Tantalate / YSZ double-ceramic-layer thermal barrier coating thickness optimization method

Abstract

The invention belongs to the technical field of coating optimization, and particularly relates to a tantalate / YSZ (Yttria Stabilized Zirconia) double-ceramic-layer thermal barrier coating thickness optimization method which comprises the following steps: establishing double-ceramic-layer thermal barrier coating models with different layer thicknesses; performing finite element analysis on the model to obtain residual stress and effective thermal conductivity; drawing an axial stress curve, a first principal stress curve and an effective thermal conductivity curve based on the residual stress and the thermal conductivity; and determining an optimal optimization area according to the curve, and selecting the most adaptive coating thickness in the actual process from the optimal optimization area. The thickness control problem in the actual preparation process of the double-ceramic-layer thermal barrier coating can be solved.

Description

Technical Field

[0001] The invention belongs to the technical field of coating optimization, and in particular relates to a method for optimizing the thickness of a tantalate / YSZ double-ceramic layer thermal barrier coating. Background Art

[0002] Thermal barrier coating is an important inorganic coating material, which is widely used on high-temperature alloy blades of aircraft engines and ground gas turbines. It has multiple functions such as high-temperature heat insulation, oxidation resistance, corrosion resistance, and wear resistance. As the inlet temperature of the gas turbine turbine end continues to rise, the requirements for its thermal efficiency are also increasing. However, single-crystal nickel-based high-temperature alloys (maximum operating temperature does not exceed 1150°C) and film cooling technology have reached their limits. Therefore, the development of a new type of thermal barrier coating with higher heat resistance, stronger thermal insulation performance, and longer service life has become a key issue faced in achieving gas turbine performance improvement.

[0003] Double ceramic layer thermal barrier coatings (DCLTBCs) are one of the important research directions of thermal barrier coatings. It deposits a ceramic layer with higher thermal stability and lower thermal conductivity on the traditional thermal barrier coating, which has a significant effect on increasing the use temperature and extending the life of the thermal barrier coating. Double ceramic layer thermal barrier coatings use the complementary performance advantages of two ceramic layers, with a ceramic material with higher use temperature and lower thermal conductivity as the surface layer and a ceramic material with higher thermal expansion coefficient and higher strain tolerance as the second layer, thereby achieving effective protection of the base alloy material.

[0004] However, most current testing methods mainly analyze and calculate the residual stress and thermal insulation effect of the coating separately. This method cannot effectively optimize and improve the overall performance of the coating. Therefore, developing an optimization method that can simultaneously consider residual stress and thermal insulation performance is of great significance for further improving the performance of dual-ceramic layer thermal barrier coatings. Summary of the invention

[0005] The present invention provides a method for optimizing the thickness of a tantalate / YSZ double-ceramic layer thermal barrier coating, which solves the problem of thickness control in the actual preparation process of the double-ceramic layer thermal barrier coating.

[0006] The present invention provides a method for optimizing the thickness of a tantalate / YSZ dual-ceramic layer thermal barrier coating, comprising: Modeling of thermal barrier coatings with dual ceramic layers and different layer thicknesses; Performing finite element analysis on the model to obtain residual stress and effective thermal conductivity; Based on the residual stress and the thermal conductivity, an axial stress curve, a first principal stress curve and an effective thermal conductivity curve are drawn; the best optimization region is determined according to the curves, and the coating thickness that is most suitable in the actual process is selected from the best optimization region.

[0007] As an optional embodiment, the double ceramic layer thermal barrier coating model consists of a rare earth yttrium tantalate ceramic top layer, an 8% wt. yttria partially stabilized zirconia ceramic bottom layer, a NiCoCrAlY bonding layer and a high-temperature nickel-based alloy substrate, and the rare earth yttrium tantalate ceramic top layer is a YTaO4 layer or a Y3TaO7 layer.

[0008] As an optional implementation, the finite element analysis includes residual stress analysis and thermal insulation analysis to obtain residual stress distribution data and temperature field change data accordingly.

[0009] As an optional implementation, the residual stress analysis and / or the thermal insulation analysis adopts a finite element mesh type of a four-node quadrilateral axisymmetric reduced integration unit.

