YSZ thermal barrier coating with controllable non-through pore structure and preparation method of YSZ thermal barrier coating

Abstract

The invention discloses a YSZ thermal barrier coating with a controllable non-through pore structure and a preparation method of the YSZ thermal barrier coating, the YSZ thermal barrier coating is formed by YSZ ceramic composite powder through plasma spraying, and the YSZ ceramic composite powder is formed by mixing the following components in percentage by mass: 20-30% of nanocrystalline agglomerated YSZ powder, 20-30% of nanocrystal agglomerated YSZ powder, 5-10% of nanocrystal agglomerated YSZ powder, 5-10% of nanocrystal agglomerated YSZ powder, 5-10% of nanocrystal agglomerated YSZ powder, 5-10% of nanocrystal Micron YSZ (Yttria Stabilized Zirconia) powder accounting for 20 to 30 percent; hollow spherical YSZ (Yttria Stabilized Zirconia) powder accounting for 40%-60%; the porosity of the coating ranges from 6% to 12%, the pore structure is non-through, and pores are distributed in an isolated mode and are not communicated. According to the preparation method, the nanocrystalline agglomerated YSZ powder, the micron YSZ powder and the hollow spherical YSZ powder are mixed, a porous coating microstructure with non-communicated pores is realized through a plasma spraying technology, and the prepared coating has excellent heat resistance, comprehensive mechanical properties and good economical efficiency.

Description

Technical Field

[0001] This invention relates to the technical field of preparing thermal barrier coatings, specifically a YSZ thermal barrier coating with a controllable non-penetrating pore structure and its preparation method. Background Technology

[0002] Thermal barrier coatings (TBCs) are a key high-temperature protection technology, widely used on the surfaces of hot-end components such as aero-engines, gas turbines, and automotive engines. By coating with a ceramic layer with low thermal conductivity, TBCs can effectively reduce the substrate temperature and improve the service life and efficiency of components. Among them, yttrium-stabilized zirconia (YSZ) is the most commonly used thermal barrier coating material due to its high melting point, good matching coefficient of thermal expansion, and excellent thermal stability.

[0003] Traditional YSZ coatings are typically prepared using atmospheric plasma spraying (APS) technology to form a layered structure. However, defects such as internal pores, microcracks, and unmelted particles not only impart low thermal conductivity to the coating but also affect its mechanical properties and long-term reliability. With the increasing demands for thermal insulation and durability in high-temperature components, optimizing the coating's microstructure to achieve a synergistic improvement in both thermal insulation and strength has become a key technical challenge in this field.

[0004] Currently, researchers are improving the performance of YSZ coatings through powder structure design and process innovation. Patent CN114075086A discloses a hollow yttrium-stabilized zirconia powder, its preparation method, and its applications. This technology uses sodium stearate as a pore-forming agent to prepare thin-shell hollow YSZ powder for coating to reduce thermal conductivity. Patent CN120945311A discloses a partially yttrium-stabilized zirconia powder with a multi-morphological porous structure and its preparation method. This method uses a pore-forming agent (such as starch) and slurry to control the preparation of a multi-level porous structure powder (including pores formed by the pore-forming agent and pores between nanoparticles) to improve the high-temperature stability of the coating. Furthermore, the coating exhibits a small increase in elastic modulus after heat exposure, demonstrating high pore structure stability.

[0005] However, current coatings typically exhibit a layered microstructure, containing pores, microcracks, and incompletely melted particles. These microscopic defects significantly reduce the thermal conductivity of the coating and affect its mechanical properties. Although existing technologies recognize the importance of controlling the pore structure, obtaining a YSZ thermal barrier coating that combines excellent thermal insulation and mechanical properties remains a technical challenge in this field.

[0006] To optimize the coating structure, researchers have experimented with YSZ powders with different structures. For example, using nanocrystalline agglomerated YSZ powder to prepare thermal barrier coatings can refine the grains and improve the coating density, but it is difficult to introduce a large number of non-connected pores. Hollow spherical YSZ powder can effectively introduce pores and reduce thermal conductivity, but it may form too many large-sized pores or cracks, impairing the mechanical properties of the coating. Therefore, developing a YSZ thermal barrier coating with a controllable non-connected pore structure is of great significance. Summary of the Invention

[0007] This application provides a YSZ thermal barrier coating with a controllable non-interconnected pore structure and its preparation method. The method involves mixing nanocrystalline aggregated YSZ powder, micron-sized YSZ powder and hollow spherical YSZ powder, and then using plasma spraying technology to achieve a porous coating microstructure with non-interconnected pores. The prepared coating has excellent heat resistance and is economical.

