CN113800945A - Loofah derived porous silicon carbide ceramic-based high-temperature photo-thermal storage material and preparation method thereof - Google Patents
Loofah derived porous silicon carbide ceramic-based high-temperature photo-thermal storage material and preparation method thereof Download PDFInfo
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Abstract
The invention discloses a loofah derived porous silicon carbide ceramic-based high-temperature photo-thermal storage material and a preparation method thereof, wherein the storage material is prepared by compounding a loofah derived porous silicon carbide framework and a phase-change material; the porosity of the loofah-derived porous silicon carbide framework is 60-90%, and the loofah-derived porous silicon carbide framework is prepared by carbonizing loofah filled with a carbon source, reacting with molten silicon and removing redundant silicon. The phase-change material is eutectic salt consisting of sodium chloride and sodium fluoride. And filling the phase change material in the pores of the porous silicon carbide ceramic skeleton by adopting a vacuum impregnation method to obtain the loofah derived porous silicon carbide ceramic-based high-temperature photo-thermal storage material. The towel gourd derived porous silicon carbide ceramic skeleton has excellent connectivity and adjustable porosity, the thermal conductivity of the storage material is obviously improved, the heat storage density is higher, the full-spectrum solar energy capturing capability is strong, and a new direction is provided for a substitute material of sustainable energy in the heat storage technology.
Description
Technical Field
The invention belongs to a phase-change heat storage material, and particularly relates to a composite heat storage material prepared by a porous silicon carbide ceramic skeleton derived from towel gourds and sodium chloride-sodium fluoride eutectic salt.
Background
Phase change materials are considered to be potential heat storage materials due to their large heat storage density and constant temperature during heat storage and release. However, the phase change material has low thermal conductivity, resulting in a slow heat storage rate. To solve this problem, a method of compounding a porous skeleton with a phase-change material is generally used to increase the thermal conductivity. The common porous frameworks comprise a porous metal framework, a porous carbon framework and the like, however, metal materials are easily corroded, especially in molten salt, and the metal density is high, so that the heat storage system is heavy and the heat storage density is low; while carbon materials are only suitable for low temperature thermal storage systems.
Ceramic materials, such as silicon carbide ceramics, have many excellent characteristics, such as high thermal conductivity, good high temperature oxidation resistance, good corrosion resistance, etc., and can avoid the use limitation of conventional metal frameworks or carbon frameworks. However, when the single porous silicon carbide ceramic is compounded with the phase change material, the porosity cannot be automatically adjusted due to the fixed size of the pores, and the heat conduction rate and the heat storage density of the heat storage material can be directly influenced. Therefore, the realization of adjustable pore structure to improve the heat storage performance of the composite material becomes a problem to be solved urgently.
Disclosure of Invention
The purpose of the invention is as follows: the first purpose of the invention is to provide a porous silicon carbide ceramic-based storage material with adjustable pore structure, high thermal conductivity and high energy storage density, derived from towel gourd; the second purpose of the invention is to provide a preparation method of the storage material.
The technical scheme is as follows: the invention relates to a loofah derived porous silicon carbide ceramic-based high-temperature photo-thermal storage material which is prepared by compounding a loofah derived porous silicon carbide framework and a phase-change material; wherein the porosity of the loofah-derived porous silicon carbide skeleton is 60-90%, and the mass ratio of the loofah-derived porous silicon carbide skeleton to the phase-change material is 45: 52 to 58.
Further, the loofah-derived porous silicon carbide skeleton is prepared by carbonizing loofah filled with a carbon source, reacting with molten silicon and removing redundant silicon.
Further, the carbon source comprises any one of flour, corn starch, cassava starch, sweet potato powder, bamboo powder, wood powder and straw powder.
Further, the phase-change material is eutectic salt consisting of sodium chloride and sodium fluoride; wherein the mass ratio of the sodium chloride to the sodium fluoride is 2-5: 5 to 8.
