Aluminum silicon carbide carbon brick for steel smelting and its preparation method

Abstract

The application discloses a kind of aluminium silicon carbide carbon brick refractory materials for steel smelting and preparation method thereof, it is related to refractory material technical field, by introducing specific compound stabilizer and optimizing particle size and adding amount, inhibit aluminum titanate decomposition in 850 ℃-1050 ℃ low-temperature sintering process, make it form stable solid solution with silicon carbide, build aluminum titanate-silicon carbide composite matrix system, and by solid solution strengthening, the hardness of matrix and wear resistance are promoted, while inhibiting silicon carbide high-temperature oxidation;Combined with silicon carbide particle grading and antioxidant synergistic effect, the matrix density and erosion resistance are optimized, the synergistic promotion of thermal shock resistance and wear resistance is realized, the technical problem of aluminum titanate sintering decomposition is solved.

Description

Technical Field

[0001] This invention relates to the field of refractory materials technology, specifically to an aluminum silicon carbide carbon brick refractory material for iron and steel smelting and its preparation method. Background Technology

[0002] As a widely used refractory material in the steel smelting field, silicon carbide alumina carbon bricks play an important role in the lining protection of key parts such as torpedo ladles, blast furnace belly, and furnace waist due to their excellent high temperature resistance and erosion resistance. As steel smelting processes continue to upgrade towards green and low-carbon directions such as high oxygen enrichment, large coal injection, and hydrogen metallurgy, the working conditions faced by equipment linings, such as high temperature alternation, erosion and wear, and chemical corrosion, are becoming increasingly severe. This places higher demands on the comprehensive performance of silicon carbide alumina carbon bricks, prompting the industry to continuously explore and develop new silicon carbide alumina carbon brick refractory materials with better performance.

[0003] Currently, existing aluminum silicon carbide carbon brick matrices are mainly composed of silicon carbide, alumina, and graphite, which presents significant technical shortcomings. On the one hand, silicon carbide has a high coefficient of thermal expansion, which easily generates significant thermal stress within the brick body under the alternating high-temperature conditions of steel smelting, leading to cracking and spalling, severely impacting its service life. On the other hand, to improve thermal shock resistance, the matrix density is usually reduced or low-expansion components are added, but this method leads to a decrease in brick hardness and wear resistance; conversely, improving wear resistance sacrifices thermal shock resistance, making it difficult to achieve both simultaneously. Furthermore, silicon carbide is prone to oxidation at high temperatures, generating SiO2, which loosens the matrix structure, further exacerbating brick erosion and wear, and shortening its service life. In addition, the aluminum titanate powder in existing technologies is prone to decomposition during sintering, failing to stably exert its modifying effect, and sintering energy consumption is high. These problems all restrict the further improvement and application of aluminum silicon carbide carbon brick performance. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide an aluminum silicon carbide carbon brick refractory material for steel smelting and its preparation method. This method, by introducing a specific compounded stabilizer and optimizing the particle size and dosage, inhibits the decomposition of aluminum titanate during low-temperature sintering at 850℃-1050℃, allowing it to form a stable solid solution with silicon carbide, thus constructing an aluminum titanate-silicon carbide composite matrix system. The solid solution strengthens and enhances the matrix's hardness and wear resistance while simultaneously inhibiting high-temperature oxidation of silicon carbide. Furthermore, by combining the silicon carbide particle size distribution with the synergistic effect of antioxidants, the matrix density and erosion resistance are optimized, achieving a synergistic improvement in thermal shock resistance and wear resistance, thus solving the technical problem of aluminum titanate decomposition during sintering.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: an aluminum silicon carbide carbon brick refractory material for iron and steel smelting, characterized in that, by weight percentage, the raw material composition is as follows: 8%-18% aluminum titanate powder, 22%-38% silicon carbide particles, 12%-24% alumina, 6%-14% graphite, 4%-9% binder, 0.5%-3.5% stabilizer, 0.8%-4.5% additives, with the balance being unavoidable impurities;

[0006] The matrix of the refractory material is an aluminum titanate-silicon carbide composite matrix.

