Crucible inner cover for graphitization and crucible including the same

Abstract

An inner cover for a graphitization crucible according to one embodiment of the present invention is disposed within a crucible filled with a graphitization raw material and includes a cover member disposed above the raw material and a coupling member coupled to the outer periphery of the cover member and fixed to maintain the size of the cover member during the graphitization process, wherein the coupling member includes a first coupling member and a second coupling member interlocking with each other with the outer periphery of the cover member in between.

Description

Technology Field

[0001] The present invention relates to an inner cover for a graphitizing crucible and a crucible including the same. Background Technology

[0002] Artificial graphite is widely used in fields such as negative electrode materials for secondary batteries, electrode rods for iron and steelmaking, electrodes for electrical discharge machining, nuclear fusion reactors, semiconductors, and solar cells.

[0003] Although such artificial graphite has the disadvantages of a lower degree of graphitization and a higher price due to manufacturing process costs compared to natural graphite, it is gaining attention as an anode material for secondary batteries due to its relatively superior lifespan characteristics.

[0004] Generally, artificial graphite is produced by placing a crucible filled with raw materials for artificial graphite production inside a graphitization furnace, filling the space between them with a filler so that the crucible is buried, and then indirectly heating the crucible with the resistance heat generated therefrom by passing an electric current to graphitize the raw materials inside the crucible.

[0005] At this time, a cover is placed on top of the graphitization raw material to separate the graphitization raw material and the filler, and after the graphitization process is completed, the filler present on top of the cover and foreign substances generated during the graphitization process are removed together with the cover. However, since the process temperature of the graphitization furnace is 2,000°C or higher, the cover shrinks during the graphitization process, and there is a problem in that foreign substances and filler are not separated from the raw material after the graphitization process. The problem to be solved

[0006] The technical problem that the present invention aims to solve is to enable foreign substances and fillers to be easily separated from the raw material after graphitization treatment.

[0007] However, the problems that the embodiments of the present invention aim to solve are not limited to the problems described above and can be expanded in various ways within the scope of the technical ideas included in the present invention. means of solving the problem

[0008] An inner cover for a graphitization crucible according to one embodiment is disposed within a crucible filled with a graphitization raw material and includes a cover member disposed above the raw material and a coupling member coupled to the outer periphery of the cover member and fixed to maintain the size of the cover member during the graphitization process, wherein the coupling member includes a first coupling member and a second coupling member interlocking with each other with the outer periphery of the cover member in between.

[0009] The first coupling member can be inserted into the second coupling member.

[0010] The outer diameter of the first connecting member may be smaller than the inner diameter of the second connecting member.

[0011] The above-mentioned connecting member may be in the shape of a ring.

[0012] The above-mentioned bonding member may be a carbon-based material.

[0013] The above-mentioned cover member may be a carbon-based porous sheet.

[0014] The first coupling member may have a coupling projection formed on its outer side, and the second coupling member may have a coupling groove formed on its inner side.

[0015] The second coupling member may include a wall portion to which the outer surface of the first coupling member is coupled, and a flat portion extending toward the center from the bottom of the wall portion to which the lower surface of the first coupling member is coupled.

[0016] The above wall portion may have a coupling groove formed on the inner side, and the first coupling member may have a coupling projection formed on the outer side.

[0017] A graphitization crucible according to one embodiment comprises a main body filled with a graphitization raw material, an outer cover covering the upper part of the main body, and an inner cover disposed within the main body and covering the upper part of the raw material, wherein the inner cover comprises a cover member disposed on the upper part of the raw material and a coupling member coupled to the outer periphery of the cover member and fixed to maintain the size of the cover member during the graphitization process, and wherein the coupling member comprises a first coupling member and a second coupling member interlocking with each other with the outer periphery of the cover member in between.

[0018] The outer diameter of the first connecting member may be smaller than the inner diameter of the second connecting member.

[0019] The above-mentioned connecting member is ring-shaped, and the above-mentioned covering member may be mesh-shaped.

