High-strength refractory material as well as preparation method and local rapid maintenance and use method thereof

Abstract

The invention belongs to the technical field of refractory castable, and particularly relates to a high-strength refractory material as well as a preparation method and a local rapid maintenance and use method thereof. The high-strength refractory material is prepared from hydrated alumina, nanometer silica sol dry powder and potassium aluminum fluosilicate, the potassium aluminum fluosilicate is hydrolyzed after water is added to generate HF and active SiO2, the HF catalyzes dehydration of the hydrated alumina, the active SiO2 initiates polycondensation of nanometer silicon and the dehydrated hydrated alumina, an Al-O-Si three-dimensional gel network is formed, meanwhile, an AlF3 curing phase is generated in situ, and the high-strength refractory material is prepared. Wherein within 2 h after water adding construction, a gel shell composed of the Al-O-Si three-dimensional gel network is formed on the surface of the refractory material maintenance area, the water locking and anti-cracking functions are achieved, and the AlF3 curing phase is a high-melting-point, non-volatile and chemically inert solid phase formed after HF is safely captured by hydrated alumina.

Description

Technical Field

[0001] This application belongs to the field of refractory castable technology, and in particular relates to a high-strength refractory material, its preparation method and local rapid repair method. Background Technology

[0002] Commonly used aluminum smelting equipment mainly includes: medium-frequency induction furnaces, crucible furnaces, dry-bed continuous melting furnaces, and reverberatory furnaces. Taking a reverberatory furnace as an example, its furnace door and aluminum outlet are vulnerable parts due to the following reasons, requiring frequent repair and maintenance: First, this location is frequently subjected to alternating hot and cold shocks, as well as mechanical impacts. Secondly, molten aluminum and various additives will cause significant corrosion and penetration at this location.

[0003] Therefore, compared with monolithically castable refractory castables that serve for a long time, the castables used in the above-mentioned filling and maintenance operations need to take into account both the characteristics of fast drying and high strength, especially the fast drying performance and the early compressive strength after filling and maintenance.

[0004] For example, invention patent application CN117229042A, published on December 15, 2023, discloses a high-strength refractory material for localized rapid repair, its preparation method, and its application method. The raw material composition of this high-strength refractory material mainly includes: high-alumina bauxite, corundum, α-Al₂O₃ micro powder, hardener, sintering agent, explosion-proof agent, and aluminum dihydrogen phosphate powder.

[0005] The high-strength refractory material in this invention patent application has the following advantages: excellent bonding performance with the substrate, while also possessing excellent strength and non-wetting properties of molten aluminum.

[0006] However, when this high-strength refractory material is used in actual reverberatory furnace filling and maintenance operations, it still suffers from relatively low early compressive strength, specifically manifested as follows: The 6-hour and 24-hour room temperature compressive strength of its phosphate system were not disclosed. However, it is common knowledge that, for example, the 6-hour strength mentioned above is generally only <5MPa, or even uncured. Therefore, the early compressive strength is relatively insufficient. The "6-8 hours" mentioned in its embodiments only refers to allowing demolding, not allowing it to be put into use. Summary of the Invention

[0007] This application provides a high-strength refractory material, the technical problem to be solved by which the refractory material has a relatively high early room temperature compressive strength during the filling and repair operation, so as to ensure that the repaired equipment can be put into use in a short time.

[0008] In addition, this application also provides a method for preparing the above-mentioned high-strength refractory material and a method for local rapid repair and use of the above-mentioned high-strength refractory material.

[0009] The technical solution adopted by this application to solve the above problems is: a high-strength refractory material, characterized in that the raw material composition includes: hydrated alumina, nano-silica sol dry powder, and potassium aluminum fluorosilicate. In this process, potassium aluminum fluorosilicate hydrolyzes upon the addition of water to produce HF and active SiO2. HF catalyzes the dehydration of hydrated alumina, while active SiO2 initiates the condensation polymerization of nano-silicon with the dehydrated hydrated alumina, forming an Al-O-Si three-dimensional gel network. Simultaneously, an AlF3 solidified phase is generated in situ. Within 2 hours after water addition, a gel shell composed of the Al-O-Si three-dimensional gel network forms on the surface of the refractory material repair area, which plays a role in locking in water and preventing cracking.

