Novel method for insulating directional wheel of submerged arc furnace coil base

Abstract

The invention relates to the technical field of composite material forming processes, and particularly discloses a novel method for insulating a directional wheel of a submerged arc furnace coil base. The novel submerged arc furnace coil base directional wheel insulation method comprises the following steps: S1, raw material preparation: preparing the following raw materials: a modified epoxy resin matrix, a curing agent, a flaky inorganic filler, a flexibilizer and a coupling agent; s2, filler pretreatment; s3, mixing and dispersing; s4, adding a curing agent and defoaming: adding the curing agent in the step S1 into the resin mixture obtained in the step S3, stirring, and then standing and defoaming to obtain the pourable insulating slurry; s5, mold preheating and pouring; s6, step curing is conducted; and S7, carrying out post-treatment and processing. The novel insulating method for the submerged arc furnace coil base directional wheel can be used for high-performance insulating coating manufacturing of the submerged arc furnace coil base directional wheel and has the advantages of being compact and complete in insulating layer, firm in interface bonding and excellent in comprehensive performance.

Description

Technical Field

[0001] This application relates to the field of composite material molding technology, and more specifically, it relates to a novel method for insulating the directional wheel of a submerged arc furnace platform. Background Technology

[0002] As a key load-bearing and guiding component for the movement and positioning of the submerged arc furnace platform, the directional rollers are mostly made of resin-based composite materials and processed through methods such as compression molding, filament winding, and pultrusion. Compression molding can precisely control the dimensional accuracy and structural density of the roller body, meeting the stringent requirements for form and position tolerances. Filament winding optimizes the orientation of the stressed fibers in the roller body, improving impact resistance and fatigue resistance. Pultrusion is suitable for mass production of the roller body frame or rim substrate, balancing strength and production efficiency. During the molding process, formula optimization and post-processing techniques give the composite material directional rollers advantages such as light weight, wear and corrosion resistance, high temperature resistance, and vibration and noise reduction. This effectively solves the problems of easy wear, corrosion, and high operating noise of traditional metal directional rollers, making them suitable for the harsh working environment of submerged arc furnaces with high temperature, dust, and heavy loads, ensuring smooth and precise movement of the furnace platform and extending the service life of the components.

[0003] The directional wheels of the related submerged arc furnace platform are formed by conventional thermosetting process. However, the process often results in problems such as microcracks, interface debonding, and uneven distribution of fillers in the composite material due to inaccurate control of the curing reaction rate or insufficient bonding force between the filler and the resin interface. This reduces the arc resistance and mechanical stability of the component. Summary of the Invention

[0004] To address the issue of reduced arc resistance and mechanical stability of directional wheels for submerged arc furnace platforms due to conventional thermosetting processes, this application provides a novel method for insulating directional wheels for submerged arc furnace platforms.

[0005] This application provides a novel method for insulating the directional wheel of a submerged arc furnace platform, employing the following technical solution: A new method for insulating the directional wheel of a submerged arc furnace platform includes the following steps: S1. Raw material preparation: Prepare the following raw materials in parts by weight: 100 parts modified epoxy resin matrix, 20-35 parts curing agent, 50-80 parts flake inorganic filler, 5-15 parts toughening agent and 1-3 parts coupling agent. S2. Pretreatment of filler: The sheet-like inorganic filler is placed in a high-temperature furnace and calcined at 450~550℃ for 60~120 minutes to obtain activated filler. After cooling, the activated filler is placed in an ethanol solution containing a portion of coupling agent. S3. Mixing and dispersing: The modified epoxy resin matrix from step S1, the activated filler, toughening agent and remaining coupling agent obtained from step S2 are put into a mixing tank and stirred at 300-500 rpm for 40-90 minutes under the conditions of 60-80℃ and vacuum degree of -0.08 to -0.095MPa to obtain a uniform resin mixture. S4. Adding curing agent and degassing: Add the curing agent from step S1 to the resin mixture obtained in step S3, stir at 150-250 rpm for 15-30 minutes at 40-50℃, and then let it stand under vacuum of -0.09--0.1MPa for 20-40 minutes to degas, and obtain a castable insulating slurry. S5. Mold preheating and casting: The surface of the directional wheel metal core is sandblasted to remove rust and preheated to 70~90℃. The preheated metal core is placed into a mold preheated to 80~100℃. Then, the pourable insulating slurry obtained in step S4 is poured into the mold cavity to completely cover the metal core. S6. Step Curing: Place the mold that has been poured in step S5 into a curing oven and perform the following steps in sequence: First stage curing: hold at 85~95℃ for 2~4 hours; Second stage curing: raise the temperature to 120~130℃ at a rate of 0.5~1℃ / min and hold for 3~5 hours; Third stage curing: raise the temperature to 150~160℃ at a rate of 1~2℃ / min and hold for 2~3 hours. S7. Post-processing and machining: After curing in step S6, the mold is cooled and demolded to obtain the insulating directional wheel blank. It is then machined to the specified dimensions to obtain the final insulating directional wheel product.

