Method for improving the absorption-emission ratio performance of a photothermal ceramic material by reconfiguring the reaction surface

Abstract

The present application relates to a method for improving the light-to-heat conversion ceramic absorption-radiation ratio performance. The method uses the strong interaction force between hydrogen peroxide and transition metal oxide ceramic surface to react and reconstruct the surface of the ceramic. After the H2O2 reaction and reconstruction pretreatment, the ceramic surface grain is locally damaged and collapsed, forming an amorphous thin layer. After high temperature heat treatment, the amorphous layer recrystallizes to form a uniform and firm nanoparticle layer, thereby forming a high absorption surface layer on the surface. At the same time, due to the controllable degree and depth of surface reconstruction, the original low radiation characteristics of the ceramic are effectively preserved. The method has good universality and is not only suitable for lanthanide single perovskite oxides, doped alkaline earth metal perovskite oxides, other rare earth elements and double perovskite oxides, but also can be extended to spinel type oxides and other transition metal oxide ceramic systems. The present application effectively realizes the surface reconstruction of various ceramic systems, and the process is simple and controllable, providing a feasible method for optimizing the performance of light-to-heat conversion ceramic materials for CSP systems.

Description

Technical Field

[0001] This invention belongs to the field of concentrated solar power generation, specifically relating to a generalized treatment method for surface reconstruction through the reaction of hydrogen peroxide with ceramic surfaces to improve their absorption-radiative ratio performance. This method utilizes the interaction between hydrogen peroxide solution and the ceramic surface to construct a layer of nanostructured particles with a light-trapping effect on the substrate surface, thereby preparing a high-temperature resistant, spectrally selective absorbing ceramic material with an integrated structure. This process ensures excellent high-temperature air atmosphere stability while significantly improving its light absorption performance across the entire spectrum, providing a reliable material modification path for improving the photothermal conversion efficiency of high-temperature concentrated solar power systems. Background Technology

[0002] The efficient conversion and utilization of solar energy is one of the important ways to alleviate global challenges such as the current energy crisis and environmental pollution. Currently, solar energy conversion and utilization includes solar thermal utilization, solar photovoltaic power generation, and solar water splitting and evaporation. Among these, the photothermal-electric conversion of solar energy is a crucial area of ​​solar energy application, capable of continuously supplying solar energy for thermal storage and achieving all-weather power generation, with advantages of being clean, renewable, and highly efficient. High-temperature concentrated solar power (CSP) systems have developed rapidly due to their high energy conversion efficiency. For example, large-scale high-temperature molten salt tower CSP power plants have been built in Hami City, Xinjiang, and Dunhuang City, Gansu, China. Guided by the "dual-carbon" strategy, this technology strongly drives sustainable energy development and efficiently creates economic value. In high-temperature concentrated solar power systems, the power generation efficiency directly depends on the performance of the photothermal conversion materials in the collector. These materials must possess high absorptivity to ensure sufficient solar energy absorption while achieving low infrared emissivity to minimize heat radiation loss. Furthermore, since CSP systems operate in high-temperature environments for extended periods, the materials must also possess excellent high-temperature resistance and oxidation resistance.

[0003] Currently, high-temperature photothermal conversion materials that have been extensively studied both domestically and internationally are mainly divided into two categories: intrinsic absorption type and spectrally selective coating type. Both types of materials have significant technical bottlenecks. Intrinsic absorption type materials, such as those designed in patents CN103273695A and US20140060518A1, are high-absorption, high-temperature photothermal conversion materials, including SiC, ZrC, and some nitride ceramics. Although these materials possess high thermal stability and mechanical properties, their basic optical properties lack selective absorption capabilities, and their high emissivity in the infrared band leads to significant thermal radiation losses, thus limiting further improvements in photothermal conversion efficiency. Spectrally selective absorption coating materials, such as those designed in patents CN106167892B, CN102954611A, and CN109883073B, feature multilayer metal-ceramic photothermal conversion coatings. Their disadvantage is that long-term operation at temperatures above 700 °C is prone to interlayer atomic migration and diffusion, leading to unstable behaviors such as oxidation and delamination, thereby diminishing selective absorption performance. Studies have shown that transition metal oxide ceramics have become a key focus of photothermal conversion material research in recent years due to their excellent thermal stability, oxidation resistance, and superior spectral selective absorption performance. These ceramics exhibit good chemical stability at high temperatures, but their absorption capacity still has room for further improvement. Summary of the Invention

[0004] The purpose of this invention is to provide a method for improving the absorption-radiation ratio of photothermal ceramic materials through reactive surface reconstruction, specifically a generalized preparation method that utilizes the reactive surface reconstruction of H2O2 with the ceramic surface to enhance its absorption-radiation ratio. This method employs the synergistic effect of H2O2 and heat treatment to reconstruct the surface of a ceramic matrix possessing high-temperature resistance and air atmosphere stability. H2O2 induces the disruption of the ceramic surface lattice, forming an amorphous precursor layer. After heat treatment, a stable nano-high-absorption layer is generated, thereby improving its solar energy absorption rate. The method described in this invention is applicable to various ceramic systems, including single perovskite, double perovskite, and spinel. After surface reconstruction using this invention, the light absorption rate of the ceramics is significantly improved, while low-energy radiation performance is effectively maintained. A typical example is the single perovskite selective absorbing ceramic La... 0.5 Sr 0.5 CoO3 (LSC5) is a typical example. After surface reconstruction using this method, the solar absorptivity α of LSC5 ceramics increased from 0.65 to 0.90, while maintaining a low emissivity ε (0.18). In a Fresnel lens simulation experiment simulating concentrated solar thermal conversion (light intensity 10.37 W·cm²), the solar absorptivity was increased. -2This technology achieves an increased thermal equilibrium temperature for photothermal conversion (977 ℃), significantly higher than commercial SiC (751 ℃) and the original LSC5 (832 ℃) ceramics, and maintains stable optical performance for extended periods in air at 800 ℃. This is of great significance for promoting the development of high-temperature photothermal power generation technology towards higher efficiency and greater stability.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows: A method for improving the absorption-radiation ratio performance of photothermal conversion ceramic materials through reactive surface reconstruction, characterized by the following specific steps:

