A method for preparing a high-temperature kiln composite coating layer

Abstract

The present invention relates to the field of refractory materials, and in particular to a method for preparing a composite coating layer for a high-temperature kiln, comprising the following steps: S1, premixing: taking 9 parts by weight of EPDM and 6 parts by weight of nano-SiC for premixing; S2, mixing the EPDM and nano-SiC: uniformly mixing the EPDM and nano-SiC rubber mixture on a double-roll mill to form a 2mm thick film A; S3, using a layout machine to prepare CFRP (step length: 3.7mm, layout tension: 4-7N, layout speed: 22m / min); S4, placing the film A and CFRP layers in a frame mold, and using a flat vulcanizer to form and cure the composite coating layer of the film A and CFRP. The composite coating layer prepared by using the carbonized ablative material EPDM, the ablation-resistant filler SiC and the CFRP greatly improves the ablation resistance and bonding properties of the coating layer.

Description

Technical Field

[0001] The present invention relates to the field of refractory materials, and in particular to a method for preparing a composite coating layer for a high-temperature kiln. Background Art

[0002] High-temperature kilns have to withstand thermal loads in complex thermal environments, so it is necessary to select suitable thermal protection materials to make the kiln lining thin, light, and resistant to ablation, ensuring that the kiln can operate safely and reliably for a long time.

[0003] Today, as traditional energy sources are becoming increasingly depleted and new energy sources are developing slowly, the most urgent task is to develop lining materials that are lightweight, high-strength, have good thermal shock stability, high operating temperature, and can meet the needs of lightweight structure ultra-high temperature kilns for sustainable development.

[0004] The cladding layer is an important component of high-temperature kilns. It has the functions of insulation, buffering and limiting combustion. It can limit the combustion of the charge surface to control the combustion area of ​​the charge, prevent high-temperature gas from damaging the combustion chamber shell, and buffer the stress transfer between the furnace body and the charge. Therefore, a lightweight and ablation-resistant material is needed, which has good compatibility with a variety of shell composite materials. Since the overall size of the charge is subject to strict requirements, the combustion flow field will also become much more complicated, and the thermal protection material must withstand the thermal load in a complex thermal environment. Therefore, it is necessary to study the heat transfer and ablation characteristics of the cladding layer. According to the results of the heat transfer and ablation research, suitable thermal protection materials and appropriate thermal protection measures are selected to make the thermal protection lining material thin, light, and ablation-resistant, so as to ensure the safe and reliable operation of the high-temperature kiln for a long time.

[0005] There are four types of thermal protection systems: heat sink, radiation, sweat cooling, and ablation. Of these, ablation is the primary method for thermal protection, adapting to different thermal environments. The ablation mechanism sacrifices the mass of the material to absorb the heat from the airflow, achieving thermal protection. In practical applications, ablation-resistant fillers (such as silica, asbestos silica, carbon black, asbestos, graphite, potassium tantalum silica, and microspheres) are required to improve the thermal stability and ablation resistance of the coating. However, the addition of fillers can affect the mechanical properties of the coating material itself and the adhesion between the coating and the furnace body. Debonding at the interface can lead to side exposure of the charge to the environment, resulting in changes in the furnace's ballistic performance, fire, or detonation. Therefore, improvements are needed to the existing coating formulation system to enhance both ablation resistance and adhesion.

[0006] Therefore, how to propose a method to effectively improve the ablation resistance of the coating layer in material design while avoiding the occurrence of interface debonding is a key scientific problem that needs to be solved. It has important theoretical and engineering significance for improving the performance and safety and reliability of high-temperature kilns. Summary of the Invention

[0007] (1) Technical problems solved

[0008] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a method for preparing a composite coating layer for a high-temperature kiln, which solves the problems existing in the existing technology. The composite coating layer prepared by this method greatly reduces the thickness of the kiln lining layer, has excellent properties of light weight and ablation resistance, and at the same time avoids debonding at the interface, thereby ensuring the long-term safe and reliable operation of the kiln.