[0006] By adopting the above technical solution, the modified epoxy resin system can achieve orderly cross-linking of molecular chains through a stepped heating and curing process and by controlling the temperature and time parameters at each stage, thus avoiding the problem of internal stress accumulation caused by excessively rapid curing reaction. At the same time, by performing high-temperature activation and coupling agent surface modification treatment on the sheet-like inorganic filler, the interfacial bonding strength between the filler and the resin matrix is ​​enhanced, allowing the sheet-like filler to be oriented during the curing process and form an anti-permeation barrier. Therefore, the final insulating oriented wheel product exhibits a dense microstructure, possesses high arc resistance, high mechanical strength, and long-term thermal stability, and can withstand the high temperature, strong vibration, and metal dust corrosion in the environment of a submerged arc furnace.

[0007] Preferably, in step S1, the sheet-like inorganic filler is muscovite powder or sericite powder that has undergone flake treatment, with a particle size D50 controlled at 15~45μm and an aspect ratio greater than 50.

[0008] By adopting the above technical solution, since flake-shaped muscovite powder or sericite powder with an aspect ratio greater than 50 is selected as the main inorganic filler, the filler with this specific shape and size is easy to achieve directional arrangement in the plane of the insulation layer during subsequent stirring, casting and curing processes, thereby extending the diffusion path of corrosive media; at the same time, controlling the particle size D50 to 15~45μm can ensure that the filler can maintain sufficient dispersion and fluidity in the resin system to avoid agglomeration, while also providing a reinforcing effect; therefore, this preferred solution synergistically improves the barrier performance and mechanical properties of the insulation layer, giving it a longer service life under the high temperature and high humidity conditions of the submerged arc furnace.

[0009] Preferably, the modified epoxy resin matrix in step S1 is a phenolic modified epoxy resin or an organosilicon modified epoxy resin.

[0010] By adopting the above technical solutions, the phenolic modified epoxy resin introduces a phenolic skeleton structure, which improves the crosslinking density and heat resistance of the cured epoxy resin product, thereby increasing its glass transition temperature. Meanwhile, the organosilicon modified epoxy resin introduces silicon-oxygen bonds, giving the cured product flexibility and hydrophobicity, reducing the risk of cracking caused by thermal cycling. The selection of these two modified epoxy resin matrices is based on the specific working conditions of the directional wheel of the submerged arc furnace, which needs to withstand high heat load and mechanical stress at the same time. Its molecular structure characteristics affect the high-temperature dimensional stability and thermal shock resistance of the final insulation layer.

[0011] Preferably, the toughening agent is carboxylated nitrile rubber; the curing agent is methyltetrahydrophthalic anhydride or methylnadic anhydride.

[0012] By adopting the above technical solution, the carboxyl functional groups in the carboxyl-based nitrile rubber can react with the epoxy groups to form chemical bonds, thereby generating an elastic phase in situ within the rigid epoxy network to absorb and disperse stress. Methyltetrahydrophthalic anhydride or methylnadic anhydride is chosen as the curing agent because these two anhydride curing agents have moderate reactivity with the selected epoxy resin to perform step-curing as described in step S6, and their cured products have high heat distortion temperature and good electrical insulation properties. Therefore, this preferred solution, through material compatibility, improves the toughness of the insulation layer while ensuring its heat resistance level, thus avoiding brittle fracture.

[0013] Preferably, in step S2, after calcination, the activated filler is naturally cooled to below 80°C, and then immersed in an ethanol solution containing 50% to 70% of the total coupling agent for wet surface modification. The modification time is 20 to 40 minutes, and then it is dried to obtain the surface-modified activated filler for use in step S3.

[0014] By adopting the above technical solution, the filler after high-temperature calcination is cooled to below 80°C, which avoids microcracks caused by rapid cooling and maintains its surface activation state. Subsequently, a partial coupling agent is used for pre-wet surface treatment, which allows the coupling agent molecules to coat the filler surface. In the subsequent S3 step, when mixed with the resin matrix, these pre-grafted coupling agents can more effectively promote the chemical bonding between the resin and the filler, improve interfacial compatibility, and reduce performance degradation caused by interfacial defects. This pretreatment process ensures that a uniform and defect-free insulating slurry is finally obtained.

