Method for producing porous carbon or graphite

Abstract

Method for producing porous carbon or graphite. The invention is based on the problem of creating a method for the cost-effective production of porous carbon or graphite from renewable raw materials, which is easy to implement and allows a mechanical post-processing for the production of any shaped article, for use as a structural element, mould or container. This is achieved by filling a mold / container (1) with powdered dry or dehydrated wheat- or rice starch as a dense mass; compressing / densifying the mass (2) in the mold / container (1); heating the mass (2) in said filled mold / container (1) in an oven to a first temperature level of 170°C to 450°C in an oxidizing or inert atmosphere, thereby causing a shrinkage process; stabilizing the heated mass (2) for a longer time; slowly further heating the mass (2) in an oven under protective gas to a second temperature level of >1,000°C for carbonization or >2,500°C for graphitization to form a blank (5) that is as dense as possible; and removing the dense blank (5) from the mold / container (5).

Description

【Technical Field】 【0001】 The present invention relates to a method for producing porous carbon or graphite having a uniform and hard structure suitable for mechanical processing for manufacturing molded articles. 【Background Art】 【0002】 The production of carbon materials is usually carried out by pulverizing coke, carbon black or graphite until a granular material or powder having a desired particle size is obtained. Since deformation by simple compression of these granular materials is impossible, a suitable binder, such as a thermoplastic plastic, is mixed with the granular materials. Then, this mixture is homogenized and formed into a desired shape by compression. The molded body thus produced is also called a green compact and is finally carbonized or graphitized at a high temperature under a suitable atmosphere in a furnace. 【0003】 Following carbonization / graphitization, mechanical processing for manufacturing carbon parts or graphite parts can then be continued. 【0004】 Needless to say, the above manufacturing process is very laborious and very expensive due to the starting materials used. 【0005】 From CN113620272A (Cited Document 1), a method for manufacturing a graphite-made battery electrode is known in which starch and carbon black are first mechanically and uniformly mixed with each other at a predetermined ratio. Then, the mixture is put into a crucible and stabilized in a muffler furnace at 200 to 600°C for 3 to 8 hours. Finally, the mixture is carbonized in a nitrogen atmosphere at 800 to 1,600°C for 1 to 3 hours to produce carbon microspheres based on carbon black, and then cooled to room temperature. 【Prior Art Documents】 【Patent Documents】 【0006】 [Patent Document 1] CN113620272A [Overview of the project] [Problems that the invention aims to solve] 【0007】 Therefore, the present invention provides an easily implementable method for cost-effectively producing porous carbon or graphite having a uniform and rigid structure from renewable raw materials. Building materials This is based on the challenge of creating a method that enables mechanical post-processing for the manufacture of any molded product, which can be used as a mold or container and can be easily converted into a SiC molded product. [Means for solving the problem] 【0008】 The problem underlying the present invention is solved by the following method steps: - Step of filling a mold / container with powdered dry or dried wheat, corn, rice or other starch, - The step of creating a dense mass in a mold / container by compressing / densifying the mass in the container by applying uniform pressure or impulse pressure to the mass. - A step of causing a shrinkage process by slowly heating the dense mass in the filled mold / container in a furnace to a first temperature level of 170°C to 450°C in 5°C steps, in an oxidizing or inert atmosphere, while further compressing / densifying the mass. - A step to stabilize the blank over a relatively long period of time, exceeding one hour. - The steps of slowly further heating the blank in a furnace under protective gas at a temperature gradient of approximately 1°C / min to a second temperature level of >1,000°C for carbonization or >2,500°C for graphitization, thereby forming a blank as dense as possible, and - The step of removing the precise blank from the mold / container. 