[0007] Furthermore, the aluminum titanate powder has a particle size of 1-10 μm and a purity of ≥98%. This particle size range ensures that the aluminum titanate powder is uniformly dispersed in the matrix, allowing for sufficient contact with the silicon carbide particles and stabilizer. This facilitates the formation of a stable composite matrix and reduces the decomposition rate of aluminum titanate. Aluminum titanate has an extremely low coefficient of thermal expansion and excellent thermal shock resistance, effectively alleviating the thermal stress generated in the brick during alternating high temperatures and preventing cracking. The silicon carbide particles are graded and arranged in a 1-3 mm range. The particles are coarse, 0.1-1mm are medium, and ≤0.074mm are fine. The coarse particles account for 30%-45% of the total mass of silicon carbide, the medium particles account for 30%-40%, and the fine powder accounts for 15%-30%. The purity of silicon carbide is ≥97%. The gradation design can improve the matrix density. The coarse particles play a supporting role in the skeleton, while the medium and fine particles fill the gaps. At the same time, the fine powder is fully mixed with aluminum titanate powder and stabilizer to promote the formation of solid solution, further improve the matrix bonding strength, and synergistically inhibit the decomposition of aluminum titanate.

[0008] Furthermore, the stabilizer is one or more of MgTi2O5, MgO, and Fe2O3 in combination, with a particle size ≤5μm and a purity ≥97%. The mechanism of action of the stabilizer is that MgTi2O5, MgO, and Fe2O3 can all form stable solid solutions with aluminum titanate, wherein Mg... 2+ Fe 3+ ionic radius and Al 3+ Similarly, it can gently dissolve into the aluminum titanate lattice, causing lattice distortion, enhancing the internal interaction forces of the crystal, and locking Al. 3+The MgTi2O5 stabilizer prevents ions from escaping from the crystal lattice, thus fundamentally inhibiting the decomposition of aluminum titanate. MgTi2O5 can also promote the low-temperature synthesis of aluminum titanate, further enhancing its thermal stability. In the stabilizer, if used in combination, the mass ratio of MgTi2O5 to MgO is 1-3:1, and the mass ratio of MgTi2O5 to Fe2O3 is 2-4:1. The preferred addition amount is 1.0%-2.5%. If the addition amount is too low, it will not effectively inhibit decomposition, and if the addition amount is too high, it will affect the thermal shock resistance and density of the composite matrix. When the stabilizer addition amount is 1.5%, the decomposition rate of aluminum titanate after holding at 1050℃ for 3 hours is ≤5%, and it can stably exert its modifying effect.

[0009] Furthermore, the alumina is fused white corundum or high-alumina powder, wherein the particle size of fused white corundum is 0.1-1 mm, the particle size of high-alumina powder is ≤0.074 mm, and the purity of alumina is ≥92%. As an auxiliary component of the matrix, alumina can improve the high-temperature resistance and corrosion resistance of the brick. It works synergistically with aluminum titanate, silicon carbide, and stabilizers to optimize the matrix structure. At the same time, it can react with excess stabilizers to generate stable phases such as spinel, further improving the stability of the system. The graphite is natural flake graphite with a particle size ≤0.1 mm and a fixed carbon content ≥95%. Graphite has good lubricity and high-temperature resistance, which can reduce the friction coefficient of the brick and improve its wear resistance. It can also improve the thermal shock resistance of the brick. Moreover, its presence can form a reducing atmosphere during sintering, which helps to inhibit the oxidative decomposition of aluminum titanate.

[0010] Furthermore, the binder is a phenolic resin or a modified phenolic resin, wherein the modified phenolic resin is a boron-modified or silicon-modified phenolic resin. The binder can tightly bind the raw material particles to form a stable brick structure. The modified phenolic resin can further improve the bonding strength and high-temperature resistance, preventing the binder from decomposing at high temperatures and causing the brick to become porous. At the same time, its decomposition products can form a carbon network inside the brick, which helps stabilize aluminum titanate. The additive is a compound of antioxidant and dispersant. The antioxidant is one or two of metallic aluminum powder and metallic silicon powder, and the dispersant is sodium tripolyphosphate or sodium hexametaphosphate. The mass ratio of antioxidant to dispersant is 3-5:1. The antioxidant can further inhibit the high-temperature oxidation of silicon carbide and graphite, and can also react with TiO2 produced by the decomposition of aluminum titanate to reduce the decomposition of aluminum titanate. The dispersant can uniformly disperse the raw materials (especially aluminum titanate powder and stabilizer), avoid agglomeration, improve the uniformity and density of the brick, and ensure that the stabilizer and aluminum titanate are in full contact to play an inhibitory role in decomposition.

