Function gradient castable for blast-furnace casting house, blast-furnace casting house and preparation process of blast-furnace casting house

Abstract

The invention provides a functional gradient castable for a blast furnace casting house, the functional gradient blast furnace casting house and a preparation process of the functional gradient blast furnace casting house, and belongs to the technical field of blast furnace refractory materials. The problems that an existing gradient casting house is insufficient in interface bonding strength, poor in component adaptability and short in service life are solved. A five-layer gradient structure and an interface transition layer are adopted for cooperative regulation and control, and castable comprises a heat-insulation wear-resistant castable, a heat-insulation wear-resistant and anti-erosion interface transition material, an anti-erosion castable, an anti-erosion and high-temperature heat-insulation interface transition material and a high-temperature heat-insulation castable from outside to inside. The difference value of thermal expansion coefficients of adjacent layers is less than or equal to 0.3 * 10 <-6 > DEG C The interface transition layer is added with a composite reinforcing agent of ferro-silicon nitride and a titanate coupling agent, and the interface bonding strength is improved to 3.5 MPa or above. The corresponding blast furnace casting house adopts a corresponding five-layer structure, and the preparation process comprises the steps of raw material pretreatment, layered slurry preparation, interface pretreatment and layered pouring, and segmented maintenance and curing. The product provided by the invention has excellent thermal shock resistance (no crack after 50 times of water cooling circulation at 1100 DEG C), slag erosion resistance rate of less than or equal to 0.3 mm / h, service life prolonged to 18 months or more, simple and controllable preparation process, suitability for industrial production, and capability of guaranteeing long-period stable operation of a blast furnace.

Description

Technical Field

[0001] This invention relates to the field of blast furnace tapping area refractories, particularly to functional gradient refractories for blast furnace tapping areas, blast furnace tapping areas, and their preparation processes. Background Technology

[0002] The blast furnace tapping area is a critical part of blast furnace ironmaking production. Its working environment is extremely harsh, requiring it to withstand long-term high-temperature flame radiation exceeding 1500℃, erosion from molten iron and slag, thermal shock from periodic temperature fluctuations, and mechanical wear during charging and tapping. To meet the multiple performance requirements of the tapping area, including high-temperature resistance, erosion resistance, thermal shock resistance, and wear resistance, graded functional refractories have become a research hotspot and development direction for blast furnace tapping areas in recent years. This is because they can achieve a gradient distribution of different properties according to the varying needs of the service environment.

[0003] Existing design concepts for gradient functional blast furnace tapping areas primarily focus on a binary gradient structure of "outer layer wear-resistant + inner layer high-temperature / erosion-resistant," or a simple three-layer gradient structure of outer layer wear-resistant + inner layer high-temperature resistant + erosion-resistant. In terms of component selection, traditional refractory aggregates such as high-alumina, corundum, and silicon carbide are commonly used, combined with aluminate cement, silica fume, and alumina fume as binders. The performance gradient of the blast furnace tapping area is achieved by adjusting the ratio of aggregates to matrix in each layer. The manufacturing process is mostly layered casting, and curing employs a uniform room-temperature curing + high-temperature firing mode.

[0004] Although existing graded functional blast furnace tapping area castables have made some progress in improving individual properties, the following technical challenges still exist in practical applications: Insufficient interfacial bonding strength and poor compatibility of gradient components lead to gradient delamination and spalling failure of castables under the combined conditions of cyclic high-temperature impact, slag erosion, and mechanical wear at the blast furnace tapping area. This results in a service life that cannot meet the long-term stable operation requirements of large blast furnaces. Specifically, existing technologies only focus on optimizing the performance of each gradient layer itself, neglecting the component compatibility, thermal expansion coefficient matching, and interfacial bonding mechanism between adjacent gradient layers. On the one hand, significant differences in aggregate and matrix components between adjacent gradient layers lead to a mismatch in thermal expansion coefficients, generating substantial thermal stress at the interface during cyclic high-temperature fluctuations, which easily forms microcracks over long periods. On the other hand, existing technologies lack dedicated interfacial transition layers, or the transition layer components are poorly designed, failing to achieve a smooth transition and effective bonding between adjacent gradient layer components. This results in low interfacial bonding strength, making interlayer delamination and spalling highly susceptible to occur under slag erosion and mechanical wear. Furthermore, existing uniform curing processes cannot adapt to the different component characteristics of each gradient layer, further exacerbating interfacial defects and reducing the overall integrity of the gradient structure. Summary of the Invention

[0005] To solve the above technical problems: 1. This invention proposes a functional gradient castable for the blast furnace tapping area, comprising heat-insulating and wear-resistant castable, heat-insulating, wear-resistant and erosion-resistant interface transition material, erosion-resistant castable, erosion-resistant and high-temperature heat-insulating interface transition material, and high-temperature heat-insulating castable, wherein the heat-insulating and wear-resistant castable, heat-insulating, wear-resistant and erosion-resistant interface transition material, erosion-resistant castable, erosion-resistant and high-temperature heat-insulating interface transition material, and high-temperature heat-insulating castable are arranged in a gradient manner.

[0006] (1) The heat-insulating and wear-resistant castable includes corundum sand, silicon carbide sand, alumina powder, silica powder, aluminate cement, interface bonding enhancer, water-reducing agent, and defoamer; The corundum sand has a particle size of 5-10mm, an Al2O3 purity of ≥99%, and a mass percentage of 30-35%. The silicon carbide sand has a particle size of 3-5mm, a SiC purity of ≥98%, and a mass percentage of 20-25%. The alumina micro powder has a particle size ≤1μm, an Al2O3 purity ≥99%, and a mass percentage of 15-20%. The silicon micropowder has a particle size ≤0.5μm, SiO2 purity ≥98%, and a mass percentage of 5-8%. The aluminate cement is of type CA-70, and its mass percentage is 8-12%. The interface bonding enhancer is silicon nitride iron powder with a particle size ≤500nm and a mass percentage of 1-2%. The water-reducing agent is a polycarboxylate-based powdered water-reducing agent, specifically model PCA®-300P, with a mass percentage of 0.2-0.5%. The defoamer is an organosilicon, preferably methyl silicone oil, with a mass percentage of 0.1-0.3%.

[0007] (2) The heat-insulating, wear-resistant and erosion-resistant interface transition material includes corundum sand, silicon carbide sand, alumina powder, silica powder, aluminate cement, interface bonding enhancer, water-reducing agent, and defoamer; The corundum sand has a particle size of 2-5mm, an Al2O3 purity of ≥99%, and a mass percentage of 25-30%. The silicon carbide sand has a particle size of 1-3 mm, a SiC purity of ≥98%, and a mass percentage of 15-20%. The alumina micro powder has a particle size ≤1μm, an Al2O3 purity ≥99%, and a mass percentage of 20-25%. The silicon micropowder has a particle size ≤0.5μm, SiO2 purity ≥98%, and a mass percentage of 8-12%. The aluminate cement is of type CA-70 and has a mass percentage of 6-10%. The interface bonding enhancer is composed of silicon nitride iron powder and titanate coupling agent, with a mass ratio of silicon nitride iron powder to titanate coupling agent of 1:1. The average particle size of the interface bonding enhancer is ≤500nm, and the mass percentage is 1.5-2.5%. The water-reducing agent is a polycarboxylate-based powdered water-reducing agent, model PCA®-300P, with a mass percentage of 0.3-0.6%. The defoamer is an organosilicon, preferably methyl silicone oil, with a mass percentage of 0.1-0.3%.

[0008] (3) Anti-erosion castables include fused alumina sand, silicon nitride bonded silicon carbide particles, alumina powder, silica powder, aluminate cement, interface bonding reinforcing agent, water reducing agent, and defoamer; The fused alumina sand has a particle size of 5-15mm, an Al2O3 purity of ≥99.5%, and a mass percentage of 35-40%. The silicon nitride-bonded silicon carbide particles have a particle size of 3-8 mm; the silicon nitride-bonded silicon carbide particles are Si3N4 bonded to SiC, wherein the Si3N4 content is ≥20%; the mass percentage is 25-30%. The alumina micro powder has a particle size ≤1μm, an Al2O3 purity ≥99%, and a mass percentage of 12-18%. The silicon micropowder has a particle size ≤0.5μm, SiO2 purity ≥98%, and a mass percentage of 4-6%. The aluminate cement, model CA-80, has a mass percentage of 5-8%. The interface bonding enhancer is silicon nitride iron powder, with a mass percentage of 2-3%; The water-reducing agent is a polycarboxylate-based powdered water-reducing agent, model PCA®-400P, with a mass percentage of 0.4-0.7%. The defoamer is an organosilicon, preferably methyl silicone oil, with a mass percentage of 0.1-0.3%.

