A thermal barrier coating with high thermal insulation and resistance to CMAS corrosion and its preparation method

Abstract

This invention relates to a thermal barrier coating with high thermal insulation and resistance to CMAS corrosion. From top to bottom, it comprises a ceramic layer, a metal bonding layer, and a high-temperature alloy substrate. The ceramic layer is a layered structure composed of a dense CMAS corrosion-resistant layer and a thermal insulation layer formed by the regular arrangement of porous particle clusters. This invention also relates to a method for preparing the above-mentioned thermal barrier coating, which utilizes atmospheric plasma spraying to deposit the ceramic layer. The CMAS corrosion-resistant layer is formed by fully melting and stacking hollow spherical ceramic powder through a plasma jet. Simultaneously, porous agglomerated ceramic powder is injected into the plasma to form a thermal insulation layer, ultimately producing a coating structure with alternating CMAS corrosion-resistant and thermal insulation layers. The thermal barrier coating of this invention overcomes the mutual constraint between CMAS corrosion resistance and thermal insulation capabilities in conventional layered and disordered porous thermal barrier coatings, exhibiting excellent high-temperature thermal life.

Description

Technical Field

[0001] This invention relates to thermal barrier coatings, and more specifically to a thermal barrier coating with high thermal insulation and resistance to CMAS corrosion, and a method for preparing the same. Background Technology

[0002] Thermal barrier coatings (TBCs) have been widely used on the surfaces of hot-end components in advanced gas turbines and aero engines to reduce surface temperatures and mitigate damage to metal components caused by high-temperature operating environments. This allows engines to operate safely under more demanding conditions by increasing gas temperatures. A complete TBC system typically consists of a high-temperature alloy substrate, an intermediate binder layer, and a top ceramic layer. The performance of the top ceramic layer has a crucial impact on the performance of the TBC system. Materials used as TBC ceramic layers generally need to possess characteristics such as low thermal conductivity, high phase stability, and excellent high-temperature thermophysical properties. However, in practical applications, fully utilizing the material's performance advantages relies on advanced coating preparation techniques and the design of different coating structures.

[0003] The principle of thermal barrier coating (TBC) structure design is to ensure that the prepared coating structure possesses high-temperature corrosion resistance, high compliance, sintering resistance, and low thermal conductivity. Mainstream TBC preparation technologies primarily include electron beam physical vapor deposition (EB-PVD) and atmospheric plasma spraying (APS). Different microstructures of TBC are designed to meet various requirements. Among these, APS technology has become the most widely used TBC preparation technology due to its lower cost and high flexibility in process parameter control. TBC prepared using APS technology contains a large number of two-dimensional unbonded interlayer pores and some spherical pores. The presence of these pore structures can effectively regulate the strain tolerance of the coating during service and reduce the thermal conductivity of the TBC system, thus improving the service performance of the TBC. However, these pore structures are often easily filled by molten CMAS at high temperatures, thereby accelerating coating sintering and hardening, reducing the strain tolerance of the TBC system, and causing coating cracking and failure.

[0004] Current research both domestically and internationally indicates that the overall service performance of a TBC system can be optimized through pore structure design. Based on APS technology, researchers have conducted studies to adjust the pore structure of APS TBCs by controlling deposition parameters such as plasma power, spraying distance, and spraying angle. However, these methods have limitations: they can only adjust the total porosity level of the coating, making it difficult to control the pore distribution and geometry. The pores remain diffusely distributed within the coating, and their geometry is uncontrollable. Furthermore, the geometry and distribution of the pores are directly related to the mechanical, thermal insulation, and corrosion resistance properties of the TBC.

[0005] In conclusion, there is an urgent need to develop a coating deposition technique based on APS technology to control the microstructure and distribution of pores in thermal barrier coatings (TBCs). This will facilitate high-performance TBCs in service and meet the increasingly stringent requirements for thermal barrier coatings in aerospace and other fields. Summary of the Invention

[0006] To address the problems in the prior art where pores are still diffusely distributed in the coating and their geometry is uncontrollable, this invention provides a thermal barrier coating with high thermal insulation and resistance to CMAS corrosion (also known as an APS thermal barrier coating with a regularly arranged CMAS corrosion-resistant layer and thermal insulation layer) and its preparation method.