[0010] In this application, the AlF3 solidified phase is a high-melting-point, non-volatile, and chemically inert solid phase formed after hydrated alumina safely captures HF.

[0011] A further preferred technical solution is that the hydrated alumina is in the form of nanosheets with a specific surface area ≥250 m². 2 / g; In the nano-silica sol dry powder, the weight ratio of SiO2 is 35-40%, and the rest is inactive components such as carrier, dispersant, anti-caking agent and residual moisture, and the particle size of SiO2 is 15-25nm; The purity of potassium aluminum fluorosilicate is ≥98%.

[0012] A further preferred technical solution is that the raw material composition includes the following components: high-alumina bauxite, white corundum fine powder, α-Al2O3 micro powder, hydrated alumina, nano-silica sol dry powder, and potassium aluminum fluorosilicate.

[0013] A further preferred technical solution is that: the Al2O3 content of the high-alumina bauxite is ≥85%, and the weight percentage of materials with a particle size of 2-4mm in the high-alumina bauxite is ≥75%; the D90 of the white corundum fine powder is ≤45μm; and the D50 of the α-Al2O3 micro powder is 0.4-0.5μm.

[0014] A further preferred technical solution is that the raw material composition also includes the following components: B4C micro powder, nano ZrO2, chopped alumina ceramic fibers, and polycarboxylate superplasticizer. During the medium-temperature baking stage, B4C micropowder oxidizes to generate gaseous B2O3 and CO, forming exhaust channels. These channels are guided and deflected by short-cut alumina ceramic fibers, forming a permeable network that provides anti-cracking protection. After the medium-temperature baking stage, the remaining B2O3 reverts to a solid state. Among them, ZrO2 nano4+ The Al-O-Si three-dimensional gel network is doped to promote its growth. When the refractory material is put into use in the repair area, the solid B2O3 transforms into a liquid phase and reacts with Al2O3 to form a boroaluminate glass phase. At the same time, ZrO2 undergoes a crystal structure transformation from a tetragonal phase to a monoclinic phase.

[0015] In this application, the aforementioned function of promoting the growth of three-dimensional gel networks enhances the strength of the refractory material repair area and allows the refractory material repair area to be maintained without external curing.

[0016] In this application, both the boroaluminate glass phase and the monoclinic ZrO2 phase can densify the repair area of ​​the refractory material, inhibit crack propagation, and make the repair area of ​​the refractory material high-strength and toughened.

[0017] A further preferred technical solution is that: the B4C micro powder has a D50 of 0.8-1.0 μm and a free C content of ≤1 wt%; the nano ZrO2 is 3Y-ZrO2 with a D50 of 30-40 μm; the alumina chopped ceramic fiber has an Al2O3 content of ≥95%, a diameter of 4-5 μm, and a length of 3-4 mm; and the polycarboxylate superplasticizer has a solid content of 40%.

[0018] A further preferred technical solution is that the raw material composition includes the following components by weight: High alumina: 60-65%; White fused alumina fine powder: 12-14%; α-Al₂O₃ micro powder: 14.0-18.0%; Hydrated alumina: 5.0-7.0%; Nano-silica sol dry powder: 2.0-4.0%; Potassium aluminum fluorosilicate: 1.0-3.0%; B4C micro powder: 0.5-1.0%; Nano ZrO2: 1.0-2.0%; Alumina chopped ceramic fibers: 0.2-1.0%; Polycarboxylate superplasticizer: 0.2-0.5%.

[0019] A method for preparing the high-strength refractory material includes the following steps in sequence: S1. In a mixer, dry mix high-alumina bauxite, white corundum fine powder, α-Al2O3 micro powder, B4C micro powder and alumina short-cut ceramic fibers for 5-10 minutes, and pour out to obtain material A. S2. Dry the hydrated alumina, nano ZrO2 and nano silica sol dry powder under vacuum at 60℃ for 2-3 hours to obtain the dried material. S3. In a mixer, the dried material is mixed with potassium aluminum fluorosilicate and polycarboxylate superplasticizer for 8-10 minutes under a nitrogen protective atmosphere, and then left in the mixer as material B. S4. Add material A to material B, mix for 6-15 minutes, pour out and then fill with nitrogen and seal in packaging to obtain the final high-strength refractory material product.

