An erosion-resistant ceramic-magnesium-based composite refractory brick and a method for manufacturing the same

Abstract

The application provides an anti-erosion ceramic-magnesium-based composite refractory brick and a preparation method thereof, and belongs to the technical field of ceramic composite magnesium refractory bricks. Raw material components of the refractory brick include ceramic composite material, fused magnesia, boron-nitrogen-doped carbon-silane modified magnesium-aluminum spinel intermediate, fused magnesium-chromium powder, zirconium diboride, silicon powder, silicon-iron-nitride boron composite additive and the like. The boron-nitrogen-doped carbon-silane modified magnesium-aluminum spinel intermediate is prepared by coating fused magnesium-aluminum spinel powder with PEG and boron-nitrogen-doped carbon black, then modifying with a silane coupling agent, and sintering. The ceramic composite material includes tabular corundum particles, micron alumina and ZrO2@SiC whiskers. The silicon-iron-nitride boron composite additive is prepared by ball milling silicon-iron alloy powder, boron nitride powder and PEG2000. The multi-phase synergistic design breaks through the performance short board of traditional single-system refractory bricks, and realizes overall balance and balanced improvement of hardness, wear resistance, corrosion resistance, thermal shock resistance and hydration resistance.

Description

Technical Field

[0001] This invention belongs to the technical field of ceramic composite magnesium refractory bricks, specifically relating to an erosion-resistant ceramic-magnesium-based composite refractory brick and its preparation method. Background Technology

[0002] The performance of refractory materials directly determines the service life, operational safety, and economic benefits of high-temperature industrial kilns. Among them, refractory bricks, as the most traditional and widely used form, play an indispensable role in fields such as steel, cement, glass, and non-ferrous metal smelting. Ceramic materials and magnesia materials are the two core systems constituting high-performance refractory bricks.

[0003] Ceramic refractory bricks primarily use non-oxide or oxide ceramics such as alumina, zirconia, silicon carbide, and silicon nitride as raw materials. The core advantages of these materials lie in their excellent high-temperature resistance, extremely high hardness, and superior chemical stability. For example, high-alumina bricks exhibit good resistance to acidic slag erosion and high-temperature strength; zirconia bricks, thanks to their phase transformation toughening effect, demonstrate excellent thermal shock resistance and slag erosion resistance; while silicon carbide refractories are renowned for their high thermal conductivity, wear resistance, and erosion resistance, and are widely used in harsh environments such as blast furnace tapping troughs and aluminum electrolysis cells. However, traditional single-phase or simple multiphase ceramic refractory bricks are not without flaws. First, most ceramic materials, especially oxide ceramics, have a high coefficient of thermal expansion, resulting in generally poor thermal shock resistance. Under drastic temperature fluctuations during kiln heating and cooling, they are prone to cracking and even spalling, severely affecting their service life. Second, although ceramic materials have high hardness, they are typically brittle, easily subject to surface wear and material loss due to erosion.

[0004] Magnesia refractories are alkaline refractories with magnesium oxide as the main component. Their most prominent advantage is their extremely strong resistance to alkaline slag and iron oxide erosion, making magnesia bricks, magnesia-chrome bricks, and magnesia-carbon bricks the preferred materials for key components such as steelmaking converters, ladles, and cement rotary kiln firing zones. Magnesia-carbon bricks, in particular, by introducing graphite into magnesia, utilize graphite's low thermal conductivity, excellent lubricity, and slag penetration resistance to significantly improve the material's thermal shock resistance and erosion resistance, giving them a dominant position in the modern steel industry. However, magnesia refractories also face severe performance challenges. The primary problem lies in their poor hydration resistance. Magnesia oxide is a strong alkaline oxide that readily reacts with moisture in the air to form magnesium hydroxide, leading to brick pulverization, reduced strength, and severely impacting their storage, transportation, and performance. Secondly, traditional magnesia materials have relatively low high-temperature strength and are prone to creep deformation at high temperatures. In high-speed flowing molten slag, liquid metal, or dusty gas streams, magnesia refractories lack sufficient wear resistance and erosion resistance. Especially for magnesia-carbon bricks with high graphite content, the presence of the graphite phase brings many benefits, but it also makes them more susceptible to wear when subjected to high-speed erosion, leading to damage to the surface structure of the brick and thus accelerating the erosion and penetration of slag.

[0005] Both ceramic-based and magnesia-based refractory bricks have their own shortcomings when facing increasingly demanding modern industrial smelting conditions, especially in terms of insufficient resistance to erosion and abrasion. Existing single-system refractory bricks cannot perfectly meet all performance requirements. Ceramic bricks are wear-resistant but may not be resistant to alkali slag erosion or have poor thermal shock resistance; magnesia bricks have strong resistance to alkali slag erosion, but their wear resistance and erosion resistance need to be improved.

[0006] Therefore, it is necessary to develop new composite refractory bricks that combine the high hardness and high wear resistance of ceramic materials with the strong resistance to alkaline slag erosion of magnesia materials, in order to meet the modern high-temperature industry's demand for "long life, high efficiency and stability" of refractory materials. Summary of the Invention

[0007] To comprehensively improve the hardness, wear resistance, erosion resistance, and thermal shock resistance of refractory bricks, and further enhance their erosion resistance, this invention provides an erosion-resistant ceramic-magnesium-based composite refractory brick and its preparation method. Through multi-phase synergistic design of components such as ceramic composite materials, fused magnesia, boron-nitrogen-doped carbon-silane modified magnesium-aluminum spinel intermediates, fused magnesia-chromium powder, zirconium diboride, silica powder, and ferrosilicon-boron nitride composite additives, this invention overcomes the performance shortcomings of traditional single-system refractory bricks, achieving a comprehensive balance and balanced improvement in hardness, wear resistance, erosion resistance, thermal shock resistance, and hydration resistance. Simultaneously, by developing self-modified intermediates and composite additives, key technical challenges such as interfacial compatibility and hydration degradation are solved, ultimately resulting in a long-life, high-efficiency, and stable composite refractory brick. The specific technical solution is as follows:

[0008] An erosion-resistant ceramic-magnesium composite refractory brick comprises, by weight, the following raw materials: 30-40 parts ceramic composite material, 40-45 parts fused magnesia, 8-10 parts boron-nitrogen-doped carbon-silane modified magnesium-aluminum spinel intermediate, 8-12 parts fused magnesia-chromium powder, 3-5 parts zirconium diboride, 4-6 parts silica powder, 5-8 parts ferrosilicon-boron nitride composite additive, 3.5-4.5 parts thermosetting phenolic resin powder, 0.3-0.6 parts composite dispersant, and 10-14 parts alumina sol;

[0009] The boron-nitrogen-doped carbon-silane modified magnesium-aluminum spinel intermediate is prepared by dispersing PEG and boron-nitrogen-doped carbon black in isopropanol, adjusting the pH to 4.0-4.5, adding fused magnesium-aluminum spinel micro powder, dispersing and distilling to obtain pre-coated spinel, then mixing with silane coupling agent ethanol solution, drying, sintering at 300℃-350℃, and pulverizing. The mass ratio of PEG, boron-nitrogen-doped carbon black, fused magnesium-aluminum spinel micro powder and silane coupling agent is (1.5-2.5):(18-25):(90-100):(2-4). The boron-nitrogen-doped carbon black is prepared by dispersing carbon black, boric acid, melamine and urea in ethanol at a mass ratio of (15-20):(1-2):(2-3):(0.5-0.8), distilling, drying, grinding into precursor powder, sintering at 850℃-900℃, and pulverizing.

