Method for repairing graphite crucible

Abstract

The invention provides a method for repairing a graphite crucible. The method comprises the following steps: S1, covering a to-be-repaired surface of the graphite crucible with a carbon-carbon composite material; an adhesive is arranged between the to-be-repaired surface and the carbon-carbon composite material; and S2, fixing the carbon-carbon composite material on the graphite crucible through graphite screws. According to the repairing method, assembly line operation can be formed, and the operation speed is high; the service life of the repaired graphite crucible can be prolonged by more than 2 months, so that the average service life of the graphite crucible is prolonged by more than 72.5%, and the average use cost of the graphite crucible is reduced by 50%.

Description

Technical Field

[0001] The invention relates to a method for repairing a graphite crucible. Background Art

[0002] After the graphite negative electrode material is coated with asphalt, it is filled into a graphite crucible by a filling machine. Then the graphite crucible containing the material is sent into a roller kiln (divided into a heating zone, a constant temperature zone, and a cooling zone) for sintering and carbonization. The temperature in the constant temperature zone is about 1200°C. During the carbonization process, the material undergoes physical and chemical reactions.

[0003] During the use of the above-mentioned graphite crucible, the following problems exist: 1) The graphite crucible is easily oxidized in the kiln, making the crucible prone to cracks and breakage; 2) The graphite crucible becomes brittle and easily broken in the high temperature environment of 1200°C in the kiln; 3) During the external movement of the graphite crucible, due to the action of external force, the crucible is prone to cracks, or a hole is formed in the crucible wall, or a surface is damaged.

[0004] The existing treatment scheme is usually to collect the broken crucibles and scrap them; and to use graphite high-temperature glue to bond the broken crucible pieces. This solution has the following two defects: 1) The crucibles are scrapped together, which greatly reduces the life of the crucible and increases the cost of using the crucible. At present, the unit price of the crucible is 1,400 yuan / piece, the normal life is 4 months, and the average overall life does not exceed 2 months, resulting in an average crucible cost of 300 yuan / ton in the current carbonization process of the lithium battery industry. 2) The graphite glue bonding operation is troublesome and prone to bonding dislocation. After experimental verification, it takes at least 15 minutes to complete the bonding of a crucible. And then enter the back kiln, it is more likely to crack and break at the bonding point at a high temperature of 1200 degrees. After actual verification, the bonded graphite crucible can be used for up to one week before it breaks. One hidden danger is that if the bonding point is damaged, the graphite slag can easily fall into the crucible and mix with the material, causing a quality accident. Another hidden danger is that after the bonded crucible breaks in the kiln and falls onto the stick, it is easy to affect the movement of the crucible in the kiln, causing the crucible to shift and move, which in turn leads to kiln blockage, necessitating production suspension and cooling down.

[0005] In summary, in the field of lithium battery negative electrode material manufacturing and other similar fields that use graphite crucibles for high-temperature carbonization, how to reduce the cost of using crucibles and extend the service life of crucibles has become an industry problem. Summary of the invention

[0006] In order to overcome the defects of high use cost and short service life of graphite crucible in the prior art, the present invention provides a method for repairing a graphite crucible; the repairing method of the present invention can form a pipeline operation with a fast operation speed; the service life of the repaired graphite crucible can be extended by more than 2 months, thereby extending the average service life of the graphite crucible by more than 72.5%, and reducing the average use cost of the graphite crucible by 50%.

[0007] The present invention provides a method for repairing a graphite crucible, which comprises the following steps:

[0008] S1, covering the surface to be repaired of the graphite crucible with a carbon-carbon composite material; an adhesive is provided between the surface to be repaired and the carbon-carbon composite material;

[0009] S2. The carbon-carbon composite material is fixed on the graphite crucible by graphite screws.

[0010] In the present invention, if only an adhesive is provided between the carbon-carbon composite material and the surface to be repaired of the graphite crucible, the graphite crucible obtained by this repair method will easily break at the bonding point at a high temperature of 1200°C; if the carbon-carbon composite material is only fixed to the graphite crucible by graphite screws, due to the movement, loading, pouring and other actions of the graphite crucible inside and outside the kiln, the crucible repaired by this method will inevitably cause the screws to loosen due to a certain degree of vibration, thereby affecting the repair effect of the graphite crucible.

[0011] In some embodiments, in step S1 , the carbon-carbon composite material includes a carbon-carbon plate.

[0012] In a specific embodiment, the material of the carbon-carbon plate includes carbon fiber and / or resin; wherein the resin may be epoxy resin or the like.

[0013] In a certain embodiment, the carbon-carbon plate is composited by carbon fiber and resin, and has the characteristics of high temperature resistance, good wear resistance, lightness and strength; wherein, carbon fiber has the characteristics of light weight, high performance, high stiffness, high strength, excellent mechanical properties and excellent electromagnetic properties; resin has relatively low strength and stiffness, and is easily impacted and damaged. The carbon-carbon plate composited by carbon fiber and resin can make up for the disadvantages of the resin itself.

