Long-life ultrahigh-temperature thermal barrier coating and preparation method thereof

Abstract

The invention relates to the technical field of high-temperature thermal protection coatings, in particular to a long-service-life ultra-high-temperature thermal barrier coating and a preparation method thereof, and solves the technical problem that in the prior art, the thermal cycle life of a thermal barrier coating in a high-temperature environment is insufficient. The long-service-life ultra-high-temperature thermal barrier coating comprises a CoNiCrAlY metal bonding layer, a YSZ transition layer and a BMT ceramic layer which are sequentially deposited from bottom to top; wherein the BMT ceramic layer is made of a BMT liquid material. The preparation method comprises the following steps: firstly, carrying out cleaning pretreatment on a substrate, and then sequentially preparing a metal bonding layer and a transition layer on the surface of the high-temperature alloy substrate by adopting an APS technology; and finally, preparing the BMT ceramic layer on the surface of the YSZ transition layer by adopting a suspension plasma spraying technology SPS. The BMT ceramic layer prepared through SPS has a columnar crystal-like microstructure, the strain tolerance of the coating can be remarkably increased, and thermal stress accumulation in thermal circulation of the coating is reduced. The thermal barrier coating prepared through the method has excellent thermal cycle performance and good bonding strength and heat insulation performance.

Description

Technical Field

[0001] The present invention relates to the technical field of high-temperature thermal protective coatings, and in particular to a long-life ultra-high-temperature thermal barrier coating and a preparation method thereof. Background Art

[0002] Thermal barrier coating is a high-temperature resistant and highly heat-insulating film coated on the surface of high-temperature alloy. It can isolate the core components of the hot end of the gas turbine engine from the high-temperature medium, avoid direct contact between the components and the high-temperature medium, and prevent them from corrosion, high-temperature oxidation and other failure behaviors caused by long-term service at high temperatures, thereby effectively improving the temperature resistance of the hot end components of the gas turbine engine, thereby improving the thrust-to-weight ratio and working efficiency of the gas turbine engine.

[0003] A typical thermal barrier coating consists of a two-layer structure: a metal bonding layer and a ceramic layer. The main function of the metal bonding layer is to resist high-temperature oxidation and alleviate the thermal mismatch between the ceramic layer and the substrate, and the function of the ceramic layer is mainly to provide good thermal insulation performance.

[0004] Yttria partially stabilized zirconia (YSZ) is the most widely used thermal barrier coating ceramic layer material in the past few decades. However, with the continuous increase in the engine turbine inlet temperature, the YSZ coating has problems such as phase change and accelerated sintering rate when facing a high temperature environment of more than 1200℃ for a long time, resulting in premature peeling and failure of the coating. Therefore, it is particularly necessary to develop a new ceramic layer material with higher heat resistance and longer service life.

[0005] Due to its ultra-high melting point (3100℃, YSZ is 2677℃), good thermal insulation performance (thermal conductivity at 1200℃ is 2.5W m -1 K -1 ), suitable thermal expansion coefficient (9.5-11.5×10 -6 K -1 , 200-1200℃), lower elastic modulus, better sintering resistance and high temperature phase stability than YSZ, BMT ceramics (Ba(Mg 1 / 3 Ta 2 / 3 )O3) has become a new candidate material for ultra-high temperature thermal barrier coating ceramic layer with good application potential.

[0006] However, the applicant found that the thermal cycling performance of the BMT coating deposited by the existing technology, that is, the most widely used APS technology, is not ideal. Even if the BMT-YSZ dual ceramic layer structure is used, its thermal cycling life is still lower than that of the YSZ coating. The main reason is that the fracture toughness of the BMT coating is low, and the layered structure deposited by APS limits the strain tolerance of the coating, causing the coating to crack easily under low thermal stress. This problem also exists in other new thermal barrier coating ceramic layer candidate materials.

