An antioxidant graphitized electrode for electric furnaces and a method thereof

Abstract

The application relates to the technical field of graphitized electrodes, and discloses an oxidation-resistant graphitized electrode for electric furnaces and a method thereof. An oxygen-blocking reaction phase is arranged in a surface layer of a graphitized electrode core body and connected with a network of through holes. A heat-softened or heat-melted sealing phase is embedded in a shallow part of a hole mouth. A gap volume is reserved between the oxygen-blocking reaction phase and the heat-melted sealing phase. An outer surface of the heat-melted sealing phase is lower than an outer circumferential reference surface of a graphite framework. Graphite surfaces between adjacent hole mouths are kept exposed. During preparation, the oxygen-blocking reaction phase is formed through limited impregnation and heat treatment. Then, the circumferential continuous residues are removed and the hole mouths are re-opened. Subsequently, high-viscosity sealing slurry is pressed into the shallow part of the hole mouth, and the surface excess slurry is removed. The structure can limit the oxygen gas from invading along the hole network, promote the redistribution of the local sealing material by using the oxygen-blocking reaction product, and reduce the influence of the oxidation-resistant material on the clamping conductivity and the components in the furnace.

Description

Technical Field

[0001] This invention relates to the field of graphitized electrode technology, and more particularly to an antioxidant graphitized electrode for electric furnaces and its method. Background Technology

[0002] Graphitized electrodes possess excellent electrical conductivity, high temperature resistance, and high thermal stability, making them widely used in electric arc furnaces, submerged arc furnaces, and other high-temperature electric heating equipment. When operating inside a furnace, the sidewalls and ends of graphitized electrodes are constantly exposed to a high-temperature, oxygen-containing atmosphere, furnace gas erosion, molten slag splashing, and repeated thermal cycling. Graphite materials readily react with oxygen and are gradually consumed. Because graphitized electrodes typically contain open pores formed by aggregate particle gaps, calcination shrinkage cavities, and microcracks, some of which are interconnected and extend to the electrode surface, oxygen can enter the inner surface layer through the peripheral pores. This causes the oxidation reaction to extend from the surface to the deeper pores, leading to pore enlargement, localized erosion, and a reduction in electrode diameter, potentially exacerbating the unevenness of electrode consumption.

[0003] Existing anti-oxidation treatment methods mainly include infiltration sealing and surface coating. Infiltration sealing typically involves using low-viscosity resins, silicon-containing precursors, or inorganic impregnating solutions to penetrate the pores of the graphite surface, followed by curing or heat treatment to form a sealing material to reduce gas permeability. This method can reduce oxygen entering the electrode through the pores in the initial stage, but when the amount of sealing material is large, it may reduce the pores' buffering capacity against thermal stress and gas expansion within the pores. Furthermore, when cracks or localized detachment occur in the sealed area during thermal cycling, oxygen can still enter the pores through newly created channels, and the cured sealing material is difficult to redistribute according to the crack location.

[0004] Surface coating treatment typically involves continuously coating the outer periphery of the graphitized electrode with an antioxidant slurry containing silicon, aluminum, silicon carbide, or glass-forming components, followed by drying and curing to form a continuous antioxidant layer. This antioxidant layer reduces direct contact between oxygen and the graphite surface; however, the continuous coating is susceptible to wear, cracking, or peeling due to friction from the clamping device, furnace gas erosion, and differences in thermal expansion. Simultaneously, the non-conductive or low-conductive coating in the clamping area may increase contact resistance, affecting stable current transmission. Furthermore, as the electrode gradually descends and is consumed, detached or residual inorganic materials may enter the slag or molten steel, impacting furnace composition control. Summary of the Invention

[0005] The technical problem to be solved by the present invention is that the existing technology has the problem of difficulty in balancing the continuous anti-oxidation ability of the graphite surface mesh, the clamping conductivity and the stability of the anti-oxidation material. To this end, we propose an anti-oxidation graphitized electrode for electric furnace and its method.

[0006] To achieve the above objectives, this application adopts the following technical solution: an antioxidant graphitized electrode for electric furnaces and a method thereof, comprising: a graphitized electrode core, the graphitized electrode core comprising a graphite skeleton having a plurality of graphite micropores, at least a portion of the graphite micropores being interconnected to form a surface interconnected pore network, and orifices being formed on the outer peripheral surface of the graphite skeleton; an oxygen-barrier reaction phase being disposed within the surface interconnected pore network, the oxygen-barrier reaction phase being distributed on the inner side of the corresponding orifice and together forming an oxygen-barrier reaction layer, a molten sealing phase being embedded in the shallow part of the orifice, a plurality of molten sealing phases together forming a molten sealing layer, a void volume not completely filled by solid material being retained between the oxygen-barrier reaction phase and the corresponding molten sealing phase, the plurality of void volumes together forming a void buffer layer; the outer surface of the molten sealing phase being lower than the outer peripheral reference surface of the graphite skeleton to form a surface reserved opening at the corresponding orifice, the plurality of surface reserved openings together forming a remaining opening layer, and the graphite surface between adjacent orifices remaining exposed; The molten sealing phase is composed of a sealing material that can soften or melt when heated during electrode use. The oxygen barrier reaction phase is composed of an oxygen barrier material that can react with oxygen to form reaction products that increase in volume. When oxygen enters the corresponding void volume through the cracks or gaps of the molten sealing phase, the oxygen barrier reaction phase consumes the entering oxygen and causes the formed reaction products to expand toward the corresponding molten sealing phase, thereby pushing or supporting the softened or molten sealing phase from the inside to redistribute it toward the cracks or voids at the corresponding orifice.

[0007] Preferably, the method for creating an antioxidant graphitized electrode includes the following steps: S1. The graphitized electrode core with a graphite skeleton and a surface interconnected mesh is cleaned and dried so that the openings of the surface interconnected mesh remain open. S2. Under negative pressure, the first impregnating material is introduced into the surface interconnecting mesh, and then the free first impregnating material is discharged. The first impregnating material attached to the pore wall, pore throat and local pore cavity is cured and heat-treated to form an oxygen barrier reaction phase that can react with oxygen, and to retain pores in the surface interconnecting mesh that are not completely occupied by the oxygen barrier reaction phase. S3. Remove the continuous residue on the outer peripheral surface of the graphitized electrode core and some oxygen-barrier reaction phase in the shallow part of the orifice, so that the orifice is reopened and a filling space is formed in the shallow part of the orifice. S4. Press a second sealing slurry with a viscosity higher than that of the first impregnating material into the filling space, so that the second sealing slurry forms a molten sealing phase in the shallow part of the orifice that can be softened or melted by heat, and retains a void volume between the molten sealing phase and the corresponding oxygen barrier reaction phase; S5. Remove the second sealing slurry between adjacent orifices and above the outer peripheral reference surface of the graphite skeleton, so that the outer surface of the molten sealing phase is lower than the outer peripheral reference surface, and the graphite surface between adjacent orifices remains exposed.

