A nanometer high-temperature anti-oxidation coating for electrolytic aluminum anode carbon and its preparation method

Abstract

The present invention discloses a nanometer high-temperature anti-oxidation coating for electrolytic aluminum anode carbon and a preparation method thereof. The nanometer high-temperature anti-oxidation coating comprises a composite binder, boron nitride-coated aluminum dioxide, modified diatomaceous earth, silicon carbide, zirconium dioxide, potassium feldspar, lanthanum oxide, a dispersant, a film-forming agent, and water. The composite binder is prepared from water glass, 3-aminopropyltriethoxysilane, and silicon dioxide in a mass ratio of (7-9):(2-5):(1-2). In the present invention, 3-aminopropyltriethoxysilane can form a network structure with silicon dioxide and water glass through chemical bonding, thereby improving the interfacial bonding strength of the composite binder, enhancing its stability and compatibility, thereby helping to improve the adhesion of the coating and reduce the probability of cracking or falling off in high-temperature environments. When applied to electrolytic aluminum anode carbon, the nanometer high-temperature anti-oxidation coating can impart significant high-temperature anti-oxidation properties to the electrolytic aluminum anode carbon, thereby extending its service life.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, and in particular to a nanometer high-temperature anti-oxidation coating for electrolytic aluminum anode carbon and a preparation method thereof. Background Art

[0002] In aluminum production, a mixture of molten cryolite and alumina serves as the electrolyte, with carbon as the anode and graphite as the cathode. Direct current is applied to the electrodes of an electrolytic cell, and an electrochemical reaction occurs. The anode products are primarily carbon dioxide and carbon monoxide gases, while the cathode product is molten aluminum. This molten aluminum is extracted from the cell via a vacuum ladle and transported to the foundry. After purification and clarification in a holding furnace, it is cast into aluminum ingots or directly processed into wire billets, profiles, and other materials. Carbon is a key raw material in the electrolytic aluminum industry. Because carbon is primarily composed of carbon, it is susceptible to anodic oxidation at high temperatures, increasing net carbon anode consumption. This can also cause the electrolytic cell to overheat and leak, which can, in severe cases, lead to safety accidents. Therefore, the quality and operating condition of carbon anodes significantly impact the normal operation of the electrolytic cell, as well as economic and technical indicators such as current efficiency, energy consumption, and primary aluminum grade. Improving the oxidation resistance of carbon anodes is crucial.

[0003] In the prior art, a protective coating is formed by coating the surface of carbon to reduce the loss of carbon, but there are still problems such as poor high-temperature oxidation resistance and unsatisfactory coating quality. Summary of the Invention

[0004] Based on this, in order to solve the problems of poor high-temperature anti-oxidation performance and unsatisfactory coating quality of coatings prepared by the prior art, the present invention provides a nano high-temperature anti-oxidation coating for electrolytic aluminum anode carbon and a preparation method thereof. The specific technical solution is as follows:

[0005] A nanometer high-temperature anti-oxidation coating for electrolytic aluminum anode carbon, the nanometer high-temperature anti-oxidation coating comprising the following raw materials in parts by weight:

[0006] 37 to 40 parts of composite binder, 12 to 15 parts of boron nitride coated alumina, 7 to 9 parts of modified diatomaceous earth, 10 to 13 parts of silicon carbide, 6 to 10 parts of zirconium dioxide, 9 to 10 parts of potassium feldspar, 3 to 5 parts of lanthanum oxide, 6 to 9 parts of dispersant, 1 to 2 parts of film-forming agent, and 30 to 50 parts of water;

[0007] The composite adhesive is prepared from water glass, 3-aminopropyltriethoxysilane and silicon dioxide in a mass ratio of (7-9): (2-5): (1-2).

[0008] Furthermore, the composite adhesive is prepared by uniformly mixing water glass, 3-aminopropyltriethoxysilane and silicon dioxide, heating to 75°C to 90°C, stirring at a speed of 500r / min to 1000r / min for 1h to 3h, and naturally cooling to obtain the composite adhesive.

[0009] Furthermore, the preparation method of the boron nitride-coated alumina is as follows: boric acid and urea are added to a solvent, stirred evenly to form a BN precursor sol, and then alumina is dispersed in the BN precursor sol, stirred at a stirring speed of 50r / min~100r / min for 30min~60min, and dried to obtain a precursor / alumina complex; and calcined at 800℃~1200℃ in a nitrogen atmosphere to obtain boron nitride-coated alumina.

