates the controllable removal of the MCrAlY binder layer. Therefore, a combination of sandblasting and chemical pickling is needed to remove the MCrAlY binder layer. Typically, chemical pickling is performed first, followed by sandblasting. Due to variations in removal rates across different parts of complex turbine blade profiles, this process needs to be repeated. Finally, the above method requires complete removal of the binder layer before recoating with a thermal barrier coating. Therefore, due to the complex composition of the MCrAlY adhesive layer, the varying degrees of adhesive layer degradation, and the formation of diffusion layers through interdiffusion between the adhesive layer and the substrate, the controllable removal of the adhesive layer, especially the adhesive layer of thermal barrier coatings after service, using sandblasting or chemical pickling methods is difficult and costly. Controllable removal of the MCrAlY adhesive layer without damaging the substrate has become a key research and application direction for the recoating of thermal barrier coatings with MCrAlY as the adhesive layer.
[0032] After high-temperature service, the interdiffusion between the adhesive layer and the substrate in engine hot-end components leads to a metallurgical bond, significantly improving their adhesion. Since the adhesive layer is removed through corrosion using chemical pickling, complete removal is necessary to ensure the adhesion of the subsequent thermal barrier coating. However, complete removal of the adhesive layer presents challenges such as difficulty in removal or protection, interface inclusions, and damage to the substrate.
[0033] In view of this, the inventors of this application have discovered that by using a grinding method to controllably remove the adhesive layer, leaving a certain thickness of the original adhesive layer, and then re-preparing an optimized adhesive layer on top of it, combined with diffusion heat treatment and other processes, it is expected to achieve the preparation of an MCrAlY adhesive layer with the target composition. Therefore, this application provides a method for repairing thermal barrier coatings and a thermal barrier coating to overcome the above-mentioned defects in related technologies. The following is a detailed description of this application.
[0034] refer to Figure 1 As shown, in some embodiments, this application provides a method for repairing thermal barrier coatings, the method comprising: A thermal barrier coating to be repaired is provided, the thermal barrier coating to be repaired comprising a substrate, an adhesive layer to be repaired disposed on the substrate, and a ceramic layer; Remove the ceramic layer; Assess the degradation status of the adhesive layer to be repaired; The repair method for the adhesive layer to be repaired will be determined based on the assessment results. When it is necessary to repair the adhesive layer to be repaired, the adhesive layer to be repaired of a preset thickness is removed by force-controlled grinding, and then an adhesive layer of a preset thickness is deposited to form the target adhesive layer. A ceramic layer is formed on the surface of the target adhesive layer.
[0035] The thermal barrier coating repair method provided in this application is applicable to the preparation of thermal barrier coatings for hot-end components of aero-engines and gas turbines, and is particularly applicable to the recoating of thermal barrier coatings with MCrAlY bonding layers after degradation.
[0036] In this embodiment, force-controlled grinding is used to remove part of the adhesive layer to be repaired. Force-controlled grinding allows for the controlled removal of metallic materials by controlling parameters such as grinding pressure, abrasive, and particle size. The composition and microstructure of high-temperature alloys have minimal impact on the force-controlled grinding process, and different materials with varying properties can be removed controllably through parameter control. In particular, for complex turbine blade components in engines, combined with robotic grinding, uniform removal of different parts can be achieved. As an example, under high-temperature conditions, the degradation of the MCrAlY adhesive layer is mainly manifested in the consumption of aluminum (Al) and active elements within the adhesive layer, resulting in an MCrAlY adhesive layer without the target oxidation and corrosion resistance. By combining force-controlled grinding of the remaining adhesive layer composition, designing the composition of the recoated MCrAlY adhesive layer, and vacuum heat treatment, it is hoped that an MCrAlY adhesive layer with the target composition and performance can be prepared. Therefore, in the recoating process of thermal barrier coatings on hot-end components of aero-engines and gas turbines, this embodiment combines force-controlled grinding for controllable removal of the adhesive layer, designing and controlling the composition of the recoated adhesive layer, and achieving the recoating of an MCrAlY adhesive layer with the target composition.
