High thermal shock resistant monolithic refractory and method for producing the same

Abstract

The application belongs to the technical field of refractory materials, and particularly relates to high thermal shock resistance amorphous refractory material and a preparation method thereof. The high thermal shock resistance amorphous refractory material comprises corundum, magnesium aluminate spinel, a binder, nano micropowder, quartz glass powder, polyaluminum phosphate and sodium tripolyphosphate. The high thermal shock resistance amorphous refractory material is prepared by using high-alumina cement, aluminum sol and silicon micropowder to jointly form the binder, so as to reduce the overall expansion rate of the material, improve the interface bonding strength and cracking resistance in the thermal shock process; the aluminum sol with low acid and high solid content is prepared by using a hydrothermal method, so as to reduce the thermal expansion difference, buffer thermal shock, and further improve the thermal shock resistance of the amorphous refractory material; the nano micropowder is composed of nano carbon black, nano cerium oxide and nano aluminum oxide, and through the synergistic mechanism of thermal conduction regulation, grain refinement and interface strengthening, the thermal shock resistance of the amorphous refractory material is significantly improved.

Description

Technical Field

[0001] This invention belongs to the field of refractory materials technology, specifically relating to a highly thermally shock resistant monomorphic refractory material and its preparation method. Background Technology

[0002] As an important branch of the refractory materials field, unshaped refractories have been applied in high-temperature industrial fields such as steel, metallurgy, building materials, chemical industry, and energy due to their significant advantages such as no need for pre-firing, convenient construction, strong adaptability, high resource utilization and controllable cost. They have become the core protective material for the lining of high-temperature kilns and thermal equipment. Their performance directly determines the service life, operational stability and production safety of thermal equipment, and plays an irreplaceable role in ensuring continuous and efficient production in high-temperature industries and reducing energy consumption and operation and maintenance costs.

[0003] In actual production processes at high-temperature industries, thermal equipment often faces extremely harsh temperature conditions. Frequent heating and cooling operations, as well as drastic fluctuations in local temperature, subject the refractory lining to continuous cyclical thermal stress. This repeated accumulation and release of thermal stress easily induces microcracks within the material. As these cracks expand and penetrate, they eventually lead to spalling, cracking, or even overall failure—the so-called "thermal shock damage." Therefore, thermal shock resistance has become a key indicator for evaluating the core performance of monolithic refractories. Developing monolithic refractories with excellent thermal shock resistance is one of the core research directions in the current refractory materials field.

[0004] Currently, conventional methods used in the industry to improve the thermal shock resistance of monolithic refractories mainly include optimizing particle size distribution to improve material density and pore structure, and introducing mineral components with low expansion coefficients to reduce thermal stress. However, optimizing particle size distribution can easily sacrifice the material's room temperature strength and high temperature compressive strength, leading to structural deformation when subjected to high-temperature loads; introducing mineral components with low expansion coefficients significantly increases the material preparation cost, which is not conducive to large-scale promotion and application.

[0005] Chinese patent application CN106316433A discloses an unshaped refractory material comprising 40%-60% forsterite, 20%-30% yttrium oxide powder, 10%-20% zirconia powder, 5%-9% binder, and 1%-5% plasticizer. Based on 100% by weight of forsterite, the particle size distribution and corresponding mass ratios are: 8-5mm 20%-30%, 5-3mm 50%-65%, 3-1mm 10%-15%, and less than 1mm ≤5%. However, this formula has a high proportion of coarse particles and a low proportion of fine and micro powders. The coarse particle gradation makes it difficult for the material to form a dense packing structure during construction and vibration, and it is easy to leave a large number of through pores. This will not only reduce the material's room temperature mechanical strength and high temperature compressive strength, but may also exacerbate thermal stress concentration due to uneven pore distribution, affecting the stability of thermal shock resistance. At the same time, after the high proportion of magnesium olivine is compounded with yttrium oxide and zirconium oxide components, the thermal expansion coefficients of each component are significantly different. During high-temperature service, interfacial microcracks are easily generated due to thermal expansion mismatch, affecting service life. Summary of the Invention

