A high-strength vapor-oxidation-resistant coating material and its coating, preparation method and application

Abstract

The application discloses a high-strength anti-vapor oxidation coating material and a coating, a preparation method and application thereof, and belongs to the technical field of anticorrosion of inner walls of through-flow components of thermal power generating units. The high-strength anti-vapor oxidation coating material disclosed by the application is composed of solid-phase components and liquid-phase components, and each component cooperatively plays a role, improves the anti-vapor oxidation performance of the coating, and strengthens the mechanical performance of the coating, so as to prevent cracking of the coating during service, and solves the problem of cracking of the existing coating in a high-temperature environment.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of anti-corrosion of inner wall of flow passage components of thermal power generating units, and particularly relates to a high-strength anti-steam oxidation coating material, a coating, a preparation method and application thereof. BACKGROUND

[0002] The flow passage components of thermal power generating units usually operate under high-temperature and high-pressure conditions, especially under supercritical pressure. Water vapor and water have the same dissolution characteristics under such high-temperature and high-pressure environment, which causes the inner wall of the metal pipe of the flow passage components to be oxidized. Meanwhile, if the content of metal oxidation corrosion substances in the boiler feedwater system of the unit and various acids, alkalis and salts in the boiler feedwater cannot be strictly controlled, the oxidation process of the metal pipe will be accelerated. If no effective treatment measures are taken, a large amount of non-dense oxidation corrosion substances will be deposited on the inner wall of the high-temperature and high-pressure water vapor pipeline. Such non-dense oxidation film structure is easy to accelerate the falling, regrowth and re-falling of the oxidation film, further intensifying the oxidation process.

[0003] In view of the above phenomenon, the skilled person usually adopts the combined pipe flushing and purging treatment method by adding ammonia and oxygen. This method can cause the high-temperature water vapor to rapidly react with the metal inner wall of the pipeline, forming a dense double-layer protective oxidation film which can be tightly combined with the metal matrix without loosening and has good surface properties, so as to prevent further corrosion of the metal. However, this method needs to add chemical substances such as ammonia and oxygen and needs to be accurately purged, so the treatment cost is high and it is difficult to meet the needs of industrial operation. Some skilled persons also coat a composite coating with Cr-based components on the inner wall of the flow passage components to improve the anti-steam oxidation capacity of the flow passage components. However, with the increase of service time, the thermal stress of the coating material increases under high-temperature conditions, and the difference in thermal expansion coefficient between the coating and the base material may also cause stress concentration, resulting in the decrease of mechanical properties such as yield strength and tensile strength of the Cr coating, and further causing cracks and accelerating the corrosion of the inner wall of the flow passage components. SUMMARY

[0004] The purpose of the present application is to provide a high-strength anti-steam oxidation coating material, a coating, a preparation method and application thereof, so as to solve the technical problem of cracking of the existing coating in a high-temperature environment due to the decrease of mechanical properties.

[0005] In order to achieve the above purpose, the following technical solutions are adopted:

[0006] The present application discloses a high-strength anti-steam oxidation coating material. The composition of the high-strength anti-steam oxidation coating includes solid phase components and liquid phase components.

[0007] The solid phase components include, in terms of mass percentage:

[0008] 44%-60% Cr, 5%-30% Ni, 2%-8% Co, 3%-5% Al, 2%-10% Ti, 2%-5% Si, 2%-10% Nb and 4.4%-5% La;

[0009] The liquid phase component is a metal oxide solution.

[0010] Furthermore, the dosage ratio of the solid phase component to the liquid phase component is 10g:1-5mL.

[0011] Furthermore, the metal oxide solution is obtained by mixing a metal oxide and a solvent; the metal oxide is one or two of CrO3, MgO, Si3N4 and ZnO;

[0012] The mass fraction of the metal oxide solution is 10%-30%.

[0013] Furthermore, the solvent is one or more of Al(H2PO4) and water glass.

[0014] The present invention also discloses a method for preparing a high-strength steam oxidation resistant coating, which is prepared using the above-mentioned high-strength steam oxidation resistant coating material, comprising the following steps:

[0015] Weighing and mixing the raw materials of the solid phase component according to mass percentage to obtain the solid phase component;

[0016] Weighing the raw materials of the liquid phase component, stirring and mixing, to obtain the liquid phase component;

[0017] After mixing the solid phase component and the liquid phase component, a coating slurry is obtained;

[0018] The coating slurry is coated on the surface of the substrate, and then dried, cured and heat-treated in sequence to obtain a high-strength steam oxidation-resistant coating on the surface of the substrate.

