A repairing agent and repairing method for graphite crucible

Abstract

The present invention discloses a repairing agent and a repairing method for a graphite crucible, wherein the repairing agent is a two-component repairing agent, including an interface repairing agent and a surface layer repairing agent; the interface repairing agent is prepared with graphite powder, paraffin oil, asphalt powder, pyridine, and SiC-Y2O3 slurry as raw materials; the surface layer repairing agent is prepared with petroleum coke powder, graphite powder, asphalt powder, and resin material as raw materials; and the corresponding graphite crucible repairing method uses the repairing agent as a tool to repair the damaged area of ​​the damaged graphite crucible. When repairing, the damaged area of ​​the damaged graphite crucible is first coated with the interface repairing agent, and after coating, it is covered with aluminum foil and wrapped with glass fiber mesh for pre-curing treatment, and then the surface layer repairing paste is used to finally complete the repair operation of the graphite crucible. The repairing agent and the repairing method of the present invention have a better repairing effect on repairing the damaged graphite crucible, and can be used to extend the service life of the damaged graphite crucible.

Description

Technical Field

[0001] The present invention relates to the technical field of graphite crucibles, and in particular to a repairing agent and a repairing method for graphite crucibles. Background Art

[0002] Graphite materials offer excellent properties such as a low thermal expansion coefficient, high-temperature resistance, electrical and thermal conductivity, stable chemical properties, and superior high-temperature mechanical properties. They are widely used in high-temperature fields such as aerospace, electronics, and machinery. Graphite crucibles, a type of crucible made from graphite, exhibit excellent thermal conductivity and high-temperature resistance. During high-temperature use, they exhibit a low thermal expansion coefficient and are highly resistant to rapid heating and cooling, as well as acidic and alkaline environments, making them suitable for casting in a variety of molds. Consequently, graphite crucibles are widely used in the smelting of alloy tool steels and the melting of non-ferrous metals and their alloys.

[0003] There are two main types of damage to graphite crucibles during actual use. One is the damage caused by external forces during loading, unloading, transportation, and storage. In addition, graphite materials also have their own material defects. They are prone to oxidation in high temperature and oxidizing atmosphere environments. The higher the temperature, the faster the oxidation rate. Continuous use in high temperature environments will cause internal oxidation and reduce its strength, resulting in a loose internal structure, which in turn causes cracks or damage to the graphite crucible. Under traditional technical conditions, cracked or damaged graphite crucibles cannot be used anymore and are usually scrapped and replaced with new crucibles. This results in high costs for the use of graphite crucibles, which account for a considerable proportion of production costs.

[0004] Based on the above reasons, in order to increase the number of uses of graphite crucibles, repairing cracked or damaged parts of graphite crucibles to recycle graphite parts is an important means to increase the life of graphite crucibles and is of great significance for reducing production costs. At present, graphite crucibles are mainly repaired with special graphite crucible repair pastes. As a special paste-like adhesive, it is mainly made of graphite powder as a matrix, modified resin and other additives. It has excellent high temperature resistance, adhesion and chemical stability, and can provide effective repair protection for damaged parts of graphite crucibles under high temperature, high pressure or corrosive environments. However, existing graphite crucible repair pastes generally have the defect of low repair strength, and the bonding between graphite crucible repair paste and graphite crucible is poor. The surface is prone to collapse after molding, resulting in unsatisfactory repair effect. The structural stability of the repaired position also has certain strength defects, which can easily lead to secondary damage very quickly after use, affecting its reuse. Summary of the Invention

[0005] The technical problem solved by the present invention is to provide a repairing agent and a repairing method for a graphite crucible, which can be used to solve the defects in the above technical background.