[0020] The above-mentioned cover member is a carbon-based porous sheet, and the above-mentioned bonding member may be a carbon-based material.

[0021] The first coupling member may have a coupling projection formed on its outer side, and the second coupling member may have a coupling groove formed on its inner side.

[0022] The second coupling member may include a wall portion to which the outer surface of the first coupling member is coupled, and a flat portion extending toward the center from the bottom of the wall portion to which the lower surface of the first coupling member is coupled.

[0023] The above wall portion may have a coupling groove formed on the inner side, and the first coupling member may have a coupling projection formed on the outer side. Effects of the invention

[0024] According to an embodiment of the inner cover of a graphitization crucible and a crucible including the same, foreign substances and fillers can be easily separated from the raw material after graphitization treatment, thereby improving the work efficiency of the graphitization furnace.

[0025] However, it is evident that the effects of the embodiments are not limited to the effects described above and can be extended in various ways without departing from the spirit and scope of the present invention. Brief explanation of the drawing

[0026] FIG. 1 is an exploded perspective view of an inner cover for a graphitizing crucible according to one embodiment of the present invention and a crucible including the same. FIG. 2 is a cross-sectional view of an inner cover for a graphitizing crucible according to one embodiment of the present invention and a crucible including the same. FIG. 3 is an exploded perspective view of an inner cover of a graphitization crucible according to one embodiment of the present invention. FIG. 4 is a cross-sectional view of an inner cover of a graphitization crucible according to one embodiment of the present invention. FIG. 5 is a drawing showing the combined state of an inner cover for a graphitization crucible according to another embodiment of the present invention. FIG. 6 is an exploded perspective view of an inner cover of a graphitization crucible according to another embodiment of the present invention. Figure 7 is a diagram showing the combined state of the inner cover of the graphitization crucible of Figure 6. FIG. 8 is a drawing showing the combined state of an inner cover for a graphitization crucible according to another embodiment of the present invention. Specific details for implementing the invention

[0027] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings so that those skilled in the art can easily implement the invention. In order to clearly explain the invention in the drawings, parts unrelated to the explanation have been omitted, and the same reference numerals have been used for identical or similar components throughout the specification. Furthermore, in the attached drawings, some components may be exaggerated, omitted, or schematically depicted, and the size of each component does not entirely reflect its actual size.

[0028] The attached drawings are intended only to facilitate understanding of the embodiments disclosed in this specification, and the technical concept disclosed in this specification is not limited by the attached drawings; it should be understood that all modifications, equivalents, and substitutions included within the concept and technical scope of the present invention are included.

[0029] Terms including ordinal numbers, such as first, second, etc., may be used to describe various components, but said components are not limited by said terms. These terms are used solely for the purpose of distinguishing one component from another.

[0030] Furthermore, when it is said that a part, such as a layer, membrane, region, or plate, is "on" or "on" another part, this includes not only the case where it is "directly above" the other part, but also the case where there is another part in between. Conversely, when it is said that a part is "directly above" another part, it means that there is no other part in between. Also, saying that a part is "on" or "on" a reference part means that it is located above or below the reference part, and does not necessarily mean that it is located "on" or "on" in the direction opposite to gravity.

[0031] Throughout the specification, terms such as “comprising” or “having” are intended to indicate the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof. Accordingly, when a part is said to “comprising” a certain component, unless specifically stated otherwise, this means that it may include additional components rather than excluding other components.

[0032] Additionally, throughout the specification, "planar" means when the subject part is viewed from above, and "cross-sectional" means when the cross-section obtained by vertically cutting the subject part is viewed from the side.

[0033] Throughout the specification, when a part is described as being "coupled" with another part, this includes not only cases where they are "directly or physically coupled," but also cases where they are "indirectly or non-contact coupled" with another element in between.

