CuO-based heat absorption coating as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of coating materials, and particularly relates to a CuO-based heat absorption coating as well as a preparation method and application thereof. The modified copper oxide is prepared by doping cobalt and synergistically preparing graphene oxide, the heat absorption coating is prepared by using the modified copper oxide in cooperation with the spinel material and the compound binder, and the effective wave band average absorptivity and the solar energy absorption efficiency of the coating are effectively improved by means of the combined action of multiple components.

Description

Technical Field

[0001] The present invention belongs to the technical field of coating materials, and specifically relates to a CuO-based heat-absorbing coating, its preparation method and application. Background Art

[0002] A selective absorption coating is a functional material that can efficiently absorb solar radiation while suppressing heat radiation loss. This coating can fully absorb the energy of sunlight, while reducing the heat radiation loss caused by the increase in temperature of the heat-absorbing plate, greatly improving the solar energy utilization rate, and is widely used in solar collectors, solar thermal power generation, building energy conservation and other fields. The selective absorption coating is required to have a low reflectivity to the waves in the ultraviolet-visible-near-infrared spectrum and a high reflectivity to the waves in the far-infrared spectrum, that is, to achieve a large absorption in the spectral range where solar energy is concentrated, while reducing the emission of the absorbed wavelength.

[0003] Chinese Patent (Publication No. CN115627458A) discloses a Cu-Fe-based spinel / CuO composite coating, its preparation method and application. The main steps of this preparation method are: (1) pretreatment of the substrate; (2) preparation and coating of Cu-Fe sol; (3) heat treatment to obtain a Cu-Fe-based spinel layer; (4) preparation and coating of Cu sol; (5) heat treatment to obtain a Cu-Fe-based spinel layer / CuO layer. This invention has the characteristics of simple operation process, controllable composition and thickness of the composite coating, and being suitable for substrates with complex shapes. The prepared Cu-Fe-based spinel / CuO composite coating is relatively tightly bonded to the substrate, and the elements in the spinel layer are evenly distributed. At the same time, it is proposed that this composite coating is suitable for providing protection for the alloy connector of a solid oxide fuel cell (SOFC) and can be used as a coating for the SOFC alloy connector. The composite coating of this patented technology has a double-layer structure containing a spinel layer and a CuO layer, and there is still a lack of research on how to combine spinel materials with CuO materials to form a single-layer coating and improve the average absorption rate in the effective band and the solar energy absorption efficiency.

[0004] Therefore, there is an urgent need for a CuO-based heat-absorbing coating, which can improve the average absorption rate in the effective band and the solar energy absorption efficiency of the coating by modifying CuO, adding spinel materials, and selecting a suitable compound binder, with the joint action of multiple components. Summary of the Invention

[0005] The object of the present invention is to provide a CuO-based heat-absorbing coating, which is prepared by doping cobalt and synergistically preparing graphene oxide to obtain modified copper oxide, and cooperating with the use of spinel materials and compound binders, so as to effectively improve the average absorption rate in the effective band and the solar energy absorption efficiency of the coating with the joint action of multiple components.

[0006] To achieve the above object, the present invention provides the following technical solutions: The first aspect of the present invention provides a heat-absorbing coating based on CuO. By weight, the coating comprises the following components: 20 - 30 parts of modified copper oxide, 10 - 15 parts of spinel material, 50 - 60 parts of binder, 0.8 - 1.2 parts of dispersant, 0.8 - 1.2 parts of defoamer, and 0.8 - 1.2 parts of leveling agent.

[0007] As a preferred embodiment, the weight parts of the modified copper oxide in the present invention can be 20 parts, 22 parts, 24 parts, 26 parts, 28 parts, 30 parts, etc.

[0008] As a preferred embodiment, the weight parts of the spinel material in the present invention can be 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, etc.

[0009] As a preferred embodiment, the weight parts of the binder in the present invention can be 50 parts, 52 parts, 54 parts, 56 parts, 58 parts, 60 parts, etc.

[0010] As a preferred embodiment, the weight parts of the dispersant in the present invention can be 0.8 parts, 0.9 parts, 1.0 parts, 1.1 parts, 1.2 parts, etc.

[0011] As a preferred embodiment, the weight parts of the defoamer in the present invention can be 0.8 parts, 0.9 parts, 1.0 parts, 1.1 parts, 1.2 parts, etc.

[0012] As a preferred embodiment, the weight parts of the leveling agent in the present invention can be 0.8 parts, 0.9 parts, 1.0 parts, 1.1 parts, 1.2 parts, etc.

