Preparation method and application of ceramic-based composite porous material

Abstract

The invention relates to a preparation method and application of a ceramic-based composite porous material, and belongs to the technical field of ceramic porous materials, the ceramic porous material is used as a skeleton, graphene oxide, PNaSS and PMPTC solutions are impregnated into the ceramic skeleton, and a ceramic / graphene / PNaSS and PMPTC composite multifunctional porous material is obtained through hydrothermal reaction, freeze drying, thermal reduction and other methods; the device can be applied to the evaporative cooling field or the seawater desalination field or the comprehensive energy utilization field; the porous material provided by the invention has the advantages of ultralight weight, high temperature resistance, corrosion resistance, high porosity, wide pore size distribution range (including nanoscale to millimeter scale cross-scale pores), adjustable pore structure characteristics and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of ceramic porous materials, and particularly relates to a preparation method and application of a ceramic-based composite porous material. Background Art

[0002] In the prior art, a seawater desalination system is integrated with a photovoltaic power generation system. High-energy photons in the solar radiation process are used for photovoltaic power generation, while the thermal energy generated by other low-energy photons is used for seawater desalination. Most importantly, not only fresh water is produced during the seawater desalination process, but the gas-liquid phase change process can also be used for cooling the photovoltaic panels. Therefore, the integrated design strategy of a photovoltaic power generation-evaporation cooling-seawater desalination multi-functional energy utilization system has become a key scientific issue. As the core component providing cooling capacity and fresh water vaporization, the material and pore structure of the evaporation carrier directly determine the efficiency of the entire energy utilization system. Although relevant design methods have been proposed, further research is still needed to develop a more efficient energy utilization system. Through a full study of the above problems, it is found that the evaporation carrier needs to meet the requirements of both cooling and salt discharge simultaneously.

[0003] A patent application document with the publication number CN 116354434A discloses a preparation method of a salt-tolerant polyelectrolyte porous material and its application in photothermal seawater desalination, including: (1) dissolving a polyelectrolyte in water to obtain a uniform solution, pouring it into a prefabricated mold for freezing; (2) demolding the frozen sample and soaking it in a low-temperature organic solvent to obtain a polyelectrolyte porous material; (3) rinsing the polyelectrolyte porous material with an organic solvent and then soaking it in an organic solvent containing a crosslinking agent to obtain a salt-tolerant polyelectrolyte porous material. By removing ice crystals by ice dissolution instead of ice sublimation, the operation process is simple, the energy consumption is low, and it does not involve any complex operation process, and the material preparation rate is greatly improved. However, the porous material obtained by the above method has poor mechanical properties, difficult operation and installation, and its pore structure is a random structure, and it is impossible to actively control the pore structure characteristics such as pore diameter, porosity, and pore morphology, so its effect and application range are limited. Summary of the Invention

[0004] In order to overcome the deficiencies of the above prior art, the purpose of the present invention is to provide a preparation method and application of a ceramic-based composite porous material. Using a ceramic porous material as the framework, graphene oxide, PNaSS, and PMPTC solutions are impregnated into the ceramic framework, and ceramic / graphene / PNaSS and PMPTC composite multi-functional porous materials are obtained through methods such as hydrothermal reaction, freeze-drying, and thermal reduction. The porous materials provided by the present invention have the advantages of ultra-light weight, high temperature resistance, corrosion resistance, high porosity, pore sizes ranging from nanometers to millimeters, a wide pore size distribution range, and adjustable pore structure characteristics.

[0005] In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0006] A preparation method of a ceramic-based composite porous material, comprising the following steps:

[0007] Step 1: Add graphene oxide powder, crosslinking agent, reducing agent, PNaSS and dilute PMPTC solution into deionized water, and stir and mix to obtain a premixed solution;

[0008] By mass ratio, graphene oxide powder: crosslinking agent: reducing agent: PNaSS: dilute PMPTC solution: deionized water = (0.3 - 5):(0.03 - 5):(1 - 12.5):(0 - 30):(0 - 30):100;

[0009] Step 2: Immerse the ceramic porous material into the premixed solution prepared in Step 1, place the ceramic porous material and the premixed solution in a vacuum barrel and evacuate to make the premixed solution fully impregnate into the pores of the ceramic porous material to obtain a product;

[0010] Step 3: Directionally freeze the product obtained in Step 2 to obtain a directional product;

[0011] The directional freezing specifically is:

[0012] The freezing temperature is -10°C to -196°C, and the freezing time is 0 - 10 h;

[0013] Step 4: Thaw the directional product obtained in Step 3 at room temperature, and then carry out a hydrothermal reaction. If the freezing in Step 3 is not carried out, carry out a hydrothermal reaction on the product obtained in Step 2. The hydrothermal reaction temperature is 60 - 160°C, and the reaction time is 0 - 12 h. If the hydrothermal reaction time is 0, skip the thawing and jump to Step 7;

[0014] Step 5: Repeat Steps 3 to 4 for 0 - 3 times; if the freezing time in Step 3 is 0, skip Step 5;

[0015] Step 6: Freeze the product obtained in Step 5 again. If Step 5 is skipped, freeze the product in Step 4. If the hydrothermal reaction time in Step 4 is 0, freeze the product obtained in Step 2 to obtain a frozen ceramic / graphene / PNaSS and PMPTC hydrogel;

[0016] Step 7: Freeze-dry the frozen ceramic / graphene / PNaSS and PMPTC hydrogel obtained in Step 6. If the hydrothermal reaction time in Step 4 is 0, freeze-dry the product in Step 3. The freeze-drying temperature is -30°C to -40°C, and the freeze-drying time is 12 - 240 h. After the ice crystals sublime, an anisotropic pore structure is left, and a ceramic / graphene / PNaSS and PMPTC composite porous material is obtained.

[0017] In step 2, the ceramic porous material is one or more of silicon carbide, aluminum nitride, silicon nitride, aluminum oxide, zirconium oxide, titanium dioxide, phosphate, rare earth oxide, fly ash, coal gangue, kaolin, montmorillonite, and spinel in any proportion.

[0018] The crosslinking agent in step 1 is one or more of sodium tetraborate, polyvinyl alcohol, stearic acid, cysteine, glutaraldehyde, and DNA molecular chain in any proportion; the reducing agent is one or more of ethylenediamine, sodium ascorbate, ammonium sulfide, ammonia water, diethylenetriamine, sodium bisulfite, sodium sulfide, thiourea, hydroiodic acid, and hydrazine hydrate in any proportion.

[0019] In step 2, the vacuum pumping time is 0.5 - 12 h.

