Solid waste-based high-temperature heat storage composite material based on gradient interface engineering and nanowhisker reinforcement and preparation method thereof

Abstract

The embodiment of the application provides a solid waste-based high-temperature heat storage composite material based on gradient interface engineering and nanowire reinforcement and a preparation method thereof, which comprises a porous framework, a phase change core material and a gradient reinforcement layer; the porous framework is a composite of one or both of alumina microspheres and silica microspheres, and the inside of the porous framework is a network structure that penetrates each other; the phase change core material is coated on the surface of the porous framework; and the gradient reinforcement layer comprises a vertical array of boron nitride nanosheets on the outer layer and silicon carbide nanowires on the inner layer. The application aims to utilize coal gangue solid waste, solve the problems of high-temperature phonon scattering and interface separation through in-situ synthesis of SiC nanowires and BN gradient interface structure, break through the dispersion and high-temperature stability bottleneck of the traditional filler adding method, and thus realize the high performance and environmental protection and economy of the solid waste-based high-temperature heat storage material.

Description

Technical Field

[0001] This invention relates to the field of high-temperature thermal storage materials technology, specifically to a solid waste-based high-temperature thermal storage composite material and its preparation method based on gradient interface engineering and nanofiber reinforcement. Background Technology

[0002] With increasing emphasis on energy utilization and environmental protection, high-temperature thermal storage materials, as a key component of energy conversion and storage, play a vital role in improving their performance for energy conservation, emission reduction, and efficient energy utilization.

[0003] In existing technologies, such as the mullite insulating brick disclosed in patent CN119977542A, the matrix toughness is enhanced by mullite whiskers, and the mechanical properties and thermal insulation are optimized by using a gradient porous structure. However, it mainly focuses on improving thermal insulation performance and does not adequately consider the thermal storage density and thermal stability of high-temperature thermal storage materials. Another patent, CN118324435A, proposes a high-temperature cracking inhibitor to improve the high-temperature crack resistance of concrete, but its application is limited to the field of building materials and does not involve the preparation and performance optimization of high-temperature thermal storage materials.

[0004] Based on the above analysis, existing technologies have shortcomings in the preparation of high-temperature thermal storage materials, especially in utilizing solid waste resources and improving thermal storage density and thermal stability. Summary of the Invention

[0005] The present invention aims to at least solve one of the technical problems existing in the prior art, and provides a solid waste-based high-temperature thermal storage composite material and its preparation method based on gradient interface engineering and nanowhisker reinforcement.

[0006] In a first aspect, embodiments of the present invention provide a solid waste-based high-temperature thermal storage composite material based on gradient interface engineering and nanofiber reinforcement, comprising a porous framework, a phase change core material, and a gradient reinforcement layer. The porous framework is one or a composite of two of alumina microspheres and silica microspheres, and the interior of the porous framework is a network structure with interconnected structures. The phase change core material is coated on the surface of the porous framework. The gradient reinforcement layer comprises a vertical array of boron nitride nanosheets on the outer layer and silicon carbide nanofibers on the inner layer. The vertical array of boron nitride nanosheets is assembled into a vertically arranged array by electrophoresis. The silicon carbide nanofibers are prepared by in-situ method, and the length and diameter are 10μm-30μm and 50nm-100nm, respectively.

[0007] The preparation method of the solid waste-based high-temperature thermal storage composite material based on gradient interface engineering and nanofiber reinforcement is as follows: Step 1: Acid leaching and purification of coal gangue (extraction of SiO2 / AlO2), and mixing with carbon source and pressing into a compact; Step 2: In-situ reaction synthesis of SiC whiskers: Under argon protection at 1450°C, the catalyst is nickel-based titanium dioxide, and the raw materials are phenylacetylene black and dimethylformamide aqueous solution (mass ratio of 1:1), with the addition of excess SiO2 (molar ratio of 1:3) and AlO2 (molar ratio of 1:2); after reacting for 5 h, SiC whiskers with lengths of 10 μm-30 μm and diameters of 50 nm-100 nm are obtained; Step 3: Electrophoretic deposition of BN nanosheets to form a vertical array; Step 4: Vacuum impregnation with molten salt to fill the porous framework.

[0008] Furthermore, the coal gangue in step 1 is powdery solid waste mined from coal mines.

[0009] Furthermore, the carbon source in step 1 is graphite powder.

[0010] Furthermore, the catalyst in step 2 is nickel-based titanium dioxide powder.