[0037] Therefore, when removing the adhesive layer, especially the MCrAlY adhesive layer, there are several challenges compared to traditional sandblasting methods, which have lower removal precision. Chemical methods require complex removal solutions and processes tailored to the different compositions of the MCrAlY adhesive layer. Furthermore, to prevent corrosion of the substrate by the removal solution, effective protection of uncoated areas and the blade's internal cavity is necessary. Complete removal of the MCrAlY adhesive layer also presents significant challenges in controlling substrate damage. This invention employs automated force-controlled grinding for degraded adhesive layers, particularly the MCrAlY adhesive layer. This method offers advantages such as controllable removal thickness, high consistency in removal across different locations, and customizable removal based on requirements. Moreover, this invention enables controlled grinding of degraded MCrAlY adhesive layers, achieving partial removal without complex protective treatments or substrate damage control. The operation is simple and easy to implement.
[0038] In some embodiments, the adhesive layer to be repaired includes an MCrAlY adhesive layer, wherein M includes at least one or both of nickel (Ni) or cobalt (Co), that is, M can be Ni, Co, or Ni+Co. Of course, M is not limited to these, and may also include other metallic elements (such as Fe). Optionally, the MCrAlY adhesive layer may also contain one or more elements selected from silicon (Si), hafnium (Hf), etc.
[0039] It should be noted that the MCrAlY bonding layer applicable to the embodiments of the present invention includes, but is not limited to, bonding layers with different compositions such as NiCoCrAlY, CoNiCrAlY, NiCoCrAlYHf and NiCrAlYSi, and has the advantages of wide applicability and ease of implementation.
[0040] Therefore, addressing the challenges of repairing degraded MCrAlY high-temperature protective coatings during service, such as the difficulty of the protective process (chemical method), complex operation involving interface contamination during recoating (sandblasting method), environmental pollution, and uncontrollable damage to the substrate, the thermal barrier coating repair method provided in this invention achieves controllability in the removal process of degraded MCrAlY coatings, precise control of coating thinning thickness, and advantages such as no damage to the substrate, simple operation, and no environmental pollution. Furthermore, this invention, through evaluation of the degraded MCrAlY coating state (composition, thickness), employs multiple solutions for coatings in different states. The performance of the repaired coating is comparable to the original design, exhibiting low cost, simple implementation process, and stable operation, making it suitable for engineering applications.
[0041] refer to Figure 2 As shown, in some specific embodiments, the method for repairing the thermal barrier coating mainly includes the following steps: S10. Remove the ceramic layer. As an example, high-pressure water is used to remove the ceramic layer.
[0042] S20. Assess the degradation status of the adhesive layer to be repaired. As an example, assess the degradation status of the MCrAlY adhesive layer.
[0043] S30. Determine the repair method for the adhesive layer to be repaired based on the evaluation results; that is, design the target MCrAlY adhesive layer.
[0044] S40 and MCrAlY adhesive layers can be controlled to be removed and re-prepared. For example, when it is necessary to repair the adhesive layer to be repaired, the adhesive layer to be repaired of a preset thickness is removed by force-controlled grinding, and then an adhesive layer of a preset thickness is deposited to form the target adhesive layer.
[0045] S50, Ceramic layer preparation; that is, forming a ceramic layer on the surface of the target adhesive layer.
[0046] Therefore, the thermal barrier coating repair method and thermal barrier coating provided in this embodiment can be mainly applied to the repair of thermal barrier coatings and the reuse of turbine blades after service in aero-engines or gas turbines. This repair method is a method for repairing thermal barrier coatings with an MCrAlY binder layer after service. By assessing the state of the MCrAlY binder layer and controlling its removal, and based on the composition of the binder layer before degradation, the composition and thickness of the recoated MCrAlY layer are designed to prepare a thermal barrier coating with a composition similar to and performance identical to the original MCrAlY binder layer. This avoids the problems of removal or protection difficulties, interface inclusions, and substrate damage that exist in traditional methods that completely remove the binder layer. The repair method in this embodiment has the characteristics of low cost, no damage to the blade substrate, and stable coating quality.
