Preparation method of carbon fiber ceramic body and porous ceramic heating element

Abstract

The present invention relates to a method for preparing a carbon fiber ceramic body and a porous ceramic heating element. The method for preparing a carbon fiber ceramic body comprises the following steps: adding ceramic powder, adhesive, and surfactant to silica sol to form a slurry and ball milling to form three slurries, respectively adding 5%, 10%, and 15% of chopped fibers and pore formers and water to the three slurries, and ball milling to form a first mixture, a second mixture, and a third mixture. The ceramic powder of the present invention can form a structural skeleton, the adhesive can bond the ceramic powder, and the pore former can form pores; the surfactant can enhance the dispersion of pores in the ceramic powder and the adhesive; the chopped fibers can enhance the strength of the carbon fiber ceramic body; the chopped fibers will produce carbon after being heated and decomposed, which can increase the thermal conductivity of the carbon fiber ceramic body; and the content of the chopped fibers in the first mixture, the second mixture, and the third mixture gradually increases, which can make the heat distribution of the carbon fiber ceramic body uniform.

Description

Technical Field

[0001] The invention relates to the technical field of heating elements, and in particular to a method for preparing a carbon fiber ceramic body and a porous ceramic heating element. Background Art

[0002] An electronic atomization device is a device that produces inhalable aerosol by heating atomized liquid. It is mainly used as a smoking substitute or a medical suction device, and usually includes an atomization component, a battery component, etc.

[0003] As the core component of the electronic atomization device, the atomization component is closely related to the atomization effect of the entire device. At present, the atomization components of some electronic atomization devices use ceramic atomization components, which mainly include a porous ceramic body and a heating element. The heating element is usually printed and sintered on the surface of the porous ceramic body by thick film printing. Due to its good lipophilicity and porous structure, the porous ceramic body can quickly absorb the atomized liquid and conduct it to the surface where the heating element is located, so that the heating element can heat and atomize to form an inhalable aerosol.

[0004] However, the existing ceramic atomization components are prone to uneven printing when printing heating slurry on the porous ceramic body, which causes uneven heating of the heating body during operation, easily causing local overtemperature and uneven atomization, affecting the atomization effect. Summary of the invention

[0005] Based on this, it is necessary to provide a method for preparing a carbon fiber ceramic body and a porous ceramic heating element that can ensure uniform heat distribution, effectively avoid the phenomenon of local excessive temperature, and ensure atomization effect and taste.

[0006] A method for preparing a carbon fiber ceramic body, the method comprising the following steps:

[0007] S110, adding ceramic powder, adhesive, and surfactant to silica sol to form a slurry and performing ball milling to form three slurries, respectively adding 5%, 10%, and 15% of chopped fibers, a pore-forming agent, and water to the three slurries, and performing ball milling to form a first mixture, a second mixture, and a third mixture;

[0008] S120, pouring the third mixed material, the second mixed material, and the first mixed material into a mold in sequence to obtain a raw material slurry;

[0009] S130, keeping the mold containing the raw material slurry warm in liquid nitrogen, and then demoulding to obtain an embryo body;

[0010] S140, pyrolyzing the embryo body in a nitrogen atmosphere, and sintering the pyrolyzed embryo body to prepare the carbon fiber ceramic body.

[0011] In one embodiment, step S110 specifically includes:

[0012] The ceramic powder, the adhesive, and the surfactant are added to the silica sol to prepare a first slurry and ball-mill the slurry; then a pore former, 5% of chopped fibers, and water are added to the first slurry after ball milling to prepare a first mixture, and the first mixture is ball-milled;

[0013] The ceramic powder, the adhesive, and the surfactant are added to the silica sol to prepare a second slurry, and the second slurry is ball-milled; then, the pore former, 10% of the chopped fibers, and the water are added to the second slurry after ball milling to prepare a second mixture, and the second mixture is ball-milled;

[0014] The ceramic powder, the adhesive, and the surfactant are added to the silica sol to prepare a third slurry, and the third slurry is ball-milled; then, the pore-forming agent, 15% of the chopped fibers, and the water are added to the third slurry after ball milling to prepare a third mixture, and the third mixture is ball-milled.

