Carbon ceramic vessel and preparation method thereof

Abstract

The invention provides a carbon ceramic vessel and a preparation method thereof.The preparation method of the carbon ceramic vessel comprises the steps that a ceramic body is subjected to first-time polishing treatment, and the polished ceramic body is obtained; carrying out sintering molding on the polished ceramic green body to obtain a sintered ceramic green body; carrying out liquid carburization and gas carburization on the sintered ceramic body to obtain a ceramic body of which at least part of pores contain a carbon film; and carrying out secondary polishing treatment on the ceramic green body containing the carbon film in at least part of pores to obtain the carbon ceramic vessel. According to the preparation method of the carbon ceramic vessel, through liquid carburization and gas carburization, a large number of carbon films can be formed in pores of the ceramic body, the water absorption rate of the ceramic body is greatly reduced, and the heat transfer performance is improved; and meanwhile, through two times of polishing treatment, the surface roughness and surface pores of the carbon ceramic ware can be reduced, and the carbon ceramic ware is glossy and better in appearance effect.

Description

Technical Field

[0001] This application relates to the field of kitchenware technology, and in particular to a carbon ceramic vessel and its preparation method. Background Technology

[0002] With the continuous advancement of technology, ceramic materials are increasingly widely used in daily life, especially in heat-resistant ceramic products such as cookware and tableware. However, the relatively poor thermal conductivity of traditional ceramic materials limits their application in areas of high-efficiency heat conduction. To address this issue, researchers are constantly exploring various methods to improve the thermal conductivity of ceramics, among which carburizing technology has attracted considerable attention. Carburizing technology involves introducing carbon elements into the surface or interior of ceramic materials through specific processes to improve their thermal conductivity. This technology mainly includes two methods: gas carburizing and liquid carburizing, both of which can effectively improve the thermal conductivity of ceramics. However, in practical applications, water absorption rate and surface glaze layer become key factors affecting the carburizing effect.

[0003] First, water absorption rate has a significant impact on carburizing effect. During carburizing, if the water absorption rate of the ceramic material is too low, the carburizing concentration will be too low, resulting in very limited improvement in thermal conductivity. Conversely, ceramic materials with moderate or high water absorption rates exhibit better carburizing effects and more significant improvements in thermal conductivity. However, excessive water absorption can also bring new problems, such as water seepage, which will seriously affect the user experience. Second, the surface glaze layer is also an important factor affecting carburizing effect. Everyday ceramics are usually covered with a glaze layer to improve the product's aesthetics, ease of cleaning, and durability. However, this glaze layer becomes a major obstacle during the carburizing process. Both high-temperature glazes and slurry glazes will adversely affect the carburizing effect. While unglazed treatment may result in better carburizing, the ceramic surface is prone to roughness, inability to conceal imperfections, and a lack of luster, severely impacting the product's aesthetics and practicality.

[0004] To address the aforementioned issues, how to achieve effective carburizing treatment and improve thermal conductivity while ensuring the aesthetics and practicality of ceramic materials has become an urgent problem to be solved. Currently, although some carburized ceramic products exist on the market, they still have many shortcomings in terms of water absorption and surface glaze treatment. To resolve this contradiction, researchers have begun to explore new carburizing processes and materials. For example, by adjusting the formulation and preparation process of ceramic materials, they aim to avoid water seepage while ensuring an appropriate water absorption rate. In addition, researchers are dedicated to developing new glaze materials to reduce obstacles to the carburizing effect while maintaining the aesthetics and ease of cleaning of the ceramic surface. However, despite some progress, current research has not yet completely resolved the contradiction between water absorption and surface glaze. Therefore, further research and innovation are urgently needed to develop high thermal conductivity ceramic materials that are both aesthetically pleasing and practical.

[0005] In summary, carburizing heat-resistant ceramics for daily use can significantly improve their thermal conductivity. However, water absorption and the surface glaze layer are key factors affecting the carburizing effect. To address these issues, further research and innovation are needed to develop ceramic materials that satisfy both aesthetic requirements and high thermal conductivity. This will provide broader application opportunities for ceramic products in the field of high-efficiency heat conduction, while also helping to improve the user experience. Summary of the Invention

[0006] In view of this, one objective of this application is to provide a method for preparing carbon ceramic ware, which can form a large amount of carbon film in the pores of the ceramic body by liquid carburizing and gas carburizing, thereby significantly reducing the water absorption rate of the ceramic body and improving the heat transfer performance; at the same time, by polishing twice, the surface roughness and surface porosity of the carbon ceramic ware can be reduced, making the carbon ceramic ware glossy and with a better appearance.

[0007] Another objective of this application is to provide a carbon ceramic vessel.

[0008] To achieve the above objectives, the first aspect of this application proposes a method for preparing carbon ceramic vessels, comprising:

[0009] The ceramic blank is first polished to obtain the polished ceramic blank.

[0010] The polished ceramic blank is sintered to obtain a sintered ceramic blank.

[0011] The sintered ceramic body is subjected to liquid carburizing and gas carburizing to obtain a ceramic body containing a carbon film in at least some of the pores.

[0012] The ceramic body containing a carbon film in at least some of its pores is subjected to a second polishing process to obtain the carbon ceramic vessel.

[0013] The method for preparing carbon ceramic ware described in this application, through liquid carburizing and gas carburizing, can form a large number of carbon films within the pores of the ceramic body, creating highly thermally conductive channels and significantly improving thermal conductivity. Simultaneously, because a large number of carbon films are formed within the pores of the ceramic body, the internal pores are occupied by the carbon films, reducing the water absorption rate of the ceramic body to below 3.5 wt%. After a water seepage test, there was no significant water seepage after 24 hours, and there is less likelihood of residual odors or other abnormalities during cooking. Furthermore, through two polishing processes, the surface roughness (Ra≤1%) and surface porosity of the carbon ceramic ware can be reduced, giving it a glossy finish and a better appearance.

[0014] In some embodiments, the surface roughness of the ceramic body after the first polishing treatment is a μm, and the surface roughness of the carbon ceramic vessel after the second polishing treatment is b μm, where b is less than a. In this application, the purpose of performing the first polishing treatment on the ceramic body is to initially reduce the surface roughness of the relatively soft, unsintered ceramic body and reduce texture, so that a relatively smooth surface can be obtained after subsequent sintering.

[0015] In some embodiments, 'a' satisfies: 2 ≤ a ≤ 4. In this application, controlling the surface roughness of the ceramic body after the first polishing treatment to be 2-4 μm achieves a bright, easy-to-clean surface and a uniform appearance. If the roughness is less than 2 μm, fine polishing is required during the polishing process, significantly increasing process costs and reducing production efficiency. Furthermore, fine polishing can clog ceramic pores, hindering the subsequent infiltration of carbon materials during the body's hollow state. If the roughness is greater than 4 μm, the surface is relatively rough, resulting in a larger carbon film deposited on the surface after carburizing, and subsequent surface polishing becomes more difficult due to the roughness. In some embodiments, 'b' satisfies: b ≤ 1. In this application, controlling the surface roughness of the carbon ceramic ware after the second polishing treatment to be lower than Ra 1μm can improve the ease of cleaning for consumers during use (rough surfaces are prone to food sticking and are difficult to clean); at the same time, the second polishing treatment is a fine polishing, which also seals the larger pores on the surface, making it difficult for food to penetrate into the pores and avoiding the problem of cross-contamination of flavors; in addition, controlling the surface roughness of the carbon ceramic ware after the second polishing treatment to be lower than Ra 1μm can make the carbon ceramic ware glossy and have a better appearance.

