Nano coating with high radiation heat exchange capacity and preparation method

Abstract

The invention discloses a nano coating with high radiation heat exchange capacity and a preparation method, which belongs to the field of nano coating technology. By weight, it is composed of: 10-15 parts of cordierite micropowder, 4-8 parts of ferric oxide, 5-10 parts of silicon carbide, 5-10 parts of chromium oxide, 3-8 parts of titanium dioxide, 5-10 parts of aluminum oxide, 1-5 parts of nickel oxide, 8-12 parts of homemade modified silica mixed suspension, 18-28 parts of composite binder, 0.4-1.2 parts of dispersant, 0.1-0.2 parts of defoamer, 0.3-0.5 parts of leveling agent, and 12-22 parts of deionized water. The technical solution of this application introduces a homemade modified silica mixed suspension into the nano coating. The sterically hindered imidazole rigid group introduced by the modified silica can reduce the mobility of each segment in the coating under high temperature conditions, thereby further improving the temperature resistance of the coating.

Description

Technical Field

[0001] The present invention belongs to the technical field of nano coatings, and in particular relates to a nano coating with high radiation heat exchange capability and a preparation method thereof. Background Art

[0002] High-temperature kilns are key equipment for industrial heating and are widely used in various industries. For example, high-temperature kilns are required in pillar industries of the national economy such as cement, power generation, glass, metallurgy, and chemicals.

[0003] High-temperature kilns are also energy-intensive. my country's approximately 120,000 existing high-temperature kilns consume at least 260 million tons of standard coal annually, accounting for 30% of my country's total energy consumption and 60% of industrial energy consumption. Energy conservation in my country's industrial high-temperature kilns is an urgent issue, and properly addressing this issue is crucial to accelerating the transformation of economic development. This also means there is significant room for improvement in energy conservation in industrial high-temperature kilns, and the research and development of energy-saving technologies will become a key area.

[0004] Among them, relevant energy-saving measures have also been developed for industrial high-temperature kilns, which are large energy consumers. These measures mainly revolve around the kiln's heating process, insulation process and waste heat utilization process.

[0005] Infrared radiation materials (also known as high-radiation materials) are new materials developed with the advancement of infrared radiation technology. They are a versatile new functional material, and with the rapid development of infrared technology, their industrial applications are becoming increasingly widespread. Leveraging the high heat absorption and emissivity of these special materials, they simultaneously absorb heat and emit a large amount of infrared radiation to the heated object. These materials can effectively utilize the heat from the furnace interior, returning it to the furnace interior, increasing the furnace's thermal efficiency. This not only saves energy but also effectively protects the furnace's interior and extends its service life.

[0006] There are generally two methods for using high-radiation materials: integral pressing and sintering molding and paint brushing. Among them, the integral pressing and sintering molding method cannot produce irregular, large-area integral products due to size limitations; while the paint brushing method has become the main application method for high-radiation materials because of its simple and convenient process and low cost.

[0007] Prior art includes, for example, Chinese invention patent application number CN202211689496.9, which discloses a nano coating with high radiation heat exchange capacity and a construction method. The construction method is specifically as follows: Step 1, caulking or polishing the surface of the object to be sprayed to make it as smooth as possible; Step 2, mixing the nano coating of the first aspect of the present invention in parts by weight, stirring evenly and then spraying; Step 3, raising the ambient temperature of the sprayed object in three stages;

[0008] The three-stage step-by-step heating includes raising the temperature to 200°C and maintaining it for 2 hours; then raising it to 500 degrees and maintaining it for 3 hours; and finally raising it to 850 degrees and maintaining it for 4 hours. Furthermore, in step 2, the spraying is performed 2 to 3 times.

[0009] Its defect is that the close bonding between the coating and the substrate is achieved through multiple spraying processes, and the temperature fluctuations in high-temperature kilns used for industrial heating are usually more severe. The coating that has been sprayed multiple times cannot remain stable in frequent thermal cycles, and it also has high requirements on the construction process. Multiple spraying operations will also affect the overall production efficiency and increase time costs.

[0010] The above-mentioned existing technologies do not improve the performance of the coating itself, and there is room for optimization and improvement in heat exchange capacity, thermal shock resistance, etc.

