Boron-free long-life dry vibration material for induction furnace and preparation method of boron-free long-life dry vibration material

Abstract

The invention provides a boron-free long-life dry vibrating material for an induction furnace and a preparation method of the boron-free long-life dry vibrating material, and relates to the field of vibrating materials for induction furnaces. The preparation method of the boron-free long-life dry vibration material for the induction furnace comprises the following steps: preparing a complex-phase material, treating complex-phase particles, treating complex-phase micro powder and mixing. According to the boron-free long-life dry vibration material for the induction furnace, on the premise that boron is not contained, the long-term working stability of the dry vibration material is effectively improved while good mechanical strength, thermal shock resistance, high-temperature volume stability and steel slag permeation erosion resistance are obtained, and the service life of the dry vibration material is greatly prolonged.

Description

Technical Field

[0001] This invention relates to the field of induction furnace vibratory materials, and in particular to a boron-free long-life dry vibratory material for induction furnaces and its preparation method. Background Technology

[0002] As a crucial foundational industry within the industrial system, the steel industry provides essential materials for the development of various sectors. Currently, the steel industry is committed to reducing crude steel production capacity, optimizing smelting processes, and improving the quality of steel products, thereby promoting the research and development of high-end steel products required by industries such as shipbuilding, marine engineering, rail transportation, and aerospace.

[0003] With the continuous development of metallurgical technology, coreless medium-frequency induction furnaces (50-1000Hz) are widely used in non-ferrous metal smelting, steelmaking, and casting industries due to their advantages such as energy saving, high efficiency, flexible operation, rapid heating, low pollution, easy atmosphere control, and intermittent operation. As a crucial component of induction furnaces, the performance and service life of furnace lining refractory materials are of paramount importance to steel smelting and the quality of steel products.

[0004] In existing technologies, refractory materials for induction furnace linings are mainly classified into three categories according to their chemical properties: acidic refractories, neutral refractories, and basic dry ramming mixes. Among them, alumina-magnesia neutral dry ramming mixes are widely used in the iron and steel smelting industry due to their characteristics such as being boron-free, having high mechanical strength, good thermal shock resistance, good high-temperature volume stability, good erosion and impermeability resistance, and being environmentally friendly.

[0005] Currently, a certain amount of manganese (Mn) is added to high-quality special steels. This not only deoxidizes and reduces sulfur, improving the strength and hardness of the steel and its cold brittleness, but also enhances its wear resistance, toughness, weldability, and corrosion resistance. Therefore, this type of high-quality special steel is widely used in specialized fields such as marine engineering and energy chemicals. However, under the smelting environment of medium-high manganese steel, the service life of induction furnace lining materials, mainly composed of alumina-magnesia neutral dry vibrating material, is significantly reduced. This is primarily due to the strong diffusion and penetration ability of Mn in the molten steel within the dry vibrating material. Simultaneously, Mn is oxidized to MnO at the interface between the steel and refractory material, forming a large amount of liquid phase with the main component, Al2O3. Furthermore, it can form low-melting phases with non-major components in the matrix fine powder, ultimately causing rapid damage to the furnace lining material and severely affecting the quality of the prepared steel.

[0006] To address the aforementioned technical problems, many researchers have attempted to solve them by introducing auxiliary materials such as sintering-promoting additives to improve the density of dry vibratory materials, but with limited success. Therefore, this paper proposes a boron-free, long-life dry vibratory material for induction furnaces. This material, without the presence of boron, achieves good mechanical strength, thermal shock resistance, high-temperature volume stability, and resistance to steel slag penetration and erosion, while effectively improving the long-term working stability of the dry vibratory material and significantly extending its service life. This has significant technical importance and research value. Summary of the Invention

[0007] To address the technical problems existing in the prior art, this invention provides a method for preparing boron-free, long-life dry vibratory ballast for induction furnaces. The prepared dry vibratory ballast, without the presence of boron, achieves good mechanical strength, thermal shock resistance, high-temperature volume stability, and resistance to steel slag penetration and erosion, while effectively improving the long-term working stability and significantly extending its service life. This invention also provides boron-free, long-life dry vibratory ballast for induction furnaces prepared using this method.

[0008] To solve the above technical problems, the technical solution adopted by the present invention is as follows: A method for preparing a boron-free long-life dry vibrating material for an induction furnace includes the following steps: preparing a multiphase material, treating multiphase particles, treating multiphase micro powder, and mixing the materials. The method for preparing the multiphase material is as follows: Yb₂Si₂O₇ powder, Gd₂Si₂O₇ powder, and mullite powder are ball-milled until uniform, dried, and then sintered at 1350-1380℃ to obtain Yb₂Si₂O₇ with 0.8 < x ≤ 1. 2-x Gd x Si2O7 / mullite multiphase sintered body, after being crushed and ground, yields Yb. 2-x Gd x Si2O7 / mullite multiphase particles, Yb 2-x Gd x Si2O7 / mullite multiphase powder; The method for processing the multiphase particles is as follows: Yb 2-x Gd x Si2O7 / mullite multiphase particles, silica sol and deionized water are mixed, vacuum impregnated and the solid particles are collected; the solid particles are dried and calcined to obtain modified multiphase particles. The method for treating the multiphase micro powder is as follows: Yb 2-x Gd x After Si2O7 / mullite multiphase micro powder, zircon powder and silica sol were ball-milled evenly, the mixture was allowed to stand, spray-dried and calcined to obtain modified multiphase micro powder. The mixing method involves uniformly mixing corundum particles, modified multiphase particles, magnesia fine powder, magnesium oxide micro powder, activated alumina micro powder, modified multiphase micro powder, and aluminum-magnesium alloy powder to obtain boron-free long-life dry vibrating material for induction furnaces.

[0009] Preferably, in the preparation of the multiphase material, the molar ratio of Yb2Si2O7 powder, Gd2Si2O7 powder, and mullite powder is 42.5-47.5:42.5:10-15; Yb 2-x Gd x The particle size of the Si2O7 / mullite multiphase particles is 1.5-3 mm; Yb 2-x Gd x The particle size of the Si2O7 / mullite multiphase micro powder is <0.088 mm.