[0008] This application provides a YSZ thermal barrier coating with a controllable non-penetrating pore structure. The YSZ thermal barrier coating is formed by plasma spraying of YSZ ceramic composite powder. The YSZ ceramic composite powder comprises the following components mixed in the following mass percentages: nanocrystalline aggregated YSZ powder, accounting for 20%–30%; micron-sized YSZ powder, accounting for 20%–30%; and hollow spherical YSZ powder, accounting for 40%–60%. The porosity of the coating is 6%–12%, and the pore structure is non-penetrating, with pores distributed in isolation and not interconnected.

[0009] By adopting the above technical solution, the YSZ thermal barrier coating in this application is formed by plasma spraying of YSZ ceramic composite powder, wherein the YSZ ceramic composite powder includes nanocrystalline agglomerated YSZ powder, micron-sized YSZ powder, and hollow spherical YSZ powder. The blending of the three powders results in a non-penetrating porous structure after plasma spraying, that is, the pores exist in isolation and are not interconnected, ensuring the controllability of the structure. The hollow spherical YSZ powder used is prepared by an aeration-melting crushing-spheroidizing process. This process gives it a uniform and controllable hollow volume with a high proportion (50%-70%) and a high density (99.5%-99.9%) in the non-hollow part.

[0010] Specifically, the non-penetrating pore structure reduces crack propagation paths, thereby improving the mechanical strength of the coating while maintaining low thermal conductivity. In particular, the synergistic melting effect generated during spraying of this composite powder system significantly enhances the interlayer bonding strength of the coating, thus improving overall reliability. The resulting non-penetrating pore structure effectively suppresses the tendency for sintering densification under high-temperature conditions, which is beneficial for extending the service life of the coating. Furthermore, by precisely controlling the ratio of the three powders, their porosity and overall performance can be optimized, giving this coating system both excellent performance and promising prospects for industrial applications.

[0011] Specifically, during plasma spraying, nanocrystalline agglomerated YSZ powder undergoes preferential melting and rapid solidification due to its high surface energy, forming a dense grain boundary network. These grain boundaries act as a framework in the coating, providing basic mechanical support. Micron-sized YSZ powder, as the filler phase, maintains a relatively stable molten state and fills the gaps in the framework formed by the nanoparticles, ensuring the continuity and density of the coating. The high proportion of hollow volume and extremely high density of the non-hollow portion allow the hollow spherical YSZ powder to melt its outer shell while remaining hollow inside during plasma spraying. When these particles impact the substrate, the hollow structure is flattened but not completely collapsed, forming isolated pores. When the three powders are mixed in a specific ratio, during the rapid melting-solidification process of plasma spraying, the isolated pores formed by the hollow powder are surrounded by the dense network of nano and micron powders, isolated from each other by a dense ceramic matrix. This achieves non-penetrating pores and allows for excellent bonding with the adhesive layer, significantly improving the overall performance of the coating.

[0012] Preferably, the particle size range of the nanocrystalline aggregated YSZ powder is 35μm–65μm, the particle size range of the micron-sized YSZ powder is 35μm–65μm, and the particle size range of the hollow spherical YSZ powder is 39μm–69μm. The preparation process of the hollow spherical YSZ powder is an aeration-melting-crushing-spheroidizing process. The hollow volume ratio of the hollow spherical YSZ powder is uniform and controllable: 50%-70%, and the density of the non-hollow part is 99.5%-99.9%.

[0013] By adopting the above-mentioned technical solution, this application optimizes the spraying process. Specifically, three powders are compounded, and a specific particle size combination is determined. During plasma spraying, this composite powder, based on the synergistic effect of the compounded components, combined with the hollow spherical powder produced by a unique preparation process and the optimized particle size matching, achieves more complete melting and more uniform deposition, effectively reducing unmelted particles. This not only significantly improves the overall density of the coating but also enhances its interlayer bonding strength. The specification points out that this unique composite powder combination helps to form a uniformly distributed non-penetrating porous structure, optimizing the overall performance of the coating.

[0014] On the other hand, this application provides a method for preparing a YSZ thermal barrier coating with a controllable non-penetrating pore structure, characterized by the following steps: S1, powder mixing step: mixing nanocrystalline agglomerated YSZ powder, micron-sized YSZ powder and hollow spherical YSZ powder in proportion, homogenizing the mixture, and then drying it in a vacuum drying oven to obtain YSZ ceramic composite powder; S2, adhesive layer preparation step: selecting a high-temperature alloy as the substrate, ultrasonically cleaning it, and then sandblasting the substrate surface; preparing a NiCoCrAlY adhesive layer on the substrate surface using plasma spraying technology, and then cleaning the adhesive layer surface; S3, ceramic layer preparation step: spraying the YSZ ceramic composite powder onto the NiCoCrAlY adhesive layer surface using plasma spraying technology, using compressed air to blow away the coating surface and control the thickness of the ceramic layer during the spraying process.