[0011] Therefore, there is an urgent need to introduce new process technologies to solve the above problems and seek more feasible solutions. Summary of the Invention

[0012] In order to solve the defects existing in the above technical solutions, the purpose of the present invention is to provide a nano-coating with high radiation heat exchange capacity and a preparation method; the purpose of the present invention can be achieved by the following technical solution: A nano-coating with high radiation heat exchange capacity, which is composed of the following parts by weight: 10-15 parts of cordierite micropowder, 4-8 parts of ferric oxide, 5-10 parts of silicon carbide, 5-10 parts of chromium oxide, 3-8 parts of titanium dioxide, 5-10 parts of aluminum oxide, 1-5 parts of nickel oxide, 8-12 parts of homemade modified silicon dioxide mixed suspension, 18-28 parts of composite binder, 0.4-1.2 parts of dispersant, 0.1-0.2 parts of defoaming agent, 0.3-0.5 parts of leveling agent, and 12-22 parts of deionized water.

[0013] The particle size of the cordierite powder is less than 5 μm;

[0014] The particle sizes of the ferric oxide and chromium oxide are both 50-150 nm;

[0015] The particle sizes of the silicon carbide, titanium dioxide, aluminum oxide, and nickel oxide are all between 100 and 500 nm;

[0016] The composite binder is a mixture obtained by uniformly mixing phosphate and high-temperature cement in a mass ratio of 1:1.

[0017] Furthermore, the phosphate is one of sodium phosphate and sodium dihydrogen phosphate;

[0018] Furthermore, the high-temperature mortar is of the brand YJF-2, which is purchased from Henan Sun Hung Kai Refractory Materials Co., Ltd.; the maximum operating temperature is 1500 degrees Celsius.

[0019] The method for preparing the homemade modified silica mixed suspension comprises the following steps: adding silica powder and N-imidazolepropyltrimethoxysilane to a 75% ethanol aqueous solution, and ultrasonically treating the solution for 2 hours to prepare N-imidazolepropyltrimethoxysilane-modified silica; centrifuging the suspension three times at 500 rpm, washing away unreacted N-imidazolepropyltrimethoxysilane with a 75% ethanol aqueous solution, collecting the N-imidazolepropyltrimethoxysilane-modified silica at the bottom of a centrifuge tube, and redispersing the solution in a 75% ethanol aqueous solution to prepare modified silica; and subsequently adding modified graphene oxide to the solution, stirring the solution and ultrasonically treating the solution for 4 hours to prepare a homemade modified silica mixed suspension bonded by hydrogen bonds.

[0020] The preparation of the modified graphene oxide comprises the following steps: taking graphene oxide, placing it in a 75% ethanol aqueous solution and fully dispersing it, then ultrasonically treating it for 2 hours, adding hexadecyltrimethoxysilane, and then continuously stirring and ultrasonically treating the mixed solution for 2 hours. The suspension is then centrifuged three times at a speed of 500 rpm, and unreacted hexadecyltrimethoxysilane is washed away with a 75% ethanol aqueous solution. Finally, the modified graphene oxide is collected as a solid mass at the bottom of the centrifuge tube, thereby completing the surface modification of the graphene oxide and preparing the modified graphene oxide.

[0021] A method for preparing a nano coating with high radiation heat exchange capacity comprises the following steps: adding cordierite micropowder to a composite binder, mechanically stirring for 30 minutes, and after uniform stirring, sequentially adding ferric oxide, silicon carbide, chromium oxide, titanium dioxide, aluminum oxide, nickel oxide, and modified silicon dioxide to preliminarily prepare a mixture A; subsequently, adding deionized water to the mixture A, mechanically stirring for 30-45 minutes, and finally sequentially adding a dispersant, a defoaming agent, and a leveling agent, and stirring evenly to prepare a nano coating with high radiation heat exchange capacity.

[0022] Furthermore, in specific applications, the nano-coating that has been stirred evenly can be ball-milled using a planetary ball mill at a ball milling speed of 600-800 r / min and a ball milling time of 1-2 h.

