In-situ reinforced lightweight porous corundum-based castable and preparation method thereof

Abstract

This invention relates to the field of refractory castables, specifically disclosing an in-situ reinforced lightweight porous corundum refractory castable and its preparation method. By introducing Al2O3 hollow spheres and nano-Al2O3 into the corundum refractory castable, and by introducing a specific dispersant, the Al2O3 hollow spheres and nano-Al2O3 can be uniformly dispersed in the castable system, reducing the bulk density of the castable and increasing its apparent porosity. The porous structure effectively blocks heat conduction, reducing heat loss in high-temperature equipment, thereby achieving energy-saving and environmentally friendly effects. Furthermore, the whisker reinforcement effect of nano-alumina allows the castable to maintain high room-temperature compressive strength and room-temperature flexural strength. Due to the reasonable particle size distribution of the raw materials used in this invention, the castable can achieve close packing, improving material performance. Therefore, this invention has the advantages of simple process, low cost, energy saving, and environmental protection.

Description

Technical Field

[0001] This invention relates to the field of refractory castable technology, specifically to an in-situ reinforced lightweight porous corundum refractory castable and its preparation method. Background Technology

[0002] With the implementation of the dual-carbon strategy, China's modern industrial system is undergoing a developmental transformation centered on "green, low-carbon, and high-quality" development, leading to increasingly stringent requirements for energy conservation and environmental protection. This places even greater demands on the performance of lightweight porous refractory materials. Corundum castables are widely used in high-temperature industries, particularly in high-temperature furnace linings, ladle linings, and tundish linings. However, traditional corundum castables, due to their dense structure, exhibit high thermal conductivity, increasing heat loss and energy consumption in high-temperature equipment. Therefore, developing a lightweight porous corundum castable that possesses both high-temperature stability and effective energy conservation is of great significance for achieving industrial energy conservation and reducing carbon emissions.

[0003] The lightweight and porous nature of corundum refractory castables can be achieved by optimizing the selection and proportioning of aggregates, or by adding pore-forming agents, employing foaming technology, or introducing nanomaterials. This creates a uniformly distributed pore structure within the corundum castable, which effectively blocks heat conduction and reduces heat loss in high-temperature equipment. Therefore, the preparation methods of lightweight and porous refractory castables are attracting increasing attention.

[0004] The patented technology, "A Preparation Method of Lightweight Porous Mullite Refractory Castable" (CN201410166002.8), improves the performance of mullite refractory castable by changing the amount of lightweight porous mullite aggregate, resulting in a refractory castable with a bulk density of 1.55 g / cm³. -3 The compressive strength at room temperature can reach 6.9 MPa; the patented technology of "A lightweight aluminosilicate refractory castable and its preparation method" (CN202010922488.9) uses alumina ash ceramic spheres as aggregate to prepare a refractory with a bulk density of 1.29 g / cm³. 2Lightweight refractory castables with a room temperature compressive strength of 18 MPa; the patented technology of "A lightweight cordierite castable and its preparation method" (CN201210272265.8) prepares lightweight cordierite castables with an average pore size of 20~30 μm and a flexural strength of 5~10 MPa by changing the amount of porous cordierite ceramic particle aggregate added. The above methods optimize the aggregate design to produce lightweight porous refractory castables, but the room temperature strength of these refractory castables is not high. The patented technology "A Preparation Method of a Novel Mullite-Bound Lightweight Castable" (CN202210515577.0) involves pulverizing porous mullite powder and other raw materials, mixing them multiple times, sieving them, and then drying them. The resulting novel mullite-bound lightweight castable has a high compressive strength of 69.29 MPa. The patented technology "A Refractory Castable" (CN202411304336.7) involves impregnating porous kaolinite lightweight aggregate and mullite aggregate in different proportions with phenolic resin before casting. The resulting castable has a bulk density of 1.98 g / cm³. -3 The compressive strength is 53.9 MPa. The patented technology of "Steel Fiber Reinforced Castable" (CN201210100617.1) enhances the strength of the castable by adding external steel fibers, achieving a compressive strength of 60.7 MPa after post-treatment at 1500℃. While the above patent increases the room-temperature strength of the castable by adding fibers, this method is relatively complex and costly.