[0015] By adopting the above technical solution, this application first uses three powders to homogenize them through physical methods; then, a NiCoCrAlY bonding layer is prepared to alleviate the mismatch in thermal expansion coefficients between the ceramic layer and the metal substrate; finally, by controlling the parameters of plasma spraying technology, differentiated melting and deposition of the three powders are achieved.

[0016] Preferably, in step S1, the nanocrystalline agglomerated YSZ powder, the micron-sized YSZ powder, and the hollow spherical YSZ powder are mixed in a certain proportion and homogenized using a planetary ball mill with a ball-to-powder ratio of 8:1, a milling speed of 260 r / min, and a milling time of 4 h; the mixed powder is then dried in a vacuum drying oven at a temperature of 80℃–100℃ for 2 h–4 h.

[0017] Preferably, in step S2, Inconel 718 high-temperature alloy is selected as the substrate, and it is ultrasonically cleaned with anhydrous ethanol as the cleaning solution for 10 min–15 min. Then, the substrate surface is sandblasted.

[0018] Preferably, in step S2, a NiCoCrAlY bonding layer is prepared on the substrate surface using plasma spraying technology. The plasma spraying parameters include: power 30 kW–50 kW, argon as the powder feed gas, main gas flow rate 30 SLPM–40 SLPM, powder feed rate 20 g / min–40 g / min, spraying distance 100 mm–120 mm, compressed air cooling during the spraying process, and the bonding layer thickness is controlled to be 100 μm–200 μm. The bonding layer surface is then cleaned.

[0019] Preferably, in step S3, the YSZ ceramic composite powder is sprayed onto the surface of the NiCoCrAlY bonding layer using plasma spraying technology. The plasma spraying parameters include: power 40 kW–60 kW, argon as the powder feed gas, main gas flow rate 30 SLPM–40 SLPM, powder feed rate 30 g / min–50 g / min, spraying distance 150 mm–200 mm, and spray gun moving speed 10 mm / s–30 mm / s. During the spraying process, compressed air is used to blow away the coating surface to cool the coating, and the ceramic layer thickness is controlled to be 150 μm–300 μm, thus obtaining a YSZ thermal barrier coating with a controllable non-penetrating pore structure.

[0020] Preferably, in step S1, the hollow spherical YSZ powder is obtained by plasma spheroidization treatment of ordinary agglomerated YSZ powder.

[0021] Preferably, the hollow spherical YSZ powder is agglomerated by plasma spheroidization. The plasma spheroidization process has a power of 30-40kW and a powder feeding rate of 2-4kg / h. After natural cooling, the powder is sieved to obtain hollow spherical YSZ powder with a particle size of 39μm-69μm.

[0022] One or more technical solutions provided in this application have at least the following technical effects or advantages: 1. The YSZ thermal barrier coating in this application is formed by plasma spraying of YSZ ceramic composite powder, wherein the YSZ ceramic composite powder includes nanocrystalline agglomerated YSZ powder, micron-sized YSZ powder, and hollow spherical YSZ powder. The hollow spherical YSZ powder is prepared by an aeration-melting-crushing-spheroidizing process, exhibiting a high hollow volume ratio and high density in the non-hollow portions. The formulation of these three powders results in a non-penetrating porous structure after plasma spraying, i.e., the pores exist in isolation and are not interconnected, ensuring structural controllability. Furthermore, this composite powder system produces excellent synergistic melting during spraying, enabling the coating to achieve excellent bonding strength with the adhesive layer. Specifically, the non-penetrating porous structure reduces crack propagation paths, thereby improving the mechanical strength of the coating while maintaining low thermal conductivity. Additionally, the non-penetrating nature of the pores reduces the risk of densification during high-temperature sintering, extending service life.

[0023] 2. This application optimizes the spraying process by defining a specific particle size range that makes the powder easier to melt and deposit during plasma spraying, reducing unmelted particles, improving coating density, and resulting in high interlayer bonding strength. The specification states that this particle size combination contributes to the formation of a uniform pore distribution.

