Solid waste-based high-temperature heat storage body and preparation method thereof

Abstract

The application provides a solid waste-based high-temperature heat storage body and a preparation method, the heat storage body is composed of a heat storage core part of a Ca-Al-Si-O base, and sequentially comprises, from inside to outside, a core layer, a transition layer and a surface layer; the surface layer is a dense layer of MgFe2O4, and the porosity is 65-68%; the porosity of the transition layer is 72-75%; the core layer is a dendritic fractal pore structure, and the porosity is 80-82%; wherein, the branch angle of the dendritic fractal pore structure has a preset angle; under the action of an applied 0.5T static magnetic field, the dense layer of MgFe2O4 and the dendritic fractal pore structure of the core layer cooperatively control material transmission to realize magnetic control of mass transfer; wherein, the direction of the static magnetic field is perpendicular to the surface of the surface layer. One technical effect of the application is that, by comprehensively optimizing chemical activation, pore structure design and sintering process, the thermal performance and reliability of the heat storage body are significantly improved.

Description

Technical Field

[0001] This invention belongs to the technical field of solid waste resource utilization and energy storage medium materials, specifically relating to a solid waste-based high-temperature thermal energy storage body and its preparation method. Background Technology

[0002] In the field of solid waste-based high-temperature thermal energy storage technology, Chinese invention patent CN115626825A discloses an alumina / lanthanide perovskite ceramic composite light absorber and its preparation method. It mainly focuses on improving light absorption performance but fails to address multi-level chemical synergistic activation technology in solid waste-based thermal energy storage, particularly the selective dissolution of calcium impurities, phase stabilization of aluminum impurities, and silicon-enhanced three-level directional transformation to achieve breakthroughs in impurity control. Chinese invention patent CN114980482A discloses a self-heating substrate and its preparation method. While it involves a self-heating substrate, it mainly focuses on phase change heat dissipation and coolant circulation heat dissipation, lacking in-depth discussion of the non-uniform pore topology construction of solid waste-based high-temperature thermal energy storage, especially the dendritic gradient pore design and magnetically assisted gradient sintering process, to achieve breakthroughs in structural design and sintering technology.

[0003] Therefore, although the aforementioned existing technologies have achieved significant results in the preparation of light absorbers and self-heating substrates, they mainly focus on the photothermal conversion efficiency and heat dissipation performance of materials, while there are still shortcomings in the comprehensive optimization of chemical activation, non-uniform pore topology construction, and gradient sintering process of solid waste-based high-temperature heat storage bodies.

[0004] Therefore, there is an urgent need for a solid waste-based high-temperature thermal energy storage body and its preparation method to solve the above-mentioned technical problems. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art, and to provide a new technical solution for a solid waste-based high-temperature thermal energy storage body and its preparation method.

[0006] According to a first aspect of the present invention, a solid waste-based high-temperature thermal energy storage body is provided, wherein the thermal energy storage body is centered on a thermal energy storage core composed of a Ca-Al-Si-O matrix, and consists of, from the inside out, a core layer, a transition layer and a surface layer. The surface layer is a dense MgFe2O4 layer with a porosity of 65-68%. The porosity of the transition layer is 72-75%; The core layer has a tree-like fractal porous structure with a porosity of 80-82%; wherein the branch angles of the tree-like fractal porous structure have a preset angle; The thermal storage core incorporates Y2O3@ZrO2 core-shell nanoparticles, where the Y2O3 component reacts with Al2O3 in the matrix to generate a yttrium aluminum garnet phase. Simultaneously, TiC and SiC nano-reinforcing phases are formed in situ through the decomposition of Ti3SiC2, synergistically achieving impurity stabilization and mechanical strengthening. Under the action of an external static magnetic field of 0.5T, the dendritic fractal pore structure of the MgFe2O4 dense layer and the core layer synergistically regulates mass transport to achieve magneto-controlled mass transfer; wherein, the direction of the static magnetic field is perpendicular to the surface of the layer.

[0007] Optionally, the thickness of the surface layer is 0.8 mm, the thickness of the transition layer is 1.2 mm, and the thickness of the core layer is 2 mm.

[0008] Optionally, the preset angle is 45°±2°.

[0009] Optionally, the surface layer is a magnesium-iron spinel layer formed by sintering at 1420°C.

