Suspension plasma spray based vertical crack free environmental barrier coating method

Abstract

The present application relates to the technical field of high-temperature protective coating, and discloses a preparation method of a vertical crack-free environmental barrier coating based on suspension plasma spraying, which comprises the following steps: constructing a substrate material, respectively constructing a deposition temperature-based environmental barrier coating quenching stress analysis model, a thermal mismatch stress analysis model and a thermal gradient stress analysis model during the environmental barrier coating coating process by using suspension plasma spraying, determining a target function of the stress level of the environmental barrier coating by summing up the output values of the three analysis models, and obtaining the optimal control value of the deposition temperature in the plasma spraying process by optimizing the target function, so as to reduce the stress level in the environmental barrier coating. The method can avoid the generation of vertical cracks in the environmental barrier coating and improve the performance of the environmental barrier coating.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-temperature protective coating, and discloses a vertical crack-free environmental barrier coating preparation method based on suspension plasma spraying. BACKGROUND

[0002] SiC f / SiC m Ceramic matrix composites (CMC) are becoming the next generation of hot candidate materials for high-temperature structural materials of aero-engines due to their light weight, good high-temperature mechanical properties and high-temperature oxidation resistance. At present, the surface of the CMC material is oxidized in dry air to form a dense SiO2 oxide film to protect the substrate from further oxidation, so the CMC material has good high-temperature oxidation resistance in dry air. The long-term use temperature of the CMC material can reach 1300 DEG C. However, the aero-engine gas environment contains a large amount of water vapor, and the CMC material will rapidly corrode in a high-temperature water-oxygen environment, causing the CMC material to rapidly degrade, and the degradation rate can reach dozens of microns / hour.

[0003] The current solution is to coat a layer of water-oxygen isolation environmental barrier coating on the CMC material, which is dense in structure. The current environmental barrier coating mainly uses rare earth silicate materials such as Yb2Si2O7, Yb2SiO5 and Y2SiO5. The most commonly used environmental barrier coating preparation method is plasma spraying technology, including atmospheric plasma spraying, suspension plasma spraying technology, vacuum plasma spraying and plasma spraying physical vapor deposition. Plasma spraying technology uses plasma flame as a heat source to heat and melt ceramic powder to a molten or semi-molten state, and finally accelerates the impact on the substrate surface to cool and solidify on the substrate surface to form a coating.

[0004] As shown in Figure 1 , the existing environmental barrier coating is prone to vertical cracks during preparation, which will damage the integrity of the coating and become a rapid channel for high water-oxygen gas invasion. The invading high-temperature water-oxygen gas will quickly contact the substrate, causing rapid corrosion and degradation of the substrate, and producing gas volatiles, which will cause the coating to peel off. The exposed CMC substrate will be rapidly corroded and degraded in the gas environment, causing the CMC substrate to rapidly fail. A high-performance environmental barrier coating must be dense in structure and free of vertical cracks to effectively resist water vapor invasion. Therefore, in order to prolong the service life and service reliability of the CMC substrate, an environmental barrier coating that isolates water vapor must be prepared on the surface of the CMC substrate. SUMMARY

[0005] The present application aims to provide a suspension plasma spraying based vertical crack free environmental barrier coating preparation method, 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] In order to achieve the above technical effects, the technical scheme adopted by the present application is:

[0007] The suspension plasma spraying based vertical crack free environmental barrier coating preparation method comprises:

[0008] According to the performance parameters of the environmental barrier coating powder material and the deposition temperature of the environmental barrier coating under plasma spraying conditions, a deposition temperature based environmental barrier coating quenching stress analysis model is constructed;

[0009] According to the performance parameters of the environmental barrier coating structure and the material performance parameters of the substrate coated by the environmental barrier coating structure, a deposition temperature based environmental barrier coating thermal mismatch stress analysis model is constructed;

[0010] According to the performance parameters of the environmental barrier coating structure, the material performance parameters of the substrate coated by the environmental barrier coating structure, and the temperature gradient change value between the surface temperature of the substrate material and the internal temperature of the substrate material under the corresponding deposition temperature condition during the deposition process, a deposition temperature based environmental barrier coating thermal gradient stress analysis model is constructed;

[0011] Taking the deposition temperature as the design variable, 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 is minimized as the optimization goal, and the optimal control value of the deposition temperature is obtained by analysis;

[0012] 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 of the environmental barrier coating structure, and the coating substrate is plasma sprayed to a preset coating thickness by using a plasma spray gun to complete the preparation of the environmental barrier coating; wherein the deposition temperature of the environmental barrier coating is controlled by adjusting the swing speed and swing amplitude of the plasma spray gun during the plasma spraying process, so that the absolute deviation between the deposition temperature and the optimal control value is not greater than a preset deviation threshold.