[0016] In some embodiments, the first polishing process includes at least one of mechanical polishing and manual polishing. In some embodiments, the second polishing process includes at least one of abrasive polishing and mechanical polishing.

[0017] In some embodiments, the sintered ceramic body is first subjected to liquid carburizing, followed by gas carburizing, to obtain a ceramic body containing a carbon film in at least some of its pores. In this application, the method of liquid carburizing followed by gas carburizing achieves better technical effects than the method of gas carburizing followed by liquid carburizing, such as a higher pore filling rate of the carbon film, lower water absorption, and better thermal conductivity. This is because liquid carburizing followed by gas carburizing results in a larger amount of carbon deposited, while gas carburizing followed by liquid carburizing leads to larger pores after carburizing, since liquid carburizing generally forms a larger carbon film, while gas carburizing can deposit carbon in smaller pores, creating a sealing effect. Therefore, in the method for preparing carbon ceramic vessels according to the embodiments of this application, it is preferable to first perform liquid carburizing on the sintered ceramic body and then gas carburizing.

[0018] In some embodiments, the liquid carburizing includes:

[0019] The sintered ceramic body or the gas carburized ceramic body is repeatedly impregnated with a first carbon source solution, and a first drying treatment is performed after each impregnation treatment to obtain an impregnated ceramic body.

[0020] The impregnated ceramic blank is carbonized in a vacuum or a first reducing gas atmosphere to obtain a liquid carburized ceramic blank.

[0021] In this application, through impregnation treatment, the liquid carbon source (first carbon source solution) can penetrate into the pores of the ceramic body via capillary action. Furthermore, testing has shown that liquid carburization can form a carbon film within the larger pores (pore diameter greater than 10 μm) of the ceramic body, and reduces water absorption by 2 / 3.

[0022] In some embodiments, the first carbon source solution includes at least one of a phenolic resin solution and a sucrose solution. Since phenolic resin and sucrose have good carbonization properties, and their solutions can effectively wet and penetrate ceramics, they can be selected as suitable liquid carburizing carbon sources.

[0023] In some embodiments, the solid content in the first carbon source solution is 5-20 wt%. Taking sucrose solution as an example, sucrose has a relatively small molecular size, and at a concentration limited to 5-20%, its viscosity is also low, making it easier to penetrate into the pores of ceramics with a diameter of 10 μm or more.

[0024] In some embodiments, the duration of each impregnation treatment is 1-4 hours. In this application, the duration of each impregnation treatment is within the above range to ensure the maximum amount of the first carbon source penetrating; if it is less than 1 hour, the amount of the first carbon source penetrating is insufficient; if it is more than 4 hours, the increase in the amount of the first carbon source penetrating is not significant, the working time increases, the cost increases, and the cost-effectiveness decreases.

[0025] In some embodiments, the impregnation treatment is performed 2-5 times. In this application, selecting 2-5 times for the impregnation treatment allows the first carbon source to reach its maximum concentration in the liquid carburizing process; beyond 5 times, the amount of the first carbon source in the liquid carburizing process changes less.

[0026] In some embodiments, the carbonization treatment temperature is 800-1200℃, and the carbonization treatment time is 2-5 hours. In this application, the carbonization temperature and time are within the above-mentioned ranges, which can achieve a better carbonization effect.

[0027] In some embodiments, the gas carburizing includes:

[0028] The ceramic preform after liquid phase carburization or the sintered ceramic preform is subjected to chemical vapor infiltration.

[0029] In this application, gas carburizing can penetrate into micron-sized pores, such as 10 μm pores, or even smaller pores. Simultaneously, if liquid carburizing is performed first, followed by gas carburizing, the gas carburizing can also penetrate into the pores remaining from the liquid carburizing process.

[0030] In some embodiments, the second carbon source for chemical vapor permeation includes at least one of alkanes, alkenes, alkyl acids, and small molecule alcohols. In this application, selecting the above-mentioned substances as the second carbon source for chemical vapor permeation can achieve a higher carburization ratio.

[0031] In some embodiments, the chemical vapor infiltration is carried out under a protective gas atmosphere, the volume of which is mL and the volume of the second carbon source after vaporization is n L, wherein m and n satisfy: 5% ≤ n / (m+n) ≤ 10%. In this application, the total volume of the protective gas and the second carbon source after vaporization is within the above range, which can achieve a higher carburization ratio.

[0032] In some embodiments, the temperature of the chemical vapor infiltration is 700-900°C, and the time of the chemical vapor infiltration is 5-12 hours. In this application, the chemical vapor infiltration process is also the process of heat-treating the ceramic body after liquid carburization or the sintered ceramic body using a second carbon source. Taking the case of liquid carburization followed by gas carburization as an example, by controlling the carburization time and carbon source concentration of the second carbon source, the carburization ratio is determined to be between 10-30% (i.e., after liquid carburization and gas carburization, the carbon content in the ceramic body is 10-30 wt%). If the carburization concentration is low, the thermal conductivity will not be improved significantly. If the carburization ratio is too high, more carbides will be formed in the matrix. The presence of carbides at high temperatures will affect the thermal shock performance of the matrix material. In addition, the higher the carburization ratio, the higher the cost of electricity, gas, and labor.

[0033] In some embodiments, the ceramic body comprises at least one of red clay ceramic, kaolin ceramic, and cordierite ceramic, and the sintering temperatures of the red clay ceramic, kaolin ceramic, and cordierite ceramic are 1100-1200℃, 1300-1400℃, and 1200-1300℃, respectively. In the embodiments of this application, selecting ceramics of the above-mentioned materials and sintering them at the above-mentioned temperatures can ensure that the ceramic body has suitable water absorption and strength, etc., so that the ceramic body has a good carburizing effect, and the final carbonized ceramic ware has excellent mechanical strength.

[0034] In some embodiments, the method for preparing the carbon ceramic vessel further includes the steps of ball milling, dehydration and drying, kneading and spinning into shape, and second drying to obtain the ceramic blank.

[0035] In some embodiments, the ceramic blank has a receiving cavity.

[0036] In some embodiments, the carbon ceramic vessel is a cooking utensil.

[0037] The second aspect of this application provides a carbon ceramic vessel, prepared using the carbon ceramic vessel preparation method described in this application; the carbon ceramic vessel includes the sintered ceramic body and the carbon film; the carbon film is disposed within at least a portion of the pores of the sintered ceramic body.

[0038] In some embodiments, the carbon content of the carbon ceramic vessel is 10-30% by weight. In this application, the carbon content of the carbon ceramic vessel is within the above range, which can achieve better thermal conductivity.

[0039] In some embodiments, the water absorption rate of the carbon ceramic utensil is below 3.5 wt%. In this application, the water absorption rate of the carbon ceramic utensil is within the above range, which can solve the problems of water seepage and flavor transfer during the cooking process.

[0040] In some embodiments, the thermal conductivity of the carbon ceramic cookware is 2-10 W / (m·K). In this application, the thermal conductivity of the carbon ceramic cookware is within the above range, which improves the thermal conductivity of the ceramic cookware and increases cooking efficiency.

[0041] In some embodiments, the surface roughness of the carbon ceramic utensil is below 1 μm. In this application, the surface roughness of the carbon ceramic utensil below 1 μm improves the ease of cleaning for consumers during use (rough surfaces easily attract food and are difficult to clean); simultaneously, it prevents food from easily penetrating the pores, avoiding the problem of flavor transfer. Furthermore, it gives the carbon ceramic utensil a glossy finish, resulting in a better appearance.