[0010] According to a second aspect of the present invention, a method for preparing a solid waste-based high-temperature thermal energy storage body is provided, for preparing the solid waste-based high-temperature thermal energy storage body as described in the first aspect, comprising the following steps: Step S1: Selective leaching of calcium impurities is achieved through a NaOH-KOH synergistic alkaline dissolution method: a mixed alkaline solution of sodium hydroxide and potassium hydroxide with a molar ratio of 7:3 is used, and the reaction is carried out at 85-95℃ and 200 rpm with stirring. The calcium oxide leaching rate exceeds 93%. Step S2, thermodynamic and structural stabilization of the aluminum impurity phase: Core-shell structured Y2O3@ZrO2 nanoparticles with a mass fraction of 1.5-2.5% are added. During sintering, the Y2O3 core reacts in situ with the Al2O3 in the matrix layer, generating a phase with a thermal expansion coefficient of 4.5 × 10⁻⁶. -6 ℃ -1 The yttrium aluminum garnet phase achieves thermal stress matching and grain boundary pinning; the ternary layered ceramic with a mass fraction of 2.5-3.5% is added simultaneously, which decomposes into 50-80 nm TiC and SiC nano-reinforcing phases during high-temperature sintering, thereby reducing the sintering activation energy of the system to 280 kJ / mol. Step S3, Non-uniform pore topology construction: A gradient porous matrix with a non-uniform pore topology is constructed using laser selective melting technology. The structure consists of three layers from the outside to the inside: a surface layer with a porosity of 65-68% to provide surface strength and selective mass transfer interface; a transition layer with a porosity of 72-75% to achieve a smooth transition in mechanical and mass transfer properties; and a core layer with a porosity of 80-82%, which internally constructs a tree-like pore network with fractal characteristics to optimize fluid transport efficiency. Step S4, magnetically assisted gradient sintering: Fe3O4 nanoparticles are oriented and arranged in a directional manner by gradient temperature control between the surface and core layers, combined with a 0.5T static magnetic field to achieve structural ordering; 0.6-1.0 wt% of citric acid-modified iron tetroxide-coated carbon nanotubes are added, and FeO liquid phase is generated by carbothermal reduction at 1300℃ to promote grain boundary diffusion.

[0011] Optionally, the total concentration of the mixed alkali solution is 8-12 wt%.

[0012] Optionally, the surface layer is kept at 1420℃ for 1.5 hours.

[0013] Optionally, the surface heating rate is 8°C / min.

[0014] Optionally, the core layer is kept at 1120℃ for 3.5 hours.

[0015] Optionally, the branching angle of the dendritic pore network with fractal characteristics is 45°±2°.

[0016] One technical advantage of this invention is that: In the embodiments of this application, the solid waste-based high-temperature thermal energy storage body and its preparation method adopt a Ca-Al-Si cement system. Through multi-level chemical synergistic activation, the rate of rapid evolution of components is reduced, effectively improving its stability. At the same time, the non-uniform pore topology is used to avoid the influence of traditional uniform nanopore channels on the homogeneity of the heat transfer process.

[0017] Moreover, a pore structure optimized for heat transfer and enhanced permeation coupling was achieved for the trapezoidal pore matrix, effectively balancing heat transfer rate and storage capacity.

[0018] In addition, the preparation method of this solid waste-based high-temperature thermal energy storage body is based on gradient sintering with a static magnetic field, which reduces the frequency and intensity of the "hot spot" effect in traditional gradient sintering, and improves the mobility and connectivity of the lattice at the micro and nano scales, thereby promoting uniform heat transfer. Attached Figure Description

[0019] Figure 1 This is a cross-sectional schematic diagram of a solid waste-based high-temperature thermal energy storage body according to an embodiment of the present invention.

[0020] In the diagram: 1. Surface layer; 2. Transition layer; 3. Core layer; 4. Thermal storage core; 5. Dendritic fractal pores; 6. Direction of static magnetic field. Detailed Implementation Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present application.

