Method for producing carbonized or graphitized 3D objects

Abstract

The present invention relates to a method for producing carbonized or graphitized 3D objects, which is based on the task of realizing such objects in a particularly simple manner, by means of which even relatively complex 3D objects can be produced without structural disturbance, which is achieved by mixing a carbonizable or graphitizable material with a flowable organic adhesive or a flowable organic thermoplastic substance to produce a kneadable, substantially form-stable compound and molding this compound to a 3D blank, followed by a drying and outgassing process at elevated temperature for a defined time, followed by carbonization or graphitization of the 3D blank in a furnace under a protective gas atmosphere to produce the 3D object, wherein the temperature required for carbonization or graphitization is approached at a low heating rate.

Description

[Technical field]

[0001] The present invention relates to a method for producing carbonized or graphitized 3D objects. [Background technology]

[0002] Such carbonized or graphitized 3D objects, which are also suitable for use at high temperatures, can be various components, such as furnace linings, building components, or any hollow body, vessel or crucible.

[0003] Since 3D objects cannot be produced by simple molding and subsequent sintering of carbon black or graphite, it is generally necessary to produce suitable carbon-containing and moldable compounds. For this purpose, carbon black, coke or graphite is usually mixed in the form of granules with a suitable binder, for example a thermoplastic binder. Pitches based on coal tar or petroleum pitch, or synthetic resins, are also considered as binders.

[0004] These mixtures are then pressed into green parts and carbonized or graphitized in a furnace at about 3,000°C, during which the binder decomposes into volatile components, leaving behind carbon and binder coke in the form of a porous structure.

[0005] Alternatively, the green part can be placed between electrodes in a furnace as a resistive element and heated by electric current.

[0006] The difficulty in carbonizing or graphitizing such parts is that at the high temperatures required, the volatile substances outgas more or less vigorously, which can lead to structural disturbances such as cracks or gas inclusions. Summary of the Invention [Problem to be solved by the invention]

[0007] The invention is based on the problem of providing a method for producing carbonized or graphitized 3D objects, which is particularly easy to realize and allows even relatively complex 3D objects to be produced without structural disturbances. [Means for solving the problem]

[0008] The object of the present invention is to produce a kneadable and substantially shape-stable compound consisting of a carbonizable or graphitizable material and a flowable organic adhesive or a flowable thermoplastic organic substance, and to manufacture the compound. , by hand forming a 3D blank using a suitable template, or in a mold made of Teflon or silicone. Molding And by removing the 3D blank from this mold, 3D blank, then of the 3D blank at room temperature or up to 100 °C. Drying and gas releasing processes are carried out. This is then converted into a 3D part by a stabilization and homogenization step at temperatures ranging from 140°C up to 450°C in air. Then, this 3D molded product In the furnace Protected Protective Gas atmosphere The 3D object is then carbonized or graphitized under vacuum, where the temperatures required for carbonization or graphitization are achieved by approaching a low heating rate.

[0009] As carbonizable or graphitizable materials, preferably carbon black, graphite powder, natural graphite, cellulose or corn starch, or mixtures of any or all of these materials, etc., come into consideration.

[0010] Bamboo, cotton, hemp, sisal or graphite fibers can be mixed into the carbonizable or graphitizable material while maintaining kneadability in order to affect the strength or porosity of the 3D object produced. 。

[0011] Protection As protective gas, preferably argon or helium is used.

[0012] Alternatively, the 3D blank can be subjected to a stabilization and homogenization step after the drying process at a stabilization temperature of 170°C in air or up to 450°C in air to produce a 3D molded part, with a temperature of 250°C being preferred.

[0013] The stabilization and homogenization steps can in principle also be carried out under a protective gas such as argon.

[0014] Stabilization and homogenization of the 3D blank can also occur during furnace heating.

[0015] In the present invention, the 3D molded article is subsequently carbonized into a 3D object at a constant temperature of about 1,000° C. until pure carbon of various crystal structures is produced.

[0016] In another continuation of the invention, the 3D part is graphitized at a constant temperature above 2,000°C.

[0017] Finally, 3D parts can be fully graphitized at temperatures above 2,500°C.

[0018] Preferably, graphitization is carried out at a heating rate of about 1° C. / min until the desired temperature is reached, followed by heat treatment for about 30 minutes depending on the size of the 3D part.

[0019] In one preferred embodiment of the invention, the kneadable compound can be mixed with metal or silicon powder so that metal carbide or silicon carbide is formed during high temperature treatment of the 3D molded part at >1,000°C under protective gas.

[0020] The graphitized foam 3D object can also be converted to a 3D object made of SiC in a furnace at temperatures >1,200 °C and a pressure of about 30 mbar, supplying gaseous SiO with argon as carrier gas.