[0015] Preferably, in step S3, the viscosity of the resin mixture is controlled to be 8000~15000 mPa·s.

[0016] By adopting the above technical solution, the viscosity of the resin mixture in this step is precisely controlled between 8000 and 15000 mPa·s. This improved viscosity range ensures that the sheet filler remains in good suspension in the system without settling, while also having sufficient fluidity during the subsequent S5 casting process to smoothly fill the mold cavity and completely cover the metal core. This viscosity control is a process node connecting the preceding mixing and dispersion process with the subsequent casting and molding process, affecting the density and uniformity of the insulation layer.

[0017] Preferably, in step S4, while adding the curing agent, a defoamer accounting for 0.5% to 2% of the total mass of the resin mixture is also added, and the defoamer is an organosilicon defoamer.

[0018] By adopting the above technical solution, an organosilicon defoamer is introduced simultaneously when the curing agent is added and low-speed stirring begins. This defoamer can reduce the surface tension of the slurry system, causing the bubble film walls that have risen to the surface of the slurry during the vacuum degassing process to rupture. This measure specifically solves the problem of bubbles introduced by the addition of fillers and stirring, and works synergistically with the subsequent vacuum settling degassing process to ensure that there are no visible bubbles inside the castable insulating slurry, thereby eliminating the hidden danger of partial discharge breakdown of the insulation layer caused by the presence of bubbles.

[0019] Preferably, in step S5, after sandblasting and rust removal of the surface of the directional wheel metal core, it is further cleaned and dried using an organic solvent, wherein the organic solvent is acetone or ethanol.

[0020] By adopting the above technical solution, after sandblasting to remove oxide scale and rust from the metal core surface, further cleaning with organic solvents such as acetone or ethanol can remove residual dust and any oil contaminants from sandblasting, resulting in a highly active and clean metal surface.

[0021] Preferably, in the first stage of curing in step S6, a pressure of 0.2~0.5MPa is applied to the mold.

[0022] By adopting the above technical solution, the external pressure of 0.2~0.5MPa applied to the mold during the initial low-temperature stage of stepped curing compensates for the slight volume shrinkage of the resin system caused by thermal expansion and solvent evaporation before gelation. At the same time, it forces the slurry to adhere tightly to the surface of the metal core and expel residual trace gases. This pressurization operation, combined with long-term low-temperature heat preservation, helps to form a dense initial cross-linked network, providing a stable basis for the full movement and orderly arrangement of molecular chains during subsequent high-temperature curing, and suppressing internal porosity and delamination of the cured product.

[0023] Preferably, in step S7, the cooling rate is controlled to be no more than 1°C / min, and the temperature is slowly cooled to below 80°C, and then cooled to below 60°C with the furnace.

[0024] By adopting the above technical solution, the cooling rate of the cured product is controlled within 1℃ / min for slow cooling. This slow cooling process allows the cured epoxy resin crosslinking network sufficient time to relax stress, avoiding thermal stress concentration caused by excessive internal and external temperature differences. When slowly passing through the glass transition temperature region, the residual internal stress of the product can be reduced, thereby preventing the insulating directional wheel from warping or developing microcracks during the cooling process, ensuring the stability of the final product's dimensional accuracy and insulation reliability.

[0025] In summary, this application has the following beneficial effects: 1. Because this application adopts a stepped heating curing process and controls the temperature and time parameters of each stage, and combines high-temperature activation of the sheet-like inorganic filler and surface modification treatment of the coupling agent, the stepped curing promotes the orderly cross-linking of epoxy resin molecular chains, avoiding the problem of internal stress accumulation caused by excessively fast curing reaction. The filler pretreatment enhances the interfacial bonding strength between the filler and the resin matrix, and guides the filler to be oriented and arranged in an anti-permeability barrier during the curing process. As a result, the insulating directional wheel obtains high arc resistance, high mechanical strength and long-term thermal stability, and can reliably withstand the high temperature, strong vibration and metal dust corrosion in the environment of the electric arc furnace.

[0026] 2. In this application, flake-shaped mica powder or sericite powder with a diameter-to-thickness ratio greater than 50 is preferably used as the main inorganic filler. The filler with this specific shape and size is easy to achieve directional arrangement along the plane of the insulation layer during the stirring, casting and curing stages, which prolongs the diffusion path of corrosive media. At the same time, the particle size is controlled within a certain range to ensure that the filler maintains dispersion and fluidity in the resin system to avoid agglomeration and provides a reinforcing effect. Therefore, the barrier performance and mechanical properties are synergistically improved, so that the insulation layer has a long service life under the high temperature and high humidity conditions of the electric arc furnace.