[0006] In order to solve the technical problem of poor thermal shock resistance in the prior art, the purpose of this invention is to provide a high thermal shock resistant unshaped refractory material and its preparation method.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] A highly thermally shock resistant monolithic refractory material, comprising the following components in parts by weight:

[0009] 70-80 parts corundum, 50-60 parts magnesium aluminum spinel, 20-35 parts binder, 12-20 parts nano-powder, 10-15 parts quartz glass powder, 3-8 parts polyaluminum phosphate, and 1-3 parts sodium tripolyphosphate.

[0010] The binder is composed of high-alumina cement, alumina sol and silica powder in a mass ratio of (10-15):(7-11):(3-6).

[0011] The above technical solution employs high-alumina cement, alumina sol, and silica fume as a binder. High-alumina cement, as an inorganic cementitious material, hydrates to produce hydration products such as monocalcium aluminate and dicalcium aluminate, rapidly forming a three-dimensional network structure. This imparts strength to the material at room temperature and medium-low temperatures. At high temperatures, the hydration products dehydrate and transform into a corundum phase, forming a strong ceramic bond with the refractory aggregate, enhancing the stability of the matrix structure. The corundum phase of high-alumina cement has a low coefficient of thermal expansion, reducing the overall expansion rate of the material. Alumina sol exhibits high activity; at room temperature, it forms a dense alumina gel film through water evaporation, filling the micropores between the hydration products of high-alumina cement. At high temperatures, it transforms into γ-Al₂O₃, further reacting with the alumina in the high-alumina cement. The gel film forms a continuous ceramic bonding interface, which improves the interfacial wettability between the binder and refractory aggregate, reduces interfacial porosity and cracks, and reduces the concentration of thermal stress at the interface. Silica powder has a high specific surface area and high reactivity. At high temperatures, it can react with calcium oxide and alumina in high-alumina cement to generate low-melting-point calcium feldspar or magnesium aluminum spinel phases, which fill the micron-sized pores in the matrix. The calcium feldspar and magnesium aluminum spinel phases have low coefficients of thermal expansion, further reducing the overall thermal expansion difference of the material and reducing thermal stress. The silica powder particles can also increase the matrix density through the filling effect. The needle-like crystal structure of the magnesium aluminum spinel phase can form "interlocking support" in the matrix, improving the fracture toughness of the material and enhancing the cracking resistance during thermal shock.

[0012] In addition, quartz glass powder forms a low-viscosity glass phase at high temperatures, which can fill micropores, improve density, and alleviate thermal stress; polyaluminum phosphate decomposes at high temperatures, releasing phosphorus pentoxide, and reacts with alumina and other substances in the monolithic refractories to form an aluminum phosphate ceramic phase, which fills the pores between aggregates, forming a continuous ceramic bonding interface and improving the high-temperature compressive strength of the material. The decomposition process forms uniform micropores in the monolithic refractories, which can buffer thermal stress and inhibit crack propagation through the elastic deformation of the micropores; sodium tripolyphosphate can optimize particle dispersion and improve matrix density.

[0013] Furthermore, the binder is composed of high-alumina cement, alumina sol, and silica fume in a mass ratio of (12-14):(8-10):(5-6).

[0014] Furthermore, the preparation method of the aluminum sol is as follows: aluminum isopropoxide is added to a reaction vessel, deionized water is added dropwise while stirring, the temperature in the reaction vessel is controlled to be <50℃ during the dropwise addition, stirring is continued for 30-50 minutes after the dropwise addition is completed, the temperature is raised to 85-90℃, and the temperature is maintained for 2-3 hours. Isopropanol is recovered by distillation, cooled, concentrated nitric acid is added, stirred evenly, the temperature is raised to 220-230℃, and the reaction is maintained for 20-22 hours. After cooling, the mixture is filtered to obtain aluminum sol.