[0023] Furthermore, the dispersant is one of AFCONA-5009 and FLUIJET 1720; the dispersants are purchased from Shanghai Yuanhe Chemical Co., Ltd.;

[0024] Furthermore, the defoaming agent is a polyether defoaming agent TEGO Antifoam 3062; the defoaming agent is purchased from Evonik Digo Chemical Co., Ltd.;

[0025] Furthermore, the leveling agent is one or both of AFCONA-3085 and AFCONA-3587; the leveling agent is purchased from Efcona Polymer Co., Ltd.

[0026] Preparation of modified graphene oxide: 0.1 g of graphene oxide was taken and placed in 80 ml of 75% ethanol aqueous solution for full dispersion. After 2 hours of ultrasonic treatment, 0.8 g of hexadecyltrimethoxysilane was added, and the mixed solution was continuously stirred and ultrasonically treated for 2 hours. The suspension was then centrifuged three times at 500 rpm, and the unreacted hexadecyltrimethoxysilane was washed away with 75% ethanol aqueous solution. Finally, the modified graphene oxide was collected as a solid mass at the bottom of the centrifuge tube, thereby completing the surface modification of the graphene oxide and preparing modified graphene oxide.

[0027] A method for preparing a homemade modified silica mixed suspension is as follows: 30 g of silica powder and 2 g of N-imidazolepropyltrimethoxysilane are added to 80 ml of 75% ethanol aqueous solution and ultrasonically treated for 2 hours to prepare N-imidazolepropyltrimethoxysilane-modified silica; the suspension is centrifuged three times at 500 rpm, and the unreacted N-imidazolepropyltrimethoxysilane is washed away with 75% ethanol aqueous solution, the N-imidazolepropyltrimethoxysilane-modified silica is collected at the bottom of the centrifuge tube, and redispersed in 40 ml of 75% ethanol aqueous solution to prepare modified silica; then modified graphene oxide is added to the solution, and stirring and ultrasonic treatment are carried out for 4 hours to prepare a homemade modified silica mixed suspension bonded by hydrogen bonds.

[0028] Furthermore, the coating adopts a step-by-step sintering and curing process. After coating, the temperature is first raised to 100 degrees Celsius and maintained for 4 hours, then raised to 200 degrees Celsius and maintained for 2 hours; then raised to 600 degrees Celsius and maintained for 4 hours, and finally raised to 1000 degrees Celsius and maintained for 2 hours; finally, the coating is allowed to cool with the furnace, completing the sintering and curing, and completing the preparation of the coating.

[0029] The present invention has the beneficial effects:

[0030] 1. This application introduces a self-made modified silica mixed suspension into the nanocoating. The sterically hindered imidazole rigid groups introduced into the modified silica can reduce the mobility of each chain segment in the coating under high temperature environments, thereby further improving the heat resistance of the coating. In addition, the hexadecyltrimethoxysilane-modified graphene oxide with a long chain structure can improve the adhesion between the coating and the substrate, making it stable at high temperatures or in situations where the temperature fluctuates drastically, thereby having excellent thermal shock resistance.

[0031] 2. The self-made modified silica mixed suspension introduced in this application, when added to the coating, can not only improve the thermal stability and high temperature resistance of the coating, but also form a good chemical bond with the coating matrix, thereby significantly improving the adhesion to the substrate and improving the interfacial bonding performance, so that the coating of this application can be sprayed in one time, and at the same time, the surface structure of the cured coating can be denser and the mechanical properties can be better;

[0032] 3. The coating of the present application can be sprayed in one step when used in a high-temperature kiln, which is easier to use, greatly improves production efficiency, and reduces the time cost during application. DETAILED DESCRIPTION

[0033] 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 Examples. The illustrative embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention. In addition, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between the intermediate value within any stated value or stated range and any other stated value or intermediate value within the range is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0034] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0035] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be exemplary only.

[0036] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0037] The "parts" indicated in the following examples are all parts by weight.