[0020] In step 6, the freezing temperature is -10°C to -196°C, and the freezing time is 0.1 - 10 h.

[0021] A ceramic-based composite porous material is obtained by the above preparation method.

[0022] The ceramic-based composite porous material obtained by the above preparation method can be applied to the fields of evaporative cooling, seawater desalination, or integrated energy utilization.

[0023] Compared with the prior art, the advantages of the present invention are as follows:

[0024] (1) On the one hand, the porous material provided by the present invention enables fluid to be transported along a specified path by establishing the pores in the ceramic skeleton and the pores generated after the directional freeze-drying of ceramic / graphene / PNaSS and PMPTC hydrogels, that is, the present invention utilizes customized large-scale pores to transport more coolant to the position with a higher heat flux density, greatly improving the cooling efficiency and the critical heat flux density; on the other hand, through the self-assembly process of graphene sheets, PNaSS, and PMPTC, after the mixture of graphene oxide powder, crosslinking agent, reducing agent, PNaSS and PMPTC dilute solution, and deionized water, the self-assembly behavior occurs during the freezing and heating processes without additional manual operation, which is a spontaneous behavior; the capillary force of the small-scale pores formed by it is used to drive the fluid flow without additional power; the porous material provided by the present invention simultaneously includes millimeter-scale, micron-scale, and nanoscale pore structures, having strong capillary force and good permeability, and overcoming the disadvantage that the capillary force and permeability of a porous material with a uniform pore size cannot be both obtained.

[0025] (2) The porous material provided by the present invention includes cross-scale pore structures at the nano, micro, and millimeter levels, having natural advantages in desalination. Its small pores have abundant capillary forces to provide sufficient water supply, while the large pores provide a place for the convection of salts; the stable chemical properties of graphene aerogel and ceramic materials have excellent corrosion resistance, further enhancing the stability of the seawater desalination and utilization system. In addition, PNaSS and PMPTC materials have a selective adsorption effect on salt ions, slowing down the increase in the concentration of salt molecules and avoiding salt crystallization, further enhancing the desalination performance of the entire seawater desalination system.

[0026] (3) Using the porous material provided by the present invention as an evaporation carrier can simultaneously meet the cooling and desalination requirements. In addition, the poly(sodium 4-styrenesulfonate) (PNaSS) and poly(3-methyl-2-methylenepropanamido)propyltrimethylammonium chloride (PMPTC) materials with opposite charges have a selective adsorption effect on salt ions, slowing down the increase in the concentration of salt molecules, and thus avoiding salt crystallization. The PNaSS chain itself carries a negative charge and is more likely to attract sodium ions Na + , a large number of sodium ions Na + are adsorbed in the channels of the porous material, causing the charge sign on the channel surface to be reversed, that is, showing a positive charge. At this time, negatively charged counterions will be attracted into the channel, and the continuous passage of a large number of counterions can generate a streaming potential. The salt ions selectively pass through the charged channels, further slowing down the increase in the concentration of salt molecules, and thus avoiding salt crystallization, further enhancing the anti-salt crystallization performance of the entire seawater desalination system; the electricity generated in this part further improves the utilization efficiency of solar energy, and is expected to increase the comprehensive utilization efficiency of solar energy from about 72% reported in the current literature to 75% or even higher.

[0027] (4) The main components of the porous material provided by the present invention are ceramics and graphene. Both have high-temperature resistance characteristics, and at the same time, there is a lightweight ceramic skeleton with an ultra-high porosity and a certain mechanical strength, solving the disadvantages of easy ablation and large mass increment of metal porous materials in the thermal management system of aerospace equipment.

[0028] (5) The present invention designs the pore structure of the ceramic skeleton through mathematical methods, that is, the pore structure type, local changes in pores and pore diameters, or gradient changes along a certain direction, combines additive manufacturing technology to realize the customization of the ceramic skeleton, and at the same time uses the directional freeze-drying method, that is, the directional growth of the pore structure of graphene aerogel, to obtain ceramic / graphene / PNaSS and PMPTC porous materials with specific pore structure parameters to meet the needs of different application scenarios. For detailed applications, see the examples.

[0029] (6) The graphite aerogel material mainly composed of graphene has excellent thermal conductivity, and after being compounded with ceramics, PNaSS, and PMPTC materials, it improves the thermal conductivity of the entire composite material.

[0030] (7) The present invention provides porous materials with a wide range of applications, which can be used in fields such as aerospace evaporative cooling, electronic component evaporative cooling, seawater desalination, energy storage, and combined heat, electricity, and water production.

[0031] In summary, the present invention provides a multifunctional cross-scale porous composite material. Through the composite structure of a ceramic skeleton and graphene / polymer hydrogel, the synergistic effect of multi-level pores is realized. The pore structure is customized by mathematical modeling and additive manufacturing, and the pore structure is precisely regulated by combining the directional freeze-drying technology. The prepared material contains millimeter-scale, micron-scale, and nanoscale pores, effectively solving the problem that it is impossible to have both permeability and capillary force in traditional homogeneous materials. At the same time, it has the advantages of high temperature resistance, light weight and high strength, excellent thermal conductivity, and corrosion resistance, and can be widely used in fields such as thermal management, seawater desalination, and combined heat, electricity, and water production. Brief Description of the Drawings

[0032] Figure 1 Schematic diagram of the composite porous material prepared according to the present invention.

[0033] Figure 2 Schematic diagram of the "heat-electricity-water" co-production system in Example 1.

[0034] Figure 3 Schematic diagram of the seawater desalination and concentration difference power generation system in Example 2.

[0035] Figure 4 Schematic diagram of the evaporative cooling system in Example 3.

[0036] Figure 5 Pore size distribution diagram of the porous material proposed in Example 1.

[0037] Figure 6 Electron microscope image of the pores of the porous material proposed by the present invention.

[0038] Among them, 1: ceramic skeleton; 2: graphene oxide; 3: PNaSS and PMPTC; 4: ceramic / graphene / PNaSS and PMPTC composite porous material; 5: solar photovoltaic panel; 6: first condensation cover; 7: water outlet pipe; 8: first fresh water collector; 9: first bottom plate; 10: first seawater; 11: sunlight; 12: water vapor; 13: third ceramic / graphene / PNaSS and PMPTC composite porous material; 14: second seawater; 15: electrode; 16: fresh water; 17: second condensation cover; 18: water outlet; 19: second fresh water collector; 20: ceramic / graphene composite porous material; 21: reinforcing rib; 22: fairing; 23: second bottom plate; 24: pipeline; 25: flowing working medium inlet; 26: heat load; 27: second ceramic / graphene / PNaSS and PMPTC composite porous material. Detailed Description of the Invention

[0039] The present invention will be further described below in conjunction with embodiments.