[0024] 3. This application first uses three powders to homogenize them through physical methods; then, a NiCoCrAlY bonding layer is prepared to alleviate the mismatch in thermal expansion coefficients between the ceramic layer and the metal substrate; finally, by controlling the parameters of plasma spraying technology, differentiated melting and deposition of the three powders are achieved. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 A schematic diagram of the microstructure of a YSZ thermal barrier coating with controllable non-penetrating porosity. Figure 2 Microscopic morphology (SEM) of hollow spherical YSZ ceramic powder; Figure 3 Microscopic morphology (SEM) of micron-sized YSZ ceramic powder; Figure 4 Microscopic morphology (SEM) of nanocrystalline aggregated YSZ ceramic powder; Figure 5 The surface microstructure (SEM) of the obtained YSZ thermal barrier coating with controllable non-penetrating porosity is shown. Figure 6 The microstructure (SEM) of the cross-section of the obtained YSZ thermal barrier coating with controllable non-penetrating porosity is shown. Detailed Implementation

[0027] This application provides a YSZ thermal barrier coating with a controllable non-interconnected pore structure and its preparation method. The method involves mixing nanocrystalline agglomerated YSZ powder, micron-sized YSZ powder and hollow spherical YSZ powder, and then using plasma spraying technology to achieve a porous coating microstructure with non-interconnected pores. The prepared coating has excellent heat resistance, comprehensive mechanical properties and good economic efficiency.

[0028] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0029] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or server that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or modules not explicitly listed or inherent to such processes, methods, products, or devices.

[0030] This application provides a YSZ thermal barrier coating with a controllable non-penetrating porous structure and its preparation method. The YSZ thermal barrier coating is obtained by spraying YSZ ceramic composite powder onto the surface of an adhesive layer on a substrate using a spraying technique. A schematic diagram of the microstructure of the non-penetrating porous YSZ thermal barrier coating prepared in this application is shown below. Figure 1 As shown.

[0031] in Figure 1 This is a schematic diagram of the coating's microstructure, depicting the "non-penetrating" nature of the pores (i.e., the pores are isolated and not interconnected). This structure is formed through the synergistic effect of three powders: hollow spherical powder forms isolated pores, while nano- and micron-sized powders form a dense matrix surrounding the pores, preventing them from connecting. Furthermore, in the schematic diagram, the pores should appear as closed, discontinuous pores, rather than a network or crack-like structure, thereby reducing crack propagation paths and improving the coating's mechanical strength and thermal stability.

[0032] Specifically, the YSZ ceramic composite powder consists of nanocrystalline YSZ powder with a particle size of 35μm–65μm, micron-sized YSZ powder with a particle size of 35μm–65μm, and hollow spherical YSZ powder with a particle size of 39μm–69μm. The hollow spherical YSZ powder is prepared using an aeration-melting-crushing-spheroidizing process, exhibiting a high hollow volume ratio and high density in the non-hollow portions.

[0033] Specifically, Figure 2 Microscopic morphology (SEM) of hollow spherical YSZ ceramic powder; Figure 3 Microscopic morphology (SEM) of micron-sized YSZ ceramic powder; Figure 4 Microscopic morphology (SEM) of nanocrystalline aggregated YSZ ceramic powder.

[0034] Hollow spherical YSZ powder is obtained by plasma spheroidization of agglomerated YSZ powder. The agglomerated YSZ powder is treated with plasma spheroidization at a power of 30-40 kW and a powder feeding rate of 2-4 kg / h. After natural cooling, the powder is sieved to obtain hollow spherical YSZ powder with a particle size of 39 μm-69 μm. Example Example

[0035] This application provides a method for preparing a YSZ thermal barrier coating with a controllable non-penetrating pore structure, the specific steps of which are as follows: S1. Powder Mixing Step: 20% by mass of nanocrystalline agglomerated YSZ powder, 20% by mass of micron-sized YSZ powder, and 60% by mass of hollow spherical YSZ powder were homogenized and then uniformly mixed using a planetary ball mill at a ball-to-powder ratio of 8:1, a milling speed of 260 r / min, and a milling time of 4 h. The powder was then placed in a vacuum drying oven and dried at 80℃ for 2 h to obtain YSZ ceramic composite powder.

[0036] S2. Adhesive layer preparation steps: The surface of the Inconel 718 high-temperature alloy substrate is cleaned by ultrasonic cleaning, rinsed with anhydrous ethanol for 10 to 15 minutes, and then sandblasted to make the surface roughness Ra ≥ 4μm.

[0037] Then, a NiCoCrAlY bonding layer was prepared on the substrate surface using plasma thermal spraying technology. The plasma spraying parameters included: power of 40 kW, argon as the powder feeding gas, main gas flow rate of 35 SLPM, powder feeding rate of 30 g / min, spraying distance of 110 mm, compressed air cooling during the spraying process, and the bonding layer thickness of 150 μm. The bonding layer surface was then cleaned with anhydrous ethanol.

