Functional protective coating and preparation method thereof

Abstract

The present application relates to a kind of functional protective coating, the coating is made of the following mass parts of raw materials: functional pigment 10~13 parts, filler 2~5 parts, high temperature resistant resin 21~43 parts, anhydrous ethanol 43.7~51 parts, dispersing agent 4~10 parts, defoaming agent 0.3~1.1 parts, leveling agent 3~6 parts;The functional pigment is high-entropy boride ceramic material, the cation in the high-entropy boride ceramic material is at least 5 kinds in metal element Co, Ni, Cr, Cu, Fe and Mo, and each metal element is equimolar ratio.Simultaneously, the preparation method of the functional protective coating is disclosed.The coating obtained by the present application has the characteristics of excellent performance, wide application range, low cost and simple construction process, and has high temperature corrosion resistance, anti-coking, high infrared radiation and solar absorption capacity.

Description

Technical Field

[0001] This invention relates to the technical field of composite materials that combine energy saving and protection, and in particular to a functional protective coating and its preparation method. Background Technology

[0002] In 2021, with rising coal prices, especially the persistently high prices of high-calorific-value coal, it became impossible for these coals to be used as the primary type of coal in boilers. Blending with lower-priced, lower-calorific-value coals became a necessary means for coal-fired power plants to reduce fuel costs. However, this resulted in incomplete combustion of the coal, leading to excessively low calorific value and leaving a large amount of coal ash inside the boiler furnace, resulting in coal waste. If this coal ash is not cleaned promptly, its long-term accumulation inside the boiler furnace will gradually cause coking, slagging, and high-temperature corrosion, ultimately reducing the boiler's safety and economic efficiency. CN 115160835A discloses a micro-nano multi-scale anti-coking and wear-resistant coating, composite material, and preparation method thereof. Through the synergistic combination of various components in the coating and particle size control, a micro-nano multi-scale coating with poor wettability in high-temperature liquid or molten ash, low friction coefficient, anti-coking, wear-resistant, crack-resistant, and excellent heat transfer and corrosion-resistant properties is prepared, providing an effective solution to the problem of anti-coking on the heating surface of coal-fired boilers.

[0003] All objects with temperatures above absolute zero release energy through electromagnetic waves. The infrared thermal radiation loss of common objects is mainly concentrated in the 2.5–20 μm wavelength range. These electromagnetic waves can be absorbed by objects, causing resonance in the internal particles and thus raising the object's temperature. As the temperature inside the furnace rises, radiative heat transfer will replace convective heat transfer as the dominant process. Therefore, the protective coating inside the furnace should possess both protective and high infrared emission properties, serving both furnace protection and energy-saving efficiency enhancement.

[0004] Patent CN 114316718 A discloses a weather-resistant infrared radiation heat dissipation industrial coating and its preparation method, comprising organosilicon-modified acrylic resin, infrared radiation powder, modified graphene nanosheets, defoamer, dispersant, anti-settling agent, wetting agent, film-forming agent, and leveling agent. This coating exhibits excellent infrared radiation heat dissipation function and good weather resistance. However, the modified graphene nanosheets require glow discharge to be produced, a complex process with high equipment requirements, high energy consumption, and high production costs, making it unsuitable for large-scale industrial applications. Patent CN 113214685 A proposes a high-temperature, high-emissivity infrared radiation coating and its preparation and application methods. This coating is obtained by mixing copper oxide-doped magnesium chromium spinel fine powder, silicified expanded graphite, Guangxi white clay, elemental silicon powder, glass powder, silica sol, glycerol, and citric acid using a planetary ball mill. The high-temperature, high-emissivity infrared radiation coating is uniformly applied to the surface of an industrial kiln wall, air-dried, and then heat-treated at 110–700°C for 1–4 hours to obtain a high-temperature, high-infrared radiation coating. The coating exhibits excellent infrared radiation performance and high-temperature stability. However, its raw material, copper oxide-doped magnesium chromium spinel powder, needs to be prepared at high temperatures (1150–1350°C), requiring sophisticated production equipment. Although the samples in the above patents yielded excellent infrared radiation coatings with excellent high-temperature thermal stability, they did not consider the complex working conditions inside the furnace, such as coking and wear, thus limiting their application.