[0005] In summary, to meet the energy-saving and environmental protection requirements of modern light industry, it is necessary to prepare a lightweight and porous corundum refractory castable. However, lightweight and porous materials will have a certain impact on the strength of the material. Therefore, it is necessary to maintain high room temperature strength while designing a lightweight and porous corundum refractory castable. Summary of the Invention

[0006] The present invention aims to overcome the defects of the prior art and provides an in-situ reinforced lightweight porous corundum refractory castable and its preparation method. The corundum refractory castable prepared by this method generates alumina whiskers in situ, and maintains high room temperature compressive strength and flexural strength under low bulk density and high apparent porosity.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution: an in-situ reinforced lightweight porous corundum refractory castable, wherein the raw materials of the castable and their respective mass percentages include: 40%~60% corundum particles, 20%~40% corundum micro powder, 0%~10% α-Al2O3 fine powder, 5%~50% Al2O3 hollow spheres, 0%~10% ρ-Al2O3 micro powder, 0%~10% nano Al2O3, 0%~10% dispersant, and 0%~10% water.

[0008] Ideally, the particle size of the corundum micro powder is 0~500μm, the particle size of the corundum particles is 0~10mm, and the Al2O3 content in both the corundum micro powder and the corundum particles is above 90%.

[0009] More preferably, the particle size of the Al2O3 hollow spheres is 0~5mm; the particle size of the α-Al2O3 fine powder is 0~0.15mm; the particle size of the ρ-Al2O3 micro powder is 0~0.088mm; and the particle size of the nano Al2O3 is 0~100nm.

[0010] More preferably, the dispersant is a water-reducing agent or sodium tripolyphosphate (Na3P3O4). 10 Sodium hexametaphosphate (NaPO) 11 (n, n=14~40) or one or more combinations thereof.

[0011] More preferably, the water-reducing agent is any one or more combinations of FS10, FS20, and FS60.

[0012] More preferably, the castable further includes alumina fibers and polypropylene fibers, wherein the amount of alumina fibers added is 0.1% to 2% of the total mass of the castable; and the amount of polypropylene fibers added is 0.05% to 0.15% of the total mass of the castable.

[0013] In a more optimized manner, the alumina fibers undergo surface modification, specifically through the following steps: Step S1: Place the alumina fiber in a mixed acid solution and sonicate for 10 min to 15 min, then treat it in a water bath at 60℃ to 65℃ for 1 h to 1.5 h, wash it with deionized water, and dry it to obtain the pretreated fiber. Step S2: Mix ammonium molybdate tetrahydrate, aluminum chloride hexahydrate, and silica sol, dissolve in deionized water to obtain an impregnation solution; place the pretreated fiber in the impregnation solution, vacuum impregnate for 30 min to 40 min, freeze dry at -80℃ for 12 h to 16 h, then heat to 800℃ to 820℃ at a rate of 5℃ / min to 6℃ / min, then heat to 900℃ to 920℃ at a rate of 1℃ / min to 2℃ / min, hold for 1 to 2 h, and cool naturally to obtain surface-modified alumina fiber.

[0014] In a more optimized manner, in step S1, the mixed acid solution is a mixture of hydrochloric acid and sulfuric acid in a volume ratio of 1:1; in step S2, the mass ratio of ammonium molybdate tetrahydrate, aluminum chloride hexahydrate, and silica sol is (5~7) (120~125): (8~10); and the pressure during vacuum impregnation is 0.01MPa~0.04MPa.

[0015] In a more optimized manner, according to the above-described method for preparing an in-situ reinforced lightweight porous corundum refractory castable, the specific steps are as follows: weigh the raw material powder according to the proportion, stir for 3 min to 5 min, then add water, continue stirring for 3 min to 5 min, finally pour the mixture into a mold and vibrate to form it, cure at room temperature for 12 h to 36 h, and then demold to obtain the corundum refractory castable.

[0016] Compared with the prior art, the beneficial effects achieved by the present invention are: 1. This invention introduces hollow Al2O3 spheres and nano-Al2O3 into corundum refractory castables, and through the introduction of a specific dispersant, ensures that the hollow Al2O3 spheres and nano-Al2O3 are uniformly dispersed in the castable system. This reduces the bulk density of the castable and increases its apparent porosity. The porous structure effectively blocks heat conduction, reducing heat loss from high-temperature equipment, thus achieving energy-saving and environmentally friendly effects. Furthermore, the whisker reinforcement effect of nano-alumina allows the castable to maintain high room-temperature compressive strength and flexural strength. Due to the reasonable particle size distribution of the raw materials used in this invention, the castable can achieve close packing, improving material performance. Therefore, this invention has the advantages of simple process, low cost, energy saving, and environmental protection. The resulting castable, through in-situ generation of alumina whiskers, maintains high room-temperature compressive strength and flexural strength with relatively low bulk density and relatively high apparent porosity.

