A high-sealing, erosion-resistant tundish inlet with a gradient composite structure and its manufacturing method

Abstract

This invention discloses a high-sealing, erosion-resistant tundish top nozzle with a gradient composite structure and its manufacturing method. The top nozzle body is divided into a funnel-shaped bowl area, a cylindrical flow channel area, and a conical connecting area. The inner wall of the bowl area is inlaid with a zirconium-carbon first erosion-resistant layer, and the inner wall of the flow channel area is inlaid with a magnesium-aluminum spinel second erosion-resistant layer containing an in-situ reinforcing phase, forming a stepped overlap between the layers. The outer wall of the connecting area has an annular dovetail groove and is filled with a thermally expanding sealing gasket composed of expanded graphite, expanded polytetrafluoroethylene, and aluminum silicate fiber. During manufacturing, a separate mold and isostatic pressing integrated molding process are used. By controlling the material trapping environment and isostatic pressure, the dissimilar materials are made to penetrate and mesh at the non-linear interface. This invention achieves dynamic compensation sealing at high temperatures, solving problems such as interface peeling of dissimilar materials, air intake oxidation, flow deviation erosion, and nodule blockage under high pulling speeds, significantly improving the service life of the nozzle.

Description

Technical Field

[0001] This invention belongs to the technical field of tundish top nozzles, and specifically discloses a high-sealing and erosion-resistant tundish top nozzle with a gradient composite structure and its manufacturing method. Background Technology

[0002] The tundish top nozzle is a key functional component connecting the tundish to the sliding gate (or submersible gate) mechanism. It is installed in the bottom seat brick of the tundish and mainly serves to guide the molten steel and regulate the flow field. During continuous casting production, the top nozzle must withstand the scouring, chemical corrosion, and severe thermal shock of high-temperature molten steel for a long time. Its service performance directly affects the quality of the continuously cast billet and the production efficiency.

[0003] As continuous casting technology develops towards high casting speeds and multi-furnace continuous casting, the operating conditions of the inlet are becoming increasingly demanding, currently facing the following three major technical challenges: 1. Sealing failure and secondary oxidation issues: The connection between the upper inlet and the lower submersible inlet is a critical point for air leakage. If the seal is not tight, air can easily be drawn in under the negative pressure of the flowing molten steel, leading to secondary oxidation of the molten steel, the formation of non-metallic inclusions, and even steel spillage. Although existing patents such as CN114367656A (reference document 1) propose to strengthen the connection by using internal and external threads and sintering at high temperatures, under long-term high-temperature service conditions, the threaded structure is prone to stress relaxation due to the difference in the thermal expansion coefficients of the materials, resulting in a decrease in dynamic sealing performance.

[0004] 2. Non-uniform erosion and nodule blockage in key areas: The nozzle bowl is subjected to the heaviest erosion from direct impact of molten steel. Furthermore, the inner wall of the runner is highly susceptible to chemical corrosion during the casting of high-alloy steel or calcium-treated steel, leading to diameter expansion, or blockage due to inclusions such as Al2O3. Existing patents, such as CN213496468U (reference document 2), propose embedding a large-diameter zirconium core within the nozzle body to improve erosion resistance. However, a zirconium core made of a single material cannot simultaneously guarantee thermal shock stability and chemical corrosion resistance, and the simple physical embedding is prone to detachment or crack propagation under severe thermal shock.

[0005] 3. Limited flow field stability and inclusion removal: Traditionally, the flow channel of a sprue is a simple straight cylinder structure, with molten steel flowing down in a straight line. At high casting speeds, dead zones easily form within the flow channel, hindering the removal of inclusions from the molten steel. Although existing research attempts to prevent clogging by blowing argon, this often lacks systematic integration with the sprue structure, resulting in uneven argon bubble distribution and potentially causing fluctuations in the liquid surface.

[0006] In summary, existing technologies often only address one specific problem among sealing, erosion resistance, or anti-clogging, lacking a systematic solution that integrates graded functional materials, dynamic compensation sealing, and swirling flow field optimization. Therefore, there is an urgent need to develop a high-sealing, erosion-resistant tundish top nozzle with a graded composite structure to meet the stringent requirements of modern steel metallurgy for efficient, long-life, and high-cleanliness casting. Summary of the Invention

[0007] The purpose of this invention is to provide a highly sealed and erosion-resistant tundish top nozzle with a gradient composite structure, in order to solve the technical problems of poor sealing performance leading to air intake oxidation, severe erosion of the bowl and flow channel leading to control loss, and flow channel blockage under high casting speed and multi-furnace continuous casting conditions.

[0008] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a high-sealing and erosion-resistant tundish top nozzle with a gradient composite structure, comprising a top nozzle body, wherein the top nozzle body is divided into a bowl-shaped area, a flow channel area, and a connecting area along the axial direction from top to bottom; the bowl-shaped area is funnel-shaped with a larger top and a smaller bottom, and the inner wall of the bowl-shaped area is inlaid with a first erosion-resistant layer; the flow channel area is cylindrical, and the inner wall of the flow channel area is inlaid with a second erosion-resistant layer; the connecting area is located at the bottom of the top nozzle body and is used to cooperate with the bottom nozzle, the outer wall of the connecting area has a tapered structure that gradually narrows from top to bottom, and the outer wall of the connecting area is provided with an annular dovetail groove, the annular dovetail groove being filled with a thermal expansion sealing gasket made of a refractory material that can expand in volume at high temperatures.

[0009] Preferably, the upper end of the second anti-erosion layer extends to the junction of the bowl area and the flow channel area, and forms a stepped overlapping structure with the lower end of the first anti-erosion layer.

[0010] Preferably, the thermal expansion sealing gasket is made of aluminum silicate fiber and expanded graphite composite.