【0009】 The fundamental problem underlying the present invention is further solved by the following method steps: - Step of filling a mold / container with powdered dry or dried wheat, corn, rice or other starch, - The step of creating a dense mass in a mold / container by compressing / densifying the mass in the container by applying uniform pressure or impulse pressure to the mass. - A step of causing a shrinkage process by heating the dense mass to a starting temperature of approximately 190°C, followed by a cooling process over several hours, and then continuously reheating the dense mass to 210-230°C while further compressing / densifying the mass. - A step to stabilize the heated mass over a relatively long period of time, exceeding one hour. - The steps of slowly further heating the block in a furnace under protective gas at a temperature gradient of approximately 1°C / min to a second temperature level of >1,000°C for carbonization or >2,500°C for graphitization, to form the densest possible blank, and - The step of removing the precise blank from the mold / container. 【0010】 Preferably, the slow heating to the first temperature level is carried out in steps of 5°C, with a waiting time of approximately 8 hours between each step. 【0011】 Wheat starch, corn starch, or rice starch can also be mixed with sugar or vegetable oil as a binder. 【0012】 In yet another embodiment, a mixture of wheat starch or rice starch and sugar or oil (edible oil) is mixed with an additional foreign substance, which is yet another graphitizable material. 【0013】 Examples of materials that can be graphitized include high-temperature resistant polymers, carbon black, graphite dust, natural graphite, and PVA (polyvinyl alcohol) adhesives. 【0014】 Finally, natural fiber materials such as cotton, cellulose, bamboo, hemp, etc. can also be mixed. 【0015】 In continuation of the present invention, the compression / high densification of the mass filled in the mold / container is achieved, for example, by a weight, by applying an additional load to a plate placed on the mass to generate a uniform pressure acting on the mass, or by vibration (e.g., using a vibrating plate or another vibrating device), or by shaking (Schuetteln) of the mold / container, or by a strong impact acting horizontally or from below on the mass, for example, by hitting the mold / container, resulting in a dense molded article. 【0016】 The compression / high densification of the mass can also be carried out during heating by applying a load with a weight placed on top. 【0017】 The heating gradient for carbonization or graphitization is about 1 °C / min or less, and a rest of about 30 - 120 minutes should be introduced every 50 - 100 °C, so that the material relaxes and at the same time gases such as air or steam can diffuse out without damaging the structure. 【0018】 [[ID=1 six]] The specific selection of the heating gradient and heating steps also depends on the pressure during this process, so that at a higher pressure, heating can be carried out more rapidly overall. 【0019】 Examples of protective gases include noble gases, namely helium, neon, argon, krypton, xenon, and radon. 【0020】 Carbonization or graphitization is preferably carried out at a pressure > 500 mbar. 【0021】 Preferably, in order to enable easy removal of the molded article, a mold / container made of Teflon (up to a maximum temperature of 250 °C) or another suitable material can be used, or the inside of the mold / container can be covered with a cloth before filling the mass. 【0022】 The blank 5 made of graphite produced by the present invention can be successfully converted into SiC at a temperature of 1,200°C while supplying SiO using argon as a carrier gas at a pressure of 30 mbar in a furnace. Here, a temperature of about 1,520°C is preferred. 【0023】 Hereinafter, the present invention will be described in more detail using examples. The following are shown in the following drawings. 【Brief Description of the Drawings】 【0024】 FIG. 1a shows a mold / container filled with a mixture of wheat starch and foreign substances. 【0025】 FIG. 1b shows the filled container after carbonization. 【0026】 FIG. 2 shows a container whose inside is covered with a cloth. 【0027】 FIG. 3 shows a carbonized mass produced from wheat starch, sugar, and edible oil as a foreign substance after the first heating to 250°C. 【0028】 FIG. 4 shows a blank after 3 hours at 1600°C that was heated at a heating rate of 1°C / min and held at 200°C, 400°C, and 500°C for 120 minutes each during the temperature increase. 【0029】 FIG. 5 shows the blank of FIG. 4 completed as a molded body after cutting on both sides (outer and inner). 【0030】 The method according to the present invention initially includes the following steps: The process involves filling a mold / container 1 with powdered / granular dry or dried wheat starch or rice starch as a dense mass 2, followed by a step of densifying the mass 2 within the mold / container 1 (Figure 1a). To achieve this, the mass 2 filled in the mold / container 1 is densified by generating uniform pressure acting on the mass 2, for example by applying further load to a plate placed on top of the mass 2 using weights, or by vibration (using, for example, a vibrating plate or another vibrating device), shaking the mold / container, or by violent impacts acting on the mass 2 from the side or below, for example by striking the mold / container 1, resulting in a dense mass 2. 