[0010] As an optional implementation, the condition state set during residual stress analysis is: Setting the overall temperature of the spraying process to a first preset temperature; Setting the coating system to have natural heat convection with room temperature air, and the convection heat transfer coefficient is a first preset heat transfer coefficient; Setting the atmospheric temperature to a first preset atmospheric temperature; Set the cooling time of the sample after preparation to the first preset cooling time.

[0011] As an optional implementation, the condition state set during the thermal insulation analysis is: Setting the upper surface temperature of the model to rise evenly from room temperature to a second preset temperature within two minutes; Setting the heat transfer coefficient between the bottom and the environment to the second preset heat transfer coefficient; Set the hold time to the first preset hold time.

[0012] As an optional implementation, the thermal insulation analysis includes: A corresponding temperature field is set based on the finite element model, wherein the temperature field at least includes that the upper surface temperature and the lower surface temperature of the model reach a thermal equilibrium state, and the left and right boundaries of the model are both in an adiabatic state; Based on the temperature field, the effective thermal conductivity is obtained.

[0013] As an optional implementation manner, obtaining the effective thermal conductivity based on the temperature field includes: Get the ambient temperature T c ; Get the model thickness H; Obtain the convection heat transfer coefficient h between the bottom of the finite element model and the environment; Get the surface temperature T of the ceramic layer a and the lower surface temperature of the ceramic layer T b ; Based on ambient temperature T c , model thickness H, convective heat transfer coefficient h between the bottom of the finite element model and the environment, and the upper surface temperature T of the ceramic layer a and the lower surface temperature of the ceramic layer T b , and the effective thermal conductivity k is obtained eff :

[0014] As an optional implementation, the best optimization region is determined by a region between an intersection point of the effective thermal conductivity curve and the first principal stress curve and an intersection point of the effective thermal conductivity curve and the axial stress curve.

[0015] As an optional implementation manner, the YSZ layer thickness corresponding to the best optimized area ranges from 190 μm to 280 μm.

[0016] The present invention achieves both the reduction of residual stress and the improvement of thermal insulation performance of the thermal barrier coating by modeling the double-ceramic layer thermal barrier coating, calculating the residual stress of the double-ceramic layer thermal barrier coating after spraying and cooling, calculating the thermal insulation behavior of the double-ceramic layer thermal barrier coating, and collaboratively optimizing the coating thickness based on the residual stress and the thermal insulation effect, thereby providing certain theoretical guidance for the optimization and design of the preparation process of the double-ceramic layer thermal barrier coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic flow chart of a method for optimizing thickness of a tantalate / YSZ dual-ceramic layer thermal barrier coating in one embodiment of the present application is shown.

[0018] Figure 2 A schematic diagram of a finite element model of a tantalate / YSZ dual-ceramic layer thermal barrier coating in an embodiment of the present application is shown.

[0019] Figure 3 A schematic diagram of heat transfer and convection of a tantalate / YSZ dual-ceramic layer thermal barrier coating model in one embodiment of the present application is shown.

[0020] Figure 3 (a) shows a schematic diagram of the residual stress model after spray cooling in one embodiment of the present application.

[0021] Figure 3 (b) shows a schematic diagram of the thermal insulation behavior calculation model in one embodiment of the present application.

[0022] Figure 4The stress curves of coatings with different thickness ratios under the conditions of simulated spray cooling in one embodiment of the present application are shown.

[0023] Figure 4 (a) shows the axial stress curve of coatings with different thickness ratios in one embodiment of the present application.

[0024] Figure 4 (b) shows the first principal stress curve of coatings with different thickness ratios in one embodiment of the present application.

[0025] Figure 5 The thermal insulation curves of coatings with different thickness ratios under the condition of simulating the thermal insulation process in one embodiment of the present application are shown.

[0026] Figure 5 (a) shows a schematic diagram of the thermal insulation temperature difference of coatings with different thickness ratios in one embodiment of the present application.

[0027] Figure 5 (b) shows the effective thermal conductivity curve of coatings with different thickness ratios in one embodiment of the present application.