[0011] Preferably, the first erosion-resistant layer is a zirconium oxide-graphite composite material with a thickness of 10-20 mm, and the material of the inlet body is aluminum-carbon.

[0012] Preferably, the bulk density of the first erosion-resistant layer material is 3.4-3.6 g / cm³. 3 The apparent porosity is 15%-19%.

[0013] Preferably, the second erosion-resistant layer is a magnesium-aluminum spinel inlaid ring, the inner diameter of which is the same as the inner diameter of the inlet body, and the bulk density of the second erosion-resistant layer material is 2.9-3.1 g / cm³. 3 The apparent porosity is 8%-10%.

[0014] Preferably, a microporous air-permeable ring is embedded inside the main body of the inlet of the flow channel area, and the microporous air-permeable ring is located directly below the second anti-erosion layer or alternately arranged therewith.

[0015] Preferably, the apparent porosity of the microporous breathable ring material is 18%-28%, and the bulk density is 2.85-3.15 g / cm³. 3 The breathability is 8-15D.

[0016] Preferably, a swirling flow generating structure is provided below the bowl-shaped area and at the entrance of the flow channel area; the swirling flow generating structure includes an annular base and a plurality of spiral guide vanes evenly distributed on the inner wall of the annular base.

[0017] Preferably, the annular dovetail groove has two channels.

[0018] Preferably, the bowl-shaped region is funnel-shaped, wider at the top and narrower at the bottom. The first anti-erosion layer is a zirconia-graphite composite material with a thickness of 10-20 mm, and the matrix material in this region is alumina-carbon. Zirconia undergoes a phase transformation at high temperatures, inducing microcrack toughening, while graphite has low expansion and lubricity. The combination of these two materials gives the bowl-shaped region good thermal shock stability and resistance to molten steel erosion, preventing loss of controllable material due to bowl deformation.

[0019] Preferably, the first erosion-resistant layer material is zirconium carbide with a bulk density of 3.4~3.6 g / cm3 and an apparent porosity of 15~19%. When the bulk density is too low and the apparent porosity is too high, the erosion-resistant layer material has too low density, a loose structure, and poor resistance to molten steel erosion; when the bulk density is too high and the apparent porosity is too low, the erosion-resistant layer material has poor thermal shock stability.

[0020] The raw materials of the first erosion-resistant layer material include, by weight, 60%~70% of fused calcium oxide stabilized zirconium oxide-corundum eutectic, 10%~18% of fine graphite, 11%~15% of fused magnesia, 5%~9% of resin, and 0.8%~3.5% of added antioxidant.

[0021] Preferably, the antioxidant is one or more of aluminum powder and silicon powder.

[0022] The electrofused calcium oxide stabilized zirconium oxide-corundum eutectic aggregate contains ≥85% ZrO2, 4%~14% CaO, and 5%~10% Al2O3 by mass. As a high-melting-point (~2700℃) oxide, it is chemically stable. Under the erosion of molten steel, it can form a dense zirconium-rich layer, directly resisting the chemical dissolution of molten steel and slag. In addition, this electrofused eutectic aggregate has a finely interwoven internal structure, and its grain boundary strength is much higher than that of a single particle. When the matrix is ​​eroded by slag, the aggregate can still maintain its structural integrity, preventing slag lines from penetrating deeper, forming a dynamic corrosion balance of "dissolution-blocking-re-densification", thereby delaying structural spalling.

[0023] The fused magnesia contains ≥97.5% MgO by mass and acts as an auxiliary stabilizer to reduce the thermal expansion rate of the material and improve its high-temperature thermal shock resistance.

[0024] The calcium oxide and magnesium oxide stabilizers are incorporated into the zirconia lattice through solid solution, preserving the high-temperature stable tetragonal phase to room temperature. When subjected to thermal shock at the rim or stress at the crack tip, a surface phase transformation is induced (accompanied by 3%-5% volume expansion). This effect closes cracks, absorbs energy, and significantly improves resistance to thermal shock and crack propagation. Furthermore, calcium oxide not only stabilizes the structure but also reacts with alumina inclusions in the molten steel to form low-melting-point calcium aluminate, preventing nodule formation and blockage, thus possessing a "chemical anti-blocking" function.

[0025] The fine graphite has a C mass percentage of ≥96% and a particle size of no more than 50μm. Graphite has high thermal conductivity and low wettability. The weak interfaces it constructs in the matrix can guide crack deflection, dissipate fracture energy, and prevent large-scale spalling.

[0026] The resin is a thermosetting phenolic resin commonly used in refractory shaped products, used for room temperature molding and carbonization at high temperature to form a bonding network.

[0027] During firing or initial use, these antioxidants preferentially react with residual oxygen, consuming it and protecting graphite from oxidation. The molten metal also fills pores, delaying the entry of external oxygen.

[0028] Antioxidants and graphite work synergistically. During high-temperature carbon burial sintering, aluminum and silicon powders react with graphite and nitrogen to generate whisker-like or fibrous carbides and nitrides. This not only significantly improves the high-temperature fracture toughness of the material but also avoids excessive strength reduction caused by the addition of graphite.

[0029] The erosion-resistant layer and the multi-layered composite structure of the main body work together. The erosion-resistant layer is responsible for directly resisting the impact of molten steel; the main body layer has high thermal conductivity, which can quickly transfer heat away and reduce the thermal gradient on the surface of the bowl. The two are formed into a gapless transition layer through cold isostatic pressing, which solves the contradiction between "poor thermal shock resistance of high corrosion-resistant materials (zirconia)" and "poor impact resistance of high thermal shock resistant materials (aluminum)".