【0031】 Alternatively, a binder may be mixed with wheat starch or corn starch. 【0032】 As a binder for the production of the aforementioned mixture, sugar or oil, such as edible oil, is particularly suitable. 【0033】 It is also possible to mix another graphitizable material with lump 2 made from wheat starch or rice starch and sugar or oil (edible oil). 【0034】 Other materials that can be graphitized include, for example, high-temperature resistant polymers, carbon black, graphite dust, natural graphite, and PVA (polyvinyl alcohol) adhesives. 【0035】 Finally, natural fiber materials, such as cotton, cellulose, bamboo, and hemp, can also be mixed in. 【0036】 Next, the dense or densified mass 2 in the filled mold / container 1 is heated in a furnace to a first temperature level of 170°C to 450°C in an oxidizing or inert atmosphere, or at >170°C, thereby inducing a shrinkage process and stabilizing the mass 2 in the mold / container 1 for a longer period of time. The stabilization takes place over a period of >1 hour, depending on the amount of mass 2. Figure 1b shows the at least partially carbonized mass 3 after the first heat treatment, and Figure 3 shows the at least partially carbonized mass 3 from different viewpoints after being removed from the mold / container 1. 【0037】 Alternatively, the shrinkage process can also be brought about by rapidly heating the dense mass 2 to a starting temperature of approximately 190°C, followed by a cooling process over several hours, and then slow, continuous reheating of the dense mass to 210–230°C. 【0038】 The shrinkage process is best induced by gradually and slowly heating the material to approximately 180°C and then 230°C. 【0039】 The mold / container 1 may be made of a heat-resistant plastic or other material so that the stabilized mass 3 can be easily removed, or the inside of the mold / container 1 may be lined with a cloth 4 before filling with the mass (Figure 2). 【0040】 In the next step, the at least partially carbonized mass 3 is heated in the furnace, under a protective gas, on a heating gradient, to a second temperature level of >1,000°C for carbonization or >2,500°C for graphitization, to form a blank 5 that is as dense as possible, which can then be removed from the mold / container 1. Examples of protective gases include noble gases such as helium, neon, argon, krypton, xenon, and radon. In principle, N2 can also be used. 【0041】 Needless to say, blank 5 can also be removed from mold / container 1 and subjected to heat treatment in a furnace, even before carbonization / graphitization. 【0042】 The heating gradient for carbonization or graphitization of blank 5 should be, for example, less than about 1°C / min, with pauses of about 30-120 minutes introduced for every 50-100°C step, thereby allowing the material to relax and simultaneously allowing gases, such as air or water vapor, to diffuse out without damaging the structure. Carbonization or graphitization is preferably carried out at a pressure of >500 mbar. 【0043】 Needless to say, depending on the amount of blank space, other gradients are also possible. 【0044】 Figure 4 shows Blank 5 after heat treatment at a final temperature of 1,600°C for approximately 3 hours with a heating gradient of 1°C / min, stopping at 200°C, 300°C, 400°C, and 500°C for 120 minutes each. 【0045】 Figure 5 shows the blank 5 from Figure 4, which has been mechanically processed as a molded body 6 after cutting on both sides (outside and inside). 【0046】 Blank 5, made of graphite and manufactured according to the present invention, can also be converted to SiC without any problems. The conversion to SiC can be carried out in a furnace at a temperature of >1200°C, under the supply of SiO with argon as a carrier gas, and at a pressure of 30 mbar, as is customary. The preferred temperature for this process is 1520°C. 【0047】 The conversion to SiC can also be carried out under high pressure, for example, at 950 mbar. The pressure actually used will affect the uniformity and speed of the conversion. 【0048】 In principle, during carbonization / graphitization in the furnace, it is also possible to supply additional carbon-containing gas, which results in further increasing the density of the molded body 6. While this application relates to the invention described in the claims, it may also encompass the following other embodiments. 