[0028] Figure 6 A schematic diagram of thickness optimization of coatings with different thickness ratios in one embodiment of the present application is shown. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0030] Tantalate has a ferroelastic phase transition similar to that of YSZ. Under certain conditions, the movement and flipping of domain walls will hinder the expansion of cracks to a certain extent, thereby improving its fracture toughness. In addition, tantalate has good high-temperature stability, sintering resistance, and low thermal conductivity. Therefore, it is expected to be a candidate material for the next generation of thermal barrier coatings. The composite preparation of YSZ and tantalate into a double ceramic layer thermal barrier coating can not only achieve high thermal insulation, but also give full play to the excellent properties of YSZ coating below 1200°C. However, the thickness control of the actual coating preparation is based on experience, and the thickness control is completely artificial. The present invention provides a method for controlling the thickness of a tantalate / YSZ double ceramic layer thermal barrier coating. Although the results obtained are partially dependent on the finite element calculation results, it is precisely with the help of software and methods that data-driven and material high-throughput calculations are realized, and finally the thickness optimization of the tantalate / YSZ double ceramic layer is realized, which subverts the traditional experience-driven concept of coating preparation and provides theoretical support and reference for the preparation of high-performance coatings.

[0031] The premise for the implementation of the present invention requires that the entire thermal barrier coating is uniform and continuous inside, without pores, cracks and other defects that affect the performance of the coating; the substrate and the surfaces of each deposited coating are smooth, the layers are firmly bonded, and there is no horizontal displacement and vertical separation; the influence of the thermally grown oxide layer inside the coating during the heating process is not considered; there is no residual stress in the initial state of the coating; the thermal radiation of the coating surface is ignored, and the coating surface transfers heat to the surrounding medium by convection, and the interface thermal resistance and the creep effect of the coating as a whole are not considered.

[0032] In the present invention, the residual stress generated during the spraying preparation process is the initial condition of the stress distribution in the thermal barrier coating system at the beginning of thermal cycle loading, so the sprayed residual stress is the main driving force for crack nucleation and expansion in the thermal barrier coating system. The thermal insulation performance of the coating is directly related to the operating temperature of the high-temperature alloy component, and also affects the service life of the thermal barrier coating. For a given coating material, the thermal insulation performance of the coating increases with the increase of the coating thickness, but the thermal mismatch stress inside the coating (including the interface) may also increase accordingly. Therefore, a balance needs to be achieved between the thermal insulation performance and the overall residual stress level.

[0033] In view of this, if Figure 1 As shown, the present invention provides a method for optimizing the thickness of a tantalate / YSZ dual-ceramic layer thermal barrier coating, comprising the following steps.

[0034] Step S100: establishing a dual-ceramic-layer thermal barrier coating model with different layer thicknesses.

[0035] Step S200: performing finite element analysis on the model to obtain residual stress and effective thermal conductivity; specifically, in the present invention, residual stress analysis and thermal insulation analysis of the sprayed coating are performed on the YTO / YSZ dual-ceramic layer thermal barrier coating of different optimized test groups through finite element analysis software to obtain the residual stress distribution and temperature field changes of the coating under preset working conditions (including initial conditions and boundary conditions).

[0036] Step S300: drawing an axial stress curve, a first principal stress curve and an effective thermal conductivity curve based on the residual stress and the thermal conductivity;

[0037] Step S400: determining the best optimization region according to the curve, and selecting the coating thickness that is most suitable in the actual process from the best optimization region.

[0038] In the present invention, based on the criteria of low residual stress and good thermal insulation performance of the coating, the thickness of the coating is jointly optimized, the axial stress curve, the first principal stress curve and the effective thermal conductivity curve of different thicknesses are plotted and integrated for analysis to obtain the best optimization area, and the most suitable coating thickness in the actual process is selected from the area.

[0039] In one embodiment of the present invention, Figure 2 As shown, the double ceramic layer thermal barrier coating model consists of a rare earth yttrium tantalate ceramic top layer (YTO layer), an 8% wt. yttria partially stabilized zirconia ceramic bottom layer (YSZ layer), a NiCoCrAlY bonding layer (BC layer) and a high temperature nickel-based alloy substrate (SUB layer).

