Atomic-scale complex-phase high-entropy oxide coating material and preparation and application thereof

Abstract

The invention relates to the technical field of high-temperature-resistant composite coatings, in particular to an atomic-scale complex-phase high-entropy oxide coating material and preparation and application thereof. The preparation method comprises the following steps: firstly, dissolving Mg2AlO4 and transition metal alloy powder, mixing, and carrying out ball milling to obtain spinel-structure high-entropy oxide precursor powder; then carrying out freeze drying treatment on the spinel structure high-entropy oxide precursor powder, and then carrying out sintering treatment to obtain spinel structure high-entropy oxide powder; dissolving metal salt, and blending to obtain a mixed solution; and finally, uniformly mixing the spinel-structure high-entropy oxide powder with the mixed solution, carrying out solvothermal reaction, and carrying out post-treatment to obtain the atomic-scale complex-phase high-entropy oxide coating material. The coating material provided by the invention has high-stability infrared radiation performance and can resist high-temperature oxidation.

Description

Technical Field

[0001] The present invention relates to the technical field of high-temperature resistant composite coatings, and in particular to an atomic-level multiphase high-entropy oxide coating material and its preparation and application. Background Art

[0002] With the rapid development of science and technology and the continuous expansion of industrial applications, the requirements for material performance are increasing day by day. Traditional materials often cannot meet the stringent requirements of high temperature resistance, high strength, corrosion resistance, etc. under extreme working conditions. Currently, in the field of aerospace, when an aircraft is cruising at an altitude of 22km at 8 times the speed of sound, the temperature of local areas such as the aircraft nose cone, wing leading edge, and air inlet lip will reach 1500℃ (Li Chongjun. Analysis of the structure of C / C thermal protection coating of X-43A hypersonic aircraft [J]. High-tech Fibers and Applications, 2015, 40(04): 26-30+43); in industrial kilns, high-emissivity infrared radiation coatings are applied to the surface of the furnace wall to enhance the radiation heat transfer inside the furnace body. In industrial production such as high-temperature kilns, there is also a demand for the application of materials at high temperatures of 1500℃.

[0003] At present, silicon carbide (SiC) and molybdenum disilicide (MoSi2) have become widely used materials in the high-temperature infrared field due to their relatively excellent performance. SiC has excellent mechanical strength, high-temperature oxidation resistance, and thermal shock resistance, but SiC series infrared radiation coatings will cause emissivity to decay due to high-temperature oxidation and are easily corroded by water vapor and molten salts (Xiao S, Li J, Huang P, et al. Evaluation of environmental barrier coatings: Areview[J]. International Journal of Applied Ceramic Technology, 2023, 20(4): 2055-2076.), resulting in them being used only in kilns with lower temperatures or reducing atmospheres. MoSi2 has a high melting point (Tm = 2293K), high modulus and excellent oxidation resistance (Mao J, Ding S, Li Y, et al. Preparation and investigation of MoSi2 / SiC coating with high infrared emissivity at high temperature [J]. Surface and Coatings Technology, 2019, 358: 873-878.). Currently, several MoSi2-based coating systems have been developed as high-emissivity coatings on fiber substrates, such as MoSi2-borosilicate glass coatings and MoSi2-aluminoborosilicate glass coatings. However, the emissivity of MoSi2 coatings in the near-infrared region still needs to be improved, and the bonding strength of the brush-coated coating decreases with the crystallization of the amorphous binder. In recent years, MoSi2-based / SiC infrared radiation materials have gradually become a research hotspot. Studies have shown that SiC can expand the spectral absorption band of MoSi2 from the visible light region to the near-infrared region, making up for the low emissivity of MoSi2 coating in the near-infrared region. The infrared emissivity of this material can reach 0.908 in an environment of 1400°C (Mao J, Ding S, Li Y, et al. Preparation and investigation of MoSi2 / SiC coating with high infrared emissivity at high temperature[J]. Surface and Coatings Technology, 2019, 358: 873-878.), making it a promising infrared radiation material.However, the thermal expansion coefficients of MoSi2 and SiC are quite different, which can easily lead to cracking or peeling of the coating (Wang Y, Su D, Ji H, et al. Gradient structure high emissivity MoSi2-SiO2-SiOC coating for thermal protective application[J]. Journal of Alloys and Compounds, 2017, 703: 437-447.). Moreover, as the temperature increases, MoSi2 is easily oxidized at high temperatures, resulting in a decrease in its infrared radiation performance, which limits its application as a high-temperature thermal barrier coating.