[0008] Preferably, in step S1, the graphitized electrode core is rough machined on its outer diameter, and the formed threaded connection hole and axial joint end face are covered with solvent-resistant shielding; after rough machining of the outer diameter, the graphite powder and moisture near the hole are removed by vacuum dusting, dry gas blowing and heating drying in sequence.

[0009] Preferably, before introducing the first impregnation material, the open porosity, pore size distribution and gas permeability of the witness samples from the same batch as the graphitized electrode core are tested, and the effective pore range that makes the main contribution to gas transport in the surface interconnected pore network is determined based on the test results.

[0010] Preferably, in step S2, the graphitized electrode core is placed in a sealed impregnation container, the gas in the surface interconnecting mesh is first evacuated and discharged, and then the first impregnation material is introduced under negative pressure. Subsequently, normal pressure is restored or controlled pressure is applied to allow the first impregnation material to enter the surface interconnecting mesh.

[0011] Preferably, the first impregnation material includes an organosilicon precursor liquid, or a dispersion formed by a high residual carbon resin and silicon carbide particles; after curing and heat treatment, the first impregnation material forms a silicon carbide reactive phase, a silicon-oxygen-carbon ceramic phase, or a silicon carbide reactive phase with residual carbon.

[0012] Preferably, before forming the oxygen-barrier reaction phase, the graphitized electrode core is rotated along the axis, and the free first impregnation material on the outer peripheral surface and in the pores is removed by inert gas purging or vacuum extraction; then solvent removal, pre-curing and inert atmosphere pyrolysis or ceramic treatment are performed in sequence, so that the oxygen-barrier reaction phase is distributed in the surface interconnected pore network in the form of pore wall deposits, local fillers or particle aggregates.

[0013] Preferably, in step S3, the continuous residue is removed by external circular finishing, flexible brushing, or sandblasting to re-expose the orifice, and the removal depth of the continuous residue is less than the penetration depth of the first impregnating material in the graphitized electrode core, so that the oxygen-barrier reaction phase is retained inside the orifice.

[0014] Preferably, the second sealing slurry is thixotropic and includes a glass-forming component, silicon carbide powder, carbonaceous powder, and an inorganic binder; the glass-forming component forms a highly viscous softening phase at the electrode operating temperature.

[0015] Preferably, in step S4, the second sealing slurry is pressed into the shallow part of the orifice by elastic roller coating, scraping coating or flexible pressure coating; after the second sealing slurry is initially shaped, the outer peripheral surface of the graphitized electrode core is scraped back, flexibly brushed or polished, and solvent discharge, binder curing and stabilization treatment are performed in sequence to form a surface reserved opening located outside the molten sealing phase.

[0016] The technical effects and advantages of this invention are as follows: This invention involves setting an oxygen-barrier reaction phase, a void volume, and a molten sealing phase at the shallow part of the pores within the interconnected pore network on the surface of a graphitized electrode, from the inside out. The molten sealing phase first restricts the path of oxygen into the pore network; any small amount of oxygen that passes through the sealing area is then consumed by the oxygen-barrier reaction phase. Furthermore, the volume expansion of the reaction products supports and propels the softened molten sealing phase, allowing the sealing material to redistribute to local cracks or voids. This increases the likelihood of the pores maintaining a sealed state after thermal cycling, furnace gas scouring, and clamping friction. Simultaneously, the void volume is... The space provided for the expansion of gas and reaction products within the pores and the release of thermal stress helps to reduce the risk of cracking or peeling after the surface mesh is completely rigidly filled. In addition, the outer surface of the molten sealing phase is lower than the outer peripheral reference surface of the graphite skeleton, and the exposed graphite surface is retained between adjacent pores, which can reduce the direct scraping and overall loss of the sealing material, and reduce the impact of the continuous inorganic capping layer on the clamping conductivity, the consumption pattern of the working end, and the introduction of impurities into the furnace. Thus, a more reasonable balance is achieved between continuous anti-oxidation performance, structural stability, and normal conductive use of the electrode. Attached Figure Description

[0017] The disclosure of this invention is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of this invention. In the drawings, the same reference numerals are used to refer to the same parts: Figure 1 This is a schematic cross-sectional view of the anti-oxidation portion of the graphitized electrode of the present invention. Figure 2 This is a schematic cross-sectional view of the internal structure of the graphite micropores in the graphitized electrode of the present invention. Figure 3 This is a schematic diagram of the overall layered structure of the graphitized electrode of the present invention; Figure 4 This is a schematic cross-sectional view of the graphitized electrode of the present invention. Figure 5 This is a schematic flowchart of the graphitized electrode preparation method of the present invention; Figure 6 This is a SEM image of the cross-section of the graphitized electrode before processing according to the present invention; Figure 7 This is a SEM image of the graphitized electrode after the second sealing process of this invention. Figure 8 This is a cross-sectional SEM image of the present invention after thermal cycling.

[0018] Legend: 1. Graphitized electrode core; 11. Graphite skeleton; 2. Graphite micropores; 3. Oxygen barrier reaction layer; 31. Oxygen barrier reaction phase; 4. Void buffer layer; 41. Void volume; 5. Melt sealing layer; 51. Melt sealing phase; 6. Remaining opening layer; 61. Surface reserved opening. Detailed Implementation

[0019] It is readily understood that, based on the technical solution of this invention, those skilled in the art can propose various interchangeable structural methods and implementations without altering the essential spirit of the invention. Therefore, the following detailed embodiments and accompanying drawings are merely illustrative examples of the technical solution of this invention and should not be considered as the entirety of the invention or as limitations or restrictions on the technical solution of this invention.

[0020] Reference Figures 1 to 8 As shown, this embodiment provides an antioxidant graphitized electrode for electric furnaces, including a graphitized electrode core 1. The graphitized electrode core 1 includes a graphite skeleton 11, and the graphite skeleton 11 has a plurality of graphite micropores 2 inside. At least some of the graphite micropores 2 are interconnected to form a surface interconnected pore network extending from the outer peripheral surface of the graphite skeleton 11 into its interior. The specific pore size, cavity shape, and communication direction of the surface interconnected pore network are affected by the graphite aggregate particle size, binder distribution, calcination, and graphitization process. Each graphite micropore 2 can be in the form of a cavity, pore throat, fissure, or interparticle space.