[0038] Example 1

[0039] A nano coating with high radiation heat exchange capacity, comprising the following ingredients, by weight: 10 parts of cordierite micropowder, 4 parts of ferric oxide, 5 parts of silicon carbide, 5 parts of chromium oxide, 3 parts of titanium dioxide, 5 parts of aluminum oxide, 1 part of nickel oxide, 8 parts of a homemade modified silicon dioxide mixed suspension, 18 parts of a composite binder, 0.4 parts of a dispersant, 0.1 parts of a defoaming agent, 0.3 parts of a leveling agent, and 14 parts of deionized water;

[0040] The particle size of the cordierite powder is less than 5 μm;

[0041] The particle sizes of the ferric oxide and chromium oxide are both 50-150 nm;

[0042] The particle sizes of the silicon carbide, titanium dioxide, aluminum oxide, and nickel oxide are all between 100 and 500 nm;

[0043] The composite binder is a mixture of phosphate and high-temperature cement mixed in a mass ratio of 1:1;

[0044] The phosphate is sodium phosphate;

[0045] The high temperature mortar is of the brand YJF-2, purchased from Henan Sun Hung Kei Refractory Materials Co., Ltd.

[0046] The dispersant is AFCONA-5009;

[0047] The defoamer is polyether defoamer TEGO Antifoam 3062;

[0048] The leveling agent is AFCONA-3085.

[0049] A method for preparing a homemade modified silica mixed suspension is as follows: 30 g of silica powder and 2 g of N-imidazolepropyltrimethoxysilane are added to 80 ml of 75% ethanol aqueous solution and ultrasonically treated for 2 hours to prepare N-imidazolepropyltrimethoxysilane-modified silica; the suspension is centrifuged three times at 500 rpm, and the unreacted N-imidazolepropyltrimethoxysilane is washed away with 75% ethanol aqueous solution, the N-imidazolepropyltrimethoxysilane-modified silica is collected at the bottom of the centrifuge tube, and redispersed in 40 ml of 75% ethanol aqueous solution to prepare modified silica; then modified graphene oxide is added to the solution, and stirring and ultrasonic treatment are carried out for 4 hours to prepare a homemade modified silica mixed suspension bonded by hydrogen bonds.

[0050] Preparation of modified graphene oxide: 0.1 g of graphene oxide was taken and placed in 80 ml of 75% ethanol aqueous solution for full dispersion. After 2 hours of ultrasonic treatment, 0.8 g of hexadecyltrimethoxysilane was added, and the mixed solution was continuously stirred and ultrasonically treated for 2 hours. The suspension was then centrifuged three times at 500 rpm, and the unreacted hexadecyltrimethoxysilane was washed away with 75% ethanol aqueous solution. Finally, the modified graphene oxide was collected as a solid mass at the bottom of the centrifuge tube, thereby completing the surface modification of the graphene oxide and preparing modified graphene oxide.

[0051] A method for preparing a nano coating with high radiation heat exchange capacity comprises the following steps: adding cordierite micropowder to a composite binder, mechanically stirring for 30 minutes, and after uniform stirring, sequentially adding 4 parts of ferric oxide, 5 parts of silicon carbide, 5 parts of chromium oxide, 3 parts of titanium dioxide, 5 parts of aluminum oxide, 1 part of nickel oxide, and 8 parts of modified silicon dioxide to preliminarily prepare a mixture A; subsequently, adding deionized water to the mixture A, mechanically stirring for 30-45 minutes, and finally sequentially adding a dispersant, a defoaming agent, and a leveling agent, and stirring evenly to prepare a nano coating with high radiation heat exchange capacity.

[0052] In specific applications, the evenly stirred nano coating can be ball-milled using a planetary ball mill with a ball milling speed of 600-800 r / min and a ball milling time of 1-2 h.

[0053] Example 2

[0054] A nano coating with high radiation heat exchange capacity, comprising the following ingredients, by weight: 12 parts of cordierite micropowder, 5 parts of ferric oxide, 7 parts of silicon carbide, 6 parts of chromium oxide, 4 parts of titanium dioxide, 6 parts of aluminum oxide, 2 parts of nickel oxide, 9 parts of a homemade modified silicon dioxide mixed suspension, 20 parts of a composite binder, 0.6 parts of a dispersant, 0.1 parts of a defoaming agent, 0.4 parts of a leveling agent, and 14 parts of deionized water;

[0055] The composite binder is a mixture of phosphate and high-temperature cement mixed in a mass ratio of 1:1;

[0056] The phosphate is sodium dihydrogen phosphate;

[0057] The high temperature mortar is of the brand YJF-2, purchased from Henan Sun Hung Kei Refractory Materials Co., Ltd.