[0009] (4) The interface transition material for corrosion resistance and high temperature insulation includes fused alumina sand, silicon nitride bonded silicon carbide particles, alumina micro powder, silica micro powder, aluminate cement, interface bonding reinforcing agent, water reducing agent, and defoamer; The fused alumina sand has a mass percentage of 20-25%; the fused alumina Al2O3 has a purity of ≥99.5% and a particle size of 2-5mm; The silicon nitride-bonded silicon carbide particles have a mass percentage of 15-20%; the Si3N4 content in the silicon nitride-bonded silicon carbide particles is ≥20%, and the particle size is 1-3 mm; The alumina micro powder has a mass percentage of 22-28%; the alumina micro powder has an AL2O3 content of ≥99% and a particle size of ≤1μm; The silicon micro powder has a mass percentage of 6-10%; the purity of SiO2 in the silicon micro powder is ≥98%, and the particle size is ≤0.5μm; The aluminate cement has a mass percentage of 4-7%; the aluminate cement type is CA-80. The interface bonding reinforcing agent has a mass percentage of 1.5-2.5%; the interface bonding reinforcing agent is silicon nitride iron powder + titanate coupling agent, with a mass ratio of 1:1 and a particle size of ≤500nm. The water-reducing agent has a mass percentage of 0.3-0.6%; the water-reducing agent is a polycarboxylate powder water-reducing agent, model PCA®-400P; The defoamer has a mass percentage of 0.1-0.3%; the defoamer is an organosilicon, preferably methyl silicone oil.

[0010] (5) High-temperature heat-insulating castables include lightweight corundum aggregate, alumina hollow spheres, alumina powder, silica powder, aluminate cement, water-reducing agent, and defoamer; The lightweight corundum aggregate has a mass percentage of 30-35%; the lightweight corundum aggregate has an Al2O3 content ≥98%, a particle size of 5-12mm, and a bulk density ≤1.8g / cm³; The hollow alumina spheres have a mass percentage of 25-30%; the purity of the alumina hollow spheres (AL2O3) is ≥98%, and the particle size is 2-5 mm. The alumina micro powder has a mass percentage of 18-22%; the alumina micro powder (AL2O3) has a purity of ≥99% and a particle size of ≤1μm. The silicon micro powder has a mass percentage of 5-8%; the purity of SiO2 in the silicon micro powder is ≥98%, and the particle size is ≤0.5μm; The aluminate cement has a mass percentage of 6-10%; the aluminate cement type is CA-70. The water-reducing agent has a mass percentage of 0.2-0.5%; the water-reducing agent is a polycarboxylate powder water-reducing agent, model PCA®-300P; The defoamer has a mass percentage of 0.1-0.3%; the defoamer is an organosilicon, preferably methyl silicone oil.

[0011] This invention relates to a functional gradient castable for the blast furnace tapping area. Through "precise matching design of gradient components," based on the structure-property relationship between refractory material components and their coefficients of thermal expansion, it achieves a smooth transition in the thermal expansion properties of adjacent gradient layers in the following stages: heat-insulating and wear-resistant castable, heat-insulating and wear-resistant and erosion-resistant interface transition material, erosion-resistant castable, erosion-resistant and high-temperature heat-insulating interface transition material, and high-temperature heat-insulating castable. This fundamentally reduces interfacial thermal stress. Specifically: First, all graded materials use high-purity alumina-based raw materials (corundum sand, fused alumina sand, alumina micro powder, AL2O3≥98%) as core aggregates and matrix. These raw materials have stable low thermal expansion characteristics (thermal expansion coefficient of approximately 8.0-8.5×10 from room temperature to 1200℃). -6 To avoid abrupt expansion caused by the introduction of raw materials with low compatibility and high expansion differences (such as clay and magnesium materials), the temperature should be controlled at ℃. Simultaneously, silicon carbide raw materials with low expansion coefficients (SiC≥98%, thermal expansion coefficient 4.5-5.0×10⁻⁶) should be specifically selected. -6 (℃), by precisely adjusting the overall expansion level of each gradient material.

[0012] Secondly, the aggregate types, proportions and particle sizes of adjacent main layers (heat-insulating and wear-resistant castable / erosion-resistant castable / high-temperature heat-insulating castable) change in a gradient and continuous manner. The components of the heat-insulating and wear-resistant and erosion-resistant interface transition material and the erosion-resistant and high-temperature heat-insulating interface transition material directly inherit the core components of the adjacent main materials. Specifically, the heat-insulating and wear-resistant castable adopts "corundum sand (30-35%) + silicon carbide sand (20-25%)", while the heat-insulating, wear-resistant and anti-corrosion interface transition material is adjusted to "corundum sand (25-30%) + silicon carbide sand (15-20%)", and the aggregate particle size is reduced from 5-10mm / 3-5mm to 2-5mm / 1-3mm; the anti-corrosion castable adopts "electrofused corundum sand (35-40%) + silicon nitride-bonded silicon carbide particles (25-30%)", while the anti-corrosion and high-temperature heat-insulating interface transition material is adjusted to "electrofused corundum sand (20-25%) + silicon nitride-bonded silicon carbide particles (15-20%)", to achieve a gradual transition of the expansion coefficient rather than an abrupt change.

[0013] Third, synergistic control of the matrix is ​​achieved: the ratio of alumina micropowder (AL2O3≥99%) to silicon micropowder (SiO2≥98%) in each matrix layer is synergistically optimized, and the low expansion characteristics of silicon micropowder (thermal expansion coefficient 3.0-3.5×10) are utilized. -6 (℃) Further fine-tuning the expansion coefficient of the matrix phase to complement the expansion performance of the aggregate phase ensures the overall expansion uniformity of each layer and reduces the concentration of interfacial thermal stress.

[0014] 2. The present invention also proposes a blast furnace tapping area made of functional gradient castable refractory, which adopts a four-layer gradient structure, from the outside to the inside being a heat insulation and wear-resistant layer, an interface transition layer I, an anti-corrosion working layer, an interface transition layer II, and a high-temperature heat insulation layer; (1) The heat-insulating and wear-resistant layer is cast from heat-insulating and wear-resistant castable; the thickness is 30-50mm; The heat-insulating and wear-resistant castable includes corundum sand, silicon carbide sand, alumina powder, silica powder, aluminate cement, interface bonding enhancer, water-reducing agent, and defoamer; The corundum sand has a particle size of 5-10mm, an Al2O3 purity of ≥99%, and a mass percentage of 30-35%. The silicon carbide sand has a particle size of 3-5mm, a SiC purity of ≥98%, and a mass percentage of 20-25%. The alumina micro powder has a particle size ≤1μm, an Al2O3 purity ≥99%, and a mass percentage of 15-20%. The silicon micropowder has a particle size ≤0.5μm, SiO2 purity ≥98%, and a mass percentage of 5-8%. The aluminate cement is of type CA-70, and its mass percentage is 8-12%. The interface bonding enhancer is silicon nitride iron powder with a particle size ≤500nm and a mass percentage of 1-2%. The water-reducing agent is a polycarboxylate-based powdered water-reducing agent, specifically model PCA®-300P, with a mass percentage of 0.2-0.5%. The defoamer is an organosilicon, preferably methyl silicone oil, with a mass percentage of 0.1-0.3%.