[0020] A method for localized rapid repair of the aforementioned high-strength refractory material includes the following steps in sequence. T1. Clean the parts of the aluminum smelting equipment that need repair; T2. Mix the high-strength refractory material with deionized water and stir for 3-4 minutes, with a water-to-material ratio of 5.5-6.5 wt%, to obtain a wet material; T3. Apply the wet material to the area to be repaired by smearing or pouring, and then cover it with a microporous breathable membrane. T4. After natural curing for 6 hours, remove the microporous breathable membrane and enter the medium-temperature baking stage. The total baking time is ≤10 hours, which completes the entire local rapid repair operation and the device can then be put into use.

[0021] A further preferred technical solution is that, in T4, the medium-temperature baking stage first raises the temperature from room temperature to 200°C, and then to 600°C, with the heating rate of the first stage of baking ≤50°C / h and the heating rate of the second stage of baking ≤80°C / h.

[0022] In this application, the molecular formulas or abbreviations of the above components are as follows: hydrated alumina: AlOOH, nano silica sol dry powder: nano SiO2, potassium aluminum fluorosilicate: KAlF4·SiF6.

[0023] In this application, KAlF4·SiF6 has at least the following three functions.

[0024] First, hydrolysis releases HF, which can catalyze the dehydration of AlOOH. Otherwise, AlOOH would be difficult to undergo condensation reaction and it would be impossible to form the above-mentioned Al-O-Si three-dimensional gel network. Second, after hydrolysis, active SiO2 is formed, which initiates and participates in the condensation polymerization of nano-SiO2 and dehydrated AlOOH. Third, Al is released after hydrolysis. 3+ Similar to the aforementioned active SiO2, it can also rapidly guide the formation of Al-O-Si three-dimensional gel networks.

[0025] In this application, B4C micro powder has at least the following two functions.

[0026] First, during the medium-temperature baking stage, B4C reacts with O2 to generate B2O3(g) and CO. The latter two are discharged to form an exhaust channel, which plays a basic role in preventing bursting and is a prerequisite for the subsequent, fully connected breathable network. Secondly, during the application phase of the refractory repair area, the residual B2O3 transforms into a liquid phase and reacts with Al2O3 to form a borosilicate glass phase, which rapidly densifies the repair area and inhibits crack propagation. The final effect is that the repair area has the advantage of high strength.

[0027] In this application, nano ZrO2 also has at least the following two functions.

[0028] First, during the curing phase in the refractory material repair area, Zr 4+ Doping the Al-O-Si three-dimensional gel network promotes its growth, enhances the strength of the refractory material repair area, and allows the refractory material repair area to be cured without external maintenance. Secondly, during the aforementioned commissioning phase, ZrO2 undergoes a crystal structure transformation from the tetragonal phase to the monoclinic phase, which can give the repair area of ​​the refractory material the advantage of toughening.

[0029] In addition, it should be noted that the application of fluorinated compounds in refractory materials will inevitably raise concerns about environmental protection, safety and industrial acceptance. However, the form of fluorine and the release behavior of fluorine in KAlF4·SiF6 used in this application are fundamentally different from those of traditional free fluorides (such as CaF2, Na3AlF6, etc.), as detailed below.

[0030] First, KAlF4·SiF6 is a complex salt fluoride, in which fluorine is tightly bound to [AlF4] by covalent bonds. - and [SiF6] 2- Anions are extremely difficult to dissociate at room temperature; Secondly, unlike volatile and highly toxic HF gas or soluble sodium fluoride, KAlF4·SiF6 has low water solubility (<2 g / 100g water) and is stable in a dry state. Third, the release of fluoride is "controlled, trace, and instantaneous," and only occurs through controlled hydrolysis after the addition of water and stirring. Fourth, in an alkaline / Al-rich environment, HF is rapidly captured by the AlF3 curing phase. The resulting AlF3 has a high melting point (1290℃), is non-volatile, and insoluble in water, and is eventually cured in the matrix.