[0010] The ceramic composite material comprises plate-shaped corundum particles, micron-sized alumina, and ZrO2@SiC whiskers in a mass ratio of (30-35):(20-22):(12-15); the ZrO2@SiC whiskers are prepared by mixing a solution A of zirconium oxychloride octahydrate, yttrium nitrate hexahydrate, and deionized water with a PEG ethanol solution, adjusting the pH to 2.5-3.0, adding tetraethyl orthosilicate to obtain zirconium-silica sol, then mixing it with an ethanol suspension of SiC whiskers, evaporating and drying the mixture, sintering it at 550℃-600℃ and 1100℃-1200℃ respectively, and then pulverizing it to prepare the composite material.

[0011] The ferrosilicon-boron nitride composite additive is prepared by ball milling ferrosilicon alloy powder, boron nitride powder and PEG2000 in a mass ratio of (70-75):(25-30):(3-5).

[0012] The composite dispersant comprises sodium hexametaphosphate and citric acid in a mass ratio of (0.8-1):1.

[0013] The particle size distribution of the above raw materials is as follows: 3mm < particle size ≤ 5mm accounts for 35wt% to 45wt%, 1mm < particle size ≤ 3mm accounts for 30wt% to 40wt%, 0.088mm < particle size ≤ 1mm accounts for 15wt% to 25wt%, and less than 0.088mm accounts for 5wt% to 10wt%; the particle size distribution of the tabular corundum particles is as follows: 1mm < particle size ≤ 3mm accounts for 40wt% to 50wt%, 0.1mm < particle size ≤ 1mm accounts for 42wt% to 55wt%, and less than 0.1mm accounts for 5wt% to 8wt%.

[0014] The preparation method of the ZrO2@SiC whiskers in the above-mentioned raw materials includes the following steps: Solution A is prepared by mixing 10-15 parts by mass of zirconium oxychloride octahydrate, 0.8-1.2 parts by mass of yttrium nitrate hexahydrate, and 40-60 parts by mass of deionized water; Solution B is prepared by mixing 1.5-2.5 parts by mass of PEG and 30-50 parts by mass of ethanol; Solution A and Solution B are mixed and dispersed evenly, pH is adjusted to 2.5-3.0, and the mixture is allowed to stand. Then, 3-5 parts by mass of tetraethyl orthosilicate are added dropwise while stirring to obtain zirconium-silica sol; 50-60 parts by mass of SiC whiskers are dispersed in 100-120 parts by mass of ethanol to obtain a suspension; the suspension is added to the zirconium-silica sol while stirring, stirred, evaporated, dried, sintered at 550-600℃, sintered at 1100-1200℃, cooled, and pulverized to obtain ZrO2@SiC whiskers.

[0015] In the above method for preparing ZrO2@SiC whiskers, the average molecular weight of the PEG is 600; the sintering time at 550℃~600℃ is 1.5h~2.5h; the sintering time at 1100℃~1200℃ is 3h~4h; and the particle size of the pulverized material is sieved through a 325-400 mesh sieve.

[0016] The preparation method of the boron-nitrogen-doped carbon-silane modified magnesium-aluminum spinel intermediate in the above raw materials includes the following steps: by mass, 1.5 to 2.5 parts of PEG are added to 300 to 350 parts of isopropanol and stirred, 18 to 25 parts of boron-nitrogen-doped carbon black are added and dispersed evenly, the pH is adjusted to 4.0 to 4.5, 90 to 100 parts of fused magnesium-aluminum spinel powder are added, stirred evenly, and the isopropanol is removed by distillation to obtain pre-coated spinel; 2 to 4 parts of silane coupling agent are dissolved in 30 to 40 parts of ethanol, and then mixed evenly with the pre-coated spinel, evaporated and dried, sintered at 300°C to 350°C under nitrogen protection, cooled, and pulverized to obtain the boron-nitrogen-doped carbon-silane modified magnesium-aluminum spinel intermediate.

[0017] In the above method for preparing boron-nitrogen-doped carbon-silane modified magnesium-aluminum spinel intermediate, the average molecular weight of the PEG is 400; the median particle size of the fused magnesium-aluminum spinel micropowder is 20 μm to 30 μm; the silane coupling agent is KH-560; the sintering time at 300℃ to 350℃ is 1.5 h to 2.5 h; and the particle size of the pulverized material is sieved through a 250 mesh to 325 mesh sieve.

[0018] In the above-mentioned method for preparing boron-nitrogen-doped carbon-silane modified magnesium-aluminum spinel intermediate, the method for preparing boron-nitrogen-doped carbon black includes the following steps: by mass parts, 15-20 parts of carbon black, 1-2 parts of boric acid, 2-3 parts of melamine and 0.5-0.8 parts of urea are added to 50-70 parts of ethanol and dispersed evenly; the ethanol is evaporated to remove the ethanol, dried, and ground through a 200-250 mesh sieve to obtain precursor powder; under nitrogen protection, the temperature is raised to 850-900℃ and sintered for 2-3 hours; cooled, and pulverized through a 540-650 mesh sieve to obtain boron-nitrogen-doped carbon black.

[0019] The preparation method of the ferrosilicon-boron nitride composite additive mentioned above includes the following steps: 70-75 parts by mass of ferrosilicon alloy powder, 25-30 parts by mass of boron nitride powder, and 3-5 parts by mass of PEG2000 are mixed, ball-milled, dried under nitrogen protection, and passed through a 150-200 mesh sieve to obtain the ferrosilicon-boron nitride composite additive.

[0020] The above-mentioned method for preparing an erosion-resistant ceramic-magnesium composite refractory brick includes the following steps:

[0021] S1: According to the formula by mass parts, ceramic composite material, fused magnesia, fused magnesia-chromium powder, zirconium diboride, silicon micro powder, ferrosilicon-boron nitride composite additive, thermosetting phenolic resin powder and composite dispersant are mixed evenly. Then, boron-nitrogen doped carbon-silane modified magnesium-aluminum spinel intermediate is added and mixed evenly. Then, aluminum sol is added and mixed into plastic mud. The mixture is then pressed into shape by machine to obtain brick blank.

[0022] S2: The brick blanks are dried, sintered, and cooled to obtain refractory bricks.

[0023] In the above-mentioned refractory brick preparation method S1: the accumulator is accumulating at 20℃~25℃ and 60%~70%RH for 24h~26h; the pressure of the machine pressing is 120MPa~150MPa, and the holding time is 30s~60s.

[0024] In the above-mentioned refractory brick preparation method S2: the drying is carried out at 105℃~115℃ for 24h~48h; the sintering is carried out at 500℃~600℃ for 1.5h~2h, at 900℃~1000℃ for 1.5h~2h, and at 1450℃~1550℃ for 3h~4h.