[0034] In addition, throughout the specification, when the term “connected” is used, it does not mean only that two or more components are directly connected, but that two or more components are indirectly connected through other components, that they are physically connected as well as electrically connected, or that they are a single unit referred to by different names depending on their location or function.

[0035] FIG. 1 is an exploded perspective view of an inner cover for a graphitization crucible and a crucible including the same according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of an inner cover for a graphitization crucible and a crucible including the same according to an embodiment of the present invention, FIG. 3 is an exploded perspective view of an inner cover for a graphitization crucible according to an embodiment of the present invention, and FIG. 4 is a cross-sectional view of an inner cover for a graphitization crucible according to an embodiment of the present invention. Hereinafter, the detailed configuration of an inner cover for a graphitization crucible and a crucible including the same according to an embodiment will be described with reference to FIG. 1 to 4.

[0036] Referring to FIGS. 1 and 2, a graphitizing crucible (100) according to one embodiment of the present invention includes a main body (110) filled with a graphitizing raw material (C) inside, an inner cover (130) covering the upper part of the raw material inside the main body (110), and an outer cover (150) covering the upper part of the main body (110).

[0037] The main body (110) may be in the shape of a cylinder with an open top and may be made of a material capable of withstanding a temperature of approximately 2000°C to 3000°C, for example, graphite. The interior of the main body (110) is filled with carbon powder, which is a graphitization raw material (C), and a graphitization promoter. The graphitization promoter is a material that promotes the graphitization of carbon powder and improves performance, and may be a metal oxide.

[0038] The inner cover (130) is placed inside the main body (110) and is positioned to cover the top of the graphitization raw material (C) to prevent scattering of the graphitization raw material (C). During the graphitization process, the expansion of air remaining between the carbon powders, which are the graphitization raw material (C), and the heat convection phenomenon occurring inside the main body (110) cause the carbon powder to flow, and the carbon powder and metal oxides are scattered outside the main body (110). Therefore, by placing the inner cover (130) on the top of the graphitization raw material (C), scattering of the graphitization raw material (C) can be prevented during the graphitization process. A filler material (I) is filled into the top of the inner cover (130). The filler material (I) serves as an insulating material, and carbon black may be used.

[0039] Referring to FIG. 3, the inner cover (130) includes a cover member (131) placed on top of the graphitized raw material (C) and a connecting member (132) connected to the outer periphery of the cover member (131).

[0040] The cover member (131) may be made of a material having fine pores to facilitate the discharge of gases such as carbon dioxide and foreign substances generated during the graphitization process. For example, the cover member (131) may be in the form of a mesh and may be made of a carbon-based porous sheet such as graphite felt or carbon fabric. The graphite felt may be any one of pitch-based graphite felt, polyacrylonitrile-based (PAN-based) graphite felt, or viscose-based graphite felt.

[0041] The connecting member (132) is a member that fixes the cover member (131) to maintain its size during the graphitization process and includes a first connecting member (1321) and a second connecting member (1322) that interlock with each other with the outer periphery of the cover member (131) in between. The connecting member (132) may be ring-shaped and may be made of a carbon-based material such as graphite or a carbon block.

[0042] Referring to FIG. 4, the first coupling member (1321) and the second coupling member (1322) can be coupled so as to interlock with each other with the outer periphery of the cover member (131) in between. The outer diameter of the first coupling member (1321) is formed to be equal to or smaller than the inner diameter of the second coupling member (1322) so that the first coupling member (1321) can be inserted into the second coupling member (1322) and coupled. The outer diameter of the second coupling member (1322) may be equal to the inner diameter of the main body (110) so that the inner cover (130) completely covers the upper part of the graphitized raw material (C).

[0043] As illustrated in FIG. 4(a), a cover member (131) is placed on the upper side of a second connecting member (1322), and a first connecting member (1321) is placed on the upper side of the cover member (131). Then, the first connecting member (1321) can be fitted into the inner side of the second connecting member (1322) to be connected. At this time, in order for the first connecting member (1321) and the second connecting member (1322) to securely fix the cover member (131), it is preferable that the outer diameter of the first connecting member (1321) be equal to the inner diameter of the second connecting member (1322), or if smaller, be smaller than the thickness of the cover member (131).