[0040] The present invention provides a preparation method of a multifunctional porous material with characteristics such as ultra-light weight, high temperature resistance, corrosion resistance, high porosity, wide pore size distribution range, adjustable pore structure characteristics, and wide application range. Ceramic materials have the characteristics of light weight, high temperature resistance, and corrosion resistance. This method uses a ceramic porous material as a framework, impregnates solutions of graphene oxide 2, PNaSS, and PMPTC 3 into the ceramic framework 1, and obtains a ceramic / graphene / PNaSS and PMPTC composite porous material 4 through methods such as hydrothermal reaction, freeze-drying, and thermal reduction. The functions of the ceramic, graphene, PNaSS, and PMPTC materials are elaborated in detail as follows: (1) The ceramic framework 1 enhances the mechanical properties of the entire material, overcomes the shortcomings of poor mechanical properties of graphene aerogels, PNaSS, and PMPTC porous materials, and by designing the pore structure of the ceramic porous material, customization of the composite porous material with gradient changes in pore structure, porosity, and pore size in a certain direction can be achieved, while it is difficult to achieve pore structure customization for single graphene aerogels, PNaSS, and PMPTC porous materials; (2) Graphene aerogels have extremely high porosity. Through the directional freezing process, the directional growth of the pore structure can be achieved, providing a place for the transport of fluids to provide sufficient working fluids, and at the same time providing channels for the convection of salt ions, slowing down the crystallization of salts. The pores formed between the graphene sheets enhance the capillary force of the entire porous material. In addition, graphene aerogels have the characteristics of high temperature resistance, light weight, and corrosion resistance, and have good photothermal conversion performance; (3) The selective adsorption of salt ions by PNaSS and PMPTC materials can generate electricity through concentration difference. Using the porous material provided by the present invention in comprehensive energy utilization systems such as seawater desalination or thermal-hydro-electric co-production, the electricity generated in this part further improves the energy utilization efficiency.

[0041] The ceramic porous material of the present invention is one or more of silicon carbide, aluminum nitride, silicon nitride, aluminum oxide, zirconium oxide, titanium dioxide, phosphate, rare earth oxide, fly ash, coal gangue, kaolin, montmorillonite, and spinel in any proportion.

[0042] The ceramic porous material of the present invention is obtained by one or more of additive manufacturing, adding pore-forming agents, sacrificial template method, foaming method, sol-gel method, and fiber building method. Ceramic porous materials with different structural parameters are obtained through different preparation methods to meet the requirements of different application scenarios.

[0043] (1) Additive manufacturing: Additive manufacturing technology is an advanced manufacturing technology that manufactures and stacks discrete materials layer by layer to obtain a three-dimensional complex structure, including technologies such as selective laser sintering, three-dimensional printing, stereolithography, and free extrusion molding.

[0044] Furthermore, the methods for establishing ceramic porous material models include, but are not limited to:

[0045] (1) Use the triply periodic minimal surface method (TPMS) to establish a macroporous three-dimensional model. Equation (1) is the TPMS equation. Define the pore-skeleton interface of the porous structure as F(x, y, z) = 0, the pore region as F(x, y, z) > 0, and the solid skeleton region as F(x, y, z) < 0. In Equation (1), p and q are the characteristic parameters of the equation. p controls the pore density, and q controls the porosity. Based on this method, the porosity, pore diameter, and pore density of the ceramic porous structure model can be fixed values or can be gradient-distributed in any direction.

[0046] F(x,y,z) = ∑sin i bx·sin j by·sin k bz·cos l bx·cos m by·cos n bz + 1 = 0(1)

[0047] where i, j, k, l, m, n = 0, 1, x, y, z ∈ R 3 .

[0048] (2) Use the Kelvin cell and the Weaire-Phelan cell to construct a three-dimensional model of the porous structure. The Kelvin cell is a tetrakaidecahedron structure, including six square faces and eight regular hexagonal faces. The Weaire-Phelan cell consists of eight polyhedra, including two dodecahedra and six tetrakaidecahedra. The dodecahedron contains twelve pentagonal faces, and the tetrakaidecahedron contains twelve pentagonal faces and two hexagonal faces. Through 3D modeling software, arrange the unit cell structures of the Kelvin cell and the Weaire-Phelan cell in an array to obtain a three-dimensional model of the ceramic porous structure. The porosity and pore diameter can be adjusted by changing the size of the connecting rods of the unit cell structure.

[0049] (3) Use 3D modeling software to construct a cubic scaffold unit with a cylinder or a cuboid, and then connect the vertices of the cubic scaffolds by simple packing, body-centered packing, face-centered packing, or a combination of the above methods, and arrange them in a periodic array to construct a macroporous three-dimensional model of the porous material. The porosity and pore diameter of each unit structure can be controlled by changing the diameter of the connecting scaffolds, thereby realizing the gradient distribution of the three-dimensional pore structure parameters.

[0050] (4) Adopt the parameter random generation method to construct a disordered ceramic porous structure. The specific steps are as follows:

[0051] S1: Divide the computational domain into a number of grids, randomly generate initial growth nuclei at the grid points and label them as 1, label the solid phase as the growth phase as 1, and label the pores as the non-growth phase as 0;

[0052] S2: Given the growth probability D of each growth nucleus in different directions i , where i is the growth direction, and the growth nuclei grow towards the surrounding grid points according to the growth probability to generate new solid-phase grid points;

[0053] S3: Repeat step S2 for the new solid-phase grid points until the porosity meets the given value.

[0054] Before step S1, divide the computational region into several small regions, then perform steps S1 - S3, and give different values to the porosity and growth nuclei of each small region to achieve a gradient distribution of porosity, pore size, and pore density;

[0055] (5) Using two or more of the above four methods, based on the partition optimization strategy, construct a porous structure containing multiple local microstructures.

[0056] (2) Pore former addition method: Add a pore former to the ceramic slurry and remove the pore former through a high-temperature sintering process, thereby leaving pores in the ceramic; this method can arbitrarily adjust the addition amount of the pore former to control the porosity of the porous ceramic.

[0057] (3) Sacrificial template method: Use an organic porous structure template, impregnate it with a ceramic suspension or precursor solution, and then remove the organic template to obtain porous ceramics. This method is simple and flexible and is suitable for preparing macroporous ceramics.

[0058] (4) Foaming method: Add a foaming agent and a catalyst to the ceramic formulation, mix evenly, and then heat-treat to volatilize the additives to form a foam structure, and then obtain a porous thermal insulation material through drying and sintering processes.