[0009] (2) Technical solution

[0010] To achieve the above-mentioned object, the present invention provides the following technical solution: A method for preparing a high-temperature kiln composite coating layer, characterized in that it comprises the following steps: S1. Premixing: taking 9 parts by weight of EPDM and 6 parts by weight of nano-SiC for premixing; S2. Mixing EPDM and nano-SiC: Mixing the EPDM and nano-SiC rubber mixture evenly on a double-roll mill to form a 2 mm thick film A; S3. Using a layout machine to prepare CFRP (step length: 3.7 mm, layout tension: 4-7 N, layout speed: 22 m / min); S4. After layering the film A and CFRP, place them in a frame mold, and use a flat vulcanizer to form and cure the film A and CFRP composite coating layer.

[0011] Preferably, the specific steps of pre-mixing in S1 are as follows: A. Divide 9 parts by weight of EPDM into 6 equal parts, each part is 1.5 parts by weight; B. Divide 6 parts by weight of nano-SiC into 6 equal parts, each part is 1 part by weight; C. Place 1.5 parts by weight of EPDM and 1 part by weight of nano-SiC into a first stirring mechanism and stir and mix them for 45 minutes. After stirring, introduce the mixture of EPDM and nano-SiC into a second stirring mechanism; D. Repeat step C 6 times until all the EPDM and nano-SiC are mixed and stirred; E. Start the second stirring mechanism to mix and stir the mixture therein for 60 minutes.

[0012] Preferably, in step C, after 1.5 parts by weight of EPDM and 1 part by weight of nano-SiC are stirred and mixed in a first stirring mechanism for 45 minutes, the mixture is introduced into an ultrasonic machine for ultrasonic vibration for 2-3 hours, and then the mixture after ultrasonic vibration is poured into a second stirring mechanism.

[0013] Preferably, 0.05 parts by weight of nano-graphite is added in step C, and the steps are as follows: 1.5 parts by weight of EPDM, 1 part by weight of nano-SiC and 0.05 parts by weight of nano-graphite are placed in a first stirring mechanism and stirred for 45 minutes. After stirring, the mixture of EPDM and nano-SiC is introduced into a second stirring mechanism.

[0014] Preferably, a powder sprayer is connected to the first stirring mechanism, and a powder spraying port of the powder sprayer is aligned with the EPDM in the first stirring mechanism.

[0015] Preferably, the step C includes the following steps: a. putting 1.5 parts by weight of EPDM into the first stirring mechanism and putting 1 part by weight of nano-SiC into the powder sprayer; b. starting the first stirring mechanism and the powder sprayer at the same time, stirring and spraying for 45 minutes; c. after stirring, introducing the mixture of EPDM and nano-SiC into the second stirring mechanism.

[0016] Preferably, the CFRP prepared in step S3 is processed, and the specific steps are as follows: 1) the prepared CFRP is immersed in a solution consisting of 15% acetone, 25% ethanol and 60% soft water for 2 hours; 2) the immersed CFRP is taken out and dried and baked; 3) the prepared CFRP is sintered at 500°C for 3 hours; 4) the sintered CFRP is naturally cooled to room temperature, and the cooled CFRP is infiltrated with resin glue so that the amount of glue on the CFRP is 2-3 kg / ㎡; 5) the CFRP coated with resin glue is dried.

[0017] Preferably, the rotation speed of the first stirring mechanism is 3000-4000 rpm, and the rotation speed of the second stirring mechanism is 4000-4500 rpm.

[0018] (3) Beneficial effects

[0019] 1. The present invention uses a composite coating layer prepared by using carbonized ablative material EPDM, ablative-resistant filler SiC and CFRP, which greatly improves the ablation resistance and bonding performance of the coating layer;

[0020] 2. The present invention stirs and mixes EPDM and nano-SiC in multiple steps, performs ultrasonic vibration after each stirring and mixing, and adds nano-SiC through a powder sprayer. This allows the nano-SiC to be evenly dispersed in the EPDM, thereby achieving filler uniformity and ultimately greatly improving the bonding strength. Interface debonding will not occur, thereby avoiding accidents such as changes in ballistic performance, fire or detonation in the kiln.