[0015] The interface transition layer I is cast from a heat-insulating, wear-resistant, and erosion-resistant interface transition material; its thickness is 15-35mm. The heat-insulating, wear-resistant, and erosion-resistant interface transition material includes corundum sand, silicon carbide sand, alumina micro powder, silica micro powder, aluminate cement, interface bonding enhancer, water-reducing agent, and defoamer; The corundum sand has a particle size of 2-5mm, an Al2O3 purity of ≥99%, and a mass percentage of 25-30%. The silicon carbide sand has a particle size of 1-3 mm, a SiC purity of ≥98%, and a mass percentage of 15-20%. The alumina micro powder has a particle size ≤1μm, an Al2O3 purity ≥99%, and a mass percentage of 20-25%. The silicon micropowder has a particle size ≤0.5μm, SiO2 purity ≥98%, and a mass percentage of 8-12%. The aluminate cement is of type CA-70 and has a mass percentage of 6-10%. The interface bonding enhancer is composed of silicon nitride iron powder and titanate coupling agent, with a mass ratio of silicon nitride iron powder to titanate coupling agent of 1:1. The average particle size of the interface bonding enhancer is ≤500nm, and the mass percentage is 1.5-2.5%. The water-reducing agent is a polycarboxylate-based powdered water-reducing agent, model PCA®-300P, with a mass percentage of 0.3-0.6%. The defoamer is an organosilicon, preferably methyl silicone oil, with a mass percentage of 0.1-0.3%.

[0016] The anti-erosion working layer is cast from anti-erosion castable and has a thickness of 90-110mm. The anti-erosion castable includes fused corundum sand, silicon nitride-bonded silicon carbide particles, alumina micro powder, silica micro powder, aluminate cement, interface bonding reinforcing agent, water reducing agent, and defoamer; The fused alumina sand has a particle size of 5-15mm, an Al2O3 purity of ≥99.5%, and a mass percentage of 35-40%. The silicon nitride-bonded silicon carbide particles have a particle size of 3-8 mm; the silicon nitride-bonded silicon carbide particles are Si3N4 bonded to SiC, wherein the Si3N4 content is ≥20%; the mass percentage is 25-30%. The alumina micro powder has a particle size ≤1μm, an Al2O3 purity ≥99%, and a mass percentage of 12-18%. The silicon micropowder has a particle size ≤0.5μm, SiO2 purity ≥98%, and a mass percentage of 4-6%. The aluminate cement, model CA-80, has a mass percentage of 5-8%. The interface bonding enhancer is silicon nitride iron powder, with a mass percentage of 2-3%; The water-reducing agent is a polycarboxylate-based powdered water-reducing agent, model PCA®-400P, with a mass percentage of 0.4-0.7%. The defoamer is an organosilicon, preferably methyl silicone oil, with a mass percentage of 0.1-0.3%.

[0017] The interface transition layer II is cast from an anti-corrosion and high-temperature insulation interface transition material, with a thickness of 15-35mm. The erosion-resistant and high-temperature insulation interface transition material includes fused alumina sand, silicon nitride bonded silicon carbide particles, alumina micro powder, silica micro powder, aluminate cement, interface bonding reinforcing agent, water reducing agent, and defoamer; The fused alumina sand has a mass percentage of 20-25%; the fused alumina sand has an Al2O3 purity of ≥99.5% and a particle size of 2-5mm; The silicon nitride-bonded silicon carbide particles have a mass percentage of 15-20%; the Si3N4 content in the silicon nitride-bonded silicon carbide particles is ≥20%, and the particle size is 1-3 mm; The alumina micro powder has a mass percentage of 22-28%; the alumina micro powder has an AL2O3 content of ≥99% and a particle size of ≤1μm; The silicon micro powder has a mass percentage of 6-10%; the purity of SiO2 in the silicon micro powder is ≥98%, and the particle size is ≤0.5μm; The aluminate cement has a mass percentage of 4-7%; the aluminate cement type is CA-80. The interface bonding reinforcing agent has a mass percentage of 1.5-2.5%; the interface bonding reinforcing agent is silicon nitride iron powder + titanate coupling agent, with a mass ratio of 1:1 and a particle size of ≤500nm. The water-reducing agent has a mass percentage of 0.3-0.6%; the water-reducing agent is a polycarboxylate powder water-reducing agent, model PCA®-400P; The defoamer has a mass percentage of 0.1-0.3%; the defoamer is an organosilicon, preferably methyl silicone oil.

[0018] (5) The high-temperature insulation layer is cast from high-temperature insulation castable with a thickness of 50-70mm.

[0019] High-temperature insulating castables include lightweight corundum aggregate, hollow alumina spheres, alumina powder, silica powder, aluminate cement, water-reducing agent, and defoamer; The lightweight corundum aggregate has a mass percentage of 30-35%; the lightweight corundum aggregate has an Al2O3 content ≥98%, a particle size of 5-12mm, and a bulk density ≤1.8g / cm³; The hollow alumina spheres have a mass percentage of 25-30%; the purity of the alumina hollow spheres (AL2O3) is ≥98%, and the particle size is 2-5 mm. The alumina micro powder has a mass percentage of 18-22%; the alumina micro powder (AL2O3) has a purity of ≥99% and a particle size of ≤1μm. The silicon micro powder has a mass percentage of 5-8%; the purity of SiO2 in the silicon micro powder is ≥98%, and the particle size is ≤0.5μm; The aluminate cement has a mass percentage of 6-10%; the aluminate cement type is CA-70. The water-reducing agent has a mass percentage of 0.2-0.5%; the water-reducing agent is a polycarboxylate powder water-reducing agent, model PCA®-300P; The defoamer has a mass percentage of 0.1-0.3%; the defoamer is an organosilicon, preferably methyl silicone oil.

[0020] This invention addresses the technical problems of insufficient gradient interface bonding strength and poor synergistic compatibility of gradient components in existing technologies through a technical approach of "precise matching design of gradient components + synergistic regulation of interface transition layer," resulting in the following significant technical effects: 1. Significantly Improved Gradient Interface Bonding Strength: This invention achieves a smooth transition and effective bonding between adjacent gradient layer components by setting an interface transition layer between them. The transition layer components adopt a gradient gradient design, and interface bonding enhancers such as silicon nitride iron powder and titanate coupling agents are added. Combined with the use of interface treatment agents, this results in a smooth transition and effective bonding between components of adjacent gradient layers. Testing shows that the bonding strength of each gradient interface reaches over 3.5 MPa, an improvement of more than 30% compared to existing technologies, effectively preventing interlayer delamination and peeling.

[0021] 2. Optimized compatibility of gradient components: The aggregate and matrix components of each gradient layer are precisely matched and designed, and the difference in the coefficient of thermal expansion between adjacent gradient layers is controlled within 0.5 × 10⁻⁶. -6 Within ℃, it exhibits good chemical compatibility. Under cyclic high-temperature impact conditions, the thermal stress generated at the interface is significantly reduced, and the thermal shock stability is greatly improved (after 50 cycles of water cooling at 1100℃, no obvious cracks were observed). Meanwhile, the anti-corrosion working layer uses fused alumina and silicon nitride combined with silicon carbide composite aggregate, along with high-purity matrix powder, which has excellent resistance to slag erosion (erosion rate ≤0.5mm / h). The heat insulation and wear-resistant layer combines good wear resistance and heat insulation performance through a reasonable ratio of alumina and silicon carbide. The performance of each layer is synergistically adapted to meet the requirements of the complex working conditions of the iron tapping site.

[0022] 3. This invention also proposes a process for preparing a blast furnace tapping area, comprising the following steps: Step 1: Raw material pretreatment: Place the aggregates required for each gradient layer in an oven to dry. The aggregates include corundum sand, silicon carbide sand, fused corundum sand, silicon nitride-bonded silicon carbide particles, lightweight corundum aggregate, and alumina hollow spheres. Seal and store the interface bonding reinforcing agent, water reducing agent, and defoamer separately. Step 2: Preparation of each layer of slurry: According to the component ratio of each gradient layer, add the aggregate and matrix powder to a forced mixer and dry mix for 3-5 minutes. The matrix powder includes alumina micro powder, silica micro powder, and aluminate cement. Then add the interface bonding enhancer, water-reducing agent, and defoamer, and continue mixing for 2-3 minutes. Finally, add 6-8% of deionized water according to the total mass of each layer of materials, and mix for 5-8 minutes to obtain the casting slurry for each layer. Step 3: Layered casting: Using a mold, cast the layers in the following order: "high temperature insulation layer → interface transition layer II → anti-corrosion working layer → interface transition layer I → heat insulation and wear-resistant layer". After each layer is cast, vibrate to form the layer. The vibration frequency is 45-60Hz and the time is 2-5 minutes. Before casting adjacent gradient layers, apply a 5-8% concentration of titanate coupling agent ethanol solution to the surface of the lower layer and let it stand for 10-15 minutes. Step 4: Segmented curing and solidification: First, cure in an environment of 20-25℃ and relative humidity ≥80%; then place in a curing kiln, raise the temperature to 60℃ at 5℃ / h, and maintain the temperature for 12 hours, then raise the temperature again and maintain the temperature again; finally, fire in segments, first raise the temperature, then fire at a constant temperature, then raise the temperature again and fire at a constant temperature again, and then demold after naturally cooling to room temperature to obtain the finished product.