[0058] The dispersant is FLUIJET 1720;

[0059] The defoamer is polyether defoamer TEGO Antifoam 3062;

[0060] The leveling agent is AFCONA-3587;

[0061] In Example 2, the preparation method of the homemade modified silica mixed suspension and the preparation method of the nano-coating with high radiation heat exchange capacity are consistent with those in Example 1.

[0062] Example 3

[0063] A nano coating with high radiation heat exchange capacity, comprising the following ingredients, by weight: 14 parts of cordierite micropowder, 6 parts of ferric oxide, 8 parts of silicon carbide, 8 parts of chromium oxide, 6 parts of titanium dioxide, 8 parts of aluminum oxide, 4 parts of nickel oxide, 10 parts of a homemade modified silicon dioxide mixed suspension, 24 parts of a composite binder, 0.8 parts of a dispersant, 0.2 parts of a defoaming agent, 0.4 parts of a leveling agent, and 16 parts of deionized water;

[0064] The composite binder is a mixture of phosphate and high-temperature cement mixed in a mass ratio of 1:1;

[0065] The phosphate is sodium dihydrogen phosphate;

[0066] The high temperature mortar is of the brand YJF-2, purchased from Henan Sun Hung Kei Refractory Materials Co., Ltd.

[0067] The dispersant is AFCONA-5009;

[0068] The defoamer is polyether defoamer TEGO Antifoam 3062;

[0069] The leveling agent is AFCONA-3085;

[0070] In Example 3, the preparation method of the homemade modified silica mixed suspension and the preparation method of the nano-coating with high radiation heat exchange capacity are consistent with those in Example 1.

[0071] Example 4

[0072] A nano coating with high radiation heat exchange capacity, comprising the following ingredients, by weight: 14 parts of cordierite micropowder, 7 parts of ferric oxide, 9 parts of silicon carbide, 9 parts of chromium oxide, 7 parts of titanium dioxide, 9 parts of aluminum oxide, 4 parts of nickel oxide, 11 parts of a homemade modified silicon dioxide mixed suspension, 26 parts of a composite binder, 1 part of a dispersant, 0.2 parts of a defoaming agent, 0.5 parts of a leveling agent, and 19 parts of deionized water;

[0073] The composite binder is a mixture of phosphate and high-temperature cement mixed in a mass ratio of 1:1;

[0074] The phosphate is sodium phosphate;

[0075] The high temperature mortar is of the brand YJF-2, purchased from Henan Sun Hung Kei Refractory Materials Co., Ltd.

[0076] The dispersant is one of FLUIJET 1720;

[0077] The defoamer is polyether defoamer TEGO Antifoam 3062;

[0078] The leveling agent is AFCONA-3587;

[0079] In Example 4, the preparation method of the homemade modified silica mixed suspension and the preparation method of the nano-coating with high radiation heat exchange capacity are consistent with those in Example 1.

[0080] Example 5

[0081] A nano coating with high radiation heat exchange capacity, comprising the following ingredients, by weight: 15 parts of cordierite micropowder, 8 parts of ferric oxide, 10 parts of silicon carbide, 10 parts of chromium oxide, 8 parts of titanium dioxide, 10 parts of aluminum oxide, 5 parts of nickel oxide, 12 parts of a homemade modified silicon dioxide mixed suspension, 28 parts of a composite binder, 1.2 parts of a dispersant, 0.2 parts of a defoaming agent, 0.5 parts of a leveling agent, and 22 parts of deionized water;

[0082] The composite binder is a mixture of phosphate and high-temperature cement mixed in a mass ratio of 1:1;

[0083] The phosphate is sodium dihydrogen phosphate;

[0084] The high temperature mortar is of the brand YJF-2, purchased from Henan Sun Hung Kei Refractory Materials Co., Ltd.

[0085] The dispersant is FLUIJET 1720;

[0086] The defoamer is polyether defoamer TEGO Antifoam 3062;

[0087] The leveling agent is AFCONA-3587;

[0088] Among them, in Example 5, the preparation method of the homemade modified silica mixed suspension and the preparation method of the nano-coating with high radiation heat exchange capacity are consistent with those in Example 1.

