Thermal barrier coating with vertical columnar crystal structure and preparation method thereof

Abstract

The invention discloses a thermal barrier coating with a vertical columnar crystal structure and a preparation method of the thermal barrier coating. The preparation method comprises the following steps: substrate pretreatment: cleaning, coarsening, activating and pre-oxidizing the surface of a substrate; spraying: preparing a bonding layer of the thermal barrier coating on the pretreated substrate by adopting a plasma spraying or hypersonic flame spraying technology, and preparing a ceramic layer of the thermal barrier coating by adopting the plasma spraying technology; in the ceramic layer spraying process, low-temperature gas is sprayed to the surface of the coating, so that the coating is rapidly cooled, and a vertical columnar crystal structure is formed; performing sol-gel hole sealing: coating the surface of the coating with the sol-gel solution, converting the sol-gel solution into a compact oxide layer through heat treatment, and filling micropores and cracks on the surface; and heat treatment: the coating is subjected to heat treatment, residual stress is eliminated, and the bonding strength and durability of the coating are improved. The strain tolerance, the surface quality and the corrosion resistance of the coating are remarkably improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermal barrier coatings, and in particular relates to a thermal barrier coating with a vertical columnar crystal structure and a preparation method thereof. Background Art

[0002] Thermal barrier coatings (TBCs) are a key coating technology used in high-temperature environments. They protect metal substrates from high-temperature oxidation, thermal corrosion, and thermal fatigue, while significantly reducing substrate temperatures and improving component thermal efficiency and lifespan. TBCs deposit a layer of low-thermal-conductivity ceramic material on the surface of a metal substrate, creating a thermal barrier that reduces heat transfer from the high-temperature environment to the substrate.

[0003] Thermal barrier coatings have important applications in high-temperature components, but their performance in high-temperature and corrosive environments still needs to be further improved. Traditional thermal barrier coatings have the following problems:

[0004] The coating's durability in high temperature and corrosive environments is insufficient, and it is prone to peeling and failure;

[0005] Even after laser remelting, micropores and cracks may still exist on the coating surface, which may lead to the penetration of corrosive media and reduce the corrosion resistance of the coating. Summary of the Invention

[0006] To solve the above problems, the present invention provides a thermal barrier coating and a preparation method thereof that combines low-temperature gas cooling and sol-gel sealing technology, which significantly improves the strain tolerance, surface quality and corrosion resistance of the coating.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for preparing a thermal barrier coating having a vertical columnar crystal structure comprises the following steps:

[0009] The first step is substrate pretreatment: cleaning, roughening, activation and pre-oxidation of the substrate surface;

[0010] The second spraying process: plasma spraying or supersonic flame spraying technology is used to prepare the bonding layer of the thermal barrier coating on the pretreated substrate, and plasma spraying technology is used to prepare the ceramic layer of the thermal barrier coating. During the spraying process of the ceramic layer, low-temperature gas is sprayed onto the coating surface to rapidly cool the coating and form a vertical columnar crystal structure.

[0011] The third step is sol-gel sealing: the sol-gel solution is applied to the coating surface and converted into a dense oxide layer through heat treatment to fill the surface micropores and cracks;

[0012] The fourth step is heat treatment: heat treatment of the coating to eliminate residual stress and improve the bonding strength and durability of the coating.

[0013] A further improvement of the present invention is that the substrate surface cleaning is performed by using ultrasound in an acetone or ethanol organic solvent to remove grease, pollutants, fine particles and impurities from the substrate surface.

[0014] A further improvement of the present invention is that the substrate surface is roughened using 20-50 micron aluminum oxide or silicon carbide sand particles.

[0015] A further improvement of the present invention is that the sandblasting pressure during the roughening of the substrate surface is 2.0-3.5 Pa and the sandblasting angle is 45-90°, so as to achieve a surface roughness of 3-6 microns.

[0016] A further improvement of the present invention is that the substrate surface activation adopts a plasma cleaning machine with a radio frequency or microwave plasma source, using argon, oxygen, nitrogen or a mixed gas with a gas purity of ≥99.99%, a power of 50-500W, a gas pressure of 10-100Pa, a processing time of 5-30 minutes, a gas flow rate of 10-100sccm, the substrate temperature is controlled at 50-150°C, and the distance between the electrode and the substrate is 5-20cm.