[0015] In one embodiment, the amount of the ceramic powder added to the first slurry is 30% to 35% of the mass of the silica sol; the amount of the ceramic powder added to the second slurry is 25% to 30% of the mass of the silica sol; and the amount of the ceramic powder added to the third slurry is 20% to 25% of the mass of the silica sol.

[0016] In one embodiment, the mass percentage of the adhesive is 1% to 2%, the mass percentage of the surfactant is 1% to 2%, and the mass percentage of the pore-forming agent is 2% to 3%.

[0017] In one embodiment, the embryo is kept warm in liquid nitrogen for 0.8 h to 1.2 h, and the temperature at which the embryo is kept warm in liquid nitrogen is -40°C to -45°C; the embryo is pyrolyzed in a nitrogen atmosphere for 3 h to 4 h, and the temperature at which the embryo is pyrolyzed in a nitrogen atmosphere is 400°C to 800°C; the embryo is sintered at a temperature of 1000°C to 1700°C.

[0018] In one of the embodiments, the temperature of sintering the embryo is 1000° C. to 1700° C., and the holding time of sintering the embryo is 2 h to 5 h.

[0019] In one embodiment, the thickness of the third mixture, the second mixture and the first mixture in the mold gradually increases. In one embodiment, the number of micropores of the third mixture, the second mixture and the first mixture gradually decreases; the pores of the micropores of the third mixture, the second mixture and the first mixture gradually increase.

[0020] In one embodiment, the chopped fibers include one or more of organic cotton, kapok fiber, polyethylene foam (PE foam), polypropylene cotton (PP cotton), polyethylene terephthalate fiber (PET fiber), and polyamide fiber (PA).

[0021] The present application also provides a porous ceramic heating element, comprising:

[0022] The carbon fiber ceramic body is prepared by the method for preparing the carbon fiber ceramic body as described above;

[0023] The heating net is arranged on the carbon fiber ceramic body and is in contact with the third mixed material.

[0024] In the above scheme, by adding ceramic powder, adhesive, surfactant, pore-forming agent, chopped fibers and water, the ceramic powder can form a structural skeleton, the adhesive can bond the ceramic powder, and the pore-forming agent can form pores to ensure the porosity of the carbon fiber ceramic body; the surfactant can enhance the dispersion of pores in the ceramic powder and the adhesive, so that the pore distribution of the carbon fiber ceramic body is uniform; the addition of chopped fibers can improve the strength of the carbon fiber ceramic body; by pyrolyzing the embryo, the chopped fibers will produce carbon, liquid oil and gas after heating and decomposition, the liquid oil and gas can be discharged to the outside through the porous embryo, and the carbon produced after the chopped fibers are heated and decomposed will be retained in the embryo, which can increase the thermal conductivity of the carbon fiber ceramic body; and the content of chopped fibers in the first mixture, the second mixture and the third mixture gradually increases, so that the thermal conductivity of the first mixture, the second mixture and the third mixture gradually increases, which can make the heat distribution of the carbon fiber ceramic body uniform, effectively avoid the phenomenon of local excessive temperature, and ensure the atomization effect and taste. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a front view structural diagram of a porous ceramic heating element shown in one embodiment of the present invention;

[0026] Figure 2 A schematic diagram of the structure of a porous ceramic heating element according to an embodiment of the present invention;

[0027] Figure 3 This is a structural schematic diagram of a carbon fiber ceramic body and a mold according to an embodiment of the present invention;

[0028] Figure 4 This is a flowchart of a method for preparing a carbon fiber ceramic body according to an embodiment of the present invention.

[0029] Description of Reference Numerals

[0030] 10. carbon fiber ceramic body; 100. first mixed material; 200. second mixed material; 300. third mixed material; 400. mold;

[0031] 20. Porous ceramic heating element; 500. Heating net. DETAILED DESCRIPTION

[0032] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0033] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0034] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0035] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0037] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only implementation method.

[0038] See also Figure 1 , Figure 3 and Figure 4 One embodiment of the present invention provides a method for preparing a carbon fiber ceramic body 10, comprising the following steps:

[0039] S110, adding ceramic powder, adhesive, and surfactant to silica sol to form a slurry and ball-milling to form three slurries, adding 5%, 10%, and 15% of chopped fibers, pore-forming agent, and water to the three slurries respectively, and ball-milling to form a first mixture 100, a second mixture 200, and a third mixture 300.

