Preparation method of non-vertical-crack environmental barrier coating based on suspension plasma spraying

Abstract

The invention relates to the technical field of high-temperature protective coatings, and discloses a preparation method of a vertical-crack-free environmental barrier coating based on suspension plasma spraying. The method comprises the following steps: respectively constructing an environmental barrier coating quenching stress analysis model, a thermal mismatch stress analysis model and a thermal gradient stress analysis model based on a deposition temperature in the process of coating the environmental barrier coating by adopting suspension plasma spraying on a base material; and determining an objective function of the stress level of the environmental barrier coating according to the sum of the output values of the three analysis models, and optimizing the objective function to obtain an optimal control value of the deposition temperature in the plasma spraying process so as to reduce the stress level in the environmental barrier coating. According to the method, vertical cracks can be prevented from being generated in the environmental barrier coating, and the performance of the environmental barrier coating is improved.

Description

Technical Field

[0001] This invention relates to the field of high-temperature protective coating technology, and discloses a method for preparing a vertical crack-free environmental barrier coating based on suspension plasma spraying. Background Technology

[0002] SiC f / SiC m Ceramic matrix composites (CMCs) have become a promising candidate material for next-generation high-temperature structural materials in aero-engines due to their lightweight, excellent high-temperature mechanical properties, and high-temperature oxidation resistance. Currently, CMCs exhibit good high-temperature oxidation resistance under dry air because the surface oxidation forms a dense SiO2 oxide film that protects the substrate from further oxidation. The long-term operating temperature of CMCs can reach 1300℃. However, the aero-engine exhaust environment contains a large amount of water vapor, causing rapid corrosion and degradation of CMCs in high-temperature, water-oxygen environments, with degradation rates reaching tens of micrometers per hour.

[0003] Current solutions involve coating CMC materials with a dense environmental barrier coating that isolates them from water and oxygen. These environmental barrier coatings primarily utilize rare-earth silicate materials such as Yb₂Si₂O₇, Yb₂SiO₅, and Y₂SiO₅. The most common method for preparing these coatings is plasma spraying, which includes atmospheric plasma spraying, suspension plasma spraying, vacuum plasma spraying, and plasma-based physical vapor deposition. Plasma spraying uses a plasma flame as a heat source to heat and melt ceramic powder to a molten or semi-molten state. The powder is then accelerated and impacted onto the substrate surface, where it cools, solidifies, and stacks to form the coating.

[0004] like Figure 1 As shown, existing environmental barrier coatings are prone to vertical cracks during preparation. These cracks compromise coating integrity and become rapid channels for the intrusion of high-temperature water and oxygen fuel gases. The intruding high-temperature water and oxygen gases quickly contact the substrate, causing rapid corrosion and degradation, and generating volatile substances that lead to coating peeling. The exposed CMC substrate then undergoes rapid corrosion and degradation in the fuel gas environment, resulting in rapid CMC substrate failure. High-performance environmental barrier coatings must have a dense structure free of vertical cracks to effectively resist water vapor intrusion. Therefore, to extend the service life and reliability of the CMC substrate, an environmental barrier coating that isolates water vapor must be prepared on the CMC substrate surface. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a crack-free environmental barrier coating based on suspension plasma spraying, which can reduce the stress level in the environmental barrier coating, thereby avoiding the generation of vertical cracks in the environmental barrier coating and improving the performance of the environmental barrier coating.