[0011] Furthermore, the reaction temperature in step 2 is 1450°C and the holding time is 5 hours.

[0012] Furthermore, the preparation parameters for the BN nanosheets in step 3 are: voltage of 20V, charge of 0.005C / dm, and electrophoresis time of 20min.

[0013] Furthermore, the molten salt in step 4 is a mixture of sodium carbonate and lithium chloride in a 1:1 mol ratio.

[0014] Furthermore, the porous framework and porous particles in step 4 have a particle size of 300~500nm.

[0015] Compared with existing technologies, this invention provides a solid waste-based high-temperature thermal storage composite material and its preparation method based on gradient interface engineering and nanofiber reinforcement. It aims to utilize coal gangue solid waste to solve the problems of high-temperature phonon scattering and interface separation by synthesizing SiC nanofibers and BN gradient interface structures in situ. This breaks through the bottlenecks of dispersion and high-temperature stability of traditional filler addition methods, thereby achieving high performance and environmentally friendly and economical solid waste-based high-temperature thermal storage materials. Detailed Implementation

[0016] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to specific embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the described embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] Unless otherwise specifically stated, the technical or scientific terms used in the embodiments of this invention should be understood in their ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains. The terms "comprising" or "including," as used in the embodiments of this invention, do not limit the shapes, numbers, steps, actions, operations, components, elements, and / or groups thereof mentioned, nor do they exclude the appearance or addition of one or more other different shapes, numbers, steps, actions, operations, components, elements, and / or groups thereof, or the inclusion of these.

[0018] 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 invention. Techniques, methods, and apparatus known to those skilled in the art may not be discussed in detail, but where appropriate, the illustrated techniques, methods, and apparatus should be considered part of the specification. In all examples shown and discussed herein, any other specific example may have different values.

[0019] In the description of the embodiments of the present invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In the embodiments of the present invention, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in the embodiments of the present invention, as well as the features of different embodiments or examples.

[0020] Example 1: A solid waste-based high-temperature thermal storage composite material based on gradient interface engineering and nanowhisker reinforcement, comprising a matrix, a phase change core material, and a gradient reinforcement layer. The gradient reinforcement layer consists of a boron nitride (BN) nanosheet vertical array layer, a porous framework, a SiC nanowhisker transition layer, and a molten salt phase change core, from the outside to the inside. The porous framework is prepared by high-temperature dehydration of a mixture of sodium silicate dihydrate and sodium aluminate water glass, and then treated with hydrochloric acid to obtain a porous solid residue rich in silica and alumina. The SiC nanowhisker transition layer is composed of hexagonal Parker silicon-carbon nanowhiskers with a diameter of 50-100 nm and an aspect ratio of 30, prepared in situ. The boron nitride (BN) nanosheet vertical array is composed of boron nitride nanosheets with high specific surface area and vertical array arrangement obtained by electrophoresis, with an in-plane thermal conductivity greater than 200 W / m·K.

[0021] The preparation method of the above high temperature heat storage composite material is as follows: (1) Preparation of porous skeleton: using sodium silicate dihydrate and sodium aluminate mixed water glass as raw material, deionized water as solvent, ammonium chloride is added under stirring until completely dissolved to obtain a colorless and transparent solution.

[0022] The resulting mixture was poured into a porcelain boat and placed in a muffle furnace to be heated to 500°C. After holding at that temperature for 6 hours, it was allowed to cool naturally to room temperature.

[0023] The obtained product was soaked in 1.0 mol / L dilute hydrochloric acid for 12 h, filtered and the residue was washed and dried to obtain a porous framework; (2) In-situ synthesis of SiC nano whiskers: The porous framework obtained in step (1) was mixed and ground with an appropriate amount of amorphous carbon, and then placed in a vacuum tube furnace, heated to 1450°C and kept at a constant temperature for 5 hours.

[0024] After natural cooling, the sample was taken out and SiC nanocrystals were obtained by sieving with a standard sieve; (3) Preparation of gradient reinforcement layer: BN nanosheets were directly grown on the substrate by electrophoresis and then the template agent was removed by physical or chemical means; First, a boron fluoride solution with a concentration of 0.02M was prepared, and 0.25g of polyvinylpyrrolidone was added to it as a dispersant and ultrasonically dispersed evenly.

[0025] Then, take 10 mL of the suspension and add it to 50 mL of deionized water containing 0.05 M ammonia. Stir thoroughly with a magnetic stirrer and then ultrasonically disperse for 20 minutes.