The invention also provides a preparation method of the loofah derived porous silicon carbide ceramic-based high-temperature photo-thermal storage material, which comprises the following steps:
(1) cleaning and drying the loofah sponge, dissolving a carbon source in deionized water to form slurry, removing the slurry and filling the slurry into the loofah sponge, and then carbonizing to obtain a porous precursor;
(2) taking the porous precursor and sufficient silicon particles to react in a high-temperature furnace to generate a silicon carbide-silicon compound, then placing the compound in a vacuum environment to evaporate, and removing excessive silicon to obtain a loofah derived porous silicon carbide skeleton;
(3) taking sodium fluoride and sodium chloride for ball milling, mixing uniformly, and then drying to obtain a phase-change material;
(4) and mixing the loofah derived porous silicon carbide framework with the phase-change material, and filling the phase-change material in the loofah derived porous silicon carbide framework by adopting a vacuum impregnation method to obtain the loofah derived porous silicon carbide ceramic-based high-temperature photo-thermal storage material.
Further, in the step (2), the evaporation temperature of the compound is 1750-1850 ℃, and the heat preservation time is 2-4 hours.
Further, in the step (2), the reaction temperature in the high-temperature furnace is 1500-1600 ℃, and the reaction time is 1-2 hours.
Further, in the step (1), the carbonization process comprises: firstly heating to 500 ℃ at a heating rate of 0.5 ℃/min under an inert gas atmosphere, then heating to 900-1100 ℃ at a heating rate of 1 ℃/min, and preserving heat for 30 min.
Further, in the step (3), the mixture of the sodium fluoride and the sodium chloride after ball milling is placed in a tube furnace to be dried for 24-48 h at 105 ℃ in an inert atmosphere, and then the temperature is raised to 350 ℃ to be dried for 24-48 h.
Further, in the step (4), the process parameters of the vacuum impregnation method are as follows: heating to 680-700 ℃ in a vacuum atmosphere, and preserving heat for 2-4 h.
Referring to the preparation process shown in fig. 1, retinervus Luffae fructus is of reticular fiber structure with naturally connected pores, and main chemical element composition is C6H10O5Therefore, the structure is beneficial to fully filling a carbon source in pores of the loofah sponge, the loofah sponge and the carbon source form a precursor containing C under the action of high-temperature carbonization, the structure of the original loofah sponge is reserved, and silicon carbide with a porous reticular fiber structure is formed after the reaction of the loofah sponge and molten silicon particles; subsequently, the phase change material can be successfully filled in the reserved communication pores by means of vacuum impregnation, so that the composite phase change material has high heat storage density and high thermal conductivity.
According to the invention, the adopted phase-change material is eutectic salt of sodium chloride and sodium fluoride, and the adopted blend salt containing the same cation composition can improve the phase-change enthalpy value of the eutectic salt relative to single chloride or fluoride, so as to change the heat storage performance of the composite storage material, wherein when the mass fraction of the sodium chloride and the sodium chloride is 30%: and when the content is 70%, the phase change enthalpy value of the prepared eutectic salt is highest. When the phase-change materials are blended, the phase-change materials need to be operated in a ball mill for 3-4 hours at a rotating speed of 300r/min, and the eutectic salt prepared under the condition is more fully mixed than other conditions.
The carbon source adopted by the invention is a mixture containing components such as starch, cellulose, hemicellulose, protein and the like, the substances form slurry and are filled in the structure of the loofah sponge, the synergistic effect of improving the strength of the skeleton structure and improving the heat storage performance can be simultaneously achieved, and the concrete preparation of the slurry is as follows: every 90 + -10 mL of deionized water was added with 100g of carbon source. On the one hand, the carbon source fills a large amount of pores, the overall physical strength of the loofah sponge is improved, the loofah sponge is guaranteed to be still capable of keeping a complete reticular fiber structure after carbonization, a crack-free porous carbon precursor can be obtained at a slow heating rate, and on the other hand, due to the high-temperature carbonization effect, components such as cellulose and hemicellulose in the carbon source are volatilized, so that the carbon source forms a porous structure after carbonization, and the heat storage density of the composite material is further improved due to the generation of the porous structure. Meanwhile, the addition amount of the carbon source can further adjust the porosity of the prepared towel gourd derived silicon carbide skeleton.