1. A simple method for producing porous carbon or graphite having a uniform and rigid structure, - Steps of filling a mold / container (1) with powdered dry or dehydrated wheat starch, corn starch, rice starch or other starch, - A step of generating a dense mass (2) in a mold / container (1) by compressing / densifying the mass (2) in the container (1) by applying uniform pressure or impulse pressure to the mass (2), - A step of causing a shrinkage process by heating the dense mass (2) in the filled mold / container (1) in a furnace to a first temperature level of 170°C to 450°C in steps of 5°C, in an oxidizing or inert atmosphere, while further compressing / densifying the mass (2). - A step to stabilize the heated mass (2) for a period of more than one hour, - The steps of slowly further heating the block (2) in a furnace with a temperature gradient of approximately 1°C / min under protective gas to a second temperature level of >1,000°C for carbonization or to a second temperature level of >2,500°C for graphitization to form a blank (5) that is as dense as possible, and - Step of removing the fine blank (5) from the mold / container, The manufacturing method characterized by the above. 2. A simple method for producing porous carbon or graphite having a uniform and rigid structure, - Steps of filling a mold / container (1) with powdered dry or dehydrated wheat starch, corn starch, rice starch or other starch, - The process involves compressing / densifying a dense mass (2) within a container (1) by applying uniform pressure or impulse pressure to the mass (2), - A step of heating the dense mass (2) to a starting temperature of approximately 190°C, followed by a cooling process over several hours, and then continuously reheating the dense mass (2) to 210-230°C while further compressing / densifying the mass (2) to induce a shrinkage process. - A step to stabilize the heated mass (2) over a relatively long period of time, exceeding 1 hour. - The steps of slowly further heating the block (2) in a furnace with a temperature gradient of approximately 1°C / min under protective gas to a second temperature level of >1,000°C for carbonization or to a second temperature level of >2,500°C for graphitization to form a blank (5) that is as dense as possible, and - Step of removing the fine blank (5) from the mold / container, The manufacturing method characterized by the above. 3. The method according to 1 or 2 above, characterized in that wheat starch or rice starch is mixed with sugar or oil as a binder. 4. The method according to any one of 1 to 3 above, characterized in that wheat starch or rice starch, or a mixture of wheat starch or rice starch and sugar or oil (edible oil), is further mixed with another graphitizable material. 5. The method according to item 4, characterized in that a high-temperature resistant polymer, carbon black, graphite dust, natural graphite, and PVA (polyvinyl alcohol) adhesive are mixed as further graphitizable materials. 6. The method according to any one of 1 to 5 above, characterized in that wheat or corn starch or a mixture is mixed with a natural fiber material, such as cotton, cellulose, bamboo, or hemp. 7. The method according to any one of 1 to 6 above, characterized in that the compression / densification of the mass (2) filled in the mold / container (1) is carried out, for example, by applying a further load to a plate placed on the mass (2) by a weight, thereby generating a uniform pressure acting on the mass (2), or by vibration or shaking of the mold / container (1), or by a violent impact acting on the mass (2) from the side or from below, for example by striking the mold / container (1). 8. The method according to 1 or 2 above, characterized in that the heating of the block (2) for carbonization is carried out in multiple stages, with a pause of approximately 30 to 120 minutes introduced at each stage of heating to 50 to 100°C. 9. The method according to 1 or 2 above, characterized in that a noble gas such as helium, neon, argon, krypton, xenon, or radon is used as a protective gas. 10. The method according to 1 or 2 above, characterized in that carbonization or graphitization is carried out at a pressure of >500 mbar. 11. The method according to 1 or 2 above, characterized in that a mold / container (1) made of Teflon is used and / or the inside of the mold / container (1) is covered with a cloth (4) before filling with a mass. 12. The method according to any one of 1 to 11 above, characterized in that a graphite blank (5) manufactured in accordance with the present invention is converted to SiC in a furnace at a temperature of >1,200°C, while SiO is supplied together with argon as a carrier gas, at a pressure of 30 mbar. 13. The method according to 12 above, characterized in that the conversion to SiC is carried out at a temperature of approximately 1,520°C. 【0049】 Method for producing porous carbon or graphite [Explanation of symbols] 【0050】 Code List 1 type / container 2. Dense mass 3. Carbonized mass 4 Fabric 5 Blank 6. Molded body

Claims