[0010] Preferably, in the preparation of the multiphase material, the ball milling speed is controlled at 400-500 rpm and the ball milling time is 2.5-3.5 h; The sintering time is 9-11 hours at 1350-1380℃.

[0011] Preferably, in the treatment of the multiphase particles, Yb is used. 2-x Gd x The weight ratio of Si2O7 / mullite multiphase particles, silica sol, and deionized water is 100:110-120:150-160. The silica sol contains 20-30 wt% nano-silica, and the nano-silica has a particle size of 10-20 nm.

[0012] Preferably, in the treatment of the multiphase particles, the vacuum degree of vacuum impregnation is 0.09-0.099 MPa, and the vacuum impregnation time is 6-7 h; Calcination is carried out in an anhydrous air atmosphere, with the temperature increased to 780-820℃ at a heating rate of 2.5-3℃ / min, and then held at that temperature for 1-2 hours.

[0013] Preferably, in the treatment of the multiphase micro powder, Yb is used. 2-x Gd x The weight ratio of Si2O7 / mullite multiphase powder, zircon powder, and silica sol is 100:9.5-10.5:24-26; The zircon powder has a ZrO2 content >66wt%, a SiO2 content <33wt%, and a particle size of 300-325 mesh. The silica sol contains 20-30 wt% nano-silica, and the nano-silica has a particle size of 10-20 nm.

[0014] Preferably, in the multiphase micro powder treatment, the ball milling speed is controlled at 150-200 rpm and the ball milling time is 2-3 hours; The settling temperature is room temperature, and the settling time is 3-4 hours; Calcination is carried out in an anhydrous air atmosphere, with the temperature increased to 780-820℃ at a heating rate of 1.5-2℃ / min, and then held at that temperature for 1-2 hours.

[0015] Preferably, the mixture uses the following raw materials in parts by weight: 50-70 parts corundum particles, 5-15 parts modified multiphase particles, 5-15 parts magnesia fine powder, 2-6 parts magnesium oxide micro powder, 1-5 parts activated alumina micro powder, 5-12 parts modified multiphase micro powder, and 0.2-0.8 parts aluminum-magnesium alloy powder.

[0016] Preferably, in the mixture, the Al2O3 content of the corundum particles is >99.5wt%; among the corundum particles used, particles with a diameter of 3-5mm account for 38-42wt% of all corundum particles, particles with a diameter of 1.5-3mm account for 30-32wt% of all corundum particles, and the remainder are particles with a diameter of 0.15-1.5mm. The MgO content of the fine magnesia powder is >96wt%, and the particle size of the fine magnesia powder is <0.088mm; The MgO content of the magnesium oxide micro powder is >98wt%, and the particle size of the magnesium oxide micro powder is <0.008mm; The activated alumina micro powder has an Al2O3 content > 99 wt% and a particle size < 0.005 mm. The Mg content of the aluminum-magnesium alloy powder is ≥20wt%, and the particle size of the aluminum-magnesium alloy powder is <0.1mm.

[0017] A boron-free, long-life dry vibratory feedstock for induction furnaces prepared using the aforementioned method.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The preparation method of the boron-free long-life dry vibrating material for induction furnace of the present invention firstly involves a solid-state reaction between Yb2Si2O7 powder, Gd2Si2O7 and mullite, and particle rearrangement and diffusion occur during sintering, further eliminating porosity, increasing density, and avoiding subsequent diffusion of impurity elements, forming a material with Yb2Si2O7 as the binder. 2-x Gd x Yb is composed of Si2O7 (0.8 < x ≤ 1) solid solution as the main phase and combined with the mullite phase. 2-x Gd x Si2O7 / mullite multiphase materials effectively optimize the thermal expansion matching between ytterbium-gadolinium silicate and mullite, thus optimizing and balancing the mechanical properties of the materials; Yb 2-x Gd xAfter Si2O7 / mullite multiphase material is made into corresponding multiphase particles and multiphase micro powders, the particles and micro powders are further processed to produce modified multiphase particles and modified multiphase micro powders, which further improves the material's resistance to penetration erosion and thermal shock. Finally, the modified multiphase particles, modified multiphase micro powders, aluminum-magnesium alloy powder and corundum particles are combined to produce dry vibratory feedstock. The various technical means work together synergistically to optimize the mechanical strength, thermal shock resistance, high-temperature volume stability and resistance to steel slag penetration erosion of dry vibratory feedstock without the presence of boron, and further improve the long-term working stability of dry vibratory feedstock and extend its service life.

[0019] (2) The boron-free long-life dry vibrating material for induction furnace of the present invention retains 88-91% of its strength after water cooling and hot shock at 1100℃ to 5℃; and the steel slag penetration erosion test conducted at 1600℃ using the static crucible method has a steel slag penetration erosion index ≤10%.

[0020] (3) The sintering linear change rate of the boron-free long-life dry vibrating material for induction furnace of the present invention is 0.24-0.30%, the room temperature elastic modulus after sintering is 33-38 GPa, the room temperature compressive strength after sintering is 103-108 MPa; and the average service life (i.e. the effective number of steelmaking cycles) can reach 111-116 times, and the number of thermal shock cycles from 1100℃ to room temperature is 21-23 times.

[0021] (4) The preparation method of the boron-free long-life dry vibrating material for induction furnace of the present invention has a simple process flow, the raw materials are easy to obtain, it can be prepared by conventional equipment, the process is easy to control, and it is conducive to industrial-scale production. Detailed Implementation

[0022] To provide a clearer understanding of the technical features, objectives, and effects of this invention, specific embodiments are now described. It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0023] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments of the present invention. As used herein, "first," "second," etc., are used to distinguish similar objects and are not used to describe a particular order or sequence. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0024] This invention provides a method for preparing boron-free long-life dry vibrating material for induction furnaces, comprising the following steps: preparing multiphase material, treating multiphase particles, treating multiphase micro powder, and mixing.

