A thermal barrier coating for a superalloy surface and a method of manufacture

Abstract

The application discloses a thermal barrier coating for a high-temperature alloy surface and a preparation method thereof. The thermal barrier coating comprises, from the high-temperature alloy surface to the outside, a bonding layer, a first ceramic thermal barrier layer, a second ceramic thermal barrier layer and a sacrificial coating layer. The roughness Ra of the interface between the bonding layer and the first ceramic thermal barrier layer is 11-13 mu m, and the roughness Ra of the interface between the first ceramic thermal barrier layer and the second ceramic thermal barrier layer is 12-17 mu m. The first ceramic thermal barrier layer comprises ZrO2 and Y2O3, and the mass percentage of Y2O3 is 6-8%. The second ceramic thermal barrier layer comprises ZrO2, Y2O3, Yb2O3 and Gd2O3, and the mass percentage of Y2O3 is 9-10%, the mass percentage of Yb2O3 is 5-6%, and the mass percentage of Gd2O3 is 4.7-5.7%. The bonding layer of the high-temperature alloy surface is first sprayed by using a spraying device, the bonding layer is sandblasted to improve the surface roughness, the first ceramic thermal barrier layer is sprayed, the spraying angle is changed in at least the last spraying, the surface roughness of the first ceramic thermal barrier layer is improved, and finally the second ceramic thermal barrier layer and the sacrificial coating layer are sprayed in sequence.

Description

Technical Field

[0001] This invention relates to the field of thermal barrier coating preparation and repair, and specifically to a thermal barrier coating for high-temperature alloy surfaces and its preparation method. Background Technology

[0002] Heavy-duty gas turbines are core power equipment using high-temperature gas as the working fluid. They represent a national strategic high technology and are a benchmark for the level of major equipment manufacturing, impacting national energy security, defense security, and industrial competitiveness. Turbine blades are key hot-end components that determine the output power of a gas turbine and are crucial to the overall performance of the turbine. The combustion chamber and turbine components of heavy-duty gas turbines are larger than those of aero engines, and the thermal barrier coating area is much larger than that of similar components in aero engines. As gas turbine efficiency increases, the service temperature of turbine blades also increases. During operation, they are subjected to high-temperature and high-pressure gas impacts exceeding 1400°C, far exceeding the temperature limit of the high-temperature alloy materials used in the base material (approximately 1000°C). Therefore, turbine blades must be cooled, employing a hollow cooling structure and applying a thermal barrier coating to the gas erosion surface. The combustion chamber must also use a high-temperature alloy as its outer shell, with a thick thermal barrier coating inside to ensure safe and reliable operation of the transition section at high temperatures.

[0003] As the power rating and efficiency of gas turbines increase, the gas inlet temperature also increases accordingly. Generally, the gas temperature of an F-class gas turbine reaches 1450℃, while that of a G / H-class gas turbine is increased by 100℃, and that of a J-class gas turbine is increased by another 100℃. The improved endurance strength of new high-temperature alloys obviously cannot reach the 100℃ level. Generally, the highest-grade high-temperature alloys that meet the design conditions have difficulty exceeding 1000℃ in long-term operation. At present, the highest temperature of the turbine blade alloys of F-class gas turbines can reach about 900℃. Obviously, the applicability of the thermal barrier coatings originally used in F-class gas turbines for G / H-class gas turbines is already close to the limit. J-class gas turbines obviously need new high thermal resistance thermal barrier coatings to provide the heat insulation and temperature resistance provided by thermal barrier coatings.