[0017] A further improvement of the present invention is that the substrate surface is pre-oxidized at a temperature of 800-1200° C. for a time of 30 minutes to 2 hours.

[0018] A further improvement of the present invention is that the atmosphere during the pre-oxidation treatment of the substrate surface is air or oxygen, wherein the oxygen concentration is 20%-100%, and the cooling rate is 5°C / min-10°C / min.

[0019] A further improvement of the present invention is that the low-temperature gas is argon, nitrogen or helium, the gas temperature is -50°C-0°C, the gas pressure is 0.2-0.8 MPa, the gas flow rate is 10-50 L / min, the cooling rate is greater than 500°C / s, the gas injection angle is 45°-90°, the distance between the cooling gas nozzle and the coating surface is in the range of 50-200 mm, the injection time is related to the spraying speed and coating thickness, and the nozzle diameter is between 1-5 mm.

[0020] A further improvement of the present invention is that in the third step, the coating product obtained in the second step is immersed and pulled in silica sol or aluminum sol to obtain a uniform sol layer on its surface. After repeating this process 3-8 times, it is heated and calcined at a temperature of 300-600°C for 1-2 hours to form a uniform SiO2 or Al2O3 film on the coating surface.

[0021] A thermal barrier coating with a vertical columnar crystal structure is prepared by adopting the preparation method.

[0022] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0023] The present invention provides a thermal barrier coating with a vertical columnar crystal structure and a preparation method thereof. By spraying low-temperature gas onto the coating surface during the spraying of the ceramic layer, the coating is rapidly cooled to form a vertical columnar crystal structure. This structure can better adapt to the thermal stress generated during the thermal cycle, reduce stress concentration within the coating, and thus improve the strain tolerance and thermal shock resistance of the coating. The vertical columnar crystal structure can effectively prevent the expansion of cracks in the coating and improve the overall stability of the coating. The vertical columnar crystal structure may affect the thermal conductivity of the coating to a certain extent, which helps to further optimize the thermal insulation performance of the coating. The bonding between the vertical columnar crystal structure and the substrate may be tighter, which helps to improve the bonding strength of the coating.

[0024] Furthermore, sol-gel sealing technology effectively fills the micropores and cracks on the coating surface by applying a sol-gel solution to the coating surface and converting it into a dense oxide layer through heat treatment. These micropores and cracks are the main channels for the penetration of corrosive media, and filling them can significantly improve the corrosion resistance of the coating. The dense oxide layer can form a protective barrier, preventing direct contact between the corrosive media and the substrate, thereby extending the service life of the coating. Sol-gel sealing technology can smooth the coating surface and improve the coating's appearance quality. The conversion of the sol-gel into a dense oxide layer through heat treatment further enhances the density of the coating, helping to improve the overall performance of the coating.

[0025] Furthermore, the bonding and ceramic layers are prepared using plasma spraying or supersonic oxygen fuel spraying. These mature and highly controllable processes ensure uniformity and consistency of the coating. By precisely controlling the injection parameters of the cryogenic gas, the cooling rate of the coating can be precisely controlled, thereby optimizing the formation of the vertical columnar crystal structure.

[0026] In summary, the present invention utilizes low-temperature gas cooling technology to form a tiny vertical columnar crystal structure in the thermal barrier coating, improving the coating's strain tolerance and thermal shock resistance. Sol-gel sealing technology effectively fills micropores and cracks on the coating surface, significantly enhancing the coating's corrosion resistance. The thermal barrier coating prepared by this method exhibits excellent thermal shock resistance, high strain tolerance, and high corrosion resistance, making it suitable for long-term use in high-temperature and corrosive environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 The figure is a schematic diagram of the process flow of a method for preparing a thermal barrier coating with a vertical columnar crystal structure according to the present invention. DETAILED DESCRIPTION

[0029] Hereinafter, only certain exemplary embodiments are briefly described. As will be appreciated by those skilled in the art, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and description are to be considered as illustrative in nature and not restrictive.

[0030] In the description of the present invention, it should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or collections thereof.

