Submersed nozzle as well as preparation method and application thereof

Abstract

The invention discloses a submersed nozzle which sequentially comprises an outer layer, a body, a base body and a coating layer from outside to inside. The matrix is prepared by mixing and sintering the following components in percentage by mass: 5-10% of magnesia, 5-10% of corundum, 70-80% of a magnesium-iron spinel solid solution, 5-10% of a sintering aid, 1-5% of a carbon source and 1-5% of an additional binding agent; the coating layer is formed by mixing and sintering the following components in percentage by mass: 80-90% of iron-based powder and 10-20% of additive; a liquid protection film is formed in the molten steel continuous casting process, SiO and CO generated in the nozzle body in a reaction mode are restrained from diffusing into molten steel, Al in molten steel is restrained from reacting with the SiO and the CO to generate Al2O3 inclusions, the good anti-blocking effect is achieved, the service life is long, and the anti-blocking nozzle not only can be applied to continuous casting submersed nozzles, but also can be applied to continuous casting of the submersed nozzles. And meanwhile, the method can also be applied to the high-temperature-resistant industry fields such as blockage prevention of steel ladle long nozzles adopting aluminum deoxidized steel and anti-nodulation of tundish stopper rods, and the problem that submersed nozzles are prone to nodulation and blockage in the pouring process of aluminum deoxidized steel such as automobile sheets at present is solved.

Description

Technical Field

[0001] This invention belongs to the field of steelmaking continuous casting technology, specifically relating to a submerged entry nozzle, its preparation method, and its application. Background Technology

[0002] Submerged entry nozzles are one of the "three major components" in continuous casting and are crucial functional materials. During use, they are positioned between the tundish and the crystallizer. Aluminum-carbon nozzles have poor resistance to mold flux erosion and thermal shock. Furthermore, their poor thermal conductivity leads to slag buildup and alumina inclusions, causing nozzle blockage and severely impacting continuous casting. In aluminum-carbon-zirconium composite nozzles, CaO-stabilized zirconium dioxide undergoes calcium oxide desolvation, causing instability and fragmentation of the stabilized zirconium oxide, further exacerbating erosion at the slag line. Additionally, in the production of ultra-low carbon automotive steel, aluminum-carbon and aluminum-carbon-zirconium composite nozzles commonly exhibit nozzle nodule formation. Improving this phenomenon requires material modification.

[0003] In the published literature, Japanese Patent (Japanese Patent Application Publication No. 4-224061) and Chinese Patent (CN1062248C) proposed a CaO-ZrO2-C lining material and a material to prevent alumina blockage. Both patents utilize the fact that alumina can easily react with CaO or calcium fluoride in the lining material to form a low-melting-point phase, thereby reducing alumina deposition. However, in actual use, the anti-blocking effect is not good as the casting time increases.

[0004] The principle of alumina accumulation in submerged nozzles is twofold. First, when aluminum-killed molten steel is continuously cast, the aluminum added to the molten steel as a deoxidizer reacts with the refractory material constituting the submerged nozzle, resulting in non-metallic inclusions such as alumina (FR2642687A1). This process begins with the reaction of SiO2 (solid) and C (solid) in the nozzle material to generate SiO (gas) and CO (gas). Then, SiO (gas) and CO (gas) diffuse into the molten steel and react with Al in the molten steel to generate Al2O3 (solid), Si, and C. Second, nozzle blockage is related to the wetting and freezing of the molten steel and the precipitation of alumina on the surface of the relatively cold refractory material. After alumina inclusions are generated, they continuously deposit and grow on the inner wall of the nozzle (CA2260197A1).

[0005] Therefore, researching and developing new anti-clogging materials for submerged entry nozzles to reduce clogging in continuous casting is of great significance for improving continuous casting production efficiency. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides an immersion nozzle that forms a liquid protective film during the continuous casting process of molten steel, inhibiting the diffusion of SiO (gas) and CO (gas) generated in the nozzle body into the molten steel. This fundamentally suppresses the reaction of Al in the molten steel with the immersion nozzle to produce Al2O3 inclusions. It has excellent anti-clogging effect and long service life. It can be applied not only to continuous casting immersion nozzles, but also to anti-clogging of long nozzles in ladles using aluminum deoxidized steel and anti-nodulation of tundish stoppers in high-temperature industries. It overcomes the problem of nodulation and clogging of immersion nozzles in the casting process of aluminum deoxidized steel, such as automotive steel sheets, and is expected to be widely used in large-scale production.