[0004] Traditional thermal barrier coatings consist of a metal bonding layer and a ceramic insulation layer. The metal bonding layer is generally MCrAlY (M is Ni, Co, or a mixture of both). The ceramic insulation layer of F-class gas turbines uses 6-8% wt yttrium oxide-stabilized zirconium oxide. When the insulation requirement is high, it is usually achieved by increasing the thickness of the insulation layer and increasing its porosity. YSZ undergoes a phase transition at 1170 degrees Celsius, which leads to a 4% volume change. Under normal circumstances, this characteristic increases the risk of detachment, and the application of YSZ is generally limited to the range of 1200-1250 degrees Celsius. New materials with higher temperature resistance and lower thermal conductivity mainly include defective pyrochlore materials and their doped types such as Gd2Zr2O7, La2Zr2O7, Gd2-xRExZr2O7 and La2-xRExZr2O7; composite doped t' phase or t phase YSZ, namely GdO-YbO-YO-ZrO, TaO-YO-ZrO, etc., all belong to this type, as well as rare earth Ta salts, alumina magnesium salts, etc.

[0005] Most novel materials with low thermal conductivity cannot currently be used alone because their physical properties differ significantly from those of the adhesive layer, making them prone to detachment when used alone. It is necessary to first spray anodized and stabilized zirconia as a transition layer after applying the adhesive layer, and then continue spraying the low thermal conductivity material on top of the zirconia. The lifespan of this two-layer coating system is not ideal. In the tests conducted, peeling was commonly observed between the ceramic layers and between the adhesive layer and the zirconia. Furthermore, during operation, the airflow contains thermally corrosive substances such as SO2, K salts, and sodium salts, as well as low-melting-point CMAS dust. For units using abrasive coatings, the airflow may also contain metal and ceramic particles, all of which can adversely affect the coating's performance.

[0006] Patent document CN103874580B discloses a thermal barrier coating system and method thereof, comprising an inner ceramic layer and an outer ceramic layer. The inner ceramic layer is substantially composed of zirconium oxide stabilized by about 6-9% yttrium oxide and optionally contains more than 0.5-10% hafnium oxide. The outer ceramic layer covers and contacts the inner ceramic layer to define the outermost surface of the coating system. The outer ceramic layer is substantially composed of zirconium oxide stabilized by about 25-75% by weight yttrium oxide, has a thickness less than that of the inner ceramic layer, and also contains more than 0.5-10% by weight hafnium oxide and optionally 1-10% tantalum oxide. The problem remains unresolved: the difference in physical properties between the ceramic layer and the adhesive layer makes it prone to detachment, reducing contaminant adhesion.

[0007] Patent document CN109468639B discloses an ultra-limit zirconium alloy and its preparation method, comprising a zirconium alloy substrate, on which a bonding layer, a noble metal layer, a ceramic A layer, a ceramic B layer, a sealing coating, a reflective layer, a reflective layer, and an electrical insulating layer are sequentially deposited. The preparation method of the ultra-limit zirconium alloy involves sequentially depositing the bonding layer, noble metal layer, ceramic A layer, ceramic B layer, sealing coating, reflective layer, reflective layer, and electrical insulating layer onto the surface of the zirconium alloy substrate. However, this method fails to address the issue of the ceramic layer and bonding layer easily detaching due to differences in their physical properties, thus hindering the reduction of contaminant adhesion. Summary of the Invention

[0008] Based on the above-mentioned technical problems, this invention proposes a thermal barrier coating for high-temperature alloy surfaces and a preparation method thereof, which solves the problem that the ceramic layer and the adhesive layer are prone to peeling off due to differences in physical properties in the prior art, and reduces the adhesion of contaminants.

[0009] To achieve the above objectives, the present invention proposes a thermal barrier coating for high-temperature alloy surfaces.

[0010] A thermal barrier coating for a high-temperature alloy surface comprises, from near to far, an adhesive layer, a first ceramic insulation layer, a second ceramic insulation layer, and a sacrificial coating, starting from the surface of the high-temperature alloy. The roughness Ra of the interface between the adhesive layer and the first ceramic insulation layer is 11 μm-13 μm, and the roughness Ra of the interface between the first ceramic insulation layer and the second ceramic insulation layer is 12 μm-17 μm. The first ceramic insulation layer comprises ZrO2 and Y2O3, wherein the mass percentage of Y2O3 is 6%-8%. The second ceramic insulation layer comprises ZrO2, Y2O3, Yb2O3, and Gd2O3, wherein the mass percentage of Y2O3 is 9%-10%, the mass percentage of Yb2O3 is 5%-6%, and the mass percentage of Gd2O3 is 4.7%-5.7%.