[0013] As a preferred embodiment, the preparation method of the modified copper oxide comprises: by weight, adding 16 - 20 parts of copper nitrate and 2 - 4 parts of cobalt chloride into 240 - 260 parts of deionized water to dissolve fully, heating to 70 - 80 °C, then successively adding 40 - 50 parts of 1 - 2 mol / L sodium hydroxide aqueous solution and 2 - 4 parts of 0.1 - 0.2 g / ml sodium citrate aqueous solution for heat treatment, adding 2 - 4 parts of graphene oxide for hydrothermal reaction, and obtaining the modified copper oxide after calcination treatment.

[0014] As a preferred embodiment, the conditions of the heat treatment include: controlling the temperature at 96 - 100 °C for constant temperature reaction for 10 - 20 min.

[0015] As a preferred embodiment, the steps of the hydrothermal reaction include: first, ultrasonic dispersion for 6 - 10 min, transferring to a reaction kettle, controlling the temperature at 170 - 180 °C for hydrothermal reaction for 2 - 4 h, cooling to room temperature, washing with water, and drying.

[0016] As a preferred embodiment, the steps of the calcination treatment include: transferring to a muffle furnace, heating up to 340 - 360 °C at a rate of 4 - 6 °C / min for calcination for 100 - 120 min, and cooling with the furnace.

[0017] The modified copper oxide of the present invention regulates the energy band structure, enhances the separation efficiency of photo-generated carriers, and optimizes the optical absorption characteristics through the doping of cobalt. And due to the formation of a nano-porous structure by doping, the direct reflection of light is reduced through diffuse reflection, significantly improving the average absorption rate of the effective band and the solar absorption efficiency of the coating. In addition, the sheet network of graphene oxide in the modified copper oxide can form a three-dimensional framework, maintaining the porous structure and enhancing the interaction between light and the material, thus improving the absorption efficiency.

[0018] As a preferred embodiment, the spinel material is nano-magnesium chromite spinel and carbon nanotube-modified lithium nickel manganese oxide spinel.

[0019] As a preferred embodiment, the mass ratio of nano-magnesium chromite spinel to carbon nanotube-modified lithium nickel manganese oxide spinel in the spinel material is (1 - 2):1.

[0020] The present invention selects nano-magnesium chromite spinel and carbon nanotube-modified lithium nickel manganese oxide spinel as the spinel material combination. The nano-scale particles of nano-magnesium chromite spinel can form a porous or rough surface, increasing the number of reflections and the path of light in the coating; at the same time, the chromium ions in magnesium chromite spinel can generate dielectric loss through electron transition, enhancing the light-matter interaction, and enhancing light absorption by means of plasma resonance or non-radiative recombination, thereby improving the average absorption rate of the effective band and the solar absorption efficiency. The carbon nanotube-modified lithium nickel manganese oxide spinel has surface porosity. By utilizing the different reflection effects of the microporous rough surface on spectra of different wavelengths, the morphology and structure of the coating surface are controlled, making its microscopic surface honeycomb-shaped and the size of the microporous rough surface close to the peak value of the visible light spectrum, thus playing a trapping role on solar radiation and increasing the average absorption rate of the effective band and the solar absorption efficiency.

[0021] As a preferred embodiment, the binder is sodium silicate and tetraethyl orthosilicate.

[0022] As a preferred embodiment, the mass ratio of sodium silicate to tetraethyl orthosilicate in the binder is (1 - 2):1.

[0023] In the present invention, sodium silicate and tetraethyl orthosilicate are selected as the compound binder. As a good inorganic binder, sodium silicate can combine with various substrates (such as metals, ceramics) to form a coating structure, and dehydrate at high temperatures to form a temperature-resistant network structure, ensuring the structural stability of the coating in a high-temperature environment; tetraethyl orthosilicate can generate nano-scale silica particles through hydrolysis and polycondensation reactions, forming a porous or mesoporous structure, enhancing light scattering and absorption; through the synergistic effect of sodium silicate and tetraethyl orthosilicate, sodium silicate provides macroscopic adhesion and a high-temperature-resistant skeleton, and tetraethyl orthosilicate fills the microscopic pores and optimizes the surface roughness, forming a multi-level structure to reduce light reflection, increase the average absorption rate in the effective band, and improve the solar absorption efficiency.

[0024] As a preferred embodiment, the dispersant is selected from one or more of Mel Chemical HY-2600, Mel Chemical HY-168, and Degussa Dispers-760W.