[0021] Oxygen-barrier reactive phase 31 is dispersed in the surface interconnected pore network inside the pore opening, and multiple oxygen-barrier reactive phases 31 together constitute the oxygen-barrier reactive layer 3. The oxygen-barrier reactive phase 31 can adhere to the pore wall of the graphite micropores 2, can be trapped at the pore throat, or can form a particle aggregate occupying a local pore cavity. The oxygen-barrier reactive layer 3 belongs to the functional region statistically formed along the outer periphery of the graphitized electrode core 1, and is not required to form a continuous, uniformly thick annular solid layer with a clear geometric boundary.

[0022] A molten sealing phase 51 is embedded in the shallow part of each main orifice, and multiple molten sealing phases 51 together constitute a molten sealing layer 5. Each molten sealing phase 51 is constrained by the corresponding orifice wall, and no continuous inorganic film layer covering the outer surface of the graphite skeleton 11 is formed between adjacent orifices. Void volumes 41 that are not completely filled by solid material are retained between the oxygen barrier reaction phase 31 and the molten sealing phase 51, as well as inside the oxygen barrier reaction phase 31, and multiple void volumes 41 together constitute a void buffer layer 4. The void buffer layer 4 can be composed of irregular cavities, pore throats, and gaps between particles, and it is not required to form a continuous and uniformly thick air interlayer.

[0023] The outer surface of the molten sealing phase 51 is preferably lower than the outer peripheral reference surface of the graphite skeleton 11, forming a shallowly recessed surface pre-reserved opening 61 on its outer side. Multiple surface pre-reserved openings 61 together constitute the remaining opening layer 6. The surface pre-reserved openings 61 are located on the outer side of the molten sealing phase 51 and do not penetrate the molten sealing phase 51. Therefore, the molten sealing phase 51 still forms the main sealing of the openings of the corresponding graphite micropores 2. Since the molten sealing phase 51 does not protrude from the outer peripheral surface of the graphite skeleton 11, when the holder contacts the graphitized electrode core 1, it mainly acts on the exposed graphite skeleton 11, which helps to reduce the possibility of the molten sealing phase 51 being directly rubbed, scraped, and squeezed off.

[0024] Example 1: In this embodiment, a polycarbosilane precursor is used to form an oxygen-barrier reaction phase 31, and a sealing slurry composed of low-alkali calcium aluminum silicon glass, silicon carbide and graphite is used to form a molten sealing phase 51.

[0025] A graphitized electrode blank with a diameter of 350 mm and a length of 1800 mm was selected as the graphitized electrode core 1. The graphitized electrode core 1 was prepared by mixing coke aggregate and binder, followed by kneading, extrusion molding, calcination, impregnation, re-calcination, and graphitization treatment. The outer diameter of the graphitized electrode core 1 was rough-machined, leaving a machining allowance of 0.30 mm to 0.50 mm for subsequent machining. The threaded connection hole and axial joint end face were not finalized; when the threaded connection hole was already formed, a peelable xylene-resistant masking material was applied to the threaded connection hole and axial joint end face.

[0026] The roughly machined graphitized electrode core 1 is placed in a vacuum cleaning station, where graphite powder is removed from the outer surface and near the orifices using vacuum dust extraction. It is then purged with dry nitrogen gas at 0.15 MPa to 0.25 MPa. After purging, it is dried at 105°C to 115°C for 4 hours to remove moisture and adsorbed gases near the orifices. After drying, the graphitized electrode core 1 is cooled to below 40°C, and the use of oil-containing compressed air for purging is avoided.

[0027] A 30mm × 30mm × 15mm block-shaped witness sample was obtained from the same batch of graphite material. This witness sample and the graphitized electrode core 1 underwent subsequent impregnation, heat treatment, finishing, and sealing processes simultaneously. The pore size distribution and gas permeability were measured to determine the range of pores that significantly contribute to gas permeation. This measurement was used to determine the concentration of the first impregnation material and the impregnation time; it is not required that all nanoscale or submicron-scale micropores be penetrated by the impregnation material.

[0028] The first impregnation material is a 40% (w / w) polycarbosilane xylene solution, with divinylbenzene added as a crosslinking component at 8% (w / w) of the polycarbosilane mass. The apparent viscosity of the first impregnation material at 25°C is controlled between 30 mPa·s and 100 mPa·s to allow it to penetrate the surface interconnected pores while avoiding excessively deep impregnation due to excessively low viscosity.

[0029] The graphitized electrode core 1 is placed in a sealed impregnation container, and a vacuum is drawn to a gauge pressure of -0.085 MPa and maintained for 30 minutes to expel air from the surface interconnected pores. While maintaining the negative pressure, the first impregnation material is introduced, covering the outer peripheral surface of the graphitized electrode core 1 to be treated, and this state is maintained for another 30 minutes. The pressure is then slowly restored to atmospheric pressure, and nitrogen gas is introduced into the impregnation container to increase the pressure to 0.20 MPa to 0.30 MPa and maintained for 45 minutes, allowing the first impregnation material to penetrate the surface interconnected pores, which contribute significantly to gas transport.

[0030] After impregnation, the first impregnation material is discharged from the impregnation container, and the graphitized electrode core 1 is rotated around its axis at a speed of 1 to 3 r / min for 10 to 15 minutes. Simultaneously, dry nitrogen is used to purge the outer peripheral surface to remove free impregnation material that is not retained by the pore walls from the outer peripheral surface and larger pores. This drainage process ensures that the first impregnation material mainly adheres to the pore walls, pore throats, and local pores, while retaining remaining pores within the surface interconnected pore network.

[0031] After removing the shielding material from the threaded connection holes and axial joint end faces, the graphitized electrode core 1 is placed in an inert atmosphere heat treatment furnace. It is first held at 80℃ for 2 hours, then heated to 150℃ and held for 2 hours, followed by a further increase to 220℃ and a 2-hour holding period to allow xylene to be fully expelled and the polycarbosilane to undergo pre-crosslinking. The temperature is then further increased to 1000℃ under nitrogen protection at a rate of 1.5℃ / min to 3℃ / min, held for 2 hours, and then cooled with the furnace. After heat treatment, the polycarbosilane is transformed into a silicon carbide-containing ceramic phase, forming an oxygen-barrier reaction phase 31 in the form of pore wall deposits, pore throat traps, and localized cavity fillers.