[0006] The present invention first provides a repairing agent for a graphite crucible, which is a two-component repairing agent, including an interface repairing agent and a surface layer repairing agent;

[0007] The interface repair agent includes the following components in parts by mass:

[0008] Graphite powder: 45-55 parts, paraffin oil: 10-15 parts, asphalt powder: 10-15 parts, pyridine: 3-5 parts, SiC-Y2O3 slurry: 2-3 parts;

[0009] The SiC-Y2O3 slurry is prepared by dissolving 25 to 35 parts of SiC, 2 to 5 parts of Y2O3, and 30 to 40 parts of a resin material in 40 to 70 parts of an organic solvent, and then uniformly dispersing the mixture through ultrasonication and magnetic stirring.

[0010] The surface layer repair agent includes the following components in parts by mass:

[0011] Petroleum coke powder: 35-45 parts, graphite powder: 15-20 parts, asphalt powder: 8-10 parts, resin material 20-30 parts; the particle size of the petroleum coke powder is less than 1 mm, and the mass proportion of the petroleum coke powder with a particle size of less than 0.6 mm is 70-80%, and the mass proportion of the petroleum coke powder with a particle size of less than 0.2 mm is 30-40%.

[0012] As a further limitation, the resin material used in the SiC-Y2O3 slurry is phenolic resin or epoxy resin.

[0013] As a further limitation, the resin material used in the surface layer repair agent is one or a combination of polyethylene resin, polyvinyl alcohol resin, polypropylene resin, phenolic resin, and epoxy resin.

[0014] As a further limitation, the asphalt powder used in the interface repair agent and the surface layer repair agent is of the same type and batch.

[0015] The present invention also provides a method for repairing a graphite crucible, wherein the damaged graphite crucible is repaired using the above-mentioned repairing agent for the graphite crucible, and the operating steps are as follows:

[0016] S1 cleans the damaged area of ​​the damaged graphite crucible to ensure that the surface of the area to be repaired is free of oil, moisture and other impurities;

[0017] S2: mixing the solid powder components in the interface repair agent, mixing them evenly, and then mixing them with an organic solvent to prepare a medium-low viscosity paste fluid with a viscosity value between 600 and 650 Pa·s. Then, SiC-Y2O3 slurry, paraffin oil, and pyridine are added and dispersed evenly to obtain an interface repair agent slurry;

[0018] S3: applying the interface repair agent prepared in step S2 to the damaged area of ​​the damaged graphite crucible, smoothing and removing excess material after coating, covering the coated area with aluminum foil, and then wrapping the aluminum foil with glass fiber mesh to keep it tightly fitted, and then pre-curing the treated graphite crucible at a temperature of 300-500° C. for 2-3 hours;

[0019] S4 prepares the components of the surface repair agent into a surface repair paste using an organic solvent, then takes out the damaged graphite crucible, removes the glass fiber mesh and aluminum foil, and applies the surface repair paste on its surface. After the coating is completed, it is smoothed and the excess material is removed, and then maintenance is performed to complete the graphite crucible repair operation after the surface repair paste is completely cured.

[0020] As a further limitation, the damaged graphite crucible that can be repaired by the repair method is a graphite crucible with a damaged surface and no through-holes, and the width of the damaged crack on the corresponding graphite crucible does not exceed 10 mm.

[0021] As a further limitation, when performing the pre-curing treatment in step S3, the damaged graphite crucible wrapped with glass fiber mesh can be placed in a vacuum container for pre-curing treatment, the set vacuum degree in the vacuum container is -0.12 to -0.09 MPa, and the treatment time is 30 to 45 minutes.

[0022] As a further limitation, the curing in step S4 is carried out at a temperature of 90 to 120° C., and the curing time is 24 to 48 hours.

[0023] As a further limitation, the curing in step S4 is performed at room temperature, and the curing time is 5 to 7 days.

[0024] Beneficial effects: The present invention provides a repair agent for a graphite crucible, which repairs the local damaged parts of a damaged graphite crucible through a two-component structure. The interface repair agent and the surface layer repair agent of the two-component structure are both based on graphite powder, and the affinity between the components is improved by using the same type of asphalt powder and other additives. The interface repair agent establishes a stable interface structure, and then uses a surface layer repair agent with good affinity to repair the surface layer on the basis of the interface structure to obtain a stable external interface structure.