[0007] The thermal barrier coating with high thermal insulation and CMAS corrosion resistance according to the present invention is composed of a ceramic layer, a metal bonding layer and a high-temperature alloy substrate from top to bottom. The ceramic layer is a layered structure composed of a dense CMAS corrosion resistant layer and a thermal insulation layer formed by the regular arrangement of porous particle clusters.

[0008] Preferably, the ceramic layer is formed by alternating layers of CMAS corrosion-resistant layers and linearly arranged porous agglomerated ceramic powder insulation layers. That is, the ceramic layer is divided into CMAS corrosion-resistant layers and insulation layers by linearly arranged porous particle clusters, exhibiting a regular reciprocating structure of dense CMAS corrosion-resistant layers and loose insulation layers.

[0009] Preferably, the thickness of the ceramic layer is 200μm to 1000μm.

[0010] Preferably, the density of the CMAS corrosion-resistant layer is >80%, and the thickness is 30μm to 50μm.

[0011] Preferably, the heat insulation layer is formed by a horizontally linear arrangement of several porous agglomerated ceramic powder clusters embedded in the CMAS corrosion-resistant layer, and the heat insulation layer is perpendicular to the heat flow direction. Because the heat insulation layer is perpendicular to the heat flow direction, the heat insulation performance of the coating can be effectively improved.

[0012] Preferably, the density of the insulation layer is <50%, and the thickness is 5μm to 20μm.

[0013] According to the above-described method for preparing the thermal barrier coating of the present invention, the ceramic layer is deposited by atmospheric plasma spraying. The anti-CMAS corrosion layer is formed by stacking hollow spherical ceramic powder after it has been fully melted by a plasma jet. Simultaneously, porous agglomerated ceramic powder is injected into the plasma to form a thermal insulation layer, ultimately resulting in a coating structure with alternating anti-CMAS corrosion layers and thermal insulation layers. In other words, the ceramic layer achieves a thermal barrier coating with a regularly arranged anti-CMAS corrosion layer and thermal insulation layer simultaneously during the coating preparation process by controlling the powder injection method.

[0014] Preferably, the preparation method includes: S1, surface sandblasting treatment of the high-temperature alloy substrate, ultrasonic cleaning and drying after surface roughening; S2, preparation of a metal bonding layer on the surface of the roughened high-temperature alloy substrate using APS technology; S3, injection of easily fully meltable hollow spherical ceramic powder into the center of the plasma flow, which, after being heated and accelerated by plasma, impacts the surface of the metal bonding layer to form a layered stacked layer; and coaxial conveying of porous agglomerated ceramic powder into the end of the plasma flow, which is then carried and dispersed into the layered stacked layer by plasma to form a loose porous coating structure.

[0015] Preferably, during the preparation of the ceramic layer, the spray gun scanning linear speed is 600-800 mm / s, the grating scanning step size is 1-2 mm, and the porous agglomerated ceramic powder feeding rate is 30-40 g / min.

[0016] Preferably, the hollow spherical ceramic powder and the porous agglomerated ceramic powder are selected from at least one of zirconium oxide, yttrium-stabilized zirconium oxide, ytterbium-stabilized zirconium oxide, dual rare earth doped modified zirconium oxide, gadolinium zirconate, lanthanum zirconate, strontium zirconate, and lanthanum cerate.

[0017] Preferably, during the preparation of the ceramic layer, the spraying power is 38KW to 42KW, the spray gun current is 550A to 650A, the main gas flow rate is 40slpm to 50slpm, and the auxiliary gas flow rate is 8slpm to 10slpm.

[0018] Preferably, the anti-CMAS corrosion layer is formed by spreading and stacking several fully molten hollow spherical ceramic powder droplets.

[0019] Preferably, the anti-CMAS corrosion layer is made by injecting hollow spherical ceramic powder with a particle size of 10μm to 40μm.

[0020] Preferably, the feeding rate of the hollow spherical ceramic powder is 10-20 g / min. In a preferred embodiment, the powder flowability of the hollow spherical ceramic powder is 90 sec / 50 g.