[0032] In this embodiment, the first impregnation and heat treatment process is performed only once. A second low-concentration limited impregnation is only performed when the witnessed sample shows that the gas permeability is still higher than the preset process control range. This reduces the possibility that the oxygen-barrier reaction phase 31 will completely fill the surface interconnected pore network and reserves space for the subsequent formation of the void volume 41.

[0033] After the formation of the oxygen-barrier reaction phase 31, the graphitized electrode core 1 undergoes outer circumferential finishing. The amount of material removed is determined based on the statistical penetration depth of the first impregnated material measured from the cross-section of the witnessed sample. For example, when the statistical penetration depth of the oxygen-barrier reaction phase 31 is not less than 0.60 mm, 0.15 mm to 0.25 mm of material can be removed from the outer peripheral surface of the graphitized electrode core 1. Finishing is used to remove the continuous residual film on the outer periphery and part of the oxygen-barrier reaction phase 31 at the shallowest part of the orifice, and to reopen the main orifice, while ensuring that the oxygen-barrier reaction phase 31 is still retained inside the orifice.

[0034] The solid raw materials of the second sealing slurry include, by weight, 40 parts of low-alkali calcium-aluminum-silicon glass powder, 35 parts of silicon carbide fine powder, 15 parts of high-purity graphite powder, and 10 parts of alumina fine powder. The median particle size of the glass powder is 5 μm to 15 μm, the median particle size of the silicon carbide fine powder is 1 μm to 5 μm, and the median particle size of the graphite powder is 3 μm to 10 μm. The softening temperature of the glass powder is controlled at 850℃ to 950℃, so that it forms a highly viscous softened phase constrained by the pore walls after the electrode enters the furnace and is heated.

[0035] For every 100 parts of solid raw material, 25 to 35 parts of silica sol with a solid content of 30% are added, along with 0.2 to 0.5 parts of dispersant and 0.3 to 0.8 parts of rheology modifier, to form a thixotropic second sealing slurry. The low-shear apparent viscosity of the second sealing slurry at 25°C is controlled at 3 Pa·s to 8 Pa·s, which is significantly higher than that of the first impregnating material. This allows the slurry to enter the shallow part of the orifice during rolling and reduces its continued flow into the deeper part of the mesh after the pressure is removed.

[0036] The graphitized electrode core 1 is rotated around its axis at a speed of 0.5 r / min to 2 r / min. A flexible roller with a surface hardness of Shore A 40 to 60 is used to press the second sealing slurry into the shallow part of the reopened orifice. The contact pressure between the flexible roller and the outer surface of the electrode is controlled at 0.05 MPa to 0.15 MPa. This process does not involve vacuuming or applying impregnation pressure to the slurry. After the flexible roller passes the corresponding position, a flexible scraper is used to remove the surface slurry between adjacent orifices within 30 seconds, ensuring that the second sealing slurry is mainly retained in the shallow part of the orifice.

[0037] After a short period of settling to allow the slurry to initially solidify, the outer peripheral surface of the graphitized electrode core 1 is scraped and gently polished to remove the second sealing slurry that is higher than the outer peripheral reference surface of the graphite skeleton 11. The outer surface of the molten sealing phase 51 is preferably 0.05 mm to 0.20 mm lower than the outer peripheral reference surface to form a pre-reserved opening 61. Subsequently, the surface is sequentially heated to 60°C for 2 hours, 110°C for 2 hours, and 180°C for 1 hour to gradually remove moisture and allow the silica sol to gel and stabilize. The heating rate is controlled at 0.5°C to 2°C per minute to reduce the possibility of rapid gas expansion within the pores causing slurry overflow.

[0038] After the above treatment, the oxygen-barrier reaction phase 31 is located inside the orifice, and the molten sealing phase 51 is located in the shallow part of the orifice, with a void volume 41 between them consisting of natural cavities, pore throats, and intergranular gaps. After the electrode is heated in the furnace, the glass-forming components in the molten sealing phase 51 gradually enter a high-viscosity softening state. When microcracks are generated in the local molten sealing phase 51 due to thermal cycling or furnace gas action, a small amount of oxygen can enter the void volume 41 and preferentially react with the silicon carbide reaction components near the outer side. The resulting silicon oxide reaction products expand within the local cavities and provide support and compression for the softened molten sealing phase 51, which is beneficial for the redistribution of the molten sealing phase 51 towards the crack location.

[0039] Example 2: This embodiment uses a polysiloxane precursor to form a silicon-oxygen-carbon ceramic phase and a low-phosphorus, low-boron sealing slurry, which is suitable for operating conditions where the introduction of impurities into the furnace is relatively sensitive.

[0040] The roughing, shielding, dust collection, nitrogen purging, and heating drying steps of the graphitized electrode core 1 are the same as in Example 1. The first impregnation material is a thermosetting methylphenyl polysiloxane xylene solution with a polysiloxane mass fraction of 30% to 35%, and the apparent viscosity of the first impregnation material at 25°C is controlled between 20 mPa·s and 80 mPa·s.

[0041] The graphitized electrode core 1 is placed in a sealed impregnation container, and a vacuum is drawn to a gauge pressure of -0.075 MPa to -0.090 MPa. This vacuum is maintained for 20 to 30 minutes before introducing the first impregnation material. The negative pressure is maintained for another 20 minutes while the first impregnation material covers the outer peripheral surface to be treated. Then, atmospheric pressure is restored and maintained for 30 minutes. For electrodes with high open porosity, a nitrogen pressure below 0.20 MPa can be further applied and maintained for 20 minutes.

[0042] After impregnation, the graphitized electrode core 1 was rotated at 2 r / min for 10 min, and free liquid was removed by nitrogen purging. It was then held at 80℃ for 2 h and at 180℃ for 3 h to allow the polysiloxane to complete solvent removal and cross-linking curing. The cured graphitized electrode core 1 was then heated to 950℃ at a rate of 2℃ / min under a nitrogen atmosphere, held for 2 h, and then cooled in the furnace, allowing the polysiloxane to transform into an oxygen-barrier reactive phase 31 containing silicon-oxygen-carbon ceramic phase within the surface interconnected pores.

[0043] The orifice is re-exposed by removing 0.10 mm to 0.20 mm of the outer circumference material through finishing. The amount of material removed is confirmed based on witnessed samples and should be less than the statistical penetration depth of the oxygen-barrier reaction phase 31.