[0005] The surface temperature of the sun is 5780 K, and the electromagnetic waves it emits are mainly distributed in the 0.3~2.5 μm wavelength range. Photothermal conversion is the most direct way to utilize solar energy and is a key component of solar thermal power plants. Absorption rate is the main standard for measuring its performance, and its performance and lifespan directly determine the benefits of the power plant. Therefore, the absorption properties of materials can be controlled to achieve excellent absorption performance in a wide spectral range (0.3~20 μm), simultaneously meeting the application requirements of both solar thermal conversion and infrared radiation scenarios, such as solar tower solar thermal power plants and boiler internal protection and enhanced heat transfer. Therefore, this can promote the conversion and utilization of renewable energy and improve the efficiency of primary energy use, representing an effective measure to achieve dual-carbon goals and possessing significant academic and applied value. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a functional protective coating with excellent performance, wide application range, low cost, simple construction process, and high resistance to high temperature corrosion, anti-coking, and high infrared radiation and solar energy absorption capacity.

[0007] Another technical problem to be solved by the present invention is to provide a method for preparing the functional protective coating.

[0008] To solve the above problems, the present invention provides a functional protective coating, characterized in that: the coating is made from the following raw materials in parts by weight: 10-13 parts functional pigment, 2-5 parts filler, 21-43 parts high-temperature resistant resin, 43.7-51 parts anhydrous ethanol, 4-10 parts dispersant, 0.3-1.1 parts defoamer, and 3-6 parts leveling agent; the functional pigment is a high-entropy boride ceramic material, wherein the cations in the high-entropy boride ceramic material are at least five of the metal elements Co, Ni, Cr, Cu, Fe, and Mo, and each metal element is in an equimolar ratio.

[0009] The high-entropy boride ceramic material is prepared by the following method: using five nitrates or sulfates from powders of Co(NO3)3·6H2O, Ni(NO3)2·6H2O, Cr(NO3)3·9H2O, Cu(NO3)2·3H2O, Mo(NO3)3·5H2O, and FeSO4·7H2O as raw materials, sodium borohydride as the boron source, and the molar ratio of total metal elements to sodium borohydride is 1:4; the raw materials and the boron source are dissolved in deionized water pre-purged with nitrogen or argon for 30-60 minutes using a mechanical stirrer at a speed of 300-500 r / min; the resulting salt solution is mixed with the boron source aqueous solution and subjected to a reduction reaction, followed by vacuum filtration; during filtration, the filter cake is washed 3-6 times alternately with deionized water and anhydrous ethanol, each time for 1 minute; finally, it is first frozen at -24 °C for 12 h, and then frozen at a freezing temperature of -50 to -62 °C. Freeze-dry at °C, vacuum degree of 38~43 Pa, and duration of 8~12 h until all ice crystals are observed to disappear.

[0010] The high-entropy boride ceramic material has a particle size of 100~300 nm and a specific surface area of ​​10~100 m². 2 / g.

[0011] The filler is nano-cerium oxide with a fluorite phase, a particle size of 20-30 nm, and a specific surface area of ​​10-20 m². 2 / g.

[0012] The high-temperature resistant resin is at least one of perhydropolysilazane and polyureasilazane.

[0013] The dispersant is Evcona AFCONA-4011.

[0014] The defoamer is Evcona AFCONA-2027.

[0015] The leveling agent is Evcona AFCONA-3034.