[0040] The role of ceramic powder is to form a structural skeleton. The role of the adhesive is to bond the ceramic powder. The role of the pore former is to form pores. The role of the surfactant is to enhance the dispersion of the pore former in the ceramic powder and the low-temperature glass powder, so that the pore distribution in the ceramic powder and the low-temperature glass powder is more uniform.

[0041] It should be understood that the silica sol in step S110 is a dispersion of nano-scale silica particles in water or solvent. Specifically, the mass percentage of silica is 10% to 15%. The particle size of the silica particles is not limited in this application and can be set according to the use requirements. For example, the particle size of the silica particles is 580nm. The mass percentage of silica is 10%.

[0042] The length of the chopped fibers in step S110 is 1 mm to 15 mm. The length of the chopped fibers is not limited in this application and can be set according to the use requirements. For example, the length of the chopped fibers is 3 mm. The time for ball milling the slurry and the mixture in step S110 is not limited in this application and can be set according to actual conditions. For example, the time for ball milling the slurry is 12 hours, and the time for ball milling the mixture is 2 hours.

[0043] In one embodiment, the amount of water added to the first mixture 100, the second mixture 200 and the third mixture 300 is 50% of the volume of the slurry. In another embodiment, the amount of water added to the first mixture 100, the second mixture 200 and the third mixture 300 is 50% of the volume of the slurry to which the pore former and the chopped fibers are added.

[0044] In yet another embodiment, the amount of water added to the first mixture 100 , the second mixture 200 , and the third mixture 300 is not limited, and a proper amount of water can be added according to usage requirements.

[0045] S120, pour the third mixture 300, the second mixture 200, and the first mixture 100 into the mold 400 in sequence to obtain a raw material slurry. It should be understood that after the third mixture 300 is poured into the mold 400, the surface needs to be scraped flat, and then the second mixture 200 is poured into the mold 400. After the second mixture 200 is poured into the mold 400, the surface also needs to be scraped flat, and then the first mixture 100 is poured into the mold 400.

[0046] It should be noted that the amount of the third mixed material 300, the second mixed material 200 and the first mixed material 100 poured into the mold 400 is not limited in this application and can be set according to actual use requirements. The amount of the third mixed material 300, the second mixed material 200 and the first mixed material 100 poured into the mold 400 can also be understood as the thickness of the third mixed material 300, the second mixed material 200 and the first mixed material 100 poured into the mold 400. Among them, the thickness of the third mixed material 300 is less than the thickness of the second mixed material 200 and the first mixed material 100.

[0047] S130, the mold 400 containing the raw material slurry is kept warm in liquid nitrogen, and then demolded to obtain an embryo body. It should be understood that due to the extremely low temperature of liquid nitrogen, the first mixture 100, the second mixture 200 and the third mixture 300 in the mold 400 will be completely frozen at low temperature.

[0048] S140, pyrolyzing the embryo in a nitrogen atmosphere, and sintering the pyrolyzed embryo to produce a carbon fiber ceramic body 10. It should be understood that the pyrolysis process needs to be carried out in an oxygen-free environment, and the pyrolysis environment of the embryo can be effectively ensured by filling with nitrogen.

[0049] Since the embryo contains chopped fibers, the chopped fibers will produce carbon, liquid oil and gas after heating and decomposition. It should be noted that since the embryo contains pore-forming agents, the embryo has a porous structure, and the liquid oil and gas produced after the chopped fibers are heated and decomposed can be discharged to the outside through the porous embryo, while the carbon produced after the chopped fibers are heated and decomposed will be retained inside the embryo.

[0050] See also Figure 4 According to some embodiments of the present application, optionally, step S110 specifically includes:

[0051] S111, adding ceramic powder, adhesive, and surfactant to silica sol to prepare a first slurry, and ball-milling the first slurry. Then adding a pore-forming agent, 5% of short-cut fibers, and water to the ball-milled first slurry to prepare a first mixed material 100, and ball-milling the first mixed material 100.

[0052] S112, adding ceramic powder, adhesive, and surfactant to the silica sol to prepare a second slurry, and ball-milling the second slurry. Then, adding a pore-forming agent, 10% of short-cut fibers, and water to the ball-milled second slurry to prepare a second mixed material 200, and ball-milling the second mixed material 200.