[0004] Faced with the above-mentioned difficulties and the demand for high-temperature infrared radiation materials, high-entropy oxides have become a research hotspot due to their excellent high-temperature resistance and high stability (Tomboc GM, Zhang X, Choi S, et al. Stabilization, characterization, and electrochemical applications of high-entropy oxides: critical assessment of crystal phase–properties relationship [J]. Advanced Functional Materials, 2022, 32 (43): 2205142.). Currently, existing high-temperature resistant and highly stable high-entropy oxide coatings are mainly prepared by solid-phase method or physical vapor deposition method (patent CN116043164A), but these two conventional preparation methods are generally prone to problems such as component segregation and thermal expansion mismatch. The preparation of high-entropy oxides by combining mechanical wet grinding and solid-phase synthesis can ensure that the metal elements are fully mixed and the production efficiency is high (patent CN117902879A), but the low-boiling point elements have high surface activity after wet grinding, which will increase the volatility during sintering and easily cause the grain boundary brittleness of the grains to increase. In addition, the current research focus of high-entropy oxide materials with high-temperature resistance and high-stability infrared radiation performance is mainly concentrated in the 2-22μm band. In this band, the infrared emissivity can reach above 0.88 (patents CN113354394A, CN118598650A). However, there is little research on the infrared emissivity performance below the 2μm band, which limits the application of high-entropy oxide materials in a wider band range. The infrared emissivity of the band below 2μm is still in urgent need of research and improvement. Previously, Sun Geting and others studied and prepared spinel-perovskite dual-phase ceramics (patent CN117902879A), introduced high-temperature resistant rare earth elements and performed high-entropy design at the A position. Its structure is stable and still has a high infrared emissivity after long-term high-temperature calcination. The maximum operating temperature can reach 1600℃. The emissivity reaches above 0.9 in the 2-22 μm band, while the absorptivity reaches above 0.87 in the 0.3-2.5 μm band; however, its preparation method adopts mechanical wet grinding and solid-state combination method, and there are still deficiencies in the preparation method.

[0005] Therefore, innovative preparation methods are needed to combine the excellent properties of high-entropy oxides to develop a high-entropy oxide coating material that is resistant to high temperatures, highly stable, has excellent infrared radiation performance, and has greatly improved oxidation resistance and service time. Summary of the Invention

[0006] In order to address the shortcomings of existing high-temperature thermal barrier coatings, the purpose of the present invention is to provide an atomic-level complex phase high-entropy oxide coating material and its preparation and application. The present invention first dissolves Mg2AlO4 and transition metal alloy powder and mixes them, and ball mills them to obtain a spinel structure high-entropy oxide precursor powder; then freeze-dries the spinel structure high-entropy oxide precursor powder and then sinters it to obtain a spinel structure high-entropy oxide powder; dissolves the metal salt and blends them to obtain a mixed solution; finally, the spinel structure high-entropy oxide powder and the mixed solution are mixed to perform a solvent thermal reaction, and then post-processed to obtain an atomic-level complex phase high-entropy oxide coating material. The coating material provided by the present invention has highly stable infrared radiation performance and can withstand high-temperature oxidation.

[0007] Currently, high-entropy oxides primarily include rock salt, fluorite, perovskite, and spinel structures. Among these, spinel and fluorite high-entropy oxides exhibit superior thermal stability. Spinel high-entropy oxides utilize impurity elements to replace atoms in the original lattice, causing lattice distortion and disrupting the original periodicity, promoting the absorption of lattice vibrations and thus exhibiting higher infrared emissivity. Fluorite high-entropy oxides, through the synergistic effect of multiple components, increase the free carrier concentration in the conduction band or valence band, resulting in higher reflectivity. The present invention first prepares spinel high-entropy oxide by a high-energy ball milling method, promotes atomic-level mixing of multi-metals, and forms a lattice distortion and a high-entropy stable structure; then innovatively adopts an organic solvent thermal synthesis method to in situ synthesize nano-high-entropy fluorite structure oxide containing transition metal elements and multi-rare earth elements on the surface of the spinel high-entropy oxide powder, thereby forming a composite ceramic with an outer shell fluorite structure covering an inner spinel structure, which can ensure high emissivity and high reflectivity while having better ultra-high temperature thermal stability, thereby achieving a significant improvement in oxidation resistance service time and molten salt corrosion resistance.