[0047] This invention provides a method for repairing thermal barrier coatings with an MCrAlY binder layer after degradation. Specifically, after removing the ceramic layer using high-pressure water jetting, the method focuses on the controllable removal of the MCrAlY binder layer and the restoration of its antioxidant properties. In particular, force-controlled grinding is used to controllably remove the degraded MCrAlY binder layer. Then, using two targets—the original MCrAlY composition and an optimized AlNiY with high Al and Y content—as raw materials, multi-arc ion plating is employed to prepare the desired MCrAlY composition. Vacuum heat treatment is then used to obtain a recoated MCrAlY binder layer with the target composition and properties. This method primarily addresses the coating repair problem of aero-engine or gas turbine blades after service. The main steps include: high-pressure water removal of the ceramic layer; assessment of the MCrAlY binder layer degradation status; design of the target MCrAlY binder layer; controllable removal of the MCrAlY binder layer and re-preparation of the MCrAlY binder layer; and preparation of the ceramic layer. Based on this, the provided method for repairing thermal barrier coatings with MCrAlY bonding layers after service avoids the problems of high control difficulty, interface inclusion, and risk of damage to the substrate that occur when using traditional methods (such as sandblasting and chemical removal) to remove MCrAlY in the thermal barrier coating repair process. It has the advantages of low cost and stable coating quality.
[0048] In the repair method of this embodiment, a thermal barrier coating to be repaired is first provided. The thermal barrier coating to be repaired includes a substrate, and a bonding layer and a ceramic layer disposed on the substrate. The bonding layer to be repaired can be, for example, an MCrAlY bonding layer after service. This method is mainly for the removal and recoating of the thermal barrier coating of turbine blades with MCrAlY as the bonding layer after service.
[0049] Specifically, in step S10, removing the ceramic layer includes removing the ceramic layer by using a high-pressure water jet.
[0050] In this embodiment, after removing the ceramic layer and before assessing the degradation status of the adhesive layer to be repaired, a surface treatment step for the adhesive layer to be repaired is included. As an example, this step S10 may include: high-pressure water jet removal of the ceramic layer and surface treatment of the adhesive layer.
[0051] In some embodiments, the operating conditions for the high-pressure water jet include a pressure of 100 MPa to 300 MPa and a distance of 10 mm to 30 mm between the nozzle and the thermal barrier coating. For example, the pressure can be 150 MPa, 200 MPa, 250 MPa, 300 MPa, etc., and the distance can be 10 mm, 15 mm, 20 mm, 25 mm, 30 mm, etc.
[0052] In some embodiments, the surface treatment includes: sandblasting and cleaning the surface of the adhesive layer to be repaired to remove the thermally grown oxide layer (TGO layer) on the surface of the adhesive layer to be repaired. The sandblasting medium has a mesh size of 150-300 mesh and a sandblasting pressure of 0.1 MPa-0.2 MPa. For example, the mesh size can be 150 mesh, 200 mesh, 250 mesh, 300 mesh, etc.; the sandblasting pressure can be 0.1 MPa, 0.12 MPa, 0.15 MPa, 0.18 MPa, 0.2 MPa, etc. Optionally, the sandblasting medium can be, but is not limited to, corundum. Optionally, the cleaning treatment can be ultrasonic cleaning.
[0053] For example, step S10, high-pressure water jet removal of the ceramic layer, includes: fixing the turbine blade to be repaired inside the high-pressure water equipment tooling, setting the pressure to 100 MPa to 300 MPa, setting the nozzle distance from the thermal barrier coating to 10 mm to 30 mm, setting the movement trajectory and the angle of the high-pressure water nozzle relative to the blade according to the turbine blade profile characteristics, preferably 80° to 100°, completely removing the ceramic layer of the blade body, ensuring that there is no ceramic layer residue on the surface.
[0054] In this embodiment, the surface treatment of the bonding layer to be repaired, namely the MCrAlY bonding layer, mainly involves removing the TGO layer formed after service by sandblasting. The sandblasting is done with 150-300 mesh (0.1 MPa-0.2 MPa) and the cleaning is carried out with white corundum as the medium.