[0089] Comparative Example 1

[0090] A nano coating with high radiation heat exchange capacity, comprising the following ingredients, by weight: 14 parts of cordierite micropowder, 6 parts of ferric oxide, 8 parts of silicon carbide, 8 parts of chromium oxide, 6 parts of titanium dioxide, 8 parts of aluminum oxide, 4 parts of nickel oxide, 10 parts of modified silicon dioxide, 24 parts of a composite binder, 0.8 parts of a dispersant, 0.2 parts of a defoaming agent, 0.4 parts of a leveling agent, and 16 parts of deionized water;

[0091] Preparation method of modified silica: 30 g of silica powder and 2 g of N-imidazolepropyltrimethoxysilane are added to 80 ml of 75% ethanol aqueous solution and ultrasonically treated for 2 hours to prepare N-imidazolepropyltrimethoxysilane-modified silica; the suspension is centrifuged three times at 500 rpm, and the unreacted N-imidazolepropyltrimethoxysilane is washed away with 75% ethanol aqueous solution, and the N-imidazolepropyltrimethoxysilane-modified silica is collected at the bottom of the centrifuge tube and redispersed in 40 ml of 75% ethanol aqueous solution to prepare the modified silica.

[0092] Among them, in Comparative Example 1, except that the preparation method of the modified silicon dioxide is different from that of Example 3, the remaining components and the preparation method of the nano-coating with high radiation heat exchange capacity are the same as those of Example 3.

[0093] Comparative Example 2

[0094] A nano coating with high radiation heat exchange capacity, comprising the following ingredients, calculated by weight: 14 parts of cordierite micropowder, 6 parts of ferric oxide, 8 parts of silicon carbide, 8 parts of chromium oxide, 6 parts of titanium dioxide, 8 parts of aluminum oxide, 4 parts of nickel oxide, 10 parts of a mixed suspension of silicon dioxide and graphene oxide, 24 parts of a composite binder, 0.8 parts of a dispersant, 0.2 parts of a defoaming agent, 0.4 parts of a leveling agent, and 16 parts of deionized water.

[0095] Preparation method of silica-graphene oxide mixed suspension: 30 g silica powder is added to 80 ml of 75% ethanol aqueous solution and ultrasonically treated for 2 hours, and then graphene oxide is added, and stirring and ultrasonic treatment are carried out for 4 hours to prepare a silica-graphene oxide mixed suspension.

[0096] In Comparative Example 2, silicon dioxide and graphene oxide were not chemically modified, and the remaining components and the preparation method of the nano-coating with high radiation heat transfer capacity were the same as those in Example 3.

[0097] Comparative Example 3

[0098] A nano coating with high radiation heat exchange capacity, comprising the following ingredients, by weight: 14 parts of cordierite micropowder, 6 parts of ferric oxide, 8 parts of silicon carbide, 8 parts of chromium oxide, 6 parts of titanium dioxide, 8 parts of aluminum oxide, 4 parts of nickel oxide, 10 parts of a mixed suspension of KH550 modified silicon dioxide, 24 parts of a composite binder, 0.8 parts of a dispersant, 0.2 parts of a defoaming agent, 0.4 parts of a leveling agent, and 16 parts of deionized water;

[0099] Preparation of modified graphene oxide: 0.1 g of graphene oxide was taken and placed in 80 ml of 75% ethanol aqueous solution for full dispersion. After 2 hours of ultrasonic treatment, 0.8 g of hexadecyltrimethoxysilane was added, and the mixed solution was continuously stirred and ultrasonically treated for 2 hours. The suspension was then centrifuged three times at 500 rpm, and the unreacted hexadecyltrimethoxysilane was washed away with 75% ethanol aqueous solution. Finally, the modified graphene oxide was collected as a solid mass at the bottom of the centrifuge tube, thereby completing the surface modification of the graphene oxide and preparing modified graphene oxide.