[0044] The second sealing slurry in this embodiment uses a material system without the active addition of phosphorus and boron. Every 100 parts by weight of solid raw materials includes 45 parts of calcium magnesium aluminum silicate glass powder, 30 parts of silicon carbide fine powder, 10 parts of high-purity graphite powder, and 15 parts of alumina fine powder. The softening temperature of the glass powder is 900℃ to 1050℃. Every 100 parts of solid raw materials, 20 to 30 parts of silica-alumina composite sol are added, along with 0.3 parts of dispersant and 0.5 parts of rheology modifier.

[0045] The second sealing slurry is pressed into the shallow part of the orifice using a short-time scraping method, with the contact time between the scraping tool and the outer peripheral surface of the graphitized electrode core 1 controlled between 2 and 8 seconds. Immediately after the second sealing slurry enters the orifice, it is scraped back to expose the graphite surface between adjacent orifices. The outer surface of the molten sealing phase 51 after scraping back is 0.03 mm to 0.15 mm lower than the outer peripheral reference surface of the graphite skeleton 11.

[0046] The mixture was then held at 50°C for 2 hours, at 100°C for 3 hours, and at 160°C for 2 hours, before being slowly cooled to room temperature. This staged curing process reduces the likelihood of the slurry surface hardening prematurely while internal moisture is concentrated and discharged, and also reduces the possibility of the molten sealing phase 51 entering the depth of the void volume 41.

[0047] The silicon-oxygen-carbon ceramic phase can locally form silicon oxide reaction products when oxygen enters, and cooperate with the high-viscosity glass seal at the shallow part of the orifice. Since no continuous inorganic covering film is formed between adjacent orifices, the outer peripheral surface of the graphite skeleton 11 can still directly contact the holder, which is beneficial to maintaining the clamping conductivity. This embodiment is mainly used to reduce the porosity expansion and local erosion caused by oxygen diffusion along the surface interconnecting mesh into the electrode.

[0048] Example 3: In this embodiment, a first impregnation material composed of a high residual carbon thermosetting resin and submicron silicon carbide particles is used to form a residual carbon-bonded silicon carbide oxygen barrier reaction phase 31.

[0049] The graphitized electrode core 1, after rough machining, vacuum dust removal, and nitrogen purging, is dried at 110℃ for 3 hours. The first impregnation material comprises, by mass percentage, 18% thermosetting phenolic resin, 12% submicron silicon carbide particles, 69.5% ethanol, and 0.5% dispersant. The median particle size of the silicon carbide particles is controlled between 0.15 μm and 0.50 μm. After high-speed dispersion and ultrasonic treatment, the apparent viscosity of the first impregnation material at 25℃ is controlled between 15 mPa·s and 60 mPa·s, and low-speed circulation is maintained during impregnation to reduce silicon carbide particle sedimentation.

[0050] The graphitized electrode core 1 is placed in a sealed impregnation container, and a vacuum is drawn to a gauge pressure of -0.090 MPa and maintained for 20 min. Then, the first impregnation material is introduced under negative pressure and maintained for 30 min. Then, the pressure is restored to normal and nitrogen pressure of 0.15 MPa to 0.25 MPa is applied and maintained for 30 min.

[0051] After the first impregnation material is discharged, the graphitized electrode core 1 is rotated at 1 to 2 r / min for 15 min, and the free dispersion in the larger pores is discharged by nitrogen purging and short-term vacuum back-extraction. After the discharge, the submicron silicon carbide particles are mainly retained in the pore throat, pore wall depressions and local pores, while the phenolic resin adheres between the silicon carbide particles and the graphite pore walls.

[0052] The graphitized electrode core 1 was sequentially heated to 80℃ for 2 hours and then to 150℃ for 3 hours to cure the phenolic resin. Subsequently, under nitrogen protection, the temperature was increased to 850℃ at a rate of 1℃ / min to 2℃ / min and held for 2 hours to carbonize the phenolic resin and form a residual carbon-bonded phase. Silicon carbide particles and the residual carbon-bonded phase together form the oxygen-barrier reaction phase 31. The silicon carbide particles serve as the main oxygen-barrier component capable of forming silicon oxide-containing reaction products, while the residual carbon-bonded phase retains the silicon carbide particles at the pore walls and throats.

[0053] Remove 0.10 mm to 0.20 mm of material from the outer peripheral surface to remove continuous residue and reopen the orifice. The solid raw materials of the second sealing slurry include, by weight, 50 parts of low-alkali aluminosilicate glass powder, 25 parts of silicon carbide fine powder, 15 parts of graphite powder, and 10 parts of alumina fine powder. For every 100 parts of solid raw materials, add 28 to 35 parts of silica sol, and add no more than 1 part of dispersant and rheology modifier.

[0054] The second sealing slurry was applied to the shallow part of the orifice using a flexible pressure coating method. Immediately after pressure coating, the slurry on the outer surface was removed using an elastic scraper, followed by flexible polishing to ensure that the outer surface of the molten sealing phase 51 was 0.05 mm to 0.20 mm lower than the outer reference surface of the graphite skeleton 11. Subsequently, drying, gelation, and stabilization were completed sequentially at 60℃, 110℃, and 180℃, with holding times of 2 h, 2 h, and 1 h for each temperature stage, respectively.

[0055] This implementation does not require silicon carbide particles to enter all the fine graphite micropores 2. By controlling the particle size, the viscosity of the first impregnation material, and the drainage intensity, the silicon carbide particles are mainly distributed in the pore walls, throats, and cavities that contribute significantly to gas transport, while retaining the void volume 41. The material system requires a relatively low pyrolysis temperature, which helps to reduce the impact of the processing on the dimensional state of the graphitized electrode core 1.

[0056] Example 4: This embodiment is used for a graphitized electrode core 1 with a high open porosity and a gas permeability higher than the preset process control value after a single limited impregnation.

[0057] First, a 25% (w / w) polycarbosilane xylene solution was used for the initial impregnation. A vacuum was drawn to a gauge pressure of -0.080 MPa and maintained for 20 minutes. The first impregnation material was then introduced under negative pressure and maintained for 20 minutes, after which atmospheric pressure was restored without applying any additional pressure. After draining and rotary purging, solvent removal, pre-curing, and pyrolysis under a nitrogen atmosphere at 1000°C were performed sequentially.

[0058] After the first heat treatment, the gas permeability of the test sample was measured. If the gas permeability was still higher than the preset value, a second limited impregnation was performed using a polycarbosilane xylene solution with a mass fraction of 15% to 20%. The vacuum gauge pressure for the second impregnation was controlled at -0.060 MPa to -0.075 MPa, and the holding time was 10 to 15 minutes, without positive pressure impregnation. After the second drainage, curing and pyrolysis were carried out under the same conditions as the first heat treatment.