[0031] It should also be understood that the terms used in the present specification are only for the purpose of describing particular embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0032] It should be further understood that the term "and / or" used in the present description and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0033] The accompanying drawings illustrate various schematic diagrams of structures according to embodiments disclosed herein. These figures are not drawn to scale; for clarity, some details are exaggerated and some details may be omitted. The shapes of the various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art may design regions / layers with different shapes, sizes, and relative positions as needed.

[0034] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0035] The present invention provides a method for preparing a thermal barrier coating having a vertical columnar crystal structure, comprising the following steps:

[0036] The first step is substrate pretreatment: cleaning, roughening, activation and pre-oxidation of the substrate surface;

[0037] The second spraying process uses plasma spraying or supersonic flame spraying technology to prepare the bonding layer of the thermal barrier coating, and plasma spraying technology is used to prepare the ceramic layer of the thermal barrier coating. During the spraying of the ceramic layer, low-temperature gas is sprayed onto the coating surface to quickly cool the coating and form a vertical columnar crystal structure.

[0038] The third step is sol-gel sealing: the sol-gel solution is applied to the coating surface and converted into a dense oxide layer through heat treatment to fill the surface micropores and cracks;

[0039] The fourth step is heat treatment: heat treatment of the coating to eliminate residual stress and further improve the bonding strength and durability of the coating.

[0040] The substrate surface cleaning is to use ultrasound in an organic solvent such as acetone or ethanol to remove grease, pollutants, fine particles and impurities on the substrate surface. The core principle is: high-frequency ultrasound (usually 20-40kHz) generates tiny bubbles in the liquid, and the shock waves and microjets released when the bubbles burst can peel off surface attachments. Acetone, ethanol, etc. have strong solubility for grease and organic pollutants, and can quickly penetrate and dissolve pollutants. The mechanical force of ultrasound combined with the chemical dissolution effect of the solvent can efficiently remove micron-sized particles and stubborn pollutants. Ultrasonic organic solvent cleaning is a key step in the pretreatment of thermal barrier coating substrates. Its high efficiency, comprehensiveness and non-damage characteristics make it the preferred method in the industry. By optimizing solvent selection, ultrasonic parameters and cleaning process, the bonding strength between the coating and the substrate can be significantly improved, and the service life of the coating can be extended.

[0041] The substrate surface roughening is performed by using 20-50 micron aluminum oxide or silicon carbide sand particles, a sandblasting pressure of 2.0-3.5 Pa, and a sandblasting angle of 45-90° to achieve a surface roughness of 3-6 microns. Sandblasting roughening is to impact the substrate surface with high-speed sand particles to produce a uniform microscopic concave-convex structure on the surface, thereby: improving the mechanical bite force between the coating and the substrate; the rough surface can enhance the adhesion of the coating material and reduce the risk of coating peeling; and sandblasting can remove weak bonding interfaces such as oxide layers and work hardening layers to improve coating reliability. Sandblasting roughening is an important step in the pretreatment of thermal barrier coating substrates. By reasonably selecting the sand particle type, particle size, sandblasting pressure and angle, an ideal surface roughness (3-6 microns) can be obtained, which significantly improves the bonding strength between the coating and the substrate. In practical applications, it is necessary to optimize the sandblasting process parameters according to the substrate material, coating type and production requirements, and pay attention to surface cleaning and quality control after sandblasting to ensure the stability and reliability of the coating performance.

[0042] The substrate surface activation is performed using a plasma cleaner equipped with a radio frequency or microwave plasma source. Argon, oxygen, nitrogen, or a mixed gas with a purity of ≥99.99% is used. The power is 50-500W, the pressure is 10-100Pa, the treatment time is 5-30 minutes, the gas flow rate is 10-100sccm, the substrate temperature is controlled at 50-150°C, and the distance between the electrode and the substrate is 5-20cm. Plasma activation is a key step in the pretreatment of thermal barrier coating substrates. By precisely controlling parameters such as gas type, power, pressure, and treatment time, the substrate surface cleanliness and chemical activity can be significantly improved, thereby enhancing the bonding strength between the coating and the substrate. In practical applications, the activation process parameters must be optimized based on the substrate material, coating type, and production requirements, and attention must be paid to surface quality control after activation to ensure the stability and reliability of the coating performance.