[0055] For example, the surface treatment includes: wet sandblasting (0.1-0.2 MPa) of the MCrAlY bonding layer with 150-300 mesh white corundum, and ultrasonic cleaning of the turbine blades to ensure that the bonding layer surface is clean and free of TGO residue.
[0056] Therefore, the repair method provided in this embodiment uses high-pressure water jet to remove the ceramic layer on the surface of the turbine blade, which has the characteristics of fast removal efficiency and no damage to the bonding layer and high-temperature alloy substrate, making it suitable for engineering applications.
[0057] In addition, this embodiment performs surface treatment before assessing the degradation status of the adhesive layer to be repaired, which makes the surface of the adhesive layer clean and free of TGO residue, thus ensuring the accuracy of the test results.
[0058] Specifically, in step S20, the assessment of the degradation status of the adhesive layer includes: performing X-ray fluorescence spectroscopy (XRF) analysis on the adhesive layer to be repaired to obtain the XRF data of the MCrAlY adhesive layer, wherein the XRF data contains the content of Al element.
[0059] In this embodiment, non-destructive testing methods such as XRF are used to test and evaluate the composition of the degraded MCrAlY adhesive layer to obtain the content of major elements such as Ni, Co, Cr, and Al on the surface of the adhesive layer after the ceramic layer is removed. Among them, Al is used as the main control quantity as the design benchmark for the composition of the recoated adhesive layer.
[0060] For example, step S20, which evaluates the composition of the MCrAlY adhesive layer, includes: using non-destructive testing methods such as XRF to test and evaluate the composition of the degraded adhesive layer MCrAlY, and obtaining the content of major elements such as Ni, Co, Cr, and Al on the surface of the adhesive layer after removing the ceramic layer, with Al being the main controlled quantity.
[0061] Specifically, in step S30, determining the repair method for the adhesive layer to be repaired based on the evaluation results includes: based on the Al content in the obtained XRF data, if the ratio of the Al content in the adhesive layer to be repaired to the Al content in the adhesive layer before degradation is less than a first threshold, then the adhesive layer to be repaired needs to be repaired; if the ratio of the Al content in the adhesive layer to be repaired to the Al content in the adhesive layer before degradation is greater than or equal to the first threshold, then the adhesive layer to be repaired does not need to be repaired.
[0062] Optionally, the first threshold is determined according to the actual situation; for example, the first threshold may be 90%.
[0063] In step S30 of this embodiment, the target MCrAlY adhesive layer is designed, which can be based on the Al content in the adhesive layer. For example, the Al content in the adhesive layer before degradation is denoted as w0, and the thickness of the adhesive layer before degradation is denoted as h0; the Al content in the adhesive layer to be repaired in the XRF data is denoted as w1; the Al content in the adhesive layer with a preset thickness after redeposition is denoted as w2, and the preset thickness is denoted as h2; when w1 ≥ 90% w0, the adhesive layer to be repaired does not need to be repaired; when 70% w0 ≤ w1 < 90% w0, the adhesive layer to be repaired needs to be repaired, and the following conditions must be met: w2: w0 = 1.1~1.3, h2 = 0.2~0.5h0; when w1 < 70% w0, the adhesive layer to be repaired needs to be repaired, and the following conditions must be met: w2: w0 = 1~1.1, h2 = 0.5~0.8h0.
[0064] It should be understood that the aforementioned pre-degradation adhesive layer mainly refers to the MCrAlY adhesive layer before service, such as the thermal barrier coating that has been prepared but not yet used.
[0065] In this embodiment, in step S30, the target MCrAlY adhesive layer composition design can combine the Al content (w0) and the thickness (h0) of the adhesive layer before degradation. The Al content in the adhesive layer to be repaired obtained in step S20 is also the Al content (w1) on the surface of the adhesive layer. The composition (w2) and thickness (h2) of the MCrAlY adhesive layer to be recoated are calculated, which is also the Al content (w2) and the preset thickness (h2) of the adhesive layer to be redeposited. The content of the remaining Co, Cr and Y elements in the coating remains unchanged in proportion.
[0066] In some cases, when w1 ≥ 90% w0, it is not necessary to apply an additional MCrAlY coating.