[0059] The second impregnation uses a lower concentration, shorter time, and lower vacuum, so that the newly added oxygen-barrier reaction phase 31 mainly replenishes the pore throats and pore walls that still maintain high connectivity after the first treatment, reducing the possibility of continuously filling the surface interconnected pore network. After the second heat treatment, 0.20 mm to 0.30 mm of material is removed from the outer peripheral surface of the graphitized electrode core 1, and a molten sealing phase 51 is formed according to the second sealing slurry and shallow scraping method of Example 2.

[0060] In this embodiment, the annular witness sample and the block witness sample are processed simultaneously with the graphitized electrode core 1. The annular witness sample is used to detect axial resistivity and simulate clamping contact resistance, while the block witness sample is used for microscopic cross-sectional observation, energy dispersive spectroscopy (EDS) analysis, and industrial CT inspection. Cross-sectional inspection confirms that the oxygen-barrier reaction phase 31 is located inside the orifice, and the molten sealing phase 51 is located in the shallow part of the orifice. It also confirms that there are still cavities and throats between the two that are not completely filled by solid material.

[0061] As exemplary process control conditions, the statistical penetration depth of the oxygen-barrier reaction phase 31 can be controlled between 0.50 mm and 1.50 mm, the shallow embedding depth of the molten sealing phase 51 can be controlled between 0.05 mm and 0.40 mm, and the indentation of the outer surface of the molten sealing phase 51 relative to the outer peripheral reference surface of the graphite skeleton 11 can be controlled between 0.03 mm and 0.20 mm. These dimensions are adjusted according to the pore size distribution and electrode specifications of the graphitized electrode core 1, and it is not required that each pore has the same embedding depth and indentation.

[0062] After completing the anti-oxidation treatment, the threaded connection holes, axial mating end faces, and working end faces are subjected to final machining to ensure that the above-mentioned precision-fitted positions retain exposed graphite surfaces. Further testing is performed on the outer diameter, roundness, axial resistivity, clamping contact resistance, and gas permeability of the graphitized electrode core 1. When the increase in clamping contact resistance exceeds the preset control range, the amount of peripheral flexible brushing can be increased to further remove residual inorganic material between the orifices. When the witnessed sample shows that the molten sealing phase 51 penetrates too deeply and significantly compresses the void volume 41, the viscosity of the second sealing slurry can be increased, the elastic roller pressure reduced, or the slurry contact time shortened.

[0063] The antioxidant structures formed in the above embodiments all retain the exposed graphite surface between adjacent pores and protect the sealing material from the pore walls. This structure can restrict the transport of oxygen along the surface interconnected pore network into the graphitized electrode core 1, and utilize the oxygen-barrier reaction phase 31 to consume the small amount of oxygen that crosses the molten sealing phase 51. The locally generated reaction products can expand within the pore volume 41 and provide support for the softened molten sealing phase 51, thereby increasing the possibility of resealing the local pore cracks. This antioxidant structure mainly delays internal surface oxidation, pore expansion, and local erosion, and does not rely on completely eliminating the oxidation consumption of the exposed surface of the graphite skeleton 11.

[0064] Comparative Example 1: Graphitized electrode cores of the same specifications and batch as those used in the examples were selected, and their outer surfaces were subjected to dust collection, blowing, and drying. The graphitized electrode cores were placed in a sealed impregnation container, and a vacuum was drawn to remove the gas from the surface interconnected pores. A low-viscosity silicon-containing precursor impregnation solution was then introduced, followed by restoration to normal pressure or application of positive pressure to allow the impregnation solution to penetrate deep into the graphite micropores. After impregnation, curing and inert atmosphere heat treatment were performed directly. Impregnation was repeated one to two times depending on the gas permeability to ensure the impregnating material fully occupies the surface interconnected pores, forming a highly continuous permeation and sealing zone.

[0065] This comparative model can reduce the initial gas permeability of the graphitized electrode surface, but it does not intentionally retain the void volume between the oxygen barrier material and the pore sealing material within the pore network, nor does it set up a relatively independent shallow molten sealing phase. When cracks occur in the sealing area due to thermal cycling, the ability of the internal reaction products to directionally push and re-seal the pore cracks is relatively limited; at the same time, a high degree of filling may have a certain impact on the thermal stress release of the graphite skeleton and the gas buffering within the pores.

[0066] Comparative Example 2: Graphitized electrode cores of the same specifications and batch as those in the examples were selected, and their outer peripheral surfaces were cleaned and dried. An antioxidant slurry containing glass-forming components, silicon carbide powder, oxide powder, and inorganic binder was prepared. The slurry was continuously applied to the outer peripheral surface of the graphitized electrode core by spraying or roller coating. After drying, curing, and heat treatment, a continuous antioxidant coating layer was formed. The coating layer spans the openings of adjacent graphite micropores and covers the graphite surface between the openings.

[0067] This comparative example can simultaneously restrict oxygen contact with the outer surface of graphite and its entry into the surface pores. However, the continuous capping layer is directly exposed to clamping friction, furnace gas scouring, and repeated thermal cycling, which may lead to localized wear, cracking, or detachment. The continuous capping layer may also increase the contact resistance in the clamping area and form a residual shell during electrode descent and consumption. Therefore, its impact on clamping conductivity, working end consumption pattern, and furnace composition control is generally greater than that of a sealing structure locally embedded at the orifice.

[0068] Test Example 1: Thermal Cycling Antioxidant Performance Test To evaluate the antioxidant properties of different antioxidant structures under repeated heating and cooling conditions, cylindrical test specimens with a diameter of 50 mm and a length of 80 mm were processed from the same batch of graphite material. These specimens were treated according to the processes of Examples 1 to 4, Comparative Examples 1 and 2, respectively, with three parallel specimens in each group. The two end faces of the specimens were temporarily sealed with high-purity alumina refractory material, making the outer treated area the main oxidation exposure surface.

[0069] Each sample was placed in an air-atmosphere resistance furnace and heated to 800℃ at a rate of 5℃ / min. After holding at this temperature for 60 min, the samples were removed and allowed to cool naturally to room temperature, completing one thermal cycle. A total of five thermal cycles were performed. After each cooling, loose powder was removed from the surface, and the sample mass was weighed. The oxidation weight loss rate was calculated using the following formula: Oxidative weight loss rate = (mass before test - mass after test) / mass before test × 100%.