[0025] The above-mentioned repair agent combined with a specific repair method can obtain a stable repair structure at the damaged position of the graphite crucible. The repair structure has good thermal conductivity and high temperature resistance, good structural stability at high temperatures, and a small thermal expansion coefficient. It is particularly suitable for graphite crucibles in a burned state, ensuring their usability in high temperature, high pressure or corrosive environments and extending their service life. DETAILED DESCRIPTION

[0026] In order to enable those skilled in the art to better understand the solutions of the present invention and to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the technical solutions in the embodiments of the present invention are clearly and completely described below in conjunction with specific embodiments.

[0027] This embodiment is only a part of the embodiments of the present invention, and represents all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of the present invention. It should be noted that the terms in the specification, claims and following embodiments of the present invention are used to distinguish similar objects. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed.

[0028] The repair agent for graphite crucibles of this embodiment can be used to repair damaged graphite crucibles with damaged surfaces and no through holes. It has a good repair effect on surface damage with cracks no wider than 10 mm and is particularly suitable for graphite crucibles in a burned state.

[0029] The repair agent is a two-component repair agent, including an interface repair agent and a surface layer repair agent. The interface repair agent and the surface layer repair agent are prepared separately and packaged separately;

[0030] The interface repair agent includes 50 parts of graphite powder, 12 parts of paraffin oil, 13 parts of asphalt powder, 4 parts of pyridine and 2 parts of SiC-Y2O3 slurry in a mass ratio.

[0031] Among them, SiC-Y2O3 slurry is obtained by dissolving 30 parts of SiC, 3 parts of Y2O3, and 35 parts of resin in 60 parts of organic solvent, and then uniformly stirred by ultrasonic dispersion and magnetic stirring. The mass relationship of each component in the SiC-Y2O3 slurry is independent and has nothing to do with the mass relationship of the interface repair agent. The resin used in the SiC-Y2O3 slurry is phenolic resin, and the corresponding organic solvent used is petroleum ether.

[0032] The surface repair agent includes 35 to 45 parts of petroleum coke powder, 15 to 20 parts of graphite powder, 8 to 10 parts of asphalt powder, and 20 to 30 parts of resin material in proportion by mass.

[0033] Among them, petroleum coke powder is petroleum coke powder with a finer particle size obtained after ball milling and screening. The corresponding particle sizes are all below 1 mm, and the mass proportion of petroleum coke powder with a particle size below 0.6 mm is 68%, and the mass proportion of petroleum coke powder with a particle size below 0.2 mm is 36%; the resin material used in the surface repair agent is also phenolic resin.

[0034] In addition, in this embodiment, the asphalt powder used as raw materials in the interface repair agent and the surface layer repair agent is asphalt powder of the same type and the same batch.

[0035] When using the above-mentioned repair agent to repair a broken graphite crucible, proceed as follows:

[0036] First, use a cleaning agent to clean the damaged area of ​​the damaged graphite crucible to ensure that the surface of the area to be repaired is free of oil, moisture, and other impurities. If necessary, the damaged graphite crucible can also be cleaned as a whole. After cleaning, use stickers to circle the damaged area of ​​the damaged graphite crucible as the boundary of the area to be coated.

[0037] The graphite powder and asphalt powder in the interface repair agent are dry-mixed, and after mixing evenly, an appropriate amount of solvent oil is used as an organic solvent, and the dry-mixed graphite powder and asphalt powder are added thereto and mixed to form a medium-to-low viscosity paste fluid with a viscosity value between 630 Pa·s. After obtaining the above-mentioned paste fluid with stable morphology, SiC-Y2O3 slurry, paraffin oil, and pyridine are added thereto and dispersed evenly to obtain the interface repair agent slurry.