[0017] 2. This invention improves the thermal shock resistance of corundum refractory castables by introducing polypropylene fibers and alumina fibers. To avoid the introduction of polypropylene fibers and alumina fibers affecting the room temperature flexural strength of the product, the method limits the addition amount of alumina fibers to 0.1%~2% of the total mass of the castable; the addition amount of polypropylene fibers to 0.05%~0.15% of the total mass of the castable. Preferably, the addition amount of alumina fibers is 0.5% of the total mass of the castable; the addition amount of polypropylene fibers is 0.08% of the total mass of the castable. At this dosage, the room temperature flexural strength of the product does not decrease significantly, and the thermal shock resistance is improved.

[0018] 3. Based on the above scheme, the present invention further adjusts the formula. In order to reduce the impact of the introduction of alumina fibers on the flexural strength, the present invention performs surface modification on alumina and generates mullite whiskers on the surface of alumina fibers through steps such as vacuum impregnation and freeze drying, so as to improve the interfacial bonding performance between alumina fibers and refractory materials. At the same time, the presence of mullite whiskers will also improve the mechanical properties of the product. Attached Figure Description

[0019] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a SEM image of the lightweight porous corundum refractory castable prepared in Example 2 of the present invention; Figure 2 This is a TEM image of the lightweight porous corundum refractory castable prepared in Example 2 of the present invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] In this embodiment, it should be noted that there are no special restrictions on the manufacturers of the raw materials involved in this invention. Exemplarily, the following materials are included: the corundum micro powder has a particle size of 0-500 μm, the corundum particles have a particle size of 0-10 mm, and the Al2O3 content in both the corundum micro powder and corundum particles is above 90%. The Al2O3 hollow spheres have a particle size of 0-5 mm; the α-Al2O3 fine powder has a particle size of 0-0.15 mm; the ρ-Al2O3 micro powder has a particle size of 0-0.088 mm; and the nano-Al2O3 has a particle size of 0-100 nm. The alumina fiber is of the Moron 735 type; the polypropylene fiber has a density of 0.09-0.92 g × cm⁻¹. -3 It has a melting point of 165~173℃ and a length of 1.5~200mm.

[0022] Example 1 An in-situ reinforced lightweight porous corundum refractory castable is prepared by the following steps: The raw materials and their respective mass percentages include: 42% wt% corundum particles, 32 wt% corundum micro powder, 7.5 wt% α-Al2O3 fine powder, 5 wt% Al2O3 hollow spheres, 7 wt% ρ-Al2O3 micro powder, 1.5 wt% nano Al2O3, 0.2 wt% dispersant, and the balance being water (190 ml). The dispersant is FS10.

[0023] First, weigh the powder according to the formula, then pour it into a mixing pot and stir for 3 minutes. Next, add water to the mixing pot and continue stirring for 3 minutes. Finally, pour the mixture into a mold and vibrate it to form the desired shape. After curing at room temperature for 24 hours, demold the mixture to obtain a corundum refractory castable.

[0024] Tests showed that the bulk density and apparent porosity of the corundum refractory castable obtained in this embodiment after heat treatment at 1500℃ were 2.47 g / cm³. 3The compressive strength and flexural strength at room temperature are 60.1 MPa and 10.30 MPa, respectively, with an increase of 30%.

[0025] Example 2 An in-situ reinforced lightweight porous corundum refractory castable is prepared by the following steps: The raw materials and their respective mass percentages include: 42% wt% corundum particles, 27 wt% corundum micro powder, 7.5 wt% α-Al2O3 fine powder, 10 wt% Al2O3 hollow spheres, 7 wt% ρ-Al2O3 micro powder, 1.5 wt% nano Al2O3, 0.2 wt% dispersant, and the balance being water (190 ml). The dispersant is FS10.

[0026] First, weigh the powder according to the formula, then pour it into a mixing pot and stir for 3 minutes. Next, add water to the mixing pot and continue stirring for 3 minutes. Finally, pour the mixture into a mold and vibrate it to form the desired shape. After curing at room temperature for 24 hours, demold the mixture to obtain a corundum refractory castable.

[0027] Tests showed that the bulk density and apparent porosity of the corundum refractory castable obtained in this embodiment after heat treatment at 1500℃ were 2.38 g / cm³. -3 The strength and flexural strength at room temperature are 39%, with compressive strength and flexural strength at room temperature of 70.40 MPa and 13.37 MPa, respectively.