[0006] Step 1. Dilute the hydrogen peroxide solution in deionized water to prepare a hydrogen peroxide solution with a mass concentration of 10-30%;

[0007] Step 2. Using transition metal oxide ceramic powder, ceramic green bodies are prepared by tape casting, and then high-temperature sintering is performed to obtain transition metal oxide photothermal conversion ceramic sheets;

[0008] Step 3. Place the transition metal oxide photothermal conversion ceramic sheet obtained in Step 2 into a reaction vessel with a circulating condensation function, add the 10-30% hydrogen peroxide solution prepared in Step 1, and react at 25-35 ℃ for 30-240 min; during the reaction, place the vibration probe of the intermittent vibration degasser in the solution and at a distance of 0.5-1 cm from the upper surface of the ceramic sheet for intermittent vibration degassing.

[0009] Step 4. After the reaction is complete, rinse and dry the surface of the ceramic sheet with deionized water; then keep it in a muffle furnace at 800-900 ℃ for 8-10 h to obtain the ceramic sheet with reconstructed surface.

[0010] The preferred transition metal oxide ceramic powder in step 2 is: lanthanide mono-perovskite oxides LaCoO3, LaFeO3, and LaMnO3, or perovskite oxides doped with alkaline earth metals, such as La. 0.5 Sr 0.5 CoO3, La 0.5 Sr 0.5 FeO3, La 0.5 Sr 0.5 MnO3, other rare earth elements and double perovskite oxide Sm 0.5 Sr 0.5 CoO3, Gd 0.7 Nd 0.3 BaCo2O5 is one of the spinel-type oxides MnCo2O4, CuCr2O4, and NiFe2O4.

[0011] The preferred parameters for intermittent vibration degassing in step 3 are: vibration for 1-5 seconds, pause for 1-10 seconds, and cyclic vibration until the reaction is complete. Intermittent vibration degassing is used to avoid the influence of the annular eddies formed by continuous vibration degassing on the surface, which would produce uneven rings.

[0012] The preferred method for preparing ceramic green bodies in step 2 is as follows: ceramic powder, solvent, dispersant, binder, plasticizer and surfactant are mixed and ball milled to prepare a slurry; the mixed slurry is used for casting, dried and cut into round pieces and stacked layer by layer, pressed into sheets and demolded to obtain ceramic green bodies.

[0013] The preferred high-temperature sintering step 2 is as follows: the ceramic green body is placed in a high-temperature furnace, and the temperature is first increased from room temperature to 400-500 ℃ at 1-2 ℃ / min and held for 3-6 h; then the temperature is increased to the sintering temperature of 1100-1400 ℃ at 2-4 ℃ / min and held for 8-12 h. After the sample is cooled in the furnace, it is taken out to obtain the transition metal oxide photothermal conversion ceramic sheet.

[0014] Preferably, the solvent is a mixed solvent composed of xylene or methyl ethyl ketone with a mass concentration of 12-14%, isopropanol or propylene glycol with a mass concentration of 56-58%, and ethanol or methanol with a mass concentration of 28-32%; the dispersant is at least one of castor oil or herring oil; the binder is polyvinyl butyral (PVB) or polymethyl methacrylate (PMMA); the plasticizer is dibutyl phthalate (DBP) or dioctyl phthalate (DOP); and the surfactant is KH560 or KH570 silane coupling agent.

[0015] The preferred mass percentage of each component in the slurry is as follows: 61-64% transition metal oxide ceramic powder, 1-2% dispersant, 4-6% binder, 2-3% plasticizer, 1-2% surfactant, and 25-28% solvent.

[0016] The mechanism of this invention is as follows: The core mechanism of this process lies in using H2O2 solution to induce a reaction on the surface of a ceramic substrate, thereby causing the surface lattice to break down and forming an amorphous precursor layer. This precursor layer is then transformed into a high-absorption nanoparticle layer through high-temperature thermal crystallization. By controlling the process parameters, the light absorption rate is improved without sacrificing the inherent low-emissivity characteristics of the substrate, thus achieving the goal of improving the absorption-emissivity ratio. When H2O2 comes into contact with the transition metal oxide ceramic surface, electron transfer causes the O0 bonds in the H2O2 molecules to break. The resulting hydroxyl groups combine with the surface transition metal element M (M = Cr, Mn, Fe, Co, Ni, Cu), leading to the breakage of the MO bonds in the lattice. The M-OH groups are released from the lattice into the liquid phase and generate vacancies. Due to the lattice disruption, alkaline earth metal elements in the lattice dissolve, resulting in the formation of an amorphous layer with a thickness of less than 100 nm on the surface. After high-temperature thermal crystallization, this layer recrystallizes to form a uniform nanoparticle layer, constructing a surface with higher absorption. By controlling the reaction conditions (concentration, time, temperature), the reconstruction depth can be controlled within 200 nm, significantly improving absorption performance while maintaining the original infrared emission characteristics of the substrate. A schematic diagram is shown below. Figure 2 As shown.

