Rare earth doped composite solid solution energy-saving coating and preparation method thereof

Abstract

The invention relates to the technical field of industrial furnace coatings, in particular to a rare earth doped composite solid solution energy-saving coating and a preparation method thereof.The rare earth doped composite solid solution energy-saving coating is prepared from, by weight, 100 parts of powder base material, 0.1-1 part of dispersing agent and 100-200 parts of binding agent; wherein the powder base material comprises the following raw materials in parts by weight: 60-80 parts of lanthanum cerium carbonate, 3-5 parts of cerium carbonate and 10-20 parts of neodymium iron boron waste residues; the powder base material is prepared by mixing cerium lanthanum carbonate, cerium carbonate, neodymium iron boron waste residues and an auxiliary agent and then performing high-temperature calcination. The invention provides a rare earth doped composite solid solution energy-saving coating which is a novel energy-saving material applied to an industrial furnace, is sprayed on the surface of a refractory material of a high-temperature kiln to form a layer of hard ceramic glaze shell, and plays roles in protecting a furnace body, prolonging the service life of the kiln, reflecting infrared heat energy in a hearth and improving the combustion rate of the kiln.

Description

Technical Field

[0001] This invention belongs to the field of industrial furnace coating technology, specifically relating to a rare earth-doped composite solid solution energy-saving coating and its preparation method. Background Technology

[0002] Industrial kilns, hot blast stoves, and regenerators typically operate at temperatures above 1000℃. The thermal radiation and insulation properties of the refractory materials in the furnace body determine the kiln's thermal energy utilization efficiency. At room temperature, the emissivity of refractory materials is generally 0.6–0.8, decreasing to 0.4–0.5 as the furnace temperature rises. A significant amount of heat is transferred outward through the furnace wall, lowering the overall temperature of the internal materials, resulting in heat waste, increased costs, and even failure to reach the set temperature, leading to process failure. Currently, infrared radiation energy-saving coatings on the domestic market are mainly composed of a mixture of various metals and non-metals, generally exhibiting disadvantages such as poor high-temperature stability, short service life, unclear energy-saving and consumption-reducing effects, and high prices. Therefore, their usage rate in high-temperature kilns is low.

[0003] High-energy-consuming industries have entered a critical period of energy conservation, emission reduction, and carbon reduction. Technological upgrading is crucial for the survival and development of enterprises and is also an important goal of my country's industrial reform.

[0004] The steel, cement, glass, and ceramics industries, which are high-energy-consuming sectors, urgently need infrared radiation energy-saving coating materials that are inexpensive, have good high-temperature resistance, high infrared emissivity, and significant energy-saving and consumption-reducing effects. The renovation of existing high-temperature kilns and the construction of energy-saving high-temperature kilns will release huge market demand, and the market prospects are broad. Summary of the Invention To address the shortcomings of existing technologies, this invention provides a rare-earth-doped composite solid solution energy-saving coating, a novel energy-saving material for industrial furnaces. Sprayed onto the surface of refractory materials in high-temperature kilns, it forms a hard ceramic glaze shell, protecting the furnace body, extending its lifespan, reflecting infrared heat energy within the furnace chamber, and improving the furnace's combustion rate. Compared to existing energy-saving coatings, this rare-earth-doped composite solid solution energy-saving coating exhibits higher infrared normal emissivity and high-temperature stability, while also improving coating density and thermal shock resistance. This provides a feasible solution for traditional high-energy-consuming industries to upgrade their technology for energy conservation, emission reduction, and carbon reduction. Simultaneously, it addresses the issue of lanthanum and cerium product surplus, and is of great significance for the development and market application of lanthanum and cerium functional materials and products.

[0005] Specifically, the first aspect of this invention provides a rare earth-doped composite solid solution energy-saving coating, which comprises the following raw materials in parts by weight: 100 parts of powder base material, 0.1-1 parts of dispersant and 100-200 parts of binder; wherein, the powder base material comprises the following raw materials in parts by weight: 60-80 parts of lanthanum cerium carbonate, 3-5 parts of cerium carbonate and 10-20 parts of NdFeB waste residue; the powder base material is prepared by mixing lanthanum cerium carbonate, cerium carbonate, NdFeB waste residue and additives and then calcining at high temperature.