[0011] Furthermore, the material composition of the first adhesive layer includes Co, Ni, Cr, Al and Y, and by mass percentage contains 31%-33% Ni, 20%-22% Cr, 7%-9% Al and 0.5%-1% Y, with the balance being Co and unavoidable impurities. The particle size of the raw material powder of the first adhesive layer is 22μm-45μm, and the thickness of the first adhesive layer is 240μm-300μm.

[0012] The first adhesive layer comprises Co, Ni, Cr, Al and Y, and by mass percentage contains 30%-33% Ni, 20%-22% Cr, 6%-9% Al and 0.5%-1% Y, with the balance being Co and unavoidable impurities. The particle size of the raw material powder for the first adhesive layer is 45μm-90μm, and the thickness of the second adhesive layer is 55μm-65μm.

[0013] Furthermore, the thickness of the first ceramic heat insulation layer is 225μm-275μm;

[0014] The thickness of the second ceramic heat insulation layer is 230μm-270μm.

[0015] Furthermore, the combined thickness of the first ceramic insulation layer and the second ceramic insulation layer is 470μm-520μm.

[0016] Furthermore, the porosity deviation between the first ceramic insulation layer and the second ceramic insulation layer is 1%-4%.

[0017] Furthermore, the powder used for spraying the sacrificial coating is La. 0.5 Yb 0.5 Zr2O7 powder.

[0018] Furthermore, the diameter of the sprayed powder is 15μm-20μm.

[0019] Furthermore, the thickness of the sacrificial coating is 15μm-30μm.

[0020] Furthermore, the surface roughness Ra of the sacrificial coating is 1.19 μm-1.2 μm.

[0021] To achieve the above objectives, the present invention also proposes a method for preparing a thermal barrier coating for high-temperature alloy surfaces.

[0022] A method for preparing a thermal barrier coating for high-temperature alloy surfaces, characterized by comprising:

[0023] S1: Using a spraying device, the raw material powder is sprayed onto the surface of the high-temperature alloy to a preset thickness to complete the spraying of the adhesive layer. The adhesive layer is then sandblasted to improve its surface roughness.

[0024] S2: Use a spraying device to spray the first ceramic heat insulation layer at the interface of the adhesive layer. In at least the last spraying, change the spraying angle to complete the spraying of the first ceramic heat insulation layer. Sandblast the first ceramic heat insulation layer to improve the surface roughness. Use a plasma flame to preheat the surface of the first ceramic heat insulation layer. After reaching the preheating temperature, spray the second ceramic heat insulation layer according to a predetermined path.

[0025] S3: Apply the sacrificial coating.

[0026] Furthermore, step S1 also includes:

[0027] First, the first adhesive layer is applied using supersonic flame spraying to achieve the preset thickness. Then, the second adhesive layer is applied using atmospheric plasma spraying.

[0028] Furthermore, step S1 also includes:

[0029] After the adhesive layer is applied, an aging heat treatment is performed.

[0030] Further, step S1 includes:

[0031] After the aging heat treatment is completed, the areas that need to be masked are masked, the tooling fixtures are installed and the spraying program is adjusted, and the dry ice sandblasting method with particles of 3mm-5mm is adopted for sandblasting.

[0032] Furthermore, step S2 also includes:

[0033] In the last one or two coats of the first ceramic insulation layer, the spray gun angle is changed from 90 degrees perpendicular to the surface to 60-80 degrees for spraying.

[0034] Furthermore, step S2 also includes:

[0035] After the first ceramic heat insulation layer is sprayed, different sandblasting pipes are used to sandblast the surface of the first ceramic heat insulation layer together with 20-60 mesh fused zirconium crushed sand and dry ice with a particle diameter of 3mm-5mm as sandblasting media.

[0036] Furthermore, step S2 also includes:

[0037] The temperature of the first ceramic insulation layer is preheated to 200℃-500℃.