[0008] The purpose of the present invention can be achieved by the following technical solutions:

[0009] The first object of the present invention is to provide a method for preparing an atomic-level multiphase high entropy oxide coating material, comprising the following steps:

[0010] (S1) dissolving Mg2AlO4 and transition metal alloy powder, mixing them, and ball milling them to obtain a spinel structure high entropy oxide precursor powder;

[0011] The transition metal is selected from two or more of Co, Cr, Fe, Ni or Ta;

[0012] (S2) freeze-drying the spinel structure high entropy oxide precursor powder prepared in step (S1), and then sintering it to obtain a spinel structure high entropy oxide powder;

[0013] dissolving the metal salts and blending them to obtain a mixed solution;

[0014] The metal is selected from five or more of Zr, Ti, Hf, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu or Sc;

[0015] (S3) The spinel structure high entropy oxide powder prepared in step (S2) is mixed with the mixed solution prepared in step (S2) to perform a solvent thermal reaction, thereby realizing the in situ synthesis of a fluorite structure high entropy nano-oxide shell layer on the surface of the spinel high entropy oxide; then, the liquid phase is separated by precipitation and centrifugation, and the liquid phase is gelled after washing, and dried to obtain an atomic-level complex phase high entropy oxide coating material: spinel / fluorite structure complex phase ceramic oxide powder.

[0016] In one embodiment of the present invention, in step (S1), the molar ratio of Mg2AlO4 to transition metal alloy powder is 1:1 to 5:1;

[0017] The ball milling process is carried out under an inert gas atmosphere (preferably, the inert gas is nitrogen to prevent oxidation or contamination), the ball milling medium is a mixture of zirconia balls with diameters of 3 to 4 mm, 6 to 7 mm, and 9 to 10 mm (preferably, the ball milling medium is an equal proportion of zirconia balls with diameters of 3 mm, 6 mm, and 10 mm); the ball-to-material ratio is 10 to 20:1 (a high ratio accelerates refinement), the ball milling speed is 2000 to 3000 revolutions per minute, and the ball milling time is 8 to 16 hours.

[0018] In one embodiment of the present invention, the particle size of Mg2AlO4 is 1 to 5 μm.

[0019] In one embodiment of the present invention, in step (S2),

[0020] The metal salt is dissolved in a solution of one or a mixture of two of methanol, N,N-dimethylformamide, ethylene glycol, isopropyl alcohol, toluene or xylene;

[0021] During the freeze-drying process, the temperature is -80 to -20°C and the time is 2 to 8 hours;

[0022] During the sintering process, the temperature is 1200-1500°C and the time is 2-10 hours;

[0023] In the mixed solution, the molar ratio of each metal is the same.

[0024] In one embodiment of the present invention, in step (S3), the mass ratio of the spinel structure high entropy oxide powder to the mixed solution is 1:9 to 4:6;

[0025] During the solvent thermal reaction, the temperature is 220-280°C and the time is 24-72 hours.

[0026] In one embodiment of the present invention, the precipitate of the synthetic product is centrifuged to separate the liquid phase, which is washed twice with chloroform and then washed with ether to perform a gelation process, and then the gel is dried at 80°C.

[0027] The second purpose of the present invention is to provide an atomic-level multiphase high entropy oxide coating material prepared by the above method.

[0028] The third object of the present invention is to provide an application of an atomic-level multiphase high-entropy oxide coating material in the preparation of an atomic-level multiphase high-entropy oxide coating.

[0029] A fourth object of the present invention is to provide a method for preparing an atomic-level multiphase high-entropy oxide coating, comprising the following steps:

[0030] (A1) mixing an atomic-level multiphase high entropy oxide coating material and a film-forming agent to obtain a mixed slurry;

[0031] (A2) coating the mixed slurry prepared in step (A1) on the pretreated substrate surface, drying it, and performing a stepwise temperature-increasing calcination treatment to obtain an atomic-level multiphase high-entropy oxide coating.