[0025] The method for preparing the multiphase material is as follows: Yb2Si2O7 powder, Gd2Si2O7 powder, and mullite (Al6Si2O7) are mixed together. 13 The powder was placed in a high-energy ball mill, using anhydrous ethanol as the milling medium and alumina ceramic balls as the grinding balls. The ball-to-material-to-liquid ratio was controlled at 6-7:1:0.6-0.65, and the milling speed was 400-500 rpm. After milling for 2.5-3.5 hours, the grinding balls were removed by sieving to obtain the milled material. The milled material was then placed in a constant temperature drying oven and dried at 80-85℃ for 10-12 hours. After drying, it was transferred to a high-temperature furnace, heated to 1350-1380℃, and sintered for 9-11 hours to obtain Yb 2-x Gd x Yb is composed of Si2O7 (0.8 < x ≤ 1) solid solution as the main phase and combined with the mullite phase. 2-x Gd x Si2O7 / mullite multiphase sintered body; the aforementioned multiphase sintered body was crushed and ground to obtain Yb particles with a particle size of 1.5-3 mm. 2-x Gd x Si2O7 / mullite multiphase particles, Yb with a particle size <0.088mm 2-x Gd x Si2O7 / mullite multiphase micro powder.

[0026] In the preparation of the multiphase material, Yb2Si2O7 powder, Gd2Si2O7 powder, and mullite (Al6Si2O7) were used. 13 The molar ratio of the powder is 42.5-47.5:42.5:10-15.

[0027] In this embodiment of the invention, Yb₂Si₂O₇ powder, Gd₂Si₂O₇ powder, and mullite (Al₆Si₂O₇) are used in the step of preparing the multiphase material. 13 Using Yb₂Si₂O₇ powder and Gd₂Si₂O₇ as raw materials, a solid-state reaction occurs with mullite. During sintering, particle rearrangement and diffusion occur, further eliminating porosity, increasing density, and preventing Mn diffusion, thus forming a structure with Yb₂Si₂O₇ as the raw material. 2-x Gd x Yb is composed of Si2O7 (0.8 < x ≤ 1) solid solution as the main phase and combined with the mullite phase. 2-x Gd x The Si2O7 / mullite composite material effectively optimizes the thermal expansion matching between ytterbium-gadolinium silicate and mullite, and optimizes the mechanical properties of the material. Then, the composite material is crushed to a predetermined particle size to obtain composite particles and composite micro powder.

[0028] The method for processing the multiphase particles is as follows: Yb 2-x Gd x Si2O7 / mullite multiphase particles, silica sol, and deionized water were mixed and stirred for 10-20 minutes. The mixture was then vacuumed at room temperature, with the vacuum level controlled at 0.09-0.099 MPa. After vacuum impregnation for 6-7 hours, excess liquid was removed, and the solid particles were collected. The solid particles were placed in a constant temperature drying oven and dried at 110-120℃ for 3-5 hours. They were then transferred to a calcination furnace and calcined at 780-820℃ at a heating rate of 2.5-3℃ / min in an anhydrous air atmosphere for 1-2 hours. After cooling to room temperature in the furnace, the particles were ground uniformly to obtain modified multiphase particles.

[0029] In the treatment of multiphase particles, the content of nano-silica in the silica sol is 20-30 wt%, and the particle size of nano-silica is 10-20 nm.

[0030] In the process of treating multiphase particles, Yb is used 2-x Gd x The weight ratio of Si2O7 / mullite multiphase particles, silica sol, and deionized water is 100:110-120:150-160.

[0031] In this embodiment of the invention, during the multiphase particle processing step, Yb is impregnated using a homologous phase silica sol. 2-x Gd x Si2O7 / mullite multiphase particles are processed, and silica sol is drawn into Yb using negative pressure. 2-x Gd x Within the internal pores or potential cracks of Si2O7 / mullite multiphase particles, after drying and calcination, the silica sol is transformed in situ into a glass phase, filling the pores, cracks, and other defects of the particles, and forming a silica glass layer on the particle surface. This improves the compatibility of the multiphase particles with other raw materials, while also preventing steel slag penetration and erosion, and buffering thermal stress.

[0032] The method for treating the multiphase micro powder is as follows: Yb 2-x Gd xAfter uniformly mixing Si2O7 / mullite multiphase micro powder and zircon powder to obtain a premix, the premix and silica sol are placed in a ball mill, controlling the ball-to-material ratio at 4-5:1 and the ball milling speed at 150-200 rpm. After ball milling for 2-3 hours, the grinding balls are removed by sieving to obtain the ball-milled material. After the ball-milled material is allowed to stand at room temperature for 3-4 hours, it is spray-dried, controlling the spray inlet temperature at 180-200℃ and the spray outlet temperature at 80-100℃ to obtain dried micro powder. The dried micro powder is transferred to a calcination furnace, and in an anhydrous air atmosphere, the temperature is raised to 780-820℃ at a heating rate of 1.5-2℃ / min. After holding at this temperature for 1-2 hours, the powder is cooled to room temperature with the furnace and ground uniformly to obtain modified multiphase micro powder.

[0033] In the process of treating the multiphase micro powder, Yb is used 2-x Gd x The weight ratio of Si2O7 / mullite multiphase powder, zircon powder, and silica sol is 100:9.5-10.5:24-26.

[0034] In the multiphase micro powder treatment, the content of nano-silica in the silica sol is 20-30 wt%, and the particle size of the nano-silica is 10-20 nm. The zircon powder is high-purity zircon powder, with a ZrO2 content >66wt%, a SiO2 content <33wt%, and a particle size of 300-325 mesh.

[0035] In this embodiment of the invention, in the multiphase micron powder processing step, zircon powder and Yb are combined through homogeneous reinforcement. 2-x Gd x The Si2O7 / mullite multiphase micro powder is uniformly compounded and adsorbed with silica sol, and then spray-dried to obtain dried micro powder. During the calcination process, the silica sol in the dried micro powder is completely transformed into a glass phase, filling the pores, cracks and other defects of the particles. Through the introduction of ZrO2 in zircon powder, the high-temperature volume stability is ensured while buffering thermal stress, further improving the resistance to steel slag penetration and thermal shock.

[0036] The mixing method is as follows: take the following raw materials in parts by weight: 50-70 parts of corundum particles, 5-15 parts of modified multiphase particles, 5-15 parts of magnesia fine powder, 2-6 parts of magnesium oxide micro powder, 1-5 parts of activated alumina micro powder, 5-12 parts of modified multiphase micro powder, and 0.2-0.8 parts of aluminum-magnesium alloy powder, mix the aforementioned raw materials evenly, and obtain boron-free long-life dry vibrating material for induction furnaces.