[0016] The preparation method of the functional protective coating as described above is characterized by the following: First, the ingredients are weighed according to the specified ratio. Then, anhydrous ethanol, dispersant, defoamer, leveling agent and high-temperature resistant resin are stirred, dispersed and mixed, and functional pigments and fillers are added. The mixture is stirred for 50 to 90 minutes at a speed of 800 to 1200 r / min using a high-speed disperser. Then, it is dispersed and ground to a fineness of 20 to 35 μm using a sand mill or ball mill. Finally, it is filtered through a 400 to 750 mesh screen to obtain the functional protective coating.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] 1. This invention uses at least one of perhydropolysilazane and polyureasilazane as a high-temperature resistant resin. The presence of silicon-nitrogen bonds and carbon-nitrogen bonds in this resin makes its molecular structure very stable, allowing it to maintain its structure unchanged under high-temperature environments. Simultaneously, the silicon and nitrogen elements present in this resin enhance its corrosion resistance; while the presence of carbon gives it high hardness and wear resistance. This results in the coating of this invention exhibiting excellent high-temperature and corrosion resistance, making it suitable for use in high-temperature, corrosive, and high-wear environments such as industrial furnaces. The polysilazane coating has a high crosslinking density and low surface energy, resulting in a low surface energy characteristic in the coating. When the surface energy of the heated surface is lower than the critical free energy of the molten coke particles, the coke particles cannot adhere to the heated surface, effectively preventing water-cooled wall fouling and reducing coking. Even if a small amount of coking occurs, due to the very low surface energy of the coating, the coke particles exceed the critical value of adhesion at a small size and detach on their own, thus preventing the formation of large coke deposits and achieving an anti-coking effect.

[0019] 2. This invention uses high-entropy boride materials as functional pigments. The high-entropy effect brought about by the multi-principal element design contributes to its structural stability. Secondly, the multi-principal element design can reduce the band gap by increasing the band intensity near the Fermi level, and increase lattice vibrations due to the lattice distortion effect caused by differences in atomic size, mass, and valence state, thereby achieving high solar energy absorption and broadband infrared radiation.

[0020] 3. This invention uses nano-cerium oxide material as a filler, whose 4f electronic structure enhances light absorption and infrared radiation capabilities. It also improves the coating's corrosion resistance, mechanical properties, and thermal stability.

[0021] 4. The method of this invention is simple, requires no complex equipment, has high production efficiency, does not require complex heat treatment processes, and can achieve large-scale industrial production. It exhibits excellent absorption capacity in the infrared spectrum (2.5~20 μm) and possesses excellent high-temperature stability, corrosion resistance, wear resistance, and anti-coking properties, making it suitable for protection and enhancing radiative heat transfer efficiency within furnaces. Simultaneously, this coating exhibits high absorption performance in the solar spectrum (0.3~2.5 μm), achieving effective utilization of a wide-band solar spectrum, and can be applied in the field of solar thermal power generation.

[0022] 5. Performance testing of the coating obtained by this invention:

[0023] Test procedure: The solvent-based functional coating prepared in this invention was applied to the substrate (nickel-based alloy 625) by spraying, and then placed in a muffle furnace at 150~200 °C for 2 hours and allowed to cool naturally. The dry film thickness was 25~60 μm.

[0024] Solar energy absorption rate, infrared emissivity

[0025] The absorptivity and emissivity of the coating were tested using a Lambda 950 UV-Vis-NIR spectrophotometer (with a 150 mm integrating sphere) from the United States and a Bruker Tensor 27 infrared spectrometer (with an integrating sphere) from Germany, in accordance with the national standard GB / T 26974-2011.

[0026] Test results: The coating has a solar energy absorption rate greater than 0.94 in the 0.3~2.5 μm band, indicating good light absorption performance, and an infrared emissivity greater than 0.93 in the 2.5~20 μm band, indicating excellent infrared emission characteristics.

[0027] High temperature resistance

[0028] The coating was placed in an air atmosphere in a box furnace and subjected to a thermal stability test at 1000 °C for 720 h. The results showed that the coating prepared by the present invention has a stable structure, and the fluctuation of solar absorptivity is only 0.02~0.06, and the fluctuation of infrared emissivity is only 0.01~0.05.

[0029] Thermal shock resistance

[0030] The coating was placed in an air atmosphere in a box furnace and heated to 1000 °C at a heating rate of 5 °C / min. After holding at that temperature for 1 hour, the coating was removed and cooled by water quenching. This process was repeated 20 times, and the coating surface was observed.

