Preparation Method of Thermal Barrier Coating with Long Service Life and High Interface Bonding Strength

Abstract

An embodiment of the present invention discloses a preparation method of a thermal barrier coating with long service life and high interfacial bonding strength, including: Step 1: Preheat the superalloy substrate to make the surface temperature of the superalloy substrate reach a preset temperature, and spray metal bond coat powder onto the surface of the superalloy substrate by supersonic flame spraying method to form a metal bond coat; Step 2: Deposit a ceramic layer by spraying ceramic powder onto the surface of the metal bond coat through atmospheric plasma spraying method. In the present invention, supersonic flame spraying technology is used to prepare the bond coat. By selecting appropriate spraying powder particle size and controlling the substrate temperature, the preparation of a bond coat with high density and high surface roughness can be achieved simultaneously, which can not only ensure the oxidation resistance of the thermal barrier coating, but also improve the interfacial bonding strength between the interfacial bond coat and the ceramic surface layer, so as to realize the one-step forming of a thermal barrier coating with long service life and high interfacial bonding strength. The present invention has the advantages of simple process flow and low cost.

Description

Technical Field

[0001] The present invention relates to the field of thermal barrier coatings, and particularly to a preparation method of a thermal barrier coating with long service life and high interfacial bonding strength. Background Art

[0002] High interfacial roughness is crucial for improving the interfacial bonding and service life of thermal barrier coatings. Currently, the method of using a double-layer bond coat is mainly adopted to prepare a thermal barrier coating with high interfacial roughness: a dense NiCoCrAlY layer sprayed with finer powder is used on the side close to the substrate, aiming to provide sufficient supply of Al element to ensure the formation of a continuous and dense alumina film during service; a rough layer is obtained by spraying coarser powder on the side close to the ceramic layer, with slightly lower density, aiming to form a higher interfacial roughness to ensure good bonding force with the ceramic layer. The method of double-layer bond coat requires the use of spraying powders with different particle sizes and different spraying parameters, so the process is complex and the preparation cost is high. In recent years, the method of laser cladding of the bond coat has also been used to improve the interfacial roughness of thermal barrier coatings (CN104451672B), but it is necessary to pre-spray and prepare a metal bond coat on the surface of the superalloy substrate first. However, the high laser energy is easy to penetrate the bond coat and damage the substrate, thus destroying the composition and mechanical properties of the substrate and unable to achieve industrial application. Summary of the Invention

[0003] The technical problem to be solved by the embodiments of the present invention is to provide a preparation method of a thermal barrier coating with long service life and high interfacial bonding strength to achieve one-step forming of a thermal barrier coating with long service life and high interfacial bonding strength.

[0004] To solve the above technical problem, the embodiments of the present invention propose a preparation method of a thermal barrier coating with long service life and high interfacial bonding strength, including:

[0005] Step 1: Preheat the superalloy substrate to make the surface temperature of the superalloy substrate reach a preset temperature, and spray metal bond coat powder onto the surface of the superalloy substrate by supersonic flame spraying to form a metal bond coat;

[0006] Step 2: Spray ceramic powder onto the surface of the metal bond coat by air plasma spraying to deposit and form a ceramic layer.

[0007] Further, the particle size range of the metal bond coat powder is 25 μm - 40 μm.

[0008] Further, in step 1, when using supersonic flame spraying, first perform sandblasting on the surface of the superalloy substrate; the preset temperature range is 500 - 800 °C, the distance between the supersonic flame spray gun and the superalloy substrate is 220 - 250 mm, the moving speed range of the supersonic flame spray gun is 1500 - 1800 mm / s, the powder feeding rotation speed is 2 r / min, the propane pressure is 90 - 95 PSI, the air pressure is 95 - 100 PSI, the hydrogen pressure is 25 - 30 PSI, and the nitrogen pressure is 40 - 50 PSI.

[0009] Further, step 1 includes the following sub - steps:

[0010] (1) Use a thermal imaging non - contact temperature measuring instrument to monitor the surface temperature of the superalloy substrate in real - time. First, pre - heat the superalloy substrate with a supersonic flame without powder feeding;

[0011] (2) Use compressed air to purge the back side of the superalloy substrate. By controlling the flow rate of the compressed air on the back side of the superalloy substrate, when the surface temperature of the superalloy substrate reaches the preset temperature, start powder feeding and spraying;

[0012] (3) When the moving path of the supersonic flame spray gun completely covers the surface of the superalloy substrate once, it is recorded as one spraying; after each spraying is completed, stop spraying, and measure the thickness of the metal bonding layer after the substrate cools down;

[0013] (4) Repeat sub - steps (1) to (3) to control the final thickness of the metal bonding layer within 150 - 200 μm, and the surface roughness Ra of the metal bonding layer is 15 - 25 μm.