[0006] To achieve the above-mentioned technical effects, the technical solution adopted by the present invention is as follows: A method for preparing a vertical crack-free environmental barrier coating based on suspension plasma spraying includes: Based on the performance parameters of the environmental barrier coating powder material and the deposition temperature of the environmental barrier coating under plasma spraying conditions, a quenching stress analysis model for the environmental barrier coating based on the deposition temperature is constructed. Based on the performance parameters of the environmental barrier coating structure and the material performance parameters of the substrate to which the environmental barrier coating structure is coated, a thermal mismatch stress analysis model for the environmental barrier coating based on the deposition temperature is constructed. Based on the performance parameters of the environmental barrier coating structure, the material performance parameters of the substrate to which the environmental barrier coating structure is coated, and the temperature gradient change value between the surface temperature and the internal temperature of the substrate material caused by the corresponding deposition temperature during the deposition process, a thermal gradient stress analysis model for the environmental barrier coating based on the deposition temperature is constructed. Using deposition temperature as the design variable, the optimization objective is to minimize the sum of the output values ​​of the quenching stress analysis model, the thermal mismatch stress analysis model, and the thermal gradient stress analysis model. The optimal control value of deposition temperature is then obtained through analysis. The environmental barrier coating powder material is uniformly mixed with an organic solvent to form a suspension. The suspension is used as the spraying raw material for the environmental barrier coating structure. The substrate is plasma sprayed with a plasma spray gun to a preset coating thickness to complete the preparation of the environmental barrier coating. During the plasma spraying process, the deposition temperature of the environmental barrier coating is controlled by adjusting the oscillation speed and amplitude of the plasma spray gun, so that the absolute deviation between the deposition temperature and the optimal control value is not greater than a preset deviation threshold.

[0007] Furthermore, the constructed environmental barrier coating quenching stress analysis model based on deposition temperature is as follows: ,in The deposition temperature during plasma spraying is The quenching stress of the environmental barrier coating structure Poisson's ratio for environmental barrier coating powder materials The elastic modulus of the environmental barrier coating powder material. The coefficient of thermal expansion of the environmental barrier coating powder material, Melting point of environmental barrier coating powder materials.

[0008] Furthermore, the constructed environmental barrier coating thermal mismatch stress analysis model based on deposition temperature is as follows: ,in The deposition temperature during plasma spraying is Thermal mismatch stress in the environmental barrier coating structure The Poisson's ratio of the post-deposition environmental barrier coating structure. The elastic modulus of the environmental barrier coating structure, The coefficient of thermal expansion of the environmental barrier coating powder material, The coefficient of thermal expansion of the matrix material is given. The deposition environment temperature during plasma spraying.

[0009] Furthermore, the constructed environmental barrier coating thermal gradient stress analysis model based on deposition temperature is as follows: ,in The surface temperature of the coating after plasma spraying is reduced from Cool to The thermal gradient stress generated in the coating during the process To achieve the deposition temperature on the substrate surface during spraying, the corresponding internal temperature of the substrate is: , It is the surface deposition temperature at which the temperature gradient changes the most. It is the internal temperature of the coating substrate when the temperature gradient changes the most. The Poisson's ratio of the post-deposition environmental barrier coating structure. The elastic modulus of the environmental barrier coating structure, The coefficient of thermal expansion of the environmental barrier coating structure.

[0010] Furthermore, the environmental barrier coating powder material includes one or more combinations of Yb2Si2O7, YYbSi2O7, Yb2SiO5, Y2SiO5, La2Hf2O7, Gd2Si2O7, mullite, and BSAS ceramic powder.

[0011] Furthermore, the suspension solvent uses a flammable organic solvent, including one or more combinations of alcohol, gasoline, acetone, and diethyl ether.

[0012] Furthermore, the average particle size of the environmental barrier coating powder material is less than or equal to 2 μm, and the solid content in the formed suspension is 5% to 40%.