[0023] Specifically, it includes the following steps: Step 1: Raw material pretreatment: Place the aggregates required for each gradient layer in a 110℃ oven and dry for 24 hours; seal and store the interface bonding reinforcing agent, water reducing agent, and defoamer separately; the aggregates include corundum sand, silicon carbide sand, fused corundum sand, silicon nitride bonded silicon carbide particles, lightweight corundum aggregate, and alumina hollow spheres. Step 2: Preparation of each layer of slurry: According to the component ratio of each gradient layer, add the aggregate and matrix powder to the forced mixer and dry mix for 3-5 minutes; then add the interface bonding enhancer, water-reducing agent, and defoamer, and continue mixing for 2-3 minutes; finally, add 6-8% of deionized water according to the total mass of each layer of materials, and mix for 5-8 minutes to obtain the casting slurry for each layer; the matrix powder includes alumina micro powder, silica micro powder, and aluminate cement; Step 3: Layered Casting: Layered casting is performed using a mold, sequentially casting the high-temperature insulation layer, interface transition layer II, anti-corrosion working layer, interface transition layer I, and heat-insulating and wear-resistant layer. Vibration molding is performed after each layer is completed. Before casting adjacent gradient layers, an interface treatment agent is applied to the surface of the lower layer and allowed to stand for 10-15 minutes. The vibration molding frequency is 45-60 Hz, and the time is 2-5 minutes. The interface treatment agent is an ethanol solution of titanate coupling agent with a concentration of 5-8%. Step 4: Segmented curing and solidification: First, cure in an environment of 20-25℃ and relative humidity ≥80% for 24 hours; then place in a curing kiln, raise the temperature to 60℃ at 5℃ / h, and keep it at a constant temperature for 12 hours, then raise the temperature to 110℃ at 8℃ / h and keep it at a constant temperature for 24 hours; finally, fire in segments, first raise the temperature to 600℃ at 10℃ / h and keep it at a constant temperature for 10 hours, then raise the temperature to 1200℃ at 15℃ / h and keep it at a constant temperature for 8 hours, and then demold after naturally cooling to room temperature to obtain the finished product.

[0024] This invention, through a technical approach of "precise matching design of gradient components + synergistic control of interface transition layers," specifically addresses the technical challenge that existing technologies, with their uniform curing processes, cannot adapt to the different component characteristics of each gradient layer, further exacerbating interface defects and reducing the overall integrity of the gradient structure. This results in the following significant technical effects: 1. Extended service life and ensured stable blast furnace operation: The segmented curing and solidification process is adapted to the component characteristics of each gradient layer, ensuring that each layer is fully cured and formed, reducing interface defects, and improving the overall integrity of the gradient structure. In practical applications at large blast furnace tapping areas, the gradient functional castable prepared by this invention has a service life extended to more than 18 months, compared to approximately 12 months in existing technologies, representing an increase of more than 50%. This effectively reduces the number of maintenance operations, lowers production costs, and ensures long-term stable and efficient operation of the blast furnace. 2. The preparation process is simple and controllable, and easy to industrialize: The preparation process of this invention adopts conventional stirring and vibration molding equipment, and the segmented curing process parameters are clear. The operation is simple and controllable, and no special equipment is required. It is suitable for large-scale industrial production and has broad industrial application prospects. Detailed Implementation Example

[0025] This embodiment proposes a functional gradient castable for the blast furnace tapping area.

[0026] The functional gradient castable for the blast furnace tapping area in this embodiment has a five-layer structure, consisting of, from the outside to the inside: heat-insulating and wear-resistant castable, heat-insulating, wear-resistant and erosion-resistant interface transition material, erosion-resistant castable, erosion-resistant and high-temperature heat-insulating interface transition material, and high-temperature heat-insulating castable. The specific components of each layer (by mass percentage) are as follows: Thermal insulation and wear-resistant castable: 32% corundum sand (AL2O3 purity 99.2%, particle size 5-10mm), 22% silicon carbide sand (SiC purity 98.5%, particle size 3-5mm), 18% alumina micro powder (AL2O3 purity 99.1%, particle size 0.8μm), 6% silica micro powder (SiO2 purity 98.2%, particle size 0.4μm), 10% CA-70 aluminate cement, 1.5% silicon nitride iron powder (particle size 400nm), 0.3% PCA®-300P polycarboxylate superplasticizer, and 0.2% methyl silicone oil; Thermal insulation, wear resistance, and corrosion resistance interface transition material: 28% corundum sand (AL2O3 purity 99.2%, particle size 2-5mm), 18% silicon carbide sand (SiC purity 98.5%, particle size 1-3mm), 22% alumina micro powder (AL2O3 purity 99.1%, particle size 0.8μm), 10% silica micro powder (SiO2 purity 98.2%, particle size 0.4μm), 8% CA-70 aluminate cement, 2% silicon nitride iron powder + titanate coupling agent (mass ratio 1:1, particle size 400nm), 0.4% PCA®-300P polycarboxylate superplasticizer, 0.2% methyl silicone oil; Si3N4 Anti-erosion castable: 38% fused alumina sand (AL2O3 purity 99.6%, particle size 5-15mm), 28% silicon nitride-bonded silicon carbide particles (Si3N4 content 22%, particle size 3-8mm), 15% alumina micro powder (AL2O3 purity 99.1%, particle size 0.8μm), 5% silica micro powder (SiO2 purity 98.2%, particle size 0.4μm), 6% CA-80 aluminate cement, 2.5% silicon nitride iron powder (particle size 400nm), 0.5% PCA®-400P polycarboxylate superplasticizer, and 0.2% methyl silicone oil; Corrosion-resistant and high-temperature insulation interface transition material: fused alumina sand (AL2O3 purity 99.6%, particle size 2-5mm) 22%, silicon nitride-bonded silicon carbide particles (Si3N4 content 22%, particle size 1-3mm) 18%, alumina micro powder (AL2O3 purity 99.1%, particle size 0.8μm) 25%, silica micro powder (SiO2 purity 98.2%, particle size 0.4μm) 8%, CA-80 aluminate cement 6%, silicon nitride iron powder + titanate coupling agent (mass ratio 1:1, particle size 400nm) 2%, PCA®-400P polycarboxylate superplasticizer 0.4%, methyl silicone oil 0.2%; High-temperature insulating castable: 32% lightweight corundum aggregate (AL2O3 content 98.5%, particle size 5-12mm, bulk density 1.6g / cm³), 28% hollow alumina spheres (AL2O3 purity 98.5%, particle size 2-5mm), 20% alumina micro powder (AL2O3 purity 99.1%, particle size 0.8μm), 6% silica micro powder (SiO2 purity 98.2%, particle size 0.4μm), 8% CA-70 aluminate cement, 0.3% PCA®-300P polycarboxylate superplasticizer, and 0.2% methyl silicone oil.

[0027] A. Testing was conducted on the functional gradient castable for the blast furnace tapping area in Example 1 according to the corresponding national standards: The referenced national standards are as follows: ① Thermal expansion coefficient test (GB / T7320-2008), test the thermal expansion coefficient of each layer and the interface between adjacent layers; ②Interfacial bonding strength test (GB / T30874-2014, using the interfacial shear strength method); ③ Thermal shock stability test (GB / T30873-2014, 1100℃ water cooling cycle); ④ Slag erosion resistance test (simulated blast furnace slag, temperature 1500℃, erosion time 100h). ⑤ Abrasion resistance test at room temperature (GB / T18301-2001).