[0017] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0018] 1. This invention develops a universal surface reconstruction process based on the reaction reconstruction of H2O2 with the ceramic surface to improve its absorption-radiation ratio. Utilizing the chemical reaction between H2O2 and the transition metal oxide ceramic surface, along with the synergistic effect of heat treatment, a significant enhancement of light absorption in the ultraviolet-visible-near-infrared band is achieved without altering the main structure of the ceramic matrix or its high-temperature resistance and oxidation resistance. This process has good versatility and can be applied to various transition metal oxide ceramic systems, including single perovskite, double perovskite, and spinel. By generating a high-absorption nanoparticle layer through surface reconstruction, it provides a universal technical solution for improving the spectral selectivity of various photothermal conversion substrates.

[0019] 2. Taking the typical selective absorption ceramic LSC5 as an example, this ceramic inherently possesses excellent low infrared emissivity, high temperature resistance, and air atmosphere stability. After H2O2 surface reconstruction, its absorptivity α significantly increased from the original 0.65 to 0.90, while maintaining a low emissivity (ε = 0.18). Under the simulation conditions of a concentrated solar power (CSP) system, the photothermal conversion equilibrium temperature of the reconstructed sample reached 977 ℃, significantly better than commercial SiC (751 ℃) and the original LSC5 (832 ℃) ceramics. Furthermore, the reconstructed ceramic underwent multiple cyclic heat treatments at 800 ℃ (the required temperature for concentrated solar power generation) for 9 h (average daily sunshine duration), and its spectral performance did not decline, demonstrating good thermal stability. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the reaction apparatus for reconstructing ceramic surfaces by impregnation with hydrogen peroxide according to the present invention.

[0021] Figure 2 This is a schematic diagram illustrating the principle of improving the absorption-radiation ratio of photothermal ceramic materials through reactive surface reconstruction according to the present invention.

[0022] Figure 3 These are scanning electron microscope (SEM) images of the LSC5 surface before and after reconstruction as described in Example 3.

[0023] Figure 4 The images show the selective absorption spectra of commercial SiC and LSC5 ceramic surfaces before and after reconstruction in Example 3 of this invention.

[0024] Figure 5 This is a diagram showing the photothermal conversion equilibrium temperature before and after surface reconstruction of commercial SiC and LSC5 ceramics in Example 3 of the present invention.

[0025] Figure 6 This is a comparison chart of the absorption rates of different samples prepared in Examples 3-13 of the present invention before and after surface reconstruction. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, various exemplary embodiments of this invention are now described in detail. The invention will be further described in detail below with reference to the embodiments and accompanying drawings. This detailed description should not be considered as a limitation of the invention, but rather as a more detailed description of certain aspects, characteristics, and embodiments of the invention. A schematic diagram of the reaction apparatus for hydrogen peroxide impregnation and reconstruction of ceramic surfaces according to this invention is shown below. Figure 1 As shown.

[0027] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0028] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0029] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0030] The hydrogen peroxide used in the following examples is a commercially available 30 wt% aqueous solution of hydrogen peroxide, and the other raw materials are commercially available raw materials with a purity of 99.99%.

[0031] Example 1: Effect of an initial 10 wt% H₂O₂ solution on La at 25 °C 0.5 Sr 0.5 Surface reconstruction of CoO3 (LSC5) ceramics

[0032] (1) Solution preparation: Use deionized water and hydrogen peroxide solution to prepare a hydrogen peroxide solution with a concentration of 10 wt%;

[0033] (2) Preparation of LSC5 ceramic green body by casting: Take 61 g of LSC5 ceramic powder, 28 g of solvent (composed of 12 wt% xylene, 56 wt% isopropanol and 32 wt% ethanol), 2 g of castor oil dispersant, 4 g of polyvinyl butyral binder, 3 g of dibutyl phthalate plasticizer and 2 g of KH560 silane coupling agent surfactant, mix them, ball mill them evenly and then cast them. After drying, cut them into round pieces, stack them layer by layer and put them into a mold to press them into LSC5 ceramic green body.

[0034] (3) Sintering: The ceramic was placed in a high-temperature furnace and heated from room temperature to 450 ℃ at 2 ℃ / min. The temperature was held for 3 h to remove the glue. Finally, the temperature was increased to the sintering temperature of 1230 ℃ at 4 ℃ / min and held for 10 h. The sample was taken out after cooling to below room temperature with the furnace. Finally, LSC5 ceramic sheets were prepared.

[0035] (4) Surface reconstruction of the reaction: The ceramic sheet was placed in a circulating condenser reaction beaker, and 10 wt% hydrogen peroxide solution was added. The reaction was carried out at 25 ℃ for 120 min. The temperature was controlled by a circulating condenser, and degassing was performed intermittently with a vibration frequency of 1 s and a stop frequency of 10 s. The vibration probe was placed 0.5 cm away from the upper surface of the ceramic sheet.