[0027] 3. The method of this application, by applying appropriate external pressure to the mold in the initial stage of stepped curing and combining it with long-term low-temperature heat preservation, can effectively compensate for the volume shrinkage of the system caused by thermal expansion and solvent evaporation before the resin gels. This forces the slurry to adhere tightly to the surface of the metal core and expel residual trace gases, thereby providing a dense structural basis for the orderly arrangement of molecular chains in the subsequent high-temperature curing stage. Therefore, it inhibits the formation of internal pores and delamination in the cured product and ensures the overall structural density of the insulation layer and its dimensional stability under long-term service. Attached Figure Description

[0028] Figure 1 This is a flowchart of a new method for insulating the directional wheel of a submerged arc furnace platform proposed in this application. Detailed Implementation

[0029] The present application will be further described in detail below with reference to the accompanying drawings and embodiments.

[0030] Technical concept: The directional wheels of the related submerged arc furnace platform are formed by conventional thermosetting process. However, the process often results in problems such as microcracks, interface debonding, and uneven distribution of fillers in the composite material due to inaccurate control of the curing reaction rate or insufficient bonding force between the filler and the resin interface. This reduces the arc resistance and mechanical stability of the component.

[0031] This application discloses a novel method for insulating the directional wheel of a submerged arc furnace platform, comprising the following steps: S1, raw material preparation: preparing the following raw materials: modified epoxy resin matrix, curing agent, flake inorganic filler, toughening agent, and coupling agent; S2, filler pretreatment; S3, mixing and dispersion; S4, curing agent addition and degassing: adding the curing agent from step S1 to the resin mixture obtained in step S3 and stirring, then allowing it to stand to degas, obtaining a castable insulating slurry; S5, mold preheating and casting; S6, step curing; S7, post-treatment and processing.

[0032] This application employs a stepped heating curing process and controls the temperature and time parameters at each stage. It also combines high-temperature activation of the sheet-like inorganic filler with surface modification treatment of the coupling agent. The stepped curing promotes the orderly cross-linking of epoxy resin molecular chains, avoiding the problem of internal stress accumulation caused by excessively rapid curing reaction. The filler pretreatment enhances the interfacial bonding strength between the filler and the resin matrix and guides the filler to oriented arrangement during the curing process to form an anti-permeation barrier. This results in the insulating directional wheel having high arc resistance, high mechanical strength, and long-term thermal stability, enabling it to reliably withstand the high temperature, strong vibration, and metal dust corrosion in the environment of the submerged arc furnace.

[0033] Example 1 This embodiment provides a novel method for insulating the directional wheel of a submerged arc furnace platform, comprising the following steps: S1. Raw material preparation: Prepare the following raw materials in parts by weight: 100 parts modified epoxy resin matrix, 20 parts curing agent, 50 parts flake inorganic filler, 5 parts toughening agent and 1 part coupling agent. The sheet-like inorganic filler is scaly mica powder that has undergone flake treatment, with a particle size D50 controlled at 15μm and an aspect ratio greater than 50; the modified epoxy resin matrix is ​​phenolic modified epoxy resin; the toughening agent is carboxylated nitrile rubber; and the curing agent is methyltetrahydrophthalic anhydride.

[0034] S2. Pretreatment of filler: Place the sheet-like inorganic filler in a high-temperature furnace and calcine it at 450°C for 60 minutes to obtain activated filler. After cooling, the activated filler is placed in an ethanol solution containing a portion of coupling agent. After calcination, the activated filler is naturally cooled to below 80°C, and then immersed in an ethanol solution containing 50% of the total coupling agent for wet surface modification. The modification time is 20 minutes, and then it is dried to obtain the surface-modified activated filler, which is used in step S3.

[0035] S3. Mixing and dispersing: The modified epoxy resin matrix from step S1, the activated filler, toughening agent and remaining coupling agent obtained from step S2 are put into a mixing tank and stirred at 300 rpm for 40 minutes under the conditions of 60℃ and vacuum degree -0.08MPa to obtain a uniform resin mixture. The viscosity of the resin mixture is controlled to be 8000 mPa·s.

[0036] S4. Adding curing agent and degassing: Add the curing agent from step S1 to the resin mixture obtained in step S3, stir at 150 rpm for 15 minutes at 40°C, and then let it stand under vacuum of -0.09 MPa for 20 minutes to degas, so as to obtain a castable insulating slurry. In addition to the curing agent, a defoamer accounting for 0.5% of the total mass of the resin mixture is also added. The defoamer is an organosilicon defoamer.