[0028] B. Raw material pretreatment: Place each layer of aggregate (corundum sand, silicon carbide sand, etc.) in a 110℃ oven and dry for 24 hours to remove moisture; seal the interface bonding reinforcing agent, water reducing agent, and defoamer for later use.

[0029] C. Slurry preparation: According to the above-mentioned component ratios for each layer, the aggregate and matrix powder (alumina micro powder, silica micro powder, aluminate cement) are added to a forced mixer and dry-mixed for 4 minutes. Then, the interface bonding enhancer, water-reducing agent, and defoamer are added and mixed for 3 minutes. Finally, 7% of the total mass of each layer of materials is added and mixed for 6 minutes to prepare a uniformly castable slurry for each layer.

[0030] D. Molding: Layered casting using molds is employed (only casting samples are prepared, not assembled into the tapping area structure). The thickness of each layer is consistent with the actual thickness of the subsequent tapping area. Specifically: The heat-insulating and wear-resistant layer is cast from heat-insulating and wear-resistant castable, and the thickness of the heat-insulating and wear-resistant layer is 40mm. Transition layer I is formed by casting a heat-insulating, wear-resistant, and erosion-resistant interface transition material, with a thickness of 25mm; The anti-erosion layer is formed by casting anti-erosion castable, and the thickness of the anti-erosion layer is 100mm; Transition layer II is formed by casting an interface transition material that is resistant to corrosion and provides high-temperature insulation. The thickness of transition layer II is 25mm.

[0031] A high-temperature insulation layer (60mm) is formed by casting high-temperature insulating castable. Vibration molding of each layer (frequency 55Hz, time 4min); E-segment curing: First, cure the product at 20-25℃ and relative humidity ≥80% for 24 hours; then place it in a curing kiln, raise the temperature to 60℃ at 5℃ / h, and maintain the temperature for 12 hours; then raise the temperature to 110℃ at 8℃ / h and maintain the temperature for 24 hours; finally, fire it in stages, first raising the temperature to 600℃ at 10℃ / h and maintaining the temperature for 10 hours, then raising the temperature to 1200℃ at 15℃ / h and maintaining the temperature for 8 hours, and then allowing it to cool naturally to room temperature before demolding to obtain the finished product.

[0032] F measures the thermal expansion coefficient of each shave layer, the bonding strength of each interface, the thermal shock stability, the resistance to slag erosion, and the wear resistance at room temperature, as follows: (1) The thermal expansion coefficient of each shave layer was measured, and the results were as follows: Thermal insulation and wear-resistant layer 7.2×10 -6 ℃, Thermal insulation, wear resistance and corrosion resistance interface transition material 6.9×10 -6 ℃, Anti-erosion castable 6.7×10 -6 ℃, Corrosion-resistant and high-temperature insulation interface transition material 6.4×10 -6 ℃, High-temperature insulation layer 6.1×10 -6 ℃; The difference in the coefficient of thermal expansion between adjacent layers is 0.3 × 10⁻⁶. -6 ℃, far lower than the existing technology's 1.8×10 -6 ℃; (2) The bonding strength of each interface was measured, and the results were as follows: The interface between the heat-insulating and wear-resistant layer and the transition layer I has a pressure of 3.8 MPa. The interface between transition layer II and high-temperature insulation layer is 3.6 MPa. Existing technologies with similar interfacial bonding strength only achieve 2.2 MPa; (3) Thermal shock stability was measured, and the results were as follows: After 50 cycles of water cooling at 1100℃, no microcracks were found in any layer or interface, and the integrity of the sample was maintained at 100%. Existing technology products showed interface microcracks after 28 cycles. (4) The resistance to slag erosion was measured, and the results were as follows: After 100 hours of slag erosion at 1500℃, the erosion rate of the erosion-resistant castable was 0.3 mm / h, with a sample mass loss rate of 1.3%; the erosion rate of the existing technology was 1.2 mm / h, with a mass loss rate of 9.8%. (5) The abrasion resistance at room temperature was measured, and the results were as follows: The wear of the heat insulation and wear-resistant layer is 0.8 g / cm², while the wear of similar materials in the prior art is 1.5 g / cm².

[0033] As can be seen from the experimental data of this embodiment, the functionally graded castable of this embodiment solves the technical problems of "large differences in the composition of adjacent gradient layers leading to mismatch in thermal expansion, low interfacial bonding strength, and easy peeling and spalling" in the prior art. The specific effects are as follows: The problem of thermal expansion mismatch was solved: the difference in the thermal expansion coefficients of adjacent layers was controlled within 0.3 × 10⁻⁶. -6 At ℃, the interfacial thermal stress is significantly reduced during the periodic high temperature rise and fall process, and there are no microcracks caused by thermal stress. The problem of low interfacial bonding strength has been solved: the interfacial bonding strength has been increased by more than 68%, and there is no interlayer peeling or flaking under the action of molten slag scouring and mechanical wear; Excellent overall performance: Its resistance to slag erosion and wear resistance are superior to existing technologies, providing core material support for the subsequent preparation of long-life blast furnace tapping sites.

[0034] Functional gradient castable for the blast furnace tapping area in this embodiment: Firstly, the thermal expansion is appropriately matched, achieving a smooth transition in the coefficient of thermal expansion and avoiding abrupt changes: each layer uses high-purity alumina-based raw materials (low thermal expansion characteristics), through a gradual change in aggregate ratio (32% corundum sand in the heat insulation and wear-resistant layer → 28% in the transition layer I) and a decrease in particle size (5-10mm → 2-5mm), combined with silica micropowder (coefficient of thermal expansion 3.2×10). -6 The matrix is ​​finely adjusted at ℃ to achieve a smooth transition of the coefficient of thermal expansion and avoid abrupt changes; Secondly, interface strengthening was carried out: a composite reinforcing agent of "silicon nitride + titanate coupling agent" was added to the transition layer. At high temperature, silicon nitride reacts with alumina and silica powder to generate a high-strength β-SiAlON ceramic bonding phase, which fills the interface voids. The titanate coupling agent connects inorganic aggregates and cement hydration products through chemical bonds, forming a dual reinforcement of "chemical bonding + physical anchoring", which improves the interface bonding strength. Third, it is erosion-resistant and wear-resistant: the erosion-resistant layer uses high-purity fused alumina and silicon carbide composite aggregate with high Si3N4 content silicon nitride. Both have excellent chemical stability and can resist slag erosion; the heat insulation and wear-resistant layer has a reasonable ratio of alumina and silicon carbide, which takes into account both hardness and structural density, and improves wear resistance. Example

[0035] This embodiment proposes a blast furnace tapping area prepared from functional gradient castable refractory.

[0036] (1) The blast furnace tapping area in this embodiment adopts a five-layer gradient structure, which is as follows from the outside to the inside: Thermal insulation and wear-resistant layer: cast from the thermal insulation and wear-resistant castable in Example 1, with a thickness of 40mm, mainly bearing mechanical wear and outer thermal insulation functions; Interface transition layer I (thermal insulation, wear resistance and erosion resistance transition): cast from the thermal insulation, wear resistance and erosion resistance interface transition material in Example 1, with a thickness of 25mm, which undertakes the function of interlayer component connection and interface strengthening; Anti-corrosion working layer: cast from the anti-corrosion castable in Example 1, with a thickness of 100mm, directly withstands the erosion of high-temperature molten iron and slag, and is the core functional layer; Interface transition layer II (anti-erosion and high-temperature insulation transition): cast from the anti-erosion and high-temperature insulation interface transition material in Example 1, with a thickness of 25mm, connecting the anti-erosion layer and the high-temperature insulation layer; High-temperature insulation layer: cast from the high-temperature insulation castable in Example 1, with a thickness of 60mm, to reduce the conduction of internal high temperature to the outside and protect the furnace structure.

[0037] The specific composition of each layer of castable is completely consistent with that in Example 1, ensuring that the components between layers are compatible and adaptable.