[0011] Furthermore, the composite matrix is ​​formed by the interaction of aluminum titanate powder and silicon carbide particles during low-temperature sintering, and aluminum titanate and silicon carbide form a stable solid solution, with a mass ratio of aluminum titanate to silicon carbide of 1:1.2-2.8.

[0012] On the other hand, a method for preparing aluminum silicon carbide carbon brick refractory material for iron and steel smelting, the method comprising:

[0013] S1: Weigh out the aluminum titanate powder, silicon carbide particles, alumina, graphite, binder, stabilizer and additives by weight percentage, and set aside for later use;

[0014] S2: First, put aluminum titanate powder, silicon carbide particles, alumina, graphite, stabilizer and additives into a mixer and dry mix for 15-30 minutes until uniform; then add binder and wet mix for 20-40 minutes to obtain uniform mud.

[0015] S3: Place the obtained clay into a mold and press it into shape using a press at a pressure of 15-30MPa to obtain a brick blank;

[0016] S4: Place the formed brick blanks into a drying oven and dry them until the moisture content of the brick blanks is ≤0.5%;

[0017] S5: The dried brick blanks are fed into a sintering furnace and heated to 850-1050℃ under an inert atmosphere for 2-5 hours, then cooled to room temperature to obtain silicon carbide aluminum carbide carbon brick refractory material. The sintering temperature is controlled at 850-1050℃ to avoid the range of severe decomposition of aluminum titanate, inhibiting its decomposition from a temperature perspective, while achieving low-temperature densification and reducing energy consumption. The slow heating and cooling rate can avoid the generation of thermal stress inside the brick body and prevent the aggravation of lattice distortion of aluminum titanate due to sudden temperature changes, thereby reducing decomposition. The inert atmosphere can prevent the raw materials from oxidizing during the sintering process, especially preventing the oxidation and decomposition of aluminum titanate. Vacuum sintering can be used to further isolate oxygen and improve the stability of aluminum titanate. A trace amount of Ti3AlC2 powder (accounting for 0.3%-1.0% of the total weight of raw materials) can be introduced during the sintering process. It can work synergistically with the stabilizer to further improve the thermal stability of aluminum titanate and promote the densification of the composite matrix, thereby improving the mechanical properties of the brick body.

[0018] Furthermore, in S2, the dry mixing speed is 200-300 r / min, and the wet mixing speed is 150-250 r / min; in S3, after pressing and molding, a pressure holding treatment is adopted, and the pressure holding time is 3-8 min.

[0019] Furthermore, in step S4, the drying process is carried out in stages: first, drying at 80-90℃ for 12-24 hours, and then drying at 100-120℃ for 12-24 hours.

[0020] Furthermore, in step S5, the inert atmosphere is nitrogen or argon, and the gas flow rate is 0.3-0.8 m³ / s. 3 / h, vacuum sintering can be used as an aid, with the vacuum level controlled at 10. -2 -10-3 Pa.

[0021] Compared with existing technologies, the new aluminum silicon carbide carbon brick refractory material for iron and steel smelting and its preparation method have the following advantages:

[0022] This invention effectively inhibits the decomposition of aluminum titanate during sintering by introducing specific stabilizers and optimizing the sintering process, enabling it to form a stable aluminum titanate-silicon carbide composite matrix system. This fully leverages the extremely low coefficient of thermal expansion of aluminum titanate, significantly alleviating thermal stress in the brick. Simultaneously, solid solution strengthening enhances the matrix's hardness and wear resistance, while suppressing high-temperature oxidation of silicon carbide. The synergistic effect of graded silicon carbide particles and antioxidants further optimizes the matrix's density and erosion resistance. The low-temperature sintering process reduces energy consumption, and segmented drying and inert atmosphere protection prevent thermal stress cracking and oxidative decomposition, significantly extending the brick's service life and achieving a synergistic improvement in thermal shock resistance and wear resistance.