[0031] Test results: The coating surface is intact, with no peeling or cracks.

[0032] Adhesion

[0033] The adhesion of the coating was tested using the pull-out method, with reference to ASTM D 4541, "Determination of the pull-out strength of coatings using a portable adhesion tester".

[0034] Test results: The coating pull-out strength is greater than 5 MPa.

[0035] [Coating Salt Spray Corrosion Resistance Test]

[0036] Artificial Atmosphere Corrosion Test - Salt Spray Test (NSS), Test Standard: GB / T 10125-2012.

[0037] Test results: After 720 hours of salt spray testing, the coating remained intact and no corrosion occurred. Detailed Implementation

[0038] A functional protective coating is made from the following raw materials in parts by weight (g): 10-13 parts functional pigment, 2-5 parts filler, 21-43 parts high-temperature resistant resin, 43.7-51 parts anhydrous ethanol, 4-10 parts dispersant, 0.3-1.1 parts defoamer, and 3-6 parts leveling agent; wherein the functional pigment is a high-entropy boride ceramic material, and the cations in the high-entropy boride ceramic material are at least five of the following metal elements: Co, Ni, Cr, Cu, Fe, and Mo, and each metal element is in an equimolar ratio.

[0039] The filler is nano-cerium oxide with a fluorite phase, a particle size of 20-30 nm, and a specific surface area of ​​10-20 m². 2 / g.

[0040] The high-temperature resistant resin is at least one of perhydropolysilazane and polyureasilazane.

[0041] The dispersant is Evcona AFCONA-4011.

[0042] The defoamer used is Evcona AFCONA-2027.

[0043] The leveling agent is Evcona AFCONA-3034.

[0044] High-entropy boride ceramic materials are prepared by the following method: Five nitrates or sulfates from powders of Co(NO3)3·6H2O, Ni(NO3)2·6H2O, Cr(NO3)3·9H2O, Cu(NO3)2·3H2O, Mo(NO3)3·5H2O, and FeSO4·7H2O are used as raw materials, with sodium borohydride as the boron source, and the molar ratio of total metal elements to sodium borohydride is 1:4. The raw materials and boron source are dissolved separately in deionized water pre-purged with nitrogen or argon for 30–60 minutes using a mechanical stirrer at a speed of 300–500 r / min. The resulting salt solution is mixed with the boron source aqueous solution and subjected to a reduction reaction, followed by vacuum filtration. During filtration, the filter cake is washed 3–6 times alternately with deionized water and anhydrous ethanol, each time for 1 minute. Finally, the mixture is first frozen at -24 °C for 12 h, and then further frozen at a temperature of -50 to -62 °C. Freeze-dry at °C, vacuum degree of 38–43 Pa, and duration of 8–12 h until all ice crystals are observed to disappear. The resulting high-entropy boride ceramic material has a particle size of 100–300 nm and a specific surface area of ​​10–100 m². 2 / g.

[0045] The dissolution time of nitrates or sulfates is 30 to 60 minutes; the mass ratio of raw material to water (g / g) is (1.502 to 1.667):150, and the metal atoms in the raw material are in equimolar ratio.

[0046] The reduction reaction is carried out as follows: the sodium borohydride aqueous solution is slowly injected into the salt solution using a syringe, and the reaction is allowed to proceed for 30 to 40 minutes; the mass ratio (g / g) of sodium borohydride to deionized water in the sodium borohydride aqueous solution is 0.757:50.

[0047] In this preparation method, the reaction solution is continuously purged with nitrogen or argon gas, and the reaction vessel is cooled at 0~5°C during the preparation process.

[0048] A method for preparing a functional protective coating: First, weigh the ingredients according to the specified ratio. Then, stir and disperse anhydrous ethanol, dispersant, defoamer, leveling agent, and high-temperature resistant resin. Add functional pigments and fillers, and stir the mixture for 50-90 minutes at a speed of 800-1200 r / min using a high-speed disperser. Then, disperse and grind the mixture to a fineness of 20-35 μm using a sand mill or ball mill. Finally, filter the mixture through a 400-750 mesh screen to obtain the functional protective coating.