[0025] The present invention provides an erosion-resistant ceramic-magnesium composite refractory brick and its preparation method, which have the following beneficial effects:

[0026] I. This invention overcomes the performance limitations of traditional single-system refractory bricks through a multi-phase synergistic design involving ceramic phase, magnesium-based phase, functional intermediates, and composite additives. It achieves a comprehensive and balanced improvement in hardness, wear resistance, erosion resistance, thermal shock resistance, and hydration resistance. Its core advantage lies in precisely matching the demanding operating conditions of high-temperature industrial kilns. It leverages the high hardness and wear resistance of ceramic materials while relying on the strong resistance to alkaline slag erosion of magnesium-based materials. Furthermore, by developing modified intermediates and composite additives, it solves key technical challenges such as interfacial compatibility and hydration degradation. Ultimately, it yields long-life, high-efficiency, and stable composite refractory bricks, extending the service life of high-temperature kilns, reducing operation and maintenance costs, and ensuring the continuity and safety of industrial production.

[0027] II. This invention utilizes tabular corundum particles, micron-sized alumina, and ZrO2@SiC whiskers to synthesize a ceramic composite material. The tabular corundum particles, with their high density and hardness, form the rigid framework of the refractory brick, providing fundamental mechanical support and a wear-resistant substrate. Their unique lamellar structure enhances the interlocking between particles, improving the overall structural stability of the brick. Micron-sized alumina with an α / γ phase microsphere structure serves as a filler phase, precisely filling the gaps between the tabular corundum and other particles, effectively reducing apparent porosity. Simultaneously, its high activity during sintering forms a stable solid solution or low-melting-point glass phase with surrounding components, promoting particle adhesion and further enhancing the material's density and mechanical strength. The core-shell structure of ZrO2@SiC whiskers is a key component for improving the overall performance of the material. SiC whiskers possess extremely high tensile strength and thermal conductivity, rapidly conducting thermal stress generated by temperature fluctuations and reducing crack initiation caused by thermal stress concentration. The ZrO2 shell, stabilized by yttrium hexahydrate, forms a stable tetragonal phase. Upon temperature changes, it undergoes a martensitic transformation, resulting in volume expansion. This phase transformation toughening effect dissipates fracture energy and inhibits crack propagation. Simultaneously, the ZrO2 shell exhibits excellent chemical stability, effectively blocking the erosion of SiC whiskers by high-temperature alkaline media and preventing oxidation failure, thus achieving both toughening and protection functions. The ZrO2 shell's extremely strong chemical stability prevents molten K2CO3 from contacting the internal matrix, while the whiskers inhibit erosion crack propagation. The high density of the tabular corundum also slows down the penetration of alkaline media. Furthermore, micron-sized alumina acts as a densification core, filling intergranular gaps, reducing apparent porosity, increasing density, and inhibiting the penetration of alkaline media.

[0028] Third, the solid solution formed by fused magnesium chromium powder and fused magnesium sand not only improves the high-temperature strength of the material, but also optimizes the microstructure of the magnesium phase through Cr2O3 doping, reduces the grain growth rate, enhances the material's resistance to molten slag wetting, and delays molten slag penetration.

[0029] IV. In the boron-nitrogen-doped carbon-silane modified magnesium-aluminum spinel intermediate of the present invention, the boron-nitrogen-doped carbon black is prepared by high-temperature sintering of carbon black, boric acid, melamine and urea. Its BNC active groups form a dense coating layer, physically blocking the contact between moisture in the air and the magnesium components, fundamentally inhibiting the brick powdering and strength reduction problems caused by MgO hydration and the formation of magnesium hydroxide, significantly improving the material's storage, transportation and use stability. The silane coupling agent KH-560 acts as an interface modifier, its molecules chemically reacting with the hydroxyl groups on the surface of the magnesium-aluminum spinel, the active groups of the ceramic phase and the magnesium-based phase, forming chemical bonds, optimizing the interfacial bonding state between the intermediate and the matrix, reducing interfacial defects such as voids and microcracks, and improving the overall mechanical properties and corrosion resistance of the material. The magnesium-aluminum spinel itself possesses high chemical stability and high-temperature strength, and has good compatibility with the ceramic phase and the magnesium-based phase. As a transition phase, it coordinates the difference in thermal expansion coefficients between the two phases, further improving thermal shock resistance.

[0030] V. In the ferrosilicon-boron nitride composite additive, ferrosilicon alloy powder (FeSi75) reacts with surrounding components at high temperatures to form a low-melting-point glassy phase, filling the micropores generated during sintering and promoting material densification. The lamellar structure of hexagonal boron nitride forms a lubricating layer on the brick surface, reducing the friction between high-speed abrasives and the brick surface. Simultaneously, the chemical inertness of hexagonal boron nitride enhances the material's resistance to acid and alkali media. PEG2000 plays a dispersing role during preparation, ensuring uniform mixing of ferrosilicon powder and boron nitride powder and avoiding performance fluctuations caused by local agglomeration. Silica micropowder, as an auxiliary sintering agent, lowers the sintering temperature and promotes crystal phase development due to its high activity. Simultaneously, the magnesium silicate phase formed with the magnesium-based phase enhances the bonding strength between particles.

[0031] VI. The four-stage particle size distribution of fused magnesia and the three-stage particle size distribution of tabular corundum achieves the compact packing of raw material particles through a coarse particle skeleton, medium particle filling and fine particle density packing mode, thereby minimizing apparent porosity and improving material density and mechanical strength.

[0032] VII. The material conditioning step ensures that the alumina sol and all raw material particles are fully wetted, with uniform moisture distribution, reducing internal stress in the formed brick blank. Multi-stage sintering process: Drying thoroughly removes free and adsorbed water from the blank, preventing cracks caused by rapid moisture evaporation during drying; sintering at 500℃~600℃ achieves full carbonization of the thermosetting phenolic resin, forming a stable carbon bond network; sintering at 900℃~1000℃ promotes the formation of low-melting-point phases and initial bonding between particles; sintering at 1450℃~1550℃ ensures complete crystallization of the ZrO2 shell and sufficient reaction between components to form a stable crystalline phase. Simultaneously, a nitrogen protective atmosphere prevents oxidation and failure of SiC whiskers and the carbon phase, ensuring the structural and performance stability of each functional phase.

[0033] In summary, the core innovation of this invention lies in the precise matching and synergistic effect of each component and process parameter, rather than the performance superposition of a single component: the rigid framework and toughening and thermal conductivity of the ceramic phase complement the strong alkali erosion resistance of the magnesium-based phase, resolving the inherent contradiction of poor alkali resistance in traditional ceramic tiles and weak wear resistance in magnesia tiles. The boron-nitrogen-doped carbon-silane modified magnesium-aluminum spinel intermediate simultaneously achieves both waterproofing and interface optimization, solving the hydration problem of magnesia materials and building a bridge for the synergistic effect between the ceramic and magnesium-based phases, avoiding performance degradation due to poor compatibility between the two phases. The composite additives, particle size distribution, molding process, and sintering regime create a synergistic effect. The densification, lubrication, and wear resistance of the ferrosilicon-boron nitride composite additives, the enhanced wear resistance of zirconium diboride, the assisted sintering of silica powder, combined with the crystal phase development regulation of multi-stage sintering and the density improvement of high-pressure molding, through a chain reaction of densification, interface strengthening, and functional complementarity, simultaneously optimize the material's density, mechanical strength, erosion resistance, and thermal shock resistance. The phase transformation toughening and thermal protection of ZrO2@SiC whiskers, the waterproofing and interface lubrication of boron-nitrogen doped carbon black, and the wear-resistant lubrication of boron nitride work synergistically to improve the thermal shock resistance of the material and significantly enhance its resistance to erosion and wear, ensuring long-term stable service under harsh conditions of high temperature, severe temperature fluctuations, and high-speed erosion. Detailed Implementation

[0034] The present invention will be further described below with reference to specific implementation examples, but the present invention is not limited to these embodiments.