[0023] Other advantages, objectives and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination or study, or may be learned from the practice of the invention. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0025] Figure 1 A flowchart of a method for preparing aluminum silicon carbide carbon brick refractory material for iron and steel smelting;

[0026] Figure 2 This is a flowchart of method S4 for preparing aluminum silicon carbide carbon brick refractory material for iron and steel smelting. Detailed Implementation

[0027] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0028] Example 1

[0029] A silicon carbide aluminum carbide carbon brick refractory material for steel smelting, comprising the following raw materials by weight percentage: 8% aluminum titanate powder (particle size 1-5μm, purity 98%), 38% silicon carbide particles (45% coarse particles 1-3mm, 30% medium particles 0.1-1mm, 25% fine powder ≤0.074mm, purity 97%), 24% alumina (fused white corundum, particle size 0.1-1mm, purity 92%), 6% graphite (natural flake graphite, particle size ≤0.1mm, fixed carbon content 95%), 4% binder (phenolic resin), 0.5% stabilizer (MgTi2O5, particle size ≤5μm, purity 97%), and 0.8% additive (aluminum metal powder and sodium tripolyphosphate compounded, mass ratio 3:1); the mass ratio of aluminum titanate to silicon carbide is 1:4.75, and the solid solution grain size is 2.5-3μm.

[0030] like Figure 1 As shown, its preparation method is as follows:

[0031] Using an electronic balance with an accuracy of 0.0001g, weigh each raw material according to the above weight percentage, with the weighing error controlled within ±0.5%. Place the aluminum titanate powder and MgTi2O5 stabilizer in an 80℃ vacuum drying oven for 2 hours. Remove unqualified particles by screening silicon carbide particles and pulverize graphite to a particle size ≤0.1mm. After weighing, place each raw material separately and label it to avoid confusion.

[0032] A dual-speed mixer is used. First, aluminum titanate powder, silicon carbide particles, alumina, graphite, stabilizer and additives are put into the mixing chamber and dry-mixed at 200 r / min for 30 min until they are uniform and free of lumps. Then, phenolic resin is slowly added and wet-mixed at 150 r / min for 40 min to obtain uniform mud. After removal, it is sealed and stored and molded within 1.5 hours.

[0033] Select a steel mold with the same size as the target brick, and coat the inner wall with a release agent made of graphite powder and machine oil; fill the mold with clay evenly, tap the side wall of the mold to remove the gaps, and scrape off the excess clay on the surface; place it in a hydraulic press and press it into shape under a pressure of 15MPa for 8 minutes; slowly release the pressure (5MPa / min), and after demolding, check the appearance of the brick blank, remove defective products, and place them on a clean pallet.

[0034] like Figure 2 As shown, the brick blanks were placed in an electric heating drying oven and pre-dried at 80℃ for 24 hours, followed by deep drying at 100℃ for 24 hours. Three brick blanks were randomly selected to test the moisture content, with an average value of 0.42% (≤0.5%). After the drying was qualified, the brick blanks were taken out and cooled to room temperature.

[0035] The brick blanks are placed in an atmosphere sintering furnace, and nitrogen gas (flow rate 0.3 m³ / h) is introduced into the furnace. 3Ventilate for 30 minutes to remove air; heat up to 850℃ at 3℃ / min and hold for 5 hours; cool down to below 500℃ at 2℃ / min and allow to cool naturally to room temperature; remove the brick blank, which has no defects in appearance, and obtain aluminum silicon carbide carbon brick.

[0036] Example 2

[0037] A type of aluminum silicon carbide carbon brick refractory material for steel smelting, comprising the following raw material composition by weight percentage: 13% aluminum titanate powder (particle size 3-8μm, purity 99%), 30% silicon carbide particles (38% coarse particles 1-3mm, 35% medium particles 0.1-1mm, 27% fine powder ≤0.074mm, purity 98%), 18% alumina (high alumina powder, particle size ≤0.074mm, purity 95%), and 10% graphite (natural flakes). The composition includes: graphite (particle size ≤ 0.1 mm, fixed carbon content 96%), binder 6.5% (boron-modified phenolic resin), stabilizer 1.5% (MgTi2O5 and MgO compound, mass ratio 2:1, particle size ≤ 5 μm, purity 97%), additive 2.5% (silicon metal powder and sodium hexametaphosphate compound, mass ratio 4:1), with the balance being unavoidable impurities; aluminum titanate and silicon carbide have a mass ratio of 1:2.31, and the solid solution grain size is 1.5-2 μm.