[0044] Referring to FIG. 4(b), the outer surface of the first coupling member (1321) and the inner surface of the second coupling member (1322) face each other, and the outer periphery of the cover member (131) is positioned between the outer surface of the first coupling member (1321) and the inner surface of the second coupling member (1322). In this way, since the cover member (131) is fixed by the interlocking coupling of the first coupling member (1321) and the second coupling member (1322), the cover member (131) does not shrink even at a temperature of 2000°C to 3000°C during the graphitization process, so the graphitization raw material (C), the filler, and foreign substances can be reliably separated. Therefore, the filler present on the upper part of the inner cover (130) after the graphitization process and foreign substances generated during the graphitization process can be easily removed from the crucible (100).

[0045] The outer cover (150) covers the upper opening of the main body (110) and closes the main body (110) filled with graphitization raw material (C). The outer cover (150) may have at least one pore (not shown) formed through the upper and lower parts of the outer cover (150) so that gases such as carbon dioxide generated during the graphitization process can be discharged.

[0046] The outer cover (150) may have a cover plate (151) having an outer diameter equal to the outer diameter of the main body (110), and an extension part (152) extending from the cover plate (151) into the interior of the main body (110). The extension part (152) may have an outer diameter equal to the inner diameter of the main body (110). The outer cover (150) may be coupled to the main body (110) through the extension part (152), and may be screw-coupled to the main body (110) by forming screw threads on the outer surface of the extension part (152), or may be fitted-coupled to the inner surface of the main body (110).

[0047] FIG. 5 is a drawing showing the combined state of an inner cover for a graphitization crucible according to another embodiment of the present invention.

[0048] Referring to FIG. 5, the inner cover of the graphitization crucible according to the present embodiment has a configuration generally identical to that of the embodiment described with reference to FIG. 1 to 4. However, in the present embodiment, the structure of the connecting member may be configured differently. Below, configurations that differ are described, and identical configurations are denoted by the same reference numerals. Configurations not separately described may be configured in the same way as the embodiments shown in FIG. 1 to 4.

[0049] The inner cover (130) of the graphitization crucible according to the present embodiment includes a cover member (131) placed on top of the graphitization raw material (C) and a connecting member (132) connected to the outer periphery of the cover member (131).

[0050] The cover member (131) may be made of a material having fine pores to facilitate the discharge of gases such as carbon dioxide and foreign substances generated during the graphitization process. For example, the cover member (131) may be in the form of a mesh and may be made of a carbon-based porous sheet such as graphite felt or carbon fabric.

[0051] The connecting member (132) is a member that fixes the cover member (131) to maintain its size during the graphitization process and includes a first connecting member (1321) and a second connecting member (1322) that interlock with each other with the outer periphery of the cover member (131) in between. The connecting member (132) may be ring-shaped and may be made of a carbon-based material such as graphite or a carbon block.

[0052] Referring to FIG. 5, the first coupling member (1321) has a coupling projection (132a) formed on its outer side, and the second coupling member (1322) has a coupling groove (132b) formed on its inner side. The outer diameter of the coupling projection (132a) is formed to be smaller than the inner diameter of the coupling groove (132b) so that they can be coupled to interlock with each other with the outer periphery of the cover member (131) in between.

[0053] As illustrated in FIG. 5(a), a cover member (131) is placed on the upper part of the second coupling member (1322), and the first coupling member (1321) is placed on the upper part of the cover member (131). Then, the coupling projection (132a) of the first coupling member (1321) can be fitted into the coupling groove (132b) of the second coupling member (1322) to form a coupling. At this time, the second coupling member (1322) is slightly opened by the force pressing the first coupling member (1321), causing the coupling projection (132a) of the first coupling member (1321) to slide into the coupling groove (132b) of the second coupling member (1322) to form a coupling. It is preferable that the protrusion height of the coupling projection (132a) and the depth of the coupling groove (132b) are within the range where the elasticity of the first coupling member (1321) is permissible.