[0038] S3. Ceramic layer preparation steps: A YSZ thermal barrier coating with a controllable non-penetrating pore structure was prepared on the surface of the adhesive layer using plasma thermal spraying technology, and the preparation method thereof was also described. The plasma thermal spraying parameters were: power 42 kW, powder feeding gas Ar, main gas flow rate 30-40 SLPM, powder feeding speed 45 g / min, spraying distance 150 mm, and compressed air was used to blow the coating surface to cool the coating; a thermal barrier coating with a ceramic layer thickness of 200 μm was obtained.

[0039] The microstructure of the YSZ thermal barrier coating with controllable non-penetrating porosity prepared in Example 1 was characterized. Specifically, Figure 5 The surface microstructure (SEM) of the obtained YSZ thermal barrier coating with controllable non-penetrating porosity is shown. Figure 6The microstructure (SEM) of the cross-section of the obtained YSZ thermal barrier coating with controllable non-penetrating porosity is shown.

[0040] The thermal barrier coating prepared in Example 1 was tested using SEM, Vickers hardness, tensile adhesion, and laser thermal conductivity. The coating exhibited good melting effect, dense internal structure, almost no microcracks, porosity of approximately 9%-12%, hardness of approximately 410HV0.2-450HV0.2, bonding strength ≥53MPa, and thermal conductivity of the substrate of approximately 20.23-22.14 (W / (m*k)). After removal, the thermal conductivity of the ceramic layer alone was approximately 0.75-1.21 (W / (m*k)), meeting the performance requirements. Example

[0041] The difference between Example 2 and Example 1 lies in the mixing ratio of nanocrystalline agglomerated YSZ powder, micron-sized YSZ powder, and hollow spherical YSZ powder in the powder mixing step; and the different plasma thermal spraying parameters in the ceramic layer preparation step. The specific steps of Example 2 are as follows: S1. Powder Mixing Step: 30% by mass of nanocrystalline agglomerated YSZ powder, 20% by mass of micron-sized YSZ powder, and 50% by mass of hollow spherical YSZ powder were homogenized and then uniformly mixed using a planetary ball mill at a ball-to-powder ratio of 8:1, a milling speed of 260 r / min, and a milling time of 4 h. The powder was then placed in a vacuum drying oven and dried at 80℃ for 2 h to obtain YSZ ceramic composite powder.

[0042] S2. Adhesive layer preparation steps: The surface of the Inconel 718 high-temperature alloy substrate is cleaned by ultrasonic cleaning, rinsed with anhydrous ethanol for 10 to 15 minutes, and then sandblasted to make the surface roughness Ra ≥ 4μm.

[0043] Then, a NiCoCrAlY bonding layer was prepared on the substrate surface using plasma thermal spraying technology. The plasma spraying parameters included: power of 40 kW, argon as the powder feeding gas, main gas flow rate of 35 SLPM, powder feeding rate of 30 g / min, spraying distance of 110 mm, compressed air cooling during the spraying process, and the bonding layer thickness of 150 μm. The bonding layer surface was then cleaned with anhydrous ethanol.

[0044] S3. Ceramic layer preparation steps: A YSZ thermal barrier coating with a controllable non-penetrating pore structure was prepared on the surface of the adhesive layer using plasma thermal spraying technology, and the preparation method thereof was also described. The plasma thermal spraying parameters were: power 50 kW, powder feeding gas Ar, main gas flow rate 30-40 SLPM, powder feeding speed 40 g / min, spraying distance 150 mm, and compressed air was used to blow the coating surface to cool the coating; a thermal barrier coating with a ceramic layer thickness of 200 μm was obtained.

[0045] The thermal barrier coating prepared by the method in Example 2 was tested by SEM, Vickers hardness, tensile adhesion, and laser thermal conductivity. The coating showed good melting effect, dense interior, almost no microcracks, porosity of about 7%-10%, hardness of about 430HV0.2-470HV0.2, bonding strength ≥53MPa, thermal conductivity of the substrate of about 20.68-22.77 (W / (m*k)), and thermal conductivity of the ceramic layer after removal of the substrate of about 0.79-1.27 (W / (m*k)), which meets the performance requirements. Example

[0046] The difference between Example 3 and Example 1 lies in the different mixing ratios of nanocrystalline agglomerated YSZ powder, micron-sized YSZ powder, and hollow spherical YSZ powder in the powder mixing step; and the different plasma thermal spraying parameters in the ceramic layer preparation step. The specific steps of Example 3 are as follows: S1. Powder Mixing Step: 30% by mass of nanocrystalline agglomerated YSZ powder, 30% by mass of micron-sized YSZ powder, and 40% by mass of hollow spherical YSZ powder were homogenized and then uniformly mixed using a planetary ball mill at a ball-to-powder ratio of 8:1, a milling speed of 260 r / min, and a milling time of 4 h. The powder was then placed in a vacuum drying oven and dried at 80℃ for 2 h to obtain YSZ ceramic composite powder.