[0059] (5) Sol-gel method: Mainly used for preparing nano-scale microporous ceramic materials, by increasing the viscosity to stabilize bubbles during the sol-gel technology transformation process, and is suitable for preparing highly regular foam ceramic materials.

[0060] (6) Fiber building method: Use ceramic fibers as raw materials and improve the porosity by building fiber channels layer by layer.

[0061] In this embodiment, the ceramic / graphene / PNaSS and PMPTC composite porous material provided by the present invention is used as the evaporation carrier, and its preparation method includes:

[0062] Example 1

[0063] A preparation method of a ceramic-based composite porous material, comprising the following steps:

[0064] Step 1: Establish a three-dimensional model of the "W"-type TPMS structure with a porosity of 0.35, an equivalent diameter of 0.3 mm, and a pore density of 60 PPI. Prepare the Al2O3 ceramic porous material by stereolithography additive manufacturing technology.

[0065] Step 2: Add graphene oxide powder, crosslinking agent, ethylenediamine, PNaSS, and a dilute solution of PMPTC into deionized water. By mass ratio, graphene oxide powder: crosslinking agent: ethylenediamine: PNaSS: dilute solution of PMPTC: deionized water = 0.4: 0.44: 1.2: 0.8: 0.8: 100. After stirring and mixing, a premixed solution is obtained.

[0066] Among them, the crosslinking agent is polyvinyl alcohol and sodium tetraborate, and the ratio is polyvinyl alcohol: sodium tetraborate = 1:10.

[0067] Step 3: Put the Al2O3 ceramic porous material prepared in Step 1 into the premixed solution prepared in Step 2. Place the ceramic porous material and the premixed solution in a vacuum barrel and evacuate for 4 h to allow the premixed solution to fully impregnate into the pores of the ceramic porous material, obtaining a product.

[0068] Step 4: Place the product obtained in Step 3 on a directional freezing stage and freeze it at a freezing temperature of -30 °C for 0.5 h, and then thaw it at room temperature.

[0069] Step 5: Place the product obtained in Step 4 in a reaction kettle and heat it. The hydrothermal reaction temperature is 140 °C, and the reaction time is 0.5 h.

[0070] Step 6: Repeat Steps 4 to 5 three times.

[0071] Step 7: Place the product obtained in Step 6 on a directional freezing stage and freeze it again at a freezing temperature of -30 °C for 0.5 h to obtain a frozen ceramic / graphene / PNaSS and PMPTC hydrogel.

[0072] Step 8: Place the frozen ceramic / graphene / PNaSS and PMPTC hydrogel obtained in Step 7 in a freeze-dryer for freeze-drying. The freezing temperature is -30 °C, the vacuum degree is 5 Pa, and the drying time is 48 h. After the ice crystals sublime, an anisotropic pore structure is left, obtaining the second ceramic / graphene / PNaSS and PMPTC composite porous material 27.

[0073] Furthermore, in this embodiment, a "thermal-electric-hydro" co-production integrated energy utilization system is designed, and the system schematic diagram is as shown in Figure 2As shown in the figure. The system includes: the second ceramic / graphene / PNaSS and PMPTC composite porous material 27, solar photovoltaic panel 5, thermal conductive adhesive, first condenser 6, water outlet pipe 7, first fresh water collector 8, first bottom plate 9, first seawater 10, sunlight 11, water vapor 12 and other components.

[0074] Among them, the solar photovoltaic panel 5 is located at the topmost layer of the device, responsible for capturing sunlight 11 and converting it into electric energy. At the same time, the waste heat generated by it is used for the subsequent seawater desalination process; the thermal conductive adhesive is located below the solar photovoltaic panel 5, used to effectively transfer the heat generated by the solar photovoltaic panel 5 to the second ceramic / graphene / PNaSS and PMPTC composite porous material 27 below it, and at the same time fix the position of the solar photovoltaic panel 5; the second ceramic / graphene / PNaSS and PMPTC composite porous material 27 is attached to the back of the solar photovoltaic panel 5. The second ceramic / graphene / PNaSS and PMPTC composite porous material 27 below the solar photovoltaic panel 5 absorbs the first seawater 10 through capillary action, and absorbs the waste heat generated during the operation of the solar photovoltaic panel 5 to evaporate and generate water vapor 12. After the water vapor 12 condenses, pure water is obtained; the top end of the first condenser 6 is connected to the solar photovoltaic panel 5 through a sealant, and the bottom end of the first condenser 6 is connected to the first bottom plate 9 through a sealant. The first condenser 6 is used to fix and protect the device structure, form a closed space to prevent water vapor leakage, and at the same time dissipate heat to the outside to condense the water vapor 12. The first bottom plate 9 is an aluminum alloy metal plate, which is heat-treated and in a V shape, used to support the core part of the device and form a fresh water flow channel for collecting fresh water conveniently. A water outlet pipe 7 is arranged at the lowermost part of the side wall surface of the first condenser 6, and an opening is made on the first condenser 6 and connected to the water outlet through a sealant, used to discharge and collect the condensed water. A first fresh water collector 8 is placed below the water outlet, used to collect the fresh water flowing out of the water outlet.

[0075] Taking the second ceramic / graphene / PNaSS and PMPTC composite porous material 27 provided in Embodiment 1 of the present invention as the evaporation carrier can simultaneously meet the cooling and desalting requirements. Its small pores have rich capillary forces to provide sufficient water supply, while the large pores provide a place for the convection of salts to slow down salt crystallization. The stable chemical properties of the graphene aerogel / ceramic cross-scale porous material have excellent corrosion resistance, further improving the stability of the seawater desalination and utilization system. In addition, the concentration difference power generation can be carried out by using the selective adsorption effect of PNaSS and PMPTC materials on salt ions, and the power generation of this part further improves the utilization efficiency of solar energy.