[0036] (5) Heat treatment: After the reaction is completed, the ceramic surface is repeatedly rinsed with deionized water and dried, and then placed in a muffle furnace to react at 800 °C for 9 h.

[0037] Tests showed that treating a ceramic surface with a 10 wt% hydrogen peroxide solution at 25 °C for 120 min resulted in a light absorptivity of 0.68 and an infrared emissivity of 0.17. This was demonstrated in a Fresnel lens-simulated concentrated solar thermal conversion experiment (light intensity 10.37 W·cm²). -2 It achieved an increase in the photothermal conversion thermal equilibrium temperature (846 ℃), which is higher than that of commercial SiC (751 ℃) and original LSC5 (832 ℃) ceramics.

[0038] Example 2: Surface reconstruction of LSC5 ceramics using an initial H2O2 solution with a concentration of 30 wt% at 30 °C.

[0039] (1) Solution preparation: Use deionized water and hydrogen peroxide solution to prepare a hydrogen peroxide solution with a concentration of 30 wt%;

[0040] (2) LSC5 ceramic green bodies were prepared using the tape casting method described in Example 1;

[0041] (3) LSC5 ceramic sheets were prepared using the sintering method described in Example 1;

[0042] (4) The surface of the LSC5 ceramic sheet was reconstructed using the method in Example 1. A 30 wt% hydrogen peroxide solution was used, and the reaction was carried out at 35 °C for 30 min. A circulating condenser was used to control the temperature, and intermittent degassing was performed with a vibration frequency of 5 s and a stop frequency of 1 s. The vibration probe was placed 1 cm away from the upper surface of the ceramic sheet.

[0043] (5) The ceramic after hydrogen peroxide surface reconstruction was heat-treated using the heat treatment process in Example 1.

[0044] Tests showed that a ceramic surface treated with an initial H₂O₂ solution at 30 °C for 30 min exhibited a light absorptivity of 0.74 and an infrared emissivity of 0.18. This was demonstrated in a Fresnel lens-simulated concentrated solar thermal conversion experiment (light intensity 10.37 W·cm⁻¹). -2 It achieved an increase in the photothermal conversion thermal equilibrium temperature (881 ℃), which is higher than that of commercial SiC (751 ℃) and original LSC5 (832 ℃) ceramics.

[0045] Example 3: Long-term surface reconstruction of LSC5 ceramics using an initial H2O2 solution with a concentration of 30 wt% at 25 °C.

[0046] (1) Solution preparation: Use deionized water and hydrogen peroxide solution to prepare a hydrogen peroxide solution with a concentration of 30 wt%;

[0047] (2) LSC5 ceramic green bodies were prepared using the tape casting method described in Example 1;

[0048] (3) LSC5 ceramic sheets were prepared using the sintering method described in Example 1;

[0049] (4) The surface of the LSC5 ceramic sheet was reconstructed using the method in Example 1. A 30 wt% hydrogen peroxide solution was used, and the reaction was carried out at 25 °C for 220 min. The temperature was controlled by a circulating condenser, and intermittent degassing was performed by vibrating for 5 s and stopping for 1 s. The vibration probe was placed 1 cm away from the upper surface of the ceramic sheet.

[0050] (5) The ceramic after hydrogen peroxide surface reconstruction was heat-treated using the heat treatment process in Example 1.

[0051] The SEM images of ceramic surfaces treated with 30 wt% H2O2 solution at 25 ℃ for 220 min followed by heat treatment are shown below. Figure 3 It can be seen that the surface morphology after treatment has been reconstructed and is completely different from the original surface morphology. By measuring and comparing the diffuse reflectance spectra of this sample, the original LSC5, and commercially available high-temperature photothermal conversion ceramic SiC, its spectral selective absorption performance is as follows: Figure 4 As shown in Table 1, the light absorption rate and infrared emissivity are as follows. It can be seen that the LSC5 ceramic prepared by the method described in this patent has a much lower emissivity than commercially available SiC ceramics. Furthermore, after heat treatment, the low emissivity characteristic is almost completely preserved, while a significant increase in absorption rate is achieved.

[0052] In this embodiment, the diffuse reflectance spectrum of the ceramic sample treated with a 30 wt% H2O2 solution at 25 °C for 220 min for reconstruction showed that the absorptivity of the LSC5 ceramic, which exhibits high selective absorption, increased from 0.65 to 0.90 after surface reconstruction, while the emissivity remained at 0.18. Fresnel lenses were used to simulate the concentrated solar energy photothermal conversion, such as... Figure 5 As shown, at 10.37 W·cm -2 The photothermal conversion equilibrium temperature (977 °C) of the reconstructed sample under light intensity is higher than that of commercial SiC (751 °C) and original LSC5 (832 °C) ceramics. This invention has an enhancing effect on the selective absorption ratio of photothermal conversion materials in the LSC5 system.

[0053]

[0054] Table 1

[0055] Example 4: Long-term surface reconstruction of LaCoO3 (LCO) ceramics using an initial H2O2 solution with a concentration of 30 wt% at 25 °C.