[0042] The method for preparing carbon ceramic vessels described in this application can bring at least the following beneficial effects:

[0043] 1. Through liquid carburizing and gas carburizing, a large number of carbon films can be formed in the pores of the ceramic body, creating highly thermally conductive channels and significantly improving thermal conductivity. Simultaneously, because a large number of carbon films are formed within the ceramic body, the internal pores are occupied by the carbon film, reducing the water absorption rate of the ceramic body to below 3.5wt%. After a water seepage test, there was no significant water seepage after 24 hours, and there is less likelihood of residual odors or other abnormalities during cooking.

[0044] 2. Through two polishing processes, the surface roughness (Ra≤1%) and surface porosity of carbon ceramic vessels can be reduced, giving them a glossy finish and a better appearance.

[0045] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0046] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings.

[0047] in:

[0048] Figure 1 This is a flowchart illustrating a method for preparing a carbon ceramic vessel, as shown in an exemplary embodiment of this application.

[0049] Figure 2 A flowchart illustrating a method for preparing a carbon ceramic vessel, as shown in another exemplary embodiment of this application.

[0050] Figure 3 This is a schematic diagram of the structure of a carbon ceramic vessel, illustrating an exemplary embodiment of this application.

[0051] Figure 4 This is a schematic diagram of the structure of the ceramic body wall after sintering in a carbon ceramic vessel, as shown in an exemplary embodiment of this application.

[0052] Figure 5 The image shows a scanning electron microscope (SEM) image of the carbon ceramic vessel prepared in Example 1.

[0053] Figure label:

[0054] 1-Sintered ceramic body; 101-Pore; 1011-First pore; 1012-Second pore; 2-Carbon film; 201-First carbon film; 202-Second carbon film. Detailed Implementation

[0055] The embodiments of this application are described in detail below, with examples of these embodiments illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0056] In this application, the disclosure of numerical ranges includes all values ​​throughout the range and the disclosure of further subdivisions of the range, including the endpoints and subranges given for these ranges.

[0057] Unless otherwise specified, all raw materials and equipment involved in this application are self-made through commercial means or known methods; and all methods involved are conventional methods unless otherwise specified.

[0058] The following description, with reference to the accompanying drawings, describes a method for preparing a carbon ceramic vessel and the carbon ceramic vessel itself, according to embodiments of this application.

[0059] <Preparation Method of Carbon Ceramic Vessels>

[0060] Figure 1 This is a flowchart illustrating a method for preparing carbon ceramic vessel according to an exemplary embodiment of this application. The inventive concept of this method is as follows: a carbon film is formed in at least a portion of the pores of the ceramic body through liquid carburizing and gas carburizing—liquid carburizing mainly forms a carbon film in pores with a diameter of 10 μm or larger, while gas carburizing forms a carbon film in pores with a diameter of less than 10 μm. This improves the overall thermal conductivity of the ceramic body. Simultaneously, because the carbon film fills most of the pores inside the ceramic body, the water absorption rate of the ceramic body is reduced (below 3.5 wt%). Furthermore, replacing the traditional glaze layer with a first polishing treatment before sintering and a second polishing treatment after carburizing reduces the surface roughness of the product (Ra ≤ 1%), ensuring a glossy surface and excellent appearance.

[0061] like Figure 1 As shown, the preparation method of this carbon ceramic vessel includes the following steps:

[0062] S101. The ceramic blank is polished for the first time to obtain the polished ceramic blank.

[0063] In some embodiments, the ceramic blank has a receiving cavity.

[0064] In some implementations, the ceramic body is a ceramic body for kitchen utensils, such as a ceramic body for cooking utensils, a ceramic body for tableware, etc.

[0065] For example, the ceramic body of a cooking utensil includes, but is not limited to, the body of a ceramic pot or the body of a ceramic inner pot.

[0066] In some embodiments, the ceramic body is made of at least one of the following: red clay ceramics, kaolin ceramics, cordierite ceramics, etc.

[0067] In some implementations, such as Figure 2 As shown, the preparation method of carbon ceramic vessels also includes the steps of ball milling, dehydration and drying, kneading and spinning into shape, and second drying to obtain the above-mentioned ceramic blank (that is, the step of preparing the ceramic blank).

[0068] In some embodiments, the first polishing process includes, but is not limited to, at least one of mechanical polishing, manual polishing, etc.

[0069] As an alternative example, the first polishing process is mechanical polishing.

[0070] In some implementations, the surface roughness (Ra) of the polished ceramic blank is a μm, where a satisfies: 2 ≤ a ≤ 4.

[0071] In the embodiments of this application, the surface roughness of the polished ceramic body is also the surface roughness of the ceramic body after the first polishing treatment. The purpose of the first polishing treatment of the ceramic body is to initially reduce the roughness of the relatively soft, unsintered ceramic body surface and reduce texture, so that a relatively smooth surface can be obtained after subsequent sintering. It should be emphasized that the first polishing treatment in this application is only to remove burrs, textures, etc., from the surface of the relatively soft, unsintered ceramic body, and does not involve any change in the internal pore structure of the ceramic body. Therefore, it has virtually no impact on subsequent liquid carburizing and gas carburizing. Furthermore, the roughness formed by the first polishing treatment has a slight impact on the surface porosity of the ceramic body. Generally, the greater the surface roughness of the ceramic body after the first polishing treatment, under the same conditions (carburizing, etc. remain unchanged), the greater the surface roughness and the lower the carbon content of the final carbon ceramic vessel; conversely, the smaller the surface roughness of the ceramic body after the first polishing treatment, under the same conditions (carburizing, etc. remain unchanged), the smaller the surface roughness and the higher the carbon content of the final carbon ceramic vessel.

[0072] By way of non-limiting example, the surface roughness of the polished ceramic body includes, but is not limited to, 2μm, 2.5μm, 3μm, 3.5μm or 4μm.

[0073] In the embodiments of this application, the surface roughness of the polished ceramic body is controlled to be 2-4 μm, which can achieve the effect of bright and easy-to-clean surface and uniform appearance. If it is less than 2 μm, fine polishing is required during the polishing process, which greatly increases the process cost and reduces the production efficiency. In addition, the fine polishing process will also cause the ceramic pores to be blocked, which will hinder the subsequent infiltration of carbon materials in the body. If it is greater than 4 μm, the surface is relatively rough, and a lot of carbon film will be deposited on the surface after carburizing. Furthermore, due to the relatively rough surface, subsequent surface polishing is more difficult.

[0074] S102. The polished ceramic blank obtained in step S101 is sintered to form a sintered ceramic blank.

[0075] In the embodiments of this application, sintering is carried out according to the sintering temperature of different ceramic systems.

[0076] In some embodiments, when the ceramic of the ceramic blank in step S101 is red clay ceramic, the sintering temperature of the polished ceramic blank obtained in step S101 is 1100-1200℃, including but not limited to 1100℃, 1125℃, 1150℃, 1175℃ or 1200℃; the sintering time is 8-15h, including but not limited to 8h, 10h, 12h or 14h.

[0077] In some embodiments, when the ceramic of the ceramic blank in step S101 is kaolin ceramic, the sintering temperature of the polished ceramic blank obtained in step S101 is 1300-1400℃, including but not limited to 1300℃, 1325℃, 1350℃, 1375℃ or 1400℃; the sintering time is 8-20h, including but not limited to 8h, 10h, 12h, 14h, 16h or 18h.