[0037] S5. Mold preheating and casting: The surface of the directional wheel metal core is sandblasted to remove rust and preheated to 70°C. The preheated metal core is placed into a mold preheated to 80°C. Then, the pourable insulating slurry obtained in step S4 is poured into the mold cavity to completely cover the metal core. After sandblasting to remove rust from the surface of the directional wheel's metal core, it is also cleaned and dried using an organic solvent, namely acetone.

[0038] S6, Step Curing: Place the mold that has been poured in step S5 into a curing oven and perform the following steps in sequence: First stage curing: hold at 85℃ for 2 hours; Second stage curing: heat up to 120℃ at a rate of 0.5℃ / min and hold for 3 hours; Third stage curing: heat up to 150℃ at a rate of 1℃ / min and hold for 2 hours. In the first stage of curing, a pressure of 0.2 MPa is applied to the mold.

[0039] S7. Post-processing and machining: After curing in step S6, the mold is cooled and demolded to obtain the insulating directional wheel blank. It is then machined to the specified size to obtain the final insulating directional wheel product. The cooling rate is controlled to be no more than 1℃ / min, with a specific cooling rate of 0.3℃ / min. The temperature is slowly cooled to below 80℃, and then cooled to below 60℃ along with the furnace.

[0040] Example 2 This embodiment provides a novel method for insulating the directional wheel of a submerged arc furnace platform, comprising the following steps: S1. Raw material preparation: Prepare the following raw materials in parts by weight: 100 parts modified epoxy resin matrix, 28 parts curing agent, 65 parts flake inorganic filler, 10 parts toughening agent and 2 parts coupling agent. The sheet-like inorganic filler is sericite powder that has undergone flake treatment, with a particle size D50 controlled at 30μm and an aspect ratio greater than 50, specifically 60; the modified epoxy resin matrix is ​​silicone-modified epoxy resin; the toughening agent is carboxylated nitrile rubber; and the curing agent is methyl nadic anhydride.

[0041] S2. Pretreatment of filler: Place the sheet-like inorganic filler in a high-temperature furnace and calcine it at 500°C for 90 minutes to obtain activated filler. After cooling, the activated filler is placed in an ethanol solution containing a portion of coupling agent. After calcination, the activated filler is naturally cooled to below 80°C, and then immersed in an ethanol solution containing 60% of the total coupling agent for wet surface modification. The modification time is 30 minutes, and then it is dried to obtain the surface-modified activated filler, which is used in step S3.

[0042] S3. Mixing and dispersing: The modified epoxy resin matrix from step S1, the activated filler, toughening agent and remaining coupling agent obtained from step S2 are put into a mixing tank and stirred at 400 rpm for 65 minutes under the conditions of 70℃ and vacuum degree -0.09MPa to obtain a uniform resin mixture. The viscosity of the resin mixture was controlled to be 11500 mPa·s.

[0043] S4. Adding curing agent and degassing: Add the curing agent from step S1 to the resin mixture obtained in step S3, stir at 200 rpm for 22 minutes at 45°C, and then let it stand under vacuum of -0.095 MPa for 30 minutes to degas, and obtain a castable insulating slurry. In addition to the curing agent, a defoamer accounting for 1.2% of the total mass of the resin mixture is also added. The defoamer is an organosilicon defoamer.

[0044] S5. Mold preheating and casting: The surface of the metal core of the directional wheel is sandblasted to remove rust and preheated to 80°C. The preheated metal core is placed into a mold preheated to 90°C. Then, the pourable insulating slurry obtained in step S4 is poured into the mold cavity to completely cover the metal core. In this process, after sandblasting to remove rust from the surface of the metal core of the directional wheel, an organic solvent, namely ethanol, is used for cleaning and drying.

[0045] S6, Step Curing: Place the mold that has been poured in step S5 into a curing oven and perform the following steps in sequence: First stage curing: hold at 90℃ for 3 hours; Second stage curing: heat up to 125℃ at a rate of 0.75℃ / min and hold for 4 hours; Third stage curing: heat up to 155℃ at a rate of 1.5℃ / min and hold for 2.5 hours. In the first stage of curing, a pressure of 0.35 MPa is applied to the mold.

[0046] S7. Post-processing and machining: After curing in step S6, the mold is cooled and demolded to obtain the insulating directional wheel blank. It is then machined to the specified size to obtain the final insulating directional wheel product. The cooling rate is controlled to be no more than 1℃ / min, with a specific cooling rate of 0.5℃ / min. The temperature is slowly cooled to below 80℃, and then cooled to below 60℃ along with the furnace.