[0014] Further, in sub - step (2), when purging with compressed air, the purging direction of the air gun is perpendicular to the plane of the superalloy substrate, the flow rate of the compressed air is 40 - 70 L / min, the distance between the air gun and the superalloy substrate is 100 - 200 mm, and use a manipulator to control the moving path of the air gun to uniformly control the temperature of the superalloy substrate, and the moving speed of the air gun is 1500 - 1800 mm / s.

[0015] Further, the ceramic powder in step 2 is yttria - stabilized zirconia, wherein the mass content of Y2O3 is 8%.

[0016] Further, in Step 2, when performing atmospheric plasma spraying, first preheat the superalloy substrate, control the temperature of the superalloy substrate to 300 - 400 °C, the distance between the atmospheric plasma spray gun and the superalloy substrate is 90 - 120 mm, the moving speed of the atmospheric plasma spray gun is 800 - 1000 mm / s, the powder feeding rate is 50 - 60 g / min, the powder feeding air flow is 0.5 - 1.0 L / min, the voltage range is 180 - 200 V, the spraying current range is 250 - 300 A, the Ar gas flow rate range is 30 - 60 L / min, and the H2 gas flow rate range is 5 - 20 L / min.

[0017] Further, Step 2 includes the following sub - steps:

[0018] (a) Use a thermal imaging non - contact temperature measuring instrument to monitor the surface temperature of the superalloy substrate in real - time, heat the superalloy substrate with the atmospheric plasma flame, and use compressed air to purge the back side of the superalloy substrate. Control the temperature by controlling the flow rate of the compressed air on the back side of the superalloy substrate. When the surface temperature of the superalloy substrate reaches 300 - 400 °C, start powder feeding and spraying; One pass of the moving path of the atmospheric plasma spray gun covering the surface of the metal bonding layer of the superalloy substrate is recorded as one spraying; After each spraying, stop spraying, and measure the thickness of the ceramic layer after cooling;

[0019] (b) Repeat sub - step (a) to control the final thickness of the ceramic layer to 200 - 300 μm, and the surface roughness Ra of the ceramic layer is 15 - 25 μm.

[0020] Further, when purging with compressed air in sub - step (a), the air gun is perpendicular to the plane of the superalloy substrate, the distance between the air gun and the superalloy substrate is 100 - 150 mm, and use a manipulator to control the moving path of the air gun to uniformly control the temperature of the superalloy substrate. The moving speed of the air gun is 800 - 1000 mm / s, and the flow rate of the compressed air is 70 - 80 L / min.

[0021] The beneficial effects of the present invention are as follows: The present invention utilizes the supersonic flame spraying technology. By cooling the back side of the superalloy substrate with compressed air, controlling the gas flow rate and distance, controlling the surface temperature of the substrate, and using a relatively fine particle size of the sprayed powder, a bonding layer with high density and high surface roughness is prepared, and a ceramic coating is prepared by atmospheric plasma spraying. The high - density bonding layer can ensure the oxidation resistance of the thermal barrier coating, and at the same time, the high surface roughness can improve the interfacial bonding strength between the interfacial bonding layer and the ceramic surface layer, thereby realizing the one - step forming of a long - life and high - interfacial - bonding - strength thermal barrier coating; The present invention has the characteristics of simple process flow and low cost, and can realize large - scale industrial application. Description of the Drawings

[0022] Figure 1 It is a schematic cross-sectional structure diagram of a thermal barrier coating with long lifespan and high interfacial bonding strength according to an embodiment of the present invention.

[0023] Figure 2 It is a surface topography diagram of a thermal barrier coating with long lifespan and high interfacial bonding strength according to an embodiment of the present invention. Detailed implementation manners

[0024] It should be noted that, without conflict, the embodiments and features in the embodiments of this application can be combined with each other. The present invention will be further described in detail below with reference to the attached Figure 1 、the attached Figure 2 drawings and specific embodiments.