[0013] Furthermore, the method of using the suspension as the spraying material for the environmental barrier coating structure and employing a plasma spray gun to perform plasma spraying on the coating substrate to a preset coating thickness includes: The matrix material is preheated by turning on the plasma spray gun without any suspension input; the matrix material is a SiC ceramic matrix composite material, and the preheating temperature does not exceed 800°C. After preheating, ensure the plasma spray gun continuously heats the substrate material, using nitrogen at 50-300 slpm, argon at 20-100 slpm, and helium at 15-60 slpm as the plasma working gas. Simultaneously, activate the suspension injection of the plasma spray gun to spray the environmental barrier coating. The deposition temperature is controlled at 1000℃-1300℃, and the suspension injection rate is 10-150 ml / min. By controlling the injection rate of the suspension, the porosity of the environmental barrier coating is controlled within the range of 5%-30%. After spraying, stop injecting the suspension and use the plasma flame of the suspension plasma spray gun to continuously heat the environmental barrier coating. Reduce the surface temperature of the coating sample to 800℃ within a preset time. After keeping the coating sample at this temperature for 3-10 minutes, turn off the spray gun and allow the coating sample to cool naturally to room temperature. This completes the preparation of the environmental barrier coating and yields an environmental barrier coating without vertical through cracks.

[0014] Furthermore, the number of spraying cycles is controlled to keep the thickness of the environmental barrier coating within the range of 50-300 μm.

[0015] Compared with the prior art, the beneficial effects of this invention are as follows: This invention constructs three analysis models based on deposition temperature during the deposition of an environmental barrier coating using plasma spraying: an environmental barrier coating quenching stress analysis model, a thermal mismatch stress analysis model, and a thermal gradient stress analysis model. The sum of the output values ​​of the three analysis models determines the objective function for the stress level of the environmental barrier coating. By optimizing the objective function, the optimal control value of the deposition temperature during the plasma spraying process is obtained, thereby reducing the stress level in the environmental barrier coating, thus avoiding the generation of vertical cracks in the environmental barrier coating and improving the performance of the environmental barrier coating. Attached Figure Description

[0016] Figure 1 Microstructure diagram of existing environmental barrier coating cross section; Figure 2 This is a flowchart of the method for preparing a vertical crack-free environmental barrier coating based on suspension plasma spraying in Example 1 or 2. Figure 3 This is a microstructure diagram of the Si adhesive layer in Example 2; Figure 4 This is a microstructure diagram of the environmental barrier coating without vertical cracks prepared in Example 2. Detailed Implementation

[0017] The present invention will now be described in further detail with reference to the embodiments and accompanying drawings. However, this should not be construed as limiting the scope of the above-described subject matter of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0018] Example 1 See Figures 1 to 2 A method for preparing a vertical crack-free environmental barrier coating based on suspension plasma spraying includes: Based on the performance parameters of the environmental barrier coating powder material and the deposition temperature of the environmental barrier coating under plasma spraying conditions, a quenching stress analysis model for the environmental barrier coating based on the deposition temperature is constructed. Based on the performance parameters of the environmental barrier coating structure and the material performance parameters of the substrate to which the environmental barrier coating structure is coated, a thermal mismatch stress analysis model for the environmental barrier coating based on the deposition temperature is constructed. Based on the performance parameters of the environmental barrier coating structure, the material performance parameters of the substrate to which the environmental barrier coating structure is coated, and the temperature gradient change value between the surface temperature and the internal temperature of the substrate material caused by the corresponding deposition temperature during the deposition process, a thermal gradient stress analysis model for the environmental barrier coating based on the deposition temperature is constructed. Using deposition temperature as the design variable, the optimization objective is to minimize the sum of the output values ​​of the quenching stress analysis model, the thermal mismatch stress analysis model, and the thermal gradient stress analysis model. The optimal control value of deposition temperature is then obtained through analysis. The environmental barrier coating powder material is uniformly mixed with an organic solvent to form a suspension. The suspension is used as the spraying raw material for the environmental barrier coating structure. The substrate is plasma sprayed with a plasma spray gun to a preset coating thickness to complete the preparation of the environmental barrier coating. During the plasma spraying process, the deposition temperature of the environmental barrier coating is controlled by adjusting the oscillation speed and amplitude of the plasma spray gun, so that the absolute deviation between the deposition temperature and the optimal control value is not greater than a preset deviation threshold.