[0006] As a further explanation of the present invention, the additives, by weight, comprise 1-5 parts of manganese dioxide, 1-5 parts of copper oxide, and 3-5 parts of zircon powder.

[0007] As a further explanation of the present invention, the high-temperature calcination conditions are: heating to 1180~1280℃ and holding for 6~8 hours.

[0008] As a further explanation of the present invention, after the powder base material is calcined at high temperature, the following powder base material morphology modification process is also included: according to the weight parts, 100 parts and 0.1-1 parts of polymeric dispersant are stirred and dispersed evenly, and then 150-250 parts of the powder base material obtained by high temperature calcination are gradually added and ground. When the particle size of the powder in the suspension is less than 500nm, the grinding is stopped to obtain a modified slurry; the modified slurry is spray granulated, the microspheres are collected and sintered at high temperature to obtain spherical powder base material.

[0009] As a further explanation of the present invention, the pH value of the suspension is controlled at 8-10 during the grinding process, the inlet temperature of the granulator is controlled at 120°C during spray granulation, the high-temperature sintering temperature is 1000°C, and the time is 3 hours.

[0010] As a further explanation of the present invention, the powder base material needs to be pulverized to a particle size D90≤10μm before morphological modification, and the polymeric dispersant is ammonium polyacrylate.

[0011] A second aspect of this invention provides a method for preparing the above-mentioned rare earth-doped composite solid solution energy-saving coating, comprising the following steps: S1: Mix 30-70 parts water and 0.1-1 parts dispersant by weight, stir until uniform, then slowly add 100 parts powder base material and stir until uniform to obtain composite solid solution energy-saving slurry; S2: Under stirring, add 100-200 parts of binder to the composite solid solution energy-saving slurry, stir evenly, and obtain the rare earth doped composite solid solution energy-saving coating product.

[0012] As a further explanation of the present invention, in S1, during the mixing and stirring of water and dispersant, the stirring speed is 300-500 r / min and the stirring time is 5-15 min.

[0013] As a further explanation of the present invention, in S1, before the powder base material is added, the stirring speed is adjusted to 700-900 r / min, and after the base material is completely added, the stirring speed is adjusted to 900-1100 r / min, and high-speed dispersion is carried out for 15-30 min.

[0014] As a further explanation of the present invention, in S2, after the composite solid solution energy-saving slurry is added to the high-speed disperser, it is first stirred at a speed of 500-700 r / min. After stirring evenly, the speed is increased to 700-900 r / min, and 100-200 parts of binder are slowly added and stirred evenly to obtain the rare earth doped composite solid solution energy-saving coating product.

[0015] Compared with the prior art, the present invention has the following beneficial technical effects: 1. Energy saving and cost reduction: It offers excellent energy efficiency, reducing gas consumption, overall energy expenditure, carbon emissions, and energy costs. It also extends the service life of equipment and facilities, and prolongs the lifespan of kilns. During heating, a multiphase composite ceramic layer can be sintered into the inner lining of the inorganic kiln, effectively saving energy and extending the kiln's lifespan.

[0016] 2. Excellent performance: The rare-earth infrared radiation energy-saving coating prepared by this invention has a normal emissivity ε≥0.95 across the entire 1~22μm wavelength band, a heat storage rate increase of ≥30%, and an adhesion grade of 1. After a 1200℃ overheating test, the coating showed no chalking, cracking, blistering, or peeling.

[0017] 3. Simple to use and unrestricted by construction process: It can be used in various construction processes such as dip coating, spraying, brushing, roller coating, and curtain coating, depending on the working conditions.

[0018] 4. Solid Waste Resource Utilization: Utilizing rare earth and metal mineral waste and slag as raw materials enables the recovery and recycling of rare earth and transition metal elements, which is conducive to promoting resource conservation and intensive utilization, and building a resource-recycling industrial system. On the one hand, impurities enhance lattice distortion and form high-entropy structures; on the other hand, it achieves intensive reuse of resources, improves the utilization rate of waste rare earth and metal resources, turns waste into treasure, and reduces costs. This is of great significance for ensuring national resource security and promoting ecological civilization.