[0025] The metal bond coat powder of the present invention can adopt the commonly used metal bond coat powder in the art, preferably NiCoCrAlY. The preset temperature is preferably 700 °C. Embodiment 1

[0026] (1) The superalloy substrate is subjected to sandblasting. After sandblasting, the superalloy substrate is preheated by high velocity oxy-fuel spraying. The distance between the spray gun and the superalloy substrate is 230 mm, the particle size of the sprayed powder is 25 - 40 μm, the moving speed of the spray gun is 1500 mm / s, the powder feeding rotation speed is 2 r / min, the propane pressure is 92 PSI, the air pressure is 95 PSI, the hydrogen pressure is 25 PSI, and the nitrogen pressure is 45 PSI.

[0027] (2) The back side of the superalloy substrate is purged with compressed air. The flow rate of the compressed air is 65 - 70 L / min, and the surface temperature is controlled at 500 °C. The distance between the air gun and the superalloy substrate is 150 mm, and the moving speed of the air gun is 1500 mm / s.

[0028] (3) After each spraying, the spraying is stopped. When the surface temperature reaches 500 °C under the action of flame heating and back airflow cooling, the spraying is restarted. Repeat the above operations, and finally control the thickness of the metal bond coat to be 150 - 200 μm.

[0029] (4) The ceramic layer is prepared on the surface of the bond coat by atmospheric plasma spraying technology. The ceramic layer is yttria-stabilized zirconia with a mass content of 8%. During spraying, the distance between the spray gun and the substrate is 90 mm, the moving speed of the spray gun is 800 mm / s, the powder feeding rate is 50 g / min, the powder feeding air flow is 0.5 L / min, the voltage is 180 V, the spraying current is 250 A, the Ar gas flow rate is 50 L / min, and the H2 gas flow rate is 10 L / min.

[0030] (5) The back side of the substrate is purged with compressed air at a flow rate of 70 - 80 L / min, and the surface temperature is controlled at 300 - 400 °C. The distance between the air gun and the superalloy substrate is 100 mm, and the moving speed of the air gun is 800 mm / s.

[0031] (6) After each spraying, the spraying is stopped. When the surface temperature reaches 300 - 400 °C under the action of flame heating and back air flow cooling, the spraying is restarted. Repeat the above operation, and finally control the thickness of the ceramic layer to be 200 - 300 μm. Example 2

[0032] (1) The superalloy substrate is sandblasted. After sandblasting, the superalloy substrate is preheated by supersonic flame spraying. The distance between the spray gun and the superalloy substrate is 230 mm, the particle size of the sprayed powder is 25 - 40 μm, the moving speed of the spray gun is 1500 mm / s, the powder feeding rotation speed is 2 r / min, the propane pressure is 92 PSI, the air pressure is 95 PSI, the hydrogen pressure is 25 PSI, and the nitrogen pressure is 45 PSI.

[0033] (2) The back side of the superalloy substrate is purged with compressed air at a flow rate of 60 - 65 L / min, and the surface temperature is controlled at 600 °C. The distance between the air gun and the superalloy substrate is 150 mm, and the moving speed of the air gun is 1500 mm / s.

[0034] (3) After each spraying, the spraying is stopped. When the surface temperature reaches 600 °C under the action of flame heating and back air flow cooling, the spraying is restarted. Repeat the above operation, and finally control the thickness of the bonding layer to be 150 - 200 μm.

[0035] (4) The ceramic layer is prepared on the surface of the bonding layer by atmospheric plasma spraying technology. The ceramic layer is yttria-stabilized zirconia with a mass content of 8%. During spraying, the surface temperature is controlled at 300 - 400 °C, and the back compressed air flow rate is controlled at 70 - 80 L / min. The distance between the spray gun and the substrate is 90 mm, the moving speed of the spray gun is 800 mm / s, the powder feeding rate is 50 g / min, the powder feeding air flow is 0.5 L / min, the voltage is 180 V, the spraying current is 250 A, the Ar gas flow rate is 50 L / min, and the H2 gas flow rate is 10 L / min.

[0036] (5) The back side of the superalloy substrate is purged with compressed air at a flow rate of 70 - 80 L / min, and the surface temperature is controlled at 300 - 400 °C. The distance between the air gun and the superalloy substrate is 100 mm, and the moving speed of the air gun is 800 mm / s.