[0007] In order to increase the strain tolerance of the coating and improve its thermal cycling performance, electron beam physical vapor deposition and plasma physical vapor deposition technologies have been developed successively. The ceramic coatings deposited by these two technologies have columnar or feather-like structural features, which can significantly increase the strain tolerance of the coating and extend the thermal cycling life of the coating. However, the equipment used in these two technologies is expensive, resulting in extremely high preparation costs, and is not suitable for large-scale promotion and application. Summary of the invention

[0008] In order to overcome the technical defect of insufficient thermal cycle life of thermal barrier coatings in high temperature environment in the prior art, the present invention provides a long-life ultra-high temperature thermal barrier coating and a preparation method thereof. The thermal barrier coating has a long high temperature resistance life, and the preparation method can ensure that the preparation cost is kept at a low level to meet practical application needs.

[0009] The invention provides a long-life ultra-high temperature thermal barrier coating, which is arranged on a high-temperature alloy substrate, and comprises a CoNiCrAlY metal bonding layer, a YSZ transition layer and a BMT ceramic layer which are sequentially deposited from bottom to top; the mass fractions of the components of the CoNiCrAlY metal bonding layer are: 38.5% Co, 32% Ni, 21% Cr, 8% Al and 0.5% Y; the material of the YSZ transition layer is ZrO2 powder added with 6-8wt% Y2O3; the material of the BMT ceramic layer is BMT liquid material.

[0010] Preferably, the thickness of the CoNiCrAlY metal bonding layer is 50-100 μm; the thickness of the YSZ transition layer is 150-250 μm; and the thickness of the BMT ceramic layer is 250-350 μm.

[0011] The present invention also provides a method for preparing a long-life ultra-high temperature thermal barrier coating, comprising the following steps: S1. Cleaning the surface of the high-temperature alloy substrate with acetone, and then roughening the surface by sandblasting; S2, using atmospheric plasma spraying technology APS to prepare a CoNiCrAlY metal bonding layer on the surface of the high-temperature alloy substrate treated in step S1; S3, continuing to use the atmospheric plasma spraying technology APS to prepare the YSZ transition layer on the surface of the CoNiCrAlY metal bonding layer; S4. The BMT ceramic layer is prepared on the surface of the YSZ transition layer by using suspension plasma spraying technology SPS.

[0012] Preferably, in step S2, the spraying parameters are: spraying current is 550~650A, the flow rate of the main gas Ar is 40~60L / min, the flow rate of the auxiliary gas He is 6~8L / min, the flow rate of the carrier gas Ar is 5~7L / min, the powder feeding rate is 30~50g / min, the spraying distance is 70~80mm, and the preheating temperature of the high-temperature alloy substrate is 50~150℃.

[0013] Preferably, in step S3, the spraying parameters are: spraying current is 800~900A, the flow rate of the main gas Ar is 30~50L / min, the flow rate of the auxiliary gas He is 15~25L / min, the flow rate of the carrier gas Ar is 4~6L / min, the powder feeding rate is 30~50g / min, the spraying distance is 70~80mm, and the preheating temperature of the high-temperature alloy substrate is 100~200℃.

[0014] Preferably, in step S4, the spraying parameters are: spraying current is 750~950A, the flow rate of the main gas Ar is 30~50L / min, the flow rate of the auxiliary gas He is 5~25L / min, the feeding rate of the BMT liquid is 25~35ml / min, the spraying distance is 45~55mm, and the preheating temperature of the high-temperature alloy substrate is 200~400℃.

[0015] Preferably, in step S4, the preparation steps of BMT liquid material are: S41, mechanically ball milling the BMT powder synthesized by the solid phase reaction method and anhydrous ethanol according to a solid-liquid volume ratio of 1:2-1:4, the mass ratio of grinding balls to BMT powder is 1:3-1:5, the rotation speed of the ball mill is 350-450 rpm, and the ball milling time is 2-4 hours; S42, drying the slurry obtained in step S41 at 100-120° C., and then sieving with a sieve to obtain BMT crushed powder; S43, mechanically ball-milling the BMT crushed powder obtained in step S42, the dispersant PEI and anhydrous ethanol to obtain a BMT liquid material, wherein the solid content of the liquid material is 10-30wt%, the amount of the dispersant PEI added is 1-2wt%, the ball milling speed is 300-400rpm, and the ball milling time is 2-4h.