[0030] The thickness of the first anti-erosion layer is 10-20mm, and it is designed according to the erosion intensity of molten steel, the erosion mechanism and the material properties. If the thickness is too small, the protective effect will be insufficient; if the thickness is too large, it will affect heat conduction or occupy the flow channel space.

[0031] Preferably, the flow channel area is cylindrical, the second anti-scouring layer is a magnesium aluminum spinel embedded ring with an inner diameter consistent with the inner diameter of the upper water inlet mother body, and the upper end of the second anti-scouring layer and the lower end of the first anti-scouring layer form a stepped overlapping structure to prevent molten steel from penetrating into the mother body.

[0032] Preferably, the second erosion-resistant layer material is magnesium aluminum spinel with a bulk density of 2.9~3.1 g / cm³. 3 The apparent porosity is 8-10%. When the bulk density is too low and the apparent porosity is too high, the erosion-resistant layer material has too low density, loose structure, and poor resistance to molten steel erosion; when the bulk density is too high and the apparent porosity is too low, the erosion-resistant layer material has poor thermal shock stability.

[0033] The raw materials of the second erosion-resistant layer material include, by weight, 85%~93% magnesium aluminum spinel, 2.0%~6.0% solid resin, 5%~9% liquid resin, and 3%~15% additives.

[0034] Preferably, the additive is one or more of aluminum powder, silicon powder, silicon carbide, boron, or boride.

[0035] The magnesium-aluminum spinel contains 65%~70% Al2O3 by mass, and its particle size distribution forms a dense framework. It has a high melting point of 2135℃, a dense and stable structure, and can resist the penetration of low-melting-point slag phases. The magnesium-aluminum spinel has a large wetting angle (incompatibility) with Al2O3 inclusions in the molten steel, making it difficult for inclusions to adhere and deposit, thus alleviating the "nodule" blockage at the nozzle from the root cause.

[0036] The solid and liquid resins are used for room temperature molding and carbonization at high temperature to form a bonded network.

[0037] The aluminum powder in the additives primarily provides the active metal, reacting with Si, N2, or C to form silane or AlON; silicon powder forms a reinforcing phase and promotes sintering in a reducing atmosphere; silicon carbide has high hardness and good thermal conductivity, improving erosion and thermal shock resistance; boron / borides such as amorphous boron and B4C, even in trace amounts, can significantly improve oxidation resistance and high-temperature strength. The additives mainly strengthen the matrix by reacting to form non-oxide phases.

[0038] The second anti-erosion layer has a good transition with the working layer in terms of material. Utilizing the low coefficient of thermal expansion and excellent thermal shock resistance of magnesium aluminum spinel, it absorbs the severe temperature shock during pouring and ladle replacement, preventing material spalling. Compared with traditional chromium-containing materials, magnesium aluminum spinel is non-toxic and harmless, and can significantly extend its service life by forming a dense protective layer to resist the erosion of molten steel.

[0039] The non-oxide phase generated during the firing process (reducing atmosphere) of the raw material components of the second erosion layer is mainly distributed in the matrix between spinel particles. These in-situ generated high-strength, low-porosity non-oxide phases can significantly strengthen the weak areas of the matrix and achieve a leap in overall erosion resistance.

[0040] Preferably, the connection area is used to mate with an immersion nozzle, and the composite sealing structure includes an annular dovetail groove formed on the outer wall of the connection area, and a thermal expansion sealing gasket filled in the annular dovetail groove.

[0041] The thermal expansion sealing gasket is made of refractory fiber that can expand in volume at high temperatures. Specifically, it is composed of expanded graphite, expanded polytetrafluoroethylene and aluminum silicate fiber, which takes into account high temperature resistance, corrosion resistance and high strength.

[0042] The raw materials of the thermal expansion sealing gasket material include, by weight, 40%~60% expanded graphite, 30%~50% expanded polytetrafluoroethylene, 5%~15% aluminum silicate fiber, and 0.3%~1% additives.

[0043] Preferably, the additive is a silane coupling agent, an amine or phenolic antioxidant, used to ensure the interfacial bonding strength between the fiber and the matrix at high temperatures.

[0044] The expanded graphite provides excellent thermal conductivity, high-temperature resistant matrix, and compression resilience.

[0045] The expanded polytetrafluoroethylene (ePTFE) serves as a flexible binder phase, filling the spaces between graphite layers and providing excellent chemical inertness and a low coefficient of friction.

[0046] The aluminum silicate fibers serve as the skeleton material and are distributed in a short fiber form.

[0047] Expanded graphite alone is prone to "shedding powder" and is porous. The addition of expanded polytetrafluoroethylene can fill the micropores between graphite sheets, forming a dense "labyrinth" sealing structure, which significantly reduces the leakage rate of high-pressure gases (such as helium and nitrogen).

[0048] Aluminosilicate fibers form a stable three-dimensional network skeleton at high temperatures. When the gasket is subjected to high-pressure fluid impact, this network can firmly lock the graphite and polytetrafluoroethylene body, preventing material "extrusion" or "blowout" failure. It also has excellent high-temperature creep resistance, effectively offsetting the volume shrinkage caused by weight loss of expanded graphite under high-temperature oxidizing conditions, helping the gasket maintain stable sealing stress throughout the entire thermal cycle and reducing thermal torque decay.

[0049] Pure polytetrafluoroethylene (PTFE) softens easily above 260°C. By introducing expanded graphite and high-temperature resistant fibers, the upper limit of oxidation resistance can be broadened. This composite gasket can still maintain its structural integrity in an oxidizing atmosphere of 450°C to 550°C, far exceeding that of a single material.

[0050] Furthermore, to improve casting quality and prevent nodule formation, a microporous venting ring is embedded inside the runner section. This microporous venting ring is connected to an external gas source via an air inlet channel to allow argon gas to permeate into the inner wall of the molten steel channel. The microporous venting ring is located directly below or alternately with the second anti-erosion layer.