[0053] S113, adding ceramic powder, adhesive, and surfactant to the silica sol to prepare a third slurry, and ball-milling the third slurry. Then, adding a pore-forming agent, 15% of short-cut fibers, and water to the ball-milled third slurry to prepare a third mixed material 300, and ball-milling the third mixed material 300.

[0054] See also Figure 4 According to some embodiments of the present application, optionally, the amount of ceramic powder added to the first slurry is 30% to 35% of the mass of the silica sol. The amount of ceramic powder added to the second slurry is 25% to 30% of the mass of the silica sol. The amount of ceramic powder added to the third slurry is 20% to 25% of the mass of the silica sol.

[0055] The present application does not limit the amount of ceramic powder added. The amount of ceramic powder added to the first slurry can be selected between 30% and 35% of the mass of the silica sol, the amount of ceramic powder added to the second slurry can be selected between 25% and 30% of the mass of the silica sol, and the amount of ceramic powder added to the third slurry can be selected between 20% and 25% of the mass of the silica sol. Exemplarily, the amount of ceramic powder added to the first slurry is 30% of the mass of the silica sol. The amount of ceramic powder added to the second slurry is 25% of the mass of the silica sol. The amount of ceramic powder added to the third slurry is 20% of the mass of the silica sol.

[0056] See also Figure 4 According to some embodiments of the present application, optionally, the mass percentage of the adhesive is 1% to 2%, the mass percentage of the surfactant is 1% to 2%, and the mass percentage of the pore-forming agent is 2% to 3%.

[0057] The present application does not limit the mass percentage of the adhesive, the mass percentage of the surfactant, and the mass percentage of the pore-forming agent. The mass percentage of the adhesive can be selected between 1% and 2%, the mass percentage of the surfactant can be selected between 1% and 2%, and the mass percentage of the pore-forming agent can be selected between 2% and 3%. For example, the mass percentage of the adhesive is 1%, the mass percentage of the surfactant is 1%, and the mass percentage of the pore-forming agent is 2%.

[0058] See also Figure 4 According to some embodiments of the present application, optionally, the embryo body is kept warm in liquid nitrogen for 0.8h to 1.2h, and the temperature at which the embryo body is kept warm in liquid nitrogen is -40℃ to -45℃. The embryo body is pyrolyzed for 3h to 4h in a nitrogen atmosphere, and the temperature at which the embryo body is pyrolyzed in a nitrogen atmosphere is 400℃ to 800℃. The present application does not limit the time and temperature for the embryo body to be kept warm in liquid nitrogen, and the time and temperature for the embryo body to be pyrolyzed in a nitrogen atmosphere. Exemplarily, the embryo body is kept warm in liquid nitrogen for 0.8h, and the temperature at which the embryo body is kept warm in liquid nitrogen is -40℃. The embryo body is pyrolyzed for 3h in a nitrogen atmosphere, and the temperature at which the embryo body is pyrolyzed in a nitrogen atmosphere is 400℃.

[0059] See also Figure 4 According to some embodiments of the present application, optionally, the temperature at which the embryo is sintered is 1000°C to 1700°C, and the holding time for sintering the embryo is 2h to 5h. The present application does not limit the temperature at which the embryo is sintered and the holding time for sintering the embryo. Exemplarily, the temperature at which the embryo is sintered is 1000°C, and the holding time for sintering the embryo is 2h.

[0060] See also Figure 4According to some embodiments of the present application, optionally, the ceramic powder includes but is not limited to one or more of diatomaceous earth, aluminum oxide, zirconium oxide, silicon oxide, silicon carbide, silicon nitride, quartz sand, corundum sand, glass sand, kaolin, clay, and spray granulation.

[0061] In this embodiment, the ceramic powder is diatomaceous earth. The main component of diatomaceous earth is silicon dioxide (SiO2), and there are countless pores on the surface. It has the advantages of strong adsorption performance, light bulk density, uniform fineness, neutral pH value, non-toxicity, and good mixing uniformity.