[0047] Example 3 This embodiment provides a novel method for insulating the directional wheel of a submerged arc furnace platform, comprising the following steps: S1. Raw material preparation: Prepare the following raw materials in parts by weight: 100 parts modified epoxy resin matrix, 35 parts curing agent, 80 parts flake inorganic filler, 15 parts toughening agent and 3 parts coupling agent. The sheet-like inorganic filler is scaly mica powder that has undergone flake treatment, with a particle size D50 controlled at 45μm and an aspect ratio greater than 50, specifically 65; the modified epoxy resin matrix is ​​phenolic modified epoxy resin; the toughening agent is carboxylated nitrile rubber; and the curing agent is methyltetrahydrophthalic anhydride.

[0048] S2. Pretreatment of filler: Place the sheet-like inorganic filler in a high-temperature furnace and calcine it at 550°C for 120 minutes to obtain activated filler. After cooling, the activated filler is placed in an ethanol solution containing a portion of coupling agent. After calcination, the activated filler is naturally cooled to below 80°C and then immersed in an ethanol solution containing 70% of the total coupling agent for wet surface modification. The modification time is 40 minutes, and then it is dried to obtain the surface-modified activated filler, which is used in step S3.

[0049] S3. Mixing and dispersing: The modified epoxy resin matrix from step S1, the activated filler, toughening agent and remaining coupling agent obtained from step S2 are put into a mixing tank and stirred at 500 rpm for 90 minutes under the conditions of 80℃ and vacuum degree -0.095MPa to obtain a uniform resin mixture. The viscosity of the resin mixture is controlled to be 15000 mPa·s.

[0050] S4. Adding curing agent and degassing: Add the curing agent from step S1 to the resin mixture obtained in step S3, stir at 250 rpm for 30 minutes at 50°C, and then let it stand under vacuum of -0.1 MPa for 40 minutes to degas, so as to obtain a castable insulating slurry. In addition to the curing agent, a defoamer accounting for 2% of the total mass of the resin mixture is also added. The defoamer is an organosilicon defoamer.

[0051] S5. Mold preheating and casting: The surface of the directional wheel metal core is sandblasted to remove rust and preheated to 90°C. The preheated metal core is placed into a mold preheated to 100°C. Then, the pourable insulating slurry obtained in step S4 is poured into the mold cavity to completely cover the metal core. After sandblasting to remove rust from the surface of the directional wheel's metal core, it is also cleaned and dried using an organic solvent, namely acetone.

[0052] S6, Step Curing: Place the mold that has been poured in step S5 into a curing oven and perform the following steps in sequence: First stage curing: hold at 95℃ for 4 hours; Second stage curing: heat up to 130℃ at a rate of 1℃ / min and hold for 5 hours; Third stage curing: heat up to 160℃ at a rate of 2℃ / min and hold for 3 hours. In the first stage of curing, a pressure of 0.5 MPa is applied to the mold.

[0053] S7. Post-processing and machining: After curing in step S6, the mold is cooled and demolded to obtain the insulating directional wheel blank. It is then machined to the specified size to obtain the final insulating directional wheel product. The cooling rate is controlled to be no more than 1℃ / min, with a specific cooling rate of 0.8℃ / min. The temperature is slowly cooled to below 80℃, and then cooled to below 60℃ along with the furnace.

[0054] Comparative Example 1 The comparative example is the same as that in Example 1, except that the amount of curing agent used is 10 parts, and the rest is the same as in Example 1.

[0055] Comparative Example 2 The comparative example is the same as that in Example 1, except that the amount of sheet-like inorganic filler used is 35 parts, and the rest is the same as in Example 1.

[0056] Comparative Example 3 This comparative example refers to the content of Example 1, except that the calcination temperature in the filler pretreatment step is 300°C, and the rest is the same as in Example 1.

[0057] Comparative Example 4 The comparative example refers to the content of Example 1, except that in the step curing step, the curing temperature of the first stage is 120°C, and the rest is the same as Example 1.

[0058] Comparative Example 5 The comparative example refers to the content of Example 1, except that in the step curing step, the pressure applied in the first stage of curing is 0.1 MPa, and the rest is the same as in Example 1.

[0059] Comparative Example 6 The comparative example refers to the content of Example 1, except that the cooling rate in the post-processing step is 2℃ / min, and the rest is the same as Example 1.

[0060] Performance testing Sample preparation: Insulating directional wheel samples were prepared according to the methods described in Examples 1-3 and Comparative Examples 1-6. Five samples of the same specifications were prepared for each example or comparative example for subsequent performance testing. All samples were placed in a standard laboratory environment at 23°C and 50% relative humidity for 24 hours before testing.

[0061] Arc resistance test: First, the insulating layer on the surface of the insulating directional wheel sample is cut into standard-sized test pieces. After cleaning and drying, the pieces are placed between the two electrodes of the arc resistance tester. A high-voltage current is applied according to the standard requirements, and the total time from the generation of the arc until carbonization, conductivity, or breakdown of the insulating material surface is recorded. This is the arc resistance value. The higher the value, the better the arc resistance performance of the material. Test standard: ASTM D495 - "Test method for solid insulating materials to withstand high voltage, low current arc discharge".