[0038] (2) Preparation process Sample preparation: According to the above-mentioned structural thickness, the castable and preparation process of Example 1 were used to cast the sample in layers in a mold simulating the blast furnace tapping area. The casting sequence of "high temperature insulation layer → transition layer II → anti-corrosion working layer → transition layer I → heat insulation and wear-resistant layer" was strictly followed. Before casting adjacent layers, a 5% titanate coupling agent ethanol solution was brushed on. After standing for 12 minutes, the upper layer was cast. The vibration molding parameters of each layer were the same as those in Example 1. The segmented curing process was the same, and a 1:10 scale blast furnace tapping area simulation sample was obtained. Conduct simulated service tests: ① High-temperature thermal shock cycle test: Simulate the periodic tapping conditions of the blast furnace tapping area, hold at 1500℃ for 2 hours (simulating tapping) → air cool at room temperature for 30 minutes (simulating shutdown), which is considered as 1 cycle, and a total of 50 cycles are performed; ② Simulated slag scouring test: Under a high temperature environment of 1500℃, blast furnace slag was continuously scouring the surface of the anti-erosion working layer at a flow rate of 0.8m / s for 100h. ③ Overall structural integrity inspection: After cyclic testing and scouring test, ultrasonic flaw detector is used to check whether there is peeling or cracks at the interlayer interface, and to measure the thickness change and mass loss of each layer. ④ Industrial trial verification: The blast furnace tapping field made with this gradient structure and material was applied to the 1200m³ large blast furnace tapping field of Nanjing Iron & Steel Co., Ltd., and the actual service life and failure conditions were recorded.

[0039] (3) Experimental data High-temperature thermal shock cycling: After 50 cycles, ultrasonic testing showed no peeling or cracks at the interfaces of each layer, and the structural integrity was 100%; after 25 cycles, the iron tapping field simulation sample prepared by existing technology showed through cracks at the interface and lost its integrity. Simulated slag erosion: After 100 hours of erosion, the thickness of the erosion-resistant working layer decreased by 3 mm, with an overall mass loss rate of 1.5%; the thickness of the sample from the tapping yard using existing technology decreased by 12 mm, with a mass loss rate of 10.2%. Industrial trial: It was used in the tapping area of ​​a 1200m³ blast furnace for 18.5 months without any interlayer peeling or spalling failures, and there was no obvious erosion or depression on the surface of the tapping area. During the same period, the existing technology tapping area was only used for 11.5 months before the risk of iron leakage appeared due to interface spalling, and it was necessary to shut down for maintenance.

[0040] This embodiment, using a functionally graded castable refractory for the blast furnace tapping area, solves the technical problems of existing technologies, such as "poor overall integrity of the gradient structure, easy peeling and spalling under high-temperature impact and slag erosion, and short service life." Specifically: First, it has excellent overall structural integrity: the five-layer gradient structure, through the coordinated control of the transition layer, has no interface cracks or peeling under periodic high temperature impact, which solves the core pain point of easy failure of existing technology structures; Second, it has strong resistance to erosion and scouring: the core anti-erosion layer can withstand long-term scouring by high-temperature molten slag, and the amount of wear is far lower than that of existing technologies. Third, the service life is significantly extended: the industrial trial life reaches 18.5 months, which is more than 60% higher than the existing technology, reducing the number of maintenance operations, lowering production costs, and ensuring the long-term stable operation of the blast furnace.

[0041] This embodiment describes a blast furnace tapping area prepared from functionally graded castable refractory. On the one hand, by gradually changing the composition of the transition layer, a smooth transition of performance from "heat insulation and wear resistance to corrosion resistance and high temperature insulation" is achieved, avoiding interface defects caused by direct connection of different functional layers and improving the deformation resistance of the overall structure of the iron tapping yard. Secondly, the SiAlON ceramic bonding phase generated by the composite reinforcing agent in the transition layer not only improves the interfacial bonding strength, but also disperses the thermal stress generated by high-temperature impact, avoiding crack propagation caused by stress concentration. Third, the thickness and performance of each layer can be precisely matched with service requirements. Specifically, the anti-corrosion layer is the thickest and bears the core corrosion. The lightweight corundum aggregate and alumina hollow spheres of the high-temperature insulation layer form a porous insulation structure, which reduces heat conduction, lowers the interface temperature difference, and further alleviates thermal stress. Example

[0042] This embodiment proposes a preparation process for blast furnace tapping areas using functionally graded castable refractory.

[0043] The preparation process in this embodiment includes four core steps: raw material pretreatment, preparation of each layer of slurry, layered casting and molding, and segmented curing and solidification. The specific parameters are as follows: Step 1: Raw material pretreatment: Place corundum sand, silicon carbide sand, fused corundum sand, silicon nitride-bonded silicon carbide particles, lightweight corundum aggregate, and alumina hollow spheres in a 110℃ oven and dry for 24 hours to remove moisture until the moisture content is ≤0.5%; silicon nitride iron powder, titanate coupling agent, PCA®-300P / 400P water-reducing agent, and methyl silicone oil are sealed and stored in a dry environment to avoid moisture absorption; Step 2: Preparation of each layer of slurry: According to the component ratio in Example 1, add the aggregate and matrix powder (alumina micro powder, silica micro powder, aluminate cement) of each layer to a JS500 forced mixer and dry mix for 4 minutes until uniformly mixed; add the interface bonding enhancer, water-reducing agent, and defoamer, and continue mixing for 3 minutes; add deionized water accounting for 7% of the total mass of each layer of materials, and mix for 6 minutes, controlling the slurry flowability to 180 mm (standard cone method) to obtain uniformly castable slurry for each layer; Step 3: Layered Casting and Molding: Using a customized blast furnace tapping mold, first pour a 60mm thick high-temperature insulation layer slurry, vibrating it (55Hz, 4min); then uniformly coat its surface with a 5% titanate coupling agent ethanol solution and let it stand for 12min; pour a 25mm thick interface transition layer II slurry, vibrating it (50Hz, 3min); apply the same interface treatment agent and let it stand for 12min; pour a 100mm thick anti-corrosion working layer slurry, vibrating it (55Hz, 4min); apply the interface treatment agent and let it stand for 12min; pour a 25mm thick interface transition layer I slurry, vibrating it (50Hz, 3min); apply the interface treatment agent and let it stand for 12min; finally, pour a 40mm thick heat-insulating and wear-resistant layer slurry, vibrating it (55Hz, 4min). Step 4: Segmented curing and solidification: After casting, cure at room temperature for 24 hours at 22℃ and 85% relative humidity; transfer to a curing kiln, heat to 60℃ at a rate of 5℃ / h, and cure at a constant temperature for 12 hours; then heat to 110℃ at a rate of 8℃ / h, and cure at a constant temperature for 24 hours to complete moisture evaporation; subsequently heat to 600℃ at a rate of 10℃ / h, and bake at a constant temperature for 10 hours; finally heat to 1200℃ at a rate of 15℃ / h, and bake at a constant temperature for 8 hours; allow to cool naturally to room temperature (cooling rate ≤10℃ / h), and demold to obtain the finished product from the blast furnace tapping area.

[0044] The parameters of the blast furnace tapping site and preparation process prepared using this embodiment were measured: the material parameters included: process parameter stability, interfacial bonding strength, thermal shock stability, structural porosity, and industrial trial life.