[0016] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects: The preparation method of the thermal barrier coating proposed in the present invention is relatively simple, low in cost, and easy to achieve large-scale production; the BMT ceramic layer prepared by SPS proposed in the present invention has a columnar crystal microstructure, which can significantly increase the strain tolerance of the coating and reduce the thermal stress accumulation in the thermal cycle of the coating. The thermal barrier coating prepared by the present invention has excellent thermal cycle performance and good bonding strength and thermal insulation performance. Compared with the BMT-YSZ dual ceramic coating prepared by APS in the prior art, the thermal barrier coating prepared by the present invention has a thermal cycle life increased by more than 39 times, and more than 33 times that of the YSZ coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 Schematic cross-sectional view of the BMT-YSZ-CoNiCrAlY thermal barrier coating described in Example 1 of the present invention; Figure 2 The surface XRD spectrum of the BMT-YSZ-CoNiCrAlY thermal barrier coating prepared in Example 1 of the present invention; Figure 3 This is a cross-sectional microstructure diagram of the BMT-YSZ-CoNiCrAlY thermal barrier coating prepared in Example 1 of the present invention; Figure 4 This is a comparison diagram of the macroscopic morphology of the BMT-YSZ-CoNiCrAlY thermal barrier coating prepared in Example 1 of the present invention and after 3000 thermal cycles at 1400°C; Figure 5 This is a cross-sectional microstructure diagram of the BMT-YSZ-CoNiCrAlY thermal barrier coating prepared in Example 1 of the present invention after 3000 thermal cycles at 1400°C; Figure 6 This is a macroscopic morphology of the BMT-YSZ dual ceramic thermal barrier coating prepared in the comparative example of the present invention after 75 thermal cycles at 1400°C; Figure 7 It is a comparison chart of the thermal cycle life of the YSZ coating prepared by the prior art APS technology, the BMT-YSZ dual ceramic thermal barrier coating prepared in the comparative example, and the BMT-YSZ-CoNiCrAlY thermal barrier coating prepared in Example 1. DETAILED DESCRIPTION

[0020] In order to more clearly understand the above-mentioned objectives, features and advantages of the present invention, the scheme of the present invention will be further described below. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0021] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present invention, rather than all of the embodiments.

[0022] The following is combined with Figures 1 to 7 The specific embodiments of the present invention are described in detail.

[0023] In Example 1, a long-life ultra-high temperature thermal barrier coating is disclosed, which is deposited on a high-temperature alloy substrate. The thermal barrier coating includes a CoNiCrAlY metal bonding layer, a YSZ transition layer and a BMT ceramic layer deposited in sequence from bottom to top; the mass fractions of the components of the CoNiCrAlY metal bonding layer are: 38.5% Co, 32% Ni, 21% Cr, 8% Al and 0.5% Y; the material of the YSZ transition layer is ZrO2 powder added with 8wt% Y2O3; the material of the BMT ceramic layer is BMT liquid.

[0024] Based on the above embodiment 1, in a preferred embodiment, the thickness of the CoNiCrAlY metal bonding layer is 50-100 μm; the thickness of the YSZ transition layer is 150-250 μm; and the thickness of the BMT ceramic layer is 250-350 μm.

[0025] Based on the above embodiment 1, in a preferred embodiment, the preparation method of BMT liquid material is: S41, BaCO3, Ta2O5 and MgO were used as raw materials, and BMT powder was synthesized by solid phase reaction method by calcining at 1450℃ for 4h; BMT powder and anhydrous ethanol were mechanically ball milled at a solid-liquid volume ratio of 1:3, the mass ratio of grinding balls to BMT powder was 1:4, the ball milling speed was 400rpm, and the ball milling time was 3h; S42, drying the slurry obtained in step S41 at 110° C., and then sieving with a sieve to obtain BMT crushed powder; S43, mechanically ball-milling the BMT crushed powder obtained in step S42, the dispersant PEI and anhydrous ethanol to obtain a BMT liquid material, wherein the solid content of the liquid material is 30wt%, the amount of the dispersant PEI added is 2wt%, the ball milling speed is 350rpm, and the ball milling time is 3h.