[0021] The embodiments of this application will now be described in detail. Examples of these embodiments are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0022] The terms "first" and "second" in the specification and claims of this application may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise stated, "multiple" means two or more. Furthermore, "and / or" in the specification and claims indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0023] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0024] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0025] According to a first aspect of the invention, see Figure 1 A solid waste-based high-temperature thermal energy storage body is provided. The thermal energy storage body is centered on a thermal energy storage core 4 composed of a Ca-Al-Si-O matrix, and consists of a core layer 3, a transition layer 2 and a surface layer 1 from the inside out. The surface layer 1 is a dense MgFe2O4 layer with a porosity of 65-68%. The porosity of the transition layer 2 is 72-75%; The core layer 3 is a tree-like fractal pore structure 5 with a porosity of 80-82%; wherein, the branch angle of the tree-like fractal pore structure 5 has a preset angle; The thermal storage core 4 introduces Y2O3@ZrO2 core-shell nanoparticles, whose Y2O3 component reacts with Al2O3 in the matrix to generate yttrium aluminum garnet phase; at the same time, TiC and SiC nano-reinforcing phases are formed in situ through the decomposition of Ti3SiC2, which synergistically achieves impurity stabilization and mechanical strengthening. Under the action of an external static magnetic field of 0.5T, the dendritic fractal pore structure of the MgFe2O4 dense layer and the core layer 3 synergistically regulates the mass transport to achieve magneto-controlled mass transfer; wherein, the direction of the static magnetic field 6 is perpendicular to the surface.

[0026] In this embodiment, the solid waste-based high-temperature thermal energy storage body adopts a Ca-Al-Si cement system. Through multi-level chemical synergistic activation, the rate of rapid component evolution is reduced, effectively improving its stability. At the same time, the non-uniform pore topology is used to avoid the influence of traditional uniform nanopore channels on the homogeneity of the heat transfer process.

[0027] Moreover, a pore structure optimized for heat transfer and enhanced permeation coupling was achieved for the trapezoidal pore matrix, effectively balancing heat transfer rate and storage capacity.

[0028] In addition, the preparation method of this solid waste-based high-temperature thermal energy storage body is based on gradient sintering with a static magnetic field, which reduces the frequency and intensity of the "hot spot" effect in traditional gradient sintering, and improves the mobility and connectivity of the lattice at the micro and nano scales, thereby promoting uniform heat transfer.

[0029] It should be noted that the solid waste-based high-temperature thermal energy storage body uses Ca-Al-Si system cement as the thermal energy storage medium, and optimizes the interfacial reactions that are prone to occur between its phases. The thermal energy storage and release performance of the material is improved through multi-level chemical synergistic activation and non-uniform pore topology construction. At the same time, in order to improve the homogeneity and stability of the heat storage and extraction process, a gradient sintering process based on static magnetic field is proposed.

[0030] Optionally, the thickness of the surface layer 1 is 0.8 mm, the thickness of the transition layer is 1.2 mm, and the thickness of the core layer is 2 mm. This achieves a high degree of matching between the thickness distribution and functional requirements. The heat storage function mainly occurs in the core layer, so its thickness is the largest (2.0 mm) to ensure high energy storage density; the surface layer only serves a protective function, and 0.8 mm is sufficient to achieve densification, avoiding excessive material consumption or increased mass transfer resistance.

[0031] Optionally, the preset angle is 45°±2°. This can significantly reduce turbulence and vortices caused by abrupt changes in fluid direction, reduce local pressure drop, and achieve low-resistance, high-throughput material transport.

[0032] Optionally, the surface layer 1 is a magnesium-iron spinel layer sintered at 1420℃. This allows for a smooth transition between the dense surface layer and the internal dendritic fractal pores, achieving a functional gradient design of "dense on the outside and sparse on the inside".

[0033] According to a second aspect of the present invention, a method for preparing a solid waste-based high-temperature thermal energy storage body is provided, which is used to prepare the solid waste-based high-temperature thermal energy storage body as described in the first aspect, and aims to improve the thermal performance and reliability of the thermal energy storage body by comprehensively optimizing chemical activation, pore structure design and sintering process.

[0034] Specifically, the preparation method of this solid waste-based high-temperature thermal energy storage body includes the following steps: Step S1: Selective leaching of calcium impurities is achieved through the NaOH-KOH synergistic alkaline dissolution method: a mixed alkaline solution of sodium hydroxide and potassium hydroxide with a molar ratio of 7:3 is used, and the reaction is carried out at 85-95℃ and 200 rpm with stirring. The calcium oxide leaching rate exceeds 93%.

[0035] Step S2, thermodynamic and structural stabilization of the aluminum impurity phase: Core-shell structured Y2O3@ZrO2 nanoparticles with a mass fraction of 1.5-2.5% are added. During sintering, the Y2O3 core reacts in situ with the Al2O3 in the matrix layer, generating a phase with a thermal expansion coefficient of 4.5 × 10⁻⁶. -6 ℃ -1 The yttrium aluminum garnet phase achieves thermal stress matching and grain boundary pinning; simultaneously, 2.5-3.5% by mass of Ti3SiC2 ternary layered ceramic is added, which decomposes into 50-80 nm TiC and SiC nano-reinforcing phases during high-temperature sintering, thereby reducing the sintering activation energy of the system to 280 kJ / mol.