[0019] 5. Promoting the efficient and rapid development of the rare earth industry: High-abundance lanthanum and cerium products are heavily stockpiled due to weak demand in the consumer sector, with over 30,000 tons of lanthanum and cerium products remaining undeveloped and unutilized annually. Domestic demand for infrared radiation coatings is approximately 20,000 tons per year. The rare earth infrared radiation energy-saving coating of this invention contains over 60% lanthanum and cerium compounds. The industrial application and development of this invention can greatly promote the efficient utilization of lanthanum and cerium. Attached Figure Description

[0020] Figure 1 The flowchart illustrates the preparation process of rare earth-doped composite solid solution energy-saving coatings provided in this embodiment of the invention.

[0021] Figure 2 This is a morphology diagram of the powder matrix after morphology modification in Example 1 of the present invention.

[0022] Figure 3 The crystal phase diagrams of the calcined powder matrix materials in Examples 1-4 of this invention (from bottom to top: Examples 1, 2, 3, and 4), with □ in the diagram representing Ce. 0.9 Mn 0.1 O 1.9 ; ★: Na 0.5 Ca 1.6 La 0.8 Ce2(SiO4) 2.1 (PO4) 0.9 (OH); ○: La 0.827 Al 11.9 O 19.09 (Mn (Ni 0.5 V 1.5 ) O4. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] In the following examples, "parts" refers to parts by weight.

[0025] Example 1 A method for preparing a rare earth-doped composite solid solution energy-saving coating is provided, which comprises the following steps: a. Raw material pretreatment: The raw material is sieved through a 200-mesh sieve, with a residue of less than 5%, and then dried at 100℃ with a moisture content of less than 0.5%, and packaged for later use; b. Ingredient mixing: Weigh the following ingredients according to their weight percentage composition: 67% lanthanum cerium carbonate, 4% cerium carbonate, 18% neodymium iron boron waste residue, 1% manganese dioxide, 5% copper oxide, and 5% zircon powder, and mix all the above materials evenly. c. Calcination: The mixed powder is divided into portions according to three-quarters of the crucible capacity, evenly distributed and compacted. The muffle furnace is heated at 8℃ / min, held at 1240℃ for 7 hours, and then allowed to cool naturally to room temperature before removing the crucible to obtain the calcined product (true density 5.2 g / cm³). 3 ); d. Crushing and grinding: The calcined products are crushed and pulverized using a crusher and a pulverizer, and the material is ground to a particle size D90≤10μm using a grinding mill to obtain rare earth doped composite solid solution energy-saving coating powder base material; e. Morphology modification of powder base material: 1) According to the weight fraction, add 100 parts of deionized water and 0.2 parts of ammonium polyacrylate to the dispersion tank of the grinding mill. After stirring and dispersing evenly, turn on the grinding mill and gradually add 200 parts of powder base material. During the grinding process, the pH value of the suspension is controlled at 9. When the particle size of the powder in the suspension is less than 500nm, stop grinding. 2) Turn on the spray granulator and control the inlet temperature at 120℃. The slurry is uniformly fed into the spray granulator. The microspheres are collected in the collector and then sintered at 1000℃ for 3h to obtain spherical powder base material of rare earth doped composite solid solution energy-saving coating.

[0026] f. Slurry preparation: Add the prescribed amount of water (50% of the mass of the spherical powder base material) to the high-speed disperser, and stir at 400 r / min. Add dispersant BYK190 (0.2% of the mass of the spherical powder base material), and stir for 10 min. After the dispersant is evenly dispersed, adjust the speed to 800 r / min, and slowly add the prescribed amount of spherical powder base material. After the base material is completely added, adjust the speed to 1000 r / min and disperse at high speed for 20 min to obtain the slurry. g. Coating preparation: After adding the slurry to the high-speed disperser, stir it at a speed of 600 r / min. After stirring evenly, increase the speed to 800 r / min and slowly add the binder (the binder accounts for 150% of the mass of the spherical powder base material). Stir evenly to obtain the rare earth doped composite solid solution energy-saving coating product. h. Finished product packaging: Use a filling machine to package the finished paint product according to the required quantity of the packaging buckets; i. Construction and application: The rare earth doped composite solid solution energy-saving coating obtained in this embodiment can be applied by various construction processes such as dip coating, spraying, brushing, roller coating, and curtain coating.