[0037] In the mixture, the corundum particles are sintered corundum particles or fused corundum particles, the Al2O3 content of the corundum particles is >99.5wt%, and the particle size range is 0.15-5mm; among the corundum particles used, particles with a particle size of 3-5mm account for 38-42wt%, particles with a particle size of 1.5-3mm account for 30-32wt%, and the remainder are particles with a particle size of 0.15-1.5mm.

[0038] In the mixture, the magnesia fine powder is sintered magnesia fine powder or fused magnesia fine powder, the MgO content of the magnesia fine powder is >96wt%, and the particle size of the magnesia fine powder is <0.088mm.

[0039] In the mixture, the MgO content of the magnesium oxide micro powder is >98wt%, and the particle size of the magnesium oxide micro powder is <0.008mm.

[0040] In the mixture, the Al2O3 content of the activated alumina micro powder is >99wt%, and the particle size of the activated alumina micro powder is <0.005mm.

[0041] In the mixture, the Mg content of the aluminum-magnesium alloy powder is ≥20wt%, and the particle size of the aluminum-magnesium alloy powder is <0.1mm.

[0042] In this embodiment of the invention, during the mixing step, corundum particles with a three-stage gradation are used to provide a high-strength skeleton. These particles are combined with modified multiphase particles, modified multiphase micro powder, aluminum-magnesium alloy powder, and other raw materials to optimize the mechanical strength, thermal shock resistance, high-temperature volume stability, and resistance to steel slag penetration and erosion of the dry vibrating material, without the presence of boron. This further improves the long-term working stability of the dry vibrating material and extends its service life.

[0043] This invention also provides a boron-free, long-life dry vibratory feedstock for induction furnaces prepared using the aforementioned method. In subsequent applications, the aluminum-magnesium alloy powder in this boron-free, long-life dry vibratory feedstock generates a certain liquid phase at medium and low temperatures, and this alloy liquid phase can also react with Yb. 2-x Gd x The Si2O7 / mullite multiphase material produces an alloy liquid phase, which is beneficial for improving the sintering strength and density of the material at medium and low temperatures. Furthermore, this alloy liquid phase gradually transforms into a solid solution in high-temperature environments, without affecting the material's high-temperature performance. Simultaneously, when the dry vibratory feedstock is used in high-temperature conditions (such as 1600℃), the Yb content in the modified multiphase particles and modified multiphase micropowder of the dry vibratory feedstock... 2-x Gd x Si2O7 solid solution can undergo crystal transformation and toughening, and Yb 2- x Gd xThe combined action of Si2O7 solid solution and mullite phase produces appropriate liquid phase self-repair for cracks, which not only gives dry vibratory feedstock good resistance to steel slag penetration and erosion during high-temperature service, but also improves the material's thermal shock resistance, high-temperature volume stability and long-term working stability, thereby effectively extending its overall service life.

[0044] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described below in conjunction with some specific embodiments.

[0045] Example 1 This embodiment provides a method for preparing boron-free long-life dry vibratory feedstock for induction furnaces, the specific steps of which are as follows: 1. Preparation of multiphase materials Yb2Si2O7 powder, Gd2Si2O7 powder, and mullite (Al6Si2O7) were mixed. 13 The powder was placed in a high-energy ball mill, using anhydrous ethanol as the milling medium and alumina ceramic balls as the grinding balls. The ball-to-material-to-liquid ratio was controlled at 6:1:0.6, and the milling speed was 400 rpm. After milling for 2.5 hours, the grinding balls were removed by sieving, and the milled material was obtained. The milled material was placed in a constant temperature drying oven and dried at 80℃ for 10 hours. Then, it was transferred to a high-temperature furnace, heated to 1380℃, and sintered for 9 hours to obtain Yb 2-x Gd x Yb is composed of Si2O7 (0.8 < x ≤ 1) solid solution as the main phase and combined with the mullite phase. 2-x Gd x Si2O7 / mullite multiphase sintered body; the aforementioned multiphase sintered body was crushed and ground to obtain Yb particles with a particle size of 2 mm. 2-x Gd x Si2O7 / mullite multiphase particles, Yb with a particle size of 0.06 mm 2-x Gd x Si2O7 / mullite multiphase micro powder.

[0046] Among them, Yb2Si2O7 powder, Gd2Si2O7 powder, and mullite (Al6Si2O) 13 The molar ratio of the powder is 42.5:42.5:15.

[0047] 2. Treatment of multiphase particles Yb 2-x Gd xSi2O7 / mullite multiphase particles, silica sol, and deionized water were mixed and stirred for 10 min. The mixture was then vacuumed at room temperature with a vacuum level of 0.09 MPa for 7 h. After vacuum impregnation, excess liquid was removed, and the solid particles were collected. The solid particles were placed in a constant temperature drying oven and dried at 110 °C for 5 h. They were then transferred to a calcination furnace and heated to 780 °C at a heating rate of 2.5 °C / min in an anhydrous air atmosphere. After calcination for 1.5 h, the mixture was cooled to room temperature with the furnace and ground uniformly to obtain modified multiphase particles.

[0048] The silica sol contains 25 wt% nano-silica, and the nano-silica has a particle size of 10 nm.

[0049] Yb 2-x Gd x The weight ratio of Si2O7 / mullite multiphase particles, silica sol, and deionized water is 100:110:150.

[0050] 3. Multiphase micro powder treatment Yb 2-x Gd x After uniformly mixing Si2O7 / mullite multiphase micro powder and zircon powder to obtain a premix, the premix and silica sol are placed in a ball mill, with a ball-to-material ratio of 4:1 and a ball milling speed of 150 rpm. After ball milling for 3 hours, the grinding balls are removed by sieving to obtain the ball-milled material. After the ball-milled material is allowed to stand at room temperature for 3 hours, it is spray-dried with the spray inlet temperature controlled at 190℃ and the spray outlet temperature controlled at 90℃ to obtain dried micro powder. The dried micro powder is transferred to a calcination furnace and heated to 780℃ at a heating rate of 1.5℃ / min in an anhydrous air atmosphere. After holding at this temperature for calcination for 1.3 hours, it is cooled to room temperature with the furnace and ground uniformly to obtain modified multiphase micro powder.