[0021] 3. The present invention greatly increases the dispersibility of SiC nanoparticles by adding nanographite to EPDM and nano-SiC, thereby greatly improving the internal adhesion;

[0022] 4. The present invention forms a porous structure in the CFRP by subjecting the CFRP made by the arrangement machine to processes such as impregnation, drying, sintering, and impregnation with resin glue, thereby greatly improving the amount of glue applied thereon and the firmness of the glue, laying a solid foundation for the subsequent vulcanization of the film A made of EPDM and nano-SiC and the CFRP, greatly increasing the effect of the later vulcanization, and ultimately greatly improving the performance of the composite coating layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The samples were prepared according to the embodiments of the present invention. DETAILED DESCRIPTION

[0024] The following is a combination of the embodiments of the present invention Figure 1 The technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0025] Example 1:

[0026] S1. Premixing: 54 kg of EPDM (EPDM is a flowable colloid) and 36 kg of nano-SiC (SiC is powdered) are premixed. The specific steps of premixing are as follows: A. Divide 54 kg of EPDM into 6 equal parts, each part is 9 kg; B. Divide 36 kg of nano-SiC into 6 equal parts, each part is 6 kg; C. Place 9 kg of EPDM and 6 kg of nano-SiC into a first stirring mechanism and stir and mix for 45 minutes. After stirring, introduce the mixture of EPDM and nano-SiC into a second stirring mechanism. Both the first stirring mechanism and the second stirring mechanism belong to the prior art. It consists of a stirring tank and a stirring rod, wherein the stirring rod is driven by a motor to rotate and stir. It is the most common stirring mechanism and will not be described in detail here. The speed of the first stirring mechanism is set to 3000 rpm and the speed of the second stirring mechanism is set to 4000 rpm. D. Repeat step C 6 times until all the EPDM and nano-SiC are mixed and stirred. E. Start the second stirring mechanism to mix and stir the mixture for 60 minutes. The pre-mixing process is carried out in a room at a room temperature of 25°C and a humidity of 10%. The EPDM is selected after comparing the ablation and mechanical properties of the coating material. The specific data is shown in the table below:

[0027] Performance comparison of coating materials

[0028]

[0029] S2. Mixing EPDM and nano-SiC: The EPDM and nano-SiC mixed rubber mixture stirred in step S1 is evenly mixed on a two-roll mill (wherein the two-roll mill belongs to the prior art) to form a 2 mm thick film A. As long as the thickness of the film A is ensured to be 2 mm, the length and width can be set as needed;

[0030] S3. Prepare CFRP using a layout machine (step length: 3.7 mm, layout tension: 4-7 N, layout speed: 22 m / min). Prepare carbon fiber reinforced composite material CFRP by the layout machine so that the length and width of the prepared CFRP are equal to or slightly larger than the length and width of film A. Then, the prepared CFRP is processed as follows: 1) Immerse the prepared CFRP in a solution consisting of 15% acetone, 25% ethanol and 60% soft water for 2 hours; 2) Take out the impregnated CFRP and dry it in an oven; 3) Sinter the prepared CFRP at 500°C for 3 hours; 4) Cool the sintered CFRP naturally to room temperature, and soak the cooled CFRP in resin glue so that the amount of glue applied on the CFRP is 2 kg / m2; 5) Dry the CFRP coated with the resin glue;

[0031] S4. After the film A and CFRP are layered, they are placed in a frame mold, and a flat-plate vulcanizer is used to form and cure the composite coating of the film A and CFRP. The vulcanization by the flat-plate vulcanizer belongs to the existing technology and will not be described in detail here.

[0032] Example 2:

[0033] S1. Premixing: 90 kg of EPDM (EPDM is a flowable colloid) and 60 kg of nano-SiC (SiC is in powder form) are premixed. The specific steps of premixing are as follows: A. Divide 90 kg of EPDM into 6 equal parts, each part is 15 kg; B. Divide 60 kg of nano-SiC into 6 equal parts, each part is 10 kg; C. Place 15 kg of EPDM and 10 kg of nano-SiC into a first stirring mechanism and stir and mix for 45 minutes. After stirring, introduce the mixture of EPDM and nano-SiC into a second stirring mechanism. Both the first stirring mechanism and the second stirring mechanism belong to the prior art and are composed of a stirring tank and a stirring rod. , wherein the stirring rod is driven by a motor to rotate and stir, which is the most common stirring mechanism and will not be described in detail here. The speed of the first stirring mechanism is set to 3000 rpm, and the speed of the second stirring mechanism is set to 4000 rpm. Then, the stirred and mixed mixture of EPDM and nano-SiC is introduced into an ultrasonic machine for ultrasonic oscillation for 2.5 hours, and then the mixture after ultrasonic oscillation is poured into the second stirring mechanism; D. Repeat step C 6 times until all the EPDM and nano-SiC are mixed and stirred; E. Start the second stirring mechanism to mix and stir the mixture therein for 60 minutes. The pre-mixing process is carried out indoors at a room temperature of 25°C and a humidity of 10%.