[0051] The air-permeable ring material has an apparent porosity of 18%~28% and a bulk density of 2.85~3.15 g / cm³. 3 The air permeability is 8~15D. Controlling the porosity ensures basic air permeability while avoiding a reduction in erosion resistance. Controlling the bulk density ensures air permeability through remaining micropores while maintaining sufficient interparticle bonding strength to resist erosion by molten steel. Controlling the air permeability ensures a stable gas flow rate, allowing inclusions in the molten steel to float and preventing them from adhering to the inner wall of the nozzle, while also preventing excessive gas pressure from causing molten steel to churn and resulting in surface fluctuations.

[0052] The raw materials of the breathable ring material include, by weight, 57%~75% white corundum, 10%~15% flake graphite, 5%~10% zircon mullite, 5%~10% fused silica, 1%~3% metallic silicon, 0.5%~1% boron carbide, 2%~4.5% aluminum hydroxide, and 8%~12% added phenolic resin.

[0053] The white fused alumina aggregate provides skeletal support, and the fine powder fills the gaps between particles, improving the density and sintering activity of the green body. It has a high melting point, high hardness, and good erosion resistance.

[0054] The flake graphite improves thermal shock resistance, prevents molten steel penetration, and also has a lubricating effect to facilitate demolding.

[0055] The zircon mullite utilizes the phase transformation of ZrO2 to toughen and improve thermal shock resistance and erosion resistance.

[0056] The fused silica has a low coefficient of thermal expansion and low thermal conductivity, which can relieve thermal stress and transform into cristobalite at high temperatures to increase strength.

[0057] The metallic silicon reacts with carbon at high temperature to form SiC whiskers, which enhance the matrix strength and prevent oxidation.

[0058] The boron carbide acts as an antioxidant, preferentially oxidizing and consuming oxygen, thus protecting graphite and carbon from oxidation.

[0059] The aluminum hydroxide acts as a pore-forming agent, undergoing high-temperature dehydration and decomposition to generate uniform micropores, while simultaneously generating active alumina to enhance sintering activity.

[0060] The phenolic resin serves as a temporary binder, providing strength through room temperature curing and carbonizing at high temperatures to form a carbon network bonded phase.

[0061] Furthermore, to optimize the molten steel flow field and promote the flotation of inclusions, a swirling flow generating structure is integrally formed or embedded below the bowl-shaped region and at the entrance of the flow channel region. The swirling flow generating structure includes multiple guide vanes evenly distributed circumferentially. The guide vanes are spirally protruding to generate a rotating tangential flow in the molten steel, and the material used is the same as that of the second anti-erosion layer.

[0062] This invention further proposes a method for manufacturing a high-sealing, erosion-resistant tundish top nozzle with a gradient composite structure, comprising the following steps: 1) Ingredients: Mix the raw materials according to the weight ratio in the ingredient list; 2) Mixing and granulation: The prepared raw materials are put into a granulator for mixing and granulation; 3) Material restraint: Place the prepared material in the material restraint room, ensuring that the temperature in the material restraint room is 20~25℃ and the humidity is less than 38%, and the material restraint time is 7~15 hours; 4) Molding: Add the prepared inlet body material, first flushing layer material, second flushing layer material, vent ring material, and sealing gasket material into the mold respectively, and mold them in an isostatic pressing equipment at a molding pressure of 120~150MPa. 5) Drying: Dry the formed water inlet in a drying kiln at 220~250℃ for 18~24 hours; 6) Firing: Place the water inlet into a firing kiln in a reducing atmosphere (or nitrogen, non-oxidizing atmosphere) and hold at 1150~1350℃ for 5~6 hours. 7) Flaw detection: Perform X-ray flaw detection on the water inlet; 8) Packaging: Packaging is done after the finished product has passed inspection.

[0063] The present invention provides a high-sealing, erosion-resistant tundish top nozzle with a gradient composite structure, which has the following advantages: 1. The first erosion-resistant layer embedded in the inner wall of the bowl area is a zirconia-graphite composite material. Utilizing the high-temperature toughening mechanism of zirconia (inhibiting crack propagation) combined with the low expansion and lubricity of graphite, the bowl area possesses excellent thermal shock stability and resistance to molten steel erosion. It can effectively resist molten steel erosion and chemical corrosion, preventing controlled flow caused by bowl deformation. 2. The second erosion-resistant layer embedded in the inner wall of the flow channel area is a magnesium aluminum spinel embedded ring. Spinel material has excellent resistance to penetration and corrosion of inclusions in molten steel (especially calcium-treated steel). Compared with traditional materials, it can significantly delay abnormal damage to the flow channel caused by erosion or diameter expansion, maintain the stable flow state of molten steel in the flow channel, and avoid accidents caused by excessive local erosion. 3. The microporous venting ring embedded inside the main body of the flow channel area forms an air curtain barrier at the interface between the inner wall of the flow channel and the molten steel by introducing inert gas (such as argon) into the venting ring. This not only prevents steel slag penetration and adhesion, reducing blockage, but also promotes the flotation and removal of inclusions in the molten steel; simultaneously, the gas cooling effect reduces thermal shock to the parent material, preventing it from cracking due to rapid heating and cooling. 4. An integrally formed or embedded vortex generating structure at the entrance of the flow channel forces the molten steel to generate rotating turbulence after entering the flow channel. On the one hand, centrifugal force is used to concentrate inclusions towards the center, preventing them from accumulating on the wall and causing erosion; on the other hand, by changing the flow field mode, the shear layer commonly found in traditional straight-through flow channels is broken, significantly reducing the scouring effect of the molten steel on the bowl and flow channel junction, resulting in a more balanced service life. 5. The annular dovetail groove composite sealing structure on the outer wall of the connecting area, and the thermal expansion sealing gasket filled in the annular dovetail groove, have excellent high-temperature creep resistance and can significantly improve gas permeability resistance. Attached Figure Description

[0064] To more clearly illustrate the technical solutions of the embodiments disclosed in this invention, the accompanying drawings of the embodiments will be briefly described below. These drawings are for illustrative purposes only and are not intended to limit the scope of protection of this invention.