[0032] In one embodiment of the present invention, in step (A1), the film-forming agent is selected from one or two of polyvinyl alcohol (PVA), polyethylene glycol (PEG), glutinous rice starch and chitosan;

[0033] In the mixed slurry, the mass percentage of the atomic-level multiphase high entropy oxide coating material is 60% to 75%;

[0034] In step (A2), the coating is selected from one of spraying, rolling or brushing;

[0035] During the drying process, the temperature is 20-40°C and the time is more than 24 hours;

[0036] The step-by-step heating calcination process includes the first stage calcination process, the second stage calcination process, the third stage calcination process and the fourth stage calcination process.

[0037] During the first stage of calcination, the temperature is 550-650°C and the holding time is 2-8 hours;

[0038] During the second stage of calcination, the temperature is 850-950°C and the holding time is 2-6 hours;

[0039] During the third stage of calcination, the temperature is 1100-1200°C and the holding time is 2-6 hours;

[0040] During the fourth stage of calcination, the temperature is 1400-1600°C and the holding time is 6-12 hours.

[0041] Preferably, during the first stage calcination treatment, the temperature is 600°C and the holding time is 4 hours;

[0042] During the second stage of calcination, the temperature was 900°C and the holding time was 2h;

[0043] During the third stage of calcination treatment, the temperature was 1150°C and the holding time was 2h;

[0044] During the fourth stage of calcination, the temperature is 1400°C and the holding time is 2h.

[0045] In one embodiment of the present invention, in step (A1), the mixed slurry contains 0.5 to 15% by mass of a commercial functional additive for adjusting the uniformity of the mixed slurry;

[0046] The commercial functional additives are anti-settling agents, defoaming agents and dispersants;

[0047] In step (A2), the pretreated substrate is obtained by the following method:

[0048] Use sandpaper to polish the surface of the substrate (metal or refractory brick substrate) to remove pollutants or oxide layers, and then blow the surface with high-speed airflow for 3 to 5 minutes;

[0049] The thickness of each coating layer is 35-50μm. If you apply multiple coats, you need to wait until the surface of the previous coat is dry before applying the next coat.

[0050] The step-by-step heating calcination process has a heating rate of ≤20℃ / h. It can be completed in an inert gas atmosphere (full oxygen combustion kiln) to avoid oxidation reaction that damages the coating components. After the step-by-step heating calcination process is completed, it can be cooled with the furnace or by cooling.

[0051] The fifth object of the present invention is to provide an atomic-level multiphase high entropy oxide coating prepared by the above method.

[0052] The sixth object of the present invention is to provide an atomic-level multiphase high entropy oxide coating for use in the field of ultra-high temperature thermal insulation and energy saving.

[0053] Compared with the prior art, the present invention has the following beneficial effects:

[0054] (1) Traditional methods make it difficult to achieve atomic-level uniformity in the preparation of ceramic materials containing more than five elements of transition metals and rare earth elements with large differences in atomic radius, and are unable to give full play to the advantages of each element and the synergistic advantages of multiple elements. The present invention sintered the spinel-structured high-entropy oxide precursor powder and used an organic solvent thermal synthesis method to in-situ prepare high-entropy fluorite-structured nanoshells on the surface of the spinel powder. This preparation method achieves uniform dispersion of the metal oxide precursor through liquid phase reaction, avoiding local component segregation caused by uneven mechanical mixing in the traditional solid phase method; the nucleation rate and crystal growth kinetics can be precisely controlled by adjusting the temperature, pressure and solvent polarity; in addition, the reaction temperature of the solvent thermal method is usually lower than that of the traditional high-temperature solid phase method, which can significantly reduce energy consumption and equipment costs.

[0055] (2) The core-shell composite ceramic high entropy oxide in the present invention has better high-temperature thermal stability due to its spinel structure, and has a high emissivity that can reach above 0.85, and can also be maintained in the 0.8-2 μm band, which makes up for the insufficient temperature resistance of existing high-reflection and emissivity materials; in addition, the fluorite structure high entropy oxide has a high reflectivity. The present invention uses spinel structure high entropy oxide and fluorite structure high entropy composite oxide to prepare a coating, which improves the infrared radiation performance of the coating from the two perspectives of high emissivity and high reflectivity, thereby greatly improving the service life and energy-saving efficiency in ultra-high temperature kiln environments above 1600°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 This is the XRD pattern of the spinel structure high entropy oxide prepared in Example 1;