[0007] To achieve the above objectives, the following technical solution is adopted: An immersion gate, comprising, from the outside in, an outer layer, a body, a substrate, and a coating layer; The matrix, by mass percentage, consists of: 5-10% magnesia, 5-10% corundum, 70-80% solid solution of magnesium-iron spinel, 5-10% sintering aid, 1-5% carbon, and 1-5 wt% binder, which are mixed and sintered together. The coating layer is formed by sintering 80-90% iron-based powder and 10-20% additives by mass percentage.

[0008] According to the above scheme, the solid solution of the magnesium-iron spinel is represented as Mg x Fe y Al 2-x-y O4(x+y≦2), the solid solution includes the following forms: MgFe2O4, MgAl2O4, Mg(Fe,Al)2O4, FeAl2O4.

[0009] According to the above scheme, the solid solution particle size composition of the magnesia, corundum, and magnesium-iron spinel is as follows: 3-1mm 20-30%, 1-0.5mm 30-40%, 0.5-0.088mm 20-35%, and less than 0.088mm 10-15%.

[0010] According to the above scheme, the sintering aid is one or a combination of several of andalusite, kyanite, sillimanite, cordierite, zircon, wollastonite, and kaolin; the particle size is as follows: 1-0.5mm 35-65%, 0.5-0.088mm 35-65%.

[0011] According to the above scheme, the carbon source is graphite, including natural graphite or artificial graphite.

[0012] According to the above scheme, the binder is one or a combination of several of phenolic resin, furan resin and polyvinyl alcohol.

[0013] According to the above scheme, the iron-based powder is one or a combination of FeO powder, Fe2O3 powder, and Fe2O3·FeO powder; the additive is one or a combination of quartz, mullite, zirconium oxide, or magnesium aluminum spinel. The coating slurry is dispersed using an organic solvent, which can be selected from polyvinyl alcohol or polystyrene, and the mixed slurry ensures that the solid phase component content is 50-70%.

[0014] According to the above scheme, the outer layer is made of refractory fiber; specifically, it is aluminum silicate fiber or alumina fiber.

[0015] According to the above scheme, the body is made of aluminum carbon, zirconium carbon, or aluminum zirconium carbon.

[0016] The present invention also provides a method for preparing the above-mentioned submersible nozzle, comprising the following steps: (1) Select the raw materials of the matrix according to the design composition and particle size distribution and mix them to obtain the matrix mixture; (2) The material is laid out in the manner of first arranging the main body and then arranging the base mixture, and isostatic pressing is used for molding; (3) The raw materials for the coating layer are dispersed in an organic solvent to obtain a coating slurry, which is then coated on the inside of the sprue substrate; (4) Under a protective atmosphere, heat to 1450~1550℃ and sinter for 2-6 hours; (5) The prefabricated refractory fiber is bound to the outside of the nozzle body with a high-temperature adhesive.

[0017] According to the above scheme, in step (1), a planetary ball mill is used for mixing. The mixing is carried out by alternating forward and reverse rotation, with a rotation speed of 200-350 r / min. The direction is changed every 5 minutes, and the mixing time is 30-90 minutes.

[0018] According to the above scheme, the medium static pressure molding pressure in step (2) is between 200-350MPa, and the holding time is 20-50min.

[0019] According to the above scheme, in step (3), the organic solvent used is polyvinyl alcohol or polystyrene, and the solid component content of the mixed slurry is 50-70wt%.

[0020] According to the above scheme, after the sintering of step (4), the coating thickness is 0.8-3mm and the substrate thickness is 8-15mm.