[0065] Figure 1 This is a half-section diagram of the top nozzle of a high-sealing, erosion-resistant tundish with a gradient composite structure according to the present invention.

[0066] Explanation of reference numerals in the attached drawings: 1-Inlet body; 2-First anti-erosion layer (zirconia anti-erosion layer); 3-Second anti-erosion layer (magnesium aluminum spinel anti-erosion layer); 4-Annular dovetail groove; 5-Thermal expansion sealing gasket; 6-Microporous venting ring; 7-Stainless steel metal pipe (air inlet channel); 8-Swirl generation structure; 81-Annular base; 82-Spiral guide vane. Detailed Implementation

[0067] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0068] Example 1 like Figure 1 As shown, this embodiment provides a high-sealing, erosion-resistant tundish inlet with a gradient composite structure, mainly comprising an inlet body 1 made of aluminum-carbon material, with an axially penetrating steel molten steel channel inside the inlet body 1. The inlet body 1 is divided axially from top to bottom into a bowl-shaped area, a flow channel area, and a connecting area.

[0069] In the bowl-shaped area: The region is funnel-shaped, wider at the top and narrower at the bottom. A first erosion-resistant layer 2 is embedded in the inner wall of the main body 1. The first erosion-resistant layer 2 is made of zirconium carbonaceous material (zirconia-graphite composite material) and has a thickness of 15 mm. In this embodiment, the bulk density of this layer is controlled at 3.4-3.6 g / cm³. 3 The apparent porosity is 15-19%. Zirconia undergoes a phase transformation at high temperatures, inducing microcrack toughening. Combined with the low expansion of graphite, this gives the bowl-shaped region excellent thermal shock resistance, effectively resisting the thermal shock during initial pouring of molten steel and long-term erosion. The raw materials of the first anti-erosion layer material, by weight, include: 60%~70% fused calcium oxide stabilized zirconia-corundum eutectic, 10%~18% micrographite, 11%~15% fused magnesia, 5%~9% resin, and 0.8%~3.5% added antioxidant. The antioxidant is one or more of metallic aluminum powder and metallic silicon powder.

[0070] In the flow channel region: The area is cylindrical. A second anti-erosion layer 3, made of magnesium aluminum spinel, is embedded in the inner wall of the main body 1. This material exhibits exceptional resistance to erosion and permeation by inclusions in the molten steel (especially calcium-treated steel). The inner diameter of the second anti-erosion layer 3 is the same as the inner diameter of the main body 1 at the inlet, and its bulk density is 2.9-3.1 g / cm³. 3 The apparent porosity is 8-10%. The erosion-resistant layer material is magnesium aluminum spinel with a bulk density of 2.9-3.1 g / cm³ and an apparent porosity of 8-10%. The raw materials of the second erosion-resistant layer material, by weight composition, include: 85%-93% magnesium aluminum spinel, 2.0%-6.0% solid resin, 5%-9% liquid resin, and 3%-15% additives. The additives are one or more of metallic aluminum powder, metallic silicon powder, silicon carbide, boron, or borides.

[0071] Specifically, the upper end of the second erosion-resistant layer 3 extends to the junction of the bowl-shaped area and the flow channel area, and forms a stepped overlap structure with the lower end of the first erosion-resistant layer 2 (e.g., Figure 1 As shown in the diagram, this structure, through the tortuous physical path, effectively blocks the penetration of high-temperature molten steel into the aluminum-carbon upper nozzle body 1, protecting the structural safety of the body. The raw materials of the thermal expansion sealing gasket material, by weight, include: 40%~60% expanded graphite, 30%~50% expanded polytetrafluoroethylene, 5%~15% aluminum silicate fiber, and 0.3~1% additives. The additives are silane coupling agents, amines, or phenolic antioxidants, used to ensure the interfacial bonding strength between the fiber and the matrix at high temperatures.

[0072] In the connection area: The connecting area is located at the bottom of the main body 1, and its outer wall has a tapered structure that gradually tapers from top to bottom, for insertion and mating with the submersible nozzle below. Two annular dovetail grooves 4 are formed on the outer wall of the connecting area, filled with thermal expansion sealing gaskets 5. The thermal expansion sealing gaskets 5 are made of a composite of aluminum silicate fiber and expanded graphite. During the casting process, as the heat of the steel flow is conducted, the sealing gaskets 5 undergo irreversible volume expansion due to heat. Under the limiting effect of the dovetail grooves 4, they generate outward radial pressure, tightly fitting against the inner wall of the lower nozzle, forming a dynamic compensation seal, fundamentally solving the problem of air intake and oxidation.

[0073] Example 2 This embodiment is an optimization of the functions based on embodiment 1. For example... Figure 1 As shown, a microporous air-permeable ring 6 is embedded inside the main body of the inlet body 1, in the flow channel area.

[0074] The microporous breathable ring 6 is made of corundum material with high porosity, with an apparent porosity of 18%-28% and a bulk density of 2.85-3.15 g / cm³. 3 The air permeability is controlled between 8-15D. The microporous air-permeable ring 6 is connected to an external argon gas source through a stainless steel metal tube 7 embedded in the body.