[0025] As a preferred embodiment, the defoamer is selected from one or more of Mel Chemical HY-1042, Degussa Tego825, and Degussa Airex-902W.

[0026] As a preferred embodiment, the leveling agent is selected from Efka AFCONA-3587 or Mel Chemical HY-5030.

[0027] The second aspect of the present invention provides a method for preparing a CuO-based endothermic coating as described in the first aspect, comprising the following steps: S1: Sandblast the surface of the substrate to obtain a pretreated substrate; S2: By weight, add 0.8-1.2 parts of dispersant, 0.8-1.2 parts of defoamer, and 0.8-1.2 parts of leveling agent to 50-60 parts of binder, stir well, then add 20-30 parts of modified copper oxide and 10-15 parts of spinel material, disperse them uniformly at high speed to obtain a mixture, transfer the mixture to a ball mill for ball milling to obtain a coating; S3: Spray the coating on the surface of the pretreated substrate, let it stand overnight, and then carry out a curing treatment to obtain a CuO-based endothermic coating.

[0028] As a preferred embodiment, the conditions for the ball milling treatment include: a rotation speed of 300-400 rpm and a time of 3-5 h.

[0029] As a preferred embodiment, the steps of the curing treatment include: first curing at room temperature for 20-24 h, and then heating to 480-500 °C and curing for 6-8 h.

[0030] The third aspect of the present invention provides an application of the CuO-based endothermic coating as described in the first aspect in an endothermic device.

[0031] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: 1. The graphene oxide introduced by the modified copper oxide of the present invention can form a conjugated system with the carbon nanotubes modified by carbon nanotubes on the surface of nickel manganese lithium spinel. The two-dimensional sheet layer of graphene oxide and the one-dimensional tubular structure of carbon nanotubes form a porous network, which extends the propagation path of light in the coating through multiple scattering and diffuse reflection, reduces direct light reflection, and at the same time, the nanoscale rough surface of the composite material further enhances light scattering, improving the average absorption rate of the effective band and the solar energy absorption efficiency of the coating.

[0032] 2. The modified copper oxide of the present invention regulates the energy band structure, enhances the separation efficiency of photo-generated carriers and optimizes the optical absorption characteristics by doping with cobalt. At the same time, the sheet network of the introduced graphene oxide can form a three-dimensional skeleton, maintaining the porous structure and enhancing the interaction between light and the material, improving the absorption efficiency.

[0033] 3. The present invention selects nano-magnesium chromite spinel and carbon nanotube-modified nickel manganese lithium spinel as the spinel material combination. The nano-scale particles of nano-magnesium chromite spinel can form a porous or rough surface, increasing the number of reflections and the path of light in the coating; the carbon nanotube-modified nickel manganese lithium spinel has surface porosity, and by utilizing the different reflection effects of the microporous rough surface on spectra of different wavelengths, the morphology and structure of the coating surface are controlled, increasing the average absorption rate of the effective band and the solar energy absorption efficiency.

[0034] 4. The present invention selects sodium silicate and tetraethyl orthosilicate as the compound binder. Through the synergistic effect of sodium silicate and tetraethyl orthosilicate, sodium silicate provides macroscopic adhesion and a high-temperature resistant skeleton, and tetraethyl orthosilicate fills the micro-pores and optimizes the surface roughness, forming a multi-level structure to reduce light reflection, increasing the average absorption rate of the effective band and the solar energy absorption efficiency. Specific Embodiments

[0035] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art without making creative efforts based on the embodiments of the present invention belong to the scope of protection of the present invention.

[0036] The sources of some components in the examples and comparative examples are as follows: Copper nitrate, CAS No. 10031-43-3, purchased from Sinopharm Chemical Reagent Co., Ltd.; Cobalt chloride, CAS No. 7791-13-1, purchased from Sinopharm Chemical Reagent Co., Ltd.; Sodium citrate, CAS No. 68-04-2, was purchased from Sinopharm Chemical Reagent Co., Ltd.; Graphene oxide, product number G139803, was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; Commercially available copper oxide, product number C299304, was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; Nano magnesium chromium spinel, product number Q-0008424, was purchased from Xi’an Qiyue Biotechnology Co., Ltd.; Carbon nanotube-modified lithium nickel manganese oxide spinel, catalog number Q-0066176, was purchased from Xi’an Qiyue Biotechnology Co., Ltd.; Sodium silicate, CAS No. 13517-24-3, was purchased from Sinopharm Chemical Reagent Co., Ltd.; Tetraethyl orthosilicate, CAS No. 78-10-4, was purchased from Sinopharm Chemical Reagent Co., Ltd.; Dispersant: Mayer Chemical HY-2600, Mayer Chemical HY-168, Digo Dispers-760W; Defoaming agent: Maier Chemical HY-1042, Digo Tego825, Digo Airex-902W; Leveling agent: AFCONA-3587, Maier Chemical HY-5030.