[0010] Furthermore, the solvent is a mixture of water and methanol in a volume ratio of 1:1.

[0011] Furthermore, the mass ratio of the boric acid, urea and aluminum dioxide is (1-7): (1-5): (1-3).

[0012] Furthermore, the dispersant is at least one of sodium silicate, sodium carbonate, sodium stearate, polyacrylamide and sodium polyacrylate.

[0013] Furthermore, the film-forming agent is at least one of polyurethane, polyacrylate and polyvinyl pyrrolidone.

[0014] In addition, the present application also provides a method for preparing a nano high-temperature anti-oxidation coating, the preparation method comprising the following steps:

[0015] Add the composite binder, dispersant, film-forming agent and water into a stirring kettle, and stir at a magnetic stirring speed of 200 r / min to 500 r / min for 1 h to 2 h to obtain a mixture A;

[0016] The boron nitride-coated aluminum dioxide, modified diatomaceous earth, silicon carbide, zirconium dioxide, potassium feldspar and lanthanum oxide are uniformly mixed to obtain a mixture B;

[0017] Under stirring conditions, the mixture B is added to the mixture A, the speed of magnetic stirring is adjusted to 800 r / min to 1000 r / min, and stirring is carried out for 1 h to 3 h, followed by ultrasonic treatment to obtain a nano high-temperature anti-oxidation coating.

[0018] Furthermore, the frequency of the ultrasonic treatment is 23KHz~26KHz, the power of the ultrasonic treatment is 25W~50W, and the time of the ultrasonic treatment is 15min~20min.

[0019] Furthermore, the density of the nano high temperature anti-oxidation coating is 1.2 kg / m 3 ~1.5kg / m 3 .

[0020] Compared with the prior art, this application has the following beneficial effects:

[0021] 1. In the present invention, water glass, 3-aminopropyltriethoxysilane and silicon dioxide are used to prepare a composite adhesive. 3-aminopropyltriethoxysilane can form a network structure with silicon dioxide and water glass through chemical bonding, thereby improving the interfacial bonding strength of the composite adhesive, enhancing its stability and compatibility, thereby helping to improve the adhesion of the coating and reduce the probability of cracking or falling off in a high-temperature environment.

[0022] 2. The present invention optimizes the composition and ratio of the nano high-temperature anti-oxidation coating to obtain a coating with excellent coating performance and significant high-temperature anti-oxidation performance. When applied to electrolytic aluminum anode carbon, it can give the electrolytic aluminum anode carbon significant high-temperature anti-oxidation performance, thereby extending its service life. Specifically, boron nitride-coated alumina has a core-shell structure and has more excellent heat resistance. It synergizes with silicon carbide. The valence bond of silicon carbide is extremely strong and can still maintain a high bonding strength under high temperature conditions. It has excellent thermal conductivity and can significantly improve the high-temperature application performance of the coating. The addition of modified diatomaceous earth can act as a filler to increase the mechanical properties of the coating, and interact with potassium feldspar to help improve the density and mechanical properties of the coating. Zirconium dioxide transforms from monoclinic crystals to tetragonal crystals at high temperatures, interacting with lanthanum oxide to make the coating's microstructure denser, which can help improve the coating's anti-oxidation properties.

[0023] 3. The overall preparation process of the nano high-temperature anti-oxidation coating for electrolytic aluminum anode carbon of the present application is simple and highly controllable. The prepared coating has better uniformity, which helps to improve storage stability and usage stability. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with its embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not limit the scope of protection of the present invention.

[0025] In one embodiment of the present invention, a nanometer high-temperature anti-oxidation coating for electrolytic aluminum anode carbon is provided. The nanometer high-temperature anti-oxidation coating comprises the following raw materials in parts by weight:

[0026] 37 to 40 parts of composite binder, 12 to 15 parts of boron nitride coated alumina, 7 to 9 parts of modified diatomaceous earth, 10 to 13 parts of silicon carbide, 6 to 10 parts of zirconium dioxide, 9 to 10 parts of potassium feldspar, 3 to 5 parts of lanthanum oxide, 6 to 9 parts of dispersant, 1 to 2 parts of film-forming agent, and 30 to 50 parts of water;

[0027] The composite adhesive is prepared from water glass, 3-aminopropyltriethoxysilane and silicon dioxide in a mass ratio of (7-9): (2-5): (1-2).