[0038] Its preparation method is as follows:

[0039] Using an electronic balance with an accuracy of 0.0001g, weigh each raw material according to the above weight percentage, with the weighing error controlled within ±0.5%; place the aluminum titanate powder and compound stabilizer in an 80℃ vacuum drying oven for 2 hours; screen the silicon carbide particles to remove unqualified particles; pulverize the graphite to a particle size ≤0.1mm; shake the boron-modified phenolic resin well and set aside; mix the additives evenly according to the proportion.

[0040] A dual-speed mixer is used. First, aluminum titanate powder, silicon carbide particles, alumina, graphite, compound stabilizer and additives are put into the mixing chamber and dry-mixed at 250 r / min for 22 min until they are uniformly mixed. Then, boron-modified phenolic resin is slowly added and wet-mixed at 200 r / min for 30 min to obtain uniform mud. After being taken out, it is sealed and stored, and molding is carried out within 1 hour.

[0041] Select a steel mold and apply a release agent to the inner wall; fill the mold with clay evenly, tap to release air, and scrape the surface smooth; place it in a hydraulic press and press it into shape under a pressure of 22MPa for 5 minutes; slowly release the pressure, and after demolding, check the appearance of the brick blank. If it is qualified, place it on a pallet.

[0042] The brick blanks were placed in an electric heating drying oven and pre-dried at 85℃ for 18 hours, followed by deep drying at 110℃ for 18 hours. The moisture content was tested, and the average value was 0.38%. After the drying was qualified, the brick blanks were cooled to room temperature.

[0043] The brick blanks are placed in an atmosphere sintering furnace, and argon gas (flow rate 0.5 m³ / h) is introduced. 3 / h), ventilate for 30 minutes to remove air; heat up to 1000℃ at 5℃ / min and hold for 3.5 hours; cool down to below 500℃ at 4℃ / min and allow to cool naturally to room temperature; remove the brick blank to obtain silicon carbide aluminum carbon brick.

[0044] Example 3

[0045] A type of aluminum silicon carbide carbon brick refractory material for steel smelting, with the following raw material composition by weight percentage: 18% aluminum titanate powder (particle size 6-10μm, purity 98.5%), 22% silicon carbide particles (30% coarse particles 1-3mm, 40% medium particles 0.1-1mm, and 30% fine powder ≤0.074mm, purity 97.5%), 12% alumina (a 1:1 mixture of fused white corundum and high alumina powder, with particle sizes of 0.1-1mm and ≤0.074mm respectively, purity 93%), and 14% graphite (natural aluminum oxide). The solid solution contains flake graphite (particle size ≤ 0.1 mm, fixed carbon content 97%), binder 9% (silicon-modified phenolic resin), stabilizer 3.5% (MgTi2O5 and Fe2O3 compounded, mass ratio 3:1, particle size ≤ 5 μm, purity 97%), additive 4.5% (aluminum powder and silicon powder compounded, then mixed with sodium tripolyphosphate at a ratio of 4:1, aluminum powder and silicon powder mass ratio 1:1), with the remainder being unavoidable impurities; aluminum titanate and silicon carbide mass ratio is 1:1.22, and solid solution grain size is 0.5-1 μm.

[0046] Its preparation method is as follows:

[0047] Weigh each raw material according to the above weight percentage using an electronic balance with an accuracy of 0.0001g, and control the weighing error within ±0.5%. Put the aluminum titanate powder, silicon carbide particles, alumina, graphite, stabilizer and additives into a mixer and dry mix at 300r / min for 15min. Then add the silicon-modified phenolic resin and wet mix at 250r / min for 20min to obtain a uniform mud.