[0037] (6) After each spraying is completed, stop spraying. When the surface temperature reaches 300 - 400 °C under the action of flame heating and back air flow cooling, start spraying again. Repeat the above operation, and finally control the thickness of the ceramic layer to be 200 - 300 μm. Example 3

[0038] (1) The superalloy substrate is subjected to sandblasting. After sandblasting, the superalloy substrate is preheated by supersonic flame spraying. The distance between the spray gun and the superalloy substrate is 230 mm, the particle size of the spraying powder is 25 - 40 μm, the moving speed of the spray gun is 1500 mm / s, the powder feeding rotation speed is 2 r / min, the propane pressure is 92 PSI, the air pressure is 95 PSI, the hydrogen pressure is 25 PSI, and the nitrogen pressure is 45 PSI.

[0039] (2) The back side of the superalloy substrate is purged with compressed air. The flow rate of the compressed air is 55 - 60 L / min, and the surface temperature is controlled at 700 °C. The distance between the air gun and the superalloy substrate is 200 mm, and the moving speed of the air gun is 1500 mm / s.

[0040] (3) After each spraying is completed, stop spraying. When the surface temperature reaches 700 °C under the action of flame heating and back air flow cooling, start spraying again. Repeat the above operation, and finally control the thickness of the bonding layer to be 150 - 200 μm.

[0041] (4) The ceramic layer is prepared on the surface of the bonding layer by atmospheric plasma spraying technology. The ceramic layer is yttria-stabilized zirconia with a mass content of 8%. During spraying, the surface temperature is controlled at 300 - 400 °C, and the back compressed air flow rate is controlled at 70 - 80 L / min. The distance between the spray gun and the substrate is 90 mm, the moving speed of the spray gun is 800 mm / s, the powder feeding rate is 50 g / min, the powder feeding air flow is 0.5 L / min, the voltage is 180 V, the spraying current is 250 A, the Ar gas flow rate is 50 L / min, and the H2 gas flow rate is 10 L / min.

[0042] (5) The back side of the substrate is purged with compressed air. The flow rate of the compressed air is 70 - 80 L / min, and the surface temperature is controlled at 300 - 400 °C. The distance between the air gun and the superalloy substrate is 100 mm, and the moving speed of the air gun is 800 mm / s.

[0043] (6) After each spraying is completed, stop spraying. When the surface temperature reaches 300 - 400 °C under the action of flame heating and back air flow cooling, start spraying again. Repeat the above operation, and finally control the thickness of the ceramic layer to be 200 - 300 μm. Example 4

[0044] (1)Sandblast the superalloy substrate. After sandblasting, preheat the superalloy substrate by supersonic flame spraying. The distance between the spray gun and the superalloy substrate is 230 mm, the particle size of the sprayed powder is 25 - 40 μm, the moving speed of the spray gun is 1500 mm / s, the powder feeding rotation speed is 2 r / min, the propane pressure is 92 PSI, the air pressure is 95 PSI, the hydrogen pressure is 25 PSI, and the nitrogen pressure is 45 PSI.

[0045] (2)Blow the back side of the superalloy substrate with compressed air. The flow rate of the compressed air is 45 - 50 L / min, and the surface temperature is controlled at 750 °C. The distance between the air gun and the superalloy substrate is 200 mm, and the moving speed of the air gun is 1500 mm / s.

[0046] (3)After each spraying is completed, stop spraying. When the surface temperature reaches 750 °C under the action of flame heating and back - side air flow cooling, start spraying again. Repeat the above operation, and finally control the thickness of the bonding layer to be 150 - 200 μm.

[0047] (4)Prepare a ceramic layer on the surface of the bonding layer by atmospheric plasma spraying technology. The ceramic layer is yttria - stabilized zirconia with a mass content of 8%. During spraying, the surface temperature is controlled at 300 - 400 °C, and the back - side compressed air flow rate is controlled at 70 - 80 L / min. The distance between the spray gun and the substrate is 90 mm, the moving speed of the spray gun is 800 mm / s, the powder feeding rate is 50 g / min, the powder feeding air flow is 0.5 L / min, the voltage is 180 V, the spraying current is 250 A, the Ar gas flow rate is 50 L / min, and the H2 gas flow rate is 10 L / min.

[0048] (5)Blow the back side of the substrate with compressed air. The flow rate of the compressed air is 70 - 80 L / min, and the surface temperature is controlled at 300 - 400 °C. The distance between the air gun and the superalloy substrate is 100 mm, and the moving speed of the air gun is 800 mm / s.