[0036] Step S3, Non-uniform pore topology construction: A gradient porous matrix with a non-uniform pore topology is constructed using laser selective melting technology. The structure consists of three layers from the outside to the inside: a surface layer with a porosity of 65-68% to provide surface strength and selective mass transfer interface; a transition layer with a porosity of 72-75% to achieve a smooth transition in mechanical and mass transfer properties; and a core layer with a porosity of 80-82%, which has a fractal tree-like pore network inside to optimize fluid transport efficiency.

[0037] In the above steps, a pore gradient from dense to highly permeable is formed, and low-resistance material transport is achieved through fractal tree topology.

[0038] Step S4, magnetically assisted gradient sintering: Fe3O4 nanoparticles are oriented and arranged in a directional manner by gradient temperature control between the surface and core layers, combined with a 0.5T static magnetic field to achieve structural ordering; 0.6-1.0 wt% of citric acid-modified iron tetroxide-coated carbon nanotubes are added, and FeO liquid phase is generated by carbothermal reduction at 1300℃ to promote grain boundary diffusion.

[0039] In the above embodiments, impurities are transformed into functional phases through a three-stage directional transformation mechanism of "calcium dissolution – aluminum stabilization – silicon reinforcement," overcoming the bottleneck of traditional impurity removal and obtaining a composite structure with a highly dense surface layer and a high-performance matrix working synergistically. Furthermore, the preparation method of this solid waste-based high-temperature thermal energy storage body is based on gradient sintering with a static magnetic field, which reduces the frequency and intensity of the "hot spot" effect in traditional gradient sintering, enhances the mobility and connectivity of the lattice at the micro- and nano-scale, thereby promoting uniform heat transfer.

[0040] Optionally, the total concentration of the mixed alkali solution is 8-12 wt%. This enables rapid dissolution of CaO while avoiding alkali crystallization or excessive volatilization, thus balancing reaction efficiency, operational safety, and equipment lifespan.

[0041] Optionally, the surface layer is held at 1420℃ for 1.5 hours. This enables the full densification of magnesium-iron spinel (MgFe2O4), promotes grain growth and grain boundary bonding, enhances structural integrity, stabilizes the spinel phase structure, and inhibits phase decomposition.

[0042] Optionally, the surface heating rate is 8°C / min, which helps to effectively control thermal stress and prevent cracking and delamination.

[0043] Optionally, the core layer is kept at 1120℃ for 3.5 hours, which helps to achieve a balance between "low-temperature densification" and "porosity retention".

[0044] Optionally, the branching angle of the fractal dendritic pore network is 45°±2°. This can significantly reduce turbulence and vortices caused by abrupt changes in fluid direction, reduce local pressure drop, and enable low-resistance, high-flux material transport.

[0045] Example 1 This embodiment provides a solid waste-based high-temperature thermal storage body based on multi-level chemical synergistic activation and non-uniform pore topology. See [link to previous document]. Figure 1 It includes a core-shell structured micro-nano composite doped and modified Ca-Al-Si-O-Ca thermal storage core and an outer gradient porous shell.

[0046] Specifically, the thermal storage core uses industrial by-product calcium oxide as the main material, mixed with 7 molar ratio of industrial by-product alumina and 1 molar ratio of industrial by-product silicon dioxide to obtain a Ca-Al-Si-O-Ca system. After reacting with a NaOH+KOH (7:3) mixed alkaline solution at 90℃ and 200 rpm, it is calcined at 800℃ in air for 60 hours, and finally mechanically ground to obtain Ca-Al-Si-O-Ca powder. Boron nitride nanosheets and sodium carbonate-lithium carbonate eutectic salt are filled into the outer gradient porous shell, and 0.5% citric acid-modified iron(III) oxide coated carbon nanotubes are added. The mixture is then prepared by vacuum impregnation and calcination at 400℃ in air for 8 hours. Subsequently, the Ca-Al-Si-O-Ca powder is added to a mixture containing Y2O3, TiO2, SiO2, and Al2O3. In a mixed slurry of O3, highly dispersed core-shell structured composite doped modified Ca-Al-Si-O-Ca powder was obtained by high-speed ball milling for 4 hours, drying at 70℃, and stirring at 500 rpm, with 80 g / L polyvinyl alcohol (PVA) as a dispersant, 4 g / L polyacrylamide (PAM) as a stabilizer, and 2 g / L hexadecyltrimethylammonium bromide (CTAB) as a surfactant. Next, the obtained core-shell structured composite doped modified Ca-Al-Si-O-Ca powder was in-situ composited with zinc high-stearate (ZnSt) and simultaneously molded, and then annealed in a vacuum environment at 950℃ for 3 hours to form a primary green body. Finally, it was hot-pressed at -6 MPa for 15 minutes and sintered at 800℃ in one pass to form a solid waste-based high-temperature thermal energy storage body with dimensions of 40 mm × 20 mm × 10 mm.