[0049] Example 1

[0050] (1) Preparation of functional pigment (CoNiCuFeMo)B2

[0051] Weigh out 0.291 g (1 mmol) of Co(NO3)3·6H2O, 0.291 g (1 mmol) of Ni(NO3)2·6H2O, 0.242 g (1 mmol) of Cu(NO3)2·3H2O, 0.278 g (1 mmol) of FeSO4·7H2O, and 0.443 g (1 mmol) of Mo(NO3)3·5H2O powder respectively. Dissolve the weighed raw materials in 150 g of deionized water that has been purged with nitrogen for 30 min. Stir the mixture with a mechanical stirrer at 400 r / min for 30 min to obtain a salt solution.

[0052] Dissolve 0.757 g (20 mmol) of NaBH4 in 50 g of deionized water that has been purged with nitrogen for 60 min to obtain an aqueous solution of sodium borohydride.

[0053] Sodium borohydride aqueous solution was slowly added to the salt solution using a syringe, and the reaction was allowed to proceed for 30 min. The resulting solution was then filtered under vacuum, with the sample being washed six times alternately with deionized water and ethanol. The filtered sample was first frozen at -24 °C for 12 h, and then placed in a freeze dryer at -50 °C and a vacuum of 43 Pa for 12 h, until all ice crystals were observed to have disappeared, thus obtaining (CoNiCuFeMo)B2 high-entropy boride powder.

[0054] (2) Preparation of functional coatings

[0055] Based on a total weight of 1 kg, the coating formulation (by mass parts) is as follows: (CoNiCuFeMo)B2: 10%, cerium oxide: 2%, perhydropolysilazane: 43%, anhydrous ethanol: 47.7%, AFCONA-4011: 4%, AFCONA-2027: 0.3%, AFCONA-3034: 3%.

[0056] Preparation process:

[0057] Anhydrous ethanol, dispersant AFCONA-4011, defoamer AFCONA-2027, leveling agent AFCONA-3034, and perhydropolysilazane were sequentially added to a container and stirred to disperse. Then, functional pigment (CoNiCuFeMo) B2 and filler cerium oxide (particle size 30 nm, specific surface area 10 m²) were added. 2 / g). Stir at 800 r / min for 50 min using a high-speed disperser, then disperse and grind to a fineness of 20 μm using a sand mill or ball mill. Filter the mixture through a 750 mesh screen, and then pack the filtered coating into a container and seal it.

[0058] (3) Preparation of coating

[0059] The coating (nickel-based alloy 625) was applied to the substrate using a spraying method, and then the substrate was placed in a muffle furnace at 200 °C for 2 hours and allowed to cool naturally. The dry film thickness of the coating was 25 μm. The performance indicators of the coating are shown in Table 1.

[0060] Example 2

[0061] (1) Preparation of functional pigment (CoCrNiCuMo)B2

[0062] Weigh out 0.291 g (1 mmol) of Co(NO3)3·6H2O, 0.4 g (1 mmol) of Cr(NO3)3·9H2O, 0.291 g (1 mmol) of Ni(NO3)2·6H2O, 0.242 g (1 mmol) of Cu(NO3)2·3H2O, and 0.443 g (1 mmol) of Mo(NO3)3·5H2O powder respectively. Dissolve the weighed raw materials in 150 g of deionized water that has been purged with nitrogen for 40 min. Stir the mixture with a mechanical stirrer at 400 r / min for 30 min to obtain a salt solution.

[0063] Dissolve 0.757 g (20 mmol) of NaBH4 in 50 g of deionized water that has been purged with nitrogen for 60 min to obtain an aqueous solution of sodium borohydride.