[0021] The present invention relates to the application of the submerged entry nozzle as a continuous casting submerged entry nozzle or a long entry nozzle for aluminum deoxidized steel ladles.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: The substrate and coating of the nozzle of this invention constitute a multiphase lining material. The Fe-Mg-Al-O compound formed generates a liquid protective film on its surface during continuous casting, making it difficult for alumina inclusions in the molten steel to adhere to the inner wall of the nozzle. Furthermore, the good wettability of the Mg-Fe-Al-O compound with the molten steel prevents inclusions such as alumina in the molten steel from adhering to the inner wall of the nozzle. Ultimately, these inclusions are carried into the crystallizer along with the flow of the molten steel, reducing nozzle blockage. In addition, the Mg-Fe-Al-O compound is a dense phase, which can inhibit the diffusion of SiO2 (solid) and C (solid) in the nozzle body into the molten steel, thereby fundamentally inhibiting the reaction of Al in the molten steel to form Al2O3 inclusions.

[0023] This invention employs a dual-layer multiphase structure of matrix and coating to significantly improve the erosion resistance and anti-nodulation performance of submerged entry nozzles. In practical use, when alumina inclusions in the molten steel are adsorbed onto the inner wall of the nozzle, they react immediately with the iron-based powder in the coating to form a low-melting-point phase. This phase is carried into the crystallizer by the steel flow, thus reducing initial adhesion to the nozzle's inner wall. Once the iron-based powder coating is consumed, the phase in the matrix is ​​primarily spinel-based cubic, while the alumina inclusions in the molten steel are trigonal. The high interfacial energy between the two prevents Al2O3 inclusions from easily accumulating on the surface of the lining material during high-temperature operation. The combined use of these two components significantly improves the anti-nodulation capability and service life of submerged entry nozzles.

[0024] The bulk density of the immersion nozzle substrate of this invention is 3.0-3.5 g / cm³. 3 The apparent porosity is 10-15%, the thermal shock stability is >10 times (1100℃-water cooling), the number of consecutive casting furnaces in actual use is 10-15, and the thickness of the alumina coating on the inner wall of the nozzle is less than 3mm after 200 minutes of aluminum-killed steel casting.

[0025] This invention features excellent anti-clogging effect and long service life. It can be applied not only to immersion nozzles in continuous casting, but also to high-temperature industries such as anti-clogging of long nozzles in ladles using aluminum deoxidized steel and anti-nodulation of tundish stoppers. It overcomes the problem of nodulation and clogging of immersion nozzles in the casting process of aluminum deoxidized steel, such as automotive steel sheets, and is expected to be promoted for large-scale production application. Attached Figure Description

[0026] Figure 1 : Schematic diagram of the submersible water inlet structure of the present invention.

[0027] Figure 2 SEM image of the immersion nozzle substrate in Example 2. Detailed Implementation

[0028] The following embodiments further illustrate the technical solution of the present invention, but are not intended to limit the scope of protection of the present invention.

[0029] A specific implementation provides an immersion-type water inlet, the structure of which is as follows: Figure 1 As shown, it includes: an outer layer, a body, a substrate, and a coating layer; the outer layer is a certain thickness of refractory fiber (aluminosilicate fiber or alumina fiber), and the body is aluminum carbon, zirconium carbon, or aluminum zirconium carbon.

[0030] The matrix uses the following raw materials: Main raw materials: 5-10% magnesia (MgO≥95%), 5-10% corundum (Al2O3≥95%), and 60-80% solid solution of magnesium-iron spinel, Mg x Fe y Al 2-x-y O4(x+y≦2), this solid solution includes, but is not limited to, the following forms: MgFe2O4, MgAl2O4, Mg(Fe,Al)2O4, FeAl2O4. The matrix material particle size distribution is as follows: 3-1mm 20-30%, 1-0.5mm 30-40%, 0.5-0.088mm 20-35%, less than 0.088mm 10-15%. Sintering aid 5-10%: one or a combination of andalusite, kyanite, sillimanite, cordierite, zircon, wollastonite, or kaolin. The particle size of the sintering aid is as follows: 1-0.5mm 35-65%, 0.5-0.088mm 35-65%. Carbon source 1-5%; can be natural graphite or artificial graphite (C content greater than 90%).