[0015] Through the above technical solution, a low-acid, high-solids-content alumina sol is prepared using a hydrothermal method. The low acid content avoids the erosion problem of refractory aggregates caused by excessive acid content in the alumina sol. Aluminum isopropoxide is used to recover isopropanol through distillation, reducing the impurity content in the alumina sol and minimizing the need for water addition, thus lowering the porosity of the refractory material. A high-temperature hydrothermal reaction for 20-22 hours improves the crystallinity of the sol particles, resulting in a uniform grain size distribution. During the use of monolithic refractories, the alumina sol can rapidly transform into γ-Al₂O₃, and the nano-sized particles, after converting to alumina, can fill the micropores in the refractory matrix. Simultaneously, a slight solid-phase reaction occurs with the aggregate surface, forming a dense bonding layer, increasing the material density, reducing thermal expansion differences, buffering thermal shock, and thus improving the thermal shock resistance of the monolithic refractories.

[0016] Furthermore, the deionized water used in the preparation method of aluminum sol is deionized water that has been boiled and cooled to 40-45℃; the dropping rate of the deionized water is 10-15 mL / min.

[0017] The above technical solution effectively removes dissolved oxygen from deionized water by boiling and cooling it before use, reducing the oxidative aggregation of colloidal particles. Controlling the dripping speed of deionized water can prevent localized rapid hydrolysis and precipitation caused by adding deionized water too quickly.

[0018] Furthermore, in the preparation method of aluminum sol, the mass ratio of aluminum isopropoxide to deionized water is 1:(1.5-1.7); the mass ratio of aluminum isopropoxide to concentrated nitric acid is (50-60):1; and the mass percentage of concentrated nitric acid is 65%-70%.

[0019] Furthermore, the nanopowder is composed of nano carbon black, nano cerium oxide and nano aluminum oxide in a mass ratio of (5-9):(7-12):(15-20).

[0020] The above technical solution utilizes nano-carbon black, nano-cerium oxide, and nano-alumina to form nanoparticles. Through a synergistic mechanism of thermal conductivity regulation, grain refinement, and interface strengthening, the thermal shock resistance of monolithic refractories is significantly improved. Nano-carbon black can construct a three-dimensional thermally conductive network within the monolithic refractories, accelerating the dispersion of thermal stress. Nano-cerium oxide inhibits abnormal grain growth through grain boundary pinning. Nano-alumina acts as an active sintering aid, forming a dense solid solution with the matrix, enhancing interfacial bonding strength, and reducing interfacial delamination caused by thermal shock cycling.

[0021] Furthermore, the nanopowder is composed of nano carbon black, nano cerium oxide and nano aluminum oxide in a mass ratio of (7-9):(9-11):(17-19).

[0022] Furthermore, the corundum has a particle size of 5-8 mm, 3-5 mm, 1-3 mm, or 0.074-1 mm, with the 5-8 mm particle size corundum accounting for 40%-55% of the mass, the 3-5 mm particle size corundum accounting for 25%-40% of the mass, the 1-3 mm particle size corundum accounting for 10%-20% of the mass, and the 0.074-1 mm particle size corundum accounting for 2%-5% of the mass.

[0023] Furthermore, the magnesium aluminum spinel has a particle size of 5-8 mm, 3-5 mm, and 1-3 mm, with the 5-8 mm particle size accounting for 45%-60% of the mass, the 3-5 mm particle size accounting for 20%-30% of the mass, and the 1-3 mm particle size accounting for 15%-20% of the mass.

[0024] The above technical solution achieves dense packing of aggregates by using continuous gradation, reduces the apparent porosity of unshaped refractories, optimizes the pore size and morphological distribution, and improves the thermal shock resistance of unshaped refractories by adjusting the gradient buffer of thermal expansion differences through particle gradation.