[0075] During casting, a trace amount of argon gas permeates through the pores of the microporous venting ring 6 into the inner wall of the flow channel, forming a continuous gas curtain barrier. This gas curtain can not only prevent inclusions such as Al2O3 from adhering to the inner wall and reduce nodule blockage, but also buffer the thermal shock of high temperature to the aluminum-carbon matrix through the cooling effect of the gas, thus extending the service life of the nozzle.

[0076] Example 3 This embodiment further optimizes the flow field. A vortex generating structure 8 is set at the junction of the bowl-shaped region and the inlet of the flow channel region (i.e., the region where the molten steel flow velocity is the highest and the flow direction changes abruptly).

[0077] The swirl generating structure 8 includes an annular base 81 fixed within the flow channel, and four spiral guide vanes 82 evenly distributed on the inner wall of the annular base 81. The guide vanes 82 protrude in a spiral shape and extend towards the center of the flow channel.

[0078] As molten steel flows through this area, under the forced guidance of the spiral guide vanes 82, the steel flow changes from linear motion to a rotating tangential flow. The resulting centrifugal force causes light inclusions in the molten steel to converge towards the center of the flow channel and promotes their flotation and removal. At the same time, the rotating flow breaks the biased scouring pattern of the traditional straight-through flow channel, making the impact of the molten steel on the junction of the bowl and the flow channel more uniform and avoiding premature failure caused by excessive local erosion.

[0079] Example 4 A method for manufacturing a high-sealing, erosion-resistant tundish top nozzle with a gradient composite structure includes the following steps: 1) Ingredients: Mix the raw materials according to the weight ratio in the ingredient list; 2) Mixing and granulation: The prepared raw materials are put into a granulator for mixing and granulation; 3) Material restraint: Place the prepared material in the material restraint room, ensuring that the temperature in the material restraint room is 20~25℃ and the humidity is less than 38%, and the material restraint time is 7~15 hours; 4) Molding: Add the prepared inlet body material, first flushing layer material, second flushing layer material, vent ring material, and sealing gasket material into the mold respectively, and mold them in an isostatic pressing equipment at a molding pressure of 120~150MPa. 5) Drying: Dry the formed water inlet in a drying kiln at 220~250℃ for 18~24 hours; 6) Firing: Place the water inlet into a firing kiln in a reducing atmosphere (or nitrogen, non-oxidizing atmosphere) and hold at 1150~1350℃ for 5~6 hours. 7) Flaw detection: Perform X-ray flaw detection on the water inlet; 8) Packaging: Packaging is done after the finished product has passed inspection.

[0080] Example 5 This embodiment is an optimization of Embodiment 1. A microporous venting ring 6 is embedded within the upper inlet body 1 of the flow channel area, below the second anti-erosion layer 3. The microporous venting ring 6 is made of corundum material with high porosity and is connected to an argon gas source via a stainless steel metal pipe 7 embedded within the upper inlet body 1. During casting, a trace amount of argon gas permeates through the pores of the microporous venting ring 6 to the inner wall of the molten steel channel, forming a gas film that effectively blocks the adhesion of Al2O3 inclusions.

[0081] In this example, the first erosion-resistant layer material is zirconium carbide, with a bulk density of 3.4~3.6 g / cm³. 3 The apparent porosity is 15-19%.

[0082] The raw materials of the first erosion-resistant layer material include, by weight, 60%~70% of fused calcium oxide stabilized zirconium oxide-corundum eutectic, 10%~18% of fine graphite, 11%~15% of fused magnesia, 5%~9% of resin, and 0.8%~3.5% of added antioxidant.

[0083] The antioxidant is one or more of aluminum powder and silicon powder.

[0084] In this example, the second erosion-resistant layer material is magnesium aluminum spinel with a bulk density of 2.9~3.1 g / cm³. 3 The apparent porosity is 8-10%.

[0085] The raw materials of the second erosion-resistant layer material include, by weight, 85%~93% magnesium aluminum spinel, 2.0%~6.0% solid resin, 5%~9% liquid resin, and 3%~15% additives.

[0086] Preferably, the additive is one or more of aluminum powder, silicon powder, silicon carbide, boron, or boride.

[0087] The raw materials of the thermal expansion sealing gasket material shown in this example contain, by weight, 40%~60% expanded graphite, 30%~50% expanded polytetrafluoroethylene, 5%~15% aluminum silicate fiber, and 0.3~1% additives.

[0088] The additives are silane coupling agents, amines, or phenolic antioxidants, used to ensure the interfacial bonding strength between the fiber and the matrix at high temperatures.

[0089] The air-permeable ring material shown in this example has an apparent porosity of 18%~28% and a bulk density of 2.85~3.15 g / cm³. 3 Breathability 8~15D.

[0090] The raw materials of the breathable ring material include, by weight, 57%~75% white corundum, 10%~15% flake graphite, 5%~10% zircon mullite, 5%~10% fused silica, 1%~3% metallic silicon, 0.5%~1% boron carbide, 2%~4.5% aluminum hydroxide, and 8%~12% added phenolic resin.

[0091] A method for manufacturing a high-sealing, erosion-resistant tundish top nozzle with a gradient composite structure includes the following steps: 1) Ingredients: Mix the raw materials according to the weight ratio in the ingredient list; 2) Mixing and granulation: The prepared raw materials are put into a granulator for mixing and granulation; 3) Material restraint: Place the prepared material in the material restraint room, ensuring that the temperature in the material restraint room is 20~25℃ and the humidity is less than 38%, and the material restraint time is 7~15 hours; 4) Molding: Add the prepared inlet body material, first flushing layer material, second flushing layer material, vent ring material, and sealing gasket material into the mold respectively, and mold them in an isostatic pressing equipment at a molding pressure of 120~150MPa. 5) Drying: Dry the formed water inlet in a drying kiln at 220~250℃ for 18~24 hours; 6) Firing: Place the water inlet into a firing kiln in a reducing atmosphere (or nitrogen, non-oxidizing atmosphere) and hold at 1150~1350℃ for 5~6 hours. 7) Flaw detection: Perform X-ray flaw detection on the water inlet; 8) Packaging: Packaging is done after the finished product has passed inspection.