[0031] An external binder of 1-5 wt% is added; one or a combination of phenolic resin, furan resin and polyvinyl alcohol is used.

[0032] The raw material for the coating layer is 80-90% Fe-based powder and 10-20% additives; the Fe-based powder is selected from one or a combination of FeO powder, Fe2O3 powder or Fe2O3·FeO powder; the additives can be one or a combination of quartz, mullite, zirconium oxide or magnesium aluminum spinel.

[0033] The specific implementation also provides a method for preparing the above-mentioned submersible nozzle: Preparation of the matrix mixture: Select the main materials, sintering aids, carbon source, and binder according to the designed formula composition and particle size distribution. Mix the materials using a planetary ball mill, alternating between forward and reverse rotation at a speed of 200-350 r / min, changing the direction every 5 min, for a total mixing time of 30-90 min.

[0034] The mixed matrix material and the gate body material are laid out in a manner that first places the body material and then the matrix mixture. The mixture is then formed using isostatic pressing at a pressure of 200-350 MPa for 20-50 minutes. After the matrix mixture and gate body material are formed, a coating slurry is applied to the inner wall of the gate. The slurry is dispersed using an organic solvent, such as polyvinyl alcohol or polystyrene, and the solid component content of the mixed slurry is ensured to be 50-70%.

[0035] Immersion nozzles are prepared using nitrogen protection, argon protection, or carbon sintering. The final sintering temperature is 1450~1550℃, and the holding time is 2-6h. After sintering, the coating material thickness must be 0.8-3mm, and the substrate mixture layer thickness must be 8-15mm.

[0036] Finally, the prefabricated refractory fibers are bound to the outside of the nozzle body with a high-temperature adhesive to form an outer insulation structure, thus obtaining an immersion nozzle.

[0037] Example 1 The main raw materials of the matrix are: 6% magnesia, 8% corundum, and 76% solid solution of magnesium-iron spinel, which is composed of MgFe2O4, MgAl2O4, and FeAl2O4 in a 2:1:1 ratio. The particle size distribution of the matrix material is as follows: 3-1mm 20%, 1-0.5mm 35%, 0.5-0.088mm 30%, and less than 0.088mm 15%; 8% sintering aid: composed of andalusite, cordierite, wollastonite, and kaolin in a 4:2:1:1 ratio. The particle size distribution of the sintering aid is as follows: 1-0.5mm 60%, 0.5-0.088mm 40%; carbon source: 2% natural graphite (92% C content); binder: 3.5% added, the binder is phenolic resin.

[0038] Coating slurry preparation: 85% Fe-based powder, which is selected from FeO powder and Fe2O3 powder in a 1:1 ratio; 15% additives, which are selected from quartz, mullite and magnesium aluminum spinel in a 1:4:4 ratio; the slurry is dispersed using polyvinyl alcohol organic solvent, and the mixed slurry ensures that the solid component content is 55%.

[0039] The outer layer is 10mm thick aluminum silicate refractory fiber, and the body is aluminum zirconium carbon material with a thickness of 30mm.

[0040] Preparation of the matrix mixture: The main materials, sintering aids, carbon source, and binder were selected according to the designed formula and particle size distribution. A planetary ball mill was used for mixing, alternating between forward and reverse rotation at a speed of 265 r / min, changing direction every 5 minutes, for a total mixing time of 70 minutes.

[0041] The mixed matrix material and the nozzle body material are laid out in a manner that first places the body material and then the matrix mixture. The mixture is then formed using isostatic pressing at a pressure of 275 MPa for 35 minutes. After the matrix mixture and nozzle body material have been formed, a surface slurry is applied to the inner wall of the composite nozzle.

[0042] Subsequently, the immersion nozzle was prepared by nitrogen-protected sintering. The final sintering temperature was 1520℃ and the holding time was 2.5h. After sintering, the coating material thickness was 1.5mm and the substrate mixture layer was 10mm.

[0043] After the main body and the multiphase lining composite material are sintered, the pre-made refractory fiber is then bound to the outside of the nozzle body with a high-temperature adhesive to form an outer insulation structure, ultimately resulting in a clog-resistant multiphase immersion nozzle that can be practically produced.