[0047] In the above embodiments, the performance parameters of the solid waste-based high-temperature thermal energy storage product are as follows: it has stable thermal energy storage performance, with a thermal energy storage capacity of 44.3 kJ / kg in the range of 100℃ to 900℃, a heat release capacity of 67.7 kJ / kg from 900℃ to room temperature, a phase change temperature of 836±2.33K, a thermal conductivity of 0.69 W / mK, a volume expansion rate of 2.13×10 / K, and a high-temperature resistance strength of 30.2 MPa.

[0048] Therefore, the solid waste-based high-temperature thermal energy storage body prepared by the preparation method of the solid waste-based high-temperature thermal energy storage body provided in this application can significantly improve the thermal performance and reliability of the thermal energy storage body.

[0049] Example 2 This embodiment provides a solid waste-based high-temperature thermal energy storage body based on multi-level chemical synergistic activation and non-uniform pore topology, including a core-shell structure micro-nano composite doped modified Ca-Al-Si-O-Ca thermal energy storage core and an outer gradient pore shell.

[0050] Specifically, the thermal storage core uses industrial by-product calcium oxide as the main material, mixed with 3 molar ratio of industrial by-product alumina and 1 molar ratio of industrial by-product silica to obtain a Ca-Al-Si-O-Ca system. After reacting with a NaOH+KOH (7:3) mixed alkaline solution at 85℃ and 180 rpm, it is calcined at 700℃ in air for 50 hours, and finally mechanically ground to obtain Ca-Al-Si-O-Ca powder. Boron nitride nanosheets and sodium carbonate-lithium carbonate eutectic salt are filled into the outer gradient porous shell, and 0.3% citric acid-modified iron(III) oxide coated carbon nanotubes are added as an additive. The mixture is then prepared by vacuum impregnation and calcination at 350℃ in air for 6 hours. Subsequently, the Ca-Al-Si-O-Ca powder is added to a mixture containing YO, TiO, SiO, and AlO. In a mixed slurry, highly dispersed core-shell structured composite doped modified Ca-Al-Si-O-Ca powder was obtained by high-speed ball milling for 3 hours, drying at 50℃, and stirring at 600 rpm, with 80 g / L polyvinyl alcohol (PVA) as a dispersant, 4 g / L polyacrylamide (PAM) as a stabilizer, and 2 g / L hexadecyltrimethylammonium bromide (CTAB) as a surfactant. Then, the obtained core-shell structured composite doped modified Ca-Al-Si-O-Ca powder was in-situ composited with zinc high-stearate (ZnSt) and simultaneously molded, and annealed in a vacuum environment at 850℃ for 5 hours to form a primary green body. Finally, it was hot-pressed at -5 MPa for 10 minutes and sintered at 750℃ in one pass to form a solid waste-based high-temperature thermal energy storage body with dimensions of 40 mm × 20 mm × 10 mm.

[0051] In the above embodiments, the product performance parameters of the solid waste-based high-temperature thermal energy storage body are as follows: it has stable thermal energy storage performance, with a thermal energy storage capacity of 39.6 kJ / kg in the range of 100℃ to 900℃, a heat release capacity of 62.3 kJ / kg from 900℃ to room temperature, a phase change temperature of 845±2.22K, a thermal conductivity of 0.65 W / mK, a volume expansion rate of 2.01×10 / K, and a high-temperature resistance strength of 29.8 MPa.

[0052] Therefore, the solid waste-based high-temperature thermal energy storage body prepared by the preparation method of the solid waste-based high-temperature thermal energy storage body provided in this application significantly improves the thermal performance and reliability of the thermal energy storage body through comprehensive optimization of chemical activation, pore structure design and sintering process.