[0027] Example 2 A method for preparing a rare earth-doped composite solid solution energy-saving coating is provided, which comprises the following steps: a. Raw material pretreatment: The raw material is sieved through a 200-mesh sieve, with a residue of less than 5%, and then dried at 100℃ with a moisture content of less than 0.5%, and packaged for later use; b. Ingredient mixing: Weigh the following ingredients according to their weight percentage composition: 60% lanthanum cerium carbonate, 5% cerium carbonate, 20% neodymium iron boron waste residue, 5% manganese dioxide, 5% copper oxide, and 5% zircon powder, and mix all the above materials evenly. c. Calcination: The mixed powder is divided into portions according to three-quarters of the crucible capacity, evenly distributed and compacted. The muffle furnace is heated at 10℃ / min, held at 1180℃ for 6 hours, and then allowed to cool naturally to room temperature before removing the crucible to obtain the calcined product (true density 5.0 g / cm³). 3 ); d. Crushing and grinding: The calcined products are crushed and pulverized using a crusher and a pulverizer, and the material is ground to a particle size D90≤10μm using a grinding mill to obtain rare earth doped composite solid solution energy-saving coating powder base material; e. Morphology modification of powder base material: 1) According to the weight fraction, add 100 parts of deionized water and 0.2 parts of ammonium polyacrylate to the dispersion tank of the grinding mill. After stirring and dispersing evenly, turn on the grinding mill and gradually add 200 parts of powder base material. During the grinding process, the pH value of the suspension is controlled at 9. When the particle size of the powder in the suspension is less than 500nm, stop grinding. 2) Turn on the spray granulator and control the inlet temperature at 120℃. The slurry is uniformly fed into the spray granulator. The microspheres are collected in the collector and then sintered at 1000℃ for 3h to obtain spherical powder base material of rare earth doped composite solid solution energy-saving coating.

[0028] f. Slurry preparation: Add water (50% of the mass of the spherical powder base material) to a high-speed disperser, and stir at 400 r / min. Add dispersant BYK190 (0.2% of the mass of the spherical powder base material), and stir for 10 min. After the dispersant is evenly dispersed, adjust the speed to 800 r / min, and slowly add the spherical powder base material according to the formula. After the base material is completely added, adjust the speed to 1000 r / min and disperse at high speed for 20 min to obtain the slurry. g. Coating preparation: After adding the slurry to the high-speed disperser, stir it at a speed of 600 r / min. After stirring evenly, increase the speed to 800 r / min and slowly add the binder (the binder accounts for 150% of the mass of the spherical powder base material). Stir evenly to obtain the rare earth doped composite solid solution energy-saving coating product. h. Finished product packaging: Use a filling machine to package the finished paint product according to the required quantity of the packaging buckets; i. Construction and application: The rare earth doped composite solid solution energy-saving coating obtained in this embodiment can be applied by various construction processes such as dip coating, spraying, brushing, roller coating, and curtain coating.

[0029] Example 3 A method for preparing a rare earth-doped composite solid solution energy-saving coating is provided, which comprises the following steps: a. Raw material pretreatment: The raw material is sieved through a 200-mesh sieve, with a residue of less than 5%, and then dried at 100℃ with a moisture content of less than 0.5%, and packaged for later use; b. Ingredient mixing: Weigh the following ingredients according to their weight percentage composition: 80% lanthanum cerium carbonate, 3% cerium carbonate, 10% neodymium iron boron waste residue, 2% manganese dioxide, 2% copper oxide, and 3% zircon powder, and mix all the above materials evenly. c. Calcination: The mixed powder is divided into portions according to three-quarters of the crucible capacity, evenly distributed and compacted. The muffle furnace is heated at 5℃ / min, held at 1280℃ for 8 hours, and then allowed to cool naturally to room temperature before removing the crucible to obtain the calcined product (true density 5.5 g / cm³). 3 ); d. Crushing and grinding: The calcined products are crushed and pulverized using a crusher and a pulverizer, and the material is ground to a particle size D90≤10μm using a grinding mill to obtain rare earth doped composite solid solution energy-saving coating powder base material; e. Morphology modification of powder base material: 1) According to the weight fraction, add 100 parts of deionized water and 0.2 parts of ammonium polyacrylate to the dispersion tank of the grinding mill. After stirring and dispersing evenly, turn on the grinding mill and gradually add 200 parts of powder base material. During the grinding process, the pH value of the suspension is controlled at 9. When the particle size of the powder in the suspension is less than 500nm, stop grinding. 2) Turn on the spray granulator and control the inlet temperature at 120℃. The slurry is uniformly fed into the spray granulator. The microspheres are collected in the collector and then sintered at 1000℃ for 3h to obtain spherical powder base material of rare earth doped composite solid solution energy-saving coating.