[Claim 1] A simple method for producing porous carbon or graphite having a uniform and rigid structure for use as a building component, mold or container, - A step of filling a mold / container (1) with powdered dry or dehydrated wheat starch, corn starch, rice starch or other starch. - A step of generating by compressing / densifying a dense mass (2) in a mold / container (1) by applying constant pressure or impulsive pressure to the mass (2) in the container (1), - A step of causing a shrinkage process by heating the dense mass (2) in the filled mold / container (1) in a furnace to a first temperature level of 170°C to 450°C in steps of 5°C with a waiting time between each step, in an oxidizing or inert atmosphere, while further compressing / densifying the mass (2). - A step to stabilize the heated mass (2) for a period of more than one hour, - The steps of slowly further heating the block (2) in a furnace with a temperature gradient of 1°C / min under protective gas to a second temperature level of >1,000°C for carbonization or to a second temperature level of >2,500°C for graphitization, to form a blank (5) that is as dense as possible, and - Step of removing the fine blank (5) from the mold / container, The manufacturing method characterized by the above. [Claim 2] A simple method for producing porous carbon or graphite having a uniform and rigid structure for use as a building component, mold or container, - A step of filling a mold / container (1) with powdered dry or dehydrated wheat starch, corn starch, rice starch or other starch. - The process involves compressing / densifying a dense mass (2) within a container (1) by applying constant pressure or impulsive pressure to the mass (2), - A step of causing a shrinkage process by heating the dense mass (2) to a starting temperature of 190°C, followed by a cooling process for a period of more than one hour, and then continuously reheating the dense mass (2) to 210-230°C while further compressing / densifying the mass (2), - A step to stabilize the heated mass (2) over a relatively long period of time exceeding one hour, - The steps of slowly further heating the block (2) in a furnace with a temperature gradient of 1°C / min under protective gas to a second temperature level of >1,000°C for carbonization or to a second temperature level of >2,500°C for graphitization, to form a blank (5) that is as dense as possible, and - Step of removing the fine blank (5) from the mold / container, The manufacturing method characterized by the above. [Claim 3] The method according to claim 1 or 2, characterized in that wheat starch or rice starch is mixed with sugar or oil as a binder. [Claim 4] The method according to claim 1 or 2, characterized in that wheat starch or rice starch, or a mixture of wheat starch or rice starch and sugar or oil, is further mixed with another graphitizable material. [Claim 5] The method according to claim 4, further characterized in that a high-temperature resistant polymer, carbon black, graphite dust, natural graphite, and polyvinyl alcohol adhesive are mixed as other materials that can be graphitized. [Claim 6] The method according to claim 1 or 2, characterized in that a natural fiber material is mixed with wheat or corn starch or a mixture thereof. [Claim 7] The method according to claim 1 or 2, characterized in that the compression / densification of the mass (2) filled in the mold / container (1) is carried out by generating a constant pressure acting on the mass (2), by vibration or shaking of the mold / container (1), or by a violent impact acting on the mass (2) from the side or below. [Claim 8] The method according to claim 1 or 2, characterized in that the heating of the block (2) for carbonization is carried out in multiple stages, with a pause of 30 to 120 minutes introduced at each stage of heating to 50 to 100°C. [Claim 9] The method according to claim 1 or 2, characterized in that a noble gas such as helium, neon, argon, krypton, xenon, or radon is used as a protective gas. [Claim 10] The method according to claim 1 or 2, characterized in that carbonization or graphitization is carried out at a pressure of >50,000 Pa. [Claim 11] The method according to claim 1 or 2, characterized in that a mold / container (1) made of Teflon is used and / or the inside of the mold / container (1) is covered with a cloth (4) before filling with a mass. [Claim 12] The method according to claim 1 or 2, characterized in that a graphite blank (5) manufactured in accordance with the present invention is converted to SiC in a furnace at a temperature of >1,200°C, while supplying SiO together with argon as a carrier gas, at a pressure of 3,000 Pa. [Claim 13] The method according to claim 12, characterized in that the conversion to SiC is carried out at a temperature of 1,520°C. [Claim 14] The method according to claim 1 or 2, characterized in that a carbon-containing gas is additionally supplied during the carbonization or graphitization in the furnace.

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