[0038] Furthermore, step S3 also includes:

[0039] When spraying the sacrificial coating, the spraying distance is 80mm-120mm and the powder feeding speed is 48g / min-52g / min.

[0040] Furthermore, step S3 also includes:

[0041] After the sacrificial coating is applied, the surface of the sacrificial coating is polished.

[0042] Based on the above technical solution, the present invention has at least the following beneficial effects:

[0043] 1. This invention proposes a thermal barrier coating for high-temperature alloy surfaces. Through a series of coating preparation steps, the mechanical bonding force between the interfaces in the thermal barrier coating is significantly improved. Precise control of the roughness between the bonding layer and the ceramic insulation layer, along with surface treatment achieved through a special sandblasting technique, enhances the coating's heat resistance. By optimizing spraying parameters and post-treatment steps, this invention significantly reduces the risk of interface contamination during thermal cycling. In simulation tests, coating samples using this invention exhibit superior durability, with their isothermal thermal cycle life increased from the conventional 400 cycles to over 1000 cycles.

[0044] 2. This invention introduces La, which has self-limiting reaction properties. 0.5 Yb 0.5 Zr2O7, acting as a sacrificial coating, reduces coating adhesion and confines contaminants within the sacrificial layer, preventing inward diffusion. Furthermore, the thermal barrier coating structure of this invention exhibits higher stability and durability when facing corrosive substances commonly encountered in gas turbine operation. This sacrificial coating effectively limits the penetration of corrosive substances, protecting the underlying thermal barrier coating from damage and thus extending the service life of the entire coating system.

[0045] 3. The thermal barrier coating structure design proposed in this invention achieves both thermal insulation and thermal corrosion resistance by using low thermal conductivity materials and optimized coating pore structure. The coating structure design of this invention enables the coating to maintain stable performance in the harsh environment of gas turbines, while reducing maintenance costs and frequency.

[0046] 4. The thermal barrier coating proposed in this invention simplifies the production process by employing mainstream coating preparation equipment and optimized spraying parameters, making the coating preparation process more efficient and economical. By precisely controlling the spraying conditions and post-treatment steps, this invention reduces potential defects in the coating preparation process, improving the consistency and reliability of the coating. The preparation method in this invention not only improves production efficiency but also reduces dependence on high-end equipment and complex processes, making the coating technology of this invention easier to widely apply in industrial production. Attached Figure Description

[0047] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0048] Figure 1 A cross-sectional view of the thermal barrier coating composition structure of one embodiment is shown;

[0049] Figure 2 A schematic diagram of dry ice blasting is shown of the adhesive layer interface of a thermal barrier coating according to one embodiment.

[0050] Figure 3 A schematic diagram of the bonding layer interface of a thermal barrier coating in one embodiment is shown, which is simultaneously subjected to dry ice blasting and particle blasting. Detailed Implementation

[0051] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0052] The present invention will be further described in detail below with reference to specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed by the present invention. The term "comprising" indicates the presence of a feature, but does not exclude the presence or addition of one or more other features. The terms "lateral," "upper," "lower," "front," "rear," "left," "right," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the purpose of description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0053] In this description, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0054] Example

[0055] This invention proposes a thermal barrier coating for high-temperature alloy surfaces, such as... Figure 1 The structure includes an adhesive layer, a first ceramic insulation layer, a second ceramic insulation layer, and a sacrificial coating. The roughness Ra of the interface between the adhesive layer and the first ceramic insulation layer is 11 μm-13 μm, and the roughness Ra of the interface between the first ceramic insulation layer and the second ceramic insulation layer is 12 μm-17 μm. The material composition of the first ceramic insulation layer includes ZrO2 and Y2O3, wherein the mass percentage of Y2O3 is 6%-8%. The material composition of the second ceramic insulation layer includes ZrO2, Y2O3, Yb2O3, and Gd2O3, wherein the mass percentage of Y2O3 is 9%-10%, the mass percentage of Yb2O3 is 5%-6%, and the mass percentage of Gd2O3 is 4.7%-5.7%.