[0037] Example 1 This embodiment provides a method for preparing a CuO-based heat-absorbing coating. The following steps are involved: S1: sandblasting the substrate surface to obtain a pretreated substrate; S2: In parts by weight, 1.2 parts of dispersant Maier Chemical HY-2600, 1.2 parts of defoamer Maier Chemical HY-1042 and 1.2 parts of leveling agent AFCONA-3587 are added to 60 parts of binder (40 parts of sodium silicate and 20 parts of tetraethyl orthosilicate) and stirred thoroughly, and then 30 parts of modified copper oxide and 15 parts of spinel material (10 parts of nano magnesium chromium spinel and 5 parts of carbon nanotube modified lithium nickel manganese oxide spinel) are added and dispersed uniformly at high speed to obtain a mixture, and the mixture is transferred to a ball mill for ball milling (rotating speed of 400 rpm, time of 3 hours) to obtain a coating; S3: Spray the coating onto the surface of the pretreated substrate, let it stand overnight, and then perform a curing treatment (first curing at room temperature for 24 hours, then heating to 500° C. for curing for 6 hours) to obtain a CuO-based heat-absorbing coating.

[0038] Preparation of the modified copper oxide: By weight, 20 parts of copper nitrate and 4 parts of cobalt chloride are added to 260 parts of deionized water and dissolved thoroughly. After heating to 80 °C, 50 parts of 2 mol / L sodium hydroxide aqueous solution and 4 parts of 0.2 g / ml sodium citrate aqueous solution are added successively for heat treatment (control the temperature at 100 °C for constant temperature reaction for 10 min). Then, 4 parts of graphene oxide are added and ultrasonically dispersed for 10 min. It is transferred to a reaction kettle, and hydrothermal reaction is carried out at 180 °C for 2 h. After cooling to room temperature, it is washed with water and dried; then it is transferred to a muffle furnace and calcined at a rate of 6 °C / min to 360 °C for 100 min, and cooled with the furnace to obtain the modified copper oxide.

[0039] Example 2 This example provides a preparation method of a CuO-based endothermic coating. It includes the following steps: S1: The surface of the substrate is sandblasted to obtain a pretreated substrate. S2: By weight, 0.8 part of dispersant Mel Chemical HY-168, 0.8 part of defoamer Degussa Tego825 and 0.8 part of leveling agent Mel Chemical HY-5030 are added to 50 parts of binder (25 parts of sodium silicate and 25 parts of tetraethyl orthosilicate) and stirred thoroughly. Then, 20 parts of modified copper oxide and 10 parts of spinel materials (5 parts of nano magnesium chromite spinel and 5 parts of carbon nanotube-modified lithium nickel manganate spinel) are added and dispersed uniformly at high speed to obtain a mixture. The mixture is transferred to a ball mill for ball milling treatment (rotation speed is 300 rpm, time is 5 h) to obtain a coating. S3: The coating is sprayed on the surface of the pretreated substrate, left standing overnight and then cured (first cured at room temperature for 20 h, and then heated to 480 °C for curing for 8 h) to obtain a CuO-based endothermic coating.

[0040] Preparation of the modified copper oxide: By weight, 16 parts of copper nitrate and 2 parts of cobalt chloride are added to 240 parts of deionized water and dissolved thoroughly. After heating to 70 °C, 40 parts of 1 mol / L sodium hydroxide aqueous solution and 2 parts of 0.1 g / ml sodium citrate aqueous solution are added successively for heat treatment (control the temperature at 96 °C for constant temperature reaction for 20 min). Then, 2 parts of graphene oxide are added and ultrasonically dispersed for 6 min. It is transferred to a reaction kettle, and hydrothermal reaction is carried out at 170 °C for 4 h. After cooling to room temperature, it is washed with water and dried; then it is transferred to a muffle furnace and calcined at a rate of 4 °C / min to 340 °C for 120 min, and cooled with the furnace to obtain the modified copper oxide.