[0051] Among them, Yb 2-x Gd x The weight ratio of Si2O7 / mullite multiphase powder, zircon powder, and silica sol is 100:9.5:24.

[0052] The silica sol contains 25 wt% nano-silica, and the nano-silica has a particle size of 10 nm.

[0053] The zircon powder is high-purity zircon powder, with a ZrO2 content of 66.7wt%, a SiO2 content of 32.1wt%, and a particle size of 325 mesh.

[0054] 4. Mixing Take the following raw materials in parts by weight: 60 parts corundum particles, 14 parts modified multiphase particles, 10 parts magnesia fine powder, 4 parts magnesium oxide micro powder, 3 parts activated alumina micro powder, 8.6 parts modified multiphase micro powder, and 0.4 parts aluminum-magnesium alloy powder. Mix the above raw materials evenly to prepare boron-free long-life dry vibrating material for induction furnaces.

[0055] The corundum particles are sintered corundum particles with an Al2O3 content of 99.6 wt% and a particle size range of 0.15-5 mm. Specifically, among the corundum particles used, particles with a particle size of 3-5 mm account for 40 wt%, particles with a particle size of 1.5-3 mm account for 31 wt%, and the remainder are particles with a particle size of 0.15-1.5 mm.

[0056] The magnesia fine powder is fused magnesia fine powder with an MgO content of 96.4 wt% and a particle size of 0.08 mm.

[0057] The magnesium oxide micro powder has an MgO content of 98.3 wt% and a particle size of 0.006 mm.

[0058] The activated alumina micro powder has an Al2O3 content of 99.2 wt% and a particle size of 0.004 mm.

[0059] The Mg content of the aluminum-magnesium alloy powder is 21wt%, and the particle size of the aluminum-magnesium alloy powder is 0.08mm.

[0060] This embodiment also provides a boron-free long-life dry vibratory feed for induction furnaces prepared using the aforementioned method.

[0061] Example 2 This embodiment provides a method for preparing boron-free long-life dry vibratory feedstock for induction furnaces, the specific steps of which are as follows: 1. Preparation of multiphase materials Yb2Si2O7 powder, Gd2Si2O7 powder, and mullite (Al6Si2O7) were mixed. 13 The powder was placed in a high-energy ball mill, using anhydrous ethanol as the milling medium and alumina ceramic balls as the grinding balls. The ball-to-material-to-liquid ratio was controlled at 6.5:1:0.63, and the ball milling speed was 450 rpm. After ball milling for 3 hours, the grinding balls were removed by sieving, and the ball-milled material was obtained. The ball-milled material was placed in a constant temperature drying oven and dried at 85℃ for 11 hours. Then, it was transferred to a high-temperature furnace, heated to 1380℃, and sintered for 11 hours to obtain Yb 2-x Gd x Yb is composed of Si2O7 (0.8 < x ≤ 1) solid solution as the main phase and combined with the mullite phase. 2-x Gd x Si2O7 / mullite multiphase sintered body; the aforementioned multiphase sintered body was crushed and ground to obtain Yb particles with a particle size of 2 mm.2-x Gd x Si2O7 / mullite multiphase particles, Yb with a particle size of 0.06 mm 2-x Gd x Si2O7 / mullite multiphase micro powder.

[0062] Among them, Yb2Si2O7 powder, Gd2Si2O7 powder, and mullite (Al6Si2O) 13 The molar ratio of the powder is 42.5:42.5:15.

[0063] 2. Treatment of multiphase particles Yb 2-x Gd x Si2O7 / mullite multiphase particles, silica sol, and deionized water were mixed and stirred for 15 min. The mixture was then vacuumed at room temperature with a vacuum level of 0.095 MPa for 7 h. After vacuum impregnation, excess liquid was removed, and the solid particles were collected. The solid particles were placed in a constant temperature drying oven and dried at 115 °C for 4.5 h. They were then transferred to a calcination furnace and heated to 800 °C at a heating rate of 2.5 °C / min in an anhydrous air atmosphere. After calcination for 1.75 h, the mixture was cooled to room temperature with the furnace and ground uniformly to obtain modified multiphase particles.

[0064] The silica sol contains 25 wt% nano-silica, and the nano-silica has a particle size of 10 nm.

[0065] Yb 2-x Gd x The weight ratio of Si2O7 / mullite multiphase particles, silica sol, and deionized water is 100:116:153.

[0066] 3. Multiphase micro powder treatment Yb 2-x Gd x After uniformly mixing Si2O7 / mullite multiphase micro powder and zircon powder to obtain a premix, the premix and silica sol were placed in a ball mill. The ball-to-material ratio was controlled at 4.5:1, and the ball milling speed was 180 rpm. After ball milling for 2.75 h, the grinding balls were removed by sieving to obtain the ball-milled material. After the ball-milled material was allowed to stand at room temperature for 3.5 h, it was spray-dried. The spray inlet temperature was controlled at 190℃ and the spray outlet temperature was controlled at 90℃ to obtain dried micro powder. The dried micro powder was transferred to a calcination furnace and heated to 800℃ at a heating rate of 1.6℃ / min in an anhydrous air atmosphere. After holding at this temperature for calcination for 1.5 h, it was cooled to room temperature with the furnace and ground uniformly to obtain modified multiphase micro powder.

[0067] Among them, Yb 2-x Gd xThe weight ratio of Si2O7 / mullite multiphase powder, zircon powder, and silica sol is 100:10:25.

[0068] The silica sol contains 25 wt% nano-silica, and the nano-silica has a particle size of 10 nm.

[0069] The zircon powder is high-purity zircon powder, with a ZrO2 content of 66.7wt%, a SiO2 content of 32.1wt%, and a particle size of 325 mesh.

[0070] 4. Mixing Take the following raw materials in parts by weight: 55 parts corundum particles, 11 parts modified multiphase particles, 15 parts magnesia fine powder, 6 parts magnesium oxide micro powder, 2 parts activated alumina micro powder, 10.2 parts modified multiphase micro powder, and 0.8 parts aluminum-magnesium alloy powder. Mix the above raw materials evenly to prepare boron-free long-life dry vibrating material for induction furnaces.