[0028] Example 3 An in-situ reinforced lightweight porous corundum refractory castable is prepared by the following steps: The raw materials and their respective mass percentages include: 42% wt% corundum particles, 22 wt% corundum micro powder, 7.5 wt% α-Al2O3 fine powder, 15 wt% Al2O3 hollow spheres, 7 wt% ρ-Al2O3 micro powder, 1.5 wt% nano Al2O3, 0.2 wt% dispersant, and the balance being water (190 ml). The dispersant is FS10.

[0029] First, weigh the powder according to the formula, then pour it into a mixing pot and stir for 3 minutes. Next, add water to the mixing pot and continue stirring for 3 minutes. Finally, pour the mixture into a mold and vibrate it to form the desired shape. After curing at room temperature for 24 hours, demold the mixture to obtain a corundum refractory castable.

[0030] Tests showed that the bulk density and apparent porosity of the corundum refractory castable obtained in this embodiment after heat treatment at 1500℃ were 2.17 g / cm³. -3 The strength is 42%, and the compressive strength and flexural strength at room temperature are 39.10 MPa and 12.50 MPa, respectively.

[0031] Using Example 2 as the experimental group, optimization experiments were conducted based on Example 2, as detailed in Examples 4-7.

[0032] Example 4 An in-situ reinforced lightweight porous corundum refractory castable is prepared by the following steps: The raw materials and their respective mass percentages include: 42% wt% corundum particles, 27 wt% corundum micro powder, 7.5 wt% α-Al₂O₃ fine powder, 10 wt% Al₂O₃ hollow spheres, 7 wt% ρ-Al₂O₃ micro powder, 1.5 wt% nano Al₂O₃, 0.2 wt% dispersant, 0.5% alumina fiber, 0.08% polypropylene fiber, and the balance being water. The dispersant is FS10.

[0033] Weigh the raw material powder according to the formula, stir for 3 minutes, add water, continue stirring for 3 minutes, and finally pour the mixture into the mold and vibrate to form it. After curing at room temperature for 24 hours, demold to obtain the corundum refractory castable.

[0034] Example 5 An in-situ reinforced lightweight porous corundum refractory castable is prepared by the following steps: The raw materials and their respective mass percentages include: 42% wt% corundum particles, 27 wt% corundum micro powder, 7.5 wt% α-Al₂O₃ fine powder, 10 wt% Al₂O₃ hollow spheres, 7 wt% ρ-Al₂O₃ micro powder, 1.5 wt% nano Al₂O₃, 0.2 wt% dispersant, 0.5% alumina fiber, 0.08% polypropylene fiber, and the balance being water. The dispersant is FS10.

[0035] Weigh the raw material powder according to the formula, stir for 3 minutes, add water, continue stirring for 3 minutes, and finally pour the mixture into the mold and vibrate to form it. After curing at room temperature for 24 hours, demold to obtain the corundum refractory castable.

[0036] The alumina fibers undergo surface modification, specifically through the following steps: Step S1: Place the alumina fiber in a mixed acid solution and sonicate for 10 min, then treat it in a water bath at 60°C for 1.5 h, wash it with deionized water, and dry it to obtain the pretreated fiber; the mixed acid solution is a mixture of hydrochloric acid and sulfuric acid in a volume ratio of 1:1, with pH=1; Step S2: Mix ammonium molybdate tetrahydrate, aluminum chloride hexahydrate, and silica sol, dissolve in deionized water to obtain an impregnation solution; place the pretreated fiber in the impregnation solution, vacuum impregnate for 30 min, freeze-dry at -80℃ for 12 h, then heat to 800℃ at a rate of 5℃ / min, then heat to 900℃ at a rate of 1℃ / min, hold for 2 h, and cool naturally to obtain surface-modified alumina fiber. The mass ratio of ammonium molybdate tetrahydrate, aluminum chloride hexahydrate, and silica sol is 7:120:10; the pressure during vacuum impregnation is 0.01 MPa.

[0037] Example 6 An in-situ reinforced lightweight porous corundum refractory castable is prepared by the following steps: The raw materials and their respective mass percentages include: 42% wt% corundum particles, 27 wt% corundum micro powder, 7.5 wt% α-Al₂O₃ fine powder, 10 wt% Al₂O₃ hollow spheres, 7 wt% ρ-Al₂O₃ micro powder, 1.5 wt% nano Al₂O₃, 0.2 wt% dispersant, 0.5% alumina fiber, 0.08% polypropylene fiber, and the balance being water. The dispersant is FS10.