[0040] Specifically, the double ceramic layer thermal barrier coating model consists of a rare earth yttrium tantalate ceramic top layer (YTaO4 layer or Y3TaO7 layer), an 8%w yttria partially stabilized zirconia ceramic bottom layer (YSZ layer), a NiCoCrA1Y bonding layer (BC layer) and a high temperature nickel-based alloy base (SUB layer).

[0041] Among them, the advantage of selecting ceramic layer materials is that on the one hand, due to the lower thermal conductivity of the coating, the thermal insulation performance of the thermal barrier coating as a whole is improved compared with the traditional YSZ thermal barrier coating; on the other hand, because YSZ (layer) acts as a stress buffer layer, it can effectively reduce the overall thermal stress inside the coating and alleviate the problem of premature failure of the coating interface due to excessive stress.

[0042] In an application scenario of the present invention, 1 / 2 of the plane where the central axis of the cylinder and the diameter of the bottom surface of the cylinder are located is selected, and then parameters are assigned to each layer respectively, and the boundary conditions and conditional assumptions of the model are set to realize the application of the material database.

[0043] Exemplarily, in the model, the width of the high-temperature alloy substrate is set to 10 mm, the substrate thickness is set to 6 mm, the thickness of the bonding layer is set to 100 μm, and the total thickness of the ceramic layer is set to 400 μm. While ensuring that the total thickness of the ceramic layer remains unchanged, the thickness ratio of the YSZ layer and the YTO layer is changed.

[0044] In one embodiment of the present invention, a dual-ceramic layer thermal barrier coating with different layer thicknesses is established as a high-throughput optimization test group, and high-throughput calculation and analysis of sprayed coating stress and thermal insulation are performed on the dual-ceramic layer thermal barrier coating of each thickness optimization experimental group. As shown in Table 1 below, 9 test comparison groups for thickness optimization of YTO / YSZ dual-ceramic layer thermal barrier coatings are set.

[0045] Table 1 YTO / YSZ dual ceramic layer thermal barrier coating optimization test group

[0046] like Figure 3 As shown, in one embodiment of the present invention, the finite element analysis includes residual stress analysis and thermal insulation analysis to obtain residual stress distribution data and temperature field change data accordingly.

[0047] In one embodiment of the present invention, the residual stress analysis and / or the thermal insulation analysis adopts a finite element mesh type of a four-node quadrilateral axisymmetric reduced integration (CAX4T) unit.

[0048] like Figure 3 As shown in (a), in one embodiment of the present invention, the condition state set during the residual stress analysis is: Setting the overall temperature of the spraying process to a first preset temperature; Setting the coating system to have natural heat convection with room temperature air, and the convection heat transfer coefficient is a first preset heat transfer coefficient; Setting the atmospheric temperature to a first preset atmospheric temperature; Set the cooling time of the sample after preparation to the first preset cooling time.

[0049] Specifically, in the residual stress calculation process of the double-ceramic layer thermal barrier coating, the overall temperature of the spraying process is set to the spraying temperature of the actual process, the coating system undergoes natural heat convection with room temperature air, and the sample is cooled for a sufficiently long time after preparation, in order to ensure that the entire coating core and surface sides are in a thermal equilibrium state.

[0050] In an application scenario of the present invention, the residual stress of the double ceramic layer thermal barrier coating model after spray cooling is calculated. The finite element mesh type of the four-node quadrilateral axisymmetric reduced integration (CAX4T) unit is selected, and the overall temperature of the spraying process is set at 427°C. Spraying is performed on the substrate, and the coating system undergoes natural heat convection with room temperature air. The convection heat transfer coefficient is 8W / (m 2 ·K), the atmospheric temperature was set to 25°C, and the sample was cooled for 14400s after preparation.

[0051] like Figure 4 , Figure 4 (a) and Figure 4 As shown in (b), the axial stress and the first principal stress peak data of coatings with different thickness ratios are obtained in the obtained stress field distribution and are plotted into curves respectively.