[0057] Figure 2 This is a reflectivity curve of the spinel structure high entropy oxide prepared in Example 1;

[0058] Figure 3 The XRD pattern of the spinel / fluorite structured composite high entropy oxide prepared in Example 1;

[0059] Figure 4 This is a graph showing the emissivity of the spinel / fluorite composite high-entropy oxide prepared in Example 1;

[0060] Figure 5 These are optical microscopic photographs of the morphology and blackness value (blackness value 1 = emissivity 1) of the spinel / fluorite multiphase structure high entropy oxide sintered block prepared in Example 1 before and after heat treatment;

[0061] Figure 6 This is a light microscopic photograph of the atomic-level multiphase high-entropy oxide coating prepared in Example 2 after heat treatment;

[0062] Figure 7This is the emissivity curve of the oxide coating material prepared in Comparative Example 1. DETAILED DESCRIPTION

[0063] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0064] In the following examples, unless otherwise specified, all reagents used are commercially available reagents, and all detection means and methods used are conventional detection means and methods in the art.

[0065] Example 1

[0066] This embodiment provides a method for preparing an atomic-level multiphase high-entropy oxide coating material, as follows:

[0067] (S1) dispersing Mg2AlO4 and transition metal alloy powder (Cr powder, Fe powder, and Ni powder in equal molar ratios) in 100 parts of isopropanol and mixing them uniformly, wherein the mass fraction of Mg2AlO4 is 50 parts and the mass fraction of the transition metal alloy powder is 50 parts, and then preparing a spinel structure high entropy oxide precursor powder by planetary high energy ball milling;

[0068] The milling process was carried out under nitrogen atmosphere at a speed of 2500 rpm for 10 h.

[0069] (S2) freeze-drying the spinel structure high entropy oxide precursor powder prepared in step (S1) (-80°C, 2h), and then calcining it (in the first stage calcination process, the temperature is 600°C and the holding time is 4h; in the second stage calcination process, the temperature is 900°C and the holding time is 2h; in the third stage calcination process, the temperature is 1150°C and the holding time is 2h; in the fourth stage calcination process, the temperature is 1400°C and the holding time is 2h) to obtain a spinel structure high entropy oxide powder (its XRD pattern is as shown in FIG. Figure 1 Its reflectivity curve is shown as Figure 2 shown);

[0070] Zirconium acetate, tetrabutyl titanate, hafnium acetate, cerium acetate, and lanthanum acetylacetonate were dissolved in methanol in equal moles and blended to obtain a mixed solution having a metal ion concentration of 1.0 mol / L.

[0071] (S3) The spinel structure high entropy oxide powder prepared in step (S2) and the mixed solution prepared in step (S2) (the mass ratio of the spinel structure high entropy oxide powder to the mixed solution is 1:4) are mixed and placed in a Teflon autoclave for solvent thermal reaction (250°C, 48h) to achieve in situ synthesis of fluorite structure high entropy nano-oxide shell on the surface of the spinel high entropy oxide; the precipitate of the synthetic product is centrifuged to separate the liquid phase, washed twice with chloroform, and then washed with ether to perform a gelation process; the gel is dried at 80°C to obtain an atomic-level complex phase high entropy oxide coating material: spinel / fluorite structure complex phase ceramic oxide powder (its XRD pattern is as shown in FIG. Figure 3 Its reflectivity curve is shown as Figure 4 As shown in the figure, the spinel / fluorite structured composite high entropy oxide coating material was subjected to a thermal stability test at 1550℃ for 500h before and after. Figure 5 shown).

[0072] pass Figure 1 It can be found that the spinel structure high entropy oxide prepared in this embodiment is a single-phase spinel structure; Figure 3 It can be found that the reflectivity of the spinel structure high entropy oxide is 0.71 in the entire band, among which the emissivity reaches 0.85 in the 2.5-5μm band;

[0073] pass Figure 3 It can be found that the spinel / fluorite structure composite ceramic oxide powder prepared in this embodiment is mainly composed of fluorite structure, indicating that the spinel powder is completely covered by the fluorite structure shell; Figure 4 It can be found that the spinel / fluorite structured complex phase high entropy oxide has a high emissivity, which can reach above 0.91 in the 3-15μm band, and has comprehensive excellent infrared electromagnetic wave emission and reflection radiation performance.