[0034] S2. Mixing EPDM and nano-SiC: The EPDM and nano-SiC mixed rubber mixture stirred in step S1 is evenly mixed on a two-roll mill (wherein the two-roll mill belongs to the prior art) to form a 2 mm thick film A. As long as the thickness of the film A is ensured to be 2 mm, the length and width can be set as needed;

[0035] S3. Prepare CFRP using a layout machine (step length: 3.7 mm, layout tension: 4-7 N, layout speed: 22 m / min). Prepare carbon fiber reinforced composite material CFRP by the layout machine so that the length and width of the prepared CFRP are equal to or slightly larger than the length and width of film A. Then, the prepared CFRP is processed as follows: 1) Immerse the prepared CFRP in a solution consisting of 15% acetone, 25% ethanol and 60% soft water for 2 hours; 2) Take out the impregnated CFRP and dry it in the air and bake it in a oven; 3) Sinter the prepared CFRP at 500°C for 3 hours; 4) Cool the sintered CFRP naturally to room temperature, and soak the cooled CFRP in resin glue so that the amount of glue applied on the CFRP is 3 kg / m2; 5) Dry the CFRP coated with the resin glue;

[0036] S4. After the film A and CFRP are layered, they are placed in a frame mold, and a flat-plate vulcanizer is used to form and cure the composite coating of the film A and CFRP. The vulcanization by the flat-plate vulcanizer belongs to the existing technology and will not be described in detail here.

[0037] Example 3:

[0038] S1. Premixing: Take 72kg of EPDM (EPDM is a flowable colloid) and 48kg of nano-SiC (SiC is powdered) for premixing. The specific steps of premixing are as follows: A. Divide 72kg of EPDM into 6 equal parts, each part is 12kg; B. Divide 48kg of nano-SiC into 6 equal parts, each part is 8kg; C. Put 12kg of EPDM into the first stirring mechanism and put 8kg of nano-SiC into the powder sprayer. Start the first stirring mechanism and the powder sprayer at the same time, stirring and spraying for 45 minutes. After the stirring is completed, mix EPDM and nano-SiC. iC mixture is introduced into the second stirring mechanism, wherein the first stirring mechanism and the second stirring mechanism are both of the prior art, consisting of a stirring tank and a stirring rod, wherein the stirring rod is driven by a motor to rotate and stir, which is the most conventional stirring mechanism and is not described in detail here. The speed of the first stirring mechanism is set to 3500 rpm and the speed of the second stirring mechanism is set to 4500 rpm; D. Repeat step C 6 times until all the EPDM and nano-SiC are mixed and stirred; E. Start the second stirring mechanism to mix and stir the mixture therein for 60 minutes. The pre-mixing process is carried out indoors at a room temperature of 25°C and a humidity of 10%.

[0039] S2. Mixing EPDM and nano-SiC: The EPDM and nano-SiC mixed rubber mixture stirred in step S1 is evenly mixed on a two-roll mill (wherein the two-roll mill belongs to the prior art) to form a 2 mm thick film A. As long as the thickness of the film A is ensured to be 2 mm, the length and width can be set as needed;

[0040] S3. Prepare CFRP using a layout machine (step length: 3.7 mm, layout tension: 4-7 N, layout speed: 22 m / min). Prepare carbon fiber reinforced composite material CFRP by the layout machine so that the length and width of the prepared CFRP are equal to or slightly larger than the length and width of film A. Then, the prepared CFRP is processed as follows: 1) Immerse the prepared CFRP in a solution consisting of 15% acetone, 25% ethanol and 60% soft water for 2 hours; 2) Take out the impregnated CFRP and dry it in an oven; 3) Sinter the prepared CFRP at 500°C for 3 hours; 4) Cool the sintered CFRP naturally to room temperature, and soak the cooled CFRP in resin glue so that the amount of glue applied on the CFRP is 2 kg / m2; 5) Dry the CFRP coated with the resin glue;

[0041] S4. After the film A and CFRP are layered, they are placed in a frame mold, and a flat-plate vulcanizer is used to form and cure the composite coating of the film A and CFRP. The vulcanization by the flat-plate vulcanizer belongs to the existing technology and will not be described in detail here.