[0038] Weigh the raw material powder according to the formula, stir for 3 minutes, add water, continue stirring for 3 minutes, and finally pour the mixture into the mold and vibrate to form it. After curing at room temperature for 24 hours, demold to obtain the corundum refractory castable.

[0039] The alumina fibers undergo surface modification, specifically through the following steps: Step S1: Place the alumina fiber in a mixed acid solution and sonicate for 12 min, then treat it in a water bath at 65°C for 1.2 h, wash it with deionized water, and dry it to obtain the pretreated fiber; the mixed acid solution is a mixture of hydrochloric acid and sulfuric acid in a volume ratio of 1:1, with pH=1; Step S2: Mix ammonium molybdate tetrahydrate, aluminum chloride hexahydrate, and silica sol, dissolve in deionized water to obtain an impregnation solution; place the pretreated fiber in the impregnation solution, vacuum impregnate for 35 min, freeze-dry at -80℃ for 15 h, then heat to 810℃ at a rate of 5℃ / min, then heat to 910℃ at a rate of 1℃ / min, hold for 1.5 h, and allow to cool naturally to obtain surface-modified alumina fiber. The mass ratio of ammonium molybdate tetrahydrate, aluminum chloride hexahydrate, and silica sol is 7:120:10; the pressure during vacuum impregnation is 0.01 MPa.

[0040] Example 7 An in-situ reinforced lightweight porous corundum refractory castable is prepared by the following steps: The raw materials and their respective mass percentages include: 42% wt% corundum particles, 27 wt% corundum micro powder, 7.5 wt% α-Al₂O₃ fine powder, 10 wt% Al₂O₃ hollow spheres, 7 wt% ρ-Al₂O₃ micro powder, 1.5 wt% nano Al₂O₃, 0.2 wt% dispersant, 0.5% alumina fiber, 0.08% polypropylene fiber, and the balance being water. The dispersant is FS10.

[0041] Weigh the raw material powder according to the formula, stir for 3 minutes, add water, continue stirring for 3 minutes, and finally pour the mixture into the mold and vibrate to form it. After curing at room temperature for 24 hours, demold to obtain the corundum refractory castable.

[0042] The alumina fibers undergo surface modification, specifically through the following steps: Step S1: Place the alumina fiber in a mixed acid solution and sonicate for 15 min, then treat it in a water bath at 65°C for 1 h, wash it with deionized water, and dry it to obtain the pretreated fiber; the mixed acid solution is a mixture of hydrochloric acid and sulfuric acid in a volume ratio of 1:1, with pH=1; Step S2: Mix ammonium molybdate tetrahydrate, aluminum chloride hexahydrate, and silica sol, dissolve in deionized water to obtain an impregnation solution; place the pretreated fiber in the impregnation solution, vacuum impregnate for 40 min, freeze-dry at -80℃ for 16 h, then heat to 820℃ at a rate of 5℃ / min, then heat to 920℃ at a rate of 1℃ / min, hold at that temperature for 1.5 h, and allow to cool naturally to obtain surface-modified alumina fiber. The mass ratio of ammonium molybdate tetrahydrate, aluminum chloride hexahydrate, and silica sol is 7:120:10; the pressure during vacuum impregnation is 0.01 MPa.

[0043] Testing experiment: 1. The bulk density and apparent porosity of the specimen after heat treatment at 1500℃ shall be tested according to the method disclosed in GB / T2997; the flexural strength of the specimen at room temperature shall be tested according to the method disclosed in GB / T3001; and the compressive strength of the specimen at room temperature shall be tested according to the method disclosed in GB / T5072.

[0044] 2. Thermal shock resistance: Referring to the air quenching method disclosed in GB / T30873, the sample was kept at 1100℃ for 15 min and then air-cooled to room temperature. This cycle was repeated 3 times. The room temperature flexural strength of the sample after thermal shock was tested, and the strength retention rate was calculated.

[0045]

[0046] Conclusions: 1. Nano-Al2O3 has a large specific surface area and high activity. Its addition to corundum-based refractory castables can significantly promote the sintering of the matrix. Figure 1The SEM image shows that a large number of needle-like alumina whiskers were produced in situ in the corundum refractory castable at a heat treatment temperature of 1500 ℃. Figure 2 TEM images clearly show alumina grains with an interplanar spacing of 0.226 nm. The formation of alumina whiskers significantly improves the room temperature compressive strength and room temperature flexural strength of the castable. Furthermore, the low density of Al2O3 hollow spheres, when added to corundum refractory castables, significantly reduces the bulk density and increases the apparent porosity. Although the addition of Al2O3 hollow spheres slightly reduces the room temperature strength of the castable, its porous structure hinders crack propagation, thus maintaining high strength at high temperatures.