[0028] In one embodiment, the composite adhesive is prepared by uniformly mixing water glass, 3-aminopropyltriethoxysilane and silicon dioxide, heating to 75°C~90°C, and stirring at a speed of 500r / min~1000r / min for 1h~3h, and naturally cooling to obtain the composite adhesive.

[0029] In one embodiment, the preparation method of the boron nitride-coated alumina is as follows: boric acid and urea are added to a solvent, stirred evenly to form a BN precursor sol, and then alumina is dispersed in the BN precursor sol, stirred at a stirring speed of 50r / min~100r / min for 30min~60min, and dried to obtain a precursor / alumina composite; and calcined at 800℃~1200℃ in a nitrogen atmosphere to obtain boron nitride-coated alumina.

[0030] In one embodiment, the solvent is a mixture of water and methanol in a volume ratio of 1:1.

[0031] In one embodiment, the mass ratio of boric acid, urea and aluminum dioxide is (1-7): (1-5): (1-3).

[0032] In one embodiment, the modified diatomaceous earth is diatomaceous earth modified with a silane coupling agent.

[0033] In one embodiment, the dispersant is at least one of sodium silicate, sodium carbonate, sodium stearate, polyacrylamide and sodium polyacrylate.

[0034] In one embodiment, the film-forming agent is at least one of polyurethane, polyacrylate and polyvinyl pyrrolidone.

[0035] In addition, the present application also provides a method for preparing a nano high-temperature anti-oxidation coating, the preparation method comprising the following steps:

[0036] Add the composite binder, dispersant, film-forming agent and water into a stirring kettle, and stir at a magnetic stirring speed of 200 r / min to 500 r / min for 1 h to 2 h to obtain a mixture A;

[0037] The boron nitride-coated aluminum dioxide, modified diatomaceous earth, silicon carbide, zirconium dioxide, potassium feldspar and lanthanum oxide are uniformly mixed to obtain a mixture B;

[0038] Under stirring conditions, the mixture B is added to the mixture A, the speed of magnetic stirring is adjusted to 800 r / min to 1000 r / min, and stirring is carried out for 1 h to 3 h, followed by ultrasonic treatment to obtain a nano high-temperature anti-oxidation coating.

[0039] In one embodiment, the frequency of the ultrasonic treatment is 23KHz~26KHz, the power of the ultrasonic treatment is 25W~50W, and the time of the ultrasonic treatment is 15min~20min.

[0040] In one embodiment, the density of the nano high temperature anti-oxidation coating is 1.2 kg / m 3 ~1.5kg / m 3 .

[0041] In one embodiment, the nano high temperature anti-oxidation coating is applied to the surface of the electrolytic aluminum anode carbon.

[0042] The nano high-temperature antioxidant coating prepared by the above scheme has excellent coating performance when applied to the surface of carbon, and has stable performance and significant high-temperature antioxidant performance, which can effectively extend the service life of carbon.

[0043] The present invention is further described below by way of specific examples, which are merely exemplary and do not constitute any limitation on the scope of protection of the present invention.

[0044] In the following examples and comparative examples, all reagents, materials and instruments used are commercially available unless otherwise specified. Example 1

[0045] A method for preparing a nano high-temperature anti-oxidation coating, comprising the following steps:

[0046] Water glass, 3-aminopropyltriethoxysilane and silicon dioxide in a mass ratio of 7:3:1 were uniformly mixed, heated to 80°C, stirred at a speed of 500 r / min for 3 hours, and naturally cooled to obtain a composite adhesive;

[0047] Boric acid and urea were added to a solvent (a mixture of water and methanol in a volume ratio of 1:1) and stirred to form a BN precursor sol. Alumina was then dispersed in the BN precursor sol and stirred at a stirring speed of 100 r / min for 50 minutes. After drying, a precursor / alumina composite was obtained. The composite was calcined at 1000°C in a nitrogen atmosphere to obtain boron nitride-coated alumina, wherein the mass ratio of the boric acid, urea, and alumina was 7:5:2.