[0054] Referring to FIG. 5(b), the coupling projection (132a) of the first coupling member (1321) and the coupling groove (132b) of the second coupling member (1322) face each other, and the outer circumference of the cover member (131) is positioned between the outer surface of the coupling projection (132a) and the inner surface of the coupling groove (132b). In this way, the cover member (131) is securely fixed by the interlocking coupling of the coupling projection (132a) of the first coupling member (1321) and the coupling groove (132b) of the second coupling member (1322), thereby reliably preventing shrinkage of the cover member (131) during the graphitization process. Therefore, the filler material present on the upper part of the inner cover (130) after the graphitization process and foreign substances generated during the graphitization process can be easily removed from the crucible (100).

[0055] FIG. 6 is an exploded perspective view of an inner cover for a graphitization crucible according to another embodiment of the present invention, and FIG. 7 is a drawing showing the assembled state of the inner cover for a graphitization crucible of FIG. 6.

[0056] Referring to FIGS. 6 and 7, the inner cover of the graphitization crucible according to the present embodiment has a configuration generally identical to that of the embodiment described with reference to FIGS. 1 to 4. However, in the present embodiment, the structure of the connecting member may be configured differently. Below, configurations that differ are described, and identical configurations are denoted by the same reference numerals. Configurations not separately described may be configured in the same way as the embodiments shown in FIGS. 1 to 4.

[0057] The inner cover (130) of the graphitization crucible according to the present embodiment includes a cover member (131) placed on top of the graphitization raw material (C) and a connecting member (132) connected to the outer periphery of the cover member (131).

[0058] The cover member (131) may be made of a material having fine pores to facilitate the discharge of gases such as carbon dioxide and foreign substances generated during the graphitization process. For example, the cover member (131) may be in the form of a mesh and may be made of a carbon-based porous sheet such as graphite felt or carbon fabric.

[0059] The connecting member (132) is a member that fixes the cover member (131) to maintain its size during the graphitization process and includes a first connecting member (1321) and a second connecting member (1322) that interlock with each other with the outer periphery of the cover member (131) in between. The connecting member (132) may be ring-shaped and may be made of a carbon-based material such as graphite or a carbon block.

[0060] Referring to FIG. 6, the second connecting member (1322) includes a wall portion (132c) to which the outer surface of the first connecting member (1321) is connected, and a flat portion (132d) to which the lower surface of the first connecting member (1321) is connected. The flat portion (132d) extends from the bottom of the wall portion (132c) toward the center, and the outer diameter of the first connecting member (1321) is formed to be equal to or smaller than the inner diameter of the wall portion (132c).

[0061] Referring to FIG. 7 (a), a cover member (131) is placed on the upper part of the second connecting member (1322), and after placing the first connecting member (1321) on the upper part of the cover member (131), the first connecting member (1321) can be fitted into the inner side of the second connecting member (1322) to be connected.

[0062] Referring to FIG. 7(b), the outer surface of the first coupling member (1321) and the wall portion (132c) of the second coupling member (1322) face each other, and the lower surface of the first coupling member (1321) and the flat portion (132d) of the second coupling member (1322) face each other. The first coupling member (1321) may have the same height as the wall portion (132c) so that the upper surface of the second coupling member (1322) and the first coupling member (1321) are placed on the same plane.

[0063] In order for the first connecting member (1321) and the second connecting member (1322) to securely fix the cover member (131), it is preferable that the outer diameter of the first connecting member (1321) be equal to the inner diameter of the wall portion (132c) of the second connecting member (1322), or if smaller, be smaller than the thickness of the cover member (131). In this way, since the cover member (131) is securely fixed by the first connecting member (1321) fitting into the wall portion (132c) and the flat portion (132d) of the second connecting member (1322), shrinkage of the cover member (131) during the graphitization process can be reliably prevented. Therefore, the filler material present on the upper part of the inner cover (130) after the graphitization process and foreign substances generated during the graphitization process can be easily removed from the crucible (100).