[0078] In some embodiments, when the ceramic of the ceramic blank in step S101 is cordierite ceramic, the sintering temperature of the polished ceramic blank obtained in step S101 is 1200-1300℃, including but not limited to 1200℃, 1225℃, 1250℃, 1275℃ or 1300℃; the sintering time is 8-18h, including but not limited to 8h, 10h, 12h, 14h, 16h or 18h.

[0079] S103. The sintered ceramic body obtained in step S102 is subjected to liquid carburizing and gas carburizing in sequence to obtain a ceramic body containing a carbon film in at least some of the pores.

[0080] The inventors discovered that infiltrating more carbon film into ceramics can significantly improve their thermal conductivity. However, the larger the ceramic pores, the higher its water absorption rate and the easier it is for water to seep in. Conventional carburizing treatment can only reduce the water absorption rate by 1-2%, creating a technical contradiction. The inventors then discovered that a co-carburizing treatment technique using liquid carburizing and gas co-carburizing can perfectly solve the above problem. Specifically, the liquid carburizing process penetrates into the pores of the sintered ceramic body with a pore size of 10μm or larger, while the gas carburizing process penetrates into the smaller pores (pore size less than 10μm) of the sintered ceramic body, further filling the ceramic pores and reducing the water absorption rate.

[0081] In some embodiments, liquid carburizing includes the following steps:

[0082] (1) The sintered ceramic blank is impregnated multiple times with a first carbon source solution, and a first drying treatment is performed after each impregnation treatment to obtain the impregnated ceramic blank.

[0083] (2) The impregnated ceramic blank is carbonized in a vacuum or a first reducing gas atmosphere to obtain a liquid carburized ceramic blank.

[0084] It should be noted that the above liquid carburizing method is suitable for continuous production, in which case the ceramic body after normal sintering is free of grease and moisture. In other cases, during non-continuous production, contamination such as grease and water may occur during transportation and storage. In such cases, a pretreatment step for the sintered ceramic body needs to be added before step (1) above (e.g., Figure 2 (As shown), to remove grease and moisture from the sintered ceramic body.

[0085] In some embodiments, the first carbon source solution includes, but is not limited to, at least one of phenolic resin solution, sucrose solution, etc. Since phenolic resin and sucrose have good carbonization properties, and their solutions can also effectively wet and penetrate ceramics, they can be selected as suitable carbon sources.

[0086] In some embodiments, the solid content in the first carbon source solution is 5-20 wt%, including but not limited to 5 wt%, 7.5 wt%, 10 wt%, 12.5 wt%, 15 wt%, 17.5 wt%, or 20 wt%. Taking sucrose solution as an example, sucrose has a relatively small molecular size, and at a concentration limited to 5-20%, its viscosity is also low, making it easier to penetrate into the pores of ceramics with a diameter of 10 μm or more.

[0087] As an alternative example, the first carbon source solution is a phenolic resin solution, wherein the solvent includes at least one of ethanol, methanol, etc.

[0088] As another alternative example, the first carbon source solution is a sucrose solution, wherein the solvent is water.

[0089] It should be noted that, in the embodiments of this application, the first carbon source solution is preferably a sucrose solution.

[0090] For example, the preparation method of the first carbon source solution includes: thoroughly stirring the first carbon source and solvent to make the material completely dissolved, thereby forming the first carbon source solution.

[0091] In some embodiments, the above impregnation treatment is to impregnate a sintered ceramic blank pretreated with a first carbon source solution.

[0092] In other embodiments, the above-mentioned impregnation process involves completely immersing the pretreated sintered ceramic blank in a first carbon source solution.

[0093] In some implementations, the duration of each immersion treatment is 1-4 hours, including but not limited to 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, or 4 hours.

[0094] It should be noted that the soaking time can be the same or different for each treatment.

[0095] In some implementations, the immersion treatment is performed at room temperature.

[0096] In the embodiments of this application, room temperature refers to 20-30°C.

[0097] In some implementations, the immersion treatment is performed 2 to 5 times, including but not limited to 2, 3, 4 or 5 times.

[0098] As an alternative example, the immersion treatment is performed 2-3 times.

[0099] In the embodiments of this application, through impregnation treatment, the liquid carbon source (first carbon source solution) can penetrate into the pores of the ceramic body through capillary action.

[0100] In some implementations, the first drying method includes, but is not limited to, oven drying, air drying, spray drying, etc.

[0101] In some embodiments, the carbonization temperature is 800-1200°C, including but not limited to 800°C, 850°C, 900°C, 950°C, 1000°C, 1050°C, 1100°C, 1150°C, or 1200°C.

[0102] In some embodiments, the carbonization treatment time is 2-5 hours, including but not limited to 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours or 5 hours.

[0103] In some implementations, the carbonization process is carried out in equipment such as high-temperature sintering furnaces and tubular furnaces.

[0104] In some embodiments, the first reducing gas includes, but is not limited to, at least one of hydrogen, methane, and carbon monoxide.

[0105] In some embodiments, liquid carburizing also includes a step of cooling the carbonized product.

[0106] In the embodiments of this application, it was found that by liquid carburizing, a carbon film can be formed in the larger pores (pore diameter greater than 10 μm) inside the ceramic, and the water absorption rate is reduced by 2 / 3.

[0107] In some embodiments, gas carburizing includes: subjecting the liquid-phase carburized ceramic preform to chemical vapor infiltration (CVI) to obtain a ceramic preform containing a carbon film in at least some of the pores.

[0108] In the embodiments of this application, the ceramic product that has undergone liquid carburization is placed at a high temperature for high-temperature carburization, forming a chemical vapor phase carburizing film. This process allows for the penetration of micron-sized pores that liquid carburization cannot reach, as well as pores formed during the liquid carburization process. Through gas permeation, pores up to 10 μm in size and pores remaining after liquid carburization can be penetrated.

[0109] In some embodiments, the second carbon source for chemical vapor permeation includes, but is not limited to, at least one of alkanes, alkenes, alkyl acids, and small molecule alcohols.

[0110] As an alternative example, the second carbon source for chemical vapor infiltration includes at least one of C1-5 alkanes, C2-5 alkenes, C2-5 alkyl acids, small molecule alcohols, etc.

[0111] By way of non-limiting example, the second carbon source in chemical vapor permeation includes, but is not limited to, at least one of methane (CH4), ethane (C2H6), and propane (C3H8); alkenes including but not limited to at least one of ethylene (C2H4) and propylene (C3H6); alkyl acids including but not limited to at least one of acetic acid (CH3COOH) and propionic acid (C2H5COOH); and small molecule alcohols including but not limited to at least one of methanol and ethanol.

[0112] In some embodiments, the temperature of chemical vapor permeation is 700-900°C, including but not limited to 700°C, 750°C, 800°C, 850°C or 900°C.

[0113] In some embodiments, the chemical vapor infiltration time is 5-12 hours, including but not limited to 5 hours, 6 hours, 7 hours, 8 hours, 10 hours, 11 hours, or 12 hours.

[0114] In the embodiments of this application, the chemical vapor infiltration process is also the process of heat-treating the ceramic body after liquid-phase carburization using a second carbon source. By controlling the carburizing time and carbon source concentration of the second carbon source, the carburizing ratio is determined to be between 10-30% (i.e., after liquid carburizing and gas carburizing, the carbon content in the ceramic body is 10-30 wt%). If the carburizing concentration is low, the thermal conductivity will not be significantly improved. If the carburizing ratio is too high, more carbides will be formed in the matrix. The presence of carbides at high temperatures will affect the thermal shock performance of the matrix material. In addition, the higher the carburizing ratio, the higher the cost of electricity, gas, and labor.