[0021] The present invention will now be described in more detail with reference to examples. EXAMPLES

[0022] In the first process step, a kneadable and almost form-stable compound is produced by mixing a carbonizable or graphitizable material with a flowable organic adhesive or a flowable thermoplastic organic substance, which is then molded to form a 3D blank.The 3D blank is then freed from, in particular, moisture and gas inclusions at elevated temperatures in a drying or outgassing process, thereby being converted into a 3D molded part.This makes it possible to avoid the occurrence of cracks during the subsequent carbonization or graphitization of the 3D molded part in a furnace, under vacuum or protective gas, such as argon or helium, to produce a 3D object.

[0023] As carbonizable or graphitizable organic material preferably carbon black, graphite powder, natural graphite, as well as starch, for example corn or potato starch or similar, or mixtures of some or all of these materials can be used.

[0024] To affect the strength or porosity of the finished carbonized or graphitized 3D object, bamboo fibers, cotton fibers, hemp fibers, sisal fibers or other suitable plant fibers, or graphite fibers can be mixed into the carbonizable or graphitizable organic material while maintaining kneadability, if necessary by adding additional flowable adhesives or flowable organic substances until the desired consistency is achieved.

[0025] The shaping of the 3D blank can be carried out, for example, by hand using a template or by molding in a mould, from which the 3D blank should be removed before the drying process. To allow a relatively easy release of the 3D blank, moulds made of Teflon, silicone or other materials with limited elasticity can be used.

[0026] Alternatively, the 3D moulding can be done by removing the water present. To, Drying process at room temperature or up to 100°C SA subsequent stabilization and homogenization step at a stabilization temperature of 140° C. in air or up to 450° C. under protective gas or vacuum (a temperature of 250° C. is preferred) allows outgassing and thus prevents the occurrence of cracks during subsequent carbonization or graphitization.

[0027] It is understood that the 3D part may remain in place during the stabilization or homogenization process.

[0028] Stabilization and homogenization of the 3D part can also occur during furnace heating.

[0029] Stabilization of the 3D part is necessary to prevent its decomposition during carbonization / graphitization, which would otherwise cause it to melt or become severely deformed. During stabilization, the atoms / molecules reorganize so that they can withstand the high temperature processes.

[0030] The 3D mould is then subsequently carbonised into a 3D object in a furnace at a constant temperature of about 1,000° C. until pure carbon with various crystal structures is produced.

[0031] In another continuation of the invention, the 3D molded part is then graphitized in a furnace at a constant temperature of 2,000° C. or higher to form a 3D object.

[0032] Finally, the 3D molded part can be fully graphitized in a furnace at temperatures exceeding 2,500°C for forming of the 3D article.

[0033] It is understood that the carbonization or graphitization must be carried out in a furnace under protective gas in order to avoid combustion of the organic components of the 3D blank.

[0034] While it is in principle certainly possible to carry out carbonization or graphitization under vacuum, in this case there is a risk that the pressure difference between the inside of the 3D part and the vacuum will accelerate the volatile components, which could lead to cracks.

[0035] For this reason, it is advantageous to apply high pressure in the furnace, so that the volatile components diffuse out slowly, thereby ensuring that cracks and breakages are avoided.

[0036] Preferably, carbonization or graphitization is carried out at a heating rate of about 1° C. / min until the target temperature is reached, followed by a temperature treatment for about 30 minutes, although temperature treatment for several hours is also possible.

[0037] In order to achieve uniform carbonization or graphitization, it is important to pre-release the 3D molded part.

[0038] In one particular embodiment of the invention, the kneadable compound can be mixed with metal or silicon powder, so that metal carbide or silicon carbide is formed during high temperature treatment of the 3D molded part at >1,000°C under protective gas.

[0039] The graphitized foam 3D object can also be converted to a 3D object made of SiC in a furnace at temperatures >1,200° C. and a pressure of about 30 mbar, supplying gaseous SiO with argon as carrier gas.