[0048] 37 parts of composite adhesive, 6 parts of sodium silicate, 2 parts of polyacrylate and 30 parts of water were added to a stirring kettle according to weight ratio, and stirred at a magnetic stirring speed of 500 r / min for 2 hours to obtain a mixture A;

[0049] 12 parts of boron nitride-coated alumina, 7 parts of modified diatomaceous earth, 13 parts of silicon carbide, 6 parts of zirconium dioxide, 9 parts of potassium feldspar and 4 parts of lanthanum oxide were mixed to obtain a mixture B;

[0050] Under stirring conditions, the mixture B was added to the mixture A, the magnetic stirring speed was adjusted to 800 r / min, and stirring was carried out for 3 hours, followed by ultrasonic treatment, and the ultrasonic treatment frequency was 23 KHz, the ultrasonic treatment power was 25 W, and the ultrasonic treatment time was 15 minutes to obtain a nano high-temperature anti-oxidation coating. Example 2

[0051] A method for preparing a nano high-temperature anti-oxidation coating, comprising the following steps:

[0052] Water glass, 3-aminopropyltriethoxysilane and silicon dioxide in a mass ratio of 9:4:2 were mixed evenly, heated to 85°C, stirred at a speed of 1000 r / min for 1 hour, and naturally cooled to obtain a composite adhesive;

[0053] Boric acid and urea were added to a solvent (a mixture of water and methanol in a volume ratio of 1:1) and stirred to form a BN precursor sol. Alumina was then dispersed in the BN precursor sol and stirred at a stirring speed of 100 r / min for 60 minutes. After drying, a precursor / alumina composite was obtained. The composite was calcined at 1200°C in a nitrogen atmosphere to obtain boron nitride-coated alumina, wherein the mass ratio of the boric acid, urea, and alumina was 5:3:2.

[0054] 39 parts of composite adhesive, 7 parts of sodium carbonate, 2 parts of polyacrylate and 32 parts of water were added to a stirring kettle by weight, and stirred at a magnetic stirring speed of 500 r / min for 2 hours to obtain a mixture A;

[0055] Mixing 15 parts of boron nitride-coated alumina, 7 parts of modified diatomaceous earth, 11 parts of silicon carbide, 7 parts of zirconium dioxide, 9 parts of potassium feldspar, and 4 parts of lanthanum oxide in parts by weight to obtain a mixture B;

[0056] Under stirring conditions, the mixture B was added to the mixture A, the magnetic stirring speed was adjusted to 1000 r / min, and stirring was carried out for 3 hours, followed by ultrasonic treatment, and the frequency of the ultrasonic treatment was 23 KHz, the power of the ultrasonic treatment was 25 W, and the time of the ultrasonic treatment was 15 minutes to obtain a nano high-temperature anti-oxidation coating. Example 3

[0057] A method for preparing a nano high-temperature anti-oxidation coating, comprising the following steps:

[0058] Water glass, 3-aminopropyltriethoxysilane and silicon dioxide in a mass ratio of 8:3:2 were mixed uniformly, heated to 85°C, stirred at a speed of 800 r / min for 2 hours, and naturally cooled to obtain a composite adhesive;

[0059] Boric acid and urea were added to a solvent (a mixture of water and methanol in a volume ratio of 1:1) and stirred to form a BN precursor sol. Alumina was then dispersed in the BN precursor sol and stirred at a stirring speed of 100 r / min for 45 minutes. After drying, a precursor / alumina composite was obtained. The composite was calcined at 1200°C in a nitrogen atmosphere to obtain boron nitride-coated alumina, wherein the mass ratio of the boric acid, urea, and alumina was 6:5:2.

[0060] 38 parts of composite adhesive, 8 parts of sodium carbonate, 2 parts of polyacrylate and 35 parts of water were added to a stirring kettle according to weight ratio, and stirred at a magnetic stirring speed of 500 r / min for 1 hour to obtain a mixture A;

[0061] By weight, 13 parts of boron nitride-coated alumina, 9 parts of modified diatomaceous earth, 10 parts of silicon carbide, 7 parts of zirconium dioxide, 10 parts of potassium feldspar, and 3 parts of lanthanum oxide were mixed to obtain a mixture B;

[0062] Under stirring conditions, the mixture B was added to the mixture A, the magnetic stirring speed was adjusted to 800 r / min, and the mixture was stirred for 2 hours, followed by ultrasonic treatment with a frequency of 25 kHz, a power of 25 W, and a time of 15 minutes to obtain a nano high-temperature anti-oxidation coating.