[0021] Preferably, the internal grain size of the hollow spherical ceramic powder is 50–300 nm.

[0022] Preferably, the injection position of the hollow spherical ceramic powder is 5 mm away from the horizontal distance of the plasma flame outlet, and the powder is fully melted and spread onto the substrate by the high temperature and high energy plasma at the plasma flame outlet to form a dense layer.

[0023] Preferably, the heat insulation layer is made of porous agglomerated ceramic powder with a particle size of 30μm to 60μm. In a preferred embodiment, the flowability of the porous agglomerated ceramic powder is 152 sec / 50g.

[0024] Preferably, the internal agglomerated particle size of the porous agglomerated ceramic powder is 1μm to 8μm.

[0025] Preferably, the injection position of the porous agglomerated ceramic powder is 35 mm away from the horizontal distance of the sub-flame outlet, so that the porous ceramic powder is embedded into the coating and its original structure is maintained in a region far away from the high temperature and high energy range of the plasma flame.

[0026] The thermal barrier coating with high thermal insulation and resistance to CMAS corrosion according to the present invention is suitable for the surface of hot-end components such as gas turbines and aero engines.

[0027] The thermal barrier coating of the present invention features a regularly arranged CMAS corrosion-resistant layer and a thermal insulation layer, overcoming the mutual constraint between the CMAS corrosion resistance and thermal insulation capabilities of conventional layered and disordered porous thermal barrier coatings, thus exhibiting excellent high-temperature thermal life. The preparation method of the thermal barrier coating according to the present invention has low process cost and high design flexibility, allowing for economical and efficient control of the thermal barrier coating structure in practical applications. Furthermore, the present invention utilizes simple and economical process control measures to overcome the mutual constraint between the thermal insulation capability and CMAS corrosion resistance of disordered porous TBC structures, thereby achieving a thermal barrier coating structure design that synergistically combines low thermal conductivity, long life, and CMAS corrosion resistance, solving the aforementioned technical barriers that urgently need to be addressed in thermal barrier coatings. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of an APS thermal barrier coating with a regularly arranged anti-CMAS corrosion layer and thermal insulation layer according to the present invention.

[0029] Figure 2a This is the microstructure of the APS thermal barrier coating with a regularly arranged anti-CMAS corrosion layer and thermal insulation layer prepared in Example 1;

[0030] Figure 2b The cross-sectional microstructure of the disordered porous APS coating prepared in Comparative Example 1 is shown.

[0031] Figure 2c The cross-sectional microstructure of the traditional layered APS coating prepared in Comparative Example 2 is shown.

[0032] Figure 3 This paper compares the flame thermal shock lifetime of the CMAS corrosion-resistant layer-insulation layer with the regularly arranged coating, the disordered porous APS coating, and the traditional layered APS coating prepared in Example 2 of this invention.

[0033] Figure 4a The thermal diffusivity of the CMAS corrosion-resistant layer-insulation layer prepared in Example 3 of this invention is compared with that of the disordered porous APS coating and the traditional layered APS coating.

[0034] Figure 4b The thermal conductivity of the regularly arranged anti-CMAS corrosion layer-insulation layer coating prepared in Example 3 of this invention is compared with that of the disordered porous APS coating and the traditional layered APS coating.

[0035] Figure 5a The microstructure of the coating with a regular arrangement of anti-CMAS corrosion layer and heat insulation layer prepared in Example 4 of this invention after CMAS corrosion for 4 hours is shown.

[0036] Figure 5b The microstructure of the disordered porous APS coating prepared in Example 4 of this invention after CMAS etching for 4 hours is shown.

[0037] Figure 5c The microstructure of the traditional layered APS coating prepared in Example 4 of this invention is shown after CMAS etching for 4 hours. Detailed Implementation

[0038] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the content of the present invention is not limited to the content involved in the embodiments.

[0039] like Figure 1 As shown, the high thermal insulation and CMAS corrosion resistant APS thermal barrier coating according to the present invention comprises a high-temperature alloy substrate 1 located at the bottom layer.