[0035] Example 1

[0036] An erosion-resistant ceramic-magnesium composite refractory brick comprises, by weight, the following raw materials: 35 parts ceramic composite material, 43 parts fused magnesia, 9 parts boron-nitrogen-doped carbon-silane modified magnesium-aluminum spinel intermediate, 10 parts fused magnesia-chromium powder, 4 parts zirconium diboride, 5 parts silica powder, 6.5 parts ferrosilicon-boron nitride composite additive, 4 parts thermosetting phenolic resin powder, 0.45 parts composite dispersant, and 12 parts alumina sol.

[0037] The ceramic composite material comprises tabular corundum particles, micron-sized alumina, and ZrO2@SiC whiskers in a mass ratio of 32:21:13. The composite dispersant comprises sodium hexametaphosphate and citric acid in a mass ratio of 0.9:1.

[0038] The particle size distribution of the fused magnesia is as follows: 35 wt% for particles smaller than 3 mm and ≤ 5 mm, 40 wt% for particles smaller than 1 mm and ≤ 3 mm, 15 wt% for particles smaller than 0.088 mm and ≤ 1 mm, and 10 wt% for particles smaller than 0.088 mm. The particle size distribution of the tabular corundum particles is as follows: 50 wt% for particles smaller than 1 mm and ≤ 3 mm, 42 wt% for particles smaller than 0.1 mm and 8 wt% for particles smaller than 0.1 mm.

[0039] The preparation method of ZrO2@SiC whiskers includes the following steps: Solution A is prepared by mixing 12 parts by mass of zirconium oxychloride octahydrate (ZrOCl2·8H2O), 1 part by mass of yttrium nitrate hexahydrate (Y(NO3)3·6H2O), and 50 parts by mass of deionized water; Solution B is prepared by mixing 2 parts by mass of PEG600 and 40 parts by mass of ethanol; Solution A and Solution B are mixed and stirred evenly at below 25℃; 1.1 mol / L dilute hydrochloric acid is added dropwise to adjust the pH to 2.8; the mixture is allowed to stand for 12 minutes; and 4 parts by mass of ortho-silicon are added dropwise at a rate of 1 drop / second while stirring at 350 rpm. TEOS (tetraethyl ether) was stirred for 35 min to obtain zirconium-silica sol. 55 parts of SiC whiskers were dispersed in 110 parts of ethanol to obtain a suspension. The suspension was added to the zirconium-silica sol under stirring at 450 rpm. The mixture was stirred continuously at 65℃ to 70℃ for 50 min, evaporated at 80℃ to 85℃ for 2.5 h, dried at 150℃ for 2.5 h, sintered at 580℃ for 2 h at a rate of 5℃ / min, and sintered at 1150℃ for 3.5 h at a rate of 7℃ / min. After cooling, the mixture was pulverized through a 325-mesh sieve to obtain ZrO2@SiC whiskers.

[0040] The preparation method of boron-nitrogen-doped carbon-silane modified magnesium-aluminum spinel intermediate includes the following steps: 2 parts by mass of PEG400 are added to 320 parts of isopropanol, stirred at 550 rpm for 12 min in the range of 50℃ to 55℃, 22 parts of boron-nitrogen-doped carbon black are added, stirred and dispersed evenly, 9 wt% glacial acetic acid aqueous solution is added dropwise to adjust the pH to 4.2, 95 parts of fused magnesium-aluminum spinel micro powder are added, stirred evenly in the range of 70℃ to 75℃, and vacuum distilled to remove all isopropanol to obtain pre-coated spinel; 3 parts of KH-560 silane coupling agent are dissolved in 35 parts of ethanol, then mixed evenly with the pre-coated spinel, evaporated and dried at 110℃ for 2.5 h, sintered at 320℃ for 2 h under nitrogen protection at a rate of 4℃ / min, cooled, and pulverized through a 250-mesh sieve to obtain boron-nitrogen-doped carbon-silane modified magnesium-aluminum spinel intermediate.

[0041] The preparation method of boron-nitrogen-doped carbon black includes the following steps: 18 parts by mass of carbon black, 1.5 parts by boric acid, 2.5 parts by mass of melamine and 0.6 parts by mass of urea are added to 60 parts by mass of ethanol and stirred and dispersed evenly in the range of 25℃ to 30℃ to obtain a suspension; the ethanol is removed by vacuum evaporation in the range of 65℃ to 75℃, dried at 110℃ for 7 hours, and ground through a 200-mesh sieve to obtain a precursor powder; under nitrogen protection, the temperature is raised to 880℃ at 5℃ / min and sintered for 2.5 hours, cooled, and pulverized through a 540-mesh sieve to obtain boron-nitrogen-doped carbon black.

[0042] The preparation method of the ferrosilicon-boron nitride composite additive includes the following steps: 73 parts by mass of ferrosilicon alloy powder (FeSi75), 28 parts by mass of boron nitride powder (h-BN), and 4 parts by mass of PEG2000 are mixed, ball-milled for 2.5 h (ball-to-material ratio 5.5:1), dried at 90 °C for 1.5 h under nitrogen protection, and passed through a 150-mesh sieve to obtain the ferrosilicon-boron nitride composite additive.

[0043] The preparation method of the above-mentioned erosion-resistant ceramic-magnesium composite refractory brick includes the following steps:

[0044] S1: According to the formula by mass parts, ceramic composite material, fused magnesia, fused magnesia-chromium powder, zirconium diboride, silica powder, ferrosilicon-boron nitride composite additive, thermosetting phenolic resin powder and composite dispersant are mixed until the color is uniform. Then, boron-nitrogen doped carbon-silane modified magnesium-aluminum spinel intermediate is added and mixed evenly. Then, aluminum sol is added and mixed until a plastic slurry without dry powder and lumps is formed. The slurry is then allowed to stand for 25 hours in the range of 20℃~25℃ and 60%~70%RH. After that, it is put into a mold and machine-pressed at a pressure of 135MPa for 45s to form a brick blank.

[0045] S2: Dry the brick blank at 110℃ for 36 hours, place it in a sintering furnace, and under nitrogen protection, heat it to 550℃ at 4℃ / min for 1.5 hours, continue to heat it to 950℃ for 1.5 hours, continue to heat it to 1500℃ for 3.5 hours, and then cool it to obtain refractory bricks.

[0046] Example 2

[0047] An erosion-resistant ceramic-magnesium composite refractory brick comprises, by weight, the following raw materials: 30 parts ceramic composite material, 45 parts fused magnesia, 8 parts boron-nitrogen-doped carbon-silane modified magnesium-aluminum spinel intermediate, 12 parts fused magnesia-chromium powder, 3 parts zirconium diboride, 6 parts silica powder, 5 parts ferrosilicon-boron nitride composite additive, 4.5 parts thermosetting phenolic resin powder, 0.3 parts composite dispersant, and 14 parts alumina sol.