[0062] Bending strength and bending modulus test: First, insulating material is cut from the insulating directional wheel sample and processed into a long strip test bar of specified dimensions; the test bar is placed on the support of the universal testing machine, and a three-point bending method is used to apply a load at a constant rate until the test bar breaks. The testing system automatically records the load-displacement curve and calculates the bending strength and bending modulus of the material: Test standard: ISO 178 - "Determination of bending properties of plastics".

[0063] Heat distortion temperature test: First, the insulating material is processed into a rectangular strip of standard size and placed horizontally in the heat medium of the heat distortion tester. A specified constant load is applied to its center position. The temperature is increased at a uniform rate, and the temperature at which the strip bends and deforms to a specific standard deflection is recorded. This temperature is the heat distortion temperature. The higher the heat distortion temperature, the better the thermal stability of the material. Test standard: ISO75-2 - Determination of load distortion temperature of plastics - Part 2: Plastics and hard rubber.

[0064] Thermal conductivity and linear expansion coefficient testing: First, using a thermal conductivity analyzer, the insulating material sample is placed between two flat plate sensors, and the thermal conductivity of the material is calculated by measuring the temperature gradient under a certain heat flux. Then, using a thermomechanical analyzer, a sample of known length is heated under programmed temperature control, and the change in its length with temperature is accurately measured to calculate the linear expansion coefficient. Test standards: Thermal conductivity refers to ASTM E1461; linear expansion coefficient refers to ASTM E228.

[0065] Microstructural analysis by scanning electron microscopy: First, the insulating directional wheel sample was brittlely fractured along the direction perpendicular to the insulating layer, and the fracture surface was sputtered with gold to increase conductivity; then, the treated sample was placed under a scanning electron microscope, and the morphology of the fracture surface was observed at different magnifications, paying attention to the arrangement of inorganic fillers, the interface bonding between resin and fillers, and whether there are defects such as pores, cracks or delamination.

[0066] Table 1:

[0067] Table 2

[0068] Example Conclusion As can be seen from Examples 1-3 and Comparative Example 1, and Tables 1 and 2, an appropriate amount of curing agent is the basis for forming a dense, highly cross-linked three-dimensional network structure. When the amount of curing agent is insufficient, the resin matrix cannot be fully cross-linked, resulting in a loose internal structure and increased defects in the cured product, and deterioration of the product's mechanical strength, heat resistance, and electrical insulation properties.

[0069] As can be seen from Examples 1-3 and Comparative Example 2, and from Tables 1 and 2, a sufficient amount of sheet-like inorganic filler is the key to improving the overall performance of composite materials. The sheet-like filler forms a reinforcing skeleton and a shielding barrier in the matrix. Insufficient filler will weaken this reinforcement and barrier effect, resulting in a decrease in the stiffness, strength, dimensional stability and arc resistance of the product.

[0070] As can be seen from Examples 1-3 and Comparative Example 3, and Tables 1 and 2, calcination activation treatment of the filler is a prerequisite for achieving good interfacial bonding between the filler and the resin. Insufficient calcination temperature will lead to insufficient activation of hydroxyl groups on the surface of the filler, making it difficult to react with the coupling agent, which in turn results in weak interfacial bonding between the filler and the resin, creating interfacial gaps, which become weak links in performance and affect the mechanical properties and thermal stability of the product.

[0071] As can be seen from Examples 1-3 and Comparative Example 4, and Tables 1 and 2, the stepped curing regime can affect the control of reaction rate, reduce internal stress and ensure curing quality. Excessively high initial curing temperature will cause the curing reaction to be too fast, resulting in the freezing of molecular chains, the inability to release internal stress and the formation of microcracks, which will produce defects, thereby damaging the mechanical integrity, electrical insulation performance and thermal stability of the product.

[0072] Based on Examples 1-3 and Comparative Example 5, and in conjunction with Tables 1 and 2, it can be seen that applying appropriate pressure in the early stage of curing has a positive effect on eliminating air bubbles and compacting the structure; insufficient pressure cannot effectively promote resin flow and expel air, resulting in pores inside the composite material and insufficient density of the structure, thereby reducing the compactness, mechanical strength and heat resistance of the product.

[0073] As can be seen from Examples 1-3 and Comparative Example 6, and Tables 1 and 2, controlling the cooling rate after curing can affect and alleviate the internal stress caused by the difference in thermal shrinkage between the resin and the filler. An excessively fast cooling rate will generate large internal stress, leading to defects such as microcracks and interface debonding. These defects will weaken the mechanical properties, dimensional stability and long-term reliability of the product.