[0044] Sprue performance testing: The bulk density of this type of multiphase material matrix was tested to be 3.25 g / cm³. 3 The apparent porosity is 12.5%, the thermal shock resistance is 15 cycles (1100℃-water cooling), the number of consecutive castings in actual use is 12, and the thickness of the alumina coating on the inner wall of the nozzle is 1.2mm after 200 minutes of aluminum-killed steel casting.

[0045] Example 2 Main raw materials: 5% magnesia, 9% corundum, and 78% solid solution of magnesium-iron spinel, which is composed of MgFe2O4 and FeAl2O4 in a 1:1 ratio. The matrix material particle size distribution is as follows: 3-1mm 25%, 1-0.5mm 35%, 0.5-0.088mm 25%, and less than 0.088mm 15%; 5% sintering aid: composed of andalusite, cordierite, zircon, and wollastonite in a 3:2:1:1 ratio. The sintering aid particle size distribution is as follows: 1-0.5mm 50%, 0.5-0.088mm 50%; Carbon source: 3% natural graphite (91% C content); Binder: 3.5% added, the binder is furan resin.

[0046] Coating slurry preparation: 80% Fe-based powder, which is selected from FeO powder and Fe2O3 powder in a 2:1 ratio; 20% additives, which are selected from mullite, zirconium oxide and magnesium aluminum spinel in a 2:1:1 ratio; the slurry is dispersed using polyvinyl alcohol organic solvent, and the mixed slurry ensures that the solid phase component content is 60%.

[0047] The outer layer is 15mm thick alumina refractory fiber, and the body is aluminum carbon with a thickness of 35mm.

[0048] Preparation of the matrix mixture: The main materials, sintering aids, carbon source, and binder were selected according to the designed formula and particle size distribution. A planetary ball mill was used for mixing, alternating between forward and reverse rotation at a speed of 300 r / min, changing direction every 5 minutes, for a total mixing time of 45 minutes.

[0049] The mixed matrix material and the nozzle body material are laid out in a manner that first places the body material and then the matrix mixture. The mixture is then formed using isostatic pressing at a pressure of 310 MPa for 40 minutes. After the matrix mixture and nozzle body material have been formed, a surface slurry is applied to the inner wall of the composite nozzle.

[0050] Subsequently, an immersion nozzle was prepared by argon-protected sintering. The final sintering temperature was 1500℃ and the holding time was 3.5h. After sintering, the coating material thickness was required to be 1.8mm and the substrate mixture layer thickness was required to be 12mm.

[0051] After the main body and the multiphase lining composite material are sintered, the pre-made refractory fiber is then bound to the outside of the nozzle body with a high-temperature adhesive to form an outer insulation structure, ultimately resulting in a clog-resistant multiphase immersion nozzle that can be practically produced.

[0052] Performance testing of the anti-clogging lining material: The bulk density of this type of multiphase material matrix was tested to be 3.34 g / cm³. 3 The apparent porosity is 11.5%, the thermal shock resistance is 13 cycles (1100℃-water cooling), the number of consecutive castings in actual use is 14, and the thickness of the alumina coating on the inner wall of the nozzle is 0.8mm after 200 minutes of aluminum-killed steel casting.

[0053] Example 3 Main raw materials: 8% magnesia, 7% corundum, and 75% solid solution of magnesium-iron spinel, which is composed of MgFe2O4, Mg(Fe,Al)2O4, and FeAl2O4 in a 3:1:1 ratio. The particle size distribution of the matrix material is as follows: 3-1mm 28%, 1-0.5mm 35%, 0.5-0.088mm 27%, and less than 0.088mm 10%. Sintering aid 8%: composed of kyanite, cordierite, and kaolin in a 3:2:1 ratio. The particle size distribution of the sintering aid is as follows: 1-0.5mm 45%, 0.5-0.088mm 55%. Carbon source: 4% artificial graphite (93% C content). Binder: 4.5% added, the binder is composed of phenolic resin and polyvinyl alcohol in a 5:1 ratio.