[0040] The high thermal insulation and CMAS corrosion resistant APS thermal barrier coating according to the present invention includes a metal bonding layer 2 bonded to a high-temperature alloy substrate 1. In a preferred embodiment, the metal bonding layer 2 is made of NiCrAlY or NiCoCrAlY and has a thickness of 100 μm to 200 μm.

[0041] The high thermal insulation and CMAS corrosion resistant APS thermal barrier coating according to the present invention comprises a ceramic layer 3 bonded to a metal bonding layer 2. In a preferred embodiment, the ceramic layer 3 comprises a plurality of CMAS corrosion resistant layers 4 and thermal insulation layers 5 arranged linearly perpendicular to the heat flow direction, wherein the CMAS corrosion resistant layers 4 and the thermal insulation layers 5 are alternately formed in the ceramic layer 3. Figure 1 For example, the heat flow direction is up and down, and the insulation layer is distributed on the horizontal plane.

[0042] In a preferred embodiment, each CMAS corrosion-resistant layer 4 has a thickness of 30 μm to 50 μm, is formed by stacking several fully molten lamellar units, has a density >80%, and a porosity <5%.

[0043] In a preferred embodiment, the thickness of each insulation layer 5 is 5μm to 20μm, and the porous particle clusters can achieve a regular linear arrangement, thereby forming a loosely arranged insulation layer with a density of <50%. It should be understood that the porous particle clusters can be laid flat on the anti-CMAS corrosion layer 4 at a 0° angle, or they can be laid flat on the anti-CMAS corrosion layer 4 with a small angle (e.g., 20°) that is slightly raised. It should be understood that this angle can be between 0° and 30°.

[0044] This invention is based on APS coating deposition technology. By improving the powder injection method and controlling the spraying parameters, a high-insulation and CMAS-resistant APS thermal barrier coating is prepared. Specifically, it includes the following steps: synchronously controlling the spray gun grating scanning step size, scanning linear speed and powder feeding ratio to control the thickness of the sheet stack layer to 30μm~50μm and the density >80%, forming a CMAS-resistant layer 4; controlling the regular arrangement of porous cluster units perpendicular to the heat flow direction to form a loosely arranged, approximately horizontally arranged thermal insulation layer 5 with a density <50%.

[0045] Specifically, the hollow spherical ceramic powder and porous agglomerated ceramic powder materials required for depositing the ceramic layer 3 of the present invention include, but are not limited to, at least one of zirconium oxide, yttrium partially stabilized zirconium oxide, ytterbium stabilized zirconium oxide, dual rare earth doped modified zirconium oxide, gadolinium zirconate, lanthanum zirconate, strontium zirconate, and lanthanum cerate.

[0046] Thermal barrier coatings composed of layered structural units formed using existing APS technology typically exhibit preferential strain tolerance but limited thermal insulation performance. While porous thermal barrier coatings prepared using APS technology can effectively improve strain tolerance and reduce thermal conductivity to some extent by introducing pores and unmelted particles, CMAS corrosive media can easily penetrate the coating through randomly distributed pores and unmelted particles, rapidly destroying the coating structure and leading to rapid failure. Therefore, it is difficult to obtain thermal barrier coatings with low thermal conductivity, high strain tolerance, and resistance to CMAS corrosion using existing APS technology. This invention utilizes existing APS technology, by improving the powder feeding method and controlling the spraying process parameters, to design an APS thermal barrier coating with a regularly arranged CMAS corrosion-resistant layer and thermal insulation layer, overcoming the mutual constraint between thermal insulation and CMAS corrosion resistance in single layered structures and disordered porous coating structures. It ensures both low thermal conductivity and high strain tolerance while also maintaining good CMAS corrosion resistance. On the other hand, the method provided by this invention has low equipment dependence and can optimize the design of thermal barrier coating structures simply and economically.

[0047] Example 1

[0048] The high-temperature alloy substrate 1 is made of the currently mainstream In738 nickel-based high-temperature alloy, with a thickness of 3mm. First, the high-temperature alloy substrate 1 is roughened by sandblasting. The sandblasting medium is 200-mesh corundum particles, and the sandblasting pressure is 0.2MPa~0.3MPa. The resulting substrate surface roughness is 5Ra~6Ra.