[0074] pass Figure 5 It can be found that the spinel / fluorite structured multiphase high entropy oxide coating material prepared in this embodiment has excellent stability.

[0075] Example 2

[0076] This embodiment provides a method for preparing an atomic-level multiphase high-entropy oxide coating, as follows:

[0077] (A1) The spinel / fluorite structured composite ceramic oxide powder prepared in Example 1 was blended with a film-forming agent solution (5 wt % polyvinyl alcohol aqueous solution), and magnetically stirred for 30 minutes to ensure uniform dispersion to obtain a slurry. The slurry viscosity was controlled by adjusting the ceramic solid content concentration, wherein the mass fraction of the spinel / fluorite structured composite ceramic oxide powder was 75%. 1.5 wt % of commercial functional additives (fumed silica as an anti-settling agent, KH560 as a defoaming agent, and polyvinyl pyrrolidone as a dispersant) were added to adjust the coating uniformity, and the mixture was mixed to obtain a mixed slurry.

[0078] (A2) The surface of the quartz refractory brick substrate is polished with sandpaper to remove contaminants or an oxide layer, and then the surface is blown with a high-speed airflow for 5 minutes; then, a coating is applied to the treated substrate surface by spraying, with each coating thickness controlled to be 35 to 50 μm. The coating thickness is prepared by multiple spraying processes to a thickness of 300 μm.

[0079] (A3) drying the coated quartz refractory brick substrate at room temperature at 25° C. for 48 hours, and then subjecting the quartz refractory brick substrate to a stepwise calcination treatment to obtain a composite coating that is well bonded to the metal substrate and has a high density;

[0080] Among them, the step-by-step temperature calcination process is under a nitrogen atmosphere, including the first stage calcination treatment, the second stage calcination treatment, the third stage calcination treatment and the fourth stage calcination treatment in sequence. During the first stage calcination treatment, the temperature is 600°C and the holding time is 4h; during the second stage calcination treatment, the temperature is 900°C and the holding time is 2h; during the third stage calcination treatment, the temperature is 1150°C and the holding time is 2h; during the fourth stage calcination treatment, the temperature is 1600°C and the holding time is 6h; the full heating rate is 15°C / h; after the calcination, the furnace is cooled to obtain an atomic-level complex phase high entropy oxide coating tightly bonded to the quartz refractory brick matrix (its infrared emissivity is maintained above 0.94; a thermal stability experiment was carried out at 1550°C for 500h, and the optical microscope picture is as follows Figure 6 shown).

[0081] pass Figure 6 It can be found that the structure of the atomic-level multiphase high-entropy oxide coating prepared in this embodiment remains very stable after heat treatment.

[0082] Comparative Example 1

[0083] This comparative example provides a method for preparing an oxide coating material, which is as follows:

[0084] (S1) dispersing Mg2AlO4 and transition metal alloy powder (Cr powder, Fe powder, and Ni powder in equal molar ratios) in 100 parts of isopropanol and mixing them uniformly, wherein the mass fraction of Mg2AlO4 is 50 parts and the mass fraction of the transition metal alloy powder is 50 parts, and then preparing a spinel structure high entropy oxide precursor powder by planetary high energy ball milling;

[0085] The milling process was carried out under nitrogen atmosphere at a speed of 2500 rpm for 10 h.

[0086] (S2) dissolving zirconium acetate, tetrabutyl titanate, hafnium acetate, cerium acetate, and lanthanum acetylacetonate in equimolar amounts in methanol and blending the mixture to obtain a mixed solution, wherein the metal ion concentration of the solution is 1.0 mol / L;

[0087] (S3) The spinel structure high entropy oxide precursor powder prepared in step (S1) and the mixed solution prepared in step (S2) (the mass ratio of the spinel structure high entropy oxide precursor powder to the mixed solution is 1:4) are mixed and dried at 80°C to obtain an oxide coating material (the emissivity curve of which is shown in FIG. Figure 7 shown).

[0088] pass Figure 7 It can be found that the oxide coating material prepared in this comparative example has a -1 The highest band emissivity is only 22%, 500~4000cm -1 The average emissivity of the band is 18.2%.