[0063] Comparative Example 1:

[0064] Compared with Example 3, the adhesive in Comparative Example 1 is single water glass, and the rest is the same as Example 3.

[0065] Comparative Example 2:

[0066] Compared with Example 3, the adhesive in Comparative Example 2 does not contain 3-aminopropyltriethoxysilane, and the other components are the same as those in Example 3.

[0067] Comparative Example 3:

[0068] Compared with Example 3, silicon dioxide was not added to the adhesive in Comparative Example 3, and the rest was the same as in Example 3.

[0069] Comparative Example 4:

[0070] Compared with Example 3, in Comparative Example 4, a mixture of boron nitride and aluminum dioxide with a mass ratio of 5:2 is used instead of boron nitride to encapsulate aluminum dioxide, and the rest is the same as Example 3.

[0071] Comparative Example 5:

[0072] Compared with Example 5, no modified diatomaceous earth was added in Comparative Example 5, and the rest was the same as Example 3.

[0073] Comparative Example 6:

[0074] Compared with Example 3, no silicon carbide was added in Comparative Example 6, and the rest was the same as Example 3.

[0075] Comparative Example 7:

[0076] Compared with Example 3, no zirconium dioxide was added in Comparative Example 7, and the rest was the same as Example 3.

[0077] Comparative Example 8:

[0078] Compared with Example 3, in Comparative Example 8, potassium feldspar was not added, and the rest was the same as in Example 3.

[0079] Comparative Example 9:

[0080] Compared with Example 3, no lanthanum oxide was added in Comparative Example 9, and the other contents were the same as those in Example 3.

[0081] In order to further illustrate the effects brought about by the technical invention solution, the following effect verification results were performed.

[0082] 1: Verification of thermal shock resistance of coating

[0083] The specific method is as follows: the samples of the nano high-temperature anti-oxidation coating prepared in Examples 1 to 3 and the comparative samples of the coating prepared in Comparative Examples 1 to 9 are respectively coated or sprayed on the surface of a graphite rod with a diameter of 200 mm, dried at room temperature for 48 hours, and the same graphite rod is coated with the nano high-temperature anti-oxidation coating in sections, 1 / 2 of the section is coated with the nano high-temperature anti-oxidation coating, and 1 / 2 of the section is not coated with the nano high-temperature anti-oxidation coating, and then heated in a muffle furnace at 900°C for 7 hours. After being taken out of the high temperature, the coating is directly impacted with cold water to observe the changes in the coating. a. Observe whether the diameter of the coating area changes; b. After being taken out of the high temperature, the coating is directly impacted with cold water to observe whether there is any cracking or falling off. Evaluation criteria: No obvious change in the diameter of the coating area and no cracking or falling off of the coating indicate that the coating has good thermal shock resistance. The results are shown in Table 1 below.

[0084] Table 1: Thermal shock resistance

[0085]

[0086] Analysis of the data in Table 1 demonstrates that the coating of the present application protects graphene from oxidation and provides significant protection. The graphite diameter does not decrease significantly, and the coating exhibits no cracking or shedding, resulting in relatively stable application. However, the graphite diameters of Comparative Examples 1-9 decrease to varying degrees, suggesting an interaction between the components. The compounded components of the present coating provide superior thermal shock resistance.

[0087] 2. Antioxidant effect

[0088] Nano-high-temperature antioxidant coating samples from Examples 1-3 and comparative samples from Comparative Examples 1-9 were sprayed onto carbon anode surfaces. After spraying, the coatings were allowed to stand for 8 hours to complete curing and aging, dried at room temperature for 48 hours, and then placed in a high-temperature resistance furnace, heated to 900°C for 24 hours. The carbon weight loss rate and coating appearance were measured. A blank control was also established under the same conditions. Good antioxidant performance was evaluated by a final weight loss rate of ≤2% and the absence of cracking or delamination. The results are shown in Table 2 below.

[0089] Table 2: Antioxidant effect

[0090]

[0091] From the data analysis of Table 2, it can be seen that the present application optimizes the components and component ratios, and the oxidation weight loss rate at 900°C / 24h is less than 1%, which has excellent antioxidant properties and an excellent coating appearance. However, the changes in the component ratios in Comparative Examples 1 to 9 result in an oxidation weight loss rate higher than that of Example 3, indicating that the components of the present application have an interactive effect, which can help improve the overall antioxidant properties of the coating and thereby extend the service life of the carbon.