[0062] In another embodiment, the ceramic powder is one or more of diatomaceous earth, aluminum oxide, zirconium oxide, silicon oxide, silicon carbide, silicon nitride, quartz sand, corundum sand, glass sand, kaolin, clay, and spray granulation. Exemplarily, the ceramic powder can be diatomaceous earth, aluminum oxide, and zirconium oxide.

[0063] See also Figure 4 According to some embodiments of the present application, optionally, the adhesive is polyvinyl butyral. The surfactant includes at least one of stearic acid and oleic acid. In this embodiment, the surfactant is stearic acid. In other embodiments, the surfactant can be stearic acid and oleic acid, and the surfactant can also be oleic acid.

[0064] In other feasible embodiments, the adhesive includes but is not limited to one or more of paraffin, beeswax, polyethylene, polyethylene wax, and polypropylene. For example, the adhesive is paraffin. Paraffin has high latent heat of phase change, almost no supercooling phenomenon, low vapor pressure when melted, is not easy to chemically react and has good chemical stability, has little change in phase change temperature and latent heat of phase change after multiple heat absorption and release, self-nucleation, no phase separation and corrosiveness.

[0065] See also Figure 4 According to some embodiments of the present application, optionally, the pore-forming agent includes but is not limited to one or more of polystyrene (PS), polymethyl methacrylate (PMMA), polyurethane (PU), polypropylene (PP), polyvinyl chloride (PVC), carbon powder, carbon powder, carbonate, nitrate, ammonium salt, sawdust, flour, corn flour, starch and soybean flour.

[0066] In this embodiment, the pore-forming agent is polymethyl methacrylate (PMMA). The mechanical strength of polymethyl methacrylate is relatively high: the relative molecular mass of polymethyl methacrylate is about 2 million, it is a long-chain high molecular polymer, and the chain forming the molecule is very soft, so the strength of polymethyl methacrylate is relatively high, and the tensile and impact resistance is 7 to 18 times higher than that of ordinary glass, and the melting point of polymethyl methacrylate is low. In the presence of oxygen, polymethyl methacrylate starts to burn at 458°C, and after burning, it generates carbon dioxide, water, carbon monoxide and some low molecular compounds including formaldehyde. In other embodiments, the pore-forming agent is polyvinyl chloride (PVC).

[0067] See also Figure 4 According to some embodiments of the present application, the chopped fibers may include one or more of organic cotton, kapok fibers, polyethylene foam (PE foam), polypropylene cotton (PP cotton), polyethylene terephthalate fiber (PET fiber), and polyamide fiber (PA). In this embodiment, the chopped fibers are kapok fibers.

[0068] See also Figure 1 , Figure 2 and Figure 3 According to some embodiments of the present application, optionally, the thickness of the third mixture 300, the second mixture 200 and the first mixture 100 in the mold 400 gradually increases. The number of micropores of the third mixture 300, the second mixture 200 and the first mixture 100 gradually decreases. The pores of the micropores of the third mixture 300, the second mixture 200 and the first mixture 100 gradually increase.

[0069] See also Figure 1 , Figure 2 and Figure 3 , one embodiment of the present invention further provides a porous ceramic heating element 20 including: a carbon fiber ceramic body 10 prepared by the preparation method of the carbon fiber ceramic body 10 and a heating net 500, the heating net 500 is arranged on the carbon fiber ceramic body 10, and is in contact with the third mixture 300. Specifically, the heating net 500 is connected to the carbon fiber ceramic body 10 through a porous ceramic glue. The carbon fiber ceramic body 10 is a multi-layer structure. It can be understood that the carbon fiber ceramic body 10 includes a first layer, an intermediate layer and a second layer arranged in a vertical direction, the first layer is a first mixture 100, the intermediate layer is a second mixture 200, and the second layer is a third mixture 300.

[0070] More specifically, the carbon fiber ceramic body 10 has a contact surface that contacts the heating net 500. In this embodiment, the contact surface is the lower surface of the carbon fiber ceramic body 10. That is, the contact surface is the lower surface of the third mixed material 300.