[0115] In some implementations, chemical vapor permeation is carried out under a protective gas atmosphere.

[0116] By way of non-limiting example, the protective gas includes, but is not limited to, at least one of inert gases and second reducing gases.

[0117] For example, inert gases include, but are not limited to, at least one of N2, Ar, He, etc.

[0118] For example, the second reducing gas includes, but is not limited to, at least one of H2, CO, etc.

[0119] In the embodiments of this application, atmospheric carbon is formed by the thermal decomposition of a second carbon source at high temperature (700-900℃), and the atmospheric carbon permeates into the ceramic pores in the environment.

[0120] In some embodiments, the volume of the protective gas is mL, and the volume of the second carbon source after gasification is n L, where m and n satisfy: 5% ≤ n / (m+n) ≤ 10%.

[0121] It should be noted that the above n / (m+n) is also the concentration of the second carbon source atmosphere.

[0122] As a non-restrictive enumeration, the values ​​of n / (m+n) include, but are not limited to, 5%, 6%, 7%, 8%, 9%, or 10%.

[0123] As an alternative example, the volume of the carbon ceramic vessel is 4L, and the total volume of the protective gas and the second carbon source after gasification, m+n, is 10L.

[0124] In some embodiments, the above-described chemical vapor infiltration process is carried out in a heat treatment atmosphere furnace.

[0125] S104. A second polishing process is performed on a ceramic body containing a carbon film in at least some of its pores to obtain a carbon ceramic vessel.

[0126] In some embodiments, the surface roughness (Ra) of the carbon ceramic vessel is b μm, where b is less than a (that is, the surface roughness of the ceramic body after the first polishing treatment mentioned above).

[0127] In the embodiments of this application, the surface roughness of the carbon ceramic vessel is also the surface roughness of the ceramic body containing a carbon film in at least some of the pores after the second polishing treatment.

[0128] In some implementations, b satisfies: b≦1.

[0129] By way of non-limiting example, the surface roughness of carbon ceramic vessels includes, but is not limited to, 1 μm, 0.9 μm, 0.8 μm, 0.7 μm, 0.6 μm, 0.5 μm, 0.4 μm, 0.3 μm, 0.2 μm, 0.1 μm or 0 μm.

[0130] In some embodiments, the second polishing process includes, but is not limited to, at least one of abrasive polishing, mechanical polishing, etc.

[0131] As an alternative example, the second polishing process is abrasive polishing (i.e., polishing with abrasive).

[0132] For example, the abrasives used in abrasive polishing include, but are not limited to, at least one of silicon carbide, silicon nitride, etc.

[0133] In the embodiments of this application, when the second polishing process is abrasive polishing, existing dedicated polishing fixtures can be used. For example, a supporting rotating fixture is placed inside a ceramic blank containing a carbon film in at least some of its pores, and polishing is performed manually or by a robotic arm.

[0134] In some embodiments, the method for preparing carbon ceramic vessels according to this application further includes a step of grinding the bottom of the product after the second polishing treatment.

[0135] In some implementations, the carbon ceramic vessels are kitchen utensils, including but not limited to cooking utensils and tableware.

[0136] For example, cooking utensils include, but are not limited to, ceramic inner pots, ceramic cookware, etc.

[0137] It should be noted that the method for preparing the carbon ceramic vessel in this application is not limited to the above-described method. Figure 1 The preparation process is shown. In some cases, the order of liquid carburizing and gas carburizing in step S103 can be reversed. That is, in step S103, the sintered ceramic body is first gas carburized, and then the gas-carburized ceramic body is liquid carburized. Similarly, depending on the specific situation, when production is not continuous, human-caused contamination such as grease and water may occur during transportation and storage. In this case, it is also necessary to add a pretreatment step for the sintered ceramic body before gas carburizing to remove the grease and moisture on the sintered ceramic body.

[0138] Furthermore, it should be emphasized that, as mentioned above, although the order of liquid carburizing and gas carburizing is not limited in the embodiments of this application, the case of liquid carburizing followed by gas carburizing can achieve better technical effects than the case of gas carburizing followed by liquid carburizing. For example, the carbon film filling rate of the pores is higher, the water absorption rate is lower, and the thermal conductivity is better. This is because liquid carburizing followed by gas carburizing results in a larger amount of carbon deposited. If gas carburizing is performed first, followed by liquid carburizing, the pores will be larger after carburizing, because liquid carburizing generally forms a larger carbon film, while gas carburizing can deposit in areas with smaller pore sizes, forming a sealing effect. Therefore, in the method for preparing carbon ceramic vessels in the embodiments of this application, it is preferable to perform liquid carburizing followed by gas carburizing on the sintered ceramic body first.

[0139] The method for preparing the carbon ceramic vessel according to the embodiments of this application can bring at least the following beneficial effects:

[0140] 1. Through liquid carburizing and gas carburizing, a large number of carbon films can be formed in the pores of the ceramic body, creating highly thermally conductive channels and significantly improving thermal conductivity. Simultaneously, because a large number of carbon films are formed in the pores of the ceramic body, the internal pores are occupied by the carbon film, reducing the water absorption rate of the ceramic body to below 3.5wt%. After a water seepage test, there was no significant water seepage after 24 hours, and there is less likelihood of residual odors or other abnormalities during cooking.

[0141] 2. Through two polishing processes, the surface roughness (Ra≤1%) and surface porosity of carbon ceramic vessels can be reduced, giving them a glossy finish and a better appearance.

[0142] <Carbon ceramic dishes>

[0143] The carbon ceramic vessel of this application embodiment is prepared using the carbon ceramic vessel preparation method of this application embodiment.

[0144] like Figure 3 and Figure 4 As shown, the carbon ceramic vessel includes a sintered ceramic body 1 and a carbon film 2; the carbon film 2 is disposed within at least a portion of the pores 101 of the sintered ceramic body 1.

[0145] In some embodiments, the pore 101 includes a first pore 1011 and a second pore 1012, wherein the diameter of the first pore 1011 is larger than the diameter of the second pore 1012.

[0146] In some embodiments, the diameter of the first pore 1011 is greater than 10 μm, and the diameter of the second pore 1012 is less than 10 μm.

[0147] In some embodiments, the carbon film 2 includes a first carbon film 201 and a second carbon film 202. The first carbon film 201 is disposed in the first pore 1011 and is formed by liquid carburizing in the above-described method for preparing carbon ceramic vessels. The second carbon film 202 is disposed in the second pore 202 and is formed by gas carburizing in the above-described method for preparing carbon ceramic vessels.

[0148] In some embodiments, the carbon content of the carbon ceramic vessel is 10-30% by weight.

[0149] For example, the carbon content of carbon ceramic vessels, by weight percentage, includes but is not limited to 10%, 12.5%, 15%, 17.5%, 20%, 22.5%, 25%, 27.5%, or 30%.

[0150] It should be noted that, as can be seen from the aforementioned preparation method, the sole source of carbon content in the carbon ceramic vessel is the first carbon source solution during liquid carburizing and the second carbon source during chemical vapor deposition (i.e., gas carburizing). Therefore, carbon content can be used to indirectly characterize the carbon film content in the carbon ceramic vessel of this application embodiment, and carbon content is positively correlated with carbon film content. A higher carbon content indicates a higher proportion of carbon film in the pores of the sintered ceramic body. For the same ceramic material, a higher proportion of carbon film in the pores of the sintered ceramic body results in a higher pore-filling ratio, lower water absorption rate, and better thermal conductivity in the carbon ceramic vessel.