[0042] Example 4

[0043] S1. Premixing: 108 kg of EPDM (EPDM is a flowable colloid) and 72 kg of nano-SiC (SiC is powdered) are premixed. The specific steps of premixing are as follows: A. Divide 108 kg of EPDM into 6 equal parts, each part is 18 kg; B. Divide 72 kg of nano-SiC into 6 equal parts, each part is 12 kg; C. Put 18 kg of EPDM into the first stirring mechanism, put 12 kg of nano-SiC and 0.6 kg of nano-graphite into the powder sprayer, start the first stirring mechanism and the powder sprayer at the same time, stir and spray for 45 minutes, and after stirring is completed, The mixture of EPDM and nano-SiC is introduced into the second stirring mechanism, wherein the first stirring mechanism and the second stirring mechanism are both prior art, consisting of a stirring tank and a stirring rod, wherein the stirring rod is driven by a motor to rotate and stir, which is the most conventional stirring mechanism and will not be described in detail here. The speed of the first stirring mechanism is set to 3500 rpm and the speed of the second stirring mechanism is set to 4500 rpm; D. Repeat step C 6 times until all the EPDM and nano-SiC are mixed and stirred; E. Start the second stirring mechanism to mix and stir the mixture therein for 60 minutes. The pre-mixing process is carried out indoors at a room temperature of 25°C and a humidity of 10%.

[0044] S2. Mixing EPDM and nano-SiC: The EPDM and nano-SiC mixed rubber mixture stirred in step S1 is evenly mixed on a two-roll mill (wherein the two-roll mill belongs to the prior art) to form a 2 mm thick film A. As long as the thickness of the film A is ensured to be 2 mm, the length and width can be set as needed;

[0045] S3. Prepare CFRP using a layout machine (step length: 3.7 mm, layout tension: 4-7 N, layout speed: 22 m / min). Prepare carbon fiber reinforced composite material CFRP by the layout machine so that the length and width of the prepared CFRP are equal to or slightly larger than the length and width of film A. Then, the prepared CFRP is processed as follows: 1) Immerse the prepared CFRP in a solution consisting of 15% acetone, 25% ethanol and 60% soft water for 2 hours; 2) Take out the impregnated CFRP and dry it in an oven; 3) Sinter the prepared CFRP at 500°C for 3 hours; 4) Cool the sintered CFRP naturally to room temperature, and soak the cooled CFRP in resin glue so that the amount of glue applied on the CFRP is 2 kg / m2; 5) Dry the CFRP coated with the resin glue;

[0046] S4. After the film A and CFRP are layered, they are placed in a frame mold, and a flat-plate vulcanizer is used to form and cure the composite coating of the film A and CFRP. The vulcanization by the flat-plate vulcanizer belongs to the existing technology and will not be described in detail here.

[0047] Comparative Example 1

[0048] S1. Premixing: 54 kg of epoxy resin EP (EP is a flowable colloid) and 36 kg of silicon dioxide (silicon dioxide is powdered) are premixed. The premixing is carried out by a stirring mechanism. The premixing process is carried out indoors at a room temperature of 25°C and a humidity of 10%.

[0049] S2. Mixing EP and silica: The EP and silica mixture mixed in step S1 is mixed evenly on a two-roll mill (wherein the two-roll mill belongs to the prior art) to form a 2 mm thick film A. As long as the thickness of the film A is 2 mm, the length and width can be adjusted as needed.

[0050] S3. Prepare CFRP using a layout machine (step length: 3.7 mm, layout tension: 4-7 N, layout speed: 22 m / min). Prepare carbon fiber reinforced composite material CFRP using the layout machine so that the length and width of the prepared CFRP are equal to or slightly larger than the length and width of film A;

[0051] S4. After the film A and CFRP are layered, they are placed in a frame mold, and a flat-plate vulcanizer is used to form and cure the composite coating of the film A and CFRP. The vulcanization by the flat-plate vulcanizer belongs to the existing technology and will not be described in detail here.