[0052] like Figure 3 (b), in one embodiment of the present invention, the condition state set during the thermal insulation analysis is: Setting the upper surface temperature of the model to rise evenly from room temperature to a second preset temperature within two minutes; Setting the heat transfer coefficient between the bottom and the environment to the second preset heat transfer coefficient; Set the hold time to the first preset hold time.

[0053] In an application scenario of the present invention, the calculation process of simulating the thermal insulation behavior of the double ceramic layer thermal barrier coating includes: under the condition of considering only heat conduction and heat convection heat transfer, the thermal insulation process of the thermal barrier coating goes through two stages of heating and heat preservation heat balance, the finite element mesh type of the four-node linear axisymmetric heat transfer quadrilateral (DCAX4) unit is selected, the upper surface temperature of the model is set to rise uniformly from room temperature 25°C to 1300°C within two minutes, and the heat transfer coefficient between the bottom and the environment is set to 400W / (m 2 ·K), the holding time is 12 minutes to ensure that the upper surface temperature and the bottom temperature fully reach the thermal equilibrium state.

[0054] In one embodiment of the present invention, the thermal insulation analysis includes: Select the finite element mesh type of four-node linear axisymmetric heat transfer quadrilateral (DCAX4) element as the finite element model; A corresponding temperature field is set based on the finite element model, wherein the temperature field at least includes that the upper surface temperature and the lower surface temperature of the model reach a thermal equilibrium state, and the left and right boundaries of the model are both in an adiabatic state; Based on the temperature field, the effective thermal conductivity is obtained.

[0055] Among them, in the present invention, the calculation process of the thermal insulation behavior of the double-ceramic layer thermal barrier coating is divided into a heating stage and a heat preservation thermal equilibrium stage. The upper surface of the model is set to rise to a certain temperature, and the heat is preserved for a sufficiently long time through heat transfer and environmental convection, in order to ensure that the upper surface temperature and the bottom temperature fully reach a thermal equilibrium state.

[0056] In one embodiment of the present invention, obtaining effective thermal conductivity based on the temperature field includes: Get the ambient temperature T c ; Get the model thickness H; Obtain the convection heat transfer coefficient h between the bottom of the finite element model and the environment; Get the surface temperature T of the ceramic layer a and the lower surface temperature of the ceramic layer T b ; Based on ambient temperature T c , model thickness H, convective heat transfer coefficient h between the bottom of the finite element model and the environment, and the upper surface temperature T of the ceramic layer a and the lower surface temperature of the ceramic layer T b , and the effective thermal conductivity k is obtained eff :

[0057] Specifically, since the left and right boundaries of the model are in adiabatic, the heat flux from the top of the unit to the bottom of the unit is equal to the heat exchange between the bottom and the environment: Among them, Q in is the heat flux flowing into the unit, Q out is the heat flux out of the unit.

[0058] Therefore, the effective thermal conductivity of the coating (K eff )The formula is:

[0059] like Figure 5 , Figure 5 (a) and Figure 5 As shown in (b), the effective thermal conductivity data of the coating is obtained by combining the insulation temperature difference ΔT between the surface of the coating and the back of the substrate with the effective thermal conductivity formula and is plotted as a curve.

[0060] like Figure 6 As shown, in one embodiment of the present invention, the best optimization area is determined by the area between the intersection of the effective thermal conductivity curve and the first principal stress curve and the intersection of the effective thermal conductivity curve and the axial stress curve. Exemplarily, the YSZ layer thickness range corresponding to the best optimization area is 190μm to 280μm.

[0061] The present invention adopts the optimization target interval method to obtain the best optimization result of the dual-ceramic layer thermal barrier coating. In addition, the present invention preferably only records the peak data of the axial stress and the first principal stress of the dual-ceramic layer thermal barrier coating with different thickness ratios. The reason is that the axial stress is more likely to cause delamination and peeling failure at the interface, and the peak position of the first principal stress may become the starting point of the crack. Comprehensive comparison, the thickness optimization of the coating should focus on minimizing the peak values ​​of the axial stress and the first principal stress to reduce the risk of crack formation and propagation.