[0026] In this embodiment 1, the specific preparation method of the BMT-YSZ-CoNiCrAlY thermal barrier coating includes the following steps: S1. Select nickel-based high-temperature alloy GH3128 as the substrate, clean the surface of the high-temperature alloy substrate with acetone to remove oil and dust, and then roughen the surface by sandblasting; the sandblasting uses -24 mesh white corundum sand, and the sandblasting is performed under a pressure of 0.5MPa; and then use dry compressed air to blow away the sand and dust attached to the roughened surface; S2. A CoNiCrAlY metal bonding layer is prepared on the surface of the high-temperature alloy substrate treated in step S1 by using atmospheric plasma spraying technology APS; the spraying parameters are: spraying current is 580A, the flow rate of the main gas Ar is 47L / min, the flow rate of the auxiliary gas He is 7L / min, the flow rate of the carrier gas Ar is 6L / min, the powder feeding rate is 35g / min, the spraying distance is 75mm, the preheating temperature of the high-temperature alloy substrate is 100°C, and the thickness of the sprayed CoNiCrAlY metal bonding layer is about 80μm; S3. A YSZ transition layer was prepared on the surface of the CoNiCrAlY metal bonding layer by atmospheric plasma spraying technology APS; the spraying parameters were: spraying current was 850A, the flow rate of the main gas Ar was 38L / min, the flow rate of the auxiliary gas He was 21L / min, the flow rate of the carrier gas Ar was 5L / min, the powder feeding rate was 40g / min, the spraying distance was 75mm, and the preheating temperature of the high-temperature alloy substrate was 150°C; the thickness of the sprayed YSZ transition layer was about 200μm; S4. Prepare a BMT ceramic layer on the surface of the YSZ transition layer using suspension plasma spraying technology SPS. The spraying parameters are: spraying current is 950A, the flow rate of the main gas Ar is 33L / min, the flow rate of the auxiliary gas He is 24L / min, the feeding rate of the BMT liquid is 30ml / min, the spraying distance is 50mm, and the preheating temperature of the high-temperature alloy substrate is 280℃; the thickness of the BMT ceramic layer is about 300μm. After steps S1-S4 are completed, a BMT-YSZ-CoNiCrAlY thermal barrier coating can be obtained.

[0027] The phase structure, cross-sectional organization, bonding strength, thermal insulation performance and thermal cycle performance of the BMT-YSZ-CoNiCrAlY thermal barrier coating prepared in this example were tested.

[0028] The phase structure of BMT-YSZ-CoNiCrAlY thermal barrier coating was tested by X-ray diffractometer. Figure 2 The surface XRD spectrum of the prepared thermal barrier coating is compared with the BMT XRD standard card PDF#87-1733, and it is found that the diffraction peaks of the prepared thermal barrier coating are consistent with the standard diffraction peaks.

[0029] The cross-sectional structure of the BMT-YSZ-CoNiCrAlY thermal barrier coating was observed by scanning electron microscopy. Figure 3 This is the cross-sectional microstructure of the prepared thermal barrier coating. It can be seen that the CoNiCrAlY metal bonding layer and YSZ transition layer prepared by APS present a typical layered microstructure, while the BMT ceramic layer prepared by SPS presents a columnar crystal structure, which meets the structural characteristics of high strain tolerance.

[0030] The bonding strength of the BMT-YSZ-CoNiCrAlY thermal barrier coating was tested by the adhesive coupling tensile method according to the ASTM C633-2013 test standard. After testing, the bonding strength of the BMT-YSZ-CoNiCrAlY thermal barrier coating prepared in this embodiment was 38.9 MPa.

[0031] The thermal insulation and thermal cycle performance of the BMT-YSZ-CoNiCrAlY thermal barrier coating were tested using a gas burner test device. Specifically, the surface of the prepared thermal barrier coating was quickly heated using a high-temperature flame generated by the combustion of propane, oxygen and compressed air. The temperature reached 1400°C and was kept warm for 5 minutes. The flame was then removed and the sample was forced to cool for 100 seconds using compressed air. After cooling, the sample was heated again, and the cycle was repeated until the failure area of ​​the coating exceeded 20%. The number of cycles at this time is the thermal cycle life of the thermal barrier coating. The thermal insulation performance of the thermal barrier coating is determined by the temperature difference between the surface and back of the coating during the insulation stage.