[0064] FIG. 8 is a drawing showing the combined state of an inner cover for a graphitization crucible according to another embodiment of the present invention.

[0065] Referring to FIG. 8, the inner cover of the graphitization crucible according to the present embodiment has a configuration generally identical to that of the embodiment described with reference to FIG. 1 to 4. However, in the present embodiment, the structure of the connecting member may be configured differently. Below, configurations that differ are described, and identical configurations are denoted by the same reference numerals. Configurations not separately described may be configured in the same way as the embodiments shown in FIG. 1 to 4.

[0066] The inner cover (130) of the graphitization crucible according to the present embodiment includes a cover member (131) placed on top of the graphitization raw material (C) and a connecting member (132) connected to the outer periphery of the cover member (131).

[0067] The cover member (131) may be made of a material having fine pores to facilitate the discharge of gases such as carbon dioxide and foreign substances generated during the graphitization process. For example, the cover member (131) may be in the form of a mesh and may be made of a carbon-based porous sheet such as graphite felt or carbon fabric.

[0068] The connecting member (132) is a member that fixes the cover member (131) to maintain its size during the graphitization process and includes a first connecting member (1321) and a second connecting member (1322) that interlock with each other with the outer periphery of the cover member (131) in between. The connecting member (132) may be ring-shaped and may be made of a carbon-based material such as graphite or a carbon block.

[0069] Referring to FIG. 8, the second coupling member (1322) includes a wall portion (132c) to which the outer surface of the first coupling member (1321) is coupled, and a flat portion (132d) that extends from the bottom of the wall portion (132c) toward the center and to which the lower surface of the first coupling member (1321) is coupled. The first coupling member (1321) has a coupling projection (132e) formed on its outer side, and the second coupling member (1322) has a coupling groove (132f) formed on the inner side of the wall portion (132c). The outer diameter of the coupling projection (132e) is formed to be smaller than the inner diameter of the coupling groove (132f) so that they can be coupled to interlock with each other with the outer periphery of the cover member (131) in between.

[0070] As illustrated in FIG. 8(a), a cover member (131) is placed on the upper part of the second coupling member (1322), and the first coupling member (1321) is placed on the upper part of the cover member (131). Then, the coupling projection (132e) of the first coupling member (1321) can be fitted into the coupling groove (132f) of the second coupling member (1322) to form a coupling. At this time, the second coupling member (1322) is slightly opened by the force pressing the first coupling member (1321), causing the coupling projection (132e) of the first coupling member (1321) to slide into the coupling groove (132f) of the second coupling member (1322) and form a coupling. It is preferable that the protrusion height of the coupling projection (132e) and the depth of the coupling groove (132f) are within the range where the elasticity of the first coupling member (1321) is permissible.

[0071] Referring to FIG. 8(b), the coupling projection (132e) of the first coupling member (1321) and the coupling groove (132f) formed in the wall portion (132c) of the second coupling member (1322) face each other, and the outer circumference of the cover member (131) is positioned between the outer surface of the coupling projection (132e) and the inner surface of the coupling groove (132f). Additionally, the lower surface of the first coupling member (1321) and the flat portion (132d) of the second coupling member (1322) face each other. The first coupling member (1321) may have the same height as the wall portion (132c) so that the upper surface of the second coupling member (1322) and the first coupling member (1321) are positioned on the same plane.

[0072] In this way, since the cover member (131) is securely fixed by the fitting connection between the coupling projection (132e) of the first coupling member (1321) and the coupling groove (132f) of the second coupling member (1322), shrinkage of the cover member (131) during the graphitization process can be reliably prevented. Therefore, the filler material present on the upper part of the inner cover (130) after the graphitization process and foreign substances generated during the graphitization process can be easily removed from the crucible (100).