In the preparation process of the step (2), the excess generated Si is required to be removed, and in the removal process, the formed silicon carbide is required to be ensured not to be damaged, and the silicon in the silicon carbide is ensured not to be evaporated together. Therefore, in the actual evaporation process, the specific temperature needs to be strictly limited, too low temperature will cause that silicon can not be back-evaporated, and too high temperature will cause that the structure of silicon carbide is damaged; meanwhile, the heat preservation time needs to be further controlled in the evaporation process, and the silicon carbide ceramic prepared by adopting a multi-time heat preservation evaporation mode needs to be sampled and cooled regularly within the set heat preservation time, so that the compactness is optimal and the heat conductivity is highest.
In the step (1), the dried loofah sponge is required to be cut, the central part of the cylindrical loofah sponge is removed, and only the side surface of the cylindrical loofah sponge is reserved. The porous silicon carbide prepared by the method has more uniform pore structure.
Has the advantages that: compared with the prior art, the invention has the following remarkable advantages: (1) the porous silicon carbide ceramic skeleton derived from the towel gourd has excellent connectivity and adjustable porosity; (2) the thermal conductivity of the high-temperature photo-thermal storage material prepared by the invention is obviously improved, and the heat storage and release rate is higher; (3) the spectral absorption performance of the high-temperature photo-thermal storage material prepared by the invention is obviously improved, and the full-spectrum solar energy capturing capability is strong; (4) the high-temperature photo-thermal storage material prepared by the invention has higher heat storage density and simultaneously has high heat storage density and high power density; (5) the physical and chemical characteristics of each component of the composite phase-change heat storage material prepared by the invention have the characteristics of high strength and high phase-change enthalpy; (6) the porosity range of the prepared biological silicon carbide ceramic skeleton is 64-87%, and the limitation that the porosity of the traditional biological template derived ceramic is not adjustable is broken. The phase-change heat storage material prepared by the invention effectively improves the heat conductivity of the phase-change material, the heat conductivity of the composite material is as high as 20.7W/mK, the spectrum capture performance is obviously improved, the average spectrum absorption rate is improved from 18.5% to 95.3%, in addition, the heat storage density of the composite heat storage material is as high as 424J/g, and the melting point is 665.9 ℃.
Drawings
FIG. 1 is a schematic flow chart of the preparation of the storage material of the present invention;
FIG. 2 is an SEM photograph of a porous silicon carbide ceramic prepared in example 1;
FIG. 3 is the average spectral absorbance of the storage material prepared in example 1;
FIG. 4 shows the results of DSC enthalpy of phase change tests of eutectic salts of sodium chloride and sodium fluoride in different ratios;
FIG. 5 is a microscopic SEM topography of the porosity of the carbon template at 85%, 75%, 65%;
fig. 6 is a shape diagram of a precursor of the carbonized loofah sponge without flour in comparative example 1.
Detailed Description
The technical solution of the present invention will be further described in detail with reference to the accompanying drawings and examples.
Example 1
The first step is as follows: preparation of porous silicon carbide ceramic skeleton derived from towel gourd
Sequentially cleaning fructus Luffae with ethanol solution and deionized water, and drying in a drying oven. Cutting the dried loofah sponge, removing the central part of the cylindrical loofah and only keeping the side surface of the cylindrical loofah. 100g of weak flour was dissolved in 90mL of deionized water and mechanically stirred to homogeneity. Filling the low-gluten flour slurry into the pores of the silk melon twines, and drying at room temperature for 48 h. And then carbonizing the mixture in a tubular furnace, heating to 500 ℃ at a heating rate of 0.5 ℃/min under an inert gas atmosphere, then heating to 1000 ℃ at a heating rate of 1 ℃/min, and preserving heat for 30 min. The carbonized porous precursor is cut into a cylindrical sample with the diameter of 13 +/-0.3 mm by a circle taking machine, and then is cut into a disc-shaped sample with the thickness of 3 +/-0.3 mm by a diamond wire cutting machine. And (3) placing the cut porous carbon precursor into a high-temperature furnace, heating to 1550 ℃ in a vacuum atmosphere, and reacting with sufficient silicon particles for 1h to generate the SiC/Si compound. And finally, placing the SiC/Si compound generated by the reaction in a high-temperature furnace, heating to 1800 ℃ in a vacuum atmosphere, preserving the heat for 3 hours, taking out the sample every 1.5 hours, then placing the sample in the high-temperature furnace, and removing the redundant silicon by high-temperature evaporation to obtain the porous silicon carbide ceramic skeleton derived from the towel gourd, wherein the porosity is 70%.