[0025] This invention also provides a method for preparing the aforementioned high thermal shock resistant monolithic refractory material, specifically as follows: corundum and magnesium aluminum spinel are sieved according to particle size to remove impurities and excessive particles, dried, placed in a mixer, and stirred for 3-5 minutes. Then, quartz glass powder is added and stirred for 2-3 minutes. The well-stirred binder is added and stirred for 5-6 minutes. Nanoparticles, polyaluminum phosphate, and sodium tripolyphosphate are added and stirred for 20-30 minutes. The mixture is then dried at 200-250℃ for 12-14 hours, calcined at 1600-1800℃ for 2-3 hours, cooled to 1000-1200℃ and held for 3-4 hours, cooled to 600-700℃ and held for 2-3 hours, cooled to 200-300℃ and held for 1-1.5 hours, naturally cooled, and packaged to obtain the high thermal shock resistant monolithic refractory material.

[0026] The above technical solutions enable the corundum and magnesium aluminum spinel aggregates to be graded and sieved according to particle size, avoiding stress concentration caused by large aggregate particles or abnormal high-temperature liquid phase formation caused by impurities. During the mixing process, corundum and magnesium aluminum spinel are mixed first, and then quartz glass powder is added, which allows the quartz glass powder to be evenly coated on the surface of the aggregates, avoiding uneven distribution of mullite formed by the reaction of quartz glass powder and alumina at high temperatures. The use of gradient heating and segmented heat preservation processes can optimize the microstructure and thermal shock resistance.

[0027] Compared with existing technologies, the high thermal shock resistant monolithic refractory material and its preparation method provided by this invention have the following technical advantages:

[0028] (1) The present invention uses high alumina cement, alumina sol and silica powder as a binder to reduce the overall expansion rate of the material, improve the interfacial bonding strength and crack resistance during thermal shock.

[0029] (2) The present invention uses a hydrothermal method to prepare alumina sol with low acid and high solid content, which reduces the difference in thermal expansion, buffers thermal shock, and thus improves the thermal shock resistance of the unshaped refractory material.

[0030] (3) The present invention uses nano carbon black, nano cerium oxide and nano alumina to form nano powder. Through the synergistic mechanism of thermal conductivity regulation, grain refinement and interface strengthening, the thermal shock resistance of the unshaped refractory material is significantly improved. Detailed Implementation

[0031] The following description, in conjunction with specific embodiments, provides further details, but the present invention is not limited to these embodiments. Those skilled in the art can make various modifications based on the fundamental principles of the present invention, but all modifications that do not depart from the fundamental principles of the present invention are within its scope.

[0032] Unless otherwise specified, all raw materials described in this specific embodiment are commercially available.

[0033] Example 1

[0034] A highly thermally shock resistant monolithic refractory material, comprising the following components in parts by weight:

[0035] 70g corundum, 60g magnesium aluminum spinel, 35g binder, 20g nano-powder, 15g quartz glass powder, 8g polyaluminum phosphate, 3g sodium tripolyphosphate.

[0036] The binder is composed of high-alumina cement, alumina sol and silica powder in a mass ratio of 10:7:3; the nanopowder is composed of nano carbon black, nano cerium oxide and nano alumina in a mass ratio of 5:7:15.

[0037] The preparation method of aluminum sol is as follows: 500g of aluminum isopropoxide is added to a reaction vessel, and 750g of deionized water that has been boiled and cooled to 40℃ is added dropwise at a rate of 10mL / min while stirring at 300rpm. The temperature in the reaction vessel is controlled to be <50℃ during the dropwise addition. After the dropwise addition is completed, stirring is continued for 30min. The temperature is increased to 85℃ at a rate of 5℃ / min, and the condenser is turned on at the same time. The temperature is maintained for 2h. Isopropanol is recovered by distillation, and the mixture is cooled. 10g of concentrated nitric acid with a mass percentage of 65% is added, and the mixture is stirred evenly. The temperature is increased to 220℃ at a rate of 10℃ / min, and the mixture is kept at this temperature for 20h. After cooling, the mixture is filtered through a 500-mesh filter to obtain aluminum sol.