[0038] The above-mentioned interface repair agent slurry is applied to the surface of the above-mentioned area to be coated with the area circled by the sticker as the boundary. The coating is carried out continuously in multiple times until the surface defects of the corresponding area to be coated are completely covered and a flat surface is obtained. The coated surface is then smoothed and aluminum foil is pasted on the smoothed surface. The positioning sticker is then removed, and the glass fiber mesh is used to wrap the outside of the aluminum foil and keep it tightly fitted. The corresponding glass fiber mesh uses high-melting point glass fiber to avoid softening and denaturation during the subsequent pre-curing process.

[0039] The graphite crucible, treated with glass fiber mesh and aluminum foil, was placed in a heat treatment furnace and pre-cured at 400°C for 150 minutes. After the treatment, the crucible was naturally cooled in the furnace for 60 minutes before being removed, the glass fiber mesh removed, and the aluminum foil scraped off.

[0040] The components of the surface repair agent are prepared into a surface repair paste using solvent oil, and then the damaged graphite crucible that has undergone the above-mentioned treatment is taken out, and the above-mentioned surface repair paste is applied to the surface of the corresponding interface repair agent-treated area. After the coating is completed, it is smoothed and the excess material is removed, and then it is moved to a closed indoor space for static curing. After 7 days of curing, the repaired graphite crucible is obtained.

[0041] When the above-mentioned graphite crucible repair agent is used to repair the graphite crucible, the interface repair agent is first used to repair the damaged surface. During the repair, graphite powder can be used as a filler on the surface of the damaged area of ​​the graphite crucible, and asphalt can be used as a binder to fill and repair the damaged area. Paraffin oil and pyridine can be used to modify the surface of the filled area, and a transition layer composed of SiC-Y2O3 slurry can be established. The transition layer structure can reinforce the defective position. At the same time, the resin material in the SiC-Y2O3 slurry system will shrink in volume when it is decomposed at high temperature, resulting in the formation of surface micropores on the surface of the repair area of ​​the interface repair agent; such micropores are conducive to anchoring the surface repair agent during its attachment to the surface, and are stably formed and fully solidified during the curing process under static conditions, thereby improving the structural stability of the interface repair agent.

[0042] The graphite crucible after the above repair is completed can be used directly after the interface repair agent is fully solidified. When the use temperature reaches the softening point of the added asphalt powder, the asphalt further bonds the graphite powder and petroleum coke powder together, and as the use temperature increases, the volatile matter continues to overflow, and the asphalt is converted into amorphous carbon with strong adhesion and toughness. Paraffin oil and pyridine form an affinity interface in the composite system of the interface repair agent and the surface layer repair agent in the above process, thereby forming a cross-linked system with an interpenetrating polymer network structure, which can meet the strength and stability requirements of the graphite crucible under high temperature working conditions.

[0043] The above-mentioned repairing agent is combined with the above-mentioned repairing method to extend the service life of the damaged graphite crucible by 30-50%, and can be repaired repeatedly, thereby effectively reducing the use cost of the graphite crucible.

[0044] In addition, as an optional technical path, in other embodiments, the damaged graphite crucible wrapped with glass fiber mesh can be placed in a vacuum container for pre-curing treatment during the pre-curing treatment stage. This can effectively reduce the duration of the pre-curing treatment and allow the interface repair agent to penetrate deeper into the damaged position of the graphite crucible to further improve the reinforcement effect; when the damaged graphite crucible is pre-cured, the set vacuum degree in the vacuum container is -0.12 to -0.09 MPa, and the treatment time is 30 to 45 minutes.

[0045] During the curing stage, the curing temperature can be maintained at 90-120°C, which can effectively reduce the curing time and shorten the curing time to 24-48 hours, which is more efficient. However, the stability of the repaired graphite crucible is slightly worse than that of the repaired graphite crucible obtained by the static natural curing method mentioned in the above embodiment.