[0030] f. Slurry preparation: Add the prescribed amount of water (50% of the mass of the spherical powder base material) to a high-speed disperser, and stir at 400 r / min. Add dispersant BYK190 (0.2% of the mass of the spherical powder) and stir for 10 min. After the dispersant is evenly dispersed, adjust the speed to 800 r / min and slowly add the prescribed amount of spherical powder base material. After the base material is completely added, adjust the speed to 1000 r / min and disperse at high speed for 20 min to obtain the slurry. g. Coating preparation: After adding the slurry to the high-speed disperser, stir it at a speed of 600 r / min. After stirring evenly, increase the speed to 800 r / min and slowly add the binder (the binder accounts for 150% of the mass of the spherical powder). Stir evenly to obtain the rare earth doped composite solid solution energy-saving coating product. h. Finished product packaging: Use a filling machine to package the finished paint product according to the required quantity of the packaging buckets; i. Construction and application: The rare earth doped composite solid solution energy-saving coating obtained in this embodiment can be applied by various construction processes such as dip coating, spraying, brushing, roller coating, and curtain coating.

[0031] Example 4 A method for preparing a rare earth-doped composite solid solution energy-saving coating is provided, which comprises the following steps: a. Raw material pretreatment: The raw material is sieved through a 200-mesh sieve, with a residue of less than 5%, and then dried at 100℃ with a moisture content of less than 0.5%, and packaged for later use; b. Ingredient mixing: Weigh the following ingredients according to their weight percentage composition: 72% lanthanum cerium carbonate, 3% cerium carbonate, 15% neodymium iron boron waste residue, 5% manganese dioxide, 1% copper oxide, and 4% zircon powder, and mix all the above materials evenly. c. Calcination: The mixed powder is divided into portions according to three-quarters of the crucible capacity, evenly distributed and compacted. The muffle furnace is heated at 7℃ / min, held at 1260℃ for 8 hours, and then allowed to cool naturally to room temperature before removing the crucible to obtain the calcined product (true density 5.3 g / cm³). 3 ); d. Crushing and grinding: The calcined products are crushed and pulverized using a crusher and a pulverizer, and the material is ground to a particle size D90≤10μm using a grinding mill to obtain rare earth doped composite solid solution energy-saving coating powder base material; e. Morphology modification of powder base material: 1) According to the weight fraction, add 100 parts of deionized water and 0.2 parts of ammonium polyacrylate to the dispersion tank of the grinding mill. After stirring and dispersing evenly, turn on the grinding mill and gradually add 200 parts of powder base material. During the grinding process, the pH value of the suspension is controlled at 9. When the particle size of the powder in the suspension is less than 500nm, stop grinding. 2) Turn on the spray granulator and control the inlet temperature at 120℃. The slurry is uniformly fed into the spray granulator. The microspheres are collected in the collector and then sintered at 1000℃ for 3h to obtain spherical powder base material of rare earth doped composite solid solution energy-saving coating.

[0032] f. Slurry preparation: Add the prescribed amount of water (50% of the mass of the spherical powder base material) to a high-speed disperser, and stir at 400 r / min. Add dispersant BYK190 (0.2% of the mass of the spherical powder base material), and stir for 10 min. After the dispersant is evenly dispersed, adjust the speed to 800 r / min, and slowly add the prescribed amount of base material. After the base material is completely added, adjust the speed to 1000 r / min and disperse at high speed for 20 min to obtain the slurry. g. Coating preparation: After adding the slurry to the high-speed disperser, stir it at a speed of 600 r / min. After stirring evenly, increase the speed to 800 r / min and slowly add the binder (the binder accounts for 150% of the mass of the spherical powder base material). Stir evenly to obtain the rare earth doped composite solid solution energy-saving coating product. h. Finished product packaging: Use a filling machine to package the finished paint product according to the required quantity of the packaging buckets; i. Construction and application: The rare earth doped composite solid solution energy-saving coating provided in this embodiment can be applied by various construction processes such as dip coating, spraying, brushing, roller coating, and curtain coating.