[0056] (1) Solution preparation: Use deionized water and hydrogen peroxide solution to prepare a hydrogen peroxide solution with a concentration of 30 wt%;

[0057] (2) LCO ceramic green bodies were prepared using the tape casting method described in Example 1;

[0058] (3) LCO ceramic sheets were prepared using the sintering method described in Example 1;

[0059] (4) The surface of the LCO ceramic sheet was reconstructed using the method in Example 1. A 30 wt% hydrogen peroxide solution was used, and the reaction was carried out at 25 °C for 60 min. The remaining reaction conditions were the same as the surface reconstruction parameters in Example 1.

[0060] (5) The ceramic after hydrogen peroxide surface reconstruction was heat-treated using the heat treatment process in Example 1.

[0061] By testing the light absorption rate of LCO ceramics after surface treatment with 30 wt% H₂O₂ solution at 25 °C for 60 min followed by heat treatment, the light absorption rate of LCO increased from 0.73 to 0.77. This invention enhances the light absorption of LCO photothermal conversion ceramics.

[0062] Example 5: Surface reconstruction of LaFeO3 (LFO) ceramics using an initial H2O2 solution with a concentration of 30 wt% at 25 °C.

[0063] (1) Solution preparation: Use deionized water and hydrogen peroxide solution to prepare a hydrogen peroxide solution with a concentration of 30 wt%;

[0064] (2) Preparation of LFO ceramic green body by casting: Take 64 g of LFO ceramic powder, 25 g of solvent (composed of 14 wt% methyl ethyl ketone, 58 wt% propylene glycol and 28 wt% methanol), 1 g of herring oil dispersant, 6 g of polymethyl methacrylate, 2 g of dibutyl phthalate plasticizer and 2 g of KH570 silane coupling agent surfactant, mix them, ball mill them evenly and then cast them. After drying, cut them into round pieces, stack them layer by layer and put them into a mold to press them into LFO ceramic green body.

[0065] (3) Sintering: The ceramic is placed in a high-temperature furnace. The temperature is first increased from room temperature to 400℃ at 1℃ / min and held for 6 hours to remove the glue. Finally, the temperature is increased to sintering temperature of 1300℃ at 2℃ / min and held for 12 hours. The sample is taken out after cooling to below room temperature with the furnace. Finally, LFO ceramic sheets are prepared.

[0066] (4) Surface reconstruction of the reaction: The ceramic sheet was placed in a circulating condenser reaction beaker, and 30 wt% hydrogen peroxide solution was added. The reaction was carried out at 25 ℃ for 240 min. The temperature was controlled by a circulating condenser, and intermittent degassing was performed by vibrating for 5 s and stopping for 10 s. The vibration probe was placed 0.5 cm away from the upper surface of the ceramic sheet.

[0067] (5) Heat treatment: After the reaction is completed, the ceramic surface is repeatedly rinsed with deionized water and dried, and then placed in a muffle furnace to react at 800 °C for 8 h.

[0068] The LFO ceramic prepared in Example 5 initially showed an absorbance of 0.81, which increased to 0.86 after surface reconstruction.

[0069] Example 6: Effect of an initial 30 wt% H2O2 solution on La at 25 °C 0.5 Sr 0.5 Surface reconstruction of FeO3 (LSF5) ceramics

[0070] (1) Solution preparation: Use deionized water and hydrogen peroxide solution to prepare a hydrogen peroxide solution with a concentration of 30 wt%;

[0071] (2) LSF5 ceramic green bodies were prepared using the tape casting method described in Example 5;

[0072] (3) LSF5 ceramic sheets were prepared using the sintering method described in Example 5;

[0073] (4) The surface reconstruction method in Example 5 was used to reconstruct the surface of the prepared LSF5 ceramic sheet. The experimental parameters for H2O2 solution treatment and heat treatment were the same as those in Example 5.

[0074] The LSF5 ceramic prepared in Example 5 initially showed an absorption rate of 0.78, which increased to 0.84 after surface reconstruction.

[0075] Example 7: Surface reconstruction of LaMnO3 (LMO) ceramics using an initial H2O2 solution with a concentration of 30 wt% at 25 °C.

[0076] (1) Solution preparation: Use deionized water and hydrogen peroxide solution to prepare a hydrogen peroxide solution with a concentration of 30 wt%;

[0077] (2) Preparation of LMO ceramic green body by casting: Take 64 g of LMO ceramic powder, 25 g of solvent (composed of 14 wt% methyl ethyl ketone, 58 wt% propylene glycol and 28 wt% methanol), 2 g of castor oil dispersant, 5 g of polymethyl methacrylate, 3 g of dibutyl phthalate plasticizer and 1 g of KH560 silane coupling agent surfactant, mix them, ball mill them evenly and then cast them. After drying, cut them into round pieces, stack them layer by layer and put them into a mold to press them into LMO ceramic green body.

[0078] (3) Sintering: The ceramic is placed in a high-temperature furnace and heated from room temperature to 400 ℃ at 1 ℃ / min. It is held for 3 h to remove the glue. Finally, the temperature is increased to sintering temperature of 1350 ℃ at 1 ℃ / min and held for 12 h. The sample is taken out after cooling to below room temperature with the furnace. Finally, LMO ceramic sheets are prepared.

[0079] (4) Reconstruction of the reaction surface: The ceramic sheet was placed in a circulating condenser reaction beaker, and 30 wt% hydrogen peroxide solution was added. The reaction was carried out at 25 ℃ for 240 min. The temperature was controlled by a circulating condenser, and degassing was performed intermittently by vibrating for 5 s and stopping for 5 s. The vibration probe was placed 1 cm away from the upper surface of the ceramic sheet.