[0048] The ceramic composite material comprises plate-shaped corundum particles, micron-sized alumina, and ZrO2@SiC whiskers in a mass ratio of 30:22:12. The composite dispersant comprises sodium hexametaphosphate and citric acid in a mass ratio of 1:1.

[0049] The particle size distribution of the fused magnesia is as follows: 45 wt% for particles smaller than 3 mm and less than 5 mm, 30 wt% for particles smaller than 1 mm and less than 3 mm, 15 wt% for particles smaller than 0.088 mm and less than 1 mm, and 10 wt% for particles smaller than 0.088 mm. The particle size distribution of the tabular corundum particles is as follows: 40 wt% for particles smaller than 1 mm and less than 3 mm, 55 wt% for particles smaller than 0.1 mm and less than 0.1 mm, and 5 wt% for particles smaller than 0.1 mm.

[0050] The preparation method of ZrO2@SiC whiskers includes the following steps: Solution A is prepared by mixing 10 parts by mass of zirconium oxychloride octahydrate (ZrOCl2·8H2O), 1.2 parts by mass of yttrium nitrate hexahydrate (Y(NO3)3·6H2O), and 40 parts by mass of deionized water; Solution B is prepared by mixing 2.5 parts by mass of PEG600 and 30 parts by mass of ethanol; Solution A and Solution B are mixed and ultrasonically dispersed at below 25℃; 1.2 mol / L dilute hydrochloric acid is added dropwise to adjust the pH to 2.5; the mixture is allowed to stand for 15 minutes; and then, under stirring at 300 rpm, 2 drops / second is added dropwise. Three parts of tetraethyl orthosilicate (TEOS) were stirred for 40 min to obtain zirconium-silica sol; 50 parts of SiC whiskers were dispersed in 120 parts of ethanol to obtain a suspension; the suspension was added to the zirconium-silica sol under stirring at 400 rpm, and stirred continuously at 65℃~70℃ for 60 min, evaporated at 80℃~85℃ for 2 h, dried at 155℃ for 2 h, sintered at 550℃ for 2.5 h by increasing the temperature at 6℃ / min, sintered at 1200℃ for 3 h by increasing the temperature at 6℃ / min, cooled, and pulverized through a 400-mesh sieve to obtain ZrO2@SiC whiskers.

[0051] The preparation method of boron-nitrogen-doped carbon-silane modified magnesium-aluminum spinel intermediate includes the following steps: 1.5 parts by mass of PEG400 are added to 350 parts of isopropanol and stirred at 500 rpm for 15 min in the range of 50℃ to 55℃. 18 parts of boron-nitrogen-doped carbon black are added and ultrasonically dispersed evenly. 10 wt% glacial acetic acid aqueous solution is added dropwise to adjust the pH to 4.0. 100 parts of fused magnesium-aluminum spinel micro powder are added and stirred evenly in the range of 70℃ to 75℃. The mixture is then distilled under reduced pressure to remove all isopropanol, resulting in pre-coated spinel. 2 parts of KH-560 silane coupling agent are dissolved in 40 parts of ethanol and then mixed evenly with the pre-coated spinel. The mixture is evaporated and dried at 100℃ for 3 h. Under nitrogen protection, the mixture is heated to 350℃ at 3℃ / min and sintered for 1.5 h. After cooling, the mixture is pulverized through a 325-mesh sieve to obtain the boron-nitrogen-doped carbon-silane modified magnesium-aluminum spinel intermediate.

[0052] The preparation method of boron-nitrogen-doped carbon black includes the following steps: by mass, 20 parts of carbon black, 1 part of boric acid, 3 parts of melamine and 0.5 parts of urea are added to 70 parts of ethanol and ultrasonically dispersed evenly in the range of 25℃ to 30℃ to obtain a suspension; the ethanol is removed by vacuum evaporation in the range of 65℃ to 75℃, dried at 100℃ for 8 hours, and ground through a 200-mesh sieve to obtain a precursor powder; under nitrogen protection, the temperature is raised to 850℃ at 6℃ / min and sintered for 3 hours, cooled, and pulverized through a 540-mesh sieve to obtain boron-nitrogen-doped carbon black.

[0053] The preparation method of the ferrosilicon-boron nitride composite additive includes the following steps: 70 parts by mass of ferrosilicon alloy powder (FeSi75), 30 parts by mass of boron nitride powder (h-BN), and 3 parts by mass of PEG2000 are mixed, ball-milled for 3 hours (ball-to-material ratio 5:1), dried at 100°C for 1 hour under nitrogen protection, and passed through a 200-mesh sieve to obtain the ferrosilicon-boron nitride composite additive.

[0054] The preparation method of the above-mentioned erosion-resistant ceramic-magnesium composite refractory brick includes the following steps:

[0055] S1: According to the formula by mass parts, ceramic composite material, fused magnesia, fused magnesia-chromium powder, zirconium diboride, silica powder, ferrosilicon-boron nitride composite additive, thermosetting phenolic resin powder and composite dispersant are mixed until the color is uniform. Then, boron-nitrogen doped carbon-silane modified magnesium-aluminum spinel intermediate is added and mixed evenly. Then, aluminum sol is added and mixed until a plastic mud without dry powder and lumps is formed. The mixture is then allowed to stand for 24 hours in the range of 20℃~25℃ and 60%~70%RH. After that, it is put into a mold and machine-pressed at a pressure of 150MPa for 30s to form a brick blank.

[0056] S2: Dry the brick blank at 115℃ for 24 hours, place it in a sintering furnace, and under nitrogen protection, heat it to 500℃ at 5℃ / min for 2 hours, continue to heat it to 900℃ for 2 hours, continue to heat it to 1450℃ for 4 hours, and then cool it to obtain refractory bricks.

[0057] Example 3

[0058] An erosion-resistant ceramic-magnesium composite refractory brick comprises, by weight, the following raw materials: 40 parts ceramic composite material, 40 parts fused magnesia, 10 parts boron-nitrogen-doped carbon-silane modified magnesium-aluminum spinel intermediate, 8 parts fused magnesia-chromium powder, 5 parts zirconium diboride, 4 parts silica powder, 8 parts ferrosilicon-boron nitride composite additive, 3.5 parts thermosetting phenolic resin powder, 0.6 parts composite dispersant, and 10 parts alumina sol.

[0059] The ceramic composite material comprises tabular corundum particles, micron-sized alumina, and ZrO2@SiC whiskers in a mass ratio of 35:20:15. The composite dispersant comprises sodium hexametaphosphate and citric acid in a mass ratio of 0.8:1.

[0060] The particle size distribution of the fused magnesia is as follows: 35 wt% for particles smaller than 3 mm and ≤ 5 mm, 40 wt% for particles smaller than 1 mm and ≤ 3 mm, 20 wt% for particles smaller than 0.088 mm and ≤ 1 mm, and 5 wt% for particles smaller than 0.088 mm. The particle size distribution of the tabular corundum particles is as follows: 45 wt% for particles smaller than 1 mm and ≤ 3 mm, 48 wt% for particles smaller than 0.1 mm and 7 wt% for particles smaller than 0.1 mm.