[0073] Although various embodiments of the present invention have been described above, the drawings and the detailed description of the invention referenced so far are merely illustrative of the present invention and are used only for the purpose of explaining the present invention, not to limit the meaning or the scope of the present invention as defined in the claims. Therefore, those skilled in the art will understand that various modifications and equivalent alternative embodiments are possible therefrom. Accordingly, the true technical scope of protection of the present invention should be determined by the technical spirit of the appended claims. Explanation of the symbols

[0074] 100: Crucible 110: Main body 130: Inner cover 131: Cover member 132: Connecting member 1321: First connecting member 1322: Second connecting member 132a, 132e: Connecting projection 132b, 132f: Connecting grooves 132c: Wall 132d: Flat section 150: Outer cover 151: Cover plate 152: Extension part

Claims

Claim 1 An inner cover for a graphitization crucible, comprising a cover member disposed within a crucible filled with a graphitization raw material and positioned above the raw material, and a coupling member coupled to the outer periphery of the cover member and fixed to maintain the size of the cover member during the graphitization process, wherein the coupling member comprises a first coupling member and a second coupling member interlocking with each other with the outer periphery of the cover member in between, and the first coupling member being inserted into the second coupling member. Claim 2 delete Claim 3 In claim 1, an inner cover for a graphitization crucible, wherein the outer diameter of the first connecting member is smaller than the inner diameter of the second connecting member. Claim 4 In claim 1, the connecting member is a ring-shaped inner cover for a graphitization crucible. Claim 5 In claim 1, the connecting member is an inner cover for a graphitization crucible, which is a carbon-based material. Claim 6 In claim 1, the cover member is a carbon-based porous sheet, an inner cover for a graphitization crucible. Claim 7 An inner cover for a graphitization crucible according to claim 1, wherein the first coupling member has a coupling projection formed on the outer side and the second coupling member has a coupling groove formed on the inner side. Claim 8 In claim 1, the second connecting member comprises a wall portion to which the outer surface of the first connecting member is connected, and a flat portion extending toward the center from the bottom of the wall portion to which the lower surface of the first connecting member is connected, an inner cover for a graphitization crucible. Claim 9 In claim 8, the inner cover of a graphitization crucible, wherein the wall portion has a coupling groove formed on the inner side and the first coupling member has a coupling projection formed on the outer side. Claim 10 A graphitization crucible comprising a main body filled with a graphitization raw material, an outer cover covering the upper part of the main body, and an inner cover disposed within the main body and covering the upper part of the raw material, wherein the inner cover comprises a cover member disposed on the upper part of the raw material and a coupling member coupled to the outer periphery of the cover member and fixing to maintain the size of the cover member during the graphitization process, wherein the coupling member comprises a first coupling member and a second coupling member interlocking with each other with the outer periphery of the cover member in between, and wherein the first coupling member is inserted into the second coupling member. Claim 11 A graphitization crucible according to claim 10, wherein the outer diameter of the first connecting member is smaller than the inner diameter of the second connecting member. Claim 12 A graphitization crucible according to claim 10, wherein the connecting member is ring-shaped and the covering member is mesh-shaped. Claim 13 A graphitization crucible according to claim 10, wherein the cover member is a carbon-based porous sheet and the bonding member is a carbon-based material. Claim 14 A graphitization crucible according to claim 10, wherein the first coupling member has a coupling projection formed on the outer side and the second coupling member has a coupling groove formed on the inner side. Claim 15 A graphitization crucible according to claim 10, wherein the second coupling member comprises a wall portion to which the outer surface of the first coupling member is coupled, and a flat portion extending toward the center from the bottom of the wall portion to which the lower surface of the first coupling member is coupled. Claim 16 A graphitization crucible according to claim 15, wherein the wall portion has a coupling groove formed on the inner side and the first coupling member has a coupling projection formed on the outer side.

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