[0100] The preparation method of the homemade modified silica mixed suspension is as follows: 30g of silica powder and 2g of KH550 are added to 80ml of 75% ethanol aqueous solution and ultrasonically treated for 2h to prepare KH550-modified silica; the suspension is centrifuged three times at a speed of 500 rpm, and the unreacted KH550 is washed away with 75% ethanol aqueous solution, the KH550-modified silica is collected at the bottom of the centrifuge tube, and redispersed in 40ml of 75% ethanol aqueous solution to prepare modified silica; then modified graphene oxide is added to the solution, and stirring and ultrasonic treatment are carried out for 4h to prepare a KH550-modified silica mixed suspension.

[0101] Among them, in Comparative Example 3, except that the preparation method of the KH550 modified silica mixed suspension is different from that of Example 3, the remaining components and the preparation method of the nano-coating with high radiation heat exchange capacity are the same as those of Example 3.

[0102] Test example

[0103] During the test, Examples 1-5 and Comparative Examples 1-3 all adopted a step-by-step sintering and curing process. After coating, the temperature was first raised to 100 degrees Celsius and maintained for 4 hours, then raised to 200 degrees Celsius and maintained for 2 hours; then raised to 600 degrees Celsius and maintained for 4 hours, and finally raised to 1000 degrees Celsius and maintained for 2 hours; finally, the coating was allowed to cool with the furnace, that is, the sintering and curing were completed, and the preparation of the coating was completed; specifically, during the test, the thickness of the cured coating was controlled to be 1 mm.

[0104] Thermal shock resistance test: The protective coatings prepared from the high-radiative heat transfer nanocoatings prepared in Examples 1-5 and Comparative Examples 1-3 were placed in a high-temperature muffle furnace and heated to 1100°C. The mixture was held at this temperature for 10 minutes and then air-cooled to room temperature. This constituted one thermal cycle. The number of thermal cycles at which cracks began to appear in the coatings was recorded.

[0105] Emissivity test: In thermal equilibrium, the emissivity of the substrate after coating with protective coating is calculated using Kirchhoff's law;

[0106] Adhesion test: The protective coating adhesion test was completed with reference to the national standard GB / T 9286-2021 "Paint and Varnish Cross-cut Test". The test results are shown in Table 1 below:

[0107] Table 1

[0108]

[0109] Comprehensive performance analysis: The unmodified silicon dioxide and graphene oxide used in comparative example 2 are

[0110] Because silica and graphene oxide are inherently highly hydrophilic and have surface polarity, especially graphene oxide with carboxyl and hydroxyl groups on its surface, they easily aggregate and are difficult to disperse in the coating. Furthermore, their high surface energy makes them poorly compatible with other substrates in the coating, resulting in poor adhesion and thermal shock resistance. Comparative Example 1, which does not incorporate modified graphene oxide but only uses modified silica, lacks the long-chain modified graphene oxide. While its adhesion is inferior to that of Comparative Example 3, it is significantly better than that of Comparative Example 2.

[0111] Comparative Example 3 uses the commonly used KH550 modified silica. Although its adhesion is stronger than that of Comparative Example 2, it still has a certain gap with Examples 1-5. The possible reason is that the sterically hindered imidazole rigid group introduced by the modified silica in Examples 1-5 can reduce the mobility of each chain segment in the coating under high temperature environment, thereby improving the temperature resistance of the coating; and the homemade modified silica mixed suspension introduced in Examples 1-5, the two work together and are incorporated into the coating, which can not only improve the thermal stability and high temperature resistance of the coating, but also form good chemical bonds with the coating matrix, thereby significantly improving the adhesion to the substrate and improving the interfacial bonding performance. In addition, the hexadecyltrimethoxysilane-modified graphene oxide with a long chain structure can improve the adhesion between the coating and the substrate. Only the synergistic effect of the two can make the coating reach level 0 adhesion, so that it can remain stable at high temperatures or in situations where the temperature changes drastically, thereby having excellent thermal shock resistance.

[0112] The coating of the present application can be sprayed in one go when used in a high-temperature kiln, is easier to use, greatly improves production efficiency, and reduces the time cost of application. At the same time, the surface structure of the cured coating is denser and the mechanical properties are better.