[0032] The thermal barrier coating has been tested to have a heat insulation capacity of 520°C and can maintain a relatively intact surface morphology after 3,000 thermal cycles. Figure 4 This is a comparison of the macroscopic morphologies of a thermal barrier coating prepared according to an embodiment of the present invention and after 3000 thermal cycles at 1400°C. Figure 5 This is a cross-sectional microstructure diagram of a thermal barrier coating prepared according to an embodiment of the present invention after 3000 thermal cycles at 1400°C.

[0033] In comparative example 1, nickel-based high-temperature alloy GH3128 is selected as the substrate, and the substrate pretreatment process is the same as step S1 of the specific preparation method of the BMT-YSZ-CoNiCrAlY thermal barrier coating in Example 1; then APS is used to sequentially prepare the CoNiCrAlY metal bonding layer and the YSZ transition layer on the treated GH3128 substrate, and its spraying parameters are the same as steps S2 and S3 in Example 1; APS is used to continue to prepare the BMT ceramic layer on the surface of the YSZ coating. This layer of material is BaCO3, Ta2O5 and MgO as raw materials, and the BMT powder synthesized by solid phase reaction method is obtained by spray granulation. The spraying parameters of the BMT layer are: spraying current is 750A, the flow rate of the main gas Ar is 38L / min, the flow rate of the carrier gas Ar is 5L / min, the feeding rate of the BMT powder is 35g / min, the spraying distance is 60mm, and the preheating temperature of the high-temperature metal substrate is 120°C, and finally a BMT-YSZ dual ceramic thermal barrier coating is obtained.

[0034] The bonding strength, thermal insulation performance and thermal cycle performance of the BMT-YSZ dual ceramic thermal barrier coating prepared in this comparative example were tested.

[0035] The bonding strength of the BMT-YSZ dual ceramic thermal barrier coating was tested using the adhesive coupling tensile method according to the ASTM C633-2013 test standard. The test showed that the bonding strength of the BMT-YSZ dual ceramic thermal barrier coating was 18.9MPa.

[0036] The thermal insulation and thermal cycle performance tests of the BMT-YSZ dual ceramic thermal barrier coating were carried out using a gas burner test device. Specifically, the high-temperature flame generated by the combustion of propane, oxygen and compressed air was used to quickly heat the surface of the obtained BMT-YSZ dual ceramic thermal barrier coating to 1400°C and keep it warm for 5 minutes. The flame was then removed and the sample was forced to cool for 100 seconds using compressed air. After cooling, the sample was heated again, and the cycle was repeated until the failure area of ​​the BMT-YSZ dual ceramic thermal barrier coating exceeded 20%. The number of cycles at this time is the thermal cycle life of the BMT-YSZ dual ceramic thermal barrier coating. The thermal insulation performance of the BMT-YSZ dual ceramic thermal barrier coating is determined by the temperature difference between the surface and back of the BMT-YSZ dual ceramic thermal barrier coating during the insulation stage.

[0037] After testing, the thermal insulation capacity of the BMT-YSZ dual ceramic thermal barrier coating is 450°C. The BMT-YSZ dual ceramic thermal barrier coating reaches the failure standard after 75 thermal cycles at 1400°C. Figure 6 This is the macroscopic morphology of the BMT-YSZ dual ceramic thermal barrier coating after 75 thermal cycles at 1400℃. Figure 7It is a comparison chart of thermal cycle life of the YSZ coating prepared by the existing APS technology, the comparative example BMT-YSZ dual ceramic coating and the thermal barrier coating prepared in Example 1 of the present invention.

[0038] The above results prove that compared with the BMT-YSZ dual ceramic coating prepared by APS in the prior art, the long-life ultra-high temperature thermal barrier coating provided by the present invention not only has a higher thermal cycle life, but also has good bonding strength and thermal insulation performance. In addition, the coating preparation process provided by the present invention is simple to operate, low in cost, and easy to achieve large-scale production.

[0039] The above is only a specific implementation of the present invention, which enables those skilled in the art to understand or implement the present invention. Although detailed descriptions are given with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments, and they should all be covered by the protection scope of the claims.