[0080] (5) Heat treatment: After the reaction is completed, the ceramic surface is repeatedly rinsed with deionized water and dried, and then placed in a muffle furnace to react at 800 °C for 10 h.

[0081] The LMO ceramic prepared in Example 7 showed an initial absorbance of 0.79, which increased to 0.87 after surface reconstruction.

[0082] Example 8: Effect of an initial 30 wt% H2O2 solution on La at 25 °C 0.5 Sr 0.5Surface reconstruction of MnO3 (LSM5) ceramics

[0083] (1) Solution preparation: Use deionized water and hydrogen peroxide solution to prepare a hydrogen peroxide solution with a concentration of 30 wt%;

[0084] (2) LSM5 ceramic green bodies were prepared using the tape casting method described in Example 7;

[0085] (3) LSM5 ceramic sheets were prepared using the sintering method described in Example 7;

[0086] (4) The surface reconstruction method in Example 7 was used to reconstruct the surface of the prepared LSM5 ceramic sheet. The experimental parameters for H2O2 solution treatment and heat treatment were the same as those in Example 7.

[0087] The LSM5 ceramic prepared in Example 8 showed an initial absorbance of 0.82, which increased to 0.89 after surface reconstruction.

[0088] Example 9: Effect of an initial 30 wt% H2O2 solution on Sm at 25 °C 0.5 Sr 0.5 Surface reconstruction of CoO3 (SSC5) ceramics was performed to verify the adaptability of the present invention to different rare earth metals at different A sites.

[0089] (1) Solution preparation: Use deionized water and hydrogen peroxide solution to prepare a hydrogen peroxide solution with a concentration of 30 wt%;

[0090] (2) Preparation of SSC5 ceramic green body by casting: Take 64 g of SSC5 ceramic powder, 32 g of solvent (composed of 14 wt% xylene, 56 wt% isopropanol and 30 wt% ethanol), 1 g of herring oil dispersant, 4 g of polymethyl methacrylate binder, 2 g of dibutyl phthalate plasticizer and 1 g of KH570 silane coupling agent surfactant, mix them, ball mill them evenly and then cast them. After drying, cut them into round pieces, stack them layer by layer and put them into a mold to press them into SSC5 ceramic green body.

[0091] (3) Sintering: The ceramic was placed in a high-temperature furnace and heated from room temperature to 450 ℃ at 2 ℃ / min. The temperature was held for 5 h to remove the glue. Finally, the temperature was increased to the sintering temperature of 1230 ℃ at 2 ℃ / min and held for 12 h. The sample was taken out after cooling to below room temperature with the furnace. Finally, SSC5 ceramic sheets were prepared.

[0092] (4) Reconstruction of the reaction surface: The ceramic sheet was placed in a circulating condenser reaction beaker, and 30 wt% hydrogen peroxide solution was added. The reaction was carried out at 25 ℃ for 220 min. The temperature was controlled by a circulating condenser, and degassing was performed intermittently with a vibration frequency of 1 s vibration and 1 s stop. The vibration probe was placed 1 cm away from the upper surface of the ceramic sheet.

[0093] (5) Heat treatment: After the reaction is completed, the ceramic surface is repeatedly rinsed with deionized water and dried, and then placed in a muffle furnace to react at 900 °C for 8 h.

[0094] The initial absorption rate of the SSC5 ceramic prepared in Example 9 was 0.74, and the absorption rate reached 0.89 after surface reconstruction.

[0095] Example 10: Effect of an initial 30 wt% H2O2 solution on Gd at 25 °C 0.7 Nd 0.3 Surface reconstruction of BaCo2O5 (GNBC3) ceramic was conducted to explore the adaptability of this invention to surface reconstruction of double perovskite ceramic sheets with different rare earth and alkaline earth metals.

[0096] (1) Solution preparation: Use deionized water and hydrogen peroxide solution to prepare a hydrogen peroxide solution with a concentration of 30 wt%;

[0097] (2) Preparation of GNBC3 ceramic green body by casting: Take 64 g of GNBC3 ceramic powder, 32 g of solvent (composed of 14 wt% xylene, 56 wt% isopropanol and 30 wt% ethanol), 1 g of castor oil dispersant, 4 g of polyvinyl butyral binder, 2 g of dibutyl phthalate plasticizer and 1 g of KH560 silane coupling agent surfactant, mix them, ball mill them evenly and then cast them. After drying, cut them into round pieces, stack them layer by layer and put them into a mold to press them into GNBC3 ceramic green body.

[0098] (3) Sintering: The ceramic was placed in a high-temperature furnace and heated from room temperature to 450 ℃ at 2 ℃ / min. It was held for 5 h to remove the glue. Finally, the temperature was increased to sintering temperature of 1100 ℃ at 2 ℃ / min and held for 12 h. The sample was taken out after cooling to below room temperature with the furnace. Finally, GNBC3 ceramic sheets were prepared.

[0099] (4) Surface reconstruction of the reaction: The ceramic sheet was placed in a circulating condenser reaction beaker, and 30 wt% hydrogen peroxide solution was added. The reaction was carried out at 25 ℃ for 220 min. The temperature was controlled by a circulating condenser, and degassing was performed intermittently with a vibration frequency of 5 s and a stop frequency of 10 s. The vibration probe was placed 0.5 cm away from the upper surface of the ceramic sheet.