[0061] The preparation method of ZrO2@SiC whiskers includes the following steps: Solution A is prepared by mixing 15 parts by mass of zirconium oxychloride octahydrate (ZrOCl2·8H2O), 0.8 parts by mass of yttrium nitrate hexahydrate (Y(NO3)3·6H2O), and 60 parts by mass of deionized water; Solution B is prepared by mixing 1.5 parts by mass of PEG600 and 50 parts by mass of ethanol; Solution A and Solution B are mixed and stirred evenly at below 25℃; 1 mol / L dilute hydrochloric acid is added dropwise to adjust the pH to 3.0; the mixture is allowed to stand for 10 min; and 5 mol / L dilute hydrochloric acid is added dropwise at a rate of 1 drop / second while stirring at 400 rpm. One part of tetraethyl orthosilicate (TEOS) was stirred for 30 min to obtain zirconium-silica sol; 60 parts of SiC whiskers were dispersed in 100 parts of ethanol to obtain a suspension; the suspension was added to the zirconium-silica sol under stirring at 500 rpm, and stirred continuously at 65℃~70℃ for 40 min, evaporated at 80℃~85℃ for 3 h, dried at 145℃ for 3 h, sintered at 600℃ for 1.5 h by heating at 4℃ / min, sintered at 1100℃ for 4 h by heating at 8℃ / min, cooled, and pulverized through a 325 mesh sieve to obtain ZrO2@SiC whiskers.

[0062] The preparation method of boron-nitrogen-doped carbon-silane modified magnesium-aluminum spinel intermediate includes the following steps: 2.5 parts by mass of PEG400 are added to 300 parts of isopropanol, stirred at 600 rpm for 10 min in the range of 50℃ to 55℃, 25 parts of boron-nitrogen-doped carbon black are added, stirred and dispersed evenly, 8 wt% glacial acetic acid aqueous solution is added dropwise to adjust the pH to 4.5, 90 parts of fused magnesium-aluminum spinel micro powder are added, stirred evenly in the range of 70℃ to 75℃, and vacuum distilled to remove all isopropanol to obtain pre-coated spinel; 4 parts of KH-560 silane coupling agent are dissolved in 30 parts of ethanol, and then mixed evenly with the pre-coated spinel, evaporated and dried at 120℃ for 2 h, sintered at 300℃ for 2.5 h under nitrogen protection at a rate of 5℃ / min, cooled, and pulverized through a 250-mesh sieve to obtain boron-nitrogen-doped carbon-silane modified magnesium-aluminum spinel intermediate.

[0063] The preparation method of boron-nitrogen-doped carbon black includes the following steps: by mass, 15 parts carbon black, 2 parts boric acid, 2 parts melamine and 0.8 parts urea are added to 50 parts ethanol, and stirred and dispersed evenly in the range of 25℃ to 30℃ to obtain a suspension; the ethanol is removed by vacuum evaporation in the range of 65℃ to 75℃, dried at 120℃ for 6 hours, and ground through a 250-mesh sieve to obtain a precursor powder; under nitrogen protection, the temperature is raised to 900℃ at 4℃ / min and sintered for 2 hours, cooled, and pulverized through a 650-mesh sieve to obtain boron-nitrogen-doped carbon black.

[0064] The preparation method of the ferrosilicon-boron nitride composite additive includes the following steps: 75 parts by mass of ferrosilicon alloy powder (FeSi75), 25 parts by mass of boron nitride powder (h-BN), and 5 parts by mass of PEG2000 are mixed, ball-milled for 2 hours (ball-to-material ratio 6:1), dried at 80°C for 2 hours under nitrogen protection, and passed through a 150-mesh sieve to obtain the ferrosilicon-boron nitride composite additive.

[0065] The preparation method of the above-mentioned erosion-resistant ceramic-magnesium composite refractory brick includes the following steps:

[0066] S1: According to the formula by mass parts, ceramic composite material, fused magnesia, fused magnesia-chromium powder, zirconium diboride, silica powder, ferrosilicon-boron nitride composite additive, thermosetting phenolic resin powder and composite dispersant are mixed until the color is uniform. Then, boron-nitrogen doped carbon-silane modified magnesium-aluminum spinel intermediate is added and mixed evenly. Then, aluminum sol is added and mixed until a plastic slurry without dry powder and lumps is formed. The slurry is then allowed to stand for 26 hours in the range of 20℃~25℃ and 60%~70%RH. After that, it is put into a mold and machine-pressed at a pressure of 120MPa for 60s to form a brick blank.

[0067] S2: Dry the brick blank at 105℃ for 48 hours, place it in a sintering furnace, and under nitrogen protection, heat it to 600℃ at 3℃ / min and sinter for 1.5 hours, continue to heat it to 1000℃ and sinter for 1.5 hours, continue to heat it to 1550℃ and sinter for 3 hours, and then cool it to obtain refractory bricks.

[0068] The raw material specifications and sources involved in the above embodiments are as follows: The tabular corundum is from Zibo Dongda Environmental Protection Technology Co., Ltd. The micron-sized alumina is from Yumu (Ningbo) New Materials Co., Ltd., consisting of α / γ phase microspheres with a median particle size of 1μm to 5μm. The purity of zirconium oxychloride octahydrate (ZrOCl2·8H2O) is above 98%. The purity of yttrium nitrate hexahydrate (Y(NO3)3·6H2O) is above 98%. PEG600 is polyethylene glycol with a number average molecular weight of 600, sourced from Nanjing Kerunjiang Chemical Co., Ltd. The purity of tetraethyl orthosilicate (TEOS) is above 99%. SiC whiskers are from Guangzhou Hongwu Materials Technology Co., Ltd., with a diameter of 0.1μm-2.5μm and a length of 10μm-50μm. The fused magnesia has an MgO content of above 97%. PEG400 is polyethylene glycol with a number average molecular weight of 400, sourced from Nanjing Kerunjiang Chemical Co., Ltd. The purity of isopropanol is above 99%. Carbon black is sourced from Shenyang Elepx Chemical Co., Ltd., with a particle size below 500μm. The purity of boric acid is above 99%. The purity of melamine is above 99%. The purity of urea is above 98%. Fused magnesium aluminum spinel is sourced from Zhengzhou Yufa High-Tech Materials Co., Ltd., with an Al2O3 content above 70% and an MgO content above 20%, pulverized into micro-powder passing through a 325-mesh sieve. KH-560 silane coupling agent is sourced from Wuhan Kanos Technology Co., Ltd., with a purity of 99%. Fused magnesium chromium powder has a Cr2O3 content above 30%, an MgO content above 42%, and a median particle size below 1μm. Zirconium diboride (ZrB2) has a purity ≥99% and a median particle size of 1μm~5μm. Silica micropowder has a SiO2 content ≥98% and a particle size passing through a 200-mesh sieve. Ferrosilicon alloy powder (FeSi75) is sourced from Hebei Yuehan Metal Materials Sales Co., Ltd., with a particle size passing through a 200-mesh sieve. Boron nitride powder (h-BN) is hexagonal boron nitride with a median particle size of 3μm to 8μm. PEG2000 is polyethylene glycol with a number average molecular weight of 2000, sourced from Nanjing Kerunjiang Chemical Co., Ltd. Thermosetting phenolic resin powder is sourced from Wuhan Jiyesheng Chemical Co., Ltd., with a particle size passing through a 200-mesh sieve. Sodium hexametaphosphate has a purity of over 99%. Citric acid has a purity of over 99%. Aluminum sol is sourced from Yangzhou Zhongtianli New Materials Co., Ltd., with a solid content of 25%.