[0071] The corundum particles are sintered corundum particles with an Al2O3 content of 99.6 wt% and a particle size range of 0.15-5 mm. Specifically, among the corundum particles used, particles with a particle size of 3-5 mm account for 40 wt%, particles with a particle size of 1.5-3 mm account for 31 wt%, and the remainder are particles with a particle size of 0.15-1.5 mm.

[0072] The magnesia fine powder is fused magnesia fine powder with an MgO content of 96.4 wt% and a particle size of 0.08 mm.

[0073] The magnesium oxide micro powder has an MgO content of 98.3 wt% and a particle size of 0.006 mm.

[0074] The activated alumina micro powder has an Al2O3 content of 99.2 wt% and a particle size of 0.004 mm.

[0075] The Mg content of the aluminum-magnesium alloy powder is 21wt%, and the particle size of the aluminum-magnesium alloy powder is 0.08mm.

[0076] This embodiment also provides a boron-free long-life dry vibratory feed for induction furnaces prepared using the aforementioned method.

[0077] Example 3 This embodiment provides a method for preparing boron-free long-life dry vibratory feedstock for induction furnaces, the specific steps of which are as follows: 1. Preparation of multiphase materials Yb2Si2O7 powder, Gd2Si2O7 powder, and mullite (Al6Si2O7) were mixed. 13The powder was placed in a high-energy ball mill, using anhydrous ethanol as the milling medium and alumina ceramic balls as the grinding balls. The ball-to-material-to-liquid ratio was controlled at 7:1:0.65, and the ball milling speed was 500 rpm. After ball milling for 2.5 hours, the grinding balls were removed by sieving, and the ball-milled material was obtained. The ball-milled material was placed in a constant temperature drying oven and dried at 85℃ for 10 hours. Then, it was transferred to a high-temperature furnace, heated to 1380℃, and sintered for 11 hours to obtain Yb 2-x Gd x Yb is composed of Si2O7 (0.8 < x ≤ 1) solid solution as the main phase and combined with the mullite phase. 2-x Gd x Si2O7 / mullite multiphase sintered body; the aforementioned multiphase sintered body was crushed and ground to obtain Yb particles with a particle size of 2 mm. 2-x Gd x Si2O7 / mullite multiphase particles, Yb with a particle size of 0.06 mm 2-x Gd x Si2O7 / mullite multiphase micro powder.

[0078] Among them, Yb2Si2O7 powder, Gd2Si2O7 powder, and mullite (Al6Si2O) 13 The molar ratio of the powder is 42.5:42.5:15.

[0079] 2. Treatment of multiphase particles Yb 2-x Gd x Si2O7 / mullite multiphase particles, silica sol, and deionized water were mixed and stirred for 20 min. The mixture was then vacuumed at room temperature with a vacuum level of 0.099 MPa for 6 h. After vacuum impregnation, excess liquid was removed, and the solid particles were collected. The solid particles were placed in a constant temperature drying oven and dried at 120 °C for 3 h. They were then transferred to a calcination furnace and heated to 820 °C at a heating rate of 3 °C / min in an anhydrous air atmosphere. After calcination for 1.2 h, the mixture was cooled to room temperature with the furnace and ground uniformly to obtain modified multiphase particles.

[0080] The silica sol contains 25 wt% nano-silica, and the nano-silica has a particle size of 10 nm.

[0081] Yb 2-x Gd x The weight ratio of Si2O7 / mullite multiphase particles, silica sol, and deionized water is 100:120:160.

[0082] 3. Multiphase micro powder treatment Yb 2-x Gd xSi2O7 / mullite multiphase micro powder and zircon powder were mixed evenly to obtain a premix. The premix and silica sol were placed in a ball mill, and the ball-to-material ratio was controlled at 5:1. The ball milling speed was 200 rpm, and the ball milling was carried out for 2 hours. After the ball milling was removed by sieving, the ball milled material was obtained. After the ball milled material was allowed to stand at room temperature for 4 hours, it was spray dried. The spray inlet temperature was controlled at 190℃ and the spray outlet temperature was controlled at 90℃ to obtain dried micro powder. The dried micro powder was transferred to a calcination furnace and heated to 820℃ at a heating rate of 2℃ / min in an anhydrous air atmosphere. After calcination for 1 hour, it was cooled to room temperature with the furnace and ground evenly to obtain modified multiphase micro powder.

[0083] Among them, Yb 2-x Gd x The weight ratio of Si2O7 / mullite multiphase powder, zircon powder, and silica sol is 100:10.5:26.

[0084] The silica sol contains 25 wt% nano-silica, and the nano-silica has a particle size of 10 nm.

[0085] The zircon powder is high-purity zircon powder, with a ZrO2 content of 66.7wt%, a SiO2 content of 32.1wt%, and a particle size of 325 mesh.

[0086] 4. Mixing Take the following raw materials in parts by weight: 65 parts corundum particles, 10 parts modified multiphase particles, 5 parts magnesia fine powder, 4.7 parts magnesium oxide micro powder, 5 parts activated alumina micro powder, 10 parts modified multiphase micro powder, and 0.3 parts aluminum-magnesium alloy powder. Mix the above raw materials evenly to prepare boron-free long-life dry vibrating material for induction furnaces.

[0087] The corundum particles are sintered corundum particles with an Al2O3 content of 99.6 wt% and a particle size range of 0.15-5 mm. Specifically, among the corundum particles used, particles with a particle size of 3-5 mm account for 40 wt%, particles with a particle size of 1.5-3 mm account for 31 wt%, and the remainder are particles with a particle size of 0.15-1.5 mm.

[0088] The magnesia fine powder is fused magnesia fine powder with an MgO content of 96.4 wt% and a particle size of 0.08 mm.

[0089] The magnesium oxide micro powder has an MgO content of 98.3 wt% and a particle size of 0.006 mm.

[0090] The activated alumina micro powder has an Al2O3 content of 99.2 wt% and a particle size of 0.004 mm.

[0091] The Mg content of the aluminum-magnesium alloy powder is 21wt%, and the particle size of the aluminum-magnesium alloy powder is 0.08mm.

[0092] This embodiment also provides a boron-free long-life dry vibratory feed for induction furnaces prepared using the aforementioned method.