[0056] Example 1

[0057] The first adhesive layer uses powder with a mass composition of Co, 31% Ni, 20% Cr, 7% Al and 0.5% Y and a particle diameter of 22 μm. The second adhesive layer uses powder with a mass composition of Co, 31% Ni, 20% Cr, 7% Al and 0.5% Y and a particle diameter of 45 μm. The first ceramic insulation layer uses powder composed of ZrO2 and Y2O3, with Y2O3 accounting for 6% by mass and the remainder being ZrO2. The second ceramic insulation layer uses powder composed of ZrO2, Y2O3, Yb2O3, and Gd2O3, with Y2O3 accounting for 9% by mass, Yb2O3 accounting for 5% by mass, and Gd2O3 accounting for 4.7% by mass. The thickness of the first adhesive layer is 240 μm, the thickness of the second adhesive layer is 55 μm, the thickness of the first ceramic insulation layer sprayed is 225 μm, the thickness of the second ceramic insulation layer sprayed is 230 μm, and the thickness of the sacrificial coating is 15 μm. The thermal barrier coating prepared in this embodiment has a cycle life of more than 800 cycles in 1 hour.

[0058] In a method for preparing a thermal barrier coating for a high-temperature alloy surface according to this embodiment, the method includes:

[0059] The first adhesive layer, 240 μm thick, is applied using supersonic flame spraying, achieving a surface roughness Ra of 5 μm. After reaching the preset thickness, a second adhesive layer is applied, this time 55 μm thick, using atmospheric plasma spraying to achieve a surface roughness Ra of 11 μm. Following the adhesive layer application, aging heat treatment is performed, and areas requiring masking are masked. The necessary fixtures are then installed and the spraying program is adjusted. Figure 2 The process involves dry ice blasting with 3mm particles to reduce the original TGO particle size to less than 0.5μm. The first ceramic insulation layer is then applied. In the final coat of the first ceramic insulation layer, the spray gun angle is changed from 90 degrees perpendicular to the surface to 60 degrees, causing the particle stream to impact the surface at an angle, creating more wave-like patterns. After the first ceramic insulation layer is applied, as shown... Figure 3The process involved using different blasting pipes to blast the surface of the first ceramic insulation layer with 20-mesh fused zirconium sand and dry ice with a particle diameter of 3 mm as blasting media. The surface of the first ceramic insulation layer was then preheated using a plasma flame and measured with an infrared thermometer. The preheating temperature reached 200°C before spraying the second ceramic insulation layer. The resulting first ceramic insulation layer comprised 12% and 14% of the first ceramic insulation layer. Finally, the sacrificial coating was applied at a spraying distance of 100 mm and a powder feeding rate of 50 g / min. After completing the sacrificial coating, the surface roughness Ra was less than 3.2 μm. The surface of the sacrificial coating was then sandblasted and polished to achieve a surface roughness Ra of 1.2 μm.

[0060] Example 2

[0061] Preferably, a powder with a mass composition of Co, 32% Ni, 21% Cr, 8% Al and 0.7% Y and a particle diameter of 30 μm is used as the raw material powder for the first adhesive layer, and a powder with a mass composition of Co, 32% Ni, 21% Cr, 8% Al and 0.7% Y and a particle diameter of 60 μm is used as the raw material powder for the second adhesive layer. The first ceramic insulation layer uses powder with a material composition of ZrO2 and Y2O3, wherein the mass percentage of Y2O3 is 7%, as the raw material. The second ceramic insulation layer uses powder with a material composition of ZrO2, Y2O3, Yb2O3 and Gd2O3, wherein the mass percentage of Y2O3 is 9.5%, the mass percentage of Yb2O3 is 5.5%, and the mass percentage of Gd2O3 is 5.2%. The thickness of the first adhesive layer is 270 μm, the thickness of the second adhesive layer is 60 μm, the ratio of the thickness of the first ceramic insulation layer to the thickness of the second ceramic insulation layer is 1:1, the sprayed thickness of the first ceramic insulation layer is 250 μm, the sprayed thickness of the second ceramic insulation layer is 250 μm, and the thickness of the sacrificial coating is 20 μm. The thermal barrier coating prepared in this embodiment has a cycle life of more than 1000 cycles in 1 hour.