Claims

1. A long-life ultra-high temperature thermal barrier coating, the thermal barrier coating is arranged on a high temperature alloy substrate, characterized in that: It includes a CoNiCrAlY metal bonding layer, a YSZ transition layer and a BMT ceramic layer deposited in sequence from bottom to top; the mass fractions of the components of the CoNiCrAlY metal bonding layer are: 38.5% Co, 32% Ni, 21% Cr, 8% Al and 0.5% Y; the material of the YSZ transition layer is ZrO2 powder added with 6~8wt% Y2O3; the material of the BMT ceramic layer is BMT liquid.

2. The long-life ultra-high temperature thermal barrier coating according to claim 1, characterized in that: The thickness of the CoNiCrAlY metal bonding layer is 50-100 μm; the thickness of the YSZ transition layer is 150-250 μm; and the thickness of the BMT ceramic layer is 250-350 μm.

3. A method for preparing a long-life ultra-high temperature thermal barrier coating, characterized in that: The following steps are involved: S1. Cleaning the surface of the high-temperature alloy substrate with acetone, and then roughening the surface by sandblasting; S2, using atmospheric plasma spraying technology APS to prepare a CoNiCrAlY metal bonding layer on the surface of the high-temperature alloy substrate treated in step S1; S3, continuing to use the atmospheric plasma spraying technology APS to prepare the YSZ transition layer on the surface of the CoNiCrAlY metal bonding layer; S4. The BMT ceramic layer is prepared on the surface of the YSZ transition layer by using suspension plasma spraying technology SPS.

4. The method for preparing a long-life ultrahigh temperature thermal barrier coating according to claim 3, characterized in that: In step S2, the spraying parameters are: spraying current is 550~650A, the flow rate of the main gas Ar is 40~60L / min, the flow rate of the auxiliary gas He is 6~8L / min, the flow rate of the carrier gas Ar is 5~7L / min, the powder feeding rate is 30~50g / min, the spraying distance is 70~80mm, and the preheating temperature of the high-temperature alloy substrate is 50~150℃.

5. The method for preparing a long-life ultra-high temperature thermal barrier coating according to claim 3, characterized in that: In step S3, the spraying parameters are: spraying current is 800~900A, the flow rate of the main gas Ar is 30~50L / min, the flow rate of the auxiliary gas He is 15~25L / min, the flow rate of the carrier gas Ar is 4~6L / min, the powder feeding rate is 30~50g / min, the spraying distance is 70~80mm, and the preheating temperature of the high-temperature alloy substrate is 100~200℃.

6. The method for preparing a long-life ultrahigh temperature thermal barrier coating according to claim 3, characterized in that: In step S4, the spraying parameters are: spraying current is 750~950A, the flow rate of the main gas Ar is 30~50L / min, the flow rate of the auxiliary gas He is 5~25L / min, the feeding rate of the BMT liquid is 25~35ml / min, the spraying distance is 45~55mm, and the preheating temperature of the high-temperature alloy substrate is 200~400℃.

7. A method for preparing a long-life ultrahigh temperature thermal barrier coating according to any one of claims 3 to 6, characterized in that: In step S4, the preparation steps of BMT liquid are as follows: S41, mechanically ball milling the BMT powder synthesized by the solid phase reaction method and anhydrous ethanol according to a solid-liquid volume ratio of 1:2-1:4, the mass ratio of grinding balls to BMT powder is 1:3-1:5, the rotation speed of the ball mill is 350-450 rpm, and the ball milling time is 2-4 hours; S42, drying the slurry obtained in step S41 at 100-120° C., and then sieving with a sieve to obtain BMT crushed powder; S43, mechanically ball-milling the BMT crushed powder obtained in step S42, the dispersant PEI and anhydrous ethanol to obtain a BMT liquid material, wherein the solid content of the liquid material is 10-30wt%, the amount of the dispersant PEI added is 1-2wt%, the ball milling speed is 300-400rpm, and the ball milling time is 2-4h.

8. The method for preparing a long-life ultrahigh temperature thermal barrier coating according to claim 7, characterized in that: In step S41, BaCO3, Ta2O5 and MgO are used as raw materials and calcined at 1450°C for 4 hours to synthesize BMT powder.

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