[0052] The above examples and comparative examples were used to analyze the tear-off adhesion strength, tensile strength TS, elongation E, and linear ablation rate. (The tear-off adhesion strength was measured according to QJ2038.1A-2004, the tensile strength TS and elongation E were measured according to the national standard GB / T 528-1998, and the linear ablation rate was measured according to the national standard GJB 323A-1996. Test pieces of different modified coating / propellant bonding were prepared, and the tear-off test and double cantilever beam test were used to characterize the coating interface adhesion performance and analyze the interface performance damage mechanism.) Specific experimental data are shown in the following table:

[0053]

[0054] In summary, the bonding performance and ablation resistance of the composite coating prepared by the present invention are greatly improved.

[0055] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a high-temperature kiln composite coating layer, characterized in that: The following steps are involved: S1. Premixing: 9 parts by weight of EPDM and 6 parts by weight of nano-SiC are premixed; S2. Mixing EPDM and nano-SiC: Mix the EPDM and nano-SiC rubber mixture evenly on a two-roll mill to form a 2 mm thick film A; S3, preparing CFRP using a layout machine; S4, placing the film A and CFRP layers in a frame mold, and using a flat vulcanizing machine to form and cure the composite coating of film A and CFRP; Among them, the further processing steps for CFRP in step S3 are as follows: 1) The prepared CFRP was immersed in a solution consisting of 15% acetone, 25% ethanol and 60% soft water for 2 hours; 2) Take out the impregnated CFRP and dry it in the oven; 3) Sintering the prepared CFRP at 500°C for 3h; 4) Allow the sintered CFRP to cool naturally to room temperature, and then soak the cooled CFRP in resin glue to ensure that the amount of glue applied on the CFRP is 2-3 kg / ㎡; 5) Allow the CFRP coated with resin glue to dry.

2. The method for preparing a high-temperature kiln composite coating according to claim 1, characterized in that: The specific steps of premixing in S1 are as follows: A. Divide 9 parts by weight of EPDM into 6 equal parts, each part is 1.5 parts by weight; B. Divide 6 parts by weight of nano-SiC into 6 equal parts, each part is 1 part by weight; C. Place 1.5 parts by weight of EPDM and 1 part by weight of nano-SiC into a first stirring mechanism and stir and mix for 45 minutes. After stirring, pour the mixture of EPDM and nano-SiC into a second stirring mechanism; D. Repeat step C 6 times until all the EPDM and nano-SiC are mixed and stirred; E. Start the second stirring mechanism to mix and stir the mixture for 60 minutes.

3. The method for preparing a high-temperature kiln composite coating layer according to claim 2, characterized in that: In step C, 1.5 parts by weight of EPDM and 1 part by weight of nano-SiC are stirred and mixed in a first stirring mechanism for 45 minutes, and then the mixture is poured into an ultrasonic machine for ultrasonic vibration for 2-3 hours, and then the mixture after ultrasonic vibration is poured into a second stirring mechanism.

4. The method for preparing a high-temperature kiln composite coating layer according to claim 2, characterized in that: In step C, 0.05 parts by weight of nano-graphite is added, and the steps are as follows: 1.5 parts by weight of EPDM, 1 part by weight of nano-SiC and 0.05 parts by weight of nano-graphite are placed in a first stirring mechanism and stirred for 45 minutes. After stirring, the mixture of EPDM, nano-SiC and nano-graphite is poured into a second stirring mechanism.

5. The method for preparing a high-temperature kiln composite coating layer according to claim 2, characterized in that: The first stirring mechanism is connected to a powder sprayer, and a powder spraying port of the powder sprayer is aligned with the EPDM in the first stirring mechanism.

6. The method for preparing a high-temperature kiln composite coating layer according to claim 5, characterized in that: The step C comprises the following steps: a. Place 1.5 parts by weight of EPDM into the first stirring mechanism and 1 part by weight of nano-SiC into the powder sprayer; b. Start the first stirring mechanism and the powder sprayer at the same time, stirring and spraying for 45 minutes; c. After stirring is completed, pour the mixture of EPDM and nano-SiC into the second stirring mechanism.

7. The method for preparing a high-temperature kiln composite coating layer according to claim 2, characterized in that: The rotation speed of the first stirring mechanism is 3000-4000 rpm, and the rotation speed of the second stirring mechanism is 4000-4500 rpm.

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