[0067] In other cases, when 70%w0≤w1<90%w0, the adhesive layer to be repaired needs to be repaired, and the following conditions must be met: w2: w0 is 1.1~1.3, and the thickness of the MCrAlY surface layer removal and repair (i.e. the preset thickness) h2=0.2~0.5h0.
[0068] In some cases, when w1 < 70% w0, the adhesive layer to be repaired needs to be repaired, and the following conditions must be met: w2: w0 is 1 to 1.1, and the thickness of the MCrAlY surface layer removal and repair (i.e., the preset thickness) h2 = 0.5 to 0.8h0.
[0069] Therefore, based on the above, by designing the composition of the target MCrAlY adhesive layer, the thickness that needs to be removed when the adhesive layer to be repaired needs to be repaired, as well as the element content and thickness of the recoated coating, were obtained.
[0070] Specifically, in step S40, the degraded MCrAlY binder layer is controllably removed and the target MCrAlY binder layer is re-prepared. The force-controlled grinding operation conditions include: The grinding head is made of at least one of the following materials: alumina or silicon carbide. The grinding head has a mesh size of 100 to 3000; preferably 500 to 3000.
[0071] The pressure is 10N to 30N.
[0072] In this embodiment, the degraded MCrAlY coating is removed by a force-controlled grinding method with controllable thickness reduction. The removal thickness is 1 / 5 to 4 / 5 t0. During force-controlled grinding, the grinding head is made of wear-resistant materials such as alumina or silicon carbide, and the mesh size is preferably 500 to 3000 mesh; the pressure is 10N to 30N.
[0073] In step S40, after removing part of the degraded adhesive layer by force-controlled grinding, the target adhesive layer is prepared. The method for re-depositing an adhesive layer of a predetermined thickness includes preparing the adhesive layer using a multi-arc ion plating process.
[0074] Optionally, after forming the target adhesive layer and before forming the ceramic layer, a step of vacuum heat treatment of the target adhesive layer is included.
[0075] In some embodiments, the operating conditions of the multi-arc ion plating process include: the target material includes a primary target and a supplementary target, wherein the mass content of Al in the supplementary target is 80wt% to 90wt%, the mass content of Y is 0.5wt% to 1.5wt%, the arc current of the primary target is 60A to 100A, and the arc current of the supplementary target is 30A to 70A; the substrate bias voltage is -30V to -70V. In some embodiments, the operating conditions for vacuum heat treatment include: a temperature of 850°C to 1050°C, a time of 1 hour to 4 hours, and a vacuum degree of ≤1×10⁻⁶. -2 Pa.
[0076] In this embodiment, a multi-arc ion plating process is used to prepare the target bonding layer. The target material in this multi-arc ion plating includes a primary component target and a supplementary raw material target. For example, the primary component target uses the primary MCrAlY component target as raw material, and includes, but is not limited to, a supplementary raw material target using AlNiY target as supplementary raw material. The AlNiY target contains 80wt%–90wt% Al and 0.5wt%–1.5wt% Y. The MCrAlY arc current is 60A–100A, the AlNiY arc current is 30A–70A, and the substrate bias voltage is -30V to -70V.
[0077] After the multi-arc ion plating process, a vacuum heat treatment is required to coat the bonding layer. This allows the degraded MCrAlY, the recoated MCrAlY, and AlNiY to interdiffuse and form the target MCrAlY bonding layer. The vacuum heat treatment conditions are: temperature 850℃~1050℃, time 1h~4h, and vacuum degree ≤1×10⁻⁶. -2 Pa.