[0045] Process parameter monitoring: During the preparation process, key parameters of each step are recorded in real time: moisture content of raw materials after drying, slurry stirring time and fluidity, vibration frequency and time of each layer, curing temperature and time, calcination heating rate and isothermal time. A. Comparative experiment: A control group was set up. The control group adopted the existing "uniform curing and solidification process" (curing at 22℃ for 48 hours after pouring, and then directly heating to 1200℃ at a constant temperature for 12 hours). The other raw materials, component ratios, and pouring sequence were the same as in this embodiment. The control group adopted a traditional "three-layer gradient structure" (outer → inner): wear-resistant layer → corrosion-resistant layer → high-temperature insulation layer. The composition and proportions of the control group (by mass percentage) are as follows: 1) Outer wear-resistant layer (corresponding to the experimental group's "heat insulation and wear-resistant layer", thickness ≈ 40mm) Components Specifications mass percentage Key points (differences from the experimental group) Corundum Sand <![CDATA[The purity of Al2O3 is 99%, and the particle size is 5 - 10 mm]]> 40% The proportion was higher than that of the experimental group (32%). silicon carbide sand SiC purity 98%, particle size 3-5mm 20% The proportion was similar to that of the experimental group (22%). Alumina micro powder <![CDATA[The purity of Al2O3 is 99% and the particle size is 0.8 μm]]> 12% The proportion was lower than that of the experimental group (18%). Silica powder <![CDATA[SiO2 purity 98%, particle size 0.4μm]]> 5% The proportion was lower than that of the experimental group (6%). aluminate cement Model CA-70 16% The proportion was much higher than that of the experimental group (10%). Water reducing agent Traditional naphthalene-based water-reducing agents (non-polycarboxylate-based) 0.4% Replacement experimental group PCA®-300P Defoamer Methyl silicone oil (organosilicon) 0.2% Consistent with the experimental group Interface bonding enhancer - (Silicon nitride-free iron powder) 0% 2) Intermediate anti-corrosion layer (corresponding to the "anti-corrosion working layer" of the experimental group, thickness ≈ 100mm) Components Specifications mass percentage Key points (differences from the experimental group) fused alumina sand <![CDATA[The purity of Al2O3 is 99.5% and the particle size is 5 - 15 mm]]> 44% The proportion was higher than that of the experimental group (38%). ordinary silicon carbide particles SiC purity 98%, particle size 3-8mm (non-silicon nitride bonded) 24% Replace the experimental group with "silicon nitride-bonded silicon carbide particles" Alumina micro powder <![CDATA[The purity of Al2O3 is 99% and the particle size is 0.8μm]]> 12% The proportion was lower than that of the experimental group (15%). Silica powder <![CDATA[SiO2 purity 98%, particle size 0.4μm]]> 7% The proportion was higher than that of the experimental group (5%). aluminate cement Model CA-70 (non-experimental group CA-80) 10% The bonding strength is lower than that of CA-80 Water reducing agent Traditional naphthalene-based water-reducing agents (non-polycarboxylate-based) 0.6% Replacement experimental group PCA®-400P Defoamer Methyl silicone oil (organosilicon) 0.2% Consistent with the experimental group Interface bonding enhancer (Silicon nitride-free iron powder) 0% 3) Inner high-temperature insulation layer (corresponding to the experimental group's "high-temperature insulation layer", thickness ≈ 60mm) Components Specifications mass percentage Key points (differences from the experimental group) Lightweight corundum aggregate <![CDATA[Aluminum oxide content is 98%, particle size is 5 - 12 mm, bulk density is 1.7 g / cm³]]> 38% The proportion was higher than that of the experimental group (32%). Hollow alumina spheres <![CDATA[The purity of Al2O3 is 98%, and the particle size is 2 - 5 mm]]> 24% The proportion was lower than that of the experimental group (28%). Alumina micro powder <![CDATA[The purity of Al2O3 is 99% and the particle size is 0.8 μm]]> 16% The proportion was lower than that of the experimental group (20%). Silica powder <![CDATA[SiO2 purity: 98%, particle size: 0.4μm]]> 9% The proportion was higher than that of the experimental group (6%). aluminate cement Model CA-70 12% The proportion was higher than that of the experimental group (8%). Water reducing agent Traditional naphthalene-based water-reducing agents (non-polycarboxylate-based) 0.4% Replacement experimental group PCA®-300P Defoamer Methyl silicone oil (organosilicon) 0.2% Consistent with the experimental group Interface bonding enhancer - (Silicon nitride-free iron powder) 0% B. Finished Product Performance Testing: The finished products of this embodiment and the control group were tested separately. ① Interface bonding strength test; ② Thermal shock stability test (50 cycles of water cooling at 1100℃); ③ Overall structure porosity test; ④ Industrial trial life records; ⑤ Interface defect detection (using a metallographic microscope to observe the interface microstructure).

[0046] Stability of process parameters: In this example, the moisture content of the raw materials after drying was 0.3%, the slurry fluidity was 180 mm, and the density of each layer after vibration molding was ≥95%; in the control group, the slurry fluidity was 165 mm and the density was 90%. Interfacial bonding strength: The interfacial bonding strength of the finished product in this embodiment is 3.6-3.8 MPa, while that of the control group is only 2.1-2.3 MPa; Thermal shock stability: The finished product in this embodiment showed no cracks or peeling after 50 thermal shock cycles, while the control group showed interface cracks after 28 cycles. Structural porosity: In this embodiment, the average porosity of the finished product is 18%, and the porosity at the interface is ≤20%; the average porosity of the control group is 25%, and the porosity at the interface is 32%. Industrial trial: The product in this embodiment served for 18.5 months, while the product in the control group only served for 11 months; Microstructure: Metallographic microscopy showed that there were no obvious gaps at the gradient interfaces in this embodiment, and the components transitioned uniformly; while there were more gaps at the gradient interfaces in the control group, and the components were not connected continuously.

[0047] The key differences between the control group and the experimental group were verified as follows: Comparison Dimensions Control group (existing technology) experimental group number of structural layers 3 layers (no transition layer) 5 layers (including 2 transition layers) Interface bonding enhancer none Silicon nitride iron + titanate coupling agent Anti-erosion layer aggregate ordinary silicon carbide particles <![CDATA[Silicon nitride bonded silicon carbide particles (Si3N4 ≥ 20%)]]> Difference in thermal expansion coefficients between adjacent layers <![CDATA[≈1.8×10 -6 ℃]]> <![CDATA[0.3×1010 -6 ℃]]> Interface bonding strength ≈2.2MPa 3.6-3.8MPa Thermal shock stability Cracks appeared after 25 cycles of water cooling at 1100℃. 50 times without cracks Resistance to slag erosion rate ≈1.2mm / h 0.3mm / h

[0048] The preparation process in this embodiment precisely solves the technical problem of existing technologies where "the uniform curing process cannot be adapted to the characteristics of each layer of components, exacerbating interface defects and reducing the overall integrity of the gradient structure." Specific effects include: Adapted to the characteristics of each layer of components: The segmented curing process avoids the problems of "insufficient dehydration at low temperatures and rapid evaporation of moisture at high temperatures", reduces interfacial pores and microcracks, and improves structural density; Improving interfacial bonding quality: Through interfacial pretreatment and appropriate curing and calcination parameters, interlayer chemical reactions are promoted, component transitions are achieved smoothly, and interfacial bonding strength is significantly improved. The process has strong stability: the parameters of each step are clear and controllable, the finished product has good consistency in performance, and it is highly reproducible in industry; Extended service life: Improved overall product integrity and resistance to failure, with an industrial trial life 68% longer than products prepared using existing processes.

[0049] The fabrication process of blast furnace tapping area using functionally graded castable refractory: On the one hand, the segmented curing method is adapted to the preparation of the blast furnace tapping area. The room temperature curing stage ensures the initial solidification of each layer of slurry and avoids early deformation; the step-by-step temperature increase curing at 60℃ and 110℃ achieves slow evaporation of moisture and effectively prevents the rapid escape of moisture and the formation of pores; low-temperature calcination (600℃) removes residual organic matter and crystal water, and high-temperature calcination (1200℃) promotes the formation of ceramic bonding phase and adapts to the curing characteristics of different components; Secondly, it achieves interface pretreatment enhancement. The titanate coupling agent ethanol solution can clean the surface of the lower layer, form active functional groups, improve the wettability of the upper and lower slurries, promote molecular diffusion and chemical bonding, and reduce interfacial voids; The three vibration parameters were matched to ensure the quality of interlayer bonding. The vibration frequency and time were adjusted according to the characteristics of each layer of slurry (55Hz, 4min for the main layer and 50Hz, 3min for the transition layer) to ensure the compactness of the main layer while avoiding component stratification in the transition layer due to excessive vibration, thus further ensuring the quality of interlayer bonding.