[0049] A metal binder layer 2 was deposited on the surface of the roughened high-temperature alloy substrate 1 using APS technology. The material used for the metal binder layer 2 was NiCoCrAlY, with a particle size range of 37.5 μm to 60 μm. First, the surface of the high-temperature alloy substrate 1 was preheated using plasma at a temperature of 300℃ to 500℃. During the deposition of the metal binder layer 2, the APS spray gun current was 450A to 500A, the main gas flow rate was 55 slpm to 60 slpm, the auxiliary gas flow rate was 6 slpm to 7 slpm, the power was maintained at 33KW to 36KW, the spraying distance was 120mm to 150mm, and the spray gun movement speed was controlled at 1000mm / s.

[0050] During the deposition of ceramic layer 3, the plasma spray gun current was 550A–650A, the main gas flow rate was 40–50 slpm, the auxiliary gas flow rate was 8–10 slpm, and the power was maintained at 38 kW–42 kW. The thickness of ceramic layer 3 was 200 μm–1000 μm.

[0051] The sample with the metal binder layer 2 deposited was fixed using a fixture, and a ceramic layer 3 was prepared using an APS (Automatic Plasma Stamping) device. To obtain a high-density CMAS corrosion-resistant layer 4, hollow spherical ceramic powder with an internal grain size of 50–300 nm, a particle size of 10 μm–40 μm, and a flowability of 90 sec / 50 g was used. This powder was injected into the plasma center at a horizontal distance of 5 mm from the plasma flame outlet at a feed rate of 10–20 g / min. After plasma melting, accelerated impact, and solidification on the surface of the binder layer, lamellar units 6 were formed. Several lamellar units 6 were stacked to form the CMAS corrosion-resistant layer 4. In order to simultaneously form a porous heat insulation layer 5 in the ceramic layer 3, a modified powder feeding device is used to inject porous agglomerated ceramic powder 7 with an internal agglomerated particle size of 1μm to 8μm, a particle diameter of 30μm to 60μm, and a flowability of 152sec / 50g into the plasma tail end by coaxial conveying. The injection position of the porous agglomerated ceramic powder 7 is kept at a horizontal distance of 35mm from the plasma flame outlet. After being carried by the plasma, the powder is dispersed in the ceramic layer 3.

[0052] The scanning step size and scanning linear velocity of the plasma flame arc grating are controlled by a robotic arm via a program. The scanning linear velocity is controlled at 600-800 mm / s, and the grating scanning step size is controlled at 1-2 mm. Simultaneously, the feeding rate of porous agglomerated ceramic powder 7 is controlled at 30-40 g / min. With a low grating scanning step size, high scanning linear velocity, and high feeding rate of porous agglomerated ceramic powder, the porous cluster units can be linearly arranged in the ceramic layer to form a porous heat insulation layer 5 with a thickness of 5 μm to 20 μm, a density of <50%, and perpendicular to the heat flow direction. Simultaneously, the above operations can also simultaneously control the thickness of the CMAS corrosion-resistant layer 4 to reach 30 μm to 50 μm and a density of >80%.

[0053] like Figure 2a As shown, the prepared TBC exhibits distinct microstructural features. Within the high-density CMAS corrosion-resistant layer 4, regularly arranged transverse porous particle clusters are distributed, forming a porous thermal insulation layer 5. Furthermore, the thermal insulation layer 5 and the CMAS corrosion-resistant layer 4 are alternately arranged to form an APS thermal barrier coating with a regularly arranged CMAS corrosion-resistant layer and thermal insulation layer.

[0054] Comparative Example 1

[0055] The difference between this comparative example and Example 1 is that the plasma arc scanning linear velocity is 500 mm / s, the grating scanning step size is 3 mm, and the feeding rate of the porous agglomerated ceramic powder 7 is 20 g / min. Figure 2b As shown, the thermal barrier coating in Comparative Example 1 exhibits a loose, porous structure with randomly distributed particles. Furthermore, the overall density of the coating is lower compared to Example 1.