The second step is that: preparation of phase change materials
According to the mass ratio of 3:7 weighing sodium fluoride and sodium chloride, placing the sodium fluoride and the sodium chloride in a ball mill, operating at the rotating speed of 300r/min for 4 hours, and fully and uniformly mixing; and then, fully drying in a tubular furnace to remove moisture, drying at 105 ℃ for 36h in an inert atmosphere, and then heating to 350 ℃ for drying for 36h to obtain the phase-change material for later use.
The third step: preparation of porous silicon carbide ceramic-based high-temperature photothermal storage material derived from towel gourd
Mixing the loofah derived porous silicon carbide ceramic skeleton obtained in the first step with the phase-change material obtained in the second step according to a mass ratio of 45: 55, placing the materials in a graphite crucible, heating the materials to 700 ℃ in a tube furnace in a vacuum atmosphere by adopting a vacuum impregnation method, and preserving heat for 3 hours to fill phase change materials in pores of the porous framework, thereby obtaining the porous silicon carbide ceramic-based high-temperature photo-thermal storage material derived from the towel gourd.
An SEM image of the porous silicon carbide ceramic prepared after the carbon precursor reacts with the molten silicon and the excess silicon is removed is shown in fig. 2. The morphology of the silicon carbide ceramic is consistent with that of the carbon precursor, and the SEM enlarged view of the biological silicon carbide ceramic shows that silicon carbide crystal grains are tightly arranged, which is attributed to the result of high-temperature sintering at 1800 ℃ and is beneficial to improving the thermal conductivity. In addition, no excess silicon not removed was found in the pores of the silicon carbide, and the silicon carbide sample had a high structural purity.
The performance parameters of the porous silicon carbide ceramic-based high-temperature photothermal storage material derived from towel gourd prepared in this example are as follows: the thermal conductivity of the material is measured by adopting a laser thermal conductivity meter, the spectral absorption rate of the material is measured by adopting a spectrophotometer, and the mass ratio of sodium chloride to sodium fluoride is 7: 3 latent heat of phase change. The thermal conductivity of the composite material is as high as 20.7W/mK, the spectrum capture performance is obviously improved, the heat storage density of the composite material is as high as 424kg/kJ, and the melting point is 665.9 ℃.
Referring to fig. 3, the average spectral absorption of the composite storage material is as high as 95.25%, and the average spectral absorption is calculated by the following formula:
wherein A (lambda) represents the spectral absorptivity of the sample in the range of 200-2000 nm, and S (lambda) represents the solar spectral absorptivity of the sample in the range of 200-2000 nm.
Example 2
The first step is as follows: preparation of porous silicon carbide ceramic skeleton derived from towel gourd
Sequentially cleaning fructus Luffae with ethanol solution and deionized water, and drying in a drying oven. Cutting the dried loofah sponge, removing the central part of the cylindrical loofah and only keeping the side surface of the cylindrical loofah. 100g of weak flour was dissolved in 80mL of deionized water and mechanically stirred to homogeneity. Filling the low-gluten flour slurry into the pores of the silk melon twines, and drying at room temperature for 48 h. And then carbonizing the mixture in a tubular furnace, heating to 500 ℃ at a heating rate of 0.5 ℃/min under an inert gas atmosphere, then heating to 900 ℃ at a heating rate of 1 ℃/min, and preserving heat for 30 min. The carbonized porous precursor is cut into a cylindrical sample with the diameter of 13 +/-0.3 mm by a circle taking machine, and then is cut into a disc-shaped sample with the thickness of 3 +/-0.3 mm by a diamond wire cutting machine. And (3) placing the cut porous carbon precursor in a high-temperature furnace, heating to 1500 ℃ in a vacuum atmosphere, and reacting with sufficient silicon particles for 1h to generate the SiC/Si compound. And finally, placing the SiC/Si compound generated by the reaction in a high-temperature furnace, heating to 1750 ℃ in a vacuum atmosphere, preserving the heat for 2 hours, taking out the sample every 1 hour, then placing the sample in the high-temperature furnace, and removing the redundant silicon by high-temperature evaporation to obtain the porous silicon carbide ceramic skeleton derived from the towel gourd, wherein the porosity is 70%.