[0049] (6)After each spraying is completed, stop spraying. When the surface temperature reaches 300 - 400 °C under the action of flame heating and back - side air flow cooling, start spraying again. Repeat the above operation, and finally control the thickness of the ceramic layer to be 200 - 300 μm.

[0050] Comparative Example 1

[0051] (1)Sandblast the superalloy substrate. After sandblasting, preheat the superalloy substrate by supersonic flame spraying. The distance between the spray gun and the superalloy substrate is 230 mm, the particle size of the sprayed powder is 25 - 40 μm, the moving speed of the spray gun is 1500 mm / s, the powder feeding rotation speed is 2 r / min, the propane pressure is 92 PSI, the air pressure is 95 PSI, the hydrogen pressure is 25 PSI, and the nitrogen pressure is 45 PSI.

[0052] (2)Do not purge the back side of the superalloy substrate with compressed air, do not control the substrate temperature, spray continuously for five times, and then stop spraying. Repeat the above operations, and finally control the thickness of the bonding layer to be 150 - 200 μm.

[0053] (3)Prepare a ceramic layer on the surface of the bonding layer by atmospheric plasma spraying technology. The ceramic layer is yttria-stabilized zirconia with a mass content of 8%. During spraying, the distance between the spray gun and the substrate is 90 mm, the moving speed of the spray gun is 800 mm / s, the powder feeding rate is 50 g / min, the powder feeding air flow is 0.5 L / min, the voltage is 180 V, the spraying current is 250 A, the Ar gas flow rate is 50 L / min, and the H2 gas flow rate is 10 L / min.

[0054] (4)Do not purge the back side of the superalloy substrate with compressed air, do not control the substrate temperature, spray continuously for five times, and then stop spraying. Repeat the above operations, and finally control the thickness of the ceramic layer to be 200 - 300 μm.

[0055] Perform performance tests on the coatings prepared in the present invention, and the results are shown in Table 1. From Figure 1 、 Figure 2 and the results in Table 1, it can be seen that increasing the spraying surface temperature can improve the surface roughness and increase the thermal cycle life. However, when the temperature reaches 750 °C, the surface roughness begins to decrease, and at the same time, the oxygen content in the bonding layer increases significantly, and the thermal cycle life of the thermal barrier coating decreases. Considering the above results, the optimal spraying temperature should be controlled at about 700 °C.

[0056] Table 1

[0057]

[0058] The bonding strength of the coatings of the present invention is tested in accordance with the American standard ASTM C633 - 2001 "Test Method for Adhesion or Cohesive Strength of Thermal Spray Coatings".

[0059] The thermal cycle life test of the thermal barrier coating is carried out in accordance with ISO 1418-2012 "Metallic and other inorganic coatings—Test methods for measuring thermal cycle resistance and thermal shock resistance for thermal barrier coatings". The test conditions are as follows: keep the temperature at 1100 °C for 50 minutes, and then air-cool for 10 minutes. The number of cycles when the spalling area of the thermal barrier coating exceeds 30% is its thermal cycle life.

[0060] In the present invention, the bond coat is prepared by using the high velocity oxy-fuel spraying technology. By selecting appropriate spray powder particle sizes and controlling the substrate temperature, the preparation of a bond coat with high density and high surface roughness can be achieved simultaneously. This can not only ensure the oxidation resistance of the thermal barrier coating but also improve the interfacial bonding strength between the interfacial bond coat and the ceramic top coat, thus realizing the one-step forming of a thermal barrier coating with long life and high interfacial bonding strength. Compared with the prior art, the technology proposed by the present invention has the advantages of simple process flow and low cost.

[0061] The present invention describes the technical solution completely and clearly through examples, but it does not constitute a limitation to the present invention. Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalent scope.