[0062] In a method for preparing a thermal barrier coating for a high-temperature alloy surface according to this embodiment, the method includes:

[0063] Preferably, the first adhesive layer is sprayed to a thickness of 270 μm using supersonic flame spraying, achieving a surface roughness Ra of 6 μm. After reaching the preset thickness, the second adhesive layer is sprayed to a thickness of 60 μm using atmospheric plasma spraying, achieving a surface roughness Ra of 13 μm. After the adhesive layer is sprayed, aging heat treatment is performed, and areas requiring masking are masked. The tooling fixtures are installed, and the spraying program is adjusted. The first ceramic insulation layer is then sprayed. In the last two passes of the first ceramic insulation layer spraying, the spray gun angle is changed from 90 degrees perpendicular to the surface to 70 degrees, causing the particle stream to impact the sprayed surface at an angle, creating more wave-like surfaces. After the first ceramic insulation layer is sprayed, as... Figure 3 The method described above uses different sandblasting pipes to sandblast the surface of the first ceramic insulation layer with 40-mesh fused zirconium sand and dry ice with a particle diameter of 4 mm as sandblasting media. The surface of the first ceramic insulation layer is preheated with a plasma flame and the temperature is measured with an infrared thermometer. The preheating temperature reaches 300°C. The second ceramic insulation layer is then sprayed, resulting in a first ceramic insulation layer with a thickness of 13% and a first ceramic insulation layer with a thickness of 14%. Finally, the sacrificial coating is sprayed. Other methods and steps are the same as in Example 1 and will not be repeated here.

[0064] Example 3

[0065] The first adhesive layer uses powder with a mass composition of Co, 33% Ni, 22% Cr, 9% Al and 1% Y and a particle diameter of 45 μm as the raw material powder, and the second adhesive layer uses powder with a mass composition of Co, 33% Ni, 22% Cr, 9% Al and 1% Y and a particle diameter of 90 μm as the raw material powder. The first ceramic insulation layer uses powder with a composition of ZrO2 and Y2O3, wherein Y2O3 accounts for 8% of the total mass, as the raw material. The second ceramic insulation layer uses powder with a composition of ZrO2, Y2O3, Yb2O3, and Gd2O3, wherein Y2O3 accounts for 10% of the total mass, Yb2O3 accounts for 6% of the total mass, and Gd2O3 accounts for 5.7% of the total mass. The thickness of the first adhesive layer is 300 μm, the thickness of the second adhesive layer is 65 μm, the thickness of the first ceramic insulation layer sprayed is 275 μm, the thickness of the second ceramic insulation layer sprayed is 270 μm, and the thickness of the sacrificial coating is 30 μm. The thermal barrier coating prepared in this embodiment has a cycle life of more than 900 cycles in 1 hour.

[0066] In a method for preparing a thermal barrier coating for a high-temperature alloy surface according to this embodiment, the method includes:

[0067] The first adhesive layer, 300 μm thick, is applied using supersonic flame spraying, achieving a surface roughness Ra of 5 μm. After reaching the preset thickness, a second adhesive layer is applied using atmospheric plasma spraying, achieving a surface roughness Ra of 12 μm and a thickness of 65 μm. Following the adhesive layer application, an aging heat treatment is performed, and areas requiring masking are masked. The tooling fixtures are installed, and the spraying program is adjusted. The first ceramic insulation layer is then sprayed. During the final two passes of the first ceramic insulation layer spraying, the spray gun angle is changed from 90 degrees perpendicular to the surface to 80 degrees, causing the particle stream to impact the sprayed surface at an angle, creating more wave-like surfaces. After the first ceramic insulation layer is applied, as shown... Figure 3 The method described above uses different blasting pipes to blast the surface of the first ceramic insulation layer with 60-mesh fused zirconium sand and dry ice with a particle diameter of 5 mm as blasting media. The surface of the first ceramic insulation layer is preheated with a plasma flame and the temperature is measured with an infrared thermometer. The preheating temperature reaches 500°C. The second ceramic insulation layer is then sprayed, resulting in a first ceramic insulation layer that is 12% and a second ceramic insulation layer that is 15% of the first ceramic insulation layer. Finally, the sacrificial coating is sprayed. Other methods and steps are the same as in Example 1 and will not be repeated here.