[0043] The substrate surface pre-oxidation treatment is performed at a temperature of 800-1200°C for 30 minutes to 2 hours in an air or oxygen atmosphere with an oxygen concentration of 20% to 100%, and at a cooling rate of 5°C / min to 10°C / min. Substrate surface pre-oxidation is a key step in the preparation of thermal barrier coatings. By properly controlling the treatment temperature, time, atmosphere, and cooling rate, a high-quality oxide film can be formed, significantly improving the bonding strength and oxidation resistance of the coating to the substrate. In practical applications, pre-oxidation process parameters must be optimized based on the substrate material, coating type, and production requirements, and attention must be paid to oxide film quality control to ensure the stability and reliability of coating performance.

[0044] Plasma spraying uses a direct current-driven plasma arc as a heat source to heat materials such as ceramics, alloys, and metals to a molten or semi-molten state. The plasma arc is then sprayed at high speed onto a pre-treated workpiece surface, forming a firmly adherent surface layer. The plasma arc is generated by an arc discharge within the spray gun, ionizing a working gas (such as argon or nitrogen) to form a high-temperature, high-velocity plasma jet.

[0045] Supersonic fuel spraying involves mixing a gaseous or liquid fuel with high-pressure oxygen and then burning it in a specific combustion chamber or nozzle. The resulting high-temperature, high-velocity flame is used for spraying. The spray gun consists of three parts: a combustion chamber (which fully heats and accelerates the spray material particles), a Laval nozzle (which accelerates the flame to supersonic speeds), and a nozzle of uniform cross-section (which also fully heats and accelerates the spray material particles).

[0046] The low-temperature gas is argon, nitrogen or helium, the gas temperature is -50℃-0℃, the gas pressure is 0.2-0.8MPa, the gas flow rate is 10-50L / min, the cooling rate is greater than 500℃ / s, the gas injection angle is 45°-90°, the distance between the cooling gas nozzle and the coating surface is in the range of 50-200mm, the injection time is related to the spraying speed and the coating thickness, and the nozzle diameter is between 1-5mm. Low-temperature gas rapid cooling technology is a key link in the preparation of thermal spray coatings. By precisely controlling parameters such as gas type, temperature, pressure, flow rate, injection angle and nozzle distance, the coating performance can be significantly improved (such as inhibiting phase change, reducing residual stress, controlling oxidation, etc.). In actual applications, it is necessary to optimize the cooling process parameters according to the coating material, geometry and production requirements, and pay attention to problems such as surface erosion, uniformity and equipment frosting during the cooling process.

[0047] In the third step, the coating product obtained in the second step is dipped and pulled into silica sol or aluminum sol to obtain a uniform sol layer on its surface. After repeating this process 3-8 times, it is heated and calcined at 300-600°C for 1-2 hours to form a uniform SiO2 or Al2O3 film on the surface of the coating. Depositing SiO2 or Al2O3 films on the surface of thermal spray coatings through the sol-gel method can significantly improve the density, oxidation resistance, corrosion resistance and thermal barrier properties of the coating. In actual applications, it is necessary to optimize parameters such as sol type, number of dips and pulls, calcination temperature and time according to the coating material, application environment and performance requirements, and pay attention to solving problems such as film cracking, peeling and porosity control.

[0048] Example 1:

[0049] The DZ411 nickel-based high-temperature alloy substrate was ultrasonically cleaned with acetone solution for 30 minutes, and then the substrate surface was roughened by sandblasting with alumina sand particles with a particle size of 30 μm, a pressure of 3.0 Pa, and an angle of 75° to achieve a roughness of 4.2 μm. It was then activated by argon plasma with a power of 300 W, a gas pressure of 50 Pa, and a gas flow rate of 80 sccm for 20 minutes, and then pre-oxidized in an air atmosphere at 1050°C for 1 hour.