[0151] It should also be noted that the carbon content of the carbon ceramic vessel used in this application can be obtained by testing with energy dispersive X-ray spectroscopy (EDS) or similar instruments.

[0152] In some embodiments, the water absorption rate of the carbon ceramic vessel is below 3.5 wt%, including but not limited to 3.5 wt%, 3 wt%, 2.5 wt%, 2 wt%, 1.5 wt%, 0.9 wt%, 0.8 wt%, 0.7 wt%, 0.6 wt%, 0.5 wt%, 0.4 wt%, 0.3 wt%, 0.2 wt%, or 0.1 wt%.

[0153] As a preferred example, the water absorption rate of carbon ceramic vessels is less than 1 wt%.

[0154] In some embodiments, the thermal conductivity of the carbon ceramic vessel is 2-10 W / (m·K), including but not limited to 2 W / (m·K), 4 W / (m·K), 5 W / (m·K), 6 W / (m·K), 8 W / (m·K) or 10 W / (m·K).

[0155] In some embodiments, the surface roughness of the carbon ceramic vessel is less than 1 μm, including but not limited to 1 μm, 0.9 μm, 0.8 μm, 0.7 μm, 0.6 μm, 0.5 μm, 0.4 μm, 0.3 μm or 0.1 μm.

[0156] In some embodiments, the sintered ceramic blank 1 has a receiving cavity 3.

[0157] It should be noted that the surface of the carbon ceramic vessel in this embodiment of the application is unglazed.

[0158] The carbon ceramic vessel of this application embodiment has at least the beneficial effects of the preparation method of the carbon ceramic vessel of this application embodiment.

[0159] The following non-limiting embodiments further illustrate certain features of the present technology.

[0160] [Examples and Comparative Examples]

[0161] Example 1

[0162] <Carbon ceramic dishes>

[0163] like Figure 3 and Figure 4 As shown, the carbon ceramic vessel in this embodiment is a 4L ceramic pot, comprising a sintered ceramic body 1 and a carbon film 2. The sintered ceramic body 1 has a receiving cavity 3; the carbon film 2 is disposed within at least a portion of the pores 101 of the sintered ceramic body 1.

[0164] Pore ​​101 includes a first pore 1011 and a second pore 1012. The pore diameter of the first pore 1011 is larger than that of the second pore 1012. The pore diameter of the first pore 1011 is greater than 10 μm, and the pore diameter of the second pore 1012 is less than 10 μm. Carbon film 2 includes a first carbon film 201 and a second carbon film 202. The first carbon film 201 is disposed in the first pore 1011 and is a carbon film formed by liquid carburizing. The second carbon film 202 is disposed in the second pore 202 and is a carbon film formed by gas carburizing.

[0165] The carbon content of the carbon ceramics is 20% by weight.

[0166] The carbon ceramic vessel has a water absorption rate of 0.6 wt%, a thermal conductivity of 8 W / (m·K), and a surface roughness of Ra0.7 μm.

[0167] <Preparation Method of Carbon Ceramic Vessels>

[0168] The method for preparing the carbon ceramic vessel in this embodiment includes the following steps:

[0169] I. Substrate Preparation

[0170] 1. Mechanical polishing of the ceramic body (i.e., the first polishing treatment): Red clay ceramic is selected and subjected to ball milling, dehydration and drying, clay kneading and spinning, and drying in sequence to prepare the following: Figure 1 The ceramic preform shown has a cavity 3. Subsequently, the ceramic preform is mechanically polished to achieve a surface roughness of Ra 3 μm.

[0171] 2. The ceramic blank after polishing the pressure plate is sintered at 1250℃ for 15 hours to obtain the sintered ceramic blank.

[0172] II. Liquid carburizing

[0173] 1. Preparation of liquid carbon source (i.e., first carbon source solution): Dissolve 25g of sucrose in 175mL of deionized water and stir thoroughly to obtain a liquid carbon source with a solid content of 12.5%.

[0174] 2. The sintered ceramic body is subjected to degreasing, dehumidification and drying pretreatment to obtain the pretreated ceramic body.

[0175] 3. Immerse the pretreated ceramic body completely in the liquid carbon source at room temperature, keep it for 2.5 hours, and then dry it. Repeat the above immersion and drying process 3 times. The liquid carbon source can penetrate into the pores of the ceramic through capillary action to obtain the immersed ceramic body.

[0176] 4. Place the impregnated ceramic body into a high-temperature sintering furnace and carbonize it at 1000℃ for 3.5 hours under vacuum conditions, then cool it to obtain a liquid carburized ceramic body.

[0177] Tests showed that liquid carburizing can form a carbon film (i.e., the first carbon film) in the larger pores (i.e., the first pores with a diameter of more than 10 μm) inside the ceramic, and the water absorption rate is reduced by 2 / 3.

[0178] III. Gas Carburizing

[0179] The ceramic blank after liquid carburization was placed in a heat treatment atmosphere furnace with nitrogen as the protective gas atmosphere and methane as the carbon source, and held at 800℃ for 8.5h to obtain the carburized ceramic blank.

[0180] The volume of the protective gas is mL, and the volume of methane is n L. m and n satisfy: n / (m+n)=7.5%, m+n=10L.

[0181] Testing revealed that gas carburizing can form a carbon film (i.e., a second carbon film) within the smaller pores (i.e., the second pores with a diameter of less than 10 μm) inside the ceramic, and the water absorption rate is reduced to 0.6%.

[0182] IV. Second Polishing Treatment

[0183] The ceramic body, after liquid carburizing and gas carburizing in step three, was polished using silicon carbide and a specialized polishing fixture. The required surface roughness Ra after polishing was 0.7 μm. Subsequently, the bottom of the product was ground to obtain the carbon ceramic vessel of this embodiment.

[0184] Example 2

[0185] This embodiment is basically the same as embodiment 1, except that:

[0186] The carbon content of carbon ceramic vessels is 10% by weight.

[0187] The carbon ceramic vessel has a water absorption rate of 1 wt%, a thermal conductivity of 2 W / (m·K), and a surface roughness of 0.9 μm.

[0188] In the preparation method of carbon ceramic vessels:

[0189] In the liquid carburizing process:

[0190] In step 1, 10g of sucrose is dissolved in 190mL of deionized water and stirred thoroughly to obtain a liquid carbon source with a solid content of 5%; in step 3, after maintaining for 1 hour, it is dried, and then the above impregnation and drying process is repeated twice; in step 4, the carbonization temperature is 800℃.

[0191] In the gas carburizing process:

[0192] The volume of the protective gas is mL, and the volume of methane is n L. m and n satisfy: n / (m+n)=5%, m+n=10L; keep warm at 700℃ for 5h.

[0193] Example 3

[0194] This embodiment is basically the same as embodiment 1, except that:

[0195] Carbon-fired ceramic vessels contain 30% carbon by weight.

[0196] The carbon ceramic vessel has a water absorption rate of 0.2 wt%, a thermal conductivity of 10 W / (m·K), and a surface roughness of 0.1 μm.

[0197] In the preparation method of carbon ceramic vessels:

[0198] In the liquid carburizing process:

[0199] In step 1, 40g of sucrose is dissolved in 160mL of deionized water and stirred thoroughly to obtain a liquid carbon source with a solid content of 20%; in step 3, after maintaining for 4 hours, it is dried, and then the above impregnation and drying process is repeated 5 times; in step 4, the carbonization temperature is 1200℃.