[0031] The actual test results showed that the concentration of HF in the air in the construction area was <0.1 ppm, which is far below the OSHA limit of 3 ppm.

[0032] The beneficial effects of this application include at least the following four points.

[0033] First, when this high-strength refractory material is used for filling and maintenance work in equipment such as reverberatory furnaces, it has relatively high early room temperature compressive strength, specifically: 6h strength ≥15MPa, 24h strength ≥33MPa. Its fast-drying and high-strength characteristics make it very suitable for maintenance work.

[0034] Secondly, the repair area formed by this high-strength refractory material has a surface drying time of ≤30 minutes, can be baked after 6 hours, and can be put into use within 10 hours of baking, making it suitable for local rapid repair operations.

[0035] Third, after being put into use, the above-mentioned maintenance area supports rapid heating operation at 100℃ / min without cracking.

[0036] Fourth, the compressive strength of the above-mentioned repair area after burning at 1000℃ (1000℃×3h) is ≥52MPa, which corresponds to the actual working conditions of equipment such as reverberatory furnaces. This indicates that the high-strength refractory material also has relatively high strength in later use. Attached Figure Description

[0037] Figure 1 The results are the average test results of the samples in the four embodiments and five comparative examples of this application.

[0038] Figure 2 This is a photograph of a partial repair method for the high-strength refractory material in Embodiment 1 of this application.

[0039] Figure 3 for Figure 2 Enlarged image. Detailed Implementation

[0040] The following description is merely a preferred embodiment of this application and is not intended to limit the scope of this application.

[0041] Example 1

[0042] A high-strength refractory material comprises the following components by weight: 62% high-alumina bauxite, 12% white corundum fine powder, 14.5% α-Al2O3 micro powder, 5.5% hydrated alumina, 2.5% nano-silica sol dry powder, 1.0% potassium aluminum fluorosilicate, 0.6% B4C micro powder, 1.2% nano ZrO2, 0.4% alumina chopped ceramic fibers, and 0.3% polycarboxylate superplasticizer, totaling 100%, with a total batch size of 50 kg.

[0043] Among them, the Al2O3 content of high-alumina bauxite is ≥85%, and the weight proportion of materials with a particle size of 2-4mm in high-alumina bauxite is ≥75%; the D90 of white corundum fine powder is ≤45μm; and the D50 of α-Al2O3 micro powder is 0.4μm.

[0044] Among them, hydrated alumina is in the form of nanosheets with a specific surface area ≥250 m². 2 / g; In the nano-silica sol dry powder, the weight ratio of SiO2 is 35%, and the particle size of SiO2 is 15-25nm; The purity of potassium aluminum fluorosilicate is ≥98%.

[0045] Among them, the B4C micro powder has a D50 of 0.8 μm and a free C content of ≤1 wt%; the nano ZrO2 is 3Y-ZrO2 with a D50 of 40 μm; the alumina chopped ceramic fiber has an Al2O3 content of ≥95%, a diameter of 4.0-4.5 μm, and a length of 3-4 mm; and the polycarboxylate superplasticizer has a solid content of 40%.

[0046] The preparation method of the above-mentioned high-strength refractory material includes the following steps in sequence.

[0047] S1. In a mixer, dry mix high-alumina bauxite, white corundum fine powder, α-Al2O3 micro powder, B4C micro powder and alumina short-cut ceramic fibers for 5 min, and pour out to obtain material A; S2. The hydrated alumina, nano ZrO2 and nano silica sol dry powder are dried under vacuum at 60°C for 2 hours to obtain the dried material. S3. In a mixer, the dried material is mixed with potassium aluminum fluorosilicate and polycarboxylate superplasticizer for 8 minutes under a nitrogen protective atmosphere, and then left in the mixer as material B. S4. Add material A to material B, mix for 6 minutes, pour out and then fill with nitrogen and seal in packaging to obtain the final high-strength refractory material product.