[0092] Example 6 This embodiment is an improvement upon Embodiment 1. A swirling flow generating structure 8 is installed at the junction of the bowl-shaped region and the flow channel region, i.e., the area where the molten steel flow velocity is highest and the flow direction changes. The swirling flow generating structure 8 includes an annular base 81 and four spiral guide vanes 82 evenly distributed on its inner wall. The guide vanes 82 have the same spiral direction. When the molten steel flows through, it is forcibly guided by the guide vanes 82, forming a swirling flow. This swirling flow helps reduce dead zones in the tundish and increases the near-wall flow velocity in the nozzle, improving static pressure, thereby suppressing turbulence and reducing the risk of slag entrapment.

[0093] In this example, the first erosion-resistant layer material is zirconium carbide, with a bulk density of 3.4~3.6 g / cm³. 3 The apparent porosity is 15-19%.

[0094] The raw materials of the first erosion-resistant layer material include, by weight, 60%~70% of fused calcium oxide stabilized zirconium oxide-corundum eutectic, 10%~18% of fine graphite, 11%~15% of fused magnesia, 5%~9% of resin, and 0.8%~3.5% of added antioxidant.

[0095] The antioxidant is one or more of aluminum powder and silicon powder.

[0096] In this example, the second erosion-resistant layer material is magnesium aluminum spinel with a bulk density of 2.9~3.1 g / cm³. 3 The apparent porosity is 8-10%.

[0097] The raw materials of the second erosion-resistant layer material include, by weight, 85%~93% magnesium aluminum spinel, 2.0%~6.0% solid resin, 5%~9% liquid resin, and 3%~15% additives.

[0098] Preferably, the additive is one or more of aluminum powder, silicon powder, silicon carbide, boron, or boride.

[0099] The raw materials of the thermal expansion sealing gasket material shown in this example contain, by weight, 40%~60% expanded graphite, 30%~50% expanded polytetrafluoroethylene, 5%~15% aluminum silicate fiber, and 0.3~1% additives.

[0100] The additives are silane coupling agents, amines, or phenolic antioxidants, used to ensure the interfacial bonding strength between the fiber and the matrix at high temperatures.

[0101] The swirl generation structure shown in this example uses the same material as the second erosion-resistant layer.

[0102] A method for manufacturing a high-sealing, erosion-resistant tundish top nozzle with a gradient composite structure includes the following steps: 1) Ingredients: Mix the raw materials according to the weight ratio in the ingredient list; 2) Mixing and granulation: The prepared raw materials are put into a granulator for mixing and granulation; 3) Material restraint: Place the prepared material in the material restraint room, ensuring that the temperature in the material restraint room is 20~25℃ and the humidity is less than 38%, and the material restraint time is 7~15 hours; 4) Molding: Add the prepared inlet body material, first flushing layer material, second flushing layer material, vent ring material, and sealing gasket material into the mold respectively, and mold them in an isostatic pressing equipment at a molding pressure of 120~150MPa. 5) Drying: Dry the formed water inlet in a drying kiln at 220~250℃ for 18~24 hours; 6) Firing: Place the water inlet into a firing kiln in a reducing atmosphere (or nitrogen, non-oxidizing atmosphere) and hold at 1150~1350℃ for 5~6 hours. 7) Flaw detection: Perform X-ray flaw detection on the water inlet; 8) Packaging: Packaging is done after the finished product has passed inspection.

[0103] Table 1 lists the raw material addition amounts for each embodiment and comparative example of the microporous breathable ring material of the present invention.

[0104] Table 2 is a list of the raw material addition amounts for each embodiment and comparative example of the first erosion-resistant layer of the present invention.

[0105] Table 3 is a list of the raw material addition amounts for each embodiment and comparative example of the second erosion-resistant layer of the present invention.

[0106] Table 4 shows the main process parameters of each embodiment and comparative example of the present invention.

[0107] Table 5 lists the performance test results of various embodiments and comparative examples of the microporous breathable ring material of the present invention.

[0108] Table 6 is a list of performance test results for each embodiment and comparative example of the first erosion-resistant layer of the present invention.

[0109] Table 7 is a list of performance test results for various embodiments and comparative examples of the second erosion-resistant layer of the present invention.

[0110] Table 1 (Wt, %) Table 2 (Wt, %) Table 3 (Wt, %) Table 4 Table 5 Table 6 Table 7 As shown in Examples 1-3 of Tables 1, 2, and 3, within the raw material addition amounts specified in this invention, the breathable ring material contains appropriate amounts of white corundum, flake graphite, zircon mullite, fused silica, metallic silicon, boron carbide, aluminum hydroxide, and phenolic resin; the sealing gasket material contains appropriate amounts of expanded graphite, expanded polytetrafluoroethylene, aluminum silicate fiber, and additives; the first erosion-resistant layer material contains appropriate amounts of fused calcium oxide stabilized zirconium oxide-corundum eutectic material, fine graphite, fused magnesia, resin, and antioxidants; and the second erosion-resistant layer material contains appropriate amounts of magnesium aluminum... By combining spinel, solid resin, liquid resin, and additives, and by controlling process parameters such as the material temperature, material time, molding pressure, firing temperature, and holding time, a tundish top nozzle with excellent high-temperature creep resistance and good sealing performance can be prepared. This nozzle also has excellent resistance to steel slag penetration and erosion, prevents adhesion and reduces blockage of the flow channel and bowl area, and can promote the removal of inclusions in the molten steel by changing the steel flow field. This significantly reduces the scouring effect of the molten steel on the bowl and flow channel junction, resulting in a more balanced service life.