[0033] The performance test results of the rare earth doped composite solid solution energy-saving coatings obtained in the above embodiments are shown in Table 1 below.

[0034] Table 1 Performance test results of rare earth doped composite solid solution energy-saving coatings project Test Standards Performance test results State in the container GB 9755-2018 There are no lumps, and the mixture becomes homogeneous after stirring. Drying time HG / T 4565-2013 Surface dry, ≤2h Adhesion GB / T 9286-1998 1 Antioxidant properties HG / T 4565-2013 No corrosion, no obvious oxidation color thermal shock resistance GB / T 30873-2014 ≥10 times hardness Vickers hardness tester ≥5H Bond strength Test using the 100-grid knife method The coating is free from chalking, cracking, blistering, and peeling. Infrared normal total emissivity GJB 5023.2-2003 ≥0.95 Heat storage rate GB / T31934-2015 ≥30% Viscosity (calculated in terms of outflow time) Suspension cup viscometer ≤16 seconds Comparative Example 1: Unlike Example 1, in step b, the content of lanthanum cerium carbonate is >80% or <60%.

[0035] The coating performance test results are as follows: its infrared normal total emissivity is <0.90, and the heat storage rate improvement is <20%. This may be because when lanthanum and cerium carbonate content is >80%, during the high-temperature sintering process to form a high-emissivity high-temperature solid solution, the lanthanum and cerium carbonate component exceeds the standard and exists in the material in the form of lanthanum and cerium oxide, reducing the overall emissivity of the material. The decrease in emissivity will lead to a decrease in the material's heat absorption and release capacity, and thus a decrease in the heat storage rate. When lanthanum and cerium carbonate content is <60%, during the high-temperature sintering process to form a high-emissivity high-temperature solid solution, the remaining components exceed the standard, and the emissivity of each individual oxide material is lower than that of the high-temperature continuous solid solution synthesized in this patent, thus reducing the overall emissivity of the material. The decrease in emissivity will lead to a decrease in the material's heat absorption and release capacity, and thus a decrease in the heat storage rate.

[0036] Comparative Example 2: Unlike Example 1, in step c, the calcination temperature of the coating powder is set to <1180℃ or >1280℃.

[0037] The coating performance was tested as follows: true density of powder < 5.0 g / cm³ 3 Or >5.5g / cm 3 The coating with the optimal specifications shown in the table above could not be prepared. This is likely because at temperatures below 1180℃, the initial equilibrium temperature for full sintering required by this patent cannot be reached. The powder cannot receive sufficient energy, resulting in incomplete sintering and inability to achieve crystal phase reconstruction. Therefore, according to the process described in this patent, a dense rare-earth-based high-temperature solid solution, i.e., <5.0 g / cm³, cannot be obtained. 3 This reduces the service life of the final coating; at temperatures above 1280°C, the powder sintering degree is too high, and according to the process of this patent, the rare earth-based high-temperature solid solution obtained is severely liquefied and cannot be produced (a. the powder and the container crucible containing the powder undergo a high-temperature chemical reaction, resulting in the inability to separate them, and ultimately no usable sintered material is obtained).

[0038] Comparative Example 3: Unlike Example 1, cerium carbonate is omitted in step b.

[0039] In the "g. Coating Preparation" process, the coating tends to become too thick and the curing time is shortened, making it unsuitable for industrial field application and resulting in an unqualified color (blackish-gray). This may be because cerium carbonate, during its transformation into cerium oxide through high-temperature sintering, has a function of fixing atoms, preventing the precipitation of transition element ions, and further avoiding the room-temperature reaction between the precipitated ions and the binder.

[0040] Comparative Example 4: The difference from Example 1 is that the components manganese dioxide, copper oxide, and zircon powder (any one, any combination of two, or all three) are omitted in step b.

[0041] The coating performance test results are as follows: its infrared normal emissivity is <0.85, and its heat storage rate is increased by <18%.

[0042] Comparative Example 5: The difference from Example 1 is that the NdFeB waste residue component is omitted in step b.