[0048] Select a steel mold and apply a release agent to the inner wall; fill the mold with clay evenly, tap to release air, and scrape the surface smooth; place it in a hydraulic press and press it into shape under a pressure of 30MPa for 3 minutes to obtain a brick blank; slowly release the pressure, demold, and check the appearance of the brick blank. If it is qualified, place it on a pallet.

[0049] Place the brick blanks in a drying oven and dry them at 90℃ for 12 hours, then at 120℃ for 12 hours, until the moisture content is ≤0.5%.

[0050] The brick blanks were fed into a sintering furnace, protected with nitrogen (flow rate 0.8 m³ / h), heated to 1050℃ at 8℃ / min, held for 2 hours, cooled to below 500℃ at 6℃ / min, and allowed to cool naturally to room temperature. At the same time, 0.6% Ti3AlC2 powder was introduced to obtain silicon carbide aluminum carbon bricks.

[0051] Comparative Example 1

[0052] A silicon carbide carbon brick refractory material for steel smelting, by weight percentage, comprises the following raw materials: 13% aluminum titanate powder (particle size 3-8μm, purity 99%), 30% silicon carbide particles (38% coarse particles 1-3mm, 35% medium particles 0.1-1mm, 27% fine powder ≤0.074mm, purity 98%), 18% alumina (high alumina powder, particle size ≤0.074mm, purity 95%), 10% graphite (natural flake graphite, particle size ≤0.1mm, fixed carbon content 96%), 6.5% binder (boron-modified phenolic resin), 2.5% additives (a mixture of metallic silicon powder and sodium hexametaphosphate, mass ratio 4:1), with the remainder being unavoidable impurities; the mass ratio of aluminum titanate to silicon carbide is 1:2.31, and without the action of a stabilizer, a stable solid solution cannot be formed, and aluminum titanate is easily decomposed.

[0053] Its preparation method is as follows:

[0054] Weigh each raw material according to the above weight percentages (without adding any stabilizers), ensuring that the weighing error is ≤ ±0.5%;

[0055] Aluminum titanate powder, silicon carbide particles, alumina, graphite and additives are put into a mixer and dry-mixed at 250 r / min for 22 min. Then boron-modified phenolic resin is added and wet-mixed at 200 r / min for 30 min to obtain a uniform mud.

[0056] The clay is placed into a mold and pressed under a pressure of 22MPa for 5 minutes to obtain a brick blank.

[0057] Place the brick blanks in a drying oven and dry them at 85℃ for 18 hours, then at 110℃ for another 18 hours, until the moisture content is ≤0.5%.

[0058] The brick blanks are fed into a sintering furnace, protected by argon gas (flow rate 0.5 m³ / h), heated to 1000℃ at 5℃ / min, held for 3.5 h, cooled to below 500℃ at 4℃ / min, and allowed to cool naturally to room temperature to obtain silicon carbide aluminum carbon bricks.

[0059] Comparative Example 2

[0060] A silicon carbide aluminum carbide carbon brick refractory material for steel smelting, with a raw material composition identical to that of Example 2 by weight percentage: 13% aluminum titanate powder (particle size 3-8μm, purity 99%), 30% silicon carbide particles (38% coarse particles 1-3mm, 35% medium particles 0.1-1mm, 27% fine powder ≤0.074mm, purity 98%), and 18% alumina (high alumina powder, particle size ≤0.074mm, purity 95%). The composition includes: 10% graphite (natural flake graphite, particle size ≤0.1mm, fixed carbon content 96%), 6.5% binder (boron-modified phenolic resin), 1.5% stabilizer (MgTi2O5 and MgO compound, mass ratio 2:1, particle size ≤5μm, purity 97%), 2.5% additive (silicon metal powder and sodium hexametaphosphate compound, mass ratio 4:1), with the remainder being unavoidable impurities; the mass ratio of aluminum titanate to silicon carbide is 1:2.31.

[0061] Its preparation method is as follows:

[0062] Weigh each raw material according to the above weight percentages, ensuring that the weighing error is ≤ ±0.5%;

[0063] Aluminum titanate powder, silicon carbide particles, alumina, graphite, stabilizer and additives are put into a mixer and dry-mixed at 250 r / min for 22 min. Then boron-modified phenolic resin is added and wet-mixed at 200 r / min for 30 min to obtain uniform mud.