[0056] Comparative Example 2

[0057] The difference between this comparative example and Example 1 is that the plasma arc scanning linear velocity is 500 mm / s, the grating scanning step size is 3 mm, a conventional APS powder feeding device is used, and the feeding rate of porous agglomerated ceramic powder 7 is 0 g / min. The microstructure of the coating prepared in Comparative Example 2 is as follows: Figure 2c As shown, it exhibits a typical APS layered structure in its microstructure.

[0058] Example 2

[0059] An APS thermal barrier coating with a regularly arranged anti-CMAS corrosion layer and thermal insulation layer was prepared according to Example 1. Disordered porous structure and conventional structure thermal barrier coatings were prepared according to Comparative Example 1 and Comparative Example 2, respectively. Flame thermal shock performance tests were conducted on these three coatings.

[0060] The specific steps are as follows: The sample is fixed on a flame thermal shock testing machine using a fixture. Oxygen is used as the combustion-supporting gas and propane as the fuel. A stable flame with high temperature and high velocity is obtained through combustion. The specific testing conditions are: the sample surface temperature rises to 1400℃~1450℃ within 50 seconds, is held at this temperature for 70 seconds, and then cooled with compressed air for 120 seconds. This heating-cooling process is considered as one cycle. When the area of ​​coating peeling off the sample surface reaches 10%, the coating is considered to have failed. Two parallel samples are selected for testing for each coating structure to reduce error.

[0061] like Figure 3 As shown, the high heat insulation and CMAS corrosion resistant APS thermal barrier coating prepared in Example 1 has the highest flame thermal shock life, up to 68 cycles; the highest flame thermal shock life of Comparative Example 1 is 44 cycles; and the highest flame thermal shock life of Comparative Example 2 is only 17 cycles.

[0062] Example 3

[0063] APS thermal barrier coatings with high thermal insulation and resistance to CMAS corrosion were prepared according to Example 1. Disordered porous structures and conventional structures of thermal barrier coatings were prepared according to Comparative Examples 1 and 2, respectively. The thermal insulation performance of these three coatings was tested. The thermal diffusivity of the samples was measured using a laser thermal conductivity meter, and the thermal conductivity of the samples was calculated by combining the Archimedes' displacement method to determine the density and specific heat capacity, thereby evaluating the thermal insulation performance of the samples.

[0064] like Figure 4a As shown, the thermal diffusivity of all coating samples gradually decreased with increasing test temperature. The thermal barrier coating with high thermal insulation and CMAS corrosion resistance prepared in Example 1 exhibited the lowest thermal diffusivity, with a thermal diffusivity of only 0.22 mm at 1000°C. 2 / s, the disordered porous coating prepared in Comparative Example 1 has a thermal diffusivity of 0.37 mm at 1000℃. 2 / s, the traditional layered coating prepared in Comparative Example 2 has a thermal diffusivity of 0.48 mm at 1000℃. 2 / s.

[0065] like Figure 4b As shown, the thermal barrier coating with high thermal insulation and CMAS corrosion resistance prepared in Example 1 exhibits the lowest thermal conductivity, with a value of only 0.96 W / m / K (1000℃). The thermal conductivity of the disordered porous structure coating prepared in Comparative Example 1 is 1.13 W / m / K (1000℃), and the thermal conductivity of the conventional layered structure coating prepared in Comparative Example 2 is 1.59 W / m / K (1000℃).

[0066] Example 4

[0067] An APS thermal barrier coating with a regularly arranged CMAS corrosion-resistant layer and thermal insulation layer was prepared according to Example 1. Disordered porous structure and conventional structure thermal barrier coatings were prepared according to Comparative Examples 1 and 2, respectively. The CMAS corrosion resistance of these three coatings was tested. The CMAS powder composition was 35CaO-4MgO-11AlO 1.5 -46SiO 2 After ball milling, the mixed powder was placed in a muffle furnace and held at 1550℃ for 4 hours to generate a solid-state reaction. To ensure homogeneity, the resulting glassy CMAS melt was then ball-milled for 12 hours at ambient temperature. The CMAS powder was mixed with ethanol to form a slurry, and then... 2 The area density of CMAS powder is applied to the surface of the sample, and then the sample coated with CMAS powder is placed in a muffle furnace and kept at 1300℃ for 4 hours. The sample is then removed after being cooled in the furnace.