[0013] Further, the deposition temperature based environmental barrier coating quenching stress analysis model constructed is wherein is the quenching stress of the environmental barrier coating structure when the deposition temperature is during the plasma spraying process, is the Poisson's ratio of the environmental barrier coating powder material, is the elastic modulus of the environmental barrier coating powder material, is the thermal expansion coefficient of the environmental barrier coating powder material, the melting point of the environmental barrier coating powder material.

[0014] Further, the constructed environmental barrier coating thermal mismatch stress analysis model based on the deposition temperature is wherein is the deposition temperature in the plasma spraying process is the thermal mismatch stress of the environmental barrier coating structure when the deposition temperature is is the Poisson's ratio of the environmental barrier coating structure after deposition, is the elastic modulus of the environmental barrier coating structure, is the thermal expansion coefficient of the environmental barrier coating powder material, is the thermal expansion coefficient of the substrate material, is the deposition environmental temperature in the plasma spraying process.

[0015] Further, the constructed environmental barrier coating thermal gradient stress analysis model based on the deposition temperature is wherein is the thermal gradient stress generated in the coating when the coating surface temperature is cooled from to after the completion of the plasma spraying, is the deposition temperature of the coated substrate surface when the spraying is completed, at which time the corresponding internal temperature of the coated substrate is , is the surface deposition temperature when the temperature gradient changes the most, is the internal temperature of the coated substrate when the temperature gradient changes the most, is the Poisson's ratio of the environmental barrier coating structure after deposition, is the elastic modulus of the environmental barrier coating structure, is the thermal expansion coefficient of the environmental barrier coating structure.

[0016] Further, the environmental barrier coating powder material includes one or more combinations of Yb2Si2O7, YYbSi2O7, Yb2SiO5, Y2SiO5, La2Hf2O7, Gd2Si2O7, mullite, and BSAS ceramic powder.

[0017] Further, the solvent of the suspension uses a combustible organic solvent, including one or more combinations of alcohol, gasoline, acetone, and diethyl ether.

[0018] Further, 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%.

[0019] Further, the method for using the suspension as the spraying raw material of the environmental barrier coating structure and adopting a plasma spraying gun to perform plasma spraying on the coated substrate to a preset coating thickness includes:

[0020] Preheat the substrate material by opening the plasma torch without suspension input in advance; the substrate material is SiC ceramic matrix composite, and the preheating temperature is not more than 800 DEG C;

[0021] After preheating, ensure that the plasma torch continues to heat the substrate material, and use 50-300 slpm of nitrogen, 20-100 slpm of argon and 15-60 slpm of helium as the plasma working gas, and at the same time, open the suspension injection of the plasma torch to perform environmental barrier coating spraying; wherein the deposition temperature is controlled at 1000 DEG C-1300 DEG C, the suspension injection rate is 10-150 ml / min, and the porosity of the environmental barrier coating is controlled within 5%-30% by controlling the injection speed of the suspension;

[0022] After spraying, stop the injection of the suspension, continuously heat the environmental barrier coating by using the plasma flame of the suspension plasma torch, reduce the surface temperature of the coating sample to 800 DEG C within a preset time, keep the coating sample at temperature for 3-10 min, then close the torch, and naturally cool the coating sample to room temperature, to complete the preparation of the environmental barrier coating and obtain the environmental barrier coating without vertical penetrating cracks.

[0023] Further, control the spraying cycle number to make the thickness of the environmental barrier coating within 50-300 mu m.

[0024] Compared with the prior art, the present application has the beneficial effects that: the present application constructs the environmental barrier coating quenching stress analysis model, the thermal mismatch stress analysis model and the thermal gradient stress analysis model based on the deposition temperature during the environmental barrier coating coating process of the substrate material by plasma spraying, determines the sum of the output values of the three analysis models as the objective function of the environmental barrier coating stress level, optimizes the objective function to obtain the optimal control value of the deposition temperature in the plasma spraying process, so as to reduce the stress level in the environmental barrier coating, and further avoid the generation of vertical cracks in the environmental barrier coating, and improve the performance of the environmental barrier coating. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is a cross-sectional microstructure diagram of the existing environmental barrier coating;

[0026] Figure 2 It is a flow chart of the suspension plasma spraying based vertical crack free environmental barrier coating preparation method in embodiment 1 or 2;

[0027] Figure 3 It is a microstructure diagram of the Si bonding layer in embodiment 2;

[0028] Figure 4Microstructure of the environmental barrier coating without vertical crack prepared in Example 2. DETAILED DESCRIPTION

[0029] The application will be further described in conjunction with the examples and drawings. However, it should not be understood that the above-mentioned subject matter of the application is limited to the following examples. Any technology realized based on the content of the application falls within the scope of the application.