[0041] Example 3 This example provides a preparation method of a CuO-based endothermic coating. It includes the following steps: S1: Sandblast the surface of the substrate to obtain a pretreated substrate; S2: By weight, add 0.9 parts of dispersant Disperbyk - 760W, 1.1 parts of defoamer Tego Airex - 902W, and 0.9 parts of leveling agent Efka - 3587 to 55 parts of binder (35 parts of sodium silicate and 20 parts of tetraethyl orthosilicate), stir well, then add 25 parts of modified copper oxide and 12 parts of spinel material (7 parts of nano - magnesium chromite spinel and 5 parts of carbon nanotube - modified lithium nickel manganese oxide spinel), disperse uniformly at high speed to obtain a mixture, transfer the mixture to a ball mill for ball - milling treatment (rotation speed is 350 rpm, time is 4 h) to obtain a coating; S3: Spray the coating on the surface of the pretreated substrate, let it stand overnight and then carry out curing treatment (first cure at room temperature for 22 h, then raise the temperature to 490 °C and cure for 7 h) to obtain a CuO - based endothermic coating.

[0042] Preparation of the modified copper oxide: By weight, add 18 parts of copper nitrate and 3 parts of cobalt chloride to 250 parts of deionized water and dissolve fully. After heating to 75 °C, add 45 parts of 1.5 mol / L sodium hydroxide aqueous solution and 3 parts of 0.15 g / ml sodium citrate aqueous solution in sequence for heat treatment (control the temperature at 98 °C for constant - temperature reaction for 15 min), then add 3 parts of graphene oxide and ultrasonically disperse for 8 min, transfer to a reaction kettle, control the temperature at 175 °C for hydrothermal reaction for 3 h, cool to room temperature, wash with water and dry; transfer to a muffle furnace, heat up to 350 °C at a rate of 5 °C / min for calcination for 110 min, and cool with the furnace to obtain modified copper oxide.

[0043] Comparative Example 1 The difference between this comparative example and Example 1 is that commercially available copper oxide (product number C299304) is used to replace the modified copper oxide.

[0044] Comparative Example 2 The difference between this comparative example and Example 1 is that the dosage of nano - magnesium chromite spinel is changed to 13 parts and the dosage of carbon nanotube - modified lithium nickel manganese oxide spinel is changed to 2 parts.

[0045] Comparative Example 3 The difference between this comparative example and Example 1 is that the dosage of nano - magnesium chromite spinel is changed to 5 parts and the dosage of carbon nanotube - modified lithium nickel manganese oxide spinel is changed to 10 parts.

[0046] Comparative Example 4 The difference between this comparative example and Example 1 is that the dosage of sodium silicate is changed to 50 parts and the dosage of tetraethyl orthosilicate is changed to 10 parts.

[0047] Comparative Example 5 The difference between this comparative example and Example 1 is that the dosage of sodium silicate is changed to 20 parts, and the dosage of tetraethyl orthosilicate is changed to 40 parts.

[0048] Performance Test The coatings prepared in the above examples and comparative examples were subjected to the following tests: Average absorption rate in the effective band: For the absorption rate test in the integral sphere ultraviolet and visible light bands, refer to "GB / T 41307-2022 Test Method for Absorbers in Tower-Type Solar Thermal Power Plants".

[0049] Solar absorption efficiency: The test was carried out according to the requirements of "GB / T 25968-2010 Test Method for Measuring Solar Transmittance and Solar Absorptance of Materials by Spectrophotometer".

[0050] Table 1 Performance Test Results

[0051] From the above performance test results, it can be seen that the comprehensive performance of Examples 1-3 is the best, with the average absorption rate in the effective band being 95.2~95.7%, and the solar absorption efficiency being 91.6~92.1%. This is mainly because the modified copper oxide is obtained through the synergistic preparation of cobalt doping and graphene oxide, and with the use of spinel materials and compound binders, a heat-absorbing coating is prepared. With the combined action of multiple components, the average absorption rate in the effective band and the solar absorption efficiency of the coating are effectively improved.