[0068] like Figure 5a As shown in the figure, the cross-sectional morphology of the thermal barrier coating with high heat insulation and CMAS corrosion resistance prepared in Example 1 after CMAS corrosion at 1300℃ for 4 hours is shown. It can be seen from the figure that the corrosion depth of the coating is about 300 μm.

[0069] like Figure 5b As shown, the disordered porous structure prepared in Comparative Example 1 was corroded by CMAS at 1300℃ for 4 hours, and the corrosion products basically penetrated through the coating thickness direction, with a penetration depth of about 700 μm.

[0070] like Figure 5c As shown, the traditional layered thermal barrier coating prepared in Comparative Example 2 has a corrosion depth of approximately 500 μm after being etched by CMAS at 1300 °C for 4 h.

[0071] The results of the above embodiments demonstrate that the APS thermal barrier coating with a regularly arranged anti-CMAS corrosion layer and thermal insulation layer proposed in this invention, based on APS technology, exhibits excellent high-temperature service performance. Furthermore, this method achieves synergistic optimization among the thermal barrier coating's long lifespan, high thermal insulation, and high resistance to CMAS corrosion. This method allows for the regular control of unmelted particles in the thermal barrier coating, is simple to operate, and has low cost, enabling economical and efficient control of the thermal barrier coating structure in practical applications.

[0072] The above embodiments are only used to further illustrate the design concept and technical solution of the present invention, and are not intended to limit the scope of the present invention. Any modifications or substitutions made based on the claims and description of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a thermal barrier coating, characterized in that, The thermal barrier coating consists of a ceramic layer, a metal binder layer, and a high-temperature alloy substrate from top to bottom. The preparation method utilizes atmospheric plasma spraying to deposit the ceramic layer. Specifically, the scanning linear velocity of the plasma spray gun is controlled at 800 mm / s, while the grating scanning step size is controlled at 1-2 mm. Hollow spherical ceramic powder with a particle size of 10 μm to 40 μm and an internal grain size of 50 to 300 nm is injected into the plasma center at a feed rate of 10-20 g / min, and fully melted by the plasma jet. After processing, a CMAS corrosion-resistant layer with a density >80% is formed by stacking porous agglomerated ceramic powder with a particle size of 30μm~60μm and an internal agglomerated particle size of 1μm~8μm. The powder is simultaneously injected into the plasma tail end by coaxial conveying at a feeding rate of 40g / min to form porous agglomerated ceramic powder into porous cluster units. The porous cluster units are linearly arranged in the ceramic layer to obtain a heat insulation layer with a density <50%. Finally, a coating structure with alternating CMAS corrosion-resistant layer and heat insulation layer is produced.

2. The preparation method according to claim 1, characterized in that, The preparation method includes: S1, the surface of the high-temperature alloy substrate is subjected to surface sandblasting treatment, and after surface roughening, the high-temperature alloy substrate is ultrasonically cleaned and then dried. S2, A metal bonding layer is prepared on the surface of the roughened high-temperature alloy substrate using APS technology; S3, hollow spherical ceramic powder that is easy to melt is injected into the center of the plasma flame. After being heated and accelerated by the plasma, it impacts the surface of the metal bonding layer to form a layered stacked layer. Through coaxial conveying, porous agglomerated ceramic powder is injected into the end of the plasma flame. After being carried and dispersed by the plasma into the layered stacked layer, a loose porous coating structure is formed.

3. The thermal barrier coating with high thermal insulation and resistance to CMAS corrosion obtained by the preparation method according to claim 1 or 2, characterized in that, The ceramic layer is a layered structure composed of an alternating dense CMAS corrosion-resistant layer and a thermal insulation layer formed by regularly arranged porous particle clusters. The thickness of the ceramic layer is 200μm~1000μm, the thickness of the CMAS corrosion-resistant layer is 30μm~50μm, and the thickness of the thermal insulation layer is 5μm~20μm.

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