[0048] The above-mentioned method for localized rapid repair of high-strength refractory materials includes the following steps in sequence.

[0049] T1. Clean the parts of the aluminum smelting equipment that need repair; T2. Mix the high-strength refractory material with deionized water and stir for 4 minutes. The water-to-material ratio is 5.5 wt%, to obtain a wet material. T3. Apply the wet material to the area to be repaired by wiping, and then cover it with a microporous breathable membrane; T4. After natural curing for 6 hours, remove the microporous breathable membrane and enter the medium-temperature baking stage. The total baking time is ≤9.5 hours, which completes the entire local rapid repair operation and the device can then be put into use.

[0050] In T4, the medium-temperature baking stage involves first raising the temperature from room temperature to 200°C, and then to 600°C. The heating rate of the first stage of baking is ≤50°C / h, and the heating rate of the second stage of baking is ≤80°C / h.

[0051] Example 2

[0052] The high-strength refractory material, its preparation method, and its local rapid repair and application method in this embodiment differ from those in Embodiment 1 in only one aspect.

[0053] The raw material composition, without exceeding the above range, is set as follows: 61% high-alumina bauxite, 12% white corundum fine powder, 14% α-Al2O3 micro powder, 5.5% hydrated alumina, 3% nano silica sol dry powder, 2.0% potassium aluminum fluorosilicate, 0.6% B4C micro powder, 1.2% nano ZrO2, 0.5% alumina chopped ceramic fiber, and 0.2% polycarboxylate superplasticizer.

[0054] Example 3

[0055] The high-strength refractory material, its preparation method, and its local rapid repair and application method in this embodiment differ from those in Embodiment 1 in only one aspect.

[0056] B4C micro powder, nano ZrO2, alumina chopped ceramic fibers and polycarboxylate superplasticizer are mixed in the above proportions and then removed from the mixture.

[0057] Example 4

[0058] The high-strength refractory material, its preparation method, and its local rapid repair and application method in this embodiment differ from those in Embodiment 1 in only one aspect.

[0059] After mixing B4C micro powder and nano ZrO2 in the above proportions, remove the powder and discard it.

[0060] Comparative Example 1 The high-strength refractory material, its preparation method, and its local rapid repair and application method in this comparative example differ from those in Example 1 in only one aspect, as follows.

[0061] Hydrated alumina, nano silica sol dry powder, potassium aluminum fluorosilicate, B4C micro powder, nano ZrO2, alumina chopped ceramic fibers and polycarboxylate superplasticizer are mixed in the above proportions and then removed and replaced with calcium aluminate cement with appropriate addition amounts.

[0062] Comparative Example 2 The high-strength refractory material, its preparation method, and its local rapid repair and application method in this comparative example differ from those in Example 1 in only the following two aspects.

[0063] First, after mixing B4C micro powder, nano ZrO2, alumina chopped ceramic fibers and polycarboxylate superplasticizer in the above proportions, remove all of them and do not use them.

[0064] Secondly, the nano-silica sol powder and potassium aluminum fluorosilicate were also mixed in the above proportions and then removed and not used.

[0065] Comparative Example 3 The high-strength refractory material, its preparation method, and its local rapid repair and application method in this comparative example differ from those in Example 1 in only the following two aspects.

[0066] First, after mixing B4C micro powder, nano ZrO2, alumina chopped ceramic fibers and polycarboxylate superplasticizer in the above proportions, remove all of them and do not use them.

[0067] Second, after mixing potassium aluminum fluorosilicate according to the above proportions, all of it should be removed and not used.

[0068] Comparative Example 4 The high-strength refractory material, its preparation method, and its local rapid repair and application method in this comparative example differ from those in Example 1 in only the following two aspects.

[0069] First, after mixing B4C micro powder, nano ZrO2, alumina chopped ceramic fibers and polycarboxylate superplasticizer in the above proportions, remove all of them and do not use them.

[0070] Second, the nano-silica sol dry powder should be taken out and not used after being prepared according to the above proportions.

[0071] Comparative Example 5 The high-strength refractory material, its preparation method, and its local rapid repair and application method in this comparative example differ from those in Example 1 in only one aspect, as follows.