[0076] Embodiment 2

[0077] A preparation method of a ceramic-based composite porous material includes the following steps:

[0078] Step 1: Establish a three-dimensional model of the "G"-type TPMS structure with a porosity of 0.8, an equivalent diameter of 0.3 mm, and a pore density of 20 PPI. Prepare the SiC ceramic porous material by the sacrificial template method;

[0079] Step 2: Add graphene oxide powder, sodium tetraborate, sodium ascorbate, PNaSS, and a dilute solution of PMP TC to deionized water. By mass ratio, graphene oxide powder: sodium tetraborate: sodium ascorbate: PNaSS: dilute solution of PMP TC: deionized water = 0.3: 0.03: 1: 1: 1: 100. After stirring and mixing, a premixed solution is obtained;

[0080] Step 3: Put the SiC ceramic porous material prepared in Step 1 into the premixed solution prepared in Step 2. Place the ceramic porous material and the premixed solution in a vacuum barrel and evacuate to allow the premixed solution to fully impregnate the pores of the ceramic porous material. The evacuation time is 12 h to obtain the product;

[0081] Step 4: Freeze the product obtained in Step 3 on a directional freezing stage at a freezing temperature of -10 °C for 10 h to obtain a frozen ceramic / graphene / PNaSS and PMPTC hydrogel;

[0082] Step 5: Freeze-dry the frozen ceramic / graphene / PNaSS and PMPTC hydrogel obtained in Step 4 in a freeze-dryer at a freezing temperature of -40 °C, a vacuum degree of 1 Pa, and a drying time of 12 h. After the ice crystals sublime, an anisotropic pore structure is left to obtain the third ceramic / graphene / PNaSS and PMPTC composite porous material 13.

[0083] Furthermore, in Example 2 of the present invention, a seawater desalination and concentration difference power generation system is designed with the third ceramic / graphene / PNaSS and PMPTC composite porous material 13 prepared in Step 5 as the evaporation carrier. The schematic diagram of the principle is as Figure 3 shown. This system includes components such as the third ceramic / graphene / PNaSS and PMPTC composite porous material 13 as the evaporation carrier, the second seawater 14, the electrode 15, the fresh water 16, the second condenser cover 17, the water outlet 18, and the second fresh water collector 19.

[0084] Among them, the bottom of the second condenser cover 17 is connected to the third ceramic / graphene / PNaSS and PMPTC composite porous material 13 and fixed by sealant. The third ceramic / graphene / PNaSS and PMPTC composite porous material 13 absorbs the second seawater 14 through capillary action, filling the entire evaporation carrier with seawater. An opening is made at the bottom of the side of the second condenser cover 17 and connected to the water outlet 18 through sealant. A second fresh water collector 19 is placed below the water outlet 18; the upper surface of the third ceramic / graphene / PNaSS and PMPTC composite porous material 13 is fixed with an electrode 15 by soldering, and the electrode 15 is a copper electrode. When the system operates, sunlight passes through the second condenser cover 17 and shines on the upper surface of the evaporation carrier. The evaporation carrier absorbs sunlight and converts it into heat energy, promoting the evaporation of water on the surface of the evaporation carrier. The generated water vapor condenses on the inner surface of the second condenser cover 17, and the condensed fresh water 16 flows along the solid wall surface of the second condenser cover 17 to the bottom of the second condenser cover 17 and flows from the water outlet 18 to the second fresh water collector 19; electric energy is generated simultaneously during the water evaporation process.

[0085] The third ceramic / graphene / PNaSS and PMPTC composite porous material 13 provided by the present invention includes a nano-scale to millimeter-scale cross-scale pore structure and has a natural salt rejection advantage. Its small pores have abundant capillary force to provide sufficient water supply, while the large pores provide a place for the convection of salts. The stable chemical properties of the third ceramic / graphene / PNaSS and PMPTC composite porous material 13 have excellent corrosion resistance, further improving the stability of the seawater desalination and utilization system. The PNaSS and PMPTC materials have a selective adsorption effect on salt ions. The PNaSS chain itself carries a negative charge and is more likely to attract sodium ions Na + ,a large number of sodium ions Na + are adsorbed in the porous material channels, causing the charge sign on the channel surface to be reversed, that is, showing a positive charge. At this time, negatively charged counterions will be attracted into the channel, and the continuous passage of a large number of counterions can generate streaming potential. The selective passage of salt ions through the charged channels further slows down salt crystallization, making the porous material prepared by the present invention have excellent corrosion resistance characteristics.

[0086] Example 3

[0087] A preparation method of a ceramic-based composite porous material includes the following steps:

[0088] Step 1: Prepare a Si3N4 ceramic porous material by the foam method;

[0089] Step 2: Add graphene oxide powder, glutaraldehyde, and ammonium sulfide to deionized water. By mass ratio, graphene oxide powder: glutaraldehyde: ammonium sulfide: deionized water = 5:5:12.5:100. After stirring and mixing, a premixed solution is obtained;

[0090] Step 3: Place the Si3N4 ceramic porous material prepared in Step 1 into the premixed solution prepared in Step 2. Place the ceramic porous material and the premixed solution in a vacuum chamber and evacuate to allow the premixed solution to fully impregnate the pores of the ceramic porous material. The evacuation time is 0.5 h;

[0091] Step 4: Place the product obtained in Step 3 in a reaction kettle and heat it. The hydrothermal reaction temperature is 160 °C and the reaction time is 2.5 h to obtain a ceramic / graphene hydrogel;

[0092] Step 5: Freeze the ceramic / graphene hydrogel obtained in Step 4 at -30 °C; the freezing time is 8 h to obtain a frozen ceramic / graphene hydrogel;

[0093] Step 6: Place the frozen ceramic / graphene hydrogel from Step 5 in a freeze-dryer for freeze-drying. The freezing temperature is -35 °C, the vacuum degree is 2 Pa, and the drying time is 40 h. After the ice crystals sublime, an anisotropic pore structure is left to obtain the ceramic / graphene composite porous material 20.

[0094] Furthermore, the present invention designs a thermal protection structure as Figure 4 shown. The thermal protection structure mainly includes: ceramic / graphene composite porous material 20, reinforcing ribs 21, fairing 22, second bottom plate 23, pipeline 24, flowing working fluid inlet 25, heat load 26, etc.

[0095] The ceramic / graphene composite porous material 20 prepared in Step 6 is located between the reinforcing ribs 21, and the side surface of the ceramic / graphene composite porous material 20 is connected to the reinforcing ribs 21 through a heat-conducting adhesive; the rectifying chamber 22 is in direct contact with the bottom of the ceramic / graphene composite porous material 20, and both sides of the rectifying chamber 22 are connected to the reinforcing ribs 21 by welding; the second bottom plate 23 is located at the bottom of the reinforcing ribs 21 and the rectifying chamber 22, and the second bottom plate 23 is connected to the reinforcing ribs 21 by welding; holes are opened on the second bottom plate 23, and the openings are connected to the pipeline 24 by welding. The flowing working fluid enters the pipeline 24 from the flowing working fluid inlet 25. The rectifying chamber 22 is filled with hydrophilic stacked fibers. The fiber material sucks the flowing working fluid in the pipeline 24 into the rectifying chamber 22 through capillary action. The ceramic / graphene composite porous material 20 sucks the flowing working fluid in the rectifying chamber 22 to the outer surface through capillary action. When the outer surface is subjected to a heat load 26, the flowing working fluid absorbs heat and undergoes a gas-liquid phase change to take away the heat, achieving the cooling purpose. Taking the ceramic / graphene composite porous material 20 prepared in Step 6 as the evaporation carrier, on the one hand, the pores of the customized large-scale ceramic skeleton and the pores generated by the directional freeze-drying of the graphene aerogel are utilized to make the fluid transport along the specified path. Taking thermal management as an example, more coolant can be transported to the position with a higher heat flux density, greatly improving the cooling efficiency and the critical heat flux density; on the other hand, the capillary action of the small-scale pores is utilized to drive the fluid flow without additional power; the porous material provided by the present invention simultaneously includes millimeter-scale, micron-scale, and nanoscale pore structures, has strong capillary action and good permeability, and overcomes the disadvantage that the capillary action and permeability cannot be both achieved in a porous material with a uniform pore size.