[0111] In contrast, in Comparative Examples 1 and 2 where the amount of raw materials added and the production process were not controlled, the water inlet was prone to poor sealing, which led to the intake of air and the generation of oxide inclusions. The bowl area and flow channel area had poor erosion resistance and poor corrosion resistance, and were prone to the adhesion of inclusions or uneven flow, resulting in uneven damage and a short service life, which could not meet the performance requirements of the product.

[0112] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-sealing scouring-resistant tundish nozzle with a gradient composite structure, comprising a nozzle body (1), characterized in that: The upper water inlet body (1) forms a steel liquid channel through the axial direction. The upper water inlet body (1) is divided into a bowl-shaped area, a flow channel area and a connecting area from top to bottom along the axial direction. The bowl-shaped area is funnel-shaped with a larger upper part and a smaller lower part. The inner wall of the bowl-shaped area is inlaid with a first anti-erosion layer (2). The flow channel area is cylindrical. The inner wall of the flow channel area is inlaid with a second anti-erosion layer (3). The connecting area is located at the bottom of the upper water inlet body (1) and is used to cooperate with the lower water inlet. The outer wall of the connecting area is a cone-shaped structure that gradually narrows from top to bottom. The outer wall of the connecting area is provided with an annular dovetail groove (4). The annular dovetail groove (4) is filled with a thermal expansion sealing gasket (5) made of refractory material that can expand in volume at high temperature.

2. The high-sealing, scour-resistant tundish lip, according to claim 1, characterized by, The raw materials of the first erosion-resistant layer (2) include, by weight percentage: fused calcium oxide stabilized zirconium oxide-corundum eutectic material: 60%~70%; fine graphite: 10%~18%; fused magnesia: 11%~15%; resin: 5%~9%; added antioxidant: 0.8%~3.5%; wherein, the ZrO2 mass percentage of the fused calcium oxide stabilized zirconium oxide-corundum eutectic material is ≥85%, and the CaO mass percentage is 4%~14%.

3. The high-sealing, erosion-resistant tundish inlet according to claim 1, characterized in that, The raw materials of the second erosion-resistant layer (3) include, by weight percentage: magnesium aluminum spinel: 85%~93%; solid resin: 2.0%~6.0%; liquid resin: 5%~9%; and additives: 3%~15%. The additives are one or more of aluminum powder, silicon powder, silicon carbide, boron or boride.

4. The high sealed turbulence pad shroud according to claim 1, wherein The raw materials of the thermal expansion sealing gasket (5) include, by weight percentage: expanded graphite: 40%~60%; expanded polytetrafluoroethylene: 30%~50%; aluminum silicate fiber: 5%~15%; and additives: 0.3%~1%.

5. The high sealed turbulence pad shroud according to claim 1, wherein: The main body (1) of the upper water inlet of the flow channel is provided with a microporous air-permeable ring (6). The raw materials of the microporous air-permeable ring (6) include, by weight percentage: white corundum 57%~75%, flake graphite 10%~15%, zircon mullite 5%~10%, fused silica 5%~10%, metallic silicon 1%~3%, boron carbide 0.5%~1%, aluminum hydroxide 2%~4.5%, and added phenolic resin 8%~12%. A vortex generating structure (8) is provided below the bowl area and at the entrance of the flow channel area. The material of the vortex generating structure (8) is the same as that of the second anti-erosion layer (3).

6. The high sealed turbulence resistant tundish lip of claim 1, wherein: The bulk density of the first erosion-resistant layer (2) is 3.4-3.6 g / cm³. 3 The apparent porosity is 15-19%; the bulk density of the second erosion-resistant layer (3) is 2.9-3.1 g / cm³. 3 The apparent porosity is 8-10%; the apparent porosity of the microporous breathable ring (6) is 18%-28%, and the air permeability is 8-15D.

7. A method of manufacturing a high sealing scouring resistant tundish nozzle according to any one of claims 1 to 6, characterized in that, Includes the following steps: S1, Mix the raw materials according to the ingredient list of each layer; S2, put the prepared raw materials into the granulator for granulation; S3, Place the prepared material into the material holding room, control the workshop temperature at 20-25℃, humidity <38%, and the material holding time is 7-15 hours; S4, the upper water inlet body material, the first flushing layer material, the second flushing layer material, the vent ring material, and the sealing gasket material are added into the mold respectively, and formed using an isostatic pressing equipment with a forming pressure of 120-150MPa. S5, dry the formed sprue at 220-250℃ for 1824h; S6. Place the dried nozzle into a firing kiln in a reducing atmosphere, nitrogen atmosphere or non-oxidizing atmosphere, and keep it at 1150-1350℃ for 5-6 hours. S7, to inspect and package the sprue after firing.

8. The manufacturing method according to claim 7, characterized in that: In step 4), the first scouring layer material, the second scouring layer material, and the upper water inlet body material are formed into a gapless gradient transition layer by isostatic pressing.

9. The manufacturing method of claim 7, wherein: Step 6) During the firing process, a non-oxide reinforced phase is generated in situ in the matrix of the second erosion layer (3).

10. The manufacturing method of claim 7, wherein: The forming process in S4 is as follows: using a separate mold according to a preset geometric configuration, the first flushing layer material, the second flushing layer material, and the upper gate body material are respectively filled into the corresponding areas of the mold, so that the loading surfaces of different materials come into contact with each other and form a non-linear interface; during the isostatic pressing process, the compression ratio difference between different materials is used to make the heterogeneous materials interpenetrate and mechanically mesh at the interface, thereby obtaining a dense green body with continuous gradient transition characteristics before firing.

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