[0038] The corundum has particle sizes of 5mm, 3mm, 1mm, and 0.074mm. The 5mm corundum accounts for 40% of the mass, the 3mm corundum accounts for 40% of the mass, the 1mm corundum accounts for 15% of the mass, and the 0.074mm corundum accounts for 5% of the mass.

[0039] Magnesium aluminum spinel has particle sizes of 5mm, 3mm and 1mm. The 5mm particle size magnesium aluminum spinel accounts for 60% of the mass, the 3mm particle size magnesium aluminum spinel accounts for 20% of the mass, and the 1mm particle size magnesium aluminum spinel accounts for 20% of the mass.

[0040] The preparation method of high thermal shock resistant monolithic refractory material is as follows: corundum and magnesium aluminum spinel are sieved according to particle size to remove impurities and excessive particles, dried, placed in a mixer and stirred for 3 minutes, then quartz glass powder is added and stirred for 2 minutes, then the well-stirred binder is added and stirred for 5 minutes, then nano-micro powder, polyaluminum phosphate and sodium tripolyphosphate are added and stirred for 20 minutes, then dried at 200℃ for 12 hours, calcined at 1600℃ for 2 hours, cooled to 1000℃ and held for 3 hours, cooled to 600℃ and held for 2 hours, cooled to 200℃ and held for 1 hour, naturally cooled, and packaged to obtain high thermal shock resistant monolithic refractory material.

[0041] Example 2

[0042] A highly thermally shock resistant monolithic refractory material, comprising the following components in parts by weight:

[0043] 80g corundum, 50g magnesium aluminum spinel, 20g binder, 12g nano-powder, 10g quartz glass powder, 3g polyaluminum phosphate, 1g sodium tripolyphosphate;

[0044] The binder is composed of high-alumina cement, alumina sol and silica powder in a mass ratio of 15:11:6; the nanopowder is composed of nano carbon black, nano cerium oxide and nano alumina in a mass ratio of 9:12:20.

[0045] The preparation method of aluminum sol is as follows: 600g of aluminum isopropoxide is added to a reaction vessel, and 1020g of deionized water that has been boiled and cooled to 45℃ is added dropwise at a rate of 15mL / min while stirring at 400rpm. The temperature in the reaction vessel is controlled to be <50℃ during the dropwise addition. After the dropwise addition is completed, stirring is continued for 50min. The temperature is increased to 90℃ at a rate of 5℃ / min, and the condenser is turned on at the same time. The temperature is maintained for 3h. Isopropanol is recovered by distillation, and the mixture is cooled. 10g of concentrated nitric acid with a mass percentage of 70% is added, and the mixture is stirred evenly. The temperature is increased to 230℃ at a rate of 10℃ / min, and the mixture is kept at this temperature for 22h. After cooling, the mixture is filtered through a 500-mesh filter to obtain aluminum sol.

[0046] The corundum has particle sizes of 8mm, 5mm, 3mm and 1mm. The 8mm corundum accounts for 55% of the mass, the 5mm corundum accounts for 25%, the 3mm corundum accounts for 18%, and the 1mm corundum accounts for 2%.

[0047] The particle sizes of magnesium aluminum spinel are 8mm, 5mm and 3mm. The 8mm particle size magnesium aluminum spinel accounts for 50% of the mass, the 5mm particle size magnesium aluminum spinel accounts for 30% of the mass, and the 3mm particle size magnesium aluminum spinel accounts for 20% of the mass.

[0048] The preparation method of high thermal shock resistant monolithic refractory material is as follows: Corundum and magnesium aluminum spinel are sieved according to particle size to remove impurities and excessive particles, dried, placed in a mixer and stirred for 5 minutes, then quartz glass powder is added and stirred for 3 minutes, then the well-stirred binder is added and stirred for 6 minutes, then nano-micro powder, polyaluminum phosphate and sodium tripolyphosphate are added and stirred for 30 minutes, then dried at 250℃ for 14 hours, calcined at 1800℃ for 3 hours, cooled to 1200℃ and held for 4 hours, cooled to 700℃ and held for 3 hours, cooled to 300℃ and held for 1.5 hours, naturally cooled, and packaged to obtain high thermal shock resistant monolithic refractory material.