[0064] The clay is placed into a mold and pressed under a pressure of 22MPa for 5 minutes to obtain a brick blank.

[0065] Place the brick blanks in a drying oven and dry them at 85℃ for 18 hours, then at 110℃ for another 18 hours, until the moisture content is ≤0.5%.

[0066] The brick blanks are fed into a sintering furnace, protected by argon gas (flow rate 0.5 m³ / h), heated to 1150℃ at 5℃ / min, held for 3.5 h, cooled to below 500℃ at 4℃ / min, and then allowed to cool naturally to room temperature to obtain silicon carbide aluminum carbon bricks.

[0067] Performance testing:

[0068] Decomposition rate test of aluminum titanate: Phase analysis of brick samples was performed using X-ray diffraction. The characteristic peak intensities of aluminum titanate, corundum (Al2O3), and rutile (TiO2) in the brick were measured. The decomposition rate of aluminum titanate was calculated based on the decomposition reaction formula. Test conditions: Cu target, Kα rays, tube voltage 40kV, tube current 40mA, scanning range 2θ=10°-80°, scanning speed 5° / min.

[0069] Thermal expansion coefficient test: The thermal expansion meter was used for the test. The sample was processed into a cylindrical shape of φ5mm×50mm. The test temperature range was 25℃-1000℃, the heating rate was 5℃ / min, and the air atmosphere was used. The length change at different temperatures was recorded, and the average thermal expansion coefficient was calculated.

[0070] 1100℃ water-cooled thermal shock resistance test: The sample is processed into a 100mm×100mm×50mm cuboid. The sample is placed in a muffle furnace, heated to 1100℃, held for 30 minutes, and then quickly removed and quenched in distilled water at 25℃ for 5 minutes. After removal, it is allowed to air dry naturally. The sample is observed to see if cracks or peeling occur. The above steps are repeated until the sample shows obvious cracks (crack length ≥5mm) or peeling area ≥10%. The number of cycles at this time is recorded as the thermal shock resistance test.

[0071]

[0072] Rockwell hardness test: The Rockwell hardness tester was used with a test load of 150 kgf and a diamond indenter. Before the test, the sample surface was polished to a smooth and flat surface. Five different test points were selected for each sample, and the average value was taken as the Rockwell hardness value.

[0073] Wear test: Using a pin-disc wear tester with a wear test device, the sample was processed into a 50mm×50mm×10mm disc, the wear part was a Si3N4 ceramic disc, the load was 50N, the rotation speed was 200r / min, and the wear time was 60min. Before and after the test, the sample mass was weighed using an electronic balance (accuracy 0.0001g) and the wear amount was calculated.

[0074] Silicon carbide oxidation rate test: The gravimetric method was used. The sample was processed into a cube of 20mm×20mm×20mm, the initial mass was weighed, and it was placed in a muffle furnace and kept at 1100℃ in air atmosphere for 3 hours. After cooling to room temperature, the mass after oxidation was weighed, and the silicon carbide oxidation rate was calculated according to the silicon carbide oxidation reaction formula.

[0075]

[0076] In summary, this invention effectively solves the technical bottleneck of easy decomposition of aluminum titanate during sintering through a dual-core strategy of stabilizer addition and sintering process optimization. As can be clearly seen from the table data, the decomposition rate of aluminum titanate in each embodiment is controlled within 5%, which is much lower than that of the comparative example without stabilizer addition and without optimized sintering temperature. At the same time, the aluminum silicon carbide carbon bricks prepared in the embodiments are significantly better than those in the comparative example in terms of coefficient of thermal expansion, thermal shock resistance, hardness, wear resistance and inhibition of silicon carbide oxidation, which fully demonstrates the effectiveness and superiority of the technical solution of this invention.