[0046] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and those skilled in the art can refer to the contents of this article and appropriately improve the process parameters to achieve it. It is particularly important to point out that all similar replacements and modifications are obvious to those skilled in the art, and they are all considered to be included in the present invention. The methods and applications of the present invention have been described through preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the methods and applications of this article without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.

Claims

1. A repairing agent for graphite crucible, characterized in that: The repair agent is a two-component repair agent, including an interface repair agent and a surface repair agent; The interface repair agent includes the following components in parts by mass: Graphite powder: 45-55 parts, paraffin oil: 10-15 parts, asphalt powder: 10-15 parts, pyridine: 3-5 parts, SiC-Y2O3 slurry: 2-3 parts; The SiC-Y2O3 slurry is prepared by dissolving 25-35 parts of SiC, 2-5 parts of Y2O3, and 30-40 parts of resin in 40-70 parts of an organic solvent, and then uniformly mixing the mixture by ultrasonic dispersion and magnetic stirring. The surface layer repair agent includes the following components in parts by mass: Petroleum coke powder: 35-45 parts, graphite powder: 15-20 parts, asphalt powder: 8-10 parts, resin material 20-30 parts; the particle size of the petroleum coke powder is less than 1 mm, and the mass proportion of the petroleum coke powder with a particle size of less than 0.6 mm is 70-80%, and the mass proportion of the petroleum coke powder with a particle size of less than 0.2 mm is 30-40%.

2. The repairing agent for graphite crucible according to claim 1, characterized in that The resin material used in the SiC-Y2O3 slurry is phenolic resin or epoxy resin.

3. The repairing agent for graphite crucible according to claim 1, characterized in that The resin material used in the surface layer repair agent is one or a combination of polyethylene resin, polyvinyl alcohol resin, polypropylene resin, phenolic resin and epoxy resin.

4. The repairing agent for graphite crucible according to claim 1, characterized in that The asphalt powder used in the interface repair agent and the surface layer repair agent is of the same type and batch.

5. A method for repairing a graphite crucible, characterized in that: The damaged graphite crucible is repaired using the repair agent for the graphite crucible according to any one of claims 1 to 4, and the operating steps are as follows: S1 cleans the damaged area of ​​the damaged graphite crucible to ensure that the surface of the area to be repaired is free of oil, moisture and other impurities; S2: mixing the solid powder components in the interface repair agent, mixing them evenly, and then mixing them with an organic solvent to prepare a medium-low viscosity paste fluid with a viscosity value between 600 and 650 Pa·s. Then, SiC-Y2O3 slurry, paraffin oil, and pyridine are added and dispersed evenly to obtain an interface repair agent slurry; S3: applying the interface repair agent prepared in step S2 to the damaged area of ​​the damaged graphite crucible, smoothing and removing excess material after coating, covering the coated area with aluminum foil, and then wrapping the aluminum foil with glass fiber mesh to keep it tightly fitted, and then pre-curing the treated graphite crucible at a temperature of 300-500° C. for 2-3 hours; S4 prepares the components of the surface repair agent into a surface repair paste using an organic solvent, then takes out the damaged graphite crucible, removes the glass fiber mesh and aluminum foil, and applies the surface repair paste on its surface. After the coating is completed, it is smoothed and the excess material is removed, and then maintenance is performed to complete the graphite crucible repair operation after the surface repair paste is completely cured.

6. The method for repairing a graphite crucible according to claim 5, characterized in that: The damaged graphite crucible is a graphite crucible with a damaged surface and no through-holes, and the width of the damaged crack on the corresponding graphite crucible does not exceed 10 mm.

7. The method for repairing a graphite crucible according to claim 5, characterized in that: The curing in step S4 is carried out at a temperature of 90 to 120° C. for 24 to 48 hours.

8. The method for repairing a graphite crucible according to claim 5, characterized in that: The curing in step S4 is performed at room temperature for 5 to 7 days.