[0049] Example 3

[0050] A highly thermally shock resistant monolithic refractory material, comprising the following components in parts by weight:

[0051] 75g corundum, 55g magnesium aluminum spinel, 28g binder, 18g nanopowder, 13g quartz glass powder, 5g polyaluminum phosphate, 2g sodium tripolyphosphate.

[0052] The binder is composed of high-alumina cement, alumina sol and silica powder in a mass ratio of 13:9:5; the nanopowder is composed of nano carbon black, nano cerium oxide and nano alumina in a mass ratio of 8:11:18.

[0053] The preparation method of aluminum sol is as follows: 550g of aluminum isopropoxide is added to a reaction vessel, and 880g of deionized water that has been boiled and cooled to 43℃ is added dropwise at a rate of 13mL / min while stirring at 350rpm. The temperature in the reaction vessel is controlled to be <50℃ during the dropwise addition. After the dropwise addition is completed, stirring is continued for 40min. The temperature is increased to 88℃ at a rate of 5℃ / min, and the condenser is turned on at the same time. The temperature is maintained for 2.5h. Isopropanol is recovered by distillation, and the mixture is cooled. 10g of concentrated nitric acid with a mass percentage of 68% is added and stirred evenly. The temperature is increased to 225℃ at a rate of 10℃ / min and the reaction is maintained for 21h. The mixture is then cooled and filtered through a 500-mesh filter to obtain aluminum sol.

[0054] The corundum has particle sizes of 7mm, 4mm, 2mm, and 0.091mm. The 7mm corundum accounts for 50% of the mass, the 4mm corundum accounts for 30%, the 2mm corundum accounts for 15%, and the 0.091mm corundum accounts for 5%.

[0055] The particle sizes of magnesium aluminum spinel are 6mm, 4mm and 2mm. The 6mm particle size magnesium aluminum spinel accounts for 57% of the mass, the 4mm particle size magnesium aluminum spinel accounts for 25% of the mass, and the 2mm particle size magnesium aluminum spinel accounts for 18% of the mass.

[0056] The preparation method of high thermal shock resistant monolithic refractory material is as follows: Corundum and magnesium aluminum spinel are sieved according to particle size to remove impurities and excessive particles, dried, placed in a mixer and stirred for 4 minutes, then quartz glass powder is added and stirred for 2 minutes, then the well-stirred binder is added and stirred for 5 minutes, then nano-micro powder, polyaluminum phosphate and sodium tripolyphosphate are added and stirred for 25 minutes, then dried at 225℃ for 13 hours, calcined at 1700℃ for 2.5 hours, cooled to 1100℃ and held for 3.5 hours, cooled to 650℃ and held for 2.5 hours, cooled to 250℃ and held for 1.2 hours, naturally cooled, and packaged to obtain high thermal shock resistant monolithic refractory material.

[0057] Example 4

[0058] The high thermal shock resistant amorphous refractory material and its preparation method in this embodiment are similar to those in Example 3. The difference between this embodiment and Example 3 is that the binder in this embodiment is composed of high alumina cement, alumina sol and silica powder in a mass ratio of 14:8:5, and the nanopowder is composed of nano carbon black, nano cerium oxide and nano alumina in a mass ratio of 8:10:19.

[0059] Comparative Example 1

[0060] The unshaped refractory material and its preparation method in this comparative example are similar to those in Example 4. The difference between this comparative example and Example 4 is that an equal amount of high-alumina cement is used instead of alumina sol in the binder of this comparative example.

[0061] Comparative Example 2

[0062] The unshaped refractory material and its preparation method in this comparative example are similar to those in Example 4. The difference between this comparative example and Example 4 is that an equal amount of high-alumina cement is used instead of silica fume in the binder of this comparative example.

[0063] Comparative Example 3

[0064] The unshaped refractory material and its preparation method in this comparative example are similar to those in Example 4. The difference between this comparative example and Example 4 is that an equal amount of tap water is used instead of boiled and cooled deionized water in the preparation method of the aluminum sol in this comparative example.