[0019] In this embodiment, three stress analysis models based on deposition temperature are constructed for the environmental barrier coating process using plasma spraying on the substrate material: a quenching stress analysis model, a thermal mismatch stress analysis model, and a thermal gradient stress analysis model. The sum of the output values ​​of the three analysis models determines the objective function for the stress level of the environmental barrier coating. By optimizing the objective function, the optimal control value of the deposition temperature during the plasma spraying process is obtained to reduce the stress level in the environmental barrier coating. In addition, the spraying parameters, such as spray gun power, spraying distance, and spray gun swing amplitude, can be optimized to match the spraying parameters with the optimal deposition temperature during the spraying process, ultimately avoiding vertical cracks in the environmental barrier coating and improving its performance.

[0020] Example 2 See Figures 2-4 In this embodiment, Yb2Si2O7 is used as the environmental barrier coating powder material, on a SiC / SiC ceramic matrix composite substrate (30*30*3mm). 3Taking the preparation of a Yb2Si2O7 environmental barrier coating as an example, the preparation process of the vertical crack-free environmental barrier coating based on suspension plasma spraying of the present invention is described in detail. The insulator operation process is as follows: Step 1: Based on the performance parameters of the environmental barrier coating powder material and the deposition temperature of the environmental barrier coating under plasma spraying conditions, construct a quenching stress analysis model for the environmental barrier coating based on the deposition temperature. In this embodiment, the constructed environmental barrier coating quenching stress analysis model based on deposition temperature is as follows: ,in The deposition temperature during plasma spraying is The quenching stress of the environmental barrier coating structure Poisson's ratio for environmental barrier coating powder materials The elastic modulus of the environmental barrier coating powder material. The coefficient of thermal expansion of the environmental barrier coating powder material, Melting point of environmental barrier coating powder materials.

[0021] Step 2: Based on the performance parameters of the environmental barrier coating structure and the material performance parameters of the substrate to which the environmental barrier coating structure is coated, construct a thermal mismatch stress analysis model for the environmental barrier coating based on the deposition temperature. In this embodiment, the constructed environmental barrier coating thermal mismatch stress analysis model based on deposition temperature is as follows: ,in The deposition temperature during plasma spraying is Thermal mismatch stress in the environmental barrier coating structure The Poisson's ratio of the post-deposition environmental barrier coating structure. The elastic modulus of the environmental barrier coating structure, The coefficient of thermal expansion of the environmental barrier coating powder material, The coefficient of thermal expansion of the matrix material is given. The deposition environment temperature during plasma spraying can be obtained by monitoring the deposition temperature on the sample surface using an infrared thermometer.

[0022] Step 3: Based on the performance parameters of the environmental barrier coating structure, the material performance parameters of the substrate to which the environmental barrier coating structure is coated, and the temperature gradient change value between the surface temperature and the internal temperature of the substrate material caused by the corresponding deposition temperature during the deposition process, construct a thermal gradient stress analysis model for the environmental barrier coating based on the deposition temperature. In this embodiment, the constructed environmental barrier coating thermal gradient stress analysis model based on deposition temperature is as follows: ,in The surface temperature of the coating after plasma spraying is reduced from Cool to The thermal gradient stress generated in the coating during the process To achieve the deposition temperature on the substrate surface during spraying, the corresponding internal temperature of the substrate is: , It is the surface deposition temperature at which the temperature gradient changes the most. It is the internal temperature of the coating substrate when the temperature gradient changes the most. The Poisson's ratio of the post-deposition environmental barrier coating structure. The elastic modulus of the environmental barrier coating structure, The coefficient of thermal expansion of the environmental barrier coating structure; , The data was obtained through monitoring using a thermocouple pre-embedded at the center of the matrix material.