[0089] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the explanations of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A method for preparing an atomic-level multiphase high-entropy oxide coating material, characterized in that: The following steps are involved: (S1) dissolving Mg2AlO4 and transition metal alloy powder, mixing them, and ball milling them to obtain a spinel structure high entropy oxide precursor powder; The transition metal is selected from two or more of Co, Cr, Fe, Ni or Ta; (S2) freeze-drying the spinel structure high entropy oxide precursor powder prepared in step (S1), and then sintering it to obtain a spinel structure high entropy oxide powder; dissolving the metal salts and blending them to obtain a mixed solution; The metal is selected from five or more of Zr, Ti, Hf, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu or Sc; (S3) The spinel structure high entropy oxide powder prepared in step (S2) is mixed with the mixed solution prepared in step (S2) to perform a solvent thermal reaction, thereby realizing the in situ synthesis of a fluorite structure high entropy nano-oxide shell layer on the surface of the spinel high entropy oxide; then, the liquid phase is separated by precipitation and centrifugation, and the liquid phase is gelled after washing, and dried to obtain an atomic-level complex phase high entropy oxide coating material: spinel / fluorite structure complex phase ceramic oxide powder.

2. The method for preparing an atomic-level multiphase high entropy oxide coating material according to claim 1, characterized in that: In step (S1), the molar ratio of Mg2AlO4 to transition metal alloy powder is 1:1 to 5:1; The ball milling process is carried out under an inert gas atmosphere, and the ball milling medium is a mixture of zirconia balls with diameters of 3-4 mm, 6-7 mm, and 9-10 mm; the ball-to-material ratio is 10-20:1, the ball milling speed is 2000-3000 revolutions per minute, and the ball milling time is 8-16 hours.

3. The method for preparing an atomic-level multiphase high entropy oxide coating material according to claim 1, characterized in that: In step (S2), during the freeze-drying process, the temperature is -80 to -20°C and the time is 2 to 8 hours; During the sintering process, the temperature is 1200-1500°C and the time is 2-10 hours; In the mixed solution, the molar ratio of each metal is the same.

4. The method for preparing an atomic-level multiphase high entropy oxide coating material according to claim 1, characterized in that: In step (S3), the mass ratio of the spinel structure high entropy oxide powder to the mixed solution is 1:9 to 4:6; During the solvent thermal reaction, the temperature is 220-280°C and the time is 24-72 hours.

5. An atomic-level multiphase high-entropy oxide coating material, characterized in that: It is prepared by the method according to any one of claims 1 to 4.

6. Use of the atomic-level multiphase high-entropy oxide coating material according to claim 5 in preparing an atomic-level multiphase high-entropy oxide coating.

7. A method for preparing an atomic-level multiphase high-entropy oxide coating, characterized in that: The following steps are involved: (A1) mixing the atomic-level multiphase high entropy oxide coating material according to claim 5 with a film-forming agent to obtain a mixed slurry; (A2) coating the mixed slurry prepared in step (A1) on the pretreated substrate surface, drying it, and performing a stepwise temperature-increasing calcination treatment to obtain an atomic-level multiphase high-entropy oxide coating.

8. The method for preparing an atomic-level multiphase high-entropy oxide coating according to claim 7, characterized in that: In step (A1), the film-forming agent is selected from one or two of polyvinyl alcohol, polyethylene glycol, glutinous rice starch and chitosan; In the mixed slurry, the mass percentage of the atomic-level multiphase high entropy oxide coating material is 60% to 75%; In step (A2), the coating is selected from one of spraying, rolling or brushing; During the drying process, the temperature is 20-40°C and the time is more than 24 hours; The step-by-step heating calcination process includes the first stage calcination process, the second stage calcination process, the third stage calcination process and the fourth stage calcination process. During the first stage of calcination, the temperature is 550-650°C and the holding time is 2-8 hours; During the second stage of calcination, the temperature is 850-950°C and the holding time is 2-6 hours; During the third stage of calcination, the temperature is 1100-1200°C and the holding time is 2-6 hours; During the fourth stage of calcination, the temperature is 1400-1600°C and the holding time is 2-12 hours.

9. An atomic-level multiphase high-entropy oxide coating, characterized in that: It is prepared by the method according to any one of claims 7 to 8.

10. Use of the atomic-level multiphase high entropy oxide coating according to claim 9 in the field of ultra-high temperature thermal insulation and energy saving.

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