[0078] Therefore, in this embodiment, a multi-arc ion plating process is used to prepare a recoated MCrAlY adhesive layer. The recoated MCrAlY adhesive layer uses an MCrAlY target with the same composition as the original MCrAlY and an AlNiY target with high Al and high Y content as coating raw materials. When preparing the recoated MCrAlY adhesive layer, it is preferable to alternate the MCrAlY target and the AlNiY target. Combined with turbine blade rotation control, the composition distribution and microstructure of the recoated coating are consistent in the thickness direction. Vacuum heat treatment is used to allow interdiffusion between the original MCrAlY layer and the recoated MCrAlY layer, as well as the micro-regions in the recoated MCrAlY layer, to form a recoated MCrAlY adhesive layer with consistent target composition and performance. Preferably, during the preparation of the MCrAlY adhesive layer, the arc current of the MCrAlY target is 70–100 A, the arc current of the AlNiY target is 40–70 A, and the substrate bias voltage is -30 to -70 V; preferably, the ratio of MCrAlY target to AlNiY target is 1:1 to 3:1. The vacuum heat treatment conditions for the MCrAlY adhesive layer are 850℃–1050℃ for 1–4 h, with a vacuum degree ≤1×10⁻⁶. -2 Pa.
[0079] Therefore, the repair method provided in this embodiment is based on the original MCrAlY adhesive layer composition. By testing the composition of the degraded MCrAlY adhesive layer, and using the original MCrAlY and AlNiY target materials as raw materials, the target component MCrAlY is recoated into an adhesive layer through a multi-arc ion plating process. Combined with vacuum heat treatment, a recoated MCrAlY adhesive layer with the target performance is obtained. This method has the advantages of simple preparation process and wide process window.
[0080] In some embodiments, during step S50, the ceramic layer is formed by one or more of atmospheric plasma spraying, electron beam physical vapor deposition, and plasma physical vapor deposition.
[0081] In this embodiment, in step S50, the ceramic layer can be prepared according to the original ceramic layer preparation process. For example, the ceramic layer preparation method includes, but is not limited to, atmospheric plasma spraying, electron beam physical vapor deposition, and plasma physical vapor deposition.
[0082] Accordingly, in some embodiments, a thermal barrier coating is provided, which is repaired using the aforementioned thermal barrier coating repair method.
[0083] It should be understood that all the features and advantages described above regarding the "repair method for thermal barrier coatings" also apply to this "thermal barrier coating," and will not be repeated here.
[0084] The following describes the implementation methods of this application. The implementation methods described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the implementation methods, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents, materials, or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.
[0085] Example 1 I. A 20-40 μm thick bonding layer, such as a NiCrAlYSi coating (Al content w0 of 9-10 wt%), was prepared on the surface of 10 DD5 nickel-based superalloy test pieces (φ18×3 mm) using an arc ion plating process. The preparation parameters are shown in Table 1 below. A 150-200 μm thick ceramic layer, such as a YSZ / GZO composite ceramic layer, was prepared using electron beam physical vapor deposition to form a thermal barrier coating. Five test pieces were selected and subjected to isothermal oxidation treatment at 1100℃ for 200 h to simulate the state of the thermal barrier coating after degradation.
[0086] Table 1. Process parameters for preparing arc ion plating coating
[0087] II. A method for repairing thermal barrier coatings, comprising: S10. High-pressure water jet removal of ceramic layer: Fix the degraded specimen inside the high-pressure water equipment fixture, set the pressure to 150MPa, the nozzle distance to the thermal barrier coating to 10mm, the oscillation speed to 10mm / s, and remove until the ceramic layer is completely removed.
[0088] Figure 3 The image shows a comparison of the cross-sectional morphology of region (a) before and region (b) after the ceramic layer was removed from one of the specimens. From... Figure 3 It can be seen that the ceramic layer has been completely removed, leaving only the TGO layer.
[0089] Evaluation of the degradation status of the S20, NiCrAlYSi bond layer: The ceramic layer thickness test piece was wet-blasted with 220-mesh white corundum at 0.2 MPa pressure to remove the surface TGO layer (until the metallic luster was exposed). XRF analysis of the surface coating composition showed an Al content (w1) of 6.8 wt%.
[0090] S30, Design of the target NiCrAlYSi adhesive layer: The Al content w1 in the degraded NiCrAlYSi coating is about 75% of the design value w0 (9~10 wt%). Within the range of 70% w0≤w1<90% w0, the Al content w2 in the NiCrAlYSi coating is 1.1~1.3 w0, and the thickness (preset thickness) h2 of the MCrAlY surface layer removal and replacement is 10μm.