[0093] Comparative Example 1 The technical solution of Example 2 is adopted, the difference being: (1) the addition of modified multiphase particles in the mixing step is omitted, and corundum particles are used to make up the weight of the modified multiphase particles; (2) the multiphase micro powder treatment step is omitted, and Yb 2- x Gd x Si2O7 / mullite multiphase micro powder can be used directly in equal amounts as a substitute for modified multiphase micro powder in the mixing process.

[0094] Comparative Example 2 The technical solution of Example 2 is adopted, the difference being: (1) the addition of modified multiphase micro powder in the mixing step is omitted, and the weight of modified multiphase micro powder is made up by equal amounts of magnesia fine powder and magnesium oxide micro powder in a weight ratio of 2:1; (2) the multiphase particle treatment step is omitted, and Yb 2-x Gd x Si2O7 / mullite multiphase particles can replace modified multiphase particles and be used directly in equal amounts in the mixing step.

[0095] Water-cooled thermal shock test, steel slag penetration erosion test, and thermal shock cycle test were conducted on the dry vibratory materials of each embodiment and comparative example. The sintering line change rate, room temperature elastic modulus after sintering, and room temperature compressive strength after sintering of the dry vibratory materials were detected. The average service life (i.e., effective steelmaking cycles) of the materials applied in steelmaking induction furnaces was also tested.

[0096] The water-cooled thermal shock test method involves heating the dry vibratory material to 1100℃, holding it at that temperature for 20 minutes, then immersing it in flowing deionized water at 5℃ for 3 minutes before calculating the strength retention rate of the dry vibratory material after the water-cooled thermal shock.

[0097] The steel slag penetration erosion test was conducted using the static crucible method. The test temperature was controlled at 1600℃. After holding at 1600℃ for 5 hours, the steel slag penetration erosion index was measured (i.e., the percentage of the area of ​​the crucible that was penetrated and eroded was calculated to the total cross-sectional area of ​​the crucible core).

[0098] The method for thermal shock cyclic testing is as follows: the dry vibratory material is heated to 1100℃, kept at that temperature for 20 minutes, and then placed in flowing deionized water at a temperature of 25℃ to cool down to 25℃; the aforementioned heating-cooling process is taken as one thermal shock cycle, and thermal shock cycles are continuously performed until the strength retention rate of the dry vibratory material is lower than 70%, and the number of thermal shock cycles with a strength retention rate ≥ 70% is recorded.

[0099] The method for calculating the linear change rate of sintering is to heat the dry vibrating material to 1600℃, hold it at that temperature for 9 hours, and then calculate the linear change rate of the dry vibrating material.

[0100] The specific test results are as follows:

[0101] It can be seen that the boron-free long-life dry vibrating material for induction furnaces in Examples 1-3 uses Yb2Si2O7 powder, Gd2Si2O7 powder, and mullite (Al6Si2O7) in the step of preparing the multiphase material. 13 Using Yb₂Si₂O₇ powder and Gd₂Si₂O₇ as raw materials, a solid-state reaction occurs with mullite. During sintering, particle rearrangement and diffusion occur, further eliminating porosity, increasing density, and preventing the diffusion of subsequent impurity elements (such as Mn), forming a structure with Yb₂Si₂O₇ as the raw material. 2-x Gd x Yb is composed of Si2O7 (0.8 < x ≤ 1) solid solution as the main phase and combined with the mullite phase. 2-x Gd x A Si2O7 / mullite multiphase material was used to effectively optimize the thermal expansion matching between ytterbium-gadolinium silicate and mullite, thus balancing the mechanical properties of the material. This multiphase material was then crushed to a predetermined particle size to obtain multiphase particles and multiphase micropowder. In the multiphase particle processing step, Yb was impregnated using a homologous silica sol via vacuum impregnation. 2-x Gd x Si2O7 / mullite multiphase particles are processed, and silica sol is drawn into Yb using negative pressure. 2-x Gd x Within the internal pores or potential cracks of Si2O7 / mullite multiphase particles, after drying and calcination, the silica sol transforms in situ into a glassy phase, filling the pores and cracks of the particles and forming a silica glass layer on the particle surface. This improves the compatibility of the multiphase particles with other raw materials while preventing steel slag penetration and erosion, and buffering thermal stress. Then, in the multiphase micronization process, zircon powder and Yb are integrated through homogeneous strengthening. 2-x Gd xThe Si2O7 / mullite multiphase micro powder is uniformly compounded and adsorbed with silica sol, and then spray-dried to obtain dried micro powder. During the calcination process, the silica sol in the dried micro powder is completely transformed into a glass phase, filling the pores, cracks and other defects of the particles. Through the introduction of ZrO2 in zircon powder, the high-temperature volume stability is ensured while buffering thermal stress, further improving the resistance to steel slag penetration and thermal shock. Finally, in the mixing step, three-stage graded corundum particles are used to provide a high-strength skeleton, which is combined with modified multiphase particles, modified multiphase micro powder, aluminum-magnesium alloy powder and other raw materials to form dry vibratory feedstock. The various technical means work together to optimize the mechanical strength, thermal shock resistance, high-temperature volume stability and steel slag penetration erosion resistance of the dry vibratory feedstock without boron, and further improve the long-term working stability of the dry vibratory feedstock and extend its service life. Specifically, the strength retention rate of the boron-free long-life dry vibratory feedstock in each embodiment can still reach 88-91% after water cooling thermal shock from 1100℃ to 5℃; the steel slag penetration erosion index of each embodiment is ≤10% when the static crucible method is used to conduct steel slag penetration erosion test at 1600℃; at the same time, the sintering line change rate, room temperature elastic modulus after sintering and room temperature compressive strength after sintering are good, the average service life can reach 111-116 cycles, and the number of thermal shock cycles from 1100℃ to room temperature is 21-23 cycles.

[0102] Comparative Example 1 uses corundum particles instead of modified multiphase particles, and omits the modification of Yb. 2-x Gd x After treatment with Si2O7 / mullite multiphase micro powder, the strength retention rate, thermal shock resistance and erosion penetration resistance of the prepared dry vibratory material were significantly deteriorated compared with Example 2. The average service life of the dry vibratory material was reduced to a certain extent. Meanwhile, due to the increase in the proportion of corundum particles in Comparative Example 1, its elastic modulus was slightly increased compared with Example 2.