The second step is that: preparation of phase change materials
According to the mass ratio of 3:7 weighing sodium fluoride and sodium chloride, placing the sodium fluoride and the sodium chloride in a ball mill, operating at the rotating speed of 300r/min for 3 hours, and fully and uniformly mixing; and then, fully drying in a tubular furnace to remove moisture, drying at 105 ℃ for 24h in an inert atmosphere, and then heating to 350 ℃ for drying for 24h to obtain the phase-change material for later use.
The third step: preparation of porous silicon carbide ceramic-based high-temperature photothermal storage material derived from towel gourd
Mixing the loofah derived porous silicon carbide ceramic skeleton obtained in the first step with the phase-change material obtained in the second step according to a mass ratio of 45: and 52, placing the materials into a graphite crucible, heating the materials to 680 ℃ in a tube furnace in a vacuum atmosphere by adopting a vacuum impregnation method, and preserving heat for 2 hours to fill the phase change materials in the pores of the porous framework, thereby obtaining the loofah derived porous silicon carbide ceramic-based high-temperature photo-thermal storage material.
Example 3
The first step is as follows: preparation of porous silicon carbide ceramic skeleton derived from towel gourd
Sequentially cleaning fructus Luffae with ethanol solution and deionized water, and drying in a drying oven. Cutting the dried loofah sponge, removing the central part of the cylindrical loofah and only keeping the side surface of the cylindrical loofah. 100g of corn starch was dissolved in 100mL of deionized water and stirred mechanically. Filling the corn starch slurry into the pores of the silk melon twines, and drying at room temperature for 48 h. And then carbonizing the mixture in a tubular furnace, heating to 500 ℃ at a heating rate of 0.5 ℃/min under an inert gas atmosphere, then heating to 1100 ℃ at a heating rate of 1 ℃/min, and preserving heat for 30 min. The carbonized porous precursor is cut into a cylindrical sample with the diameter of 13 +/-0.3 mm by a circle taking machine, and then is cut into a disc-shaped sample with the thickness of 3 +/-0.3 mm by a diamond wire cutting machine. And (3) placing the cut porous carbon precursor in a high-temperature furnace, heating to 1600 ℃ in a vacuum atmosphere, and reacting with sufficient silicon particles for 2h to generate the SiC/Si compound. And finally, placing the SiC/Si compound generated by the reaction in a high-temperature furnace, heating to 1850 ℃ in a vacuum atmosphere, preserving the heat for 4 hours, taking out the sample every 2 hours, then placing the sample in the high-temperature furnace, and removing the redundant silicon by high-temperature evaporation to obtain the porous silicon carbide ceramic skeleton derived from the towel gourd, wherein the porosity is 70%.
The second step is that: preparation of phase change materials
According to the mass ratio of 3:7 weighing sodium fluoride and sodium chloride, placing the sodium fluoride and the sodium chloride in a ball mill, operating at the rotating speed of 300r/min for 3 hours, and fully and uniformly mixing; and then, fully drying in a tubular furnace to remove moisture, drying for 48h at 105 ℃ in an inert atmosphere, and then heating to 350 ℃ for drying for 48h to obtain the phase-change material for later use.