[0014] In some embodiments, the carbon-carbon plate has a thickness of 3-5 mm; the carbon-carbon plate has the characteristics of high temperature resistance, wear resistance, lightness and strength; within the above thickness range, its strength and crucible life are not affected.

[0015] In some embodiments, in step S1, the adhesive coating thickness is 1-2 mm; when the adhesive is coated on the bonding interface of the carbon-carbon composite material, the adhesive coating thickness is 2 mm; when the adhesive is coated on the crack gap of the graphite crucible, the adhesive coating thickness is 1 mm.

[0016] In some embodiments, in step S1, the adhesive includes a high temperature resistant graphite adhesive, such as ZS-1052 graphite antioxidant or RLHY-305 graphite antioxidant coating.

[0017] In a preferred embodiment, the high temperature resistant graphite adhesive has a tolerance temperature of 1200°C.

[0018] In some embodiments, in step S1, the cutting size of the carbon-carbon composite material is the same as the size of the surface to be repaired.

[0019] In step S2 of the present invention, the fixing method is a screw connection method, which has good compatibility; and the fixing method uses a graphite screw, which is the same substance in a different form as the material (lithium battery negative electrode material graphite powder) subsequently loaded into the graphite crucible, thereby avoiding the use of conventional metal screws, which may become loose and mixed into the material, causing major quality accidents.

[0020] In some embodiments, in step S2, the specification of the graphite screw is M5-M10.

[0021] In a preferred embodiment, the specification of the graphite screw is M8.

[0022] In some embodiments, in step S2, the graphite screw comprises a countersunk graphite screw.

[0023] In some embodiments, in step S2, the adhesive of step S1 is coated on the thread of the graphite screw so that the graphite screw can be firmly connected to avoid the graphite screw from loosening when the graphite crucible vibrates.

[0024] In some embodiments, before the fixing, the carbon-carbon composite material and the surface to be repaired are respectively punched; preferably, before the punching, the fixing position of the graphite screw is marked.

[0025] In a specific implementation, the drilling method includes: first drilling with a bench drill, and then making tapping threads with a tapping machine.

[0026] In a preferred embodiment, the specification of the tapping drill bit of the tapping machine is the same as that of the graphite screw.

[0027] In a preferred embodiment, the specification of the bench drill is M7.

[0028] In a preferred embodiment, the specification of the tapping drill bit of the tapping machine is the same as that of the graphite screw, for example, M8.

[0029] In some embodiments, the fixing operation further includes solidification and standing for 2 minutes to make the bonded objects more firmly.

[0030] In some embodiments, after the fixing operation, the protruding end of the graphite screw is ground flat; preferably, the grinding tool is a hand grinder.

[0031] In some embodiments, after the fixing operation, a graphite antioxidant is sprayed on the outer surface of the graphite crucible; the carbon-carbon composite material has the characteristics of high temperature resistance, wear resistance, and corrosion resistance. By performing an antioxidant treatment on the outer surface of the graphite crucible, the oxidation resistance of the graphite crucible can be further enhanced, and its wear can be slowed down. After repair, it is more solid and durable, and its life is extended.

[0032] In the present invention, the graphite crucible may be a square graphite crucible or other types of square crucibles.

[0033] In the present invention, the repair method can be applied to the carbonization production process of lithium battery negative electrode materials, and can also be used in other industries that require the use of graphite square crucibles for carbonization, which can greatly extend the service life of the graphite crucibles.

[0034] In the present invention, the repair method can be used in crucibles made of other materials, such as corundum crucibles, mullite crucibles and ceramic crucibles; when repairing crucibles made of the above materials, it is necessary to replace bonding materials, screws and adhesives.

[0035] On the basis of being in accordance with the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0036] The reagents and raw materials used in the present invention are commercially available.

[0037] The positive and progressive effects of the present invention are:

[0038] 1. The method of the present invention can form a streamlined operation, which is simple, convenient and fast. Generally, the time from completing the repair to transporting to the production line for loading and then entering the kiln for sintering is generally more than 10 minutes. It is easy to promote and has a very low investment cost.

[0039] 2. The normal service life of a graphite crucible is 4 months. After adopting the method of the present application, the repaired graphite crucible is strong and durable, and the service life of the graphite crucible can be extended by more than 2 months, thereby extending the average service life of the graphite crucible by more than 72.5%, and reducing the average use cost of the graphite crucible by 50%. DETAILED DESCRIPTION

[0040] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0041] The adhesive used in the embodiment is one of ZS-1052 graphite antioxidant (Zhisheng Huawei) and RLHY-305 graphite anti-oxidation coating (produced by Beijing Rongli Hengye Technology Co., Ltd.); the temperature resistance of these two adhesives is 1200°C.

[0042] Example 1

[0043] This embodiment discloses a method for repairing a graphite crucible, which comprises the following steps:

[0044] S1, covering one side of the carbon-carbon composite material coated with an adhesive on the surface to be repaired of the graphite crucible;

[0045] S2. The carbon-carbon composite material is fixed on the graphite crucible by graphite screws.