[0070] Another graphite sample from the same batch that was not treated with antioxidant was taken as the test benchmark. The test results were taken as the arithmetic mean of three parallel samples, as shown in Table 1.

[0071] Table 1 Results of thermal cycling antioxidant performance test

[0072] As shown in Table 1, both the permeation sealing structure in Comparative Example 1 and the continuous surface coating in Comparative Example 2 exhibited low initial weight loss rates during the first thermal cycle, with the continuous surface coating demonstrating a strong barrier effect against initial oxygen ingress. However, with increasing thermal cycles, the sealing area in Comparative Example 1 was prone to cracking due to internal constraints and differences in thermal expansion, while the continuous coating in Comparative Example 2 showed localized cracking and edge detachment, leading to an increase in its cumulative oxidation weight loss rate.

[0073] The cumulative weight loss rates of Examples 1 to 4 after five thermal cycles were 4.39% to 5.08%, which were generally lower than those of the two comparative examples. This is because the molten sealing phase in the shallow part of the pores restricts the initial entry of oxygen, the pore volume provides space for the expansion of local reaction products and the release of thermal stress, and the oxygen-barrier reaction phase consumes some of the oxygen beyond the sealing position. These results indicate that the structure of this application is beneficial for improving the sustained effectiveness of the antioxidant structure under repeated thermal cycling conditions, but it still cannot completely eliminate oxidation consumption in the exposed graphite areas.

[0074] Test Example 2: Clamping Contact Resistance Test To evaluate the effect of antioxidant treatment on the conductivity of the electrode clamping, cylindrical specimens with similar outer diameters and surface roughness were selected from the witness specimens corresponding to each embodiment and comparative example, with three parallel specimens set up for each group. Two copper clamping plates were used to clamp the outer circumference of the specimens, maintaining a clamping pressure of 0.60 MPa. A 100 A DC current was applied to the specimens, and the voltage drop between the clamping plates and the specimens was measured using the four-terminal method. The contact resistance was calculated based on the voltage drop and current.

[0075] The contact resistance was measured before and after the antioxidant treatment, as well as after twenty repeated clamping and releasing cycles. The same pressure and clamping position range were maintained for each clamping cycle. The test results were taken as the arithmetic mean of three parallel samples, as shown in Table 2.

[0076] Table 2. Clamping Contact Resistance Test Results

[0077] As shown in Table 2, the clamping contact resistance of Examples 1 to 4 increased by 3.5% to 5.7% after anti-oxidation treatment. Since the molten sealing phase is mainly embedded in the shallow part of the graphite micropore openings, and the exposed graphite surface is still retained between adjacent openings, the copper clamping plate can directly form a large area of ​​contact with the graphite skeleton, so the impact on the clamping conductivity is relatively limited.

[0078] Comparative Example 1 employed a more thorough penetration sealing treatment, resulting in a higher proportion of non-graphite areas at the orifice and adjacent surfaces, leading to a slight increase in contact resistance. Comparative Example 2, with its continuous anti-oxidation coating covering the graphite surface between the orifices, exhibited a significant increase in contact resistance after treatment. After repeated clamping, the contact resistance of Comparative Example 2 decreased somewhat, mainly due to wear and localized peeling of the continuous coating; however, its surface contact was uneven, and the contact resistance remained significantly higher than in the other examples, accompanied by coating damage.

[0079] Test Example 3: Simulation Test of Impurity Introduction into the Furnace To evaluate the potential impact of different antioxidant treatment materials on the composition of molten steel after entering the furnace, a laboratory medium-frequency induction furnace was used for simulation testing. Each test involved melting 20 kg of the same batch of low-carbon steel, using the same composition and amount of covering slag. After the molten steel temperature stabilized at 1600℃±20℃, samples were first taken to test the initial composition. Then, samples with the same treatment area were placed near the slag-steel interface and kept for 20 minutes, subjecting the samples to high temperature, furnace gas scouring, and slag splashing.

[0080] After the test, the samples were removed, the molten steel was stirred evenly, and samples were taken again. The contents of silicon, aluminum, boron, phosphorus, sodium, and potassium were determined by inductively coupled plasma atomic emission spectrometry. The values ​​listed in Table 3 are the increases in content after the test relative to the initial molten steel content. Three independent heats were tested for each group, and the arithmetic mean was taken.

[0081] Table 3. Increase in impurity elements in molten steel

[0082] As shown in Table 3, Examples 1 to 4 had a certain impact on the content of silicon, aluminum, and alkali metals in molten steel, but the overall increase in each element remained at a low level. Among them, Example 2 used a low-phosphorus and low-boron sealing material system, and its increase in boron and phosphorus was relatively low.

[0083] In Comparative Example 1, the sealing material is mainly located inside the graphite mesh, with a relatively small amount directly entering the molten steel. Therefore, its increase in impurities is similar to that of the embodiments, with some indicators being slightly lower. This result indicates that the main advantages of this application over the permeation sealing technology lie in its thermal cycling oxidation resistance and clamping conductivity, and it is not necessary to claim superiority over the permeation sealing structure in all impurity indicators.

[0084] Comparative Example 2 uses a continuous surface anti-oxidation coating, resulting in a larger amount of inorganic material carried per unit electrode surface. Furthermore, under high-temperature erosion and thermal stress, the coating easily forms fragments or powder that enter the slag-steel region, leading to a higher increase in silicon, aluminum, and alkali metals compared to the other groups. Examples 1 to 4 retain only a small amount of molten sealing phase in the shallow part of the orifice, with the graphite surface between adjacent orifices remaining exposed. This reduces the possibility of forming a large-area continuous residual shell, thus facilitating the control of the impact of the anti-oxidation material on the furnace composition.

[0085] As can be seen from Tables 1 to 3, Examples 1 to 4 exhibit lower cumulative oxidation weight loss rates under repeated thermal cycling conditions, and the increase in clamping contact resistance after treatment is relatively small. The amount of impurities introduced into the furnace is close to that of the permeation sealing structure, and significantly lower than that of the continuous surface coating structure.

[0086] The above test results indicate that the combination of the oxygen-barrier reaction phase, the pore volume, and the shallow molten sealing phase at the orifice is beneficial for achieving a relatively reasonable balance between antioxidant durability, clamping conductivity, and the amount of material introduced into the furnace. Specifically, Example 4 performed relatively well in the thermal cycling antioxidant test, while Example 2 showed relatively stable performance in terms of clamping contact resistance and impurity control. However, the differences between the examples did not reach a level that could exclude the influence of material batch and porosity randomness; therefore, it is inappropriate to describe any one of the examples as the absolutely optimal solution.