[0064] Sodium borohydride aqueous solution was slowly added to the salt solution using a syringe, and the reaction was allowed to proceed for 30 min. The resulting solution was then filtered under vacuum, with the sample washed three times alternately with deionized water and ethanol. The filtered sample was first frozen at -24 °C for 12 h, then placed in a freeze dryer at -62 °C and a vacuum of 40 Pa for 10 h, until all ice crystals were observed to have disappeared, thus obtaining (CoCrNiCuMo)B2 high-entropy boride powder.

[0065] (2) Preparation of functional coatings

[0066] Based on a total weight of 1 kg, the coating formulation (by mass parts) is as follows: (CoCrNiCuMo)B2: 8%, cerium oxide: 2.5%, perhydropolysilazane: 30%, anhydrous ethanol: 51%, AFCONA-4011: 4.5%, AFCONA-2027: 0.4%, AFCONA-3034: 3.6%.

[0067] Preparation process:

[0068] Anhydrous ethanol, dispersant AFCONA-4011, defoamer AFCONA-2027, leveling agent AFCONA-3034, and perhydropolysilazane were sequentially added to a container and stirred to disperse. Then, functional pigment (CoCrNiCuMo) B2 and filler cerium oxide (particle size 20 nm, specific surface area 20 m²) were added. 2 / g). Stir at 1000 r / min for 70 min using a high-speed disperser, then disperse and grind to a fineness of 30 μm using a sand mill or ball mill. Filter the mixture through a 500-mesh screen, and then seal the filtered coating in a container.

[0069] (3) Preparation of coating

[0070] The coating (nickel-based alloy 625) was applied to the substrate using a spraying method, and then the substrate was placed in a muffle furnace at 200 °C for 2 hours and allowed to cool naturally. The dry film thickness of the coating was 25 μm. The performance indicators of the coating are shown in Table 1.

[0071] Example 3

[0072] (1) Preparation of functional pigment (CoCrNiCuFe)B2

[0073] Weigh out 0.291 g (1 mmol) of Co(NO3)3·6H2O, 0.4 g (1 mmol) of Cr(NO3)3·9H2O, 0.291 g (1 mmol) of Ni(NO3)2·6H2O, 0.242 g (1 mmol) of Cu(NO3)2·3H2O, and 0.278 g (1 mmol) of FeSO4·7H2O powder respectively. Dissolve the weighed raw materials in 150 g of deionized water that has been purged with nitrogen for 30 min. Stir the mixture with a mechanical stirrer at 350 r / min for 35 min to obtain a salt solution.

[0074] Dissolve 0.757 g (20 mmol) of NaBH4 in 50 g of deionized water that has been purged with nitrogen for 70 min to obtain an aqueous solution of sodium borohydride.

[0075] Sodium borohydride aqueous solution was slowly added to the salt solution using a syringe, and the reaction was allowed to proceed for 30 minutes. The resulting solution was then filtered under vacuum, with the sample being washed four times alternately with deionized water and ethanol. The filtered sample was first frozen at -24 °C for 12 hours, and then placed in a freeze dryer at -60 °C and a vacuum of 38 Pa for 8 hours, until all ice crystals were observed to have disappeared, thus obtaining (CoCrNiCuFe)B2 high-entropy boride powder.

[0076] (2) Preparation of functional coatings

[0077] Based on a total weight of 1 kg, the coating formulation (by mass parts) is as follows: (CoCrNiCuFe)B2: 13%, cerium oxide: 5%, polyurea silazane: 21%, anhydrous ethanol: 43.9%, AFCONA-4011: 10%, AFCONA-2027: 1.1%, AFCONA-3034: 6%.

[0078] Preparation process:

[0079] Anhydrous ethanol, dispersant AFCONA-4011, defoamer AFCONA-2027, leveling agent AFCONA-3034, and polyurea silazane were sequentially added to a container and stirred to disperse. Then, functional pigment (CoCrNiCuFe) B2 and filler cerium oxide (particle size 25 nm, specific surface area 15 m²) were added. 2 / g). Stir at 1200 r / min for 90 min using a high-speed disperser, then disperse and grind to a fineness of 35 μm using a sand mill or ball mill. Filter the mixture through a 400-mesh screen, and then seal the filtered coating in a container.