[0074] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A novel method for insulating the directional wheel of a submerged arc furnace platform, characterized in that, Includes the following steps: S1. Raw material preparation: Prepare the following raw materials in parts by weight: 100 parts modified epoxy resin matrix, 20-35 parts curing agent, 50-80 parts flake inorganic filler, 5-15 parts toughening agent and 1-3 parts coupling agent. S2. Pretreatment of filler: The sheet-like inorganic filler is placed in a high-temperature furnace and calcined at 450~550℃ for 60~120 minutes to obtain activated filler. After cooling, the activated filler is placed in an ethanol solution containing a portion of coupling agent. S3. Mixing and dispersing: The modified epoxy resin matrix from step S1, the activated filler, toughening agent and remaining coupling agent obtained from step S2 are put into a mixing tank and stirred at 300-500 rpm for 40-90 minutes under the conditions of 60-80℃ and vacuum degree of -0.08 to -0.095MPa to obtain a uniform resin mixture. S4. Adding curing agent and degassing: Add the curing agent from step S1 to the resin mixture obtained in step S3, stir at 150-250 rpm for 15-30 minutes at 40-50℃, and then let it stand under vacuum of -0.09--0.1MPa for 20-40 minutes to degas, and obtain a castable insulating slurry. S5. Mold preheating and casting: The surface of the directional wheel metal core is sandblasted to remove rust and preheated to 70~90℃. The preheated metal core is placed into a mold preheated to 80~100℃. Then, the pourable insulating slurry obtained in step S4 is poured into the mold cavity to completely cover the metal core. S6. Step Curing: Place the mold that has been poured in step S5 into a curing oven and perform the following steps in sequence: First stage curing: hold at 85~95℃ for 2~4 hours; Second stage curing: raise the temperature to 120~130℃ at a rate of 0.5~1℃ / min and hold for 3~5 hours; Third stage curing: raise the temperature to 150~160℃ at a rate of 1~2℃ / min and hold for 2~3 hours. S7. Post-processing and machining: After curing in step S6, the mold is cooled and demolded to obtain the insulating directional wheel blank. It is then machined to the specified dimensions to obtain the final insulating directional wheel product.

2. The novel method for insulating the directional wheel of a submerged arc furnace platform according to claim 1, characterized in that, In step S1, the sheet-like inorganic filler is muscovite powder or sericite powder that has undergone flake treatment, with a particle size D50 controlled at 15~45μm and a diameter-to-thickness ratio greater than 50.

3. The novel method for insulating the directional wheel of a submerged arc furnace platform according to claim 1, characterized in that, The modified epoxy resin matrix in step S1 is phenolic modified epoxy resin or organosilicon modified epoxy resin.

4. The novel method for insulating the directional wheel of a submerged arc furnace platform according to claim 1, characterized in that, The toughening agent is carboxylated nitrile rubber; the curing agent is methyltetrahydrophthalic anhydride or methylnadic anhydride.

5. The novel method for insulating the directional wheel of a submerged arc furnace platform according to claim 1, characterized in that, In step S2, after calcination, the activated filler is naturally cooled to below 80°C, and then immersed in an ethanol solution containing 50% to 70% of the total coupling agent for wet surface modification. The modification time is 20 to 40 minutes, and then it is dried to obtain the surface-modified activated filler for use in step S3.

6. The novel method for insulating the directional wheel of a submerged arc furnace platform according to claim 1, characterized in that, In step S3, the viscosity of the resin mixture is controlled to be 8000~15000 mPa·s.

7. The novel method for insulating the directional wheel of a submerged arc furnace platform according to claim 1, characterized in that, In step S4, along with the curing agent, a defoamer comprising 0.5% to 2% of the total mass of the resin mixture is also added. The defoamer is an organosilicon defoamer.

8. The novel method for insulating the directional wheel of a submerged arc furnace platform according to claim 1, characterized in that, In step S5, after the surface of the directional wheel metal core is sandblasted to remove rust, it is also cleaned and dried with an organic solvent, namely acetone or ethanol.

9. The novel method for insulating the directional wheel of a submerged arc furnace platform according to claim 1, characterized in that, In the first stage of curing in step S6, a pressure of 0.2~0.5MPa is applied to the mold.

10. The novel method for insulating the directional wheel of a submerged arc furnace platform according to claim 1, characterized in that, In step S7, the cooling rate is controlled to be no more than 1°C / min, and the temperature is slowly cooled to below 80°C, and then cooled to below 60°C with the furnace.

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