[0054] Coating slurry preparation: 90% Fe-based powder, which is selected from FeO powder and Fe2O3 powder in a 1:1 ratio; 10% additives, which are selected from mullite, zirconium oxide and magnesium aluminum spinel in a 1:1:1 ratio; the slurry is dispersed using polyvinyl alcohol organic solvent, and the mixed slurry ensures that the solid component content is 65%.

[0055] The outer layer is made of 15mm thick aluminum silicate fiber, and the body is made of zirconium carbon with a thickness of 35mm.

[0056] Preparation of the matrix mixture: The main materials, sintering aids, carbon source, and binder were selected according to the designed formula and particle size distribution. A planetary ball mill was used for mixing, alternating between forward and reverse rotation at a speed of 320 r / min, changing direction every 5 minutes, for a total mixing time of 65 minutes.

[0057] The mixed matrix material and the nozzle body material are laid out in a manner that first places the body material and then the matrix mixture. The mixture is then formed using isostatic pressing at a pressure of 300 MPa for 40 minutes. After the matrix mixture and nozzle body material have been formed, a surface slurry is applied to the inner wall of the composite nozzle.

[0058] Subsequently, the immersion nozzle was prepared by nitrogen-protected sintering. The final sintering temperature was 1480℃ and the holding time was 4.5h. After sintering, the coating material thickness was 1.6mm and the substrate mixture layer thickness was 14mm.

[0059] After the main body and the multiphase lining composite material are sintered, the pre-made refractory fiber is then bound to the outside of the nozzle body with a high-temperature adhesive to form an outer insulation structure, ultimately resulting in a clog-resistant multiphase immersion nozzle that can be practically produced.

[0060] Performance testing of the anti-clogging lining material: The bulk density of this type of multiphase material matrix was tested to be 3.1 g / cm³. 3 The apparent porosity is 14.5%, the thermal shock resistance is 18 cycles (1100℃-water cooling), the number of consecutive casting furnaces in actual use is 11, and the thickness of the alumina coating on the inner wall of the nozzle is 2.4mm after 200 minutes of aluminum-killed steel casting.

[0061] Example 4 Main raw materials: 7% magnesia, 7% corundum, and 74% solid solution of magnesium-iron spinel, which is composed of MgFe2O4, MgAl2O4, and FeAl2O4 in a 3:1:1 ratio. The particle size distribution of the matrix material is as follows: 30% 3-1mm, 30% 1-0.5mm, 30% 0.5-0.088mm, and 10% less than 0.088mm. Sintering aid 8%: composed of kyanite, sillimanite, cordierite, zircon, and kaolin in a 3:3:2:1:1 ratio. The particle size distribution of the sintering aid is as follows: 40% 1-0.5mm, 60% 0.5-0.088mm. Carbon source: 4% natural graphite (92% C content). Binder: 4% added, the binder is a 1:1 mixture of phenolic resin and furan resin.

[0062] Coating slurry preparation: 80% Fe-based powder, which is selected from FeO powder, Fe2O3 powder and Fe2O3·FeO in a 1:1:1 ratio; 20% additives, which are selected from quartz, mullite and zirconium oxide in a 1:1:1 ratio; the slurry is dispersed using polyvinyl alcohol organic solvent, and the mixed slurry ensures that the solid component content is 65%.

[0063] The outer layer is made of 12mm thick aluminum silicate fiber, and the body is made of aluminum zirconium carbon with a thickness of 35mm.

[0064] Preparation of the matrix mixture: The main materials, sintering aids, carbon source, and binder were selected according to the designed formula and particle size distribution. A planetary ball mill was used for mixing, alternating between forward and reverse rotation at a speed of 330 r / min, changing direction every 5 minutes, for a total mixing time of 35 minutes.

[0065] The mixed matrix material and the nozzle body material are laid out in a manner that first places the body material and then the matrix mixture. The mixture is then formed using isostatic pressing at a pressure of 245 MPa for 40 minutes. After the matrix mixture and nozzle body material have been formed, a surface slurry is applied to the inner wall of the composite nozzle.

[0066] Subsequently, the immersion nozzle was prepared by nitrogen-protected sintering. The final sintering temperature was 1535℃ and the holding time was 3h. After sintering, the coating material thickness was 2.5mm and the substrate mixture layer was 10mm.