[0068] In summary, as can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0069] 1. This invention proposes a thermal barrier coating for high-temperature alloy surfaces. Through a series of coating preparation steps, the mechanical bonding force between the interfaces in the thermal barrier coating is significantly improved. Precise control of the roughness between the bonding layer and the ceramic insulation layer, along with surface treatment achieved through a special sandblasting technique, enhances the coating's heat resistance. By optimizing spraying parameters and post-treatment steps, this invention significantly reduces the risk of interface contamination during thermal cycling. In simulation tests, coating samples using this invention exhibit superior durability, with their isothermal thermal cycle life increased from the conventional 400 cycles to over 1000 cycles.

[0070] 2. This invention introduces La, which has self-limiting reaction properties. 0.5 Yb 0.5 Zr2O7 powder, used as a sacrificial coating, reduces coating adhesion and confines contaminants within the sacrificial layer, preventing inward diffusion. Furthermore, the thermal barrier coating structure of this invention exhibits higher stability and durability when facing corrosive substances commonly encountered in gas turbine operation. This sacrificial coating effectively limits the penetration of corrosive substances, protecting the underlying thermal barrier coating from damage, thereby extending the service life of the entire coating system.

[0071] 3. The thermal barrier coating structure design proposed in this invention achieves both thermal insulation and thermal corrosion resistance by using low thermal conductivity materials and optimized coating pore structure. The coating structure design of this invention enables the coating to maintain stable performance in the harsh environment of gas turbines, while reducing maintenance costs and frequency.

[0072] 4. The thermal barrier coating proposed in this invention simplifies the production process by employing mainstream coating preparation equipment and optimized spraying parameters, making the coating preparation process more efficient and economical. By precisely controlling the spraying conditions and post-treatment steps, this invention reduces potential defects in the coating preparation process, improving the consistency and reliability of the coating. The preparation method in this invention not only improves production efficiency but also reduces dependence on high-end equipment and complex processes, making the coating technology of this invention easier to widely apply in industrial production.

[0073] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0074] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0075] It should be noted that, in the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

Claims

1. A thermal barrier coating for high-temperature alloy surfaces, characterized in that, Starting from the surface of the high-temperature alloy and extending outwards, the material comprises an adhesive layer, a first ceramic insulation layer, a second ceramic insulation layer, and a sacrificial coating. The roughness Ra of the interface between the adhesive layer and the first ceramic insulation layer is 11 μm-13 μm, and the roughness Ra of the interface between the first ceramic insulation layer and the second ceramic insulation layer is 12 μm-17 μm. The porosity of the first ceramic insulation layer and the second ceramic insulation layer is 12%-15%. The material composition of the first ceramic insulation layer includes ZrO2 and Y2O3, wherein the mass percentage of Y2O3 is 6%-8%. The material composition of the second ceramic insulation layer includes ZrO2, Y2O3, Yb2O3, and Gd2O3, wherein the mass percentage of Y2O3 is 9%-10%, the mass percentage of Yb2O3 is 5%-6%, and the mass percentage of Gd2O3 is 4.7%-5.7%.

2. The thermal barrier coating according to claim 1, characterized in that, The adhesive layer includes a first adhesive layer and a second adhesive layer. The first adhesive layer is composed of Co, Ni, Cr, Al and Y, and by mass percentage contains 31%-33% Ni, 20%-22% Cr, 7%-9% Al and 0.5%-1% Y, with the balance being Co and unavoidable impurities. The particle size of the raw material powder for the first adhesive layer is 22μm-45μm, and the thickness of the first adhesive layer is 240μm-300μm. The material composition of the second adhesive layer includes Co, Ni, Cr, Al and Y, and by mass percentage it contains 30%-33% Ni, 20%-22% Cr, 6%-9% Al and 0.5%-1% Y, with the balance being Co and unavoidable impurities. The particle size of the raw material powder of the first adhesive layer is 45μm-90μm, and the thickness of the second adhesive layer is 55μm-65μm.