[0019] Furthermore, the raw materials of the solid phase component are weighed according to mass percentage, mixed for 12-24 hours, and then ball milled for 6-24 hours to obtain the solid phase component;

[0020] The solid phase component and the liquid phase component are mixed, stirred for 2-4 hours, and then ball milled for 6-24 hours to obtain a coating slurry.

[0021] Furthermore, the coating pressure is 0.5-2.0 MPa; the thickness of the coating slurry is 0.1-1.0 mm; the coverage of the coating slurry on the surface of the substrate is not less than 98%;

[0022] The air-drying method is natural air-drying, and the natural air-drying time is 24-48 hours; the curing temperature is 300-450°C, and the time is 24-48 hours; the heat treatment method is high-temperature calcination, and the high-temperature calcination is carried out in an inert atmosphere at a temperature of 980-1150°C and a time of 8-15 minutes.

[0023] Furthermore, the type of the substrate is TP304H, TP347H, Super304H, TP347HFG, HR3C or nickel-iron based alloy.

[0024] The invention also discloses a high-strength steam oxidation resistant coating prepared by the preparation method.

[0025] The invention also discloses the application of the high-strength steam oxidation resistant coating in the corrosion protection of the inner wall of the flow-through components of a thermal power unit.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention discloses a high-strength steam oxidation resistant coating material, which is composed of a solid phase component and a liquid phase component. The various components work synergistically to improve the steam oxidation resistance of the Cr / Ni-Cr-based coating while strengthening its mechanical properties to prevent it from cracking during service. Ni works synergistically with other elements to form a stable solid solution structure, improve the thermal stability and thermal creep resistance of the coating, and improve its strength and plasticity. Co has a significant influence on the formed solid solution structure, enhances the grain boundary strengthening effect in the coating, and improves its high-temperature durability. Cr forms a dense oxide film at high temperatures, which can effectively prevent oxygen corrosion and oxidation reactions of the alloy matrix, thereby increasing the service life. Al and Ti are the main elements of the γ' phase in high-temperature alloys. Increasing the Al and Ti contents will increase the volume fraction of the γ' phase, increase its dissolution temperature, and transform its morphology from spherical to cubic, thereby significantly improving the high-temperature strength and solving the problem of cracking of existing coatings in high-temperature environments.

[0028] Furthermore, Al can promote the formation of Al2O3, forming a dense oxide film and improving the oxidation resistance of the alloy. Ti is one of the main forming elements of MC-type carbides, which helps to form a stable phase TiC and improve the alloy's resistance to hot corrosion.

[0029] Furthermore, La can react with non-metallic impurities in the coating to form compounds, part of which is eliminated and part of which is retained in the alloy to play a role of heterogeneous nucleation, eliminating or reducing the harm of impurities and improving the quality and purity of the coating.

[0030] The present invention also discloses a coating preparation method based on the above-mentioned high-strength steam oxidation resistant coating material. This method adopts simple coating to realize the preparation of the coating, is simple to operate, and has low cost. It can be applied to the preparation of the inner wall coating of the flow-through components with large aspect ratio, and has broad application prospects.

[0031] Furthermore, by adjusting the thickness of the coating slurry, the thickness of the coating on the substrate surface can be adjusted, and the required thickness of the coating can be flexibly prepared according to the service conditions and environment; according to relevant experimental results, applying a coating slurry of 0.1-1.0mm can form a coating of 45-62μm on the substrate surface.

[0032] Furthermore, a double-layer structure and metallurgical bonding coating is formed on the surface of the substrate by heat treatment, which significantly improves the bonding strength between the coating and the substrate and improves the oxidation resistance of the substrate in a pure water vapor environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A schematic cross-sectional view of a high-strength steam oxidation resistant coating prepared in the present invention;

[0034] Figure 2 This is the critical cracking strength data of the high-strength steam oxidation resistant coating prepared by the present invention. DETAILED DESCRIPTION

[0035] To facilitate understanding of the features and effects of the present invention by those skilled in the art, the following provides a general description and definition of the terms and expressions used in the specification and claims. Unless otherwise indicated, all technical and scientific terms used herein have the ordinary meanings as understood by those skilled in the art regarding the present invention. In the event of conflict, the definitions in this specification shall prevail.