[0047] S2. Adhesive layer preparation steps: The surface of the Inconel 718 high-temperature alloy substrate is cleaned by ultrasonic cleaning, rinsed with anhydrous ethanol for 10 to 15 minutes, and then sandblasted to make the surface roughness Ra ≥ 4μm.

[0048] Then, a NiCoCrAlY bonding layer was prepared on the substrate surface using plasma thermal spraying technology. The plasma spraying parameters included: power of 40 kW, argon as the powder feeding gas, main gas flow rate of 35 SLPM, powder feeding rate of 30 g / min, spraying distance of 110 mm, compressed air cooling during the spraying process, and the bonding layer thickness of 150 μm. The bonding layer surface was then cleaned with anhydrous ethanol.

[0049] S3. Ceramic layer preparation steps: A YSZ thermal barrier coating with a controllable non-penetrating pore structure was prepared on the surface of the adhesive layer using plasma thermal spraying technology, and the preparation method thereof was also described. The plasma thermal spraying parameters were: power 58 kW, powder feeding gas Ar, main gas flow rate 30-40 SLPM, powder feeding speed 35 g / min, spraying distance 150 mm, and compressed air was used to blow the coating surface to cool the coating; a thermal barrier coating with a ceramic layer thickness of 200 μm was obtained.

[0050] The thermal barrier coating prepared by the method in Example 3 was tested by SEM, Vickers hardness, and laser thermal conductivity meter. The coating showed good melting effect, dense interior with almost no microcracks, porosity of about 6%-9%, hardness of about 460HV0.2-500HV0.2, bonding strength ≥53MPa, thermal conductivity of the substrate of about 20.89-22.92 (W / (m*k)), and thermal conductivity of the ceramic layer after removal of the substrate of about 0.81-1.33 (W / (m*k)), which meets the performance requirements.

[0051] Examples 1, 2, and 3 all describe the preparation method of the YSZ thermal barrier coating, but differences in powder ratio and some process parameters lead to variations in coating performance. Specifically, in Examples 1 to 3, the proportion of hollow spherical YSZ powder gradually decreased from 60% to 40%, while the proportion of nano and micron powders increased accordingly. This change aims to adjust the pore structure and density of the coating: a higher proportion of hollow powder introduces more pores but may reduce mechanical strength; an increased proportion of nano and micron powders enhances the density and hardness of the coating. However, all examples exhibited internal density with almost no microcracks and high bonding strength, verifying the effectiveness of the non-penetrating pore structure.

[0052] Comparative Example Comparative Example 1 This application provides a method for preparing a single-powder YSZ thermal barrier coating, the specific steps of which are as follows: S1. Powder Preparation Steps: This comparative example uses single-component hollow spherical YSZ powder (100% composition, particle size 39-69 μm). To maintain the original morphological characteristics of the hollow spherical powder, planetary ball milling is not performed. The powder is simply placed in a vacuum drying oven and dried at 80°C for 2 hours to remove moisture, and then used directly for spraying.

[0053] S2. Adhesive layer preparation steps: The surface of the Inconel 718 high-temperature alloy substrate is cleaned by ultrasonic cleaning, rinsed with anhydrous ethanol for 10 to 15 minutes, and then sandblasted to make the surface roughness Ra ≥ 4μm.

[0054] Then, a NiCoCrAlY bonding layer was prepared on the substrate surface using plasma thermal spraying technology. The plasma spraying parameters included: power of 40 kW, argon as the powder feeding gas, main gas flow rate of 35 SLPM, powder feeding rate of 30 g / min, spraying distance of 110 mm, compressed air cooling during the spraying process, and the bonding layer thickness of 150 μm. The bonding layer surface was then cleaned with anhydrous ethanol.

[0055] S3. Ceramic layer preparation steps: The plasma thermal spraying parameters are: power 42 kW, powder feeding gas is Ar, main gas flow rate 30-40 SLPM, powder feeding speed 45 g / min, spraying distance 150 mm, and compressed air is used to blow the coating surface to cool the coating; a thermal barrier coating with a ceramic layer thickness of 200 μm is obtained.