[0047] 2. Comparing Example 1 and Example 2, it can be found that the room temperature flexural strength of Example 2 after heat treatment at 1500℃ increased by 20.1%, the room temperature compressive strength increased by 17.1%, the apparent porosity decreased by 30%, and the bulk density increased by 4.5%. However, the room temperature strength of Example 3 after heat treatment at 1500℃ decreased significantly. This indicates that the addition of 10% alumina hollow spheres yields the best results.

[0048] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0049] Finally, it should be noted that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An in-situ reinforced lightweight porous corundum refractory castable, characterized in that: The raw materials of the castable and their respective mass percentages include: 40%~60% corundum particles, 20%~40% corundum micro powder, 0%~10% α-Al2O3 fine powder, 5%~50% Al2O3 hollow spheres, 0%~10% ρ-Al2O3 micro powder, 0%~10% nano Al2O3, 0%~10% dispersant, and 0%~10% water.

2. The in-situ reinforced lightweight porous corundum refractory castable according to claim 1, characterized in that: The particle size of the corundum micro powder is 0~500μm, and the particle size of the corundum particles is 0~10mm. The content of Al2O3 in both the corundum micro powder and the corundum particles is above 90%.

3. The in-situ reinforced lightweight porous corundum refractory castable according to claim 1, characterized in that: The particle size of the hollow Al2O3 spheres is 0~5mm; the particle size of the α-Al2O3 fine powder is 0~0.15mm; the particle size of the ρ-Al2O3 micro powder is 0~0.088mm; and the particle size of the nano Al2O3 is 0~100nm.

4. The in-situ reinforced lightweight porous corundum refractory castable according to claim 1, characterized in that: The dispersant is one or more of the following: water-reducing agent, sodium tripolyphosphate, and sodium hexametaphosphate.

5. The in-situ reinforced lightweight porous corundum refractory castable according to claim 4, characterized in that: The water-reducing agent is any one or more combinations of FS10, FS20, and FS60.

6. The in-situ reinforced lightweight porous corundum refractory castable according to claim 1, characterized in that: The castable also includes alumina fibers and polypropylene fibers, wherein the amount of alumina fibers added is 0.1% to 2% of the total mass of the castable; and the amount of polypropylene fibers added is 0.05% to 0.15% of the total mass of the castable.

7. The in-situ reinforced lightweight porous corundum refractory castable according to claim 6, characterized in that: The alumina fibers undergo surface modification, specifically through the following steps: Step S1: Place the alumina fiber in a mixed acid solution and sonicate for 10 min to 15 min, then treat it in a water bath at 60℃ to 65℃ for 1 h to 1.5 h, wash it with deionized water, and dry it to obtain the pretreated fiber. Step S2: Mix ammonium molybdate tetrahydrate, aluminum chloride hexahydrate and silica sol, dissolve in deionized water to obtain impregnation solution; The pretreated fibers are placed in an impregnation solution and vacuum impregnated for 30 to 40 minutes. They are then freeze-dried at -80°C for 12 to 16 hours. The temperature is then increased to 800°C to 820°C at a rate of 5°C to 6°C per minute, followed by a further increase to 900°C to 920°C at a rate of 1°C to 2°C per minute. The temperature is maintained for 1 to 2 hours, and the fibers are then allowed to cool naturally to obtain surface-modified alumina fibers.

8. The method for preparing an in-situ reinforced lightweight porous corundum refractory castable according to claim 7, characterized in that: In step S1, the mixed acid solution is a mixture of hydrochloric acid and sulfuric acid in a volume ratio of 1:1; in step S2, the mass ratio of ammonium molybdate tetrahydrate, aluminum chloride hexahydrate, and silica sol is (5~7) (120~125): (8~10); the pressure during vacuum impregnation is 0.01MPa~0.04MPa.

9. A method for preparing an in-situ reinforced lightweight porous corundum refractory castable according to any one of claims 1 to 8, characterized in that: The specific steps are as follows: Weigh the raw material powder according to the ratio, stir for 3 to 5 minutes, add water, continue stirring for 3 to 5 minutes, finally pour the mixture into the mold and vibrate to form it, cure at room temperature for 12 to 36 hours, and then demold to obtain the corundum refractory castable.

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