[0080] (3) Preparation of coating

[0081] The coating (nickel-based alloy 625) was applied to the substrate using a spraying method, and then the substrate was placed in a muffle furnace at 150 °C for 2 hours and allowed to cool naturally. The dry film thickness of the coating was 65 μm. The performance indicators of the coating are shown in Table 1.

[0082] Table 1. Performance characterization of coatings prepared in Examples 1-3

[0083]

[0084] As shown in Table 1, the functional protective coating prepared by the present invention using high-entropy boride ceramics as functional pigments has high absorption performance in a wide spectral range (0.3~20 μm), exhibiting high solar energy absorption rate and good infrared emission characteristics. It also has excellent adhesion, high temperature resistance, thermal shock resistance and corrosion resistance, which can meet the needs of use under various working conditions.

Claims

1. A functional protective coating, characterized in that: The coating is made from the following raw materials in parts by weight: 10-13 parts functional pigment, 2-5 parts filler, 21-43 parts high-temperature resistant resin, 43.7-51 parts anhydrous ethanol, 4-10 parts dispersant, 0.3-1.1 parts defoamer, and 3-6 parts leveling agent; the functional pigment is a high-entropy boride ceramic material, wherein the cations in the high-entropy boride ceramic material are at least five of the following metal elements: Co, Ni, Cr, Cu, Fe, and Mo, and each metal element is in an equimolar ratio; the high-entropy boride ceramic material is prepared according to the following... The method yields the following: Five nitrates or sulfates from powders of Co(NO3)3·6H2O, Ni(NO3)2·6H2O, Cr(NO3)3·9H2O, Cu(NO3)2·3H2O, Mo(NO3)3·5H2O, and FeSO4·7H2O are used as raw materials, with sodium borohydride as the boron source. The molar ratio of total metal elements to sodium borohydride is 1:

4. The raw materials and the boron source are respectively stirred in deionized water pre-purged with nitrogen or argon for 30–60 minutes using a mechanical stirrer at 300–500 rpm. The solution was continuously stirred and dissolved at a speed of r / min. The resulting salt solution was mixed with the boron source aqueous solution and then subjected to a reduction reaction. After separation by vacuum filtration, the filter cake was washed 3-6 times alternately with deionized water and anhydrous ethanol, each time for 1 minute. Finally, the filter cake was first frozen at -24 °C for 12 h, and then freeze-dried at a freezing temperature of -50 to -62 °C, a vacuum degree of 38 to 43 Pa, and a duration of 8 to 12 h until all ice crystals were observed to disappear.

2. The functional protective coating as described in claim 1, characterized in that: The high-entropy boride ceramic material has a particle size of 100~300 nm and a specific surface area of ​​10~100 m². 2 / g.

3. The functional protective coating as described in claim 1, characterized in that: The filler is nano-cerium oxide with a fluorite phase, a particle size of 20-30 nm, and a specific surface area of ​​10-20 m². 2 / g.

4. The functional protective coating as described in claim 1, characterized in that: The high-temperature resistant resin is at least one of perhydropolysilazane and polyureasilazane.

5. The functional protective coating as described in claim 1, characterized in that: The dispersant is Evcona AFCONA-4011.

6. The functional protective coating as described in claim 1, characterized in that: The defoamer is Evcona AFCONA-2027.

7. The functional protective coating as described in claim 1, characterized in that: The leveling agent is Evcona AFCONA-3034.

8. A method for preparing a functional protective coating as described in claim 1, characterized in that: The method first involves weighing the ingredients according to the specified proportions, then mixing and dispersing anhydrous ethanol, dispersant, defoamer, leveling agent, and high-temperature resistant resin, followed by adding functional pigments and fillers. The mixture is then stirred for 50-90 minutes using a high-speed disperser at a speed of 800-1200 r / min, and then dispersed and ground to a fineness of 20-35 μm using a sand mill or ball mill. Finally, the mixture is filtered through a 400-750 mesh screen to obtain the functional protective coating.

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