[0087] The technical scope of this invention is not limited to the content described above. Those skilled in the art can make various modifications and variations to the above embodiments without departing from the technical concept of this invention, and all such modifications and variations should fall within the protection scope of this invention.

Claims

1. An antioxidant graphitized electrode for an electric furnace, characterized in that, The device includes a graphitized electrode core comprising a graphite skeleton with a plurality of graphite micropores, at least some of which are interconnected to form a surface interconnected pore network, and orifices are formed on the outer peripheral surface of the graphite skeleton; an oxygen-barrier reactive phase is disposed within the surface interconnected pore network, the oxygen-barrier reactive phase is distributed on the inner side of the corresponding orifice and together forms an oxygen-barrier reactive layer, a molten sealing phase is embedded in the shallow part of the orifice, and multiple molten sealing phases together form a molten sealing layer, and a void volume not completely filled by solid material is retained between the oxygen-barrier reactive phase and the corresponding molten sealing phase, and multiple void volumes together form a void buffer layer; the outer surface of the molten sealing phase is lower than the outer peripheral reference surface of the graphite skeleton to form a surface reserved opening at the corresponding orifice, and multiple surface reserved openings together form a remaining opening layer, and the graphite surface between adjacent orifices remains exposed. The molten sealing phase is composed of a sealing material that can soften or melt when heated during electrode use. The oxygen barrier reaction phase is composed of an oxygen barrier material that can react with oxygen to form reaction products that increase in volume. When oxygen enters the corresponding void volume through the cracks or gaps of the molten sealing phase, the oxygen barrier reaction phase consumes the entering oxygen and causes the formed reaction products to expand toward the corresponding molten sealing phase, so that the molten sealing phase in the molten state is redistributed toward the corresponding orifice.

2. The method for using an antioxidant graphitized electrode for an electric furnace according to claim 1, characterized in that: S1. The graphitized electrode core with a graphite skeleton and a surface interconnected mesh is cleaned and dried so that the openings of the surface interconnected mesh remain open. S2. Under negative pressure, the first impregnating material is introduced into the surface interconnecting mesh, and then the free first impregnating material is discharged. The first impregnating material attached to the pore wall, pore throat and local pore cavity is cured and heat-treated to form an oxygen barrier reaction phase that can react with oxygen, and to retain pores in the surface interconnecting mesh that are not completely occupied by the oxygen barrier reaction phase. S3. Remove the continuous residue on the outer peripheral surface of the graphitized electrode core and some oxygen-barrier reaction phase in the shallow part of the orifice, so that the orifice is reopened and a filling space is formed in the shallow part of the orifice. S4. Press a second sealing slurry with a viscosity higher than that of the first impregnating material into the filling space, so that the second sealing slurry forms a molten sealing phase in the shallow part of the orifice that can be softened or melted by heat, and retains a void volume between the molten sealing phase and the corresponding oxygen barrier reaction phase; S5. Remove the second sealing slurry between adjacent orifices and above the outer peripheral reference surface of the graphite skeleton, so that the outer surface of the molten sealing phase is lower than the outer peripheral reference surface, and the graphite surface between adjacent orifices remains exposed.

3. The method for using an antioxidant graphitized electrode for an electric furnace according to claim 2, characterized in that: In step S1, the graphitized electrode core is rough machined on its outer diameter, and the formed threaded connection hole and axial joint end face are covered with solvent-resistant shielding. After rough machining of the outer diameter, the graphite powder and moisture near the hole are removed by vacuum dust collection, dry gas blowing and heating drying in sequence.

4. The method for using an antioxidant graphitized electrode for an electric furnace according to claim 2, characterized in that: Before introducing the first impregnation material, the open porosity, pore size distribution and gas permeability of the witness samples from the same batch as the graphitized electrode core are tested, and the effective pore range that makes the main contribution to gas transport in the surface interconnected pore network is determined based on the test results.

5. The method for using an antioxidant graphitized electrode for an electric furnace according to claim 2, characterized in that: In step S2, the graphitized electrode core is placed in a sealed impregnation container. First, a vacuum is drawn to remove the gas in the surface interconnecting mesh. Then, the first impregnation material is introduced under negative pressure. Subsequently, normal pressure is restored or a controlled pressure is applied to allow the first impregnation material to enter the surface interconnecting mesh.

6. The method for using an antioxidant graphitized electrode for an electric furnace according to claim 2, characterized in that: The first impregnation material includes an organosilicon precursor liquid, or a dispersion formed by a high residual carbon resin and silicon carbide particles; after curing and heat treatment, the first impregnation material forms a silicon carbide reactive phase, a silicon-oxygen-carbon ceramic phase, or a silicon carbide reactive phase with residual carbon.

7. The method for using an antioxidant graphitized electrode for an electric furnace according to claim 2, characterized in that: Before the formation of the oxygen-barrier reaction phase, the graphitized electrode core is rotated along the axis, and the free first impregnation material on the outer surface and in the pores is removed by inert gas purging or vacuum extraction. Subsequently, solvent removal, pre-curing and inert atmosphere pyrolysis or ceramic treatment are performed in sequence, so that the oxygen-barrier reaction phase is distributed in the surface interconnected pore network in the form of pore wall deposits, local fillers or particle aggregates.

8. The method for using an antioxidant graphitized electrode for an electric furnace according to claim 2, characterized in that: In step S3, the continuous residue is removed by external circular finishing, flexible brushing or sandblasting and the orifice is exposed again. The removal depth of the continuous residue is less than the penetration depth of the first impregnating material in the graphitized electrode core, so that the oxygen barrier reaction phase is retained inside the orifice.

9. The method for using an antioxidant graphitized electrode for an electric furnace according to claim 2, characterized in that: The second sealing slurry is thixotropic and includes a glass-forming component, silicon carbide powder, carbonaceous powder, and an inorganic binder; the glass-forming component forms a highly viscous softening phase at the electrode operating temperature.

10. The method for using an antioxidant graphitized electrode for an electric furnace according to claim 2, characterized in that: In step S4, the second sealing slurry is pressed into the shallow part of the orifice by elastic roller coating, scraping coating or flexible pressure coating; after the second sealing slurry is initially shaped, the outer peripheral surface of the graphitized electrode core is scraped back, flexibly brushed or polished, and solvent discharge, binder curing and stabilization treatment are performed in sequence to form a surface reserved opening located outside the molten sealing phase.

Images