[0200] In the gas carburizing process:

[0201] The volume of the protective gas is mL, and the volume of methane is n L. m and n satisfy: n / (m+n)=10%, m+n=10L; keep warm at 900℃ for 5h.

[0202] Example 4

[0203] This embodiment is basically the same as embodiment 1, except that:

[0204] The surface roughness of the carbon ceramic vessel is 0.5 μm; the carbon content of the carbon ceramic vessel is 21% by weight.

[0205] In the preparation method of carbon ceramic vessels:

[0206] In the step of polishing the ceramic body by pressing the plate (i.e., the first polishing process), the surface roughness of the ceramic body is made to reach Ra2μm.

[0207] Example 5

[0208] This embodiment is basically the same as embodiment 1, except that:

[0209] The surface roughness of the carbon ceramic vessel is 1 μm; the carbon content of the carbon ceramic vessel is 19% by weight.

[0210] In the preparation method of carbon ceramic vessels:

[0211] In the process of polishing the ceramic body by pressing the plate (i.e., the first polishing process), the surface roughness of the ceramic body is made to reach Ra4μm.

[0212] Example 6

[0213] This embodiment is basically the same as embodiment 1, except that:

[0214] The carbon content of the carbon-fired ceramic vessel is 14% by weight.

[0215] In the preparation method of carbon ceramic vessels:

[0216] Preparation of liquid carbon source (i.e., first carbon source solution): Dissolve 10g of sucrose in 190mL of deionized water and stir thoroughly to obtain a liquid carbon source with a solid content of 5%.

[0217] Example 7

[0218] This embodiment is basically the same as embodiment 1, except that:

[0219] The carbon content of carbon ceramic vessels is 25% by weight.

[0220] In the preparation method of carbon ceramic vessels:

[0221] Preparation of liquid carbon source (i.e., first carbon source solution): Dissolve 40g of sucrose in 160mL of deionized water and stir thoroughly to obtain a liquid carbon source with a solid content of 20%.

[0222] Example 8

[0223] This embodiment is basically the same as embodiment 1, except that:

[0224] In the preparation method of carbon ceramic vessels:

[0225] Preparation of liquid carbon source (i.e., first carbon source solution): Dissolve 25g of phenolic resin in 175mL of ethanol and stir thoroughly to obtain a liquid carbon source with a solid content of 12.5%.

[0226] Example 9

[0227] This embodiment is basically the same as embodiment 1, except that:

[0228] The carbon content of carbon ceramic vessels is 15% by weight.

[0229] In the preparation method of carbon ceramic vessels:

[0230] In the gas carburizing step, the volume of the protective gas is mL and the volume of methane is n L. m and n satisfy: n / (m+n)=5% and m+n=10L.

[0231] Example 10

[0232] This embodiment is basically the same as embodiment 1, except that:

[0233] The carbon content of the carbon-fired ceramic vessels is 24% by weight.

[0234] In the preparation method of carbon ceramic vessels:

[0235] In the gas carburizing step, the volume of the protective gas is mL and the volume of methane is n L. m and n satisfy: n / (m+n)=10%, m+n=10L.

[0236] Example 11

[0237] This embodiment is basically the same as embodiment 1, except that:

[0238] In the preparation method of carbon ceramic vessels:

[0239] In the gas carburizing process, the protective gas is carbon monoxide.

[0240] Example 12

[0241] This embodiment is basically the same as embodiment 1, except that:

[0242] The carbon content of the carbon-fired ceramic vessel is 26% by weight.

[0243] In the preparation method of carbon ceramic vessels:

[0244] In the blank pressing and polishing step (i.e. the first polishing process), kaolin ceramics are selected.

[0245] The ceramic blank, after being polished by the pressure plate, was sintered at 1350℃ for 17 hours to obtain the sintered ceramic blank.

[0246] Example 13

[0247] This embodiment is basically the same as embodiment 1, except that:

[0248] The carbon content of carbon ceramic vessels is 27% by weight.

[0249] In the preparation method of carbon ceramic vessels:

[0250] In the blank pressing and polishing step (i.e., the first polishing process), cordierite ceramics are selected.

[0251] The ceramic blank, after being polished by the pressure plate, was sintered at 1350℃ for 12 hours to obtain the sintered ceramic blank.

[0252] Example 14

[0253] This embodiment is basically the same as embodiment 1, except that:

[0254] The carbon content of the carbon-fired ceramic vessel is 29% by weight.

[0255] In the preparation method of carbon ceramic vessels:

[0256] In the blank pressing and polishing step (i.e., the first polishing process), cordierite ceramics are selected.

[0257] The ceramic blank, after being polished by the pressure plate, was sintered at 1250℃ for 12 hours to obtain the sintered ceramic blank.

[0258] Example 15

[0259] This embodiment is basically the same as embodiment 1, except that:

[0260] The carbon content of the carbon ceramics is 17% by weight.

[0261] The carbon ceramic vessel has a water absorption rate of 0.8 wt%, a thermal conductivity of 6 W / (m·K), and a surface roughness of Ra 0.7 μm.

[0262] In the preparation method of carbon ceramic vessels:

[0263] After pretreatment, the sintered ceramic green body obtained in step one (matrix preparation) undergoes gas carburizing followed by liquid carburizing. That is:

[0264] Step two is gas carburizing, specifically: the sintered ceramic body is degreased, dehumidified and dried pre-treated to obtain a pre-treated ceramic body; then, the pre-treated ceramic body is placed in a heat treatment atmosphere furnace, with nitrogen as the protective gas atmosphere and methane as the carbon source, and held at 800℃ for 8.5h to obtain a gas carburized ceramic body.

[0265] The volume of the protective gas is mL, and the volume of methane is n L. m and n satisfy: n / (m+n)=7.5%, m+n=10L.

[0266] Tests showed that after gas carburizing, a carbon film can be formed in the smaller pores (i.e., the second pores, with a pore size of less than 10 μm) inside the ceramic, and the water absorption rate is reduced to 4.5 wt%.

[0267] Step three is liquid carburizing, specifically:

[0268] 1. Preparation of liquid carbon source (i.e., first carbon source solution): Dissolve 25g of sucrose in 175mL of deionized water and stir thoroughly to obtain a liquid carbon source with a solid content of 12.5%.

[0269] 2. The gas-carburized ceramic body is completely immersed in the liquid carbon source at room temperature and kept for 2.5 hours before drying. The above immersion and drying process is repeated 3 times. The liquid carbon source can penetrate into the ceramic pores through capillary action to obtain the impregnated ceramic body.

[0270] 3. The impregnated ceramic body is placed in a high-temperature sintering furnace and carbonized at 1000℃ for 3.5 hours under vacuum conditions, and then cooled to obtain the carburized ceramic body.

[0271] Tests showed that after liquid carburizing, a carbon film can be formed in the larger pores (i.e., the first pores, with a pore size of more than 10 μm) inside the ceramic, and the water absorption rate is reduced to 0.8 wt%.

[0272] Comparative Example 1

[0273] This comparative example is as follows: Figure 3 The structure shown is a 4L ordinary ceramic pot. That is, the surface of the sintered ceramic body in Example 1 is covered with a glaze layer and does not contain a carbon film.

[0274] The preparation method of the ordinary ceramic pot in this comparative example is as follows:

[0275] Red clay ceramics were successively ball-milled, dehydrated and dried, kneaded and spun into shape, and dried again to prepare ordinary ceramic pot blanks. These blanks were then sintered at 1250℃ for 12 hours to obtain sintered ordinary ceramic pot blanks. Finally, a glaze layer was formed on the surface of the sintered ordinary ceramic pot blanks.