[0071] As the content of chopped fibers in the first mixture 100, the second mixture 200 and the third mixture 300 gradually increases, the thermal conductivity of the first mixture 100, the second mixture 200 and the third mixture 300 gradually increases, and the number of micropores in the third mixture 300, the second mixture 200 and the first mixture 100 gradually decreases; the pores of the micropores in the third mixture 300, the second mixture 200 and the first mixture 100 gradually increase. The third mixture 300 has more carbon fibers, more micropores and smaller micropores, which can conduct heat more conveniently, and the temperature of the third mixture 300 is higher, which can heat the atomized liquid more evenly. The amount of carbon fibers in the second mixture 200 and the first mixture 100 is less than that in the third mixture 300, and the number of micropores in the second mixture 200 and the first mixture 100 is less than that in the third mixture 300, and the pore size is larger, which can conduct excess heat, realize preheating of the atomized liquid, and better conduct the atomized liquid. By placing the heating net 500 in contact with the third mixed material 300 with high thermal conductivity, the heat distribution of the carbon fiber ceramic body 10 can be further ensured to be uniform, effectively avoiding the phenomenon of excessive local temperature. Example

[0072] The present disclosure is more specifically described in the following examples, which are intended for illustrative purposes only, since various modifications and variations within the scope of the present disclosure will be apparent to those skilled in the art. Example

[0073] S110, adding ceramic powder, 1% of adhesive, and 1% of surfactant to the silica sol to prepare a first slurry, and ball-milling the first slurry for 12 hours. Then, adding 2% of pore-forming agent, 5% of short-cut fibers and water to the first slurry after ball milling to prepare a first mixed material 100, and ball-milling the first mixed material 100 for 2 hours. Among them, the amount of ceramic powder added is 30% of the mass of the silica sol. Specifically, the ceramic powder is diatomaceous earth, the adhesive is polyvinyl butyral ester, the surfactant is stearic acid, and the short-cut fibers are kapok fibers.

[0074] Ceramic powder, 1% of adhesive, and 1% of surfactant are added to the silica sol to prepare a second slurry, and the second slurry is ball-milled for 12 hours. Then, 2% of pore-forming agent, 10% of short-cut fibers and water are added to the second slurry after ball milling to prepare a second mixed material 200, and the second mixed material 200 is ball-milled for 2 hours. Among them, the amount of ceramic powder added is 25% of the mass of the silica sol. Specifically, the ceramic powder is diatomaceous earth, the adhesive is polyvinyl butyral ester, the surfactant is stearic acid, and the short-cut fibers are kapok fibers.

[0075] Ceramic powder, 1% of adhesive, and 1% of surfactant were added to the silica sol to prepare a third slurry, and the third slurry was ball-milled for 12 hours. Then, 2% of pore-forming agent, 15% of short-cut fiber and water were added to the third slurry after ball milling to prepare a third mixed material 300, and the third mixed material 300 was ball-milled for 2 hours. Among them, the amount of ceramic powder added was 25% of the mass of the silica sol. Specifically, the ceramic powder was diatomaceous earth, the adhesive was polyvinyl butyral ester, the surfactant was stearic acid, and the short-cut fiber was kapok fiber.

[0076] S120, first pour the ball-milled third mixture 300 into the mold 400, then pour the ball-milled second mixture 200, and finally pour the ball-milled first mixture 100 to obtain a raw material slurry.

[0077] S130, the mold 400 filled with the raw material slurry is kept warm in liquid nitrogen at a temperature of -40°C for 1 hour, and then demolded to obtain an embryo body.

[0078] S140, pyrolyzing the embryo in a nitrogen atmosphere for 3 hours, the temperature of the embryo in the nitrogen atmosphere being 400° C., and sintering the pyrolyzed embryo at 1000° C. and keeping the temperature for 2 hours to produce a carbon fiber ceramic body 10. Example

[0079] The difference between this embodiment and embodiment 1 is that the amount of ceramic powder added to the first slurry is 35% of the mass of the silica sol. The amount of ceramic powder added to the second slurry is 30% of the mass of the silica sol. The amount of ceramic powder added to the third slurry is 25% of the mass of the silica sol. The mass percentage of the adhesive is 2%, the mass percentage of the surfactant is 2%, and the mass percentage of the pore-forming agent is 3%. Example

[0080] The difference between this embodiment and embodiment 1 is that the embryo body is kept warm in liquid nitrogen for 1.2 hours, and the temperature of the embryo body in liquid nitrogen is -45°C. The embryo body is pyrolyzed in a nitrogen atmosphere for 4 hours, and the temperature of the embryo body in a nitrogen atmosphere is 800°C. The embryo body is sintered at a temperature of 1700°C, and the sintering temperature is kept warm for 5 hours.