[0069] Comparative Example 1

[0070] The difference from Example 1 is that the ceramic composite material is changed to 10 parts and the fused magnesia is changed to 68 parts.

[0071] Comparative Example 2

[0072] The difference from Example 1 is that no boron-nitrogen-doped carbon-silane modified magnesium-aluminum spinel intermediate is added.

[0073] Comparative Example 3

[0074] The difference from Example 1 is that the amount of ferrosilicon-boron nitride composite additive is changed to 1.5 parts, and the amount of silicon micro powder is changed to 10 parts.

[0075] Comparative Example 4

[0076] The difference from Example 1 is that the ceramic composite material is replaced with plate-shaped corundum particles (without adding micron-sized alumina and ZrO2@SiC whiskers).

[0077] Comparative Example 5

[0078] The difference from Example 1 is that ZrO2@SiC whiskers are directly replaced by SiC whiskers.

[0079] Comparative Example 6

[0080] The difference from Example 1 is that yttrium nitrate hexahydrate and PEG600 are not added in the preparation method of ZrO2@SiC whiskers.

[0081] Comparative Example 7

[0082] The difference from Example 1 is that the step of "sintering at 1150°C for 3.5 hours with a heating rate of 7°C / min" is omitted in the preparation method of ZrO2@SiC whiskers.

[0083] Comparative Example 8

[0084] The difference from Example 1 is that the boron-nitrogen doped carbon-silane modified magnesium-aluminum spinel intermediate is directly replaced by fused magnesium-aluminum spinel micro powder (micro powder that has passed through a 325-mesh sieve).

[0085] Comparative Example 9

[0086] The difference from Example 1 is that in the preparation method of boron-nitrogen doped carbon-silane modified magnesium-aluminum spinel intermediate, the amount of boron-nitrogen doped carbon black added is 5 parts.

[0087] Comparative Example 10

[0088] The difference from Example 1 is that in the preparation method of boron nitrogen doped carbon-silane modified magnesium aluminum spinel intermediate, PEG400 is not added and the step of "sintering at 320°C for 2 hours under nitrogen protection at a rate of 4°C / min, cooling, and pulverizing through a 250-mesh sieve" is omitted.

[0089] I. Bulk density and apparent porosity:

[0090] Sample: 50mm×50mm×50mm cube, 5 parallel samples.

[0091] Testing: The sample was dried at 110℃ for 24 hours to constant weight, and after cooling, the dried mass m1 was measured. The sample was immersed in molten paraffin at 60℃ for 1 minute, and after cooling, the mass after sealing with paraffin was measured m2. The sealed sample was suspended in water at 20℃, and the suspended mass m3 was measured. Bulk density ρ (g / cm³) 3 ) = m1 / (m2-m3), ρwater = 1g / cm³ 3 Apparent porosity P(%) = [(m2-m1) / (m2-m3)] × 100%.

[0092] II. Compressive strength at room temperature:

[0093] Sample: 40mm×40mm×40mm cube, 5 parallel samples.

[0094] Testing: The specimen was dried at 110℃ for 24 hours, and after cooling, the area S of the pressure-bearing surface was measured. On a universal testing machine, it was loaded at a rate of 0.5 MPa / s until failure, and the maximum load F was recorded. Compressive strength R = F / S.

[0095] III. Flexural strength at 1400℃:

[0096] Sample: 25mm×25mm×120mm cuboid, 5 parallel samples.

[0097] Testing: The specimen was dried at 110℃ for 24 hours, and after cooling, the width b and height h at the middle of the specimen were measured. Under a nitrogen atmosphere with a flow rate of 1.5 L / min, the temperature was increased to 1400℃ at a rate of 5℃ / min and held for 30 minutes. Using the three-point bending method, with a support span of 100 mm, a load was applied at 0.5 mm / min until fracture, and the fracture load F was recorded. b Flexural strength R b =(3×F b ×L) / (2×b×h 2 ), L=100mm.

[0098] IV. Thermal shock resistance at 1100℃ (water quenching method):

[0099] Sample: 230mm×114mm×65mm cuboid, 3 parallel samples.

[0100] Test: The sample was dried at 110℃ for 24 hours and then cooled. The temperature was increased to 1100℃ at a rate of 10℃ / min and held for 30 minutes. The sample was then quickly removed and immersed in 20℃ water for 5 minutes to rapidly cool it to 1 / 3 of its height. After removal, the sample was dried in air for 5 minutes. The heating-rapid cooling cycle was repeated until the sample broke, and the number of cycles was recorded.

[0101] V. Slag erosion resistance at 1650℃ (static crucible method):

[0102] Samples: cut into crucible-shaped samples with an outer diameter of 50 mm, an inner diameter of 20 mm, and a height of 50 mm, with 3 parallel samples.

[0103] Testing: Weigh 20.0g of basic converter slag powder (containing 45wt% CaO, 15wt% SiO2, 20wt% Fe2O3, 8wt% MgO, and 5% Al2O3, sieved through a 180-mesh sieve), fill it into a crucible, and compact it. Under a nitrogen atmosphere, heat to 1650℃ at a rate of 5℃ / min and hold for 3 hours. After cooling with the furnace, cut it longitudinally and measure the maximum erosion layer depth (mm).

[0104] VI. Resistance to alkali corrosion at 1100℃:

[0105] Sample: 25mm×25mm×125mm cuboid, 3 parallel samples.

[0106] Testing: A groove (5 mm deep, 5 mm wide, and 50 mm long) was etched in the center of the sample surface, filled with K2CO3 powder, and covered. The sample was placed in an air atmosphere furnace and heated to 1100℃ at a rate of 3℃ / min, and held at that temperature for 5 hours. After cooling, the sample was longitudinally cut open, and the maximum erosion depth (mm) was measured.

[0107] VII. Resistance to erosion and abrasion at room temperature:

[0108] Sample: 50mm×50mm×20mm sheet, the scalded surface is polished to a roughness of Ra1.6μm or less, 5 parallel samples.

[0109] Test: Weigh the initial mass of the sample, m1. Mount the sample in the fixture, with the rinsing surface facing the nozzle, 50 mm away, at a 30° angle. Use 200-mesh Al2O3 abrasive, a flow rate of 150 g / min, nitrogen gas as the carrier, a pressure of 0.4 MPa, and rinse for 60 min. After the test, remove the residual abrasive and weigh the sample, m2. Mass loss rate W (%) = (m1 - m2) / m1 × 100%.

[0110] 8. Resistance to airflow erosion and abrasion at 1400℃:

[0111] Sample: 75mm×75mm×40mm square, with a 75mm×75mm polished scouring surface, 3 parallel samples.

[0112] Testing: Weigh the initial mass m1 of the sample. Heat to 1400℃ under a nitrogen atmosphere and hold for 1 hour. Use 80-mesh silicon carbide sand as the abrasive, with a flow rate of 150 g / min, nitrogen as the carrier, a pressure of 0.4 MPa, and vertical scouring at a distance of 25 mm for 10 minutes. After cooling, weigh the mass m2. Mass loss rate W (%) = (m1 - m2) / m1 × 100%.