[0072] Hydrated alumina, nano silica sol powder, and potassium aluminum fluorosilicate are mixed in the above proportions and then discarded. However, an appropriate amount of calcium aluminate cement is added.

[0073] Performance testing Attached Figure 1 The five test items are: 6-hour room temperature compressive strength (MPa), 24-hour room temperature compressive strength (MPa), 1000℃ post-burning compressive strength (1000℃×3h, MPa), surface drying time (min), and bursting at 100℃ / min. Sampling tests were conducted on the above four examples and five comparative examples. Each data point for each example / comparative example was tested at least five times, and the average value was recorded in the appendix. Figure 1 In the table.

[0074] The specific reference standards for the above tests are as follows.

[0075] 6-hour room temperature compressive strength: GB / T 30873-2014 "Test Method for Thermal Shock Resistance of Refractory Materials" (Note: Strength test is referenced from GB / T 5072) 24-hour room temperature compressive strength: GB / T 5072-2008 "Test Method for Room Temperature Compressive Strength of Refractory Materials" Compressive strength after firing at 1000℃: GB / T 5988-2022 "Test Method for Permanent Linear Change of Refractory Materials under Heating" (with accompanying heat treatment) + GB / T 5072-2008 Test Result Analysis First, the collaborative system significantly enhances early-stage strength and rapid drying. Compared with Comparative Examples 2-4, Example 1 showed a 2.4-2.5 times increase in room temperature compressive strength after 6 hours and a 50-65 minute reduction in surface drying time. The key driver was the rapid formation of an Al-O-Si three-dimensional gel network by potassium aluminum fluorosilicate catalyzing AlOOH and nano-silica sol dry powder.

[0076] The strength of Comparative Example 3 (with nano-silica sol dry powder and no potassium aluminum silicate) is higher than that of Comparative Example 4 (without nano-silica sol dry powder and with potassium aluminum silicate), but neither is as good as Examples 1 and 2. Therefore, this shows that nano-silica sol dry powder provides the network framework and potassium aluminum silicate provides the catalysis, and neither can be missing.

[0077] Secondly, B4C micro powder and alumina chopped ceramic fibers are the core combination for anti-cracking. As can be seen from Example 4, alumina chopped ceramic fibers can alleviate but cannot completely replace the pore-forming function of B4C micro powder.

[0078] Third, ZrO2 makes a significant contribution to high-temperature strength. The phase transformation toughening of ZrO2 is activated above 800℃, effectively inhibiting crack propagation.

[0079] The embodiments of this application have been described in detail above with reference to the accompanying drawings. However, this application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various modifications can be made without departing from the spirit of this application. These are non-inventive modifications and are protected by patent law as long as they are within the scope of the claims of this application.

Claims

1. A high-strength refractory material, characterized in that... The raw material composition includes: hydrated alumina, nano-silica sol powder, and potassium aluminum fluorosilicate. In this process, potassium aluminum fluorosilicate hydrolyzes upon the addition of water to produce HF and active SiO2. HF catalyzes the dehydration of hydrated alumina, while active SiO2 initiates the condensation polymerization of nano-silicon with the dehydrated hydrated alumina, forming an Al-O-Si three-dimensional gel network. Simultaneously, an AlF3 solidified phase is generated in situ. Within 2 hours after water addition, a gel shell composed of the Al-O-Si three-dimensional gel network forms on the surface of the refractory material repair area, which plays a role in locking in water and preventing cracking.

2. The high-strength refractory material according to claim 1, characterized in that: The hydrated alumina is in the form of nanosheets with a specific surface area ≥250 m². 2 / g; the weight percentage of SiO2 in the nano silica sol dry powder is 35-40%, and the particle size of SiO2 is 15-25nm; the purity of the potassium aluminum fluorosilicate is ≥98%.

3. The high-strength refractory material according to claim 1, characterized in that... The raw material composition includes the following components: High-alumina bauxite, white corundum fine powder, α-Al2O3 micro powder, hydrated alumina, nano-silica sol dry powder, and potassium aluminum fluorosilicate.