[0096] The porous material proposed by the present invention simultaneously has the advantages of ultra-light weight, high porosity, pore sizes ranging from nanoscale to millimeter scale, wide pore size distribution range, and adjustable pore structure characteristics. The pore size distribution is as Figure 5 shown, and it simultaneously includes pores smaller than 10 microns, 10 - 100 microns, and larger than 100 microns. The electron micrograph of the pores is as Figure 6 shown. The vertical channels in the figure are the micron-scale directional pores generated by directional freeze-drying, and the stacking between the graphene sheets forms pores smaller than micron scale. The size and distribution of the pores can be freely adjusted by controlling the freezing temperature and freezing time. The ultra-light characteristic of the graphene material makes the composite pore material have high porosity and ultra-light weight at the same time. On the one hand, the extremely strong capillary action of the small pores improves the critical heat flux density of cooling. On the other hand, the lower flow resistance of the large pores provides a channel for the escape of steam, avoiding steam blockage. Therefore, the porous material of the present invention has a higher critical heat flux density of cooling than a porous material with a single pore size, that is, it has higher cooling efficiency. Therefore, the porous material prepared by the present invention can be applied in high-temperature and high-heat flux density environments to meet the requirements of higher temperature application scenarios.

[0097] Example 4

[0098] A preparation method of a ceramic matrix composite porous material, comprising the following steps:

[0099] Step 1: Add a pore-forming agent to the zirconia ceramic slurry, and remove the pore-forming agent through a high-temperature sintering process to form a zirconia ceramic porous material;

[0100] Step 2: Add graphene oxide powder, stearic acid, ammonia water, PNaSS and PMPTC dilute solution to deionized water. By mass ratio, graphene oxide powder: stearic acid: ammonia water: PNaSS: PMPTC dilute solution: deionized water = 0.35: 0.35: 5: 30: 30: 100. After stirring and mixing, a premixed solution is obtained;

[0101] Step 3: Put the Al2O3 ceramic porous material prepared in Step 1 into the premixed solution prepared in Step 2. Place the ceramic porous material and the premixed solution in a vacuum barrel and evacuate for 4 h to allow the premixed solution to fully impregnate into the pores of the ceramic porous material to obtain a product;

[0102] Step 4: Freeze the product obtained in Step 3 on a directional freezing table at a freezing temperature of -196 °C for 0.2 h, and then thaw at room temperature;

[0103] Step 5: Place the product obtained in Step 4 in a reaction kettle and heat it. The hydrothermal reaction temperature is 60 °C and the reaction time is 12 h;

[0104] Step 6: Repeat Steps 4 to 5 twice;

[0105] Step 7: Freeze the product obtained in Step 6 on a directional freezing table again at a freezing temperature of -196 °C for 0.2 h to obtain a frozen ceramic / graphene / PNaSS and PMPTC hydrogel;

[0106] Step 8: Place the frozen ceramic / graphene / PNaSS and PMPTC hydrogel obtained in Step 7 in a freeze dryer for freeze-drying. The freezing temperature is -40 °C, the vacuum degree is 4 Pa, and the drying time is 240 h. After the ice crystals sublimate, an anisotropic pore structure is left to obtain a fourth ceramic / graphene / PNaSS and PMPTC composite porous material.

[0107] Example 5

[0108] A preparation method of a ceramic matrix composite porous material, comprising the following steps:

[0109] Step 1: Using 3D modeling software, construct cubic scaffold units with cylinders or cuboids, then connect the vertices of the cubic scaffolds by simple stacking, body-centered cubic stacking, face-centered cubic stacking, or a combination of the above methods, and construct a macroporous three-dimensional model of the porous material by periodic array arrangement, and prepare an aluminum nitride ceramic porous material through a photocuring additive manufacturing technique;

[0110] Step 2: Add graphene oxide powder, sodium tetraborate, ethylenediamine, PNaSS, and a dilute solution of PMPTC to deionized water. By mass ratio, graphene oxide powder: sodium tetraborate: ethylenediamine: deionized water = 0.5: 0.5: 1.3: 100. After stirring and mixing, obtain a premixed solution;

[0111] Step 3: Put the Al2O3 ceramic porous material prepared in Step 1 into the premixed solution prepared in Step 2. Place the ceramic porous material and the premixed solution in a vacuum barrel and evacuate for 1 h to allow the premixed solution to fully impregnate the pores of the ceramic porous material to obtain a product;

[0112] Step 4: Place the product obtained in Step 3 on a directional freezing table and freeze it at a freezing temperature of -35 °C for 0.5 h, and then thaw it at room temperature;

[0113] Step 5: Place the product obtained in Step 4 in a reaction kettle and heat it. The hydrothermal reaction temperature is 100 °C and the reaction time is 2 h;

[0114] Step 6: Repeat Steps 4 to 5 three times;

[0115] Step 7: Place the product obtained in Step 6 on a directional freezing table and freeze it again at a freezing temperature of -10 °C for 10 h to obtain a frozen ceramic / graphene hydrogel;

[0116] Step 8: Place the frozen ceramic / graphene hydrogel obtained in Step 7 in a freeze-dryer for freeze-drying. The freezing temperature is -40 °C, the vacuum degree is 4 Pa, and the drying time is 96 h. After the ice crystals sublime, an anisotropic pore structure is left to obtain a fifth ceramic / graphene composite porous material.