[0100] (5) Heat treatment: After the reaction is completed, the ceramic surface is repeatedly rinsed with deionized water and dried, and then placed in a muffle furnace to react at 800 °C for 9 h.

[0101] The initial absorption rate of the GNBC3 ceramic prepared in Example 10 was 0.65, and the absorption rate reached 0.84 after surface reconstruction.

[0102] Example 11: Surface reconstruction of MnCo2O4 (MCO) ceramics was performed using an H2O2 solution with an initial concentration of 30 wt% at 25 °C to explore the possibility of surface reconstruction of spinel oxide ceramic sheets with different transition metal elements according to the present invention.

[0103] (1) Solution preparation: Use deionized water and hydrogen peroxide solution to prepare a hydrogen peroxide solution with a concentration of 30 wt%;

[0104] (2) Preparation of MCO ceramic green body by casting: Take 62 g of MCO ceramic powder, 28 g of solvent (composed of 12 wt% xylene, 56 wt% isopropanol and 32 wt% ethanol), 2 g of castor oil dispersant, 4 g of polyvinyl butyral binder, 2 g of dibutyl phthalate plasticizer and 2 g of KH560 silane coupling agent surfactant, mix them, ball mill them evenly and then cast them. After drying, cut them into round pieces, stack them layer by layer and put them into a mold to press them into MCO ceramic green body.

[0105] (3) Sintering: The ceramic is placed in a high-temperature furnace and heated from room temperature to 450 ℃ at 2 ℃ / min. It is held for 4 h to remove the glue. Then, the temperature is increased to the sintering temperature of 1100 ℃ at 2 ℃ / min and held for 10 h. The sample is taken out after cooling to below room temperature with the furnace. Finally, MCO ceramic sheets are prepared.

[0106] (4) Surface reconstruction of the reaction: The ceramic sheet was placed in a circulating condenser reaction beaker, and 30 wt% hydrogen peroxide solution was added. The reaction was carried out at 25 ℃ for 220 min. The temperature was controlled by a circulating condenser, and degassing was performed intermittently with a vibration frequency of 5 s and a stop frequency of 10 s. The vibration probe was placed 0.5 cm away from the upper surface of the ceramic sheet.

[0107] (5) Heat treatment: After the reaction is completed, the ceramic surface is repeatedly rinsed with deionized water and dried, and then placed in a muffle furnace to react at 900 °C for 10 h.

[0108] The initial absorption rate of the MCO ceramic prepared in Example 11 was 0.81, and the absorption rate reached 0.85 after surface reconstruction.

[0109] Example 12: Surface reconstruction of CuCr2O4 (CCO) ceramics was performed using an H2O2 solution with an initial concentration of 30 wt% at 25 °C to explore the possibility of surface reconstruction of spinel oxide ceramic sheets with different transition metal elements according to the present invention.

[0110] (1) Solution preparation: Use deionized water and hydrogen peroxide solution to prepare a hydrogen peroxide solution with a concentration of 30 wt%;

[0111] (2) Preparation of CCO ceramic green body by casting: Take 62 g of CCO ceramic powder, 28 g of solvent (composed of 12 wt% xylene, 56 wt% isopropanol and 32 wt% ethanol), 2 g of castor oil dispersant, 4 g of polyvinyl butyral binder, 2 g of dibutyl phthalate plasticizer and 2 g of KH560 silane coupling agent surfactant, mix them, ball mill them evenly and then cast them. After drying, cut them into round pieces, stack them layer by layer and put them into a mold to press them into CCO ceramic green body.

[0112] (3) Sintering: The ceramic is placed in a high-temperature furnace and heated from room temperature to 450 ℃ at 2 ℃ / min. It is held for 4 h to remove the glue. Then, the temperature is increased to the sintering temperature of 1100 ℃ at 2 ℃ / min and held for 10 h. The sample is taken out after cooling to below room temperature with the furnace. Finally, CCO ceramic sheets are prepared.

[0113] (4) The surface reconstruction method in Example 11 was used to reconstruct the surface of the prepared CCO ceramic sheet. The experimental parameters for H2O2 solution treatment and heat treatment were the same as those in Example 11.

[0114] The initial absorption rate of the CCO ceramic prepared in Example 12 was 0.85, and the absorption rate reached 0.91 after surface reconstruction.

[0115] Example 13: Surface reconstruction of NiFe2O4 (NFO) ceramics was performed using an H2O2 solution with an initial concentration of 30 wt% at 25 °C to explore the possibility of surface reconstruction of spinel oxide ceramic sheets with different transition metal elements according to the present invention.

[0116] (1) Solution preparation: Use deionized water and hydrogen peroxide solution to prepare a hydrogen peroxide solution with a concentration of 30 wt%;

[0117] (2) Preparation of NFO ceramic green body by tape casting: Take 62 g of NFO ceramic powder, 28 g of solvent (composed of 12 wt% xylene, 56 wt% isopropanol and 32 wt% ethanol), 2 g of castor oil dispersant, 4 g of polyvinyl butyral binder, 2 g of dibutyl phthalate plasticizer and 2 g of KH560 silane coupling agent surfactant, mix them, ball mill them evenly and then tape them. After drying, cut them into round pieces, stack them layer by layer and put them into a mold to press them into NFO ceramic green body.