[0050] A NiCrAlY bonding layer with a thickness of 100 μm was prepared by supersonic flame spraying. When an 8 wt.% yttria-stabilized zirconia (8YSZ) ceramic layer coating was prepared by plasma spraying, -30°C argon was sprayed simultaneously, with a cooling gas pressure of 0.5 MPa, a flow rate of 30 L / min, a nozzle diameter of 3 mm, a distance of 150 mm from the workpiece, and an angle of 60°. The cooling rate reached 600°C / s, forming a vertical columnar crystal structure with a columnar crystal width of 2-5 μm, which penetrated the thickness of the ceramic layer coating.

[0051] The thermal barrier coating with a vertical columnar crystal structure was subjected to thermal shock testing. The specimens were held at a test temperature of 1100°C ± 5°C for 5–10 minutes. After the temperature stabilized, they were removed and rapidly quenched in water at 20°C ± 5°C for 5–10 minutes. After the temperature stabilized, they were removed and reheated in a high-temperature furnace, and this cycle was repeated. The thermal shock test results showed that the thermal barrier coating with a vertical columnar crystal structure showed no peeling after 200 cycles. In contrast, a thermal barrier coating prepared without the rapid cooling method cracked after 95 cycles. The strain tolerance of the thermal barrier coating with a vertical columnar crystal structure was improved by 110%.

[0052] Example 2:

[0053] The DZ411 nickel-based superalloy substrate was ultrasonically cleaned in acetone for 30 minutes. The surface was then roughened using 30μm alumina grit at a pressure of 3.0 Pa and a 75° angle to a roughness of 4.2μm. The substrate was then activated with an argon plasma at 300W power, 50Pa pressure, and 80sccm flow for 20 minutes. The substrate was then pre-oxidized in air at 1050°C for 1 hour. Following substrate pretreatment, an 8YSZ ceramic layer with 8% porosity was plasma-sprayed without cryogenic gas cooling. The resulting thermal barrier coating was then immersed in a silica sol solution with a pH of 3.5 and pulled five times at a speed of 2 mm / s, with a 10-minute interval between each step. The coating was then calcined at 500°C for 1.5 hours, forming a dense SiO2 film approximately 200nm thick.

[0054] The prepared thermal barrier coating was subjected to a salt spray test using a 5% NaCl solution at 35°C. The salt spray test showed that the corrosion rate of the sol-gel sealed coating was reduced to one-tenth that of the unsealed coating, and electrochemical impedance spectroscopy (EIS) revealed an increase of two orders of magnitude in low-frequency impedance.

[0055] Example 3:

[0056] The titanium alloy substrate was ultrasonically cleaned with an ethanol solution for 30 minutes, and then the surface of the substrate was sandblasted with silicon carbide particles with a particle size of 40 μm to make the roughness reach 5 μm. It was then activated by nitrogen plasma with a power of 200 W, a pressure of 50 Pa, and a gas flow of 50 sccm for 30 minutes, and then pre-oxidized in an oxygen atmosphere at 1000°C for 30 minutes.

[0057] A NiCrAlY bonding layer with a thickness of 100 μm was prepared by supersonic flame spraying. When plasma spraying the La2Zr2O7 ceramic layer, nitrogen at -20°C was sprayed simultaneously with a cooling gas pressure of 0.6 MPa and a flow rate of 40 L / min. The cooling gas nozzle had a diameter of 4 mm, a distance of 150 mm from the workpiece, and an angle of 60°, forming a columnar crystal structure with a height / width ratio of >20. The prepared thermal barrier coating was alternately impregnated with aluminum sol three times and silica sol twice, and then calcined at 600°C for 1 hour to obtain an Al2O3-SiO2 composite sealing layer.

[0058] The thermal shock resistance test of the prepared thermal barrier coating with a vertical columnar crystal structure was conducted. The sample was kept at a test temperature of 1200℃±5℃ for 5-10 minutes. After the sample temperature stabilized, it was removed and quickly immersed in water at a temperature of 20℃±5℃ for 5-10 minutes to quench. After the sample temperature stabilized, it was removed and placed in a high-temperature furnace for heating again. The process was repeated. The thermal shock test results showed that the coating showed no significant shedding after 300 thermal shock cycles. At the same time, the corrosion weight loss rate in an acidic environment (pH=1) was less than 0.1mg / cm 2 .

[0059] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, from all points of view, the embodiments should be regarded as illustrative and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes that fall within the meaning and range of equivalents of the claims are included in the present invention. Any reference signs in the claims should not be construed as limiting the claim to which they relate.