[0092] The above description of the embodiments is intended to facilitate understanding and application of the present invention by those skilled in the art. It is apparent that those skilled in the art can readily make various modifications to the embodiments and apply the general principles described herein to other embodiments without requiring creative effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A nano high temperature anti-oxidation coating for electrolytic aluminum anode carbon, characterized in that: The nano high temperature anti-oxidation coating comprises the following raw materials in parts by weight: 37 to 40 parts of composite binder, 12 to 15 parts of boron nitride coated alumina, 7 to 9 parts of modified diatomaceous earth, 10 to 13 parts of silicon carbide, 6 to 10 parts of zirconium dioxide, 9 to 10 parts of potassium feldspar, 3 to 5 parts of lanthanum oxide, 6 to 9 parts of dispersant, 1 to 2 parts of film-forming agent, and 30 to 50 parts of water; The composite adhesive is prepared from water glass, 3-aminopropyltriethoxysilane and silicon dioxide in a mass ratio of (7-9): (2-5): (1-2).

2. The nano high temperature anti-oxidation coating according to claim 1, characterized in that: The preparation method of the composite adhesive comprises the following steps: uniformly mixing water glass, 3-aminopropyltriethoxysilane and silicon dioxide, heating the mixture to 75° C. to 90° C., stirring the mixture at a speed of 500 r / min to 1000 r / min for 1 to 3 hours, and naturally cooling the mixture to obtain the composite adhesive.

3. The nano high temperature anti-oxidation coating according to claim 1, characterized in that: The preparation method of the boron nitride-coated aluminum dioxide comprises: adding boric acid and urea to a solvent, stirring uniformly to form a BN precursor sol, then dispersing aluminum dioxide in the BN precursor sol, stirring at a stirring speed of 50 rpm to 100 rpm for 30 to 60 minutes, and drying to obtain a precursor / aluminum dioxide composite. The aluminum dioxide coated with boron nitride is obtained by calcining the aluminum dioxide at 800°C to 1200°C in a nitrogen atmosphere.

4. The nano high temperature anti-oxidation coating according to claim 3, characterized in that: The solvent is a mixture of water and methanol in a volume ratio of 1:

1.

5. The nano high temperature anti-oxidation coating according to claim 3, characterized in that: The mass ratio of the boric acid, urea and aluminum dioxide is (1-7): (1-5): (1-3).

6. The nano high temperature anti-oxidation coating according to claim 1, characterized in that: The dispersant is at least one of sodium silicate, sodium carbonate, sodium stearate, polyacrylamide and sodium polyacrylate.

7. The nano high temperature anti-oxidation coating according to claim 1, characterized in that: The film-forming agent is at least one of polyurethane, polyacrylate and polyvinyl pyrrolidone.

8. A method for preparing a nanometer high-temperature anti-oxidation coating for electrolytic aluminum anode carbon, characterized in that: The preparation method is used to prepare the nano high-temperature anti-oxidation coating according to any one of claims 1 to 7, and the preparation method comprises the following steps: Add the composite binder, dispersant, film-forming agent and water into a stirring kettle, and stir at a magnetic stirring speed of 200 r / min to 500 r / min for 1 h to 2 h to obtain a mixture A; The boron nitride-coated aluminum dioxide, modified diatomaceous earth, silicon carbide, zirconium dioxide, potassium feldspar and lanthanum oxide are uniformly mixed to obtain a mixture B; Under stirring conditions, the mixture B is added to the mixture A, the speed of magnetic stirring is adjusted to 800 r / min to 1000 r / min, and stirring is carried out for 1 h to 3 h, followed by ultrasonic treatment to obtain a nano high-temperature anti-oxidation coating.

9. The preparation method according to claim 8, characterized in that The frequency of the ultrasonic treatment is 23KHz~26KHz, the power of the ultrasonic treatment is 25W~50W, and the time of the ultrasonic treatment is 15min~20min.

10. The preparation method according to claim 8, characterized in that The density of the nano high temperature anti-oxidation coating is 1.2 kg / m 3 ~1.5kg / m 3 .

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