[0065] Comparative Example 4

[0066] The unshaped refractory material and its preparation method in this comparative example are similar to those in Example 4. The difference between this comparative example and Example 4 is that an equal amount of nano-alumina is used instead of nano-cerium oxide in the nano-powder of this comparative example.

[0067] Comparative Example 5

[0068] The unshaped refractory material and its preparation method in this comparative example are similar to those in Example 4. The difference between this comparative example and Example 4 is that an equal amount of nano-alumina is used instead of nano-carbon black in the nano-powder of this comparative example.

[0069] Comparative Example 6

[0070] The unshaped refractory material and its preparation method in this comparative example are similar to those in Example 4. The difference between this comparative example and Example 4 is that an equal amount of quartz glass powder is used instead of polyaluminum phosphate in this comparative example.

[0071] Test case

[0072] Thermal shock resistance, slag resistance, and corrosion resistance tests: The refractory materials prepared in Examples 1-4 and Comparative Examples 1-6 were added to water and latex and stirred. The mixture was then applied to a test column using conventional methods and dried before testing. The test column was made of graphite carbon fiber cloth and could withstand temperatures up to 2500°C. Thermal shock resistance was expressed as the number of cycles between water cooling and 1400°C that the material could withstand. Corrosion resistance was expressed as the erosion size of steelmaking slag after an erosion test at 1400°C; a larger result indicated lower corrosion resistance. Slag resistance was expressed as the penetration size of the steelmaking slag after the erosion test; a larger result indicated weaker slag resistance.

[0073] Mechanical property testing: The refractory materials prepared in Examples 1-4 and Comparative Examples 1-6 were tested for room temperature flexural strength in accordance with GB / T3001-2017; the refractory materials prepared in Examples 1-4 and Comparative Examples 1-6 were tested for high temperature flexural strength in accordance with GB / T3002-2017.

[0074] The test results are shown in Table 1.

[0075] Table 1 Performance Test Results

[0076]

[0077] Based on the experimental results of Examples 1-4 and Comparative Example 1, it can be seen that the alumina gel film formed by aluminum sol can fill the micropores, improve the bonding performance with the aggregate interface, form a ceramic bonding interface, and thus improve the thermal shock resistance and mechanical properties.

[0078] Based on the experimental results of Examples 1-4 and Comparative Example 2, it can be seen that silicon micropowder can improve the fracture toughness of the material, enhance the cracking resistance, and thus improve the thermal shock resistance and mechanical properties of the material.

[0079] Based on the experimental results of Examples 1-4 and Comparative Example 3, it can be seen that the aluminum sol prepared by boiling and cooling deionized water can avoid particle agglomeration and maximize the effect of aluminum sol. However, the impurities and oxygen contained in deionized water not only introduce a large number of impurities into the refractory material, but also cause the particles to oxidize and agglomerate due to oxygen, which affects the performance.

[0080] Based on the experimental results of Examples 1-4 and Comparative Examples 4-5, it can be seen that in nano-powder, nano-cerium oxide and nano-carbon black can play a role in grain boundary pinning and thermal conduction, thereby improving the thermal shock resistance and mechanical properties of refractory materials by inhibiting crack propagation and avoiding stress concentration.

[0081] Based on the experimental results of Examples 1-4 and Comparative Example 6, it can be seen that polyaluminum phosphate can undergo a solid-phase reaction with alumina in refractory materials at high temperatures to generate aluminum phosphate salt ceramics that fill the spaces between aggregates, thereby improving the interfacial bonding strength and thus enhancing thermal shock resistance and mechanical properties.

[0082] The above embodiments are merely illustrative of the present invention and are not intended to limit the invention. Those skilled in the art should not modify the above embodiments without departing from the spirit and scope of the present invention. All equivalent modifications or alterations made by those skilled in the art without departing from the technical concept of the present invention are still within the protection scope of the present invention.