Claims

1. A functional gradient castable for blast furnace tapping areas, characterized in that... It includes heat-insulating and wear-resistant castable, heat-insulating, wear-resistant and erosion-resistant interface transition material, erosion-resistant castable, erosion-resistant and high-temperature heat-insulating interface transition material, and high-temperature heat-insulating castable, which are arranged in a gradient from the outside to the inside. (1) The heat-insulating and wear-resistant castable is composed of the following components by mass percentage: 30-35% corundum sand, 20-25% silicon carbide sand, 15-20% alumina powder, 5-8% silica powder, 8-12% CA-70 aluminate cement, 1-2% silicon nitride iron powder, 0.2-0.5% PCA®-300P polycarboxylate powder water-reducing agent, and 0.1-0.3% organosilicon defoamer; (2) The heat-insulating, wear-resistant and corrosion-resistant interface transition material is composed of the following components by mass percentage: 25-30% corundum sand, 15-20% silicon carbide sand, 20-25% alumina powder, 8-12% silica powder, 6-10% CA-70 aluminate cement, 1.5-2.5% interface bonding reinforcing agent, 0.3-0.6% PCA®-300P polycarboxylate powder water-reducing agent, and 0.1-0.3% organosilicon defoamer; (3) The anti-erosion castable is composed of the following components by mass percentage: 35-40% fused alumina sand, 25-30% silicon nitride-bonded silicon carbide particles, 12-18% alumina powder, 4-6% silica powder, 5-8% CA-80 aluminate cement, 2-3% silicon nitride iron powder, 0.4-0.7% PCA®-400P polycarboxylate powdered water-reducing agent, and 0.1-0.3% organosilicon defoamer; (4) The anti-erosion and high-temperature insulation interface transition material is composed of the following components in the indicated mass percentages: 20-25% fused alumina sand, 15-20% silicon nitride bonded silicon carbide particles, 22-28% alumina micro powder, 6-10% silica micro powder, 4-7% CA-80 type aluminate cement, 1.5-2.5% interface bonding reinforcing agent, 0.3-0.6% PCA®-400P type polycarboxylate powdered water-reducing agent, and 0.1-0.3% organosilicon defoamer; (5) The high-temperature heat-insulating castable is composed of the following components by mass percentage: 30-35% lightweight corundum aggregate, 25-30% alumina hollow spheres, 18-22% alumina micro powder, 5-8% silica micro powder, 6-10% CA-70 type aluminate cement, 0.2-0.5% PCA®-300P type polycarboxylate powder water-reducing agent, and 0.1-0.3% organosilicon defoamer.

2. The functional gradient castable refractory for the blast furnace tapping area according to claim 1, characterized in that, In the heat-insulating and wear-resistant castable: the corundum sand has a particle size of 5-10 mm and an Al2O3 purity of ≥99%; the silicon carbide sand has a particle size of 3-5 mm and an SiC purity of ≥98%; the alumina micro powder has a particle size of ≤1 μm and an Al2O3 purity of ≥99%; the silicon micro powder has a particle size of ≤0.5 μm and an SiO2 purity of ≥98%; the interface bonding reinforcing agent is silicon nitride iron powder with a particle size of ≤500 nm; In the heat-insulating, wear-resistant, and corrosion-resistant interface transition material: the corundum sand has a particle size of 2-5 mm and an Al2O3 purity of ≥99%; the silicon carbide sand has a particle size of 1-3 mm and an SiC purity of ≥98%; the alumina micro powder has a particle size of ≤1 μm and an Al2O3 purity of ≥99%; the silicon micro powder has a particle size of ≤0.5 μm and an SiO2 purity of ≥98%; the interface bonding reinforcing agent is silicon nitride iron powder and titanate coupling agent, with a mass ratio of silicon nitride iron powder to titanate coupling agent of 1:1, and the average particle size of the interface bonding reinforcing agent is ≤500 nm; In the aforementioned anti-corrosion castable: the fused alumina sand has a particle size of 5-15 mm and an Al2O3 purity ≥99.5%; the silicon nitride-bonded silicon carbide particles have a particle size of 3-8 mm; the silicon nitride-bonded silicon carbide particles are Si3N4-bonded SiC, wherein the Si3N4 content is ≥20%; the alumina micro powder has a particle size ≤1 μm and an Al2O3 purity ≥99%; the silicon micro powder has a particle size ≤0.5 μm and an SiO2 purity ≥98%. In the aforementioned anti-corrosion and high-temperature insulation interface transition material: the fused alumina sand (AL2O3) has a purity ≥99.5% and a particle size of 2-5mm; the silicon nitride-bonded silicon carbide particles contain ≥20% Si3N4 and have a particle size of 1-3mm; the alumina micro powder (AL2O3) has a purity ≥99% and a particle size ≤1μm; the silicon micro powder (SiO2) has a purity ≥98% and a particle size ≤0.5μm; the interface bonding reinforcing agent is silicon nitride iron powder + titanate coupling agent, with a mass ratio of 1:1 and a particle size ≤500nm. In the high-temperature insulating castable: the lightweight corundum aggregate has an AL2O3 content ≥98%, a particle size of 5-12mm, and a bulk density ≤1.8g / cm³; the alumina hollow spheres have an AL2O3 purity ≥98% and a particle size of 2-5mm; the alumina micro powder has an AL2O3 purity ≥99% and a particle size ≤1μm; and the silicon micro powder has an SiO2 purity ≥98% and a particle size ≤0.5μm.

3. The functional gradient castable refractory for the blast furnace tapping area according to claim 1, characterized in that, The organosilicon defoamer is methyl silicone oil.

4. A functionally graded blast furnace tapping area, characterized in that, It is prepared from the functional gradient castable of the blast furnace tapping area as described in claim 1 or 2, and adopts a five-layer gradient structure, from the outside to the inside being a heat-insulating and wear-resistant layer, an interface transition layer I, an anti-erosion working layer, an interface transition layer II, and a high-temperature heat-insulating layer; wherein: The heat-insulating and wear-resistant layer is cast from the heat-insulating and wear-resistant castable, and has a thickness of 30-50mm. The interface transition layer I is cast from the heat-insulating, wear-resistant and erosion-resistant interface transition material, with a thickness of 15-35mm. The anti-erosion working layer is cast from the anti-erosion castable and has a thickness of 90-110mm. The interface transition layer II is cast from the anti-corrosion and high-temperature insulation interface transition material, with a thickness of 15-35mm. The high-temperature insulation layer is cast from the high-temperature insulation castable and has a thickness of 50-70mm.

5. A process for preparing a functionally graded blast furnace tapping area as described in claim 4, characterized in that, Includes the following steps: Step 1: Raw material pretreatment: Place the aggregates required for each gradient layer in an oven to dry. The aggregates include corundum sand, silicon carbide sand, fused corundum sand, silicon nitride-bonded silicon carbide particles, lightweight corundum aggregate, and alumina hollow spheres. Seal and store the interface bonding reinforcing agent, water reducing agent, and defoamer separately. Step 2: Preparation of each layer of slurry: According to the component ratio of each gradient layer, add the aggregate and matrix powder to a forced mixer and dry mix for 3-5 minutes. The matrix powder includes alumina micro powder, silica micro powder, and aluminate cement. Then add the interface bonding enhancer, water-reducing agent, and defoamer, and continue mixing for 2-3 minutes. Finally, add 6-8% of deionized water according to the total mass of each layer of materials, and mix for 5-8 minutes to obtain the casting slurry for each layer. Step 3: Layered casting: Using a mold, cast the layers in the following order: "high temperature insulation layer → interface transition layer II → anti-corrosion working layer → interface transition layer I → heat insulation and wear-resistant layer". After each layer is cast, vibrate to form the layer. The vibration frequency is 45-60Hz and the time is 2-5 minutes. Before casting adjacent gradient layers, apply a 5-8% concentration of titanate coupling agent ethanol solution to the surface of the lower layer and let it stand for 10-15 minutes. Step 4: Segmented curing and solidification: First, cure in an environment of 20-25℃ and relative humidity ≥80%; then place in a curing kiln, raise the temperature to 60℃ at 5℃ / h, and maintain the temperature for 12 hours, then raise the temperature again and maintain the temperature again; finally, fire in segments, first raise the temperature, then fire at a constant temperature, then raise the temperature again and fire at a constant temperature again, and then demold after naturally cooling to room temperature to obtain the finished product.

6. The preparation process according to claim 5, characterized in that, In step 3, the vibration parameters of the heat insulation and wear-resistant layer and the anti-corrosion working layer are 55 Hz frequency and 4 min time; the vibration parameters of the interface transition layer I and the interface transition layer II are 50 Hz frequency and 3 min time.

7. The preparation process according to claim 5, characterized in that, In step 4, the natural cooling rate is ≤10℃ / h.