[0056] The thermal barrier coating prepared by the method in Comparative Example 1 was tested by SEM, Vickers hardness, tensile test and laser thermal conductivity meter. The coating has good melting effect and few microcracks, but there are some interconnected large-sized pores. The porosity is about 15%-20%, the hardness is about 330HV0.2-380HV0.2, the bonding strength is ≥45Mpa, the thermal conductivity of the substrate is about 23.01-24.22 (W / (m*k)) and the thermal conductivity of the ceramic layer is about 1.03-1.27 (W / (m*k)).

[0057] The above data shows that, due to the lack of filling and bridging by nanocrystals and micron particles, single hollow sphere powder coatings cannot form a microstructure with isolated and unconnected pores. The decrease in mechanical strength (hardness) indicates that the non-penetrating porous structure with both low thermal conductivity and high mechanical strength prepared by the present invention cannot be achieved by relying solely on powders with a single morphology.

[0058] Comparative Example 2 This application provides a method for preparing a single-powder YSZ thermal barrier coating, the specific steps of which are as follows: S1. Powder Preparation Steps: This comparative example uses a single-component nanocrystalline agglomerate YSZ powder (100% concentration, particle size 35-65 μm). To maintain the original morphology of the nanocrystalline agglomerate powder, planetary ball milling is not performed. The powder is simply placed in a vacuum drying oven and dried at 80°C for 2 hours to remove moisture, and then used directly for spraying.

[0059] S2. Adhesive layer preparation steps: The surface of the Inconel 718 high-temperature alloy substrate is cleaned by ultrasonic cleaning, rinsed with anhydrous ethanol for 10 to 15 minutes, and then sandblasted to make the surface roughness Ra ≥ 4μm.

[0060] Then, a NiCoCrAlY bonding layer was prepared on the substrate surface using plasma thermal spraying technology. The plasma spraying parameters included: power of 40 kW, argon as the powder feeding gas, main gas flow rate of 35 SLPM, powder feeding rate of 30 g / min, spraying distance of 110 mm, compressed air cooling during the spraying process, and the bonding layer thickness of 150 μm. The bonding layer surface was then cleaned with anhydrous ethanol.

[0061] S3. Ceramic layer preparation steps: The plasma thermal spraying parameters are: power 42 kW, powder feeding gas is Ar, main gas flow rate 30-40 SLPM, powder feeding speed 45 g / min, spraying distance 150 mm, and compressed air is used to blow the coating surface to cool the coating; a thermal barrier coating with a ceramic layer thickness of 200 μm is obtained.

[0062] The thermal barrier coating prepared by the method in Comparative Example 2 was tested by SEM, Vickers hardness, tensile test and laser thermal conductivity meter. The coating has good melting effect, a small amount of unmelted particles, large interlayer gap, microcracks of about 2%-7%, porosity of about 10%-20%, hardness of about 310HV0.2-360HV0.2, bonding strength ≥36MPa, thermal conductivity of the substrate of about 22.21-23.33 (W / (m*k)) and thermal conductivity of the ceramic layer of about 0.85-1.43 (W / (m*k)).

[0063] The above data shows that although the single nanocrystalline agglomerate powder coating has excellent thermal insulation ability, the presence of some unmelted particles and large interlayer gaps lead to uneven hardness distribution and low bonding strength. This indicates that the non-penetrating porous structure with both low thermal conductivity and high mechanical strength prepared by the present invention cannot be achieved by relying solely on powders with a single morphology.

[0064] It should be noted that the order of the embodiments described above is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. Furthermore, specific embodiments have been described above. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps described in the claims can be performed in a different order than that shown in the embodiments and still achieve the desired result. Additionally, the processes depicted in the drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0065] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

[0066] This specification and accompanying drawings are merely illustrative examples of this application and are intended to cover any and all modifications, variations, combinations, or equivalents within the scope of this application. Clearly, those skilled in the art can make various alterations and modifications to this application without departing from its scope. Therefore, if such modifications and modifications fall within the scope of this application and its equivalents, this application intends to include such modifications and modifications.

Claims

1. A YSZ thermal barrier coating with a controllable non-penetrating pore structure, characterized in that, The YSZ thermal barrier coating is formed by plasma spraying of YSZ ceramic composite powder, and the YSZ ceramic composite powder comprises the following components mixed in mass percentage: Nanocrystalline aggregated YSZ powder, accounting for 20%–30%; Micron-sized YSZ powder, accounting for 20%–30%; Hollow spherical YSZ powder, accounting for 40%–60%; The coating has a porosity of 6%-12%, and the pore structure is non-penetrating, with pores distributed in isolation and not connected.