[0276] Comparative Example 2

[0277] This comparative example is basically the same as Example 1, except that:

[0278] The carbon content of carbon ceramic vessels is 4% by weight.

[0279] In the preparation method of carbon ceramic vessels:

[0280] Steps that do not involve liquid carburizing.

[0281] Comparative Example 3

[0282] This comparative example is basically the same as Example 1, except that:

[0283] The carbon content of carbon ceramic vessels is 6% by weight.

[0284] In the preparation method of carbon ceramic vessels:

[0285] The process of carburizing without gas is called carburizing.

[0286] [Performance Testing]

[0287] Test method for thermal conductivity: Add 2.1L of water at 25°C to the ceramic pot of the example or comparative example, heat it with a 600W heating plate, and record the time it takes for the water temperature to rise from room temperature to boiling.

[0288] Water absorption rate test method: Take 10g samples from the bottom and side wall of the ceramic pot of the example or comparative example, put them in an oven at 110℃ for 1 hour, then boil them in boiling water for 3 hours, stop heating and let the samples soak in water until room temperature, and measure their weight gain after the test.

[0289] Test method for water permeability: After filling the ceramic pot of the example or comparative example with water, let it stand for 24 hours, and visually inspect it. There should be no watermarks on the outside and bottom.

[0290] The test results of thermal conductivity, water absorption rate and water permeability of the ceramic pots in each embodiment and comparative example are shown in Table 1. The test results of water absorption rate of ceramic liquid and gas before and after carburizing treatment in Examples 1, 12-14 are shown in Table 2.

[0291] Table 1. Performance test results of ceramic pots in each embodiment and comparative example.

[0292]

[0293] Note: In Table 1, "OK" means that there should be no watermarks on the outside and bottom of the ceramic pot, and "NG" means that there are watermarks on the outside and bottom of the ceramic pot.

[0294] As can be seen from Table 1:

[0295] Ordinary heat-resistant ceramics have poor thermal conductivity. The thermal conductivity of daily-use ceramics mainly relies on lattice vibration, resulting in low heat transfer efficiency. Furthermore, ceramics have high porosity, leading to high thermal resistance during the heat transfer process.

[0296] When ceramics undergo liquid + gas carburizing, the internal pores are basically eliminated, the water absorption rate is ≤3.5wt%, and the pores inside the ceramics are occupied by carbon film, forming a highly thermally conductive channel, thus greatly improving the heat transfer efficiency.

[0297] When ceramics are carburized with liquid or gas alone, their thermal conductivity is significantly improved. However, compared with liquid + gas co-carburization, there are still many pores inside, which form thermal resistance.

[0298] Table 2. Test results of water absorption rate of ceramic liquid and gas before and after carburizing treatment in Examples 1, 12-14.

[0299]

[0300] As can be seen from Table 2, the water absorption rate after liquid + gas carburizing is ≤3.5%, and the carbon content is above 17wt%.

[0301] Figure 5 This is a scanning electron microscope (SEM) image of the carbon ceramic vessel prepared in Example 1. From... Figure 5 It can be seen that during the liquid carburizing process, the liquid penetrates into pores with a diameter of 10 μm or more, while during the gas carburizing process, the liquid penetrates into smaller pores (with a diameter of less than 10 μm), further filling the ceramic pores and reducing the water absorption rate.

[0302] In this application, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0303] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0304] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A method for preparing carbon ceramic vessel, characterized in that, include: The ceramic blank is first polished to obtain the polished ceramic blank. The polished ceramic blank is sintered to obtain a sintered ceramic blank. The sintered ceramic body is subjected to liquid carburizing and gas carburizing to obtain a ceramic body containing a carbon film in at least some of the pores. The ceramic body containing a carbon film in at least some of its pores is subjected to a second polishing process to obtain the carbon ceramic vessel.

2. The preparation method according to claim 1, characterized in that, The surface roughness of the ceramic body after the first polishing treatment is a μm, and the surface roughness of the carbon ceramic vessel after the second polishing treatment is b μm, where b is less than a.

3. The preparation method according to claim 2, characterized in that, The condition 'a' satisfies: 2≦a≦4; And / or, the b satisfies: b≦1.

4. The preparation method according to claim 1, characterized in that, The first polishing process includes at least one of mechanical polishing and manual polishing. And / or, the second polishing process includes at least one of abrasive polishing and mechanical polishing; And / or, the sintered ceramic body is first subjected to liquid carburizing, and then to gas carburizing, to obtain a ceramic body containing a carbon film in at least some of the pores.

5. The preparation method according to claim 1, characterized in that, The liquid carburizing includes: The sintered ceramic body or the gas-carburized ceramic body is repeatedly impregnated with a first carbon source solution, and a first drying treatment is performed after each impregnation treatment to obtain an impregnated ceramic body. The impregnated ceramic blank is carbonized in a vacuum or a first reducing gas atmosphere.

6. The preparation method according to claim 5, characterized in that, The first carbon source solution includes at least one of phenolic resin solution and sucrose solution; And / or, the solid content in the first carbon source solution is 5-20 wt%; And / or, the duration of each impregnation treatment is 1-4 hours; And / or, the number of impregnation treatments is 2-5 times; And / or, the carbonization treatment temperature is 800-1200℃, and the carbonization treatment time is 2-5h.

7. The preparation method according to claim 1, characterized in that, The gas carburizing includes: The ceramic preform after liquid carburization or the sintered ceramic preform is subjected to chemical vapor infiltration.

8. The preparation method according to claim 7, characterized in that, The second carbon source for chemical vapor infiltration includes at least one of alkanes, alkenes, alkyl acids, and small molecule alcohols; And / or, the chemical vapor permeation is carried out under a protective gas atmosphere, the volume of the protective gas is mL, the volume of the second carbon source after vaporization is n L, and the m and n satisfy: 5% ≤ n / (m+n) ≤ 10%; And / or, the temperature of the chemical vapor infiltration is 700-900°C, and the time of the chemical vapor infiltration is 5-12 hours.

9. The preparation method according to claim 1, characterized in that, The ceramic body comprises at least one of red clay ceramic, kaolin ceramic, and cordierite ceramic, and the sintering temperatures of the red clay ceramic, kaolin ceramic, and cordierite ceramic are 1100-1200℃, 1300-1400℃, and 1200-1300℃, respectively. And / or, the method for preparing the carbon ceramic vessel further includes the steps of ball milling, dehydration and drying, kneading and spinning into shape, and second drying to obtain the ceramic body; And / or, the ceramic blank has a receiving cavity; And / or, the carbon ceramic vessel is a cooking utensil.

10. A type of carbon ceramic vessel, characterized in that, The carbon ceramic vessel is prepared by the method described in any one of claims 1 to 9; the carbon ceramic vessel includes the sintered ceramic body and the carbon film; the carbon film is disposed in at least a portion of the pores of the sintered ceramic body.

11. The carbon ceramic vessel according to claim 10, characterized in that, The carbon content of the carbon ceramic vessel is 10-30% by weight.

12. The carbon ceramic vessel according to claim 10, characterized in that, The water absorption rate of the carbon ceramic vessel is below 3.5 wt%. And / or, the thermal conductivity of the carbon ceramic vessel is 2-10 W / (m·K); And / or, the surface roughness of the carbon ceramic vessel is below 1 μm.

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