The third step: preparation of porous silicon carbide ceramic-based high-temperature photothermal storage material derived from towel gourd
Mixing the loofah derived porous silicon carbide ceramic skeleton obtained in the first step with the phase-change material obtained in the second step according to a mass ratio of 45: 58 is placed in a graphite crucible, and is heated to 680 ℃ in a tube furnace in vacuum atmosphere by adopting a vacuum impregnation method, and is insulated for 2 hours, so that the phase-change material is filled in the pores of the porous framework, and the porous silicon carbide ceramic-based high-temperature photo-thermal storage material derived from the towel gourd is obtained.
Example 4
The specific preparation method is the same as that in example 1, except that the ratio of sodium fluoride to sodium chloride in the second step is different, and is 2: 8. 4:6 and 5: 5.
referring to FIG. 4, the results of the DSC enthalpy of transformation test of the eutectic salt of sodium chloride and sodium fluoride show that the enthalpy of transformation is 574.9kJ/kg, 555.2kJ/kg and 443.9kJ/kg when the mass ratio of NaF to NaCl is 2:8, 4:6 and 5:5, respectively. When the mass ratio of NaF to NaCl is 3:7, the phase transition enthalpy value is the highest and is 666.7 kJ/kg. Therefore, the proportion of the eutectic salt can greatly influence the phase change enthalpy value of the eutectic salt, and further influence the heat storage density of the composite phase change material, so that the selection of the eutectic salt with the optimal proportion has a crucial effect on the heat storage performance of the eutectic salt.
Example 5
The specific preparation method is the same as that of example 1, except that the addition amount of the carbon source is different.
The porosity and pore structure of the porous silicon carbide of the towel gourd play a crucial role in the heat storage/release performance of the porous silicon carbide of the towel gourd. Small pores are beneficial to increase thermal conductivity and thus heat transfer rate, but reduce heat storage density; large pore sizes favor phase change materials but slow the heat transfer rate. The porosity of the loofah derived silicon carbide can be regulated and controlled by regulating the amount of flour filled into the loofah. The porosity of the carbon precursor increased from 64% to 87% with increasing flour. The microscopic SEM topography of the carbon template with porosity of about 85%, 75% and 65% is shown in FIG. 5. Due to the diversity of the pore structures of the loofah sponge and the flour, the carbon template presents a hierarchical porous structure from millimeter to nanometer scale. The hierarchical porous structure can effectively increase the load rate of the phase change material and prevent the leakage of the phase change material, which is beneficial to the long-term and stable use of the heat storage system. Two pore morphologies were observed, derived from loofah and flour, respectively. The regular pore canal with smaller pore diameter is from the vegetable sponge, and the disordered network-shaped pore structure with larger pore diameter is from the flour. In addition, some millimeter-sized macropores are derived from the inherent macroscopic macropores of the loofah sponge.
Along with the change of the addition amount of the carbon source, the porosity of the prepared towel gourd derived porous silicon carbide ceramic skeleton is changed, and the porosity ranges from 60% to 90%. Therefore, by adjusting the addition amount of the carbon source, a series of loofah derived silicon carbide frameworks with different porosities can be obtained.
Comparative example 1
The loofah sponge is directly carbonized to react in a mode of not adding a carbon source, and the loofah sponge has very thin fiber, large pores and very low structural strength after carbonization. The obtained retinervus Luffae fructus without flour, and carbonized precursor are shown in figure 6. The silicon carbide sample prepared without adding flour is easy to damage the skeleton structure, fall on the ground and be broken, and the slag is easy to fall off.
Comparative example 2
The properties of the material prepared by adopting the traditional biomass carbon material such as charcoal instead of loofah sponge are compared as follows: the porosity of the silicon carbide is only 55%, the phase change enthalpy value of the pure phase change material (NaCl-KCl) is 470.3kJ/kg, and the heat storage density of the composite material is only 157 kJ/kg. Compared with the prior art, the loofah sponge has the characteristic that pores can be adjusted due to the special pore structure of the loofah sponge, the heat storage density is remarkably improved, and the material prepared by the embodiment can be widely applied to the heat storage technology as a substitute material of sustainable energy.