[0117] The porous material provided by the present invention has the characteristics of ultra-light weight, high temperature resistance, corrosion resistance, high porosity, wide pore size distribution range, adjustable pore structure characteristics, etc., and at the same time solves the following technical problems:

[0118] 1. In the field of evaporative cooling: problems such as uneven coolant flow distribution and local ablation have been solved. The local heat load borne by the sweating carrier in the leading edge structure is seriously mismatched with the cooling amount, resulting in local ablation, which is one of the main obstacles limiting the efficiency of phase change evaporative cooling and the improvement of the ultimate heat flux density; while phase change evaporative cooling brings high cooling capacity, the unstable phase change process inside the porous medium will cause serious steam blockage and large temperature oscillations. In the field of microelectronic device cooling, the uneven temporal and spatial distribution of heat load will also lead to similar problems mentioned above in the phase change heat transfer process inside the porous medium.

[0119] The porous material provided by the present invention, on the one hand, utilizes customized large-scale pores to transmit liquid coolant and steam along a specified path, so that more coolant is transported to locations with higher heat flux density, greatly improving cooling efficiency and limiting heat flux density; on the other hand, it utilizes the capillary suction effect of small-scale pores to achieve adaptive matching between coolant flow and dynamically changing heat load, thereby alleviating steam blockage and temperature oscillation.

[0120] 2. In the field of seawater desalination: the problem of salt accumulation blocking the evaporation surface has been solved. The salt removal problem has always been the main problem that plagued traditional interface evaporation seawater desalination technology. During the evaporation of seawater, the salt concentration at the evaporation interface increases, and salt crystals block the evaporation surface, resulting in low evaporation efficiency and shortening the service life of the seawater desalination system. Its dependence on a large amount of energy, high initial investment and operation and maintenance costs constitute application barriers in areas with obvious resource constraints or insufficient energy conditions.

[0121] The porous material provided by the present invention comprises a cross-scale pore structure from millimeter to nanometer scale, and has a natural advantage in salt removal. Its small pores have abundant capillary force, providing sufficient water supply, while the large pores provide a place for salt convection. The stable chemical properties of the ceramic / graphene / PNaSS and PMPTC cross-scale porous materials have excellent corrosion resistance, further improving the stability of the seawater desalination system. In addition, the oppositely charged poly (sodium p-styrene sulfonate) (PNaSS) and poly (3-methyl 2-methyl propylene acrylamide-ammonium chloride) (PMPTC) materials have a selective adsorption effect on salt ions. The PNaSS chain itself has a negative charge, which is more likely to attract sodium ions Na + , a large amount of sodium ions Na +Adsorbed in the pores of the porous material, the charge sign on the channel surface is reversed, showing a positive charge. At this time, negatively charged counterions will be attracted into the channel, and the continuous passage of a large number of counterions can generate streaming potential. The salt ions selectively pass through the charged channels, further slowing down the increase in the salt molecule concentration, thereby avoiding salt crystallization and further improving the anti-salt crystallization performance of the entire seawater desalination system. The ceramic / graphene / PNaSS and PMPTC cross-scale porous materials continuously and rapidly replenish water from the hydrophilic hydrogel network and hierarchical porous channels through capillary force. At the microscale, water molecules in the bound state exist near the ionic groups of the porous material through hydrogen bonds, while water molecules far from the polymer chains exhibit the same properties as bulk water. Between the bound water and free water, there is intermediate water with weak hydrogen bonds or non-hydrogen bonds, and it has been proven that the intermediate water is more likely to evaporate than free water.

[0122] 3. In the field of comprehensive energy utilization: The problem of low energy utilization efficiency is solved.

[0123] In the present invention, by integrating the seawater desalination system with the photovoltaic power generation system, high-energy photons during the solar radiation process are used for photovoltaic power generation, while the thermal energy generated by other low-energy photons is used for the seawater desalination process. Most importantly, not only fresh water is produced during the seawater desalination process, but the gas-liquid phase change process also provides cooling for the photovoltaic panels. Therefore, the integrated design strategy of the photovoltaic power generation-evaporation cooling-seawater desalination multi-functional energy utilization system becomes a key scientific issue. And the evaporation carrier, as the core component providing cooling capacity and fresh water vapor, its material and pore structure directly determine the efficiency of the entire energy utilization system. The present invention fundamentally solves this problem.

Claims

1. A preparation method of a ceramic matrix composite porous material, characterized in that, It includes the following steps: Step 1: Add graphene oxide powder, crosslinking agent, reducing agent, dilute solution of PNaSS and PMPTC into deionized water, and stir and mix them to obtain a premixed solution; By mass ratio, graphene oxide powder: crosslinking agent: reducing agent: PNaSS: dilute solution of PMPTC: deionized water = (0.3 - 5):(0.03 - 5):(1 - 12.5):(0 - 30):(0 - 30):100; Step 2: Immerse the ceramic porous material into the premixed solution prepared in Step 1, place the ceramic porous material and the premixed solution in a vacuum barrel and evacuate to make the premixed solution fully impregnate into the pores of the ceramic porous material to obtain a product; Step 3: Directionally freeze the product obtained in Step 2 to obtain a directional product; The directional freezing specifically is: The freezing temperature is from -10°C to -196°C, and the freezing time is 0 - 10 h; Step 4: Thaw the directional product obtained in Step 3 at room temperature, and then carry out a hydrothermal reaction. If the freezing in Step 3 is not carried out, carry out a hydrothermal reaction on the product obtained in Step 2. The hydrothermal reaction temperature is 60 - 160°C, and the reaction time is 0 - 12 h. If the hydrothermal reaction time is 0, skip the thawing and jump to Step 7; Step 5: Repeat Steps 3 to 4 for 0 - 3 times; if the freezing time in Step 3 is 0, skip Step 5; Step 6: Freeze the product obtained in Step 5 again. If Step 5 is skipped, freeze the product in Step 4. If the hydrothermal reaction time in Step 4 is 0, freeze the product obtained in Step 2 to obtain a frozen ceramic / graphene / PNaSS and PMPTC hydrogel; Step 7: Carry out freeze-drying on the frozen ceramic / graphene / PNaSS and PMPTC hydrogel in Step 6. If the hydrothermal reaction time in Step 4 is 0, carry out freeze-drying on the product in Step 3. The freeze-drying temperature is from -30°C to -40°C, and the freeze-drying time is 12 - 240 h. After the ice crystals sublime, an anisotropic pore structure is left to obtain a ceramic / graphene / PNaSS and PMPTC composite porous material.

2. The preparation method of a ceramic matrix composite porous material according to claim 1, characterized in that, The ceramic porous material in Step 2 is one or more of silicon carbide, aluminum nitride, silicon nitride, alumina, zirconia, titanium dioxide, phosphate, rare earth oxide, fly ash, coal gangue, kaolin, montmorillonite, spinel in any proportion.