[0067] After the main body and the multiphase lining composite material are sintered, the pre-made refractory fiber is then bound to the outside of the nozzle body with a high-temperature adhesive to form an outer insulation structure, ultimately resulting in a clog-resistant multiphase immersion nozzle that can be practically produced.

[0068] Performance testing of the anti-clogging lining material: The bulk density of this type of multiphase material matrix was tested to be 3.05 g / cm³. 3 The apparent porosity is 14.5%, the thermal shock resistance is 11 cycles (1100℃-water cooling), the number of consecutive casting furnaces in actual use is 10, and the thickness of the alumina coating on the inner wall of the nozzle is 2.8mm after 200 minutes of aluminum-killed steel casting.

Claims

1. A submersible sprue, characterized in that... From the outside in, the layers are: outer layer, body, substrate, and coating layer. The matrix, by mass percentage, consists of: 5-10% magnesia, 5-10% corundum, 70-80% solid solution of magnesium-iron spinel, 5-10% sintering aid, 1-5% carbon, and 1-5 wt% binder, which are mixed and sintered together. The coating layer is formed by sintering 80-90% iron-based powder and 10-20% additives by mass percentage.

2. The submersible sprue as described in claim 1, characterized in that... The solid solution of the magnesium-iron spinel is represented as Mg x Fe y Al 2-x-y O4(x+y≦2), the solid solution includes the following forms: MgFe2O4, MgAl2O4, Mg(Fe,Al)2O4, FeAl2O4.

3. The immersion-type water inlet as described in claim 1, characterized in that... The solid solution particle size distribution of the magnesia, corundum, and magnesium-iron spinel is as follows: 3-1mm 20-30%, 1-0.5mm 30-40%, 0.5-0.088mm 20-35%, and less than 0.088mm 10-15%.

4. The immersion-type water inlet as described in claim 1, characterized in that... The sintering aid is one or a combination of several of the following: andalusite, kyanite, sillimanite, cordierite, zircon, wollastonite, and kaolin; the particle size is as follows: 1-0.5mm 35-65%, 0.5-0.088mm 35-65%.

5. The immersion-type water inlet as described in claim 1, characterized in that... The binder is one or a combination of phenolic resin, furan resin, and polyvinyl alcohol.

6. The submersible sprue as described in claim 1, characterized in that... The iron-based powder is one or a combination of FeO powder, Fe2O3 powder, and Fe2O3·FeO powder.

7. The submersible sprue as described in claim 1, characterized in that... The additive is one or a combination of several of the following: quartz, mullite, zirconium oxide, and magnesium aluminum spinel.

8. The method for preparing the submersible sprue according to claim 1, characterized in that... Includes the following steps: (1) Select the raw materials of the matrix according to the design composition and particle size distribution and mix them to obtain the matrix mixture; (2) The material is laid out in the manner of first arranging the main body and then arranging the base mixture, and isostatic pressing is used for molding; (3) The raw materials for the coating layer are dispersed in an organic solvent to obtain a coating slurry, which is then coated on the inside of the sprue substrate; (4) Under a protective atmosphere, heat to 1450~1550℃ and sinter for 2-6 hours; (5) The prefabricated refractory fiber is bound to the outside of the nozzle body with a high-temperature adhesive.

9. The method for preparing the submersible sprue as described in claim 8, characterized in that... In step (1), a planetary ball mill is used for mixing. The mixing is carried out by alternating forward and reverse rotation at a speed of 200-350 r / min. The direction is changed every 5 min, and the mixing time is 30-90 min. In step (2), the hydrostatic pressing pressure is between 200-350 MPa, and the holding time is 20-50 min. In step (3), the organic solvent used is polyvinyl alcohol or polystyrene, and the solid component content of the mixed slurry is 50-70 wt%. In step (4), after sintering, the coating thickness is 0.8-3 mm, and the substrate thickness is 8-15 mm.

10. The application of the submerged entry nozzle as described in claim 1 as a continuous casting submerged entry nozzle or a long entry nozzle for aluminum deoxidized steel ladles.

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