[0043] The NdFeB waste residue contains a large amount of Fe2O3 (72.39%) and SiO2 (7.161%) elements. The ferrosilicon elements enter the crystal lattice of lanthanum oxide and cerium oxide, which helps to lower the sintering temperature and increase the rigidity and hardness of the material. If this component is omitted, then: in the "c. calcination" process stage, a qualified continuous solid solution cannot be formed below 1280℃; in the "d. crushing and grinding" process stage, there is severe adhesion to the inner wall of the equipment, making production impossible. Furthermore, if the NdFeB waste residue content is increased, the sintering temperature becomes too low, leading to a decrease in the material's refractoriness (<1180℃), affecting the high-temperature application starting temperature of the coating.

[0044] Comparative Example 6 Unlike Example 1, steps c, calcination, and d, crushing and grinding are omitted, and the mixed powder is directly subjected to morphological modification treatment.

[0045] The coating performance test results are as follows: its infrared normal emissivity is <0.90, and its heat storage rate improvement is <20%. Without high-temperature calcination, a rare earth-based high-temperature solid solution cannot be formed, thus the emissivity and heat storage rate cannot meet the standards.

[0046] Comparative Example 7 The difference from Example 1 is that step e, the process of modifying the morphology of the powder matrix, is omitted.

[0047] Comparative Example 7 cannot yield an energy-saving coating suitable for practical market application. The rare-earth-doped composite solid solution energy-saving coating spherical powder obtained through "step e" is easier to disperse during the "f, slurry preparation" process. If "step e" is omitted, it will lead to excessive stratification and sedimentation of the slurry, which will affect the coating effect in the "i, construction and use" process. Ultimately, this will result in problems such as peeling, blistering, and cracking at ≥1200℃, making it impossible to guarantee the long-term use of the coating.

[0048] In summary, the rare earth-doped composite solid solution energy-saving coating provided by this invention uses rare earth compounds such as lanthanum and cerium as the main raw materials. Rare earth atoms have a compact electronic structure, high valence, variable valence, large radius, strong polarization, and active chemical properties. The inner 4f electrons of rare earth elements are shielded by the outer 5s and 5p electrons, exhibiting a localization effect. The outermost electron configuration, which determines the properties of the element, forms the conduction band with 4f and 5d electrons. The localization and incomplete filling of 4f electrons give rare earths unique optical, magnetic, and oxygen storage / release properties. By introducing rare earth elements lanthanum and cerium to form solid solutions with transition metal oxides, the larger ionic radius of rare earth elements makes it easier to cause lattice distortion during sintering, increasing lattice vibration activity and shifting infrared spectral lines towards shorter wavelengths. This improves the infrared emissivity and high-temperature stability of the material in the 1–5 μm band, making it more suitable for high-temperature applications and easier for the heated body to absorb and utilize the heat (according to Kirchhoff's law, the relationship between emissivity and heat absorption / release capacity is εabsorbed = εreleased, meaning that the heat absorption / release capacity of a material is closely related to its emissivity; the higher the emissivity, the stronger its heat absorption / release capacity and the stronger its heat storage capacity).

[0049] This invention utilizes high-temperature solid solution to form high-entropy compounds, increasing the entropy value of the material and thus improving its thermal stability, mechanical properties, and heat storage capacity. (Entropy is a macroscopic quantity, representing the collective property of a large number of microscopic ions constituting a system. It refers to the ability to do work, including the entropy contributed by molecular translation, vibration, rotation, electronic motion, and nuclear spin motion. The basic principle of the high-entropy solid solution strengthening effect is that by adding high-entropy elements, the entropy value of the material can be increased, thereby improving its thermal stability and mechanical properties.)