[0103] Comparative Example 2 uses a combination of fine magnesia powder and magnesium oxide powder to replace the modified multiphase powder, and omits the modification of Yb. 2- x Gd x After treatment, the Si2O7 / mullite multiphase micro powder showed slightly better resistance to erosion and penetration than Comparative Example 1. However, compared with Example 2, its strength retention rate and thermal shock resistance were significantly deteriorated. Furthermore, the resistance to erosion and penetration and the average service life of the dry vibrating material were reduced to a certain extent.

[0104] Unless otherwise stated, all percentages used in this invention are mass percentages.

[0105] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a boron-free, long-life dry vibrating material for induction furnaces, characterized in that, The process includes the following steps: preparation of multiphase materials, treatment of multiphase particles, treatment of multiphase micro powders, and mixing. The method for preparing the multiphase material is as follows: Yb₂Si₂O₇ powder, Gd₂Si₂O₇ powder, and mullite powder are ball-milled until uniform, dried, and then sintered at 1350-1380℃ to obtain Yb₂Si₂O₇ with 0.8 < x ≤ 1. 2-x Gd x Si2O7 / mullite multiphase sintered body, after being crushed and ground, yields Yb. 2-x Gd x Si2O7 / mullite multiphase particles, Yb 2-x Gd x Si2O7 / mullite multiphase powder; The method for processing the multiphase particles is as follows: Yb 2-x Gd x Si2O7 / mullite multiphase particles, silica sol and deionized water are mixed, vacuum impregnated and the solid particles are collected; the solid particles are dried and calcined to obtain modified multiphase particles. The method for treating the multiphase micro powder is as follows: Yb 2-x Gd x After Si2O7 / mullite multiphase micro powder, zircon powder and silica sol were ball-milled evenly, the mixture was allowed to stand, spray-dried and calcined to obtain modified multiphase micro powder. The mixing method involves uniformly mixing corundum particles, modified multiphase particles, magnesia fine powder, magnesium oxide micro powder, activated alumina micro powder, modified multiphase micro powder, and aluminum-magnesium alloy powder to obtain boron-free long-life dry vibrating material for induction furnaces.

2. The method for preparing boron-free long-life dry vibrating material for induction furnaces according to claim 1, characterized in that, In the preparation of the multiphase material, the molar ratio of Yb2Si2O7 powder, Gd2Si2O7 powder, and mullite powder is 42.5-47.5:42.5:10-15. Yb 2-x Gd x The particle size of the Si2O7 / mullite multiphase particles is 1.5-3 mm; Yb 2-x Gd x The particle size of the Si2O7 / mullite multiphase micro powder is <0.088 mm.

3. The method for preparing boron-free long-life dry vibrating material for induction furnaces according to claim 1, characterized in that, In the preparation of the multiphase material, the ball milling speed is controlled at 400-500 rpm and the ball milling time is 2.5-3.5 h; The sintering time is 9-11 hours at 1350-1380℃.

4. The method for preparing boron-free long-life dry vibrating material for induction furnaces according to claim 1, characterized in that, In the treatment of the multiphase particles, Yb is used 2-x Gd x The weight ratio of Si2O7 / mullite multiphase particles, silica sol, and deionized water is 100:110-120:150-160. The silica sol contains 20-30 wt% nano-silica, and the nano-silica has a particle size of 10-20 nm.

5. The method for preparing boron-free long-life dry vibrating material for induction furnaces according to claim 1, characterized in that, In the treatment of the multiphase particles, the vacuum degree of vacuum impregnation is 0.09-0.099 MPa, and the vacuum impregnation time is 6-7 hours. Calcination is carried out in an anhydrous air atmosphere, with the temperature increased to 780-820℃ at a heating rate of 2.5-3℃ / min, and then held at that temperature for 1-2 hours.

6. The method for preparing boron-free long-life dry vibrating material for induction furnaces according to claim 1, characterized in that, In the treatment of the multiphase micro powder, Yb was used 2-x Gd x The weight ratio of Si2O7 / mullite multiphase powder, zircon powder, and silica sol is 100:9.5-10.5:24-26; The zircon powder has a ZrO2 content >66wt%, a SiO2 content <33wt%, and a particle size of 300-325 mesh. The silica sol contains 20-30 wt% nano-silica, and the nano-silica has a particle size of 10-20 nm.

7. The method for preparing boron-free long-life dry vibrating material for induction furnaces according to claim 1, characterized in that, In the process of treating the multiphase micro powder, the ball milling speed is controlled at 150-200 rpm and the ball milling time is 2-3 hours. The settling temperature is room temperature, and the settling time is 3-4 hours; Calcination is carried out in an anhydrous air atmosphere, with the temperature increased to 780-820℃ at a heating rate of 1.5-2℃ / min, and then held at that temperature for 1-2 hours.

8. The method for preparing boron-free long-life dry vibrating material for induction furnaces according to claim 1, characterized in that, The mixture uses the following raw materials in parts by weight: 50-70 parts corundum particles, 5-15 parts modified multiphase particles, 5-15 parts magnesia fine powder, 2-6 parts magnesium oxide micro powder, 1-5 parts activated alumina micro powder, 5-12 parts modified multiphase micro powder, and 0.2-0.8 parts aluminum-magnesium alloy powder.

9. The method for preparing boron-free long-life dry vibrating material for induction furnaces according to claim 1, characterized in that, In the mixture, the Al2O3 content of the corundum particles is >99.5wt%; among the corundum particles used, particles with a diameter of 3-5mm account for 38-42wt% of all corundum particles, particles with a diameter of 1.5-3mm account for 30-32wt% of all corundum particles, and the remainder are particles with a diameter of 0.15-1.5mm. The MgO content of the fine magnesia powder is >96wt%, and the particle size of the fine magnesia powder is <0.088mm; The MgO content of the magnesium oxide micro powder is >98wt%, and the particle size of the magnesium oxide micro powder is <0.008mm; The activated alumina micro powder has an Al2O3 content > 99 wt% and a particle size < 0.005 mm. The Mg content of the aluminum-magnesium alloy powder is ≥20wt%, and the particle size of the aluminum-magnesium alloy powder is <0.1mm.

10. A boron-free, long-life dry vibratory feedstock for induction furnaces prepared by the preparation method according to any one of claims 1-9.

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