[0113] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A nano coating with high radiation heat transfer capability, characterized in that: The composition is as follows, in parts by weight: 10-15 parts of cordierite micropowder, 4-8 parts of ferric oxide, 5-10 parts of silicon carbide, 5-10 parts of chromium oxide, 3-8 parts of titanium dioxide, 5-10 parts of aluminum oxide, 1-5 parts of nickel oxide, 8-12 parts of a homemade modified silicon dioxide mixed suspension, 18-28 parts of a composite binder, 0.4-1.2 parts of a dispersant, 0.1-0.2 parts of a defoaming agent, 0.3-0.5 parts of a leveling agent, and 12-22 parts of deionized water; The method for preparing the homemade modified silica mixed suspension comprises the following steps: adding silica powder and N-imidazolepropyltrimethoxysilane to a 75% ethanol aqueous solution, and ultrasonically treating the solution for 2 hours to prepare N-imidazolepropyltrimethoxysilane-modified silica; centrifuging the suspension three times at 500 rpm, washing away unreacted N-imidazolepropyltrimethoxysilane with a 75% ethanol aqueous solution, collecting the N-imidazolepropyltrimethoxysilane-modified silica at the bottom of a centrifuge tube, and redispersing the solution in a 75% ethanol aqueous solution to prepare modified silica; and subsequently adding modified graphene oxide to the solution, stirring the solution and ultrasonically treating the solution for 4 hours to prepare a homemade modified silica mixed suspension bonded by hydrogen bonds. The preparation method of the modified graphene oxide comprises the following steps: taking graphene oxide, placing it in a 75% ethanol aqueous solution and fully dispersing it, then ultrasonically treating it for 2 hours, adding hexadecyltrimethoxysilane, and then continuously stirring and ultrasonically treating the mixed solution for 2 hours. Then, the suspension is centrifuged three times at a speed of 500 rpm, and unreacted hexadecyltrimethoxysilane is washed away with a 75% ethanol aqueous solution. Finally, the modified graphene oxide is collected as a solid mass at the bottom of a centrifuge tube, thereby completing the surface modification of the graphene oxide and preparing the modified graphene oxide.

2. The nano coating with high radiation heat exchange capacity according to claim 1, characterized in that: The composition is as follows, in parts by weight, including: 14 parts of cordierite micropowder, 6 parts of ferric oxide, 8 parts of silicon carbide, 8 parts of chromium oxide, 6 parts of titanium dioxide, 8 parts of aluminum oxide, 4 parts of nickel oxide, 10 parts of homemade modified silicon dioxide mixed suspension, 24 parts of composite binder, 0.8 parts of dispersant, 0.2 parts of defoaming agent, 0.4 parts of leveling agent, and 16 parts of deionized water.

3. The nano coating with high radiation heat exchange capacity according to claim 1, characterized in that: The particle size of the cordierite powder is less than 5 μm.

4. The nano coating with high radiation heat exchange capacity according to claim 1, characterized in that: The particle sizes of the ferric oxide and chromium oxide are both between 50 and 150 nm.

5. The nano coating with high radiation heat exchange capacity according to claim 1, characterized in that: The particle sizes of the silicon carbide, titanium dioxide, aluminum oxide and nickel oxide are all between 100 and 500 nm.

6. The nano coating with high radiation heat exchange capacity according to claim 1, characterized in that: The composite binder is a mixture of phosphate and high-temperature cement mixed in a mass ratio of 1:1; The phosphate is one of sodium phosphate and sodium dihydrogen phosphate.

7. A nano coating with high radiation heat exchange capability according to any one of claims 1 to 6, characterized in that: The preparation method of the nano coating with high radiation heat exchange capacity comprises the following steps: adding cordierite powder to a composite binder, mechanically stirring for 30 minutes, and after uniform stirring, sequentially adding ferric oxide, silicon carbide, chromium oxide, titanium dioxide, aluminum oxide, nickel oxide, and modified silicon dioxide to preliminarily prepare a mixture A; then, adding deionized water to the mixture A, mechanically stirring for 30-45 minutes, and finally sequentially adding a dispersant, a defoaming agent, and a leveling agent, and stirring evenly to prepare the nano coating with high radiation heat exchange capacity.

8. The nano coating with high radiation heat exchange capacity according to claim 7, characterized in that: The method for preparing the nano coating with high radiation heat exchange capacity can be used to prepare the nano coating with high radiation heat exchange capacity using a planetary ball mill with a ball milling speed of 600-800 r / min and a ball milling time of 1-2 h.

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