[0091] Controllable removal and re-preparation of S40, NiCrAlYSi binder layer: 1) Force-controlled grinding: The degraded sample was ground using a force-controlled grinding device to remove the NiCrAlYSi coating, with the thickness reduction controlled at 10 μm. Specific parameters are shown in Table 2 below. The final coating removal thickness was calculated to be approximately 10.2 μm using a micrometer.
[0092] Table 2 Force Control Grinding Process Parameters
[0093] 2) Arc ion plating process: First, the surface layer of the NiCrAlYSi sample was removed by 220-mesh abrasive and then wet-blasted at 0.3 MPa. Next, the sample was ultrasonically cleaned for 10 minutes using deionized water. Then, an arc ion plating process was used to prepare a coating on the sample surface. The ratio of NiCrAlYSi target to AlNiY target was 1:1. The deposition processes for the two targets are shown in Table 3, and the remaining parameters are the same as in Table 1.
[0094] Table 3 Process parameters for repaired arc ion plating coating
[0095] 3) Vacuum heat treatment: The repaired coating was subjected to vacuum heat treatment in a vacuum heat treatment furnace. The heat treatment conditions were as follows: heating rate 5℃ / min, heating to 930℃ and holding for 4 hours, with a vacuum degree of 6.2×10⁻⁶ during the holding process. -3 Pa, then cooled down with the furnace.
[0096] Figure 4 The cross-sectional morphology of the repaired coating (target adhesive layer) provided in the embodiments of the present invention is shown. Figure 4 It can be seen that the repaired NiCrAlYSi coating is tightly bonded to the degraded residual coating, and some interdiffusion has occurred. Meanwhile, the composition of the repaired coating was measured using an electron probe microanalysis device, and compared with the original coating composition, as shown in Table 4. It can be seen that the coating composition before and after repair is basically the same.
[0097] Table 4. Composition of the repaired arc ion plating coating
[0098] Figure 5 The phase structure of the NiCrAlYSi bonding layer before and after repair, as provided in the embodiments of the present invention, is shown. Figure 5 It can be seen that the NiCrAlYSi bonding layer is composed of γ, β and γ' phases before and after repair, and the phase structure is consistent.
[0099] S50, Ceramic Layer Preparation and Performance Testing: A 150–200 μm YSZ / GZO composite thermal barrier coating was prepared using electron beam physical vapor deposition, following the same process as the first deposition. The repaired and original (non-degraded) states were subjected to oxidation treatment at 1100℃ for 100 h according to HB5258 standard. The average oxidation rate curves are shown below. Figure 6 As shown, from Figure 6 It can be seen that the average oxidation rate of the two coating states is similar after 100 hours, and both reach a state of complete oxidation resistance.
[0100] The parts of this invention not described in detail are techniques known to those skilled in the art.
[0101] The basic principles of the present invention have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in the present invention are merely examples and not limitations, and should not be considered as essential features of each embodiment of the present invention. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the present invention to the necessity of employing the aforementioned specific details.
[0102] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. A method for repairing thermal barrier coatings, characterized in that, The repair method includes: A thermal barrier coating to be repaired is provided, the thermal barrier coating to be repaired comprising a substrate, an adhesive layer to be repaired disposed on the substrate, and a ceramic layer; Remove the ceramic layer; The degradation status of the adhesive layer to be repaired is assessed; The repair method for the adhesive layer to be repaired is determined based on the evaluation results. When it is necessary to repair the adhesive layer to be repaired, a preset thickness of the adhesive layer to be repaired is removed by force-controlled grinding, and then an adhesive layer of a preset thickness is deposited to form the target adhesive layer. A ceramic layer is formed on the surface of the target adhesive layer.
2. The method for repairing thermal barrier coatings according to claim 1, characterized in that, The removal of the ceramic layer includes: removing the ceramic layer using a high-pressure water jet method; And / or, after removing the ceramic layer and before assessing the degradation status of the adhesive layer to be repaired, the method further includes a step of surface treatment of the adhesive layer to be repaired.