[0062] The present invention optimizes the thickness of the coating based on residual stress and thermal insulation performance, and plots and integrates the axial stress curve, the first principal stress curve and the effective thermal conductivity curve of different thicknesses. Figure 6 , the effective thermal conductivity curve intersects the first principal stress curve at point A. Figure 6 It can be seen that the left side of point A satisfies the condition that the effective thermal conductivity is low, but the first principal stress is high. On the contrary, the right side of point A satisfies the condition that the stress is small, but the effective thermal conductivity is high. Therefore, point A is determined to be the critical point of the effective thermal conductivity and the first principal stress. Similarly, the effective thermal conductivity curve intersects the axial stress curve at point B, which is the critical point of the effective thermal conductivity and the axial stress.

[0063] In order to optimize the three variables in a coordinated manner, the thickness range is selected to be between the two critical points, namely, the S zone, according to the optimization goal. Figure 6It can be obtained that the corresponding YSZ thickness in the S region ranges from 190μm to 280μm, while the YSZ layer thickness in the simulation group is 250μm and the YTO layer thickness is 150μm, which is in the middle of this region.

[0064] The present invention plots the axial stress, the first principal stress and the effective thermal conductivity curves, selects the overlapping area as the best optimization interval, further considers that in the actual process, each time spraying, the thickness is usually within the preset spraying thickness, and selects a suitable value as the best optimization thickness.

[0065] In order to make the subsequent spraying convenient and reasonable, considering that in the actual process, the preset spraying thickness is set at about 20μm for each spraying, the YSZ layer thickness of 260μm and the YTO layer thickness of 140μm are selected as reasonable thickness optimization results.

[0066] The present invention adopts thermomechanical coupling finite element software to realize the thickness optimization method of YTaO4 (YTO) / YSZ dual ceramic layer thermal barrier coating, which has the characteristics of strong adaptability, great flexibility, high calculation accuracy and low cost. The dual ceramic layer thermal barrier coating system is modeled based on ABAQUS commercial finite element software. In the model, the total thickness of the high-temperature alloy substrate, bonding layer and ceramic layer is set unchanged, and the thickness ratio of the YSZ layer and the YTO layer is changed. The distribution of the stress field after spray cooling of the coating under different thickness ratios and the change of the temperature field after experiencing the two stages of heating and heat preservation thermal equilibrium are simulated respectively, and the stress and thermal insulation results of the coating under different thickness ratios are recorded. Based on the analysis of the stress distribution results, the axial stress and the first principal stress are selected as the target variables for thickness optimization. The effective thermal conductivity of the coating is calculated according to the heat transfer formula and the thermal insulation temperature difference, and it is used as the thermal insulation variable for thickness optimization.

[0067] Based on the change curves of the three factors with different thickness ratios, the performance of the YTO / YSZ dual-ceramic layer thermal barrier coating is jointly evaluated, and finally the thickness optimization range is obtained. According to the actual spraying process, a more reasonable thickness optimization result is selected from the optimization area to guide the thickness control of the actual dual-ceramic layer thermal spray coating. While ensuring the stability of the coating structure, the best thermal insulation effect can be obtained, which helps to improve the heat resistance temperature and extend the service life of the thermal barrier coating, thereby improving the overall performance and efficiency of the gas turbine.

[0068] It should also be understood that the terms used in this disclosure are only for the purpose of describing specific embodiments and are not intended to limit the disclosure. As used in this disclosure and claims, the singular forms of "a", "an", and "the" are intended to include the plural forms unless the context clearly indicates otherwise. It should also be further understood that the term "and / or" used in this disclosure and claims refers to any combination of one or more of the associated listed items and all possible combinations, including these combinations.

[0069] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, segment or portion of code that includes one or more executable instructions for implementing the steps of a specific logical function or process, and the scope of the preferred embodiments of the present invention includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present invention belong.