[0081] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0082] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a carbon fiber ceramic body, characterized in that: The following steps are involved: S110, adding ceramic powder, adhesive, and surfactant to silica sol to form slurry and performing ball milling to form a first slurry, a second slurry, and a third slurry, respectively adding 5%, 10%, and 15% of chopped fibers, a pore-forming agent, and water to the first slurry, the second slurry, and the third slurry, and performing ball milling to form a first mixture, a second mixture, and a third mixture; S120, pouring the third mixed material, the second mixed material, and the first mixed material into a mold in sequence to obtain a raw material slurry; S130, keeping the mold containing the raw material slurry warm in liquid nitrogen, and then demoulding to obtain an embryo body; S140, pyrolyzing the embryo in a nitrogen atmosphere, and sintering the pyrolyzed embryo to produce the carbon fiber ceramic body; Among them, the amount of the ceramic powder added to the first slurry is 30% to 35% of the mass of the silica sol; the amount of the ceramic powder added to the second slurry is 25% to 30% of the mass of the silica sol; the amount of the ceramic powder added to the third slurry is 20% to 25% of the mass of the silica sol.

2. The method for preparing a carbon fiber ceramic body according to claim 1, characterized in that: Step S110 specifically includes: The ceramic powder, the adhesive, and the surfactant are added to the silica sol to prepare a first slurry and ball-mill the slurry; then a pore former, 5% of chopped fibers, and water are added to the first slurry after ball milling to prepare a first mixture, and the first mixture is ball-milled; The ceramic powder, the adhesive, and the surfactant are added to the silica sol to prepare a second slurry, and the second slurry is ball-milled; then, the pore former, 10% of the chopped fibers, and the water are added to the second slurry after ball milling to prepare a second mixture, and the second mixture is ball-milled; The ceramic powder, the adhesive, and the surfactant are added to the silica sol to prepare a third slurry, and the third slurry is ball-milled; then, the pore-forming agent, 15% of the chopped fibers, and the water are added to the third slurry after ball milling to prepare a third mixture, and the third mixture is ball-milled.

3. The method for preparing a carbon fiber ceramic body according to claim 1, characterized in that: The mass percentage of the adhesive is 1% to 2%, the mass percentage of the surfactant is 1% to 2%, and the mass percentage of the pore-forming agent is 2% to 3%.

4. The method for preparing a carbon fiber ceramic body according to claim 1, characterized in that: The embryo is kept warm in liquid nitrogen for 0.8 h to 1.2 h, and the temperature at which the embryo is kept warm in liquid nitrogen is -40°C to -45°C; the embryo is pyrolyzed in a nitrogen atmosphere for 3 h to 4 h, and the temperature at which the embryo is pyrolyzed in a nitrogen atmosphere is 400°C to 800°C; the embryo is sintered at a temperature of 1000°C to 1700°C.

5. The method for preparing a carbon fiber ceramic body according to claim 1, characterized in that: The temperature for sintering the embryo is 1000° C. to 1700° C., and the insulation time for sintering the embryo is 2 h to 5 h.

6. The method for preparing a carbon fiber ceramic body according to claim 1, characterized in that: The thicknesses of the third mixture, the second mixture and the first mixture in the mold gradually increase.

7. The method for preparing a carbon fiber ceramic body according to claim 1, characterized in that: The number of micropores of the third mixture, the second mixture and the first mixture gradually decreases; the pores of the micropores of the third mixture, the second mixture and the first mixture gradually increase.

8. The method for preparing a carbon fiber ceramic body according to claim 1, characterized in that: The chopped fibers include one or more of organic cotton, polyethylene foam, polypropylene cotton, polyethylene terephthalate fiber, and polyamide fiber.

9. A porous ceramic heating element, characterized in that: include: The carbon fiber ceramic body prepared by the method for preparing a carbon fiber ceramic body as claimed in any one of claims 1 to 8; The heating net is arranged on the carbon fiber ceramic body and is in contact with the third mixed material.

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