3. The method for repairing thermal barrier coatings according to claim 2, characterized in that, The operating conditions for the high-pressure water jet include: a pressure of 100MPa to 300MPa and a distance of 10mm to 30mm between the nozzle and the thermal barrier coating. And / or, the surface treatment includes: sandblasting and cleaning the surface of the adhesive layer to be repaired to remove the thermally grown oxide layer on the surface of the adhesive layer to be repaired, wherein the sandblasting medium has a mesh size of 150-300 mesh and the sandblasting pressure is 0.1 MPa-0.2 MPa.
4. The method for repairing thermal barrier coatings according to any one of claims 1 to 3, characterized in that, The adhesive layer to be repaired includes an MCrAlY adhesive layer, wherein M includes at least one or both of nickel and cobalt.
5. The method for repairing thermal barrier coatings according to claim 4, characterized in that, The degradation status assessment of the adhesive layer to be repaired includes: performing X-ray fluorescence spectroscopy analysis on the adhesive layer to be repaired to obtain XRF data of the MCrAlY adhesive layer, wherein the XRF data includes the content of Al element.
6. The method for repairing thermal barrier coatings according to claim 5, characterized in that, The step of determining the repair method for the adhesive layer to be repaired based on the evaluation results includes: Based on the Al content in the obtained XRF data, if the ratio of the Al content in the adhesive layer to be repaired to the Al content in the adhesive layer before degradation is less than a first threshold, then the adhesive layer to be repaired needs to be repaired. When the ratio of the Al content in the adhesive layer to be repaired to the Al content in the adhesive layer before degradation is greater than or equal to a first threshold, then the adhesive layer to be repaired does not need to be repaired.
7. The method for repairing thermal barrier coatings according to claim 6, characterized in that, The Al content in the adhesive layer before degradation is denoted as w0, and the thickness of the adhesive layer before degradation is denoted as h0; The Al content in the adhesive layer to be repaired in the XRF data is denoted as w1; The Al content in the redeposited adhesive layer of a predetermined thickness is denoted as w2, and the predetermined thickness is denoted as h2; When w1≥90%w0, the adhesive layer to be repaired does not need to be repaired. When 70%w0≤w1<90%w0, the adhesive layer to be repaired needs to be repaired, and the following conditions must be met: w2: w0 is 1.1~1.3, h2=0.2~0.5h0; When w1 < 70%w0, the adhesive layer to be repaired needs to be repaired, and the following conditions must be met: w2: w0 is 1 to 1.1, h2 = 0.5 to 0.8h0.
8. The method for repairing thermal barrier coatings according to claim 1, characterized in that, The operating conditions for force-controlled polishing include at least the following: The grinding head is made of at least one of alumina or silicon carbide; The grinding head has a mesh size ranging from 100 to 3000. The pressure is 10N to 30N.
9. The method for repairing thermal barrier coatings according to claim 1, characterized in that, The method of redepositing the adhesive layer of a predetermined thickness includes: The adhesive layer was prepared using a multi-arc ion plating process; And / or, after forming the target adhesive layer and before forming the ceramic layer, the step of performing vacuum heat treatment on the target adhesive layer is further included.
10. The method for repairing thermal barrier coatings according to claim 9, characterized in that, The operating conditions for the multi-arc ion plating process include: The target material includes a raw material target material and a supplementary raw material target material, wherein the mass content of Al in the supplementary raw material target material is 80% to 90%, and the mass content of Y is 0.5% to 1.5%. The arc current of the original component target is 60A to 100A, and the arc current of the supplementary raw material target is 30A to 70A. The substrate bias voltage is -30V to -70V; And / or, the operating conditions for the vacuum heat treatment include: a temperature of 850℃~1050℃, a time of 1h~4h, and a vacuum degree of ≤1×10 -2 Pa.
11. The method for repairing thermal barrier coatings according to any one of claims 1 to 3, 5 to 10, characterized in that, The ceramic layer can be formed by one or more of atmospheric plasma spraying, electron beam physical vapor deposition, and plasma physical vapor deposition.
12. A thermal barrier coating, characterized in that, The thermal barrier coating is repaired using the thermal barrier coating repair method according to any one of claims 1 to 11.