[0036] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0037] Herein, all features such as values, amounts, amounts, and concentrations defined in numerical ranges or percentage ranges are for brevity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to include and specifically disclose all possible subranges and individual values ​​within the range (including integers and fractions).

[0038] In this document, unless otherwise specified, “include,” “including,” “contains,” “has” or similar terms cover the meanings of “consisting of” and “mainly consisting of,” for example, “A includes a” covers the meanings of “A includes a and other” and “A only includes a.”

[0039] In this document, for the sake of brevity, not all possible combinations of the various technical features in each embodiment or example are described. Therefore, as long as there are no contradictions in the combination of these technical features, the various technical features in each embodiment or example can be combined in any way, and all possible combinations should be considered to be within the scope of this specification.

[0040] A first aspect of the present invention provides a high-strength steam oxidation resistant coating material, comprising a solid phase component and a liquid phase component; wherein, in terms of mass percentage, the solid phase component comprises:

[0041] 45%-70% Cr, 5%-30% Ni, 2%-8% Co, 3%-5% Al, 2%-10% Ti, 2%-5% Si, 2%-10% Nb and 4.4%-5% La;

[0042] The liquid phase component is a metal oxide solution; the above components improve the steam oxidation resistance of the Cr / Ni-Cr based coating while strengthening its mechanical properties to prevent it from cracking during service.

[0043] Preferably, the usage ratio of the solid phase component to the liquid phase component is 10 g:1-5 mL.

[0044] Preferably, the metal oxide solution is obtained by mixing a metal oxide and a solvent; the metal oxide is one or two of CrO3, MgO, Si3N4 and ZnO, and the mass fraction of the formed metal oxide solution is 10-30%.

[0045] Preferably, the solvent is one or more of Al(H2PO4), water glass and an organic binder.

[0046] A second aspect of the present invention provides a method for preparing a coating using the above-mentioned high-strength steam oxidation resistant coating material, comprising the following steps:

[0047] According to mass percentage, 44%-60% Cr, 5%-30% Ni, 2%-8% Co, 3%-5% Al, 2%-10% Ti, 2%-5% Si, 2%-10% Nb and 4.4%-5% La are weighed, mixed for 12-24 hours, and then ball milled for 6-24 hours to obtain a solid phase component;

[0048] Weighing the raw materials of the liquid phase component, stirring and mixing, to obtain the liquid phase component;

[0049] The solid phase component and the liquid phase component are mixed, stirred for 2-4 hours, and then ball milled for 6-24 hours to obtain a coating slurry;

[0050] The coating slurry is coated on the surface of the substrate by manual coating or spin coating, and then dried, cured and heat treated in sequence to obtain a high-strength steam oxidation resistant coating on the surface of the substrate.

[0051] Preferably, the coating pressure is 0.5-2.0 MPa; the thickness of the coating slurry is 0.1-1.0 mm; the coverage of the coating slurry on the substrate surface is not less than 98%; the air-drying method is natural air-drying, and the natural air-drying time is 24-48 hours; the curing temperature is 300-450°C, and the time is 24-48 hours.

[0052] Preferably, the substrate is made of austenitic steel, such as TP304H, TP347H, Super304H, TP347HFG, HR3C, nickel-iron based alloy, etc.

[0053] Preferably, the heat treatment is performed by high-temperature sintering; the high-temperature sintering is performed at a temperature of 980-1150° C. for 8-15 minutes under the protection of an inert gas.

[0054] The third aspect of the present invention provides a high-strength steam oxidation resistant coating prepared by the above method, wherein the coating has a double-layer structure, metallurgical bonding, and a thickness of 45-62 μm.

[0055] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall equally within the scope limited by the appended claims of the application.

[0056] The following examples were prepared using conventional instruments and equipment in the art. Experimental methods in the following examples, where specific conditions are not specified, were generally performed under conventional conditions or according to the conditions recommended by the manufacturer. The various raw materials used in the following examples, unless otherwise specified, were conventional commercially available products, with specifications conventional in the art. In the present specification and the following examples, unless otherwise specified, "%" indicates percentage by weight, "part" indicates parts by weight, and "ratio" indicates weight ratio.