[0053] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A solid waste-based high-temperature thermal storage body, characterized in that, The thermal storage body is centered on a thermal storage core composed of a Ca-Al-Si-O matrix, and consists of, from the inside out, a core layer, a transition layer, and a surface layer. The surface layer is a dense MgFe2O4 layer with a porosity of 65-68%. The porosity of the transition layer is 72-75%; The core layer has a tree-like fractal porous structure with a porosity of 80-82%; wherein the branch angles of the tree-like fractal porous structure have a preset angle; The thermal storage core incorporates Y2O3@ZrO2 core-shell nanoparticles, where the Y2O3 component reacts with Al2O3 in the matrix to generate a yttrium aluminum garnet phase. Simultaneously, TiC and SiC nano-reinforcing phases are formed in situ through the decomposition of Ti3SiC2, synergistically achieving impurity stabilization and mechanical strengthening. Under the action of an external static magnetic field of 0.5T, the dendritic fractal pore structure of the MgFe2O4 dense layer and the core layer synergistically regulates mass transport to achieve magneto-controlled mass transfer; wherein, the direction of the static magnetic field is perpendicular to the surface of the layer.

2. The solid waste-based high-temperature thermal storage body according to claim 1, characterized in that, The thickness of the surface layer is 0.8 mm, the thickness of the transition layer is 1.2 mm, and the thickness of the core layer is 2 mm.

3. The solid waste-based high-temperature thermal storage body according to claim 1, characterized in that, The preset angle is 45°±2°.

4. The solid waste-based high-temperature thermal storage body according to claim 1, characterized in that, The surface layer is a magnesium-iron spinel layer formed by sintering at 1420℃.

5. A method for preparing a solid waste-based high-temperature thermal storage body, characterized in that, The method for preparing the solid waste-based high-temperature thermal storage body as described in any one of claims 1-4 comprises the following steps: Step S1: Selective leaching of calcium impurities is achieved through a NaOH-KOH synergistic alkaline dissolution method: a mixed alkaline solution of sodium hydroxide and potassium hydroxide with a molar ratio of 7:3 is used, and the reaction is carried out at 85-95℃ and 200 rpm with stirring. The calcium oxide leaching rate exceeds 93%. Step S2, thermodynamic and structural stabilization of the aluminum impurity phase: Core-shell structured Y2O3@ZrO2 nanoparticles with a mass fraction of 1.5-2.5% are added. During sintering, the Y2O3 core reacts in situ with the Al2O3 in the matrix layer, generating a phase with a thermal expansion coefficient of 4.5 × 10⁻⁶. -6 ℃ -1 The yttrium aluminum garnet phase achieves thermal stress matching and grain boundary pinning; the ternary layered ceramic with a mass fraction of 2.5-3.5% is added simultaneously, which decomposes into 50-80 nm TiC and SiC nano-reinforcing phases during high-temperature sintering, thereby reducing the sintering activation energy of the system to 280 kJ / mol. Step S3, Non-uniform pore topology construction: A gradient porous matrix with a non-uniform pore topology is constructed using laser selective melting technology. The structure consists of three layers from the outside to the inside: a surface layer with a porosity of 65-68% to provide surface strength and selective mass transfer interface; a transition layer with a porosity of 72-75% to achieve a smooth transition in mechanical and mass transfer properties; and a core layer with a porosity of 80-82%, which internally constructs a tree-like pore network with fractal characteristics to optimize fluid transport efficiency. Step S4, magnetically assisted gradient sintering: Fe3O4 nanoparticles are oriented and arranged in a directional manner by gradient temperature control between the surface and core layers, combined with a 0.5T static magnetic field to achieve structural ordering; 0.6-1.0 wt% of citric acid-modified iron tetroxide-coated carbon nanotubes are added, and FeO liquid phase is generated by carbothermal reduction at 1300℃ to promote grain boundary diffusion.

6. The method for preparing a solid waste-based high-temperature thermal energy storage body according to claim 5, characterized in that, The total concentration of the mixed alkaline solution is 8-12 wt%.

7. The method for preparing a solid waste-based high-temperature thermal energy storage body according to claim 5, characterized in that, The surface layer was kept at 1420℃ for 1.5 hours.

8. The method for preparing a solid waste-based high-temperature thermal energy storage body according to claim 7, characterized in that, The surface heating rate is 8℃ / min.

9. The method for preparing a solid waste-based high-temperature thermal energy storage body according to claim 5, characterized in that, The core layer is kept at 1120℃ for 3.5 hours.

10. The method for preparing a solid waste-based high-temperature thermal storage body according to claim 5, characterized in that, The branching angle of the dendritic pore network with fractal characteristics is 45°±2°.

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