[0050] From a manufacturing process perspective, simply mixing various transition metal oxides cannot alter the material's microstructure, nor can it overcome the limitations of multiphonon radiation and absorption mechanisms to improve the material's full-band infrared radiation performance. Therefore, this invention employs high-temperature calcination to alter the microstructure and phase composition of the powder matrix, thereby strengthening the electron transition radiation mechanism of free carriers and impurity energy levels. Furthermore, by adding trace amounts of additives (manganese dioxide, copper oxide, zircon powder), the periodic potential field of the crystal lattice is locally disrupted. In these localized regions with additives, the energy states of electrons differ from those in other parts of the crystal, resulting in impurity energy levels within the electronic band gap. This provides favorable conditions for electron and hole transitions in the valence band, increasing the free carrier concentration in the crystal and thus improving the infrared absorption of free carriers related to infrared absorption, ultimately enhancing the crystal's infrared absorption performance. At the same time, the replacement of atoms in the crystal by impurities disrupts the lattice translational symmetry of the crystal. In the local region centered on the impurity, its lattice constant and atomic mass are different from other parts, causing the spectral absorption band of the impurity's local lattice vibration to shift towards the short-wave infrared direction, thereby improving the near-infrared spectral absorption characteristics of the crystal and ultimately improving the full-band infrared radiation performance of the product.

[0051] It should be noted that, in this document, terms such as “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0052] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A rare earth-doped composite solid solution energy-saving coating, characterized in that, The raw materials comprise the following parts by weight: 100 parts of powder base material, 0.1-1 parts of dispersant, and 100-200 parts of binder; wherein the powder base material comprises the following parts by weight: 60-80 parts of lanthanum-cerium carbonate, 3-5 parts of cerium carbonate, and 10-20 parts of NdFeB waste residue; the powder base material is prepared by mixing lanthanum-cerium carbonate, cerium carbonate, NdFeB waste residue, and additives and then calcining at high temperature.

2. The rare earth-doped composite solid solution energy-saving coating as described in claim 1, characterized in that, According to the weight parts, the additives contain 1-5 parts of manganese dioxide, 1-5 parts of copper oxide, and 3-5 parts of zircon powder.

3. The rare earth-doped composite solid solution energy-saving coating as described in claim 1, characterized in that, The high-temperature calcination conditions are as follows: heat to 1180~1280℃ and hold for 6~8 hours.

4. The rare earth-doped composite solid solution energy-saving coating as described in claim 1, characterized in that, After high-temperature calcination, the powder matrix material also includes the following powder matrix material morphology modification process: According to the weight ratio, 100 parts and 0.1-1 parts of polymeric dispersant are stirred and dispersed evenly, and then 150-250 parts of powder base material obtained by high temperature calcination are gradually added and ground. When the particle size of the powder in the suspension is less than 500nm, the grinding is stopped to obtain the modified slurry. The modified slurry was spray-granulated, and the collected microspheres were sintered at high temperature to obtain spherical powder matrix.

5. The rare earth-doped composite solid solution energy-saving coating as described in claim 4, characterized in that, During the grinding process, the pH value of the suspension is controlled at 8-10. During spray granulation, the inlet temperature of the granulator is controlled at 120℃, and the high-temperature sintering temperature is 1000℃ for 3 hours.

6. The rare earth-doped composite solid solution energy-saving coating as described in claim 4, characterized in that, Before morphological modification, the powder base material needs to be pulverized to a particle size D90≤10μm, and the polymeric dispersant is ammonium polyacrylate.

7. A method for preparing a rare earth-doped composite solid solution energy-saving coating according to any one of claims 1 to 6, characterized in that, Includes the following steps: S1: Mix 30-70 parts water and 0.1-1 parts dispersant by weight, stir until uniform, then slowly add 100 parts powder base material and stir until uniform to obtain composite solid solution energy-saving slurry; S2: Under stirring, add 100-200 parts of binder to the composite solid solution energy-saving slurry, stir evenly, and obtain the rare earth doped composite solid solution energy-saving coating product.

8. The preparation method according to claim 7, characterized in that, In S1, during the mixing and stirring of water and dispersant, the stirring speed is 300-500 r / min and the stirring time is 5-15 min.

9. The preparation method according to claim 7, characterized in that, In S1, before adding the powder base material, adjust the stirring speed to 700-900 r / min. After the base material is completely added, adjust the stirring speed to 900-1100 r / min and disperse at high speed for 15-30 min.

10. The preparation method according to claim 7, characterized in that, In S2, after adding the composite solid solution energy-saving slurry to the high-speed disperser, it is first stirred at a speed of 500-700 r / min. After stirring evenly, the speed is increased to 700-900 r / min, and 100-200 parts of binder are slowly added and stirred evenly to obtain the rare earth doped composite solid solution energy-saving coating product.

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