[0057] Example 1

[0058] A method for preparing a high-strength steam oxidation resistant coating comprises the following steps:

[0059] Step 1: Weigh 45% Cr, 30% Ni, 2% Co, 3% Al, 2% Ti, 5% Si, 8% Nb, and 5% La by mass, mix for 12 hours, and then ball mill for 12 hours to obtain a solid phase component;

[0060] Step 2: Al(H2PO4), CrO3 and MgO are mixed to obtain a liquid component, wherein the mass fraction of the liquid component is 30%;

[0061] Step 3: The solid phase component and the liquid phase component were mixed at a solid-liquid ratio of 10 g:5 mL, stirred for 4 h, and then ball milled for 12 h to obtain a coating slurry;

[0062] Step 4: Apply the coating slurry to the surface of the TP304H substrate by manual brushing at a coating pressure of 0.5 MPa to a thickness of 1.0 mm, with a coverage rate of not less than 98%;

[0063] Step 5: After natural air drying for 48 hours, the substrate was cured at 300°C for 30 hours, and then calcined at 980°C for 8 minutes under the protection of an inert atmosphere to obtain a high-strength steam oxidation resistant coating on the substrate surface.

[0064] Example 2

[0065] A method for preparing a high-strength steam oxidation resistant coating comprises the following steps:

[0066] Step 1: Weigh 50% Cr, 15.6% Ni, 8% Co, 5% Al, 10% Ti, 5% Si, 2% Nb, and 4.4% La by mass, mix for 24 hours, and then ball mill for 24 hours to obtain a solid phase component;

[0067] Step 2: Mixing water glass and Si3N4 to obtain a liquid phase component, wherein the mass fraction of the liquid phase component is 10%;

[0068] Step 3: The solid phase component and the liquid phase component were mixed at a solid-liquid ratio of 10 g:1 mL, stirred for 2 h, and then ball milled for 24 h to obtain a coating slurry;

[0069] Step 4: Apply the coating slurry to the surface of the Super304H substrate by manual brushing at a coating pressure of 2.0 MPa, with a thickness of 0.1 mm and a coverage rate of not less than 98%;

[0070] Step 5: After natural air drying for 24 hours, the substrate was cured at 450°C for 24 hours, and then calcined at 1040°C for 10 minutes under the protection of an inert atmosphere to obtain a high-strength steam oxidation resistant coating on the substrate surface.

[0071] Example 3

[0072] A method for preparing a high-strength steam oxidation resistant coating comprises the following steps:

[0073] Step 1: Weigh 60% Cr, 5% Ni, 8% Co, 5% Al, 2.6% Ti, 5% Si, 10% Nb, and 4.4% La by mass, mix for 24 hours, and then ball mill for 24 hours to obtain a solid phase component;

[0074] Step 2: Al(H2PO4), water glass, MgO, Si3N4 and ZnO are mixed to obtain a liquid phase component, wherein the mass fraction of the liquid phase component is 25%;

[0075] Step 3: The solid phase component and the liquid phase component were mixed at a solid-liquid ratio of 10 g:5 mL, stirred for 2 h, and then ball milled for 20 h to obtain a coating slurry;

[0076] Step 4: Apply the coating slurry to the surface of the TP347HFG substrate by manual brushing at a coating pressure of 2.0 MPa to a thickness of 0.5 mm, with a coverage rate of not less than 98%;

[0077] Step 5: After natural air drying for 24 hours, the substrate was cured at 450°C for 24 hours, and then calcined at 1150°C for 12 minutes under the protection of an inert atmosphere to obtain a high-strength steam oxidation resistant coating on the substrate surface.