Claims (10)
1. A porous silicon carbide ceramic-based high-temperature photothermal storage material derived from towel gourd is characterized in that: the storage material is prepared by compounding a porous silicon carbide skeleton derived from towel gourd and a phase-change material; wherein the porosity of the loofah-derived porous silicon carbide skeleton is 60-90%, and the mass ratio of the loofah-derived porous silicon carbide skeleton to the phase-change material is 45: 52 to 58.
2. The loofah-derived porous silicon carbide ceramic-based high-temperature photothermal storage material according to claim 1, characterized in that: the loofah derived porous silicon carbide skeleton is prepared by carbonizing loofah filled with a carbon source, reacting with molten silicon and removing redundant silicon.
3. The loofah-derived porous silicon carbide ceramic-based high-temperature photothermal storage material according to claim 2, characterized in that: the carbon source comprises any one of flour, corn starch, cassava starch, sweet potato powder, bamboo powder, wood powder and straw powder.
4. The loofah-derived porous silicon carbide ceramic-based high-temperature photothermal storage material according to claim 1, characterized in that: the phase change material is eutectic salt consisting of sodium chloride and sodium fluoride; wherein the mass ratio of the sodium chloride to the sodium fluoride is 2-5: 5 to 8.
5. The method for preparing the loofah-derived porous silicon carbide ceramic-based high-temperature photothermal storage material according to any one of claims 1-4, comprising the steps of:
(1) cleaning and drying the loofah sponge, dissolving a carbon source in deionized water to form slurry, removing the slurry and filling the slurry into the loofah sponge, and then carbonizing to obtain a porous precursor;
(2) taking the porous precursor and sufficient silicon particles to react in a high-temperature furnace to generate a silicon carbide-silicon compound, then placing the compound in a vacuum environment to evaporate, and removing excessive silicon to obtain a loofah derived porous silicon carbide skeleton;
(3) taking sodium fluoride and sodium chloride for ball milling, mixing uniformly, and then drying to obtain a phase-change material;
(4) and mixing the loofah derived porous silicon carbide framework with the phase-change material, and filling the phase-change material in the loofah derived porous silicon carbide framework by adopting a vacuum impregnation method to obtain the loofah derived porous silicon carbide ceramic-based high-temperature photo-thermal storage material.
6. The preparation method of the loofah-derived porous silicon carbide ceramic-based high-temperature photothermal storage material according to claim 5, wherein the preparation method comprises the following steps: in the step (2), the evaporation temperature of the compound is 1750-1850 ℃, and the heat preservation time is 2-4 hours.
7. The preparation method of the loofah-derived porous silicon carbide ceramic-based high-temperature photothermal storage material according to claim 5, wherein the preparation method comprises the following steps: in the step (2), the reaction temperature in the high-temperature furnace is 1500-1600 ℃, and the reaction time is 1-2 h.
8. The preparation method of the loofah-derived porous silicon carbide ceramic-based high-temperature photothermal storage material according to claim 5, wherein the preparation method comprises the following steps: in the step (1), the carbonization process comprises: firstly heating to 500 ℃ at a heating rate of 0.5 ℃/min under an inert gas atmosphere, then heating to 900-1100 ℃ at a heating rate of 1 ℃/min, and preserving heat for 30 min.
9. The preparation method of the loofah-derived porous silicon carbide ceramic-based high-temperature photothermal storage material according to claim 5, wherein the preparation method comprises the following steps: in the step (3), the mixture of the sodium fluoride and the sodium chloride after ball milling is placed in a tube furnace to be dried for 24-48 h at 105 ℃ in an inert atmosphere, and then the temperature is raised to 350 ℃ to be dried for 24-48 h.
10. The preparation method of the loofah-derived porous silicon carbide ceramic-based high-temperature photothermal storage material according to claim 5, wherein the preparation method comprises the following steps: in the step (4), the process parameters of the vacuum impregnation method are as follows: heating to 680-700 ℃ in a vacuum atmosphere, and preserving heat for 2-4 h.
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