[0052] Compared with Example 1, in Comparative Example 1, commercially available copper oxide (product number C299304) was used to replace the modified copper oxide, resulting in a decrease in the average absorption rate in the effective band and the solar absorption efficiency; compared with Example 1, in Comparative Example 2, the dosage of nano-magnesium chromite spinel was changed to 13 parts, and the dosage of carbon nanotube-modified lithium nickel manganate spinel was changed to 2 parts. Due to the too small dosage of carbon nanotube-modified lithium nickel manganate spinel, the compounding effect was poor, resulting in a decrease in the average absorption rate in the effective band and the solar absorption efficiency; compared with Example 1, in Comparative Example 3, the dosage of nano-magnesium chromite spinel was changed to 5 parts, and the dosage of carbon nanotube-modified lithium nickel manganate spinel was changed to 10 parts. Due to the too small dosage of nano-magnesium chromite spinel, the compounding effect was poor, resulting in a decrease in the average absorption rate in the effective band and the solar absorption efficiency; compared with Example 1, in Comparative Example 4, the dosage of sodium silicate was changed to 50 parts, and the dosage of tetraethyl orthosilicate was changed to 10 parts. Due to the too small dosage of tetraethyl orthosilicate, the formed void structure was small, and the compounding effect was poor, resulting in a decrease in the average absorption rate in the effective band and the solar absorption efficiency; compared with Example 1, in Comparative Example 5, the dosage of sodium silicate was changed to 20 parts, and the dosage of tetraethyl orthosilicate was changed to 40 parts. Due to the too small dosage of sodium silicate, the binding effect of the binder was reduced, and the compounding effect was poor, resulting in a decrease in the average absorption rate in the effective band and the solar absorption efficiency.

Claims

1. A CuO-based endothermic coating, characterized in that by weight, the coating comprises the following components: 20-30 parts of modified copper oxide, 10-15 parts of spinel material, 50-60 parts of binder, 0.8-1.2 parts of dispersant, 0.8-1.2 parts of defoamer and 0.8-1.2 parts of leveling agent; The preparation method of the modified copper oxide comprises: by weight, adding 16-20 parts of copper nitrate and 2-4 parts of cobalt chloride into 240-260 parts of deionized water to dissolve completely, heating to 70-80 °C and then successively adding 40-50 parts of 1-2 mol / L sodium hydroxide aqueous solution and 2-4 parts of 0.1-0.2 g / ml sodium citrate aqueous solution for heat treatment, then adding 2-4 parts of graphene oxide for hydrothermal reaction, and obtaining modified copper oxide after calcination treatment.

2. A CuO-based endothermic coating according to claim 1, characterized in that the steps of the hydrothermal reaction include: first ultrasonically dispersing for 6-10 min, transferring to a reaction kettle, controlling the temperature at 170-180 °C for hydrothermal reaction for 2-4 h, cooling to room temperature, washing with water, and drying.

3. A CuO-based endothermic coating according to claim 1, characterized in that the steps of the calcination treatment include: transferring to a muffle furnace, heating at a rate of 4-6 °C / min to 340-360 °C for calcination for 100-120 min, and cooling with the furnace.

4. A CuO-based endothermic coating according to claim 1, characterized in that the spinel material is nano-magnesium chromium spinel and carbon nanotube modified lithium nickel manganate spinel; the mass ratio of nano-magnesium chromium spinel to carbon nanotube modified lithium nickel manganate spinel in the spinel material is (1-2):

1.

5. A CuO-based endothermic coating according to claim 1, characterized in that the binder is sodium silicate and tetraethyl orthosilicate; the mass ratio of sodium silicate to tetraethyl orthosilicate in the binder is (1-2):

1.

6. A CuO-based endothermic coating according to claim 1, characterized in that the dispersant is selected from one or more of Mel Chemical HY-2600, Mel Chemical HY-168, and Degussa Dispers-760W.

7. A CuO-based endothermic coating according to claim 1, characterized in that the defoamer is selected from one or more of Mel Chemical HY-1042, Degussa Tego825, and Degussa Airex-902W.

8. A CuO-based endothermic coating according to claim 1, characterized in that the leveling agent is selected from Efka AFCONA-3587 or Mel Chemical HY-5030.

9. A preparation method of a CuO-based endothermic coating according to any one of claims 1-8, characterized in that it comprises the following steps: S1: Sandblasting the surface of the substrate to obtain a pretreated substrate; S2: By weight, 0.8 - 1.2 parts of a dispersant, 0.8 - 1.2 parts of an antifoaming agent, and 0.8 - 1.2 parts of a leveling agent are added to 50 - 60 parts of a binder and stirred well. Then, 20 - 30 parts of modified copper oxide and 10 - 15 parts of a spinel material are added and dispersed uniformly at high speed to obtain a mixture. The mixture is transferred to a ball mill for ball milling treatment to obtain a coating; S3: The coating is sprayed on the surface of a pretreated substrate, allowed to stand overnight, and then subjected to a curing treatment to obtain a CuO-based endothermic coating.

10. Use of a CuO-based endothermic coating according to any one of claims 1 - 8 in an endothermic device.

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