[0078] Example 4

[0079] A method for preparing a high-strength steam oxidation resistant coating comprises the following steps:

[0080] Step 1: Weigh 60% Cr, 5% Ni, 8% Co, 5% Al, 2.6% Ti, 5% Si, 10% Nb, and 4.4% La by mass, mix for 24 hours, and then ball mill for 24 hours to obtain a solid phase component;

[0081] Step 2: Al(H2PO4), water glass, MgO, Si3N4 and ZnO are mixed to obtain a liquid phase component, wherein the mass fraction of the liquid phase component is 25%;

[0082] Step 3: The solid phase component and the liquid phase component were mixed at a solid-liquid ratio of 10 g:5 mL, stirred for 2 h, and then ball milled for 20 h to obtain a coating slurry;

[0083] Step 4: Apply the coating slurry to the surface of the TP347HFG substrate by manual brushing at a coating pressure of 2.0 MPa, with a coverage of not less than 98%;

[0084] Step 5: After natural air drying for 24 hours, the substrate was cured at 450°C for 24 hours, and then calcined at 1000°C for 10 minutes under the protection of an inert atmosphere to obtain a high-strength steam oxidation resistant coating on the substrate surface.

[0085] Example 5

[0086] A method for preparing a high-strength steam oxidation resistant coating comprises the following steps:

[0087] Step 1: 52% Cr, 13% Ni, 8% Co, 5% Al, 2.6% Ti, 5% Si, 10% Nb, and 4.4% La were weighed, mixed for 24 hours, and then ball-milled for 24 hours to obtain a solid phase component;

[0088] Step 2: Al(H2PO4), water glass, MgO, Si3N4 and ZnO are mixed to obtain a liquid phase component, wherein the mass fraction of the liquid phase component is 30%;

[0089] Step 3: The solid phase component and the liquid phase component were mixed at a solid-liquid ratio of 10 g:5 mL, stirred for 2 h, and then ball milled for 20 h to obtain a coating slurry;

[0090] Step 4: Apply the coating slurry to the surface of the TP347HFG substrate by manual brushing at a coating pressure of 2.0 MPa, with a coverage of not less than 98%;

[0091] Step 5: After natural air drying for 24 hours, the substrate was cured at 450°C for 24 hours, and then calcined at 1150°C for 15 minutes under the protection of an inert atmosphere to obtain a high-strength steam oxidation resistant coating on the substrate surface.

[0092] Example 6

[0093] A method for preparing a high-strength steam oxidation resistant coating comprises the following steps:

[0094] Step 1: Weigh 60% Cr, 5% Ni, 8% Co, 5% Al, 2.6% Ti, 5% Si, 10% Nb, and 4.4% La by mass, mix for 24 hours, and then ball mill for 24 hours to obtain a solid phase component;

[0095] Step 2: Al(H2PO4), water glass, MgO, Si3N4 and ZnO are mixed to obtain a liquid phase component, wherein the mass fraction of the liquid phase component is 25%;

[0096] Step 3: The solid phase component and the liquid phase component were mixed at a solid-liquid ratio of 10 g:5 mL, stirred for 2 h, and then ball milled for 20 h to obtain a coating slurry;

[0097] Step 4: Apply the coating slurry to the surface of the TP347HFG substrate by manual brushing at a coating pressure of 0.8 MPa to a thickness of 1.0 mm, with a coverage rate of not less than 98%;

[0098] Step 5: After natural air drying for 40 hours, the substrate was cured at 450°C for 24 hours, and then calcined at 1000°C for 10 minutes under the protection of an inert atmosphere to obtain a high-strength steam oxidation resistant coating on the substrate surface.

[0099] Example 7

[0100] A method for preparing a high-strength steam oxidation resistant coating comprises the following steps:

[0101] Step 1: Weigh 60% Cr, 5% Ni, 8% Co, 5% Al, 2.6% Ti, 5% Si, 10% Nb, and 4.4% La by mass, mix for 24 hours, and then ball mill for 24 hours to obtain a solid phase component;

[0102] Step 2: Al(H2PO4), water glass, MgO, Si3N4 and ZnO are mixed to obtain a liquid phase component, wherein the mass fraction of the liquid phase component is 25%;

[0103] Step 3: The solid phase component and the liquid phase component were mixed at a solid-liquid ratio of 10 g:5 mL, stirred for 2 h, and then ball milled for 20 h to obtain a coating slurry;

[0104] Step 4: Apply the coating slurry to the surface of the TP347HFG substrate by manual brushing at a coating pressure of 2.0 MPa to a thickness of 0.5 mm, with a coverage rate of not less than 98%;

[0105] Step 5: After natural air drying for 24 hours, the substrate was cured at 450°C for 24 hours, and then calcined at 995°C for 12 minutes under the protection of an inert atmosphere to obtain a high-strength steam oxidation resistant coating on the substrate surface.