4. The high-strength refractory material according to claim 3, characterized in that: The high-alumina bauxite has an Al2O3 content of ≥85%, and the weight percentage of materials with a particle size of 2-4mm in the high-alumina bauxite is ≥75%; the D90 of the white corundum fine powder is ≤45μm; and the D50 of the α-Al2O3 micro powder is 0.4-0.5μm.

5. A high-strength refractory material according to claim 3, characterized in that... The raw material composition also includes the following components: B4C micro powder, nano ZrO2, chopped alumina ceramic fibers, and polycarboxylate superplasticizer. During the medium-temperature baking stage, B4C micropowder oxidizes to generate gaseous B2O3 and CO, forming exhaust channels. These channels are guided and deflected by short-cut alumina ceramic fibers, forming a permeable network that provides anti-cracking protection. After the medium-temperature baking stage, the remaining B2O3 reverts to a solid state. Among them, ZrO2 nano 4+ The Al-O-Si three-dimensional gel network is doped to promote its growth. When the refractory material is put into use in the repair area, the solid B2O3 transforms into a liquid phase and reacts with Al2O3 to form a boroaluminate glass phase. At the same time, ZrO2 undergoes a crystal structure transformation from a tetragonal phase to a monoclinic phase.

6. The high-strength refractory material according to claim 5, characterized in that: The B4C micro powder has a D50 of 0.8-1.0 μm and a free C content of ≤1 wt%; the nano ZrO2 is 3Y-ZrO2 with a D50 of 30-40 μm; the alumina chopped ceramic fibers have an Al2O3 content of ≥95%, a diameter of 4-5 μm, and a length of 3-4 mm; the polycarboxylate superplasticizer has a solid content of 40%.

7. A high-strength refractory material according to claim 5, characterized in that... The raw material composition includes the following components by weight: High alumina: 60-65%; White fused alumina fine powder: 12-14%; α-Al₂O₃ micro powder: 14.0-18.0%; Hydrated alumina: 5.0-7.0%; Nano-silica sol dry powder: 2.0-4.0%; Potassium aluminum fluorosilicate: 1.0-3.0%; B4C micro powder: 0.5-1.0%; Nano ZrO2: 1.0-2.0%; Alumina chopped ceramic fibers: 0.2-1.0%; Polycarboxylate superplasticizer: 0.2-0.5%.

8. A method for preparing the high-strength refractory material as described in claim 7, characterized in that: The steps are as follows: S1. In a mixer, dry mix high-alumina bauxite, white corundum fine powder, α-Al2O3 micro powder, B4C micro powder and alumina short-cut ceramic fibers for 5-10 minutes, and pour out to obtain material A; S2. Dry the hydrated alumina, nano ZrO2 and nano silica sol dry powder under vacuum at 60℃ for 2-3 hours to obtain the dried material. S3. In a mixer, the dried material is mixed with potassium aluminum fluorosilicate and polycarboxylate superplasticizer for 8-10 minutes under a nitrogen protective atmosphere, and then left in the mixer as material B. S4. Add material A to material B, mix for 6-15 minutes, pour out and then fill with nitrogen and seal in packaging to obtain the final high-strength refractory material product.

9. A method for localized rapid repair of high-strength refractory material as described in any one of claims 1-7, characterized in that: The steps are as follows: T1. Clean the parts of the aluminum smelting equipment that need repair; T2. Mix the high-strength refractory material with deionized water and stir for 3-4 minutes, with a water-to-material ratio of 5.5-6.5 wt%, to obtain a wet material; T3. Apply the wet material to the area to be repaired by smearing or pouring, and then cover it with a microporous breathable membrane. T4. After natural curing for 6 hours, remove the microporous breathable membrane and enter the medium-temperature baking stage. The total baking time is ≤10 hours, which completes the entire local rapid repair operation and the device can then be put into use.

10. A method for localized rapid repair of the high-strength refractory material according to claim 9, characterized in that: In T4, the medium-temperature baking stage involves first raising the temperature from room temperature to 200°C, and then to 600°C. The heating rate of the first stage of baking is ≤50°C / h, and the heating rate of the second stage of baking is ≤80°C / h.

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