[0046] In step S1, the carbon-carbon composite material is a carbon-carbon plate made of carbon fiber resin with a thickness of 5 mm, and the length and width of the carbon-carbon plate are cut according to the area of ​​the crucible to be repaired.

[0047] In step S1, the adhesive is applied to the broken part of the graphite crucible, and the coating thickness of the adhesive is 1 mm. Then, the carbon-carbon plate is covered thereon and left to stand for 2 minutes.

[0048] In step S2, before the fixing operation, the points where screws are required to be fixed are first determined and marked, and holes are drilled in the carbon-carbon plate and the graphite crucible using a bench drill with an M7 drill bit, and then a tapping machine with an M8 tapping drill bit is used to make tapped threads.

[0049] In step S2, the specification of the graphite screw is M8; the thread of the graphite screw is coated with an adhesive, and after the carbon-carbon plate and the graphite crucible are screwed and fixed, a hand grinder is used to grind the raised end of the graphite screw; and then a graphite antioxidant is sprayed on the outer surface of the graphite crucible.

[0050] The method of this embodiment can form a streamlined operation, which is simple, convenient and fast. Generally, the time from completing the repair to transporting to the production line for loading operations and then entering the kiln to start sintering is generally more than 10 minutes. It is easy to promote and has a very low investment cost.

[0051] Effect Example 1

[0052] A batch of 100 graphite crucibles were repaired using the repair method of Example 1. Generally speaking, the normal life of a graphite crucible is 4 months; the service life of a graphite crucible repaired using the above method can be extended by 4 months at most, 2 months at the shortest, and 3 months on average;

[0053] It is calculated that this repair method can extend the life of the graphite crucible by 75% and reduce the average use cost of the graphite crucible by 50% to 150 yuan / ton.

[0054] Effect Example 2

[0055] A batch of 1000 graphite crucibles were repaired using the repair method of Example 1. Of the graphite crucibles repaired using the above method, 675 had their life extended by more than 4 months, 216 had their life extended by 3-4 months, and 109 had their life extended by 2-3 months.

[0056] According to the data from this batch, 89.1% of the repaired crucibles have a service life of more than 3 months (i.e., more than 75% of the normal service life), and the use cost is reduced by at least 65%; 10.9% of the repaired crucibles have a service life of 2-3 months (i.e., more than 50% of the normal service life), and the use cost is reduced by at least 50%. A comprehensive analysis of the 1,000 repaired crucibles shows that this repair method can extend the life of graphite crucibles by an average of 72.5%, and reduce the average use cost of graphite crucibles by 65% ​​to 105 yuan / ton.

Claims

1. A method for repairing a graphite crucible, characterized in that: It includes the following steps: S1, covering the surface to be repaired of the graphite crucible with a carbon-carbon composite material; an adhesive is provided between the surface to be repaired and the carbon-carbon composite material; S2. The carbon-carbon composite material is fixed on the graphite crucible by graphite screws.

2. The method for repairing a graphite crucible according to claim 1, characterized in that: In step S1, the carbon-carbon composite material includes a carbon-carbon plate; Preferably, the material of the carbon-carbon plate includes carbon fiber and / or resin; Preferably, the carbon-carbon plate has a thickness of 3-5 mm.

3. The method for repairing a graphite crucible according to claim 1, characterized in that: In step S1, the adhesive is applied with a thickness of 1-2 mm; and / or, the adhesive comprises a high temperature resistant graphite adhesive; Preferably, the high temperature resistant graphite adhesive has a tolerance temperature of 1200°C; Preferably, the adhesive is ZS-1052 graphite antioxidant or RLHY-305 graphite anti-oxidation coating.

4. The method for repairing a graphite crucible according to claim 1, characterized in that: In step S1, the cutting size of the carbon-carbon composite material is the same as the size of the surface to be repaired.

5. The method for repairing a graphite crucible according to claim 1, characterized in that: In step S2, the specification of the graphite screw is M5-M10; And / or, the graphite screw comprises a countersunk graphite screw; And / or, the thread of the graphite screw is coated with the adhesive of step S1.

6. The method for repairing a graphite crucible according to claim 5, characterized in that: The specification of the graphite screw is M8.

7. The method for repairing a graphite crucible according to claim 1, characterized in that: Before the fixing operation, the carbon-carbon composite material and the surface to be repaired are respectively punched.

8. The method for repairing a graphite crucible according to claim 7, characterized in that: The drilling method includes: first drilling with a bench drill, and then making tapping threads with a tapping machine; Preferably, the specifications of the tapping drill bit of the tapping machine are the same as those of the graphite screw; Preferably, the drill bit specification on the bench drill is M7; Preferably, the specification of the tapping drill bit of the tapping machine is the same as that of the graphite screw.

9. The method for repairing a graphite crucible according to claim 1, characterized in that: After the fixing operation, the protruding end of the graphite screw is ground flat; preferably, the grinding tool is a hand grinder.

10. The method for repairing a graphite crucible according to claim 1, characterized in that: After the fixing operation, a graphite antioxidant is sprayed on the outer surface of the graphite crucible.