Claims

1. A preparation method of a thermal barrier coating with long service life and high interfacial bonding strength, characterized in that, Including: Step 1: Preheat the superalloy substrate to make the surface temperature of the superalloy substrate reach a preset temperature, and spray the metal bonding layer powder onto the surface of the superalloy substrate by the high-velocity oxygen fuel spraying method to form a metal bonding layer; Step 2: Spray the ceramic powder onto the surface of the metal bonding layer by the atmospheric plasma spraying method to deposit and form a ceramic layer; The particle size range of the metal bonding layer powder is 25 μm - 40 μm; In Step 1, when using the high-velocity oxygen fuel spraying, first perform sandblasting treatment on the surface of the superalloy substrate; the range of the preset temperature is 500 - 800 °C, the distance between the high-velocity oxygen fuel spray gun and the superalloy substrate is 220 - 250 mm, the moving speed range of the high-velocity oxygen fuel spray gun is 1500 - 1800 mm / s, the powder feeding rotation speed is 2 r / min, the propane pressure is 90 - 95 PSI, the air pressure is 95 - 100 PSI, the hydrogen pressure is 25 - 30 PSI, and the nitrogen pressure is 40 - 50 PSI; Step 1 includes the following sub-steps: (1) Use a thermal imaging non-contact thermometer to monitor the surface temperature of the superalloy substrate in real time. First, preheat the superalloy substrate with the high-velocity oxygen fuel without powder feeding; (2) Blow the back side of the superalloy substrate with compressed air. By controlling the flow rate of the compressed air on the back side of the superalloy substrate, when the surface temperature of the superalloy substrate reaches the preset temperature, start powder feeding and spraying; (3) The moving path of the high-velocity oxygen fuel spray gun covering the surface of the superalloy substrate once is recorded as one spraying; after each spraying is completed, stop spraying, and measure the thickness of the metal bonding layer after the substrate cools down; (4) Repeat sub-steps (1) - (3) to control the final thickness of the metal bonding layer within 150 - 200 μm, and the surface roughness Ra of the metal bonding layer is 15 - 25 μm.

2. The preparation method of the thermal barrier coating with long service life and high interfacial bonding strength as described in claim 1, characterized in that, In sub-step (2), when blowing with compressed air, the blowing direction of the air gun is perpendicular to the plane of the superalloy substrate, the flow rate of the compressed air is 40 - 70 L / min, the distance between the air gun and the superalloy substrate is 100 - 200 mm, and use a manipulator to control the moving path of the air gun to uniformly control the temperature of the superalloy substrate, and the moving speed of the air gun is 1500 - 1800 mm / s.

3. The method for preparing a thermal barrier coating having a long service life and high interface bonding strength according to claim 1, wherein: The ceramic powder in Step 2 is yttria-stabilized zirconia, where the mass content of Y2O3 is 8%.

4. The preparation method of the thermal barrier coating with long service life and high interfacial bonding strength according to claim 1, characterized in that In Step 2, when performing atmospheric plasma spraying, first preheat the superalloy substrate, control the temperature of the superalloy substrate to 300 - 400 °C, the distance between the atmospheric plasma spray gun and the superalloy substrate is 90 - 120 mm, the moving speed of the atmospheric plasma spray gun is 800 - 1000 mm / s, the powder feeding rate is 50 - 60 g / min, the powder feeding air flow is 0.5 - 1.0 L / min, the voltage range is 180 - 200 V, the spraying current range is 250 - 300 A, the Ar gas flow rate range is 30 - 60 L / min, and the H2 gas flow rate range is 5 - 20 L / min.

5. The method for preparing a thermal barrier coating having a long service life and high interface bonding strength according to claim 4, wherein: Step 2 includes the following sub-steps: (a)The surface temperature of the superalloy substrate is monitored in real time using a thermal imaging non-contact thermometer. The superalloy substrate is heated by an atmospheric plasma flame, and compressed air is used to purge the back side of the superalloy substrate. The temperature is controlled by controlling the flow rate of the compressed air on the back side of the superalloy substrate. When the surface temperature of the superalloy substrate reaches 300 - 400 °C, powder feeding and spraying are started; One pass of the moving path of the atmospheric plasma spray gun covering the surface of the metal bonding layer of the superalloy substrate is recorded as one spraying; After each spraying is completed, spraying is stopped, and the thickness of the ceramic layer is measured after cooling. (b)Repeat sub-step (a) to control the final thickness of the ceramic layer within 200 - 300 μm, and the surface roughness Ra of the ceramic layer is 15 - 25 μm.

6. The method for preparing a thermal barrier coating having a long service life and high interface bonding strength according to claim 5, wherein: When purging with compressed air in sub-step (a), the air gun is perpendicular to the plane of the superalloy substrate, the distance between the air gun and the superalloy substrate is 100 - 150 mm, and the moving path of the air gun is controlled by a manipulator to uniformly control the temperature of the superalloy substrate. The moving speed of the air gun is 800 - 1000 mm / s, and the flow rate of the compressed air is 70 - 80 L / min.

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