[0026] The prepared suspension was dropped onto the surface of the SiC nanocrystals obtained in step (2) using a spin coater, and then placed in an electric field environment. The study showed that under a voltage of +900V / cm, the BN nanosheet array grew vertically on the surface of the SiC whiskers with a thickness of more than 2μm; (4) Preparation of high temperature heat storage composite material: water-soluble sodium salt and lithium carbonate were mixed in a molar ratio of 2:1 to prepare a Na / Li mixed salt solution.

[0027] The SiC nanocrystals-SiO / AlO framework prepared in step (3) is placed in a mixed salt solution and vacuum impregnated for 24 hours to allow it to fully absorb the mixed salt solution. After that, it is taken out and dried to obtain a high-temperature heat storage composite material.

[0028] It should be noted that this invention relates to the concept of a high-temperature thermal storage composite material, but does not limit the specific composition and process parameters.

[0029] 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 composite material based on gradient interface engineering and nanofiber reinforcement, characterized in that, Includes a porous framework, a phase change core material, and a gradient reinforcement layer; The porous framework is one or a combination of two of alumina microspheres and silica microspheres, and the interior of the porous framework is a network structure with interconnected structures. The phase change core material is coated on the surface of the porous skeleton; The gradient enhancement layer comprises a vertical array of boron nitride nanosheets on the outer layer and silicon carbide nanowhiskers on the inner layer.

2. The solid waste-based high-temperature thermal storage composite material based on gradient interface engineering and nanofiber reinforcement according to claim 1, characterized in that, The boron nitride nanosheet vertical array is assembled into a vertically arranged array by electrophoresis. The silicon carbide nanocrystals were prepared by in-situ method, with lengths of 10μm-30μm and diameters of 50nm-100nm.

3. A method for preparing a solid waste-based high-temperature thermal storage composite material based on gradient interface engineering and nanofiber reinforcement as described in claim 1 or 2, characterized in that, The method includes the following steps: Step 1: Acid leaching and purification of coal gangue to extract SiO / AlO, then mixing with carbon source and pressing into a compact; Step 2: In-situ reaction synthesis of SiC whiskers: Under argon protection at 1450°C, the catalyst was nickel-based titanium dioxide, and the raw materials were phenylacetylene black and dimethylformamide aqueous solution in a mass ratio of 1:

1. Excess SiO2 (molar ratio of 1:3) and AlO2 (molar ratio of 1:2) were added. After 5 hours of reaction, SiC whiskers with lengths of 10μm-30μm and diameters of 50nm-100nm were obtained. Step 3: Electrophoretic deposition of BN nanosheets to form a vertical array; Step 4: Vacuum impregnation with molten salt to fill the porous skeleton.

4. The preparation method of the solid waste-based high-temperature thermal storage composite material based on gradient interface engineering and nanofiber reinforcement according to claim 3, characterized in that, The coal gangue in step 1 is a powdery solid waste extracted from coal mines.

5. The preparation method of the solid waste-based high-temperature thermal storage composite material based on gradient interface engineering and nanofiber reinforcement according to claim 3, characterized in that, The carbon source in step 1 is graphite powder.

6. The preparation method of the solid waste-based high-temperature thermal storage composite material based on gradient interface engineering and nanofiber reinforcement according to claim 3, characterized in that, The catalyst in step 2 is nickel-based titanium dioxide powder.

7. The preparation method of the solid waste-based high-temperature thermal storage composite material based on gradient interface engineering and nanofiber reinforcement according to claim 3, characterized in that, The reaction temperature in step 2 is 1450°C and the holding time is 5 hours.

8. The preparation method of the solid waste-based high-temperature thermal storage composite material based on gradient interface engineering and nanofiber reinforcement according to claim 3, characterized in that, The parameters for preparing BN nanosheets in step 3 are: voltage 20V, charge 0.005C / dm, and electrophoresis time 20min.

9. The preparation method of the solid waste-based high-temperature thermal storage composite material based on gradient interface engineering and nanofiber reinforcement according to claim 3, characterized in that, The molten salt in step 4 is a mixture of sodium carbonate and lithium chloride in a 1:1 mol ratio.

10. The preparation method of the solid waste-based high-temperature thermal storage composite material based on gradient interface engineering and nanofiber reinforcement according to claim 3, characterized in that, The porous framework and porous particles in step 4 have a particle size of 300~500nm.