2. The YSZ thermal barrier coating with a controllable non-penetrating pore structure as described in claim 1, characterized in that, The particle size range of the nanocrystalline aggregated YSZ powder is 35μm–65μm, the particle size range of the micron-sized YSZ powder is 35μm–65μm, and the particle size range of the hollow spherical YSZ powder is 39μm–69μm. The hollow spherical YSZ powder is prepared by an aeration-melting and crushing-spheroidizing process. The hollow volume ratio of the hollow spherical YSZ powder is uniform and controllable: 50%-70%, and the density of the non-hollow part is 99.5%-99.9%.

3. A method for preparing a YSZ thermal barrier coating with a controllable non-penetrating pore structure as described in any one of claims 1 or 2, characterized in that, The following steps are included: S1. Powder mixing step: Mix nanocrystalline aggregated YSZ powder, micron-sized YSZ powder and hollow spherical YSZ powder in a certain proportion, perform homogenization treatment, and then dry in a vacuum drying oven to obtain YSZ ceramic composite powder. S2. Adhesive layer preparation steps: A high-temperature alloy is selected as the substrate, and it is ultrasonically cleaned. Then, the substrate surface is sandblasted. A NiCoCrAlY adhesive layer is prepared on the substrate surface using plasma spraying technology, and then the adhesive layer surface is cleaned. S3. Ceramic layer preparation steps: The YSZ ceramic composite powder is sprayed onto the surface of the NiCoCrAlY bonding layer using plasma spraying technology. During the spraying process, compressed air is used to blow away the coating surface and control the thickness of the ceramic layer.

4. The method for preparing a YSZ thermal barrier coating with a controllable non-penetrating pore structure as described in claim 3, characterized in that, In step S1, The nanocrystalline aggregated YSZ powder, the micron-sized YSZ powder, and the hollow spherical YSZ powder were mixed in a certain proportion and homogenized using a planetary ball mill with a ball-to-material ratio of 8:1, a ball milling speed of 260 r / min, and a ball milling time of 4 h. The mixed powder was dried in a vacuum drying oven at a temperature of 80℃–100℃ for 2 h–4 h.

5. The method for preparing a YSZ thermal barrier coating with a controllable non-penetrating pore structure as described in claim 3, characterized in that, In step S2, Inconel 718 high-temperature alloy was selected as the substrate and ultrasonically cleaned with anhydrous ethanol for 10–15 minutes. Then, the substrate surface was sandblasted.

6. The method for preparing a YSZ thermal barrier coating with a controllable non-penetrating pore structure as described in claim 5, characterized in that, In step S2, A NiCoCrAlY bonding layer was prepared on the substrate surface using plasma spraying technology. The plasma spraying parameters included: power 30kW–50kW, argon as the powder feed gas, main gas flow rate 30 SLPM–40 SLPM, powder feed rate 20 g / min–40 g / min, spraying distance 100 mm–120 mm, compressed air cooling during the spraying process, and the bonding layer thickness was controlled to be 100 μm–200 μm. The bonding layer surface was then cleaned.

7. The method for preparing a YSZ thermal barrier coating with a controllable non-penetrating pore structure as described in claim 3, characterized in that, In step S3, The YSZ ceramic composite powder was sprayed onto the surface of the NiCoCrAlY binder using plasma spraying technology. The plasma spraying parameters included: power 40 kW–60 kW, argon as the powder feed gas, main gas flow rate 30 SLPM–40 SLPM, powder feed rate 30 g / min–50 g / min, spraying distance 150 mm–200 mm, and spray gun moving speed 10 mm / s–30 mm / s. During the spraying process, compressed air was used to blow away the coating surface to cool the coating. The thickness of the ceramic layer was controlled to be 150 μm–300 μm, thus obtaining a YSZ thermal barrier coating with a controllable non-penetrating pore structure.

8. The method for preparing a YSZ thermal barrier coating with a controllable non-penetrating pore structure as described in claim 3, characterized in that, In step S1, The hollow spherical YSZ powder is obtained by plasma spheroidization treatment of ordinary agglomerated YSZ powder.

9. The method for preparing a YSZ thermal barrier coating with a controllable non-penetrating pore structure as described in claim 8, characterized in that, The hollow spherical YSZ powder is agglomerated by plasma spheroidization. The plasma spheroidization process has a power of 30-40kW and a powder feeding rate of 2-4kg / h. After natural cooling, it is sieved to obtain hollow spherical YSZ powder with a particle size of 39μm-69μm.

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