Claims

1. A highly thermally shock resistant monolithic refractory material, characterized in that, The components include the following parts by weight: 70-80 parts corundum, 50-60 parts magnesium aluminum spinel, 20-35 parts binder, 12-20 parts nano-powder, 10-15 parts quartz glass powder, 3-8 parts polyaluminum phosphate, and 1-3 parts sodium tripolyphosphate. The binder is composed of high-alumina cement, alumina sol and silica powder in a mass ratio of (10-15):(7-11):(3-6); The aluminum sol is prepared as follows: aluminum isopropoxide is added to a reaction vessel, and deionized water is added dropwise while stirring. The temperature in the reaction vessel is controlled to be <50℃ during the dropwise addition. After the dropwise addition is completed, stirring is continued for 30-50 minutes. The temperature is raised to 85-90℃ and kept at that temperature for 2-3 hours. Isopropanol is recovered by distillation. After cooling, concentrated nitric acid is added and stirred evenly. The temperature is raised to 220-230℃ and kept at that temperature for 20-22 hours. After cooling, the mixture is filtered to obtain aluminum sol. The deionized water used in the preparation method of aluminum sol is deionized water that has been boiled and cooled to 40-45℃; the dropping rate of the deionized water is 10-15 mL / min. The nanopowder is composed of nano carbon black, nano cerium oxide and nano aluminum oxide in a mass ratio of (5-9):(7-12):(15-20).

2. The high thermal shock resistant monolithic refractory material according to claim 1, characterized in that, The binder is composed of high-alumina cement, alumina sol and silica powder in a mass ratio of (12-14):(8-10):(5-6).

3. The high thermal shock resistant monolithic refractory material according to claim 1, characterized in that, In the preparation method of aluminum sol, the mass ratio of aluminum isopropoxide to deionized water is 1:(1.5-1.7); the mass ratio of aluminum isopropoxide to concentrated nitric acid is (50-60):1; and the mass percentage of concentrated nitric acid is 65%-70%.

4. The high thermal shock resistant monolithic refractory material according to claim 1, characterized in that, The nanopowder is composed of nano carbon black, nano cerium oxide and nano aluminum oxide in a mass ratio of (7-9):(9-11):(17-19).

5. The high thermal shock resistant monolithic refractory material according to claim 1, characterized in that, The corundum has a particle size of 5-8mm, 3-5mm, 1-3mm, and 0.074-1mm. The corundum with a particle size of 5-8mm accounts for 40%-55% of the mass, the corundum with a particle size of 3-5mm accounts for 25%-40% of the mass, the corundum with a particle size of 1-3mm accounts for 10%-20% of the mass, and the corundum with a particle size of 0.074-1mm accounts for 2%-5% of the mass.

6. The high thermal shock resistant monolithic refractory material according to claim 1, characterized in that, The magnesium aluminum spinel has a particle size of 5-8 mm, 3-5 mm and 1-3 mm, with the 5-8 mm particle size accounting for 45%-60% of the mass, the 3-5 mm particle size accounting for 20%-30% of the mass, and the 1-3 mm particle size accounting for 15%-20% of the mass.

7. The method for preparing the high thermal shock resistant monolithic refractory material according to any one of claims 1-6, characterized in that, Specifically, corundum and magnesium aluminum spinel are sieved according to particle size to remove impurities and excessive particles, dried, and placed in a mixer for 3-5 minutes. Then, quartz glass powder is added and stirred for 2-3 minutes. The binder is then added and stirred for 5-6 minutes. Nanoparticles, polyaluminum phosphate, and sodium tripolyphosphate are added and stirred for 20-30 minutes. The mixture is then dried at 200-250℃ for 12-14 hours, calcined at 1600-1800℃ for 2-3 hours, cooled to 1000-1200℃ and held for 3-4 hours, cooled to 600-700℃ and held for 2-3 hours, cooled to 200-300℃ and held for 1-1.5 hours, allowed to cool naturally, and then packaged to obtain a highly thermally shock resistant amorphous refractory material.

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