[0070] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in terms of function in the above description. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0071] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for optimizing the thickness of a tantalate / YSZ dual-ceramic thermal barrier coating, characterized in that: include: Modeling of thermal barrier coatings with dual ceramic layers and different layer thicknesses; Performing finite element analysis on the model to obtain residual stress and effective thermal conductivity; Based on the residual stress and the thermal conductivity, an axial stress curve, a first principal stress curve and an effective thermal conductivity curve are plotted; The best optimization region is determined according to the curve, and the coating thickness that is most suitable in the actual process is selected from the best optimization region.

2. The method for optimizing the thickness of a tantalate / YSZ dual-ceramic thermal barrier coating according to claim 1, characterized in that: The double ceramic layer thermal barrier coating model consists of a rare earth yttrium tantalate ceramic top layer, an 8%wt. yttria partially stabilized zirconia ceramic bottom layer, a NiCoCrAlY bonding layer and a high-temperature nickel-based alloy substrate, wherein the rare earth yttrium tantalate ceramic top layer is a YTaO4 layer or a Y3TaO7 layer.

3. The method for optimizing the thickness of a tantalate / YSZ dual-ceramic thermal barrier coating according to claim 1 or 2, characterized in that: The finite element analysis includes residual stress analysis and thermal insulation analysis to obtain residual stress distribution data and temperature field change data accordingly.

4. The method for optimizing the thickness of a tantalate / YSZ dual-ceramic thermal barrier coating according to claim 3, characterized in that: The residual stress analysis and / or the thermal insulation analysis adopts a finite element mesh type of a four-node quadrilateral axisymmetric reduced integration unit.

5. The method for optimizing the thickness of a tantalate / YSZ dual-ceramic thermal barrier coating according to claim 3 or 4, characterized in that: The conditions set during residual stress analysis are: Setting the overall temperature of the spraying process to a first preset temperature; Setting the coating system to have natural heat convection with room temperature air, and the convection heat transfer coefficient is a first preset heat transfer coefficient; Setting the atmospheric temperature to a first preset atmospheric temperature; Set the cooling time of the sample after preparation to the first preset cooling time.

6. The method for optimizing thickness of a tantalate / YSZ dual-ceramic thermal barrier coating according to any one of claims 3 to 5, characterized in that: The conditions set in thermal insulation analysis are: Setting the upper surface temperature of the model to rise evenly from room temperature to a second preset temperature within two minutes; Setting the heat transfer coefficient between the bottom and the environment to the second preset heat transfer coefficient; Set the hold time to the first preset hold time.

7. The method for optimizing thickness of tantalate / YSZ dual ceramic layer thermal barrier coating according to any one of claims 3 to 6, characterized in that: The thermal insulation analysis includes: A corresponding temperature field is set based on the finite element model, wherein the temperature field at least includes that the upper surface temperature and the lower surface temperature of the model reach a thermal equilibrium state, and the left and right boundaries of the model are both in an adiabatic state; Based on the temperature field, the effective thermal conductivity is obtained.

8. The method for optimizing thickness of tantalate / YSZ dual ceramic layer thermal barrier coating according to claim 7, characterized in that: The obtaining of effective thermal conductivity based on the temperature field includes: Get the ambient temperature T c ; Get the model thickness H; Obtain the convection heat transfer coefficient h between the bottom of the finite element model and the environment; Get the surface temperature T of the ceramic layer a and the lower surface temperature of the ceramic layer T b ; Based on ambient temperature T c , model thickness H, convective heat transfer coefficient h between the bottom of the finite element model and the environment, and the upper surface temperature T of the ceramic layer a and the lower surface temperature of the ceramic layer T b , and the effective thermal conductivity k is obtained eff :

9. The method for optimizing thickness of a tantalate / YSZ dual-ceramic thermal barrier coating according to any one of claims 1 to 8, characterized in that: The best optimization region is determined by a region between an intersection point of the effective thermal conductivity curve and the first principal stress curve and an intersection point of the effective thermal conductivity curve and the axial stress curve.

10. The method for optimizing thickness of tantalate / YSZ dual ceramic layer thermal barrier coating according to claim 9, characterized in that: The YSZ layer thickness range corresponding to the best optimized area is 190 μm to 280 μm.

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