[0060] In addition, it should be understood that although this specification describes the embodiments, not every embodiment contains only one independent technical solution. This description is for clarity only. Those skilled in the art should consider the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only for the purpose of illustrating the technical concept of the present invention and cannot be used to limit the scope of protection of the present invention. Any changes made based on the technical solution in accordance with the technical concept proposed by the present invention fall within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a thermal barrier coating having a vertical columnar crystal structure, characterized in that: The following steps are involved: The first step is substrate pretreatment: cleaning, roughening, activation and pre-oxidation of the substrate surface; The second step is spraying process: plasma spraying or supersonic flame spraying technology is used to prepare the bonding layer of the thermal barrier coating on the pretreated substrate, and plasma spraying technology is used to prepare the ceramic layer of the thermal barrier coating; During the spraying process of the ceramic layer, low-temperature gas is sprayed onto the coating surface to rapidly cool the coating and form a vertical columnar crystal structure; The third step is sol-gel sealing: the sol-gel solution is applied to the coating surface and converted into a dense oxide layer through heat treatment to fill the surface micropores and cracks; The fourth step is heat treatment: heat treatment of the coating to eliminate residual stress and improve the bonding strength and durability of the coating.

2. The method for preparing a thermal barrier coating having a vertical columnar crystal structure according to claim 1, characterized in that: The substrate surface cleaning is to remove grease, pollutants, fine particles and impurities on the substrate surface by using ultrasonic waves in an acetone or ethanol organic solvent.

3. The method for preparing a thermal barrier coating having a vertical columnar crystal structure according to claim 1, characterized in that: The substrate surface is roughened by using 20-50 micron aluminum oxide or silicon carbide sand particles.

4. The method for preparing a thermal barrier coating having a vertical columnar crystal structure according to claim 3, characterized in that: The sandblasting pressure during the roughening of the substrate surface is 2.0-3.5 Pa and the sandblasting angle is 45-90°, so as to achieve a surface roughness of 3-6 microns.

5. The method for preparing a thermal barrier coating having a vertical columnar crystal structure according to claim 1, characterized in that: The substrate surface activation adopts a plasma cleaning machine with a radio frequency or microwave plasma source, using argon, oxygen, nitrogen or a mixed gas with a gas purity of ≥99.99%, a power of 50-500W, a gas pressure of 10-100Pa, a processing time of 5-30 minutes, a gas flow rate of 10-100sccm, the substrate temperature is controlled at 50-150°C, and the distance between the electrode and the substrate is 5-20cm.

6. The method for preparing a thermal barrier coating having a vertical columnar crystal structure according to claim 1, characterized in that: The substrate surface pre-oxidation treatment temperature is 800-1200° C., and the time is 30 minutes-2 hours.

7. The method for preparing a thermal barrier coating having a vertical columnar crystal structure according to claim 6, characterized in that: The atmosphere during the pre-oxidation treatment of the substrate surface is air or oxygen, wherein the oxygen concentration is 20%-100%, and the cooling rate is 5°C / min-10°C / min.

8. The method for preparing a thermal barrier coating having a vertical columnar crystal structure according to claim 1, characterized in that: The low-temperature gas is argon, nitrogen or helium, the gas temperature is -50℃-0℃, the gas pressure is 0.2-0.8MPa, the gas flow rate is 10-50L / min, the cooling rate is greater than 500℃ / s, the gas injection angle is 45°-90°, the distance between the cooling gas nozzle and the coating surface is 50-200mm, the injection time is related to the spraying speed and coating thickness, and the nozzle diameter is between 1-5mm.

9. The method for preparing a thermal barrier coating having a vertical columnar crystal structure according to claim 1, characterized in that: In the third step, the coating product obtained in the second step is immersed in silica sol or aluminum sol and pulled to obtain a uniform sol layer on its surface. After repeating 3-8 times, it is heated and calcined at a temperature of 300-600°C for 1-2 hours to form a uniform SiO2 or Al2O3 film on the coating surface.

10. A thermal barrier coating having a vertical columnar crystal structure, characterized in that: The preparation method according to any one of claims 1 to 9 is used for preparation.

Images