[0040] While this application is directed to the invention set forth in the claims, the disclosure of this application also includes: 1. A method for producing carbonized or graphitized 3D objects, characterized in that a carbonizable or graphitizable material made of carbon black, graphite powder, natural graphite, cellulose or corn starch or a mixture of some or all of these materials is mixed with a flowable organic adhesive or a flowable organic thermoplastic substance to form a kneadable, form-stable compound, which is molded using a mold made of Teflon or silicone to form a 3D blank and then the 3D blank is removed from the mold and a subsequent drying and outgassing process is carried out at room temperature or up to 100°C for a defined time, followed by a stabilization and homogenization step at a temperature of 140°C up to 450°C, followed by carbonization or graphitization of the 3D blank in a furnace under a protective gas atmosphere to produce a 3D object, wherein the temperature required for carbonization or graphitization is approached with a heating rate of 1°C / min and then a temperature treatment is carried out. 2. The method according to claim 1, characterized in that bamboo fiber, cotton fiber, hemp fiber, sisal fiber or graphite fiber is mixed into the material that can be carbonized or graphitized while maintaining kneadability. 3. The method according to claim 1 or 2, characterized in that the shaping of the 3D blank is carried out by hand and / or using a template. 4. The method according to claim 3, wherein stabilization and homogenization of the 3D blank is carried out during heating of the furnace. 5. A method according to any one of 1. to 4. above, characterized in that the 3D moulded part is carbonised under vacuum or protective gas at a constant temperature of 1,000°C until pure carbon with various crystal structures is produced to form a 3D object. 6. The method according to any one of 1. to 5. above, characterized in that the 3D molded part is graphitized in a furnace under vacuum or protective gas at a constant temperature of 2,000°C or higher to form a 3D object. 7. The method according to claim 6, characterized in that the 3D moulding is fully graphitized in a furnace under vacuum or protective gas at a temperature above 2,500°C to form a 3D object. 8. The method according to any one of 1. to 7. above, characterized in that argon or helium is used as the protective gas. 9. The method according to claim 7 or 8, characterized in that graphitization of the 3D molded part using a heating rate of about 1°C / min until the target temperature is reached is followed by a temperature treatment lasting from about 30 minutes to several hours. 10. A method according to any one of claims 1 to 9, characterized in that the kneadable compound is mixed with metal or silicon powder, so that high-temperature treatment of the 3D blank in a furnace under protective gas at temperatures >1,000°C produces a 3D moulded part made of metal carbide or silicon carbide. 11. The method according to any one of claims 1 to 10, characterized in that the graphitized foam 3D object is converted into a 3D object made of SiC in a furnace at a temperature of >1,200 °C and a pressure of 30 mbar while supplying gaseous SiO with argon as carrier gas.

Claims

1. A method for producing a carbonized or graphitized 3D object, characterized in that a carbonizable or graphitizable material made of carbon black, graphite powder, natural graphite, cellulose or corn starch or a mixture of some or all of these materials is mixed with a flowable organic adhesive or a flowable thermoplastic organic substance to form a kneadable, form-stable compound, which is molded using a mold made of Teflon or silicone to form a 3D blank and then the 3D blank is removed from the mold and a subsequent drying and outgassing process is carried out at room temperature or up to 100° C. for a given time, followed by a stabilization and homogenization step at a temperature of 140° C. up to 450° C., followed by carbonization or graphitization of the 3D blank in a furnace under a protective gas atmosphere to produce a 3D object, wherein the temperature required for carbonization or graphitization is approached with a heating rate of 1° C. / min and then a temperature treatment is carried out.

2. 2. The method according to claim 1, characterized in that bamboo fibres, cotton fibres, hemp fibres, sisal fibres or graphite fibres are mixed into the material capable of being carbonised or graphitised whilst maintaining kneadability.

3. 3. The method according to claim 1 or 2, characterized in that the shaping of the 3D blank is carried out by hand and / or using a template.

4. 4. The method of claim 3, wherein stabilization and homogenization of the 3D blank occurs during heating of the furnace.

5. 5. The method according to any one of claims 1 to 4, characterized in that the 3D moulding is carbonised under vacuum or protective gas at a constant temperature of 1,000°C until pure carbon with various crystal structures is produced to form the 3D object.

6. 6. The method according to any one of claims 1 to 5, characterized in that the 3D moulding is graphitized in a furnace under vacuum or protective gas at a constant temperature of 2,000°C or higher to form a 3D object.

7. 7. The method of claim 6, characterized in that the 3D moulding is fully graphitized in a furnace under vacuum or protective gas at a temperature above 2,500° C. to form the 3D object.

8. 8. The method according to claim 1, wherein argon or helium is used as protective gas.

9. 9. The method according to claim 7 or 8, characterized in that the graphitization of the 3D part is followed by a temperature treatment lasting from about 30 minutes to several hours, using a heating rate of about 1° C. / min until the target temperature is reached.

10. 10. The method according to claim 1, characterized in that the kneadable compound is mixed with metal or silicon powder, so that high-temperature treatment of the 3D blank in a furnace under protective gas at temperatures >1,000 ° C. produces a 3D moulded part made of metal carbide or silicon carbide.

11. 11. The method according to claim 1, characterized in that the graphitized foam 3D object is converted into a 3D object made of SiC in a furnace at a temperature of >1,200° C. and a pressure of 30 mbar while supplying gaseous SiO with argon as carrier gas.