[0030] Example 1

[0031] Reference Figures 1 to 2 The method for preparing the environmental barrier coating without vertical crack based on suspension plasma spraying includes:

[0032] According to 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 of the environmental barrier coating based on the deposition temperature is constructed;

[0033] According to the performance parameters of the environmental barrier coating structure and the material performance parameters of the substrate coated by the environmental barrier coating structure, a thermal mismatch stress analysis model of the environmental barrier coating based on the deposition temperature is constructed;

[0034] According to the performance parameters of the environmental barrier coating structure, the material performance parameters of the substrate coated by the environmental barrier coating structure, and the temperature gradient change value between the surface temperature of the substrate material and the internal temperature of the substrate material under the corresponding deposition temperature condition in the deposition process, a thermal gradient stress analysis model of the environmental barrier coating based on the deposition temperature is constructed;

[0035] Taking the deposition temperature as the design variable, 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 as the optimization objective, and the minimum value as the optimal control value of the deposition temperature is obtained by analysis.

[0036] 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 of the environmental barrier coating structure. The coating substrate is plasma sprayed to a preset coating thickness by using a plasma torch. The preparation of the environmental barrier coating is completed. During the plasma spraying process, the deposition temperature of the environmental barrier coating is controlled by adjusting the swing speed and swing amplitude of the plasma torch, so that the absolute deviation between the deposition temperature and the optimal control value is not greater than a preset deviation threshold.

[0037] In the embodiment, by constructing a quenching stress analysis model of the environmental barrier coating based on the deposition temperature, a thermal mismatch stress analysis model and a thermal gradient stress analysis model in the process of coating the environmental barrier coating by plasma spraying of the base material respectively, the sum of the output values of the three analysis models is determined as a target function of the stress level of the environmental barrier coating, and by optimizing the target function, the optimal control value of the deposition temperature in the plasma spraying process is obtained to reduce the stress level in the environmental barrier coating. In addition, the spraying parameters such as the spraying gun power, the spraying distance, the spraying gun swing range and other process parameters can be adjusted and optimized to match the spraying parameters with the optimal deposition temperature in the spraying process, and finally the vertical cracks in the environmental barrier coating are avoided and the performance of the environmental barrier coating is improved.

[0038] Embodiment 2

[0039] Referring to Figures 2-4 , the Yb2Si2O7 environmental barrier coating powder material is taken as an example, and the Yb2Si2O7 environmental barrier coating is prepared on a SiC / SiC ceramic matrix composite substrate (30*30*3mm 3 ). The process of the method for preparing the environmental barrier coating without vertical cracks based on the suspension plasma spraying of the present application is described in detail, and the operation process of the insulator is as follows:

[0040] Step one, according to the performance parameters of the environmental barrier coating powder material and the deposition temperature of the environmental barrier coating under the plasma spraying condition, a quenching stress analysis model of the environmental barrier coating based on the deposition temperature is constructed.

[0041] In the embodiment, the quenching stress analysis model of the environmental barrier coating based on the deposition temperature is , wherein is the quenching stress of the environmental barrier coating structure when the deposition temperature is in the process of plasma spraying, is the Poisson ratio of the environmental barrier coating powder material, is the elastic modulus of the environmental barrier coating powder material, is the thermal expansion coefficient of the environmental barrier coating powder material, is the melting point of the environmental barrier coating powder material.

[0042] Step two, according to the performance parameters of the environmental barrier coating structure and the material performance parameters of the base material coated with the environmental barrier coating structure, a thermal mismatch stress analysis model of the environmental barrier coating based on the deposition temperature is constructed.

[0043] In the embodiment, the thermal mismatch stress analysis model of the environmental barrier coating based on the deposition temperature is , wherein is the thermal mismatch stress of the environmental barrier coating structure when the deposition temperature 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.

[0044] 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.

[0045] In this embodiment, the constructed environmental barrier coating thermal gradient stress analysis model based on deposition temperature is as follows: ,in After plasma spraying, the surface temperature of the coating 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 5.3 Place the SiC / SiC ceramic matrix composite substrate (30*30*3mm) to be sprayed. 3 The 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.

[0051] 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.

[0052] 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%.

[0053] 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.

[0054] 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.

[0055] 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 scope of protection 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. ,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; 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 deposition temperature is constructed. ,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; 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 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 deposition temperature is constructed. ,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; 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, 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.

3. 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.

4. The method for preparing a crack-free environmental barrier coating according to claim 3, 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%.

5. The method for preparing a crack-free environmental barrier coating according to claim 4, 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.

6. The method for preparing a crack-free environmental barrier coating according to claim 5, 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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