[0118] (3) Sintering: The ceramic is placed in a high-temperature furnace and heated from room temperature to 450 ℃ at 2 ℃ / min. It is held for 4 h to remove the glue, and then heated to the sintering temperature of 1250 ℃ at 2 ℃ / min and held for 10 h. The sample is taken out after cooling to below room temperature with the furnace. Finally, NFO ceramic sheets are prepared.

[0119] (4) The surface reconstruction method in Example 11 was used to reconstruct the surface of the prepared NFO ceramic sheet. The experimental parameters for H2O2 solution treatment and heat treatment were the same as those in Example 11.

[0120] The NFO ceramic prepared in Example 13 initially showed an absorbance of 0.74, which increased to 0.76 after surface reconstruction.

[0121] The light absorption rates of the ceramics LCO, LSC5, LFO, LSF5, LMO, LSM5, SSC5, GNBC3, MCO, CCO, and NFO described in the above embodiments are compared before and after the surface reconstruction treatment using this method. Figure 6 As shown, this method can be seen to improve the performance of lanthanide single perovskite transition metal oxides, alkaline earth metal-doped transition metal perovskite oxides, ceramics with different rare earth elements, as well as double perovskite transition metal oxides and spinel transition metal oxide ceramics to varying degrees. This fully demonstrates that this method has good versatility in optimizing the photothermal conversion performance of transition metal oxide photothermal conversion ceramics.

[0122] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for improving the absorption-radiation ratio of photothermal conversion ceramic materials through reactive surface reconstruction, characterized in that, The specific steps are as follows: Step 1. Dilute the hydrogen peroxide solution in deionized water to prepare a hydrogen peroxide solution with a mass concentration of 10-30%; Step 2. Using transition metal oxide ceramic powder, ceramic green bodies are prepared by tape casting, and then high-temperature sintering is performed to obtain transition metal oxide photothermal conversion ceramic sheets; Step 3. Place the transition metal oxide photothermal conversion ceramic sheet obtained in Step 2 into a reaction vessel with a circulating condensation function, add the 10-30% hydrogen peroxide solution prepared in Step 1, and react at 25-35 ℃ for 30-240 min; during the reaction, place the vibration probe of the intermittent vibration degasser in the solution and at a distance of 0.5-1 cm from the upper surface of the ceramic sheet for intermittent vibration degassing. Step 4. After the reaction is complete, rinse and dry the surface of the ceramic sheet with deionized water; then keep it in a muffle furnace at 800-900 ℃ for 8-10 h to obtain the ceramic sheet with reconstructed surface.

2. The method as described in claim 1, characterized in that, The transition metal oxide ceramic powder mentioned in step 2 is one of the following: lanthanide mono-perovskite oxide, perovskite oxide doped with alkaline earth metal, other rare earth elements, and double perovskite oxide or spinel oxide.

3. The method as described in claim 2, characterized in that, The transition metal oxide ceramic powder mentioned in step 2 is LaCoO3, LaFeO3, LaMnO3, La 0.5 Sr 0.5 CoO3, La 0.5 Sr 0.5 FeO3, La 0.5 Sr 0.5 MnO3, Sm 0.5 Sr 0.5 CoO3, Gd 0.7 Nd 0.3 One of BaCo2O5, MnCo2O4, CuCr2O4 or NiFe2O4.

4. The method as described in claim 1, characterized in that, The parameters for the intermittent vibration degassing in step 3 are: 1-5 seconds of vibration followed by a 1-10 second pause.

5. The method as described in claim 1, characterized in that, The ceramic green body prepared by casting in step 2 is as follows: ceramic powder, solvent, dispersant, binder, plasticizer and surfactant are mixed and a slurry is prepared by ball milling; the mixed slurry is used for casting, dried and cut into round pieces and stacked layer by layer, pressed into sheets and demolded to obtain the ceramic green body.

6. The method as described in claim 1, characterized in that, The high-temperature sintering in step 2 is as follows: the ceramic green body is placed in a high-temperature furnace, and the temperature is first increased from room temperature to 400-500 ℃ at a rate of 1-2 ℃ / min and held for 3-6 h; then the temperature is increased to the sintering temperature of 1100-1400 ℃ at a rate of 2-4 ℃ / min and held for 8-12 h. After the sample is cooled in the furnace, it is taken out to obtain the transition metal oxide photothermal conversion ceramic sheet.

7. The method as described in claim 5, characterized in that, The solvent is a mixed solvent composed of xylene or methyl ethyl ketone with a mass concentration of 12-14%, isopropanol or propylene glycol with a mass concentration of 56-58%, and ethanol or methanol with a mass concentration of 28-32%; the dispersant is at least one of castor oil or herring oil; the binder is polyvinyl butyral (PVB) or polymethyl methacrylate (PMMA); the plasticizer is dibutyl phthalate (DBP) or dioctyl phthalate (DOP); and the surfactant is KH560 or KH570 silane coupling agent.

8. The method as described in claim 5, characterized in that, The mass percentages of each component in the slurry are as follows: transition metal oxide ceramic powder 61-64%, dispersant 1-2%, binder 4-6%, plasticizer 2-3%, surfactant 1-2%, and solvent 25-28%.

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