[0023] Step 4: Using deposition temperature as the design variable, the optimization objective is to minimize the sum of the output values ​​of the quenching stress analysis model, the thermal mismatch stress analysis model, and the thermal gradient stress analysis model. The optimal control value of deposition temperature is then obtained through analysis. Step 5: Mix the environmental barrier coating powder material with an organic solvent to form a suspension. Use the suspension as the spraying material for the environmental barrier coating structure. Use a plasma spray gun to perform plasma spraying on the coating substrate to the preset coating thickness to complete the preparation of the environmental barrier coating. During the plasma spraying process, the deposition temperature of the environmental barrier coating is controlled by adjusting the oscillation speed and amplitude of the plasma spray gun, so that the absolute deviation between the deposition temperature and the optimal control value is not greater than the preset deviation threshold.

[0024] 5.1 Place approximately 300g of Yb2Si2O7 powder (average diameter 60 micrometers, purity above 99.5%), 900g of ZrO2 ceramic grinding balls with a diameter of 3mm, and 4.5g of organic dispersant (PEI) into a wide-mouth plastic bottle, and pour 700g of 99.9% pure alcohol into the plastic bottle and shake well.

[0025] 5.2 Seal the wide-mouth plastic bottle with plastic tape. Place the sealed plastic bottle flat on a axial roller mill. Set the roller mill speed to 30-60 r / min, and adjust the grinding time within the range of 1-7 days. During the grinding process, take a portion of the suspension for particle size analysis. Stop grinding when the average particle size of the ceramic powder is <2μm. After stopping grinding, the solid content of the suspension can be reduced to 5%-40% by adding alcohol.

[0026] 5.3 Place the SiC / SiC ceramic matrix composite substrate (30*30*3mm) to be sprayed. 3The substrate was ultrasonically cleaned in an alcohol solution for 5 minutes at room temperature and an ultrasonic frequency of 20 kHz. After cleaning, the substrate was dried by blowing with compressed air at a pressure of 6-8 bar. The ceramic matrix composite substrate was then held in a clamp with the surface to be coated facing the spray gun. The spray gun used was the TriplexPro model from Oerlikon, employing a matrix scanning mode with a scanning step of 2 mm, a spraying distance of 200 mm, a spraying current of 420 A, a voltage of 90 V, and a spray gun power of 37.6 kW. The plasma gas used was Ar (46 SLPM) and He (4 SLPM), and the coating powder was Metco from Oerlikon. The 4810 type Si powder (purity >99.0%) had an average particle diameter of 53 ± 15 μm and a feed rate of 2 g / min. Before spraying, the sample surface temperature was heated to 200°C using a plasma spray gun. During spraying, the sample surface temperature was controlled to not exceed 270°C. After three spraying cycles, a uniform Si binder layer with a thickness of 150 μm was obtained. Figure 3 As shown, the surface roughness of the adhesive layer is 5 ± 2 micrometers.

[0027] 5.4 Place the substrate (30*30*3mm) with the Si adhesive layer to be coated. 3 Ultrasonic cleaning was performed in an alcohol solution at room temperature, with an ultrasonic frequency of 20-40 kHz and a cleaning time of 5 minutes. After cleaning, the sample was dried with compressed air and clamped on a turntable. The surface to be sprayed was perpendicular to the spraying direction of the spray gun. In addition, an infrared thermometer was set up 1.5 m away from the sample to monitor the deposition temperature of the coating surface. The substrate material was preheated by turning on the plasma spray gun without any suspension input. The substrate material was a SiC ceramic matrix composite material, and the preheating temperature did not exceed 800℃. The plasma gas used was nitrogen (50-300 slpm), argon (20-100 slpm), and helium (15-60 slpm). The current was 220*3 A, and the arc voltage was 40V. After the plasma flame stabilized, the sample was preheated by the plasma flame.