[0077] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A silicon carbide aluminum carbide carbon brick refractory material for iron and steel smelting, characterized in that, The raw material composition by weight percentage is as follows: 8%-18% aluminum titanate powder, 22%-38% silicon carbide particles, 12%-24% alumina, 6%-14% graphite, 4%-9% binder, 0.5%-3.5% stabilizer, 0.8%-4.5% additives, with the balance being unavoidable impurities. The binder is a phenolic resin or a modified phenolic resin, wherein the modified phenolic resin is a boron-modified or silicon-modified phenolic resin. The stabilizer is MgTi2O5 or a mixture of MgTi2O5 and MgO or a mixture of MgTi2O5 and Fe2O3. The particle size of the stabilizer is ≤5μm and the purity is ≥97%. The additive is a compound of antioxidant and dispersant. The antioxidant is one or two of metallic aluminum powder and metallic silicon powder, and the dispersant is sodium tripolyphosphate or sodium hexametaphosphate. The mass ratio of antioxidant to dispersant is 3-5:

1. The matrix of the refractory material is an aluminum titanate-silicon carbide composite matrix.

2. The aluminum silicon carbide carbon brick refractory material for iron and steel smelting according to claim 1, characterized in that, The aluminum titanate powder has a particle size of 1-10 μm and a purity of ≥98%; the silicon carbide particles are graded, with 1-3 mm as coarse particles, 0.1-1 mm as medium particles, and ≤0.074 mm as fine powder, wherein coarse particles account for 30%-45% of the total mass of silicon carbide, medium particles account for 30%-40%, and fine powder accounts for 15%-30%, and the purity of silicon carbide is ≥97%.

3. The aluminum silicon carbide carbon brick refractory material for iron and steel smelting according to claim 1, characterized in that, The alumina is fused white corundum or high-alumina powder, wherein the particle size of fused white corundum is 0.1-1 mm, the particle size of high-alumina powder is ≤0.074 mm, and the alumina purity is ≥92%; the graphite is natural flake graphite with a particle size ≤0.1 mm and a fixed carbon content ≥95%.

4. The aluminum silicon carbide carbon brick refractory material for iron and steel smelting according to claim 1, characterized in that, The composite matrix is ​​formed by the interaction of aluminum titanate powder and silicon carbide particles during low-temperature sintering, and aluminum titanate and silicon carbide form a stable solid solution with a mass ratio of aluminum titanate to silicon carbide of 1:1.2-2.

8.

5. A method for preparing an aluminum silicon carbide carbon brick refractory material for iron and steel smelting, used to prepare the aluminum silicon carbide carbon brick refractory material for iron and steel smelting as described in any one of claims 1-4, characterized in that, The method includes: S1: Weigh out the aluminum titanate powder, silicon carbide particles, alumina, graphite, binder, stabilizer and additives by weight percentage, and set aside for later use; S2: Add aluminum titanate powder, silicon carbide particles, alumina, graphite, stabilizer and additives into a mixer and dry mix for 15-30 minutes until uniform; then add binder and wet mix for 20-40 minutes to obtain uniform mud. S3: Place the obtained clay into a mold and press it into shape using a press at a pressure of 15-30MPa to obtain a brick blank; S4: Place the formed brick blanks into a drying oven and dry them until the moisture content of the brick blanks is ≤0.5%; S5: The dried brick blanks are sent into a sintering furnace and heated to 850-1050℃ under an inert atmosphere for 2-5 hours. Then the temperature is lowered to room temperature to obtain aluminum silicon carbide carbon brick refractory material.

6. The method for preparing an aluminum silicon carbide carbon brick refractory material for iron and steel smelting according to claim 5, characterized in that, In step S2, the dry mixing speed is 200-300 r / min, and the wet mixing speed is 150-250 r / min; in step S3, after pressing and molding, a pressure holding treatment is performed, and the pressure holding time is 3-8 min.

7. The method for preparing an aluminum silicon carbide carbon brick refractory material for iron and steel smelting according to claim 5, characterized in that, In step S4, the drying process is carried out in stages: first, drying at 80-90℃ for 12-24 hours, and then drying at 100-120℃ for 12-24 hours.

8. The method for preparing an aluminum silicon carbide carbon brick refractory material for iron and steel smelting according to claim 5, characterized in that, In step S5, the inert atmosphere is nitrogen or argon, and the gas flow rate is 0.3-0.8 m³ / s. 3 / h, vacuum sintering can be used as an aid, with the vacuum level controlled at 10. -2 -10 -3 Pa.

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