3. The thermal barrier coating according to claim 1, characterized in that, include, The thickness of the first ceramic heat insulation layer is 225μm-275μm; The thickness of the second ceramic heat insulation layer is 230μm-270μm.

4. The thermal barrier coating according to claim 1, characterized in that, include, The combined thickness of the first ceramic insulation layer and the second ceramic insulation layer is 470μm-520μm.

5. The thermal barrier coating according to claim 1, characterized in that, include, The porosity deviation between the first ceramic insulation layer and the second ceramic insulation layer is 1%-4%.

6. The thermal barrier coating according to claim 1, characterized in that, include, The powder used for the sacrificial coating is La. 0.5 Yb 0.5 Zr2O7 powder.

7. The thermal barrier coating according to claim 6, characterized in that, include, The diameter of the sprayed powder is 15μm-20μm.

8. The thermal barrier coating according to claim 1, characterized in that, include, The thickness of the sacrificial coating is 15μm-30μm.

9. The thermal barrier coating according to claim 1, characterized in that, include, The surface roughness Ra of the sacrificial coating is 1.19 μm-1.2 μm.

10. A method for preparing a thermal barrier coating for a high-temperature alloy surface as described in claim 1, wherein the thermal barrier coating comprises, from near to far, an adhesive layer, a first ceramic insulating layer, a second ceramic insulating layer, and a sacrificial coating, characterized in that, include: S1: Using a spraying device, the raw material powder is sprayed onto the surface of the high-temperature alloy to a preset thickness to complete the spraying of the adhesive layer. The adhesive layer is then sandblasted to improve its surface roughness. S2: Use a spraying device to spray the first ceramic heat insulation layer at the interface of the adhesive layer. In at least the last spraying, change the spraying angle to complete the spraying of the first ceramic heat insulation layer. Sandblast the first ceramic heat insulation layer to improve the surface roughness. Use a plasma flame to preheat the surface of the first ceramic heat insulation layer. After reaching the preheating temperature, spray the second ceramic heat insulation layer according to a predetermined path. S3: Apply the sacrificial coating.

11. The method according to claim 10, characterized in that, Step S1 further includes: First, the first adhesive layer is applied using supersonic flame spraying to achieve the preset thickness. Then, the second adhesive layer is applied using atmospheric plasma spraying.

12. The method according to claim 10, characterized in that, Step S1 further includes: After the adhesive layer is applied, an aging heat treatment is performed.

13. The method according to claim 12, characterized in that, Step S1 includes: After the aging heat treatment is completed, the areas that need to be masked are masked, the tooling fixtures are installed and the spraying program is adjusted, and the dry ice sandblasting method with particles of 3mm-5mm is adopted for sandblasting.

14. The method according to claim 10, characterized in that, Step S2 further includes: In the last one or two coats of the first ceramic insulation layer, the spray gun angle is changed from 90 degrees perpendicular to the surface to 60-80 degrees for spraying.

15. The method according to claim 10, characterized in that, Step S2 further includes: After the first ceramic heat insulation layer is sprayed, different sandblasting pipes are used to sandblast the surface of the first ceramic heat insulation layer together with 20-60 mesh fused zirconium crushed sand and dry ice with a particle diameter of 3mm-5mm as sandblasting media.

16. The method according to claim 10, characterized in that, Step S2 further includes: The temperature of the first ceramic insulation layer is preheated to 200℃-500℃.

17. The method according to claim 10, characterized in that, Step S3 further includes: When spraying the sacrificial coating, the spraying distance is 80mm-120mm and the powder feeding speed is 48g / min-52g / min.

18. The method according to claim 10, characterized in that, Step S3 further includes: After the sacrificial coating is applied, the surface of the sacrificial coating is polished.

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