[0028] 5.5 After preheating is complete, ensure that the plasma spray gun continuously heats the substrate material. Use nitrogen at 50-300 slpm, argon at 20-100 slpm, and helium at 15-60 slpm as the plasma working gas. Simultaneously, start the suspension injection of the plasma spray gun to spray the environmental barrier coating. The deposition temperature is controlled at 1000℃-1300℃, and the suspension injection rate is 10-150 ml / min. By controlling the injection rate of the suspension, the porosity of the environmental barrier coating is controlled within the range of 5%-30%. 5.6 After spraying, stop the injection of the suspension. Using the plasma flame of the suspension plasma spray gun, continuously heat the environmental barrier coating, and reduce the surface temperature of the coated sample to 800℃ within a preset time. Hold the coated sample at this temperature for 3-10 minutes, then turn off the spray gun and allow the coated sample to cool naturally to room temperature. This completes the preparation of the environmental barrier coating, obtaining an environmental barrier coating without vertical through-cracks. The microstructure of the obtained coating is as follows: Figure 4 As shown, the prepared coating has a uniform structure, no vertical cracks, and good adhesion to the substrate (the adhesion strength is greater than 10 MPa as tested), and there are no transverse cracks at the interface.

[0029] It should be noted that the suspension plasma spraying system in this embodiment uses the Axial3 spray gun manufactured by Mettech, Canada. The spraying system includes a spray gun, a suspension feeding device, a control system, a robotic arm, a turntable, fixtures, a spray booth, a water chiller, and a dust removal system. The suspension feeding device can stably deliver suspensions with a solid content of 5wt%-40wt%, and the delivery rate can be freely adjusted within the range of 5-150g / min, with a feeding accuracy of no less than ±1g / min. Before spraying, the suspension is poured into a suspension container, and the suspension fan blades are turned on to stir the suspension to prevent solid sedimentation. The feeding system is tested by pre-filling the suspension in plastic pipes. The environmental barrier coating powder material can also be one or more combinations of Yb₂Si₂O₇, YYbSi₂O₇, Yb₂SiO₅, Y₂SiO₅, La₂Hf₂O₇, Gd₂Si₂O₇, mullite, and BSAS ceramic powder. The suspension solvent can also be one or more combinations of alcohol, gasoline, acetone, and diethyl ether.

[0030] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a vertical crack-free environmental barrier coating based on suspension plasma spraying, characterized in that, include: Based on the intrinsic performance parameters of the environmental barrier coating material and the deposition temperature of the environmental barrier coating under plasma spraying conditions, a quenching stress analysis model for the environmental barrier coating based on the deposition temperature is constructed. Based on the performance parameters of the environmental barrier coating structure and the material performance parameters of the substrate to which the environmental barrier coating structure is coated, a thermal mismatch stress analysis model for the environmental barrier coating based on the deposition temperature is constructed. Based on the performance parameters of the environmental barrier coating structure, the material performance parameters of the substrate to which the environmental barrier coating structure is coated, and the temperature gradient change value between the surface temperature and the internal temperature of the substrate material caused by the corresponding deposition temperature during the deposition process, a thermal gradient stress analysis model for the environmental barrier coating based on the deposition temperature is constructed. Using deposition temperature as the design variable, the optimization objective is to minimize the sum of the output values ​​of the quenching stress analysis model, the thermal mismatch stress analysis model, and the thermal gradient stress analysis model. The optimal control value of deposition temperature is then obtained through analysis. The environmental barrier coating powder material is mixed evenly with an organic solvent to form a suspension. The suspension is used as the spraying material for the environmental barrier coating structure. The substrate is plasma sprayed to the preset coating thickness using a plasma spray gun to complete the preparation of the environmental barrier coating. During plasma spraying, the deposition temperature of the environmental barrier coating is controlled by adjusting the oscillation speed and amplitude of the plasma spray gun, so that the absolute deviation between the deposition temperature and the optimal control value is not greater than a preset deviation threshold.