[0106] Figure 1 This is a cross-sectional schematic diagram of the high-strength steam-oxidation-resistant coating prepared in the present invention. As can be seen from the figure, the high-strength steam-oxidation-resistant coating has a double-layer structure and is metallurgically bonded to the substrate. When the coating thickness is in the range of 0.1-1.0 mm, the coating thickness is 45-62 μm.

[0107] Figure 2 The data shown are the critical cracking strength data of the high-strength steam oxidation resistant coating prepared by the present invention. The coating prepared by the material of the present invention has high strength at room temperature and high temperature of 650°C, and can effectively reduce the occurrence of cracking.

[0108] Table 1 shows the steam oxidation resistance data of the high-strength steam oxidation resistant coatings obtained in different embodiments. It can be seen from the table that compared with the base alloy, the steam oxidation resistance of the coating is improved several times, which significantly improves the steam oxidation resistance.

[0109] Table 1 shows the steam oxidation resistance data of the high-strength steam oxidation resistant coatings obtained in different embodiments.

[0110]

[0111] The above content is only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A high-strength steam oxidation resistant coating material, characterized in that: The composition of the high-strength steam oxidation resistant coating material comprises a solid phase component and a liquid phase component; After mixing the solid phase component and the liquid phase component, a coating slurry is obtained; The coating slurry is applied to the surface of the substrate, followed by drying, curing and heat treatment in sequence to obtain a high-strength steam oxidation resistant coating on the surface of the substrate; In terms of mass percentage, the solid phase components include: 44%-60% Cr, 5%-30% Ni, 2%-8% Co, 3%-5% Al, 2%-10% Ti, 2%-5% Si, 2%-10% Nb and 4.4%-5% La; The liquid phase component is a metal oxide solution; The metal oxide solution is obtained by mixing a metal oxide and a solvent; the metal oxide is one or two of CrO3, MgO and ZnO; The mass fraction of the metal oxide solution is 10%-30%; The solvent is one or more of Al(H2PO4)3 and water glass.

2. The high-strength steam oxidation resistant coating material according to claim 1, characterized in that: The usage ratio of the solid phase component to the liquid phase component is 10 g:1-5 mL.

3. A method for preparing a high-strength steam oxidation resistant coating, characterized in that: The high-strength steam oxidation resistant coating material according to claim 1 or 2 is prepared, comprising the following steps: Weighing and mixing the raw materials of the solid phase component according to mass percentage to obtain the solid phase component; Weighing the raw materials of the liquid phase component, stirring and mixing, to obtain the liquid phase component; After mixing the solid phase component and the liquid phase component, a coating slurry is obtained; The coating slurry is coated on the surface of the substrate, and then dried, cured and heat-treated in sequence to obtain a high-strength steam oxidation-resistant coating on the surface of the substrate.

4. The method for preparing a high-strength steam oxidation resistant coating according to claim 3, characterized in that: The raw materials of the solid phase component are weighed according to mass percentage, mixed for 12-24 hours, and then ball milled for 6-24 hours to obtain the solid phase component; The solid phase component and the liquid phase component are mixed, stirred for 2-4 hours, and then ball milled for 6-24 hours to obtain a coating slurry.

5. The method for preparing a high-strength steam oxidation resistant coating according to claim 3, wherein: The coating pressure is 0.5-2.0 MPa; the thickness of the coating slurry is 0.1-1.0 mm; the coverage of the coating slurry on the substrate surface is not less than 98%; The drying method is natural air drying, and the natural air drying time is 24-48 hours; the curing temperature is 300-450°C, and the time is 24-48 hours; the heat treatment method is high-temperature calcination, and the high-temperature calcination is carried out in an inert atmosphere at a temperature of 980-1150°C and a time of 8-15 minutes.

6. The method for preparing a high-strength steam oxidation resistant coating according to claim 3, characterized in that: The substrate is made of TP304H, TP347H, Super304H, TP347HFG, HR3C or nickel-iron based alloy.

7. A high-strength steam oxidation resistant coating, characterized in that: The method is prepared by any one of claims 3 to 6.

8. Use of the high-strength steam oxidation resistant coating according to claim 7 in the corrosion protection of the inner wall of flow components of thermal power units.

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