3. The preparation method of a ceramic matrix composite porous material according to claim 1, characterized in that, The crosslinking agent in Step 1 is one or more of sodium tetraborate, polyvinyl alcohol, stearic acid, cysteine, glutaraldehyde, DNA molecular chain in any proportion; the reducing agent is one or more of ethylene diamine, sodium ascorbate, ammonium sulfide, ammonia water, diethylenetriamine, sodium bisulfite, sodium sulfide, thiourea, hydroiodic acid, hydrazine hydrate in any proportion.

4. The preparation method of a ceramic matrix composite porous material according to claim 1, characterized in that, In Step 2, the vacuum evacuation time is 0.5 - 12 h.

5. The preparation method of a ceramic matrix composite porous material according to claim 1, characterized in that, In Step 6, the freezing temperature is from -10°C to -196°C, and the freezing time is 0.1 - 10 h.

6. The preparation method of a ceramic matrix composite porous material according to claim 1, characterized in that, It includes the following steps: Step 1: Establish a three-dimensional model of a porous structure with a porosity of 0.35, an equivalent diameter of 0.3 mm, and a pore density of 60 PPI, and prepare an Al2O3 ceramic porous material by stereolithography additive manufacturing technology; Step 2: Add graphene oxide powder, crosslinking agent, ethylenediamine, PNaSS, and dilute PMPTC solution into deionized water. By mass ratio, graphene oxide powder: crosslinking agent: ethylenediamine: PNaSS: dilute PMPTC solution: deionized water = 0.4: 0.44: 1.2: 0.8: 0.8:

100. After stirring and mixing, a premixed solution is obtained; Among them, the crosslinking agent is polyvinyl alcohol and sodium tetraborate, and the ratio is polyvinyl alcohol: sodium tetraborate = 1:10; Step 3: Put the Al2O3 ceramic porous material prepared in Step 1 into the premixed solution prepared in Step 2. Place the ceramic porous material and the premixed solution in a vacuum barrel and evacuate for 4 h to allow the premixed solution to fully impregnate into the pores of the ceramic porous material, obtaining a product; Step 4: Place the product obtained in Step 3 on a directional freezing table and freeze it. The freezing temperature is -30 °C, and the freezing time is 0.5 h. Then thaw it at room temperature; Step 5: Place the product obtained in Step 4 in a reaction kettle and heat it. The hydrothermal reaction temperature is 140 °C, and the reaction time is 0.5 h; Step 6: Repeat Steps 4 to 5 three times; Step 7: Place the product obtained in Step 6 on a directional freezing table and freeze it again. The freezing temperature is -30 °C, and the freezing time is 0.5 h, obtaining a frozen ceramic / graphene / PNaSS and PMPTC hydrogel; Step 8: Place the frozen ceramic / graphene / PNaSS and PMPTC hydrogel obtained in Step 7 in a freeze dryer for freeze-drying. The freezing temperature is -30 °C, the vacuum degree is 5 Pa, and the drying time is 48 h. After the ice crystals sublime, an anisotropic pore structure is left, obtaining the second ceramic / graphene / PNaSS and PMPTC composite porous material 27.

7. The preparation method of a ceramic matrix composite porous material according to claim 1, characterized in that, Including the following steps: Step 1: Establish a three-dimensional model of the porous structure with a porosity of 0.8, an equivalent diameter of 0.3 mm, and a pore density of 20 PPI. Prepare a SiC ceramic porous material by the sacrificial template method; Step 2: Add graphene oxide powder, sodium tetraborate, ascorbic acid sodium, PNaSS, and dilute PMP TC solution into deionized water. By mass ratio, graphene oxide powder: sodium tetraborate: ascorbic acid sodium: PNaSS: dilute PMPTC solution: deionized water = 0.3: 0.03: 1: 1: 1:

100. After stirring and mixing, a premixed solution is obtained; Step 3: Put the SiC ceramic porous material prepared in Step 1 into the premixed solution prepared in Step 2. Place the ceramic porous material and the premixed solution in a vacuum barrel and evacuate to allow the premixed solution to fully impregnate into the pores of the ceramic porous material. The evacuation time is 12 h, obtaining a product; Step 4: Place the product obtained in Step 3 on a directional freezing table and freeze it. The freezing temperature is -10 °C, and the freezing time is 10 h, obtaining a frozen ceramic / graphene / PNaSS and PMPTC hydrogel; Step 5: Place the ceramic / graphene / PNaSS and PMPTC hydrogels frozen in Step 4 into a freeze dryer for freeze drying. The freezing temperature is -40 °C, the vacuum degree is 1 Pa, and the drying time is 12 h. After the ice crystals sublime, an anisotropic pore structure is left, and the third ceramic / graphene / PNaSS and PMPTC composite porous material 13 is obtained.

8. The preparation method of a ceramic matrix composite porous material according to claim 1, characterized in that, It includes the following steps: Step 1: Prepare a Si3N4 ceramic porous material by the foam method; Step 2: Add graphene oxide powder, glutaraldehyde, and ammonium sulfide to deionized water. By mass ratio, graphene oxide powder: glutaraldehyde: ammonium sulfide: deionized water = 5:5:12.5:

100. After stirring and mixing, a premixed solution is obtained; Step 3: Put the Si3N4 ceramic porous material prepared in Step 1 into the premixed solution prepared in Step 2. Place the ceramic porous material and the premixed solution in a vacuum barrel and evacuate to make the premixed solution fully impregnate into the pores of the ceramic porous material. The evacuation time is 0.5 h; Step 4: Place the product obtained in Step 3 into a reaction kettle and heat it. The hydrothermal reaction temperature is 160 °C, and the reaction time is 2.5 h to obtain a ceramic / graphene hydrogel; Step 5: Freeze the ceramic / graphene hydrogel obtained in Step 4 at -30 °C; the freezing time is 8 h to obtain a frozen ceramic / graphene hydrogel; Step 6: Place the frozen ceramic / graphene hydrogel in Step 5 into a freeze dryer for freeze drying. The freezing temperature is -35 °C, the vacuum degree is 2 Pa, and the drying time is 40 h. After the ice crystals sublime, an anisotropic pore structure is left, and the ceramic / graphene composite porous material 20 is obtained.

9. A ceramic matrix composite porous material, characterized in that, Obtained by any one of the preparation methods of Claims 1 to 8.

10. Application of the ceramic matrix composite porous material obtained by any one of the preparation methods of Claims 1 to 8 or the ceramic matrix composite porous material described in Claim 9, wherein the ceramic matrix composite porous material is applied to the field of evaporative cooling or the field of seawater desalination or the field of comprehensive energy utilization.

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