2. The method for preparing a crack-free environmental barrier coating according to claim 1, characterized in that, The constructed environmental barrier coating quenching stress analysis model based on deposition temperature is as follows: ,in The deposition temperature during plasma spraying is The quenching stress of the environmental barrier coating structure Poisson's ratio for environmental barrier coating powder materials The elastic modulus of the environmental barrier coating powder material. The coefficient of thermal expansion of the environmental barrier coating powder material, Melting point of environmental barrier coating materials.

3. The method for preparing a crack-free environmental barrier coating according to claim 2, characterized in that, The constructed environmental barrier coating thermal mismatch stress analysis model based on deposition temperature is as follows: ,in The deposition temperature during plasma spraying is Thermal mismatch stress in the environmental barrier coating structure The Poisson's ratio of the post-deposition environmental barrier coating structure. The elastic modulus of the environmental barrier coating structure, The coefficient of thermal expansion of the environmental barrier coating powder material, The coefficient of thermal expansion of the matrix material is given. The deposition environment temperature during plasma spraying.

4. The method for preparing a crack-free environmental barrier coating according to claim 3, characterized in that, The constructed environmental barrier coating thermal gradient stress analysis model based on deposition temperature is as follows: ,in The surface temperature of the coating after plasma spraying is reduced from Cool to The thermal gradient stress generated in the coating during the process To achieve the deposition temperature on the substrate surface during spraying, the corresponding internal temperature of the substrate is: , It is the surface deposition temperature at which the temperature gradient changes the most. It is the internal temperature of the coating substrate when the temperature gradient changes the most. The Poisson's ratio of the post-deposition environmental barrier coating structure. The elastic modulus of the environmental barrier coating structure, The coefficient of thermal expansion of the environmental barrier coating structure.

5. The method for preparing a crack-free environmental barrier coating according to claim 1, characterized in that, Environmental barrier coating powder materials include, but are not limited to, one or more combinations of Yb2Si2O7, YYbSi2O7, Yb2SiO5, Y2SiO5, La2Hf2O7, Gd2Si2O7, mullite, and BSAS ceramic powder.

6. The method for preparing a crack-free environmental barrier coating according to claim 1, characterized in that, The suspension solvent uses a combustible organic solvent, including one or more combinations of alcohol, gasoline, acetone, and diethyl ether.

7. The method for preparing a crack-free environmental barrier coating according to claim 6, characterized in that, The average particle size of the environmental barrier coating powder material is less than or equal to 2 μm, and the solid content in the resulting suspension is 5% to 40%.

8. The method for preparing a crack-free environmental barrier coating according to claim 7, characterized in that, The method of using the suspension as the spraying material for the environmental barrier coating structure and performing plasma spraying on the coating substrate to a preset coating thickness using a plasma spray gun includes: The matrix material is preheated by turning on the plasma spray gun without any suspension input; the matrix material is a SiC ceramic matrix composite material, and the preheating temperature does not exceed 800°C. After preheating, ensure the plasma spray gun continuously heats the substrate material, using nitrogen at 50-300 slpm, argon at 20-100 slpm, and helium at 15-60 slpm as the plasma working gas. Simultaneously, activate the suspension injection of the plasma spray gun to spray the environmental barrier coating. The deposition temperature is controlled at 1000℃-1300℃, and the suspension injection rate is 10-150 ml / min. By controlling the injection rate of the suspension, the porosity of the environmental barrier coating is controlled within the range of 5%-30%. After spraying, stop injecting the suspension and use the plasma flame of the suspension plasma spray gun to continuously heat the environmental barrier coating. Reduce the surface temperature of the coating sample to 800℃ within a preset time. After keeping the coating sample at this temperature for 3-10 minutes, turn off the spray gun and allow the coating sample to cool naturally to room temperature. This completes the preparation of the environmental barrier coating and yields an environmental barrier coating without vertical through cracks.

9. The method for preparing a crack-free environmental barrier coating according to claim 8, characterized in that, The number of spraying cycles is controlled to keep the thickness of the environmental barrier coating within the range of 50-300 μm.

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