[0113] IX. Resistance to hydration:

[0114] Sample: 50mm×50mm×50mm cube, 5 parallel samples.

[0115] Testing: The sample was dried at 110℃ for 24 hours to constant weight, and the initial mass m1 was measured. Deionized water was added to 1 / 3 of the sample height. The temperature was raised to 121℃ and the pressure was 0.1 MPa, and maintained for 24 hours. After removal, the sample was dried at 110℃ to constant weight, and the mass m2 was measured. Hydration weight gain rate Wh (%) = (m2 - m1) / m1 × 100%.

[0116] Table 1. Test Results (Average Values)

[0117]

[0118] The results of the above embodiments show that: Examples 1 to 3 have good performance: in the ceramic composite, the tabular corundum forms a rigid skeleton, and the micron-sized alumina fills the gaps, reducing apparent porosity and increasing density; the core-shell structure of ZrO2@SiC whiskers plays a dual role: the high thermal conductivity of SiC whiskers quickly dissipates heat dissipation stress, and the phase transformation toughening effect of the ZrO2 shell consumes fracture energy by generating microcracks, simultaneously improving thermal shock resistance and mechanical strength. The magnesium-based phase provides strong resistance to alkaline slag erosion and forms a functional complement to the ceramic phase. The boron-nitrogen-doped carbon-silane modified magnesium-aluminum spinel intermediate blocks the contact between moisture and magnesium components through the boron-nitrogen-doped carbon black coating layer, inhibiting the hydration reaction; the silane coupling agent optimizes the interfacial bonding between the intermediate and the ceramic and magnesium-based phases, reduces interfacial defects, and improves the overall density and mechanical properties of the material; the high chemical stability of the magnesium-aluminum spinel itself further enhances the resistance to slag and alkaline erosion. In the ferrosilicon-boron nitride composite additive, ferrosilicon alloy powder generates a low-melting-point glassy phase at high temperatures, filling pores and promoting sintering densification; the lamellar structure of boron nitride forms a lubricating layer, reducing the friction between the abrasive and the brick surface, while its chemical inertness enhances erosion resistance. Reasonable particle size distribution achieves close particle packing, high-pressure molding reduces forming porosity, nitrogen atmosphere sintering avoids component oxidation, and a multi-stage heating regime ensures full carbonization and crystal development of the thermosetting phenolic resin, further optimizing the overall material performance.

[0119] The comparative results above show that when the component ratio is unbalanced and the proportion of ceramic composite is too low, there is a lack of sufficient hard reinforcing phase to support the skeleton, resulting in decreased density, increased apparent porosity, and a significant reduction in thermal shock resistance, wear resistance, and high-temperature strength. Omitting the boron-nitrogen-doped carbon-silane modified magnesium-aluminum spinel intermediate worsens interfacial compatibility, intensifies hydration reactions, and comprehensively reduces thermal shock resistance, corrosion resistance, and mechanical properties. When only tabular corundum is retained in the ceramic composite, the lack of micron-sized alumina filling effect and the toughening and thermal conductivity of ZrO2@SiC whiskers increases material brittleness and significantly deteriorates thermal shock resistance and erosion resistance. Replacing ZrO2@SiC whiskers with SiC whiskers results in the loss of the phase transformation toughening and protective effect of the ZrO2 shell, making SiC whiskers susceptible to corrosion in high-temperature alkaline environments, thus reducing thermal shock resistance and corrosion resistance. When the high-temperature sintering step is omitted in the preparation of ZrO2@SiC whiskers, the ZrO2 shell is not fully crystallized and has a loose structure, which cannot effectively protect the SiC whiskers. Moreover, the bonding force with the matrix is ​​weak, resulting in a decrease in mechanical properties, thermal shock resistance, and erosion resistance. When the dispersant or sintering step is omitted in the preparation of boron-nitrogen-doped carbon-silane modified magnesium-aluminum spinel intermediates, the coating layer is uneven, the bonding force is weak, the interface defects increase, and the material density and overall performance deteriorate. When the amount of boron-nitrogen-doped carbon black added is insufficient, the coating layer is discontinuous, the waterproofing, interface enhancement, and lubrication effects are weakened, and all properties decrease to varying degrees. When excessive silicon micropowder replaces the silicon-iron-boron nitride composite additive, the high activity of silicon micropowder easily reacts with the magnesium-based phase at high temperatures to form a low-melting-point phase, resulting in a decrease in high-temperature strength. At the same time, the lack of lubrication from boron nitride deteriorates the resistance to erosion and slag corrosion. When yttrium nitrate is lacking in the preparation of ZrO2@SiC whiskers, ZrO2 cannot stabilize the tetragonal phase, and the phase transformation toughening effect fails. When PEG dispersant is lacking, the zirconium-silica sol is unevenly dispersed, the core-shell structure defects increase, and the toughening, wear resistance, and corrosion resistance are weakened.

Claims

1. An erosion-resistant ceramic-magnesium composite refractory brick, characterized in that, By weight, the following raw materials are included: 30-40 parts ceramic composite material, 40-45 parts fused magnesia, 8-10 parts boron-nitrogen doped carbon-silane modified magnesium-aluminum spinel intermediate, 8-12 parts fused magnesia-chromium powder, 3-5 parts zirconium diboride, 4-6 parts silica powder, 5-8 parts ferrosilicon-boron nitride composite additive, 3.5-4.5 parts thermosetting phenolic resin powder, 0.3-0.6 parts composite dispersant, and 10-14 parts aluminum sol. The boron-nitrogen-doped carbon-silane modified magnesium-aluminum spinel intermediate is prepared by dispersing PEG and boron-nitrogen-doped carbon black in isopropanol, adjusting the pH to 4.0-4.5, adding fused magnesium-aluminum spinel micro powder, dispersing and distilling to obtain pre-coated spinel, then mixing with silane coupling agent ethanol solution, drying, sintering at 300℃-350℃, and pulverizing. The mass ratio of PEG, boron-nitrogen-doped carbon black, fused magnesium-aluminum spinel micro powder and silane coupling agent is (1.5-2.5):(18-25):(90-100):(2-4). The boron-nitrogen-doped carbon black is prepared by dispersing carbon black, boric acid, melamine and urea in ethanol at a mass ratio of (15-20):(1-2):(2-3):(0.5-0.8), distilling, drying, grinding into precursor powder, sintering at 850℃-900℃, and pulverizing. The ceramic composite material comprises plate-shaped corundum particles, micron-sized alumina, and ZrO2@SiC whiskers in a mass ratio of (30-35):(20-22):(12-15); the ZrO2@SiC whiskers are prepared by mixing a solution A of zirconium oxychloride octahydrate, yttrium nitrate hexahydrate, and deionized water with a PEG ethanol solution, adjusting the pH to 2.5-3.0, adding tetraethyl orthosilicate to obtain zirconium-silica sol, then mixing it with an ethanol suspension of SiC whiskers, evaporating and drying the mixture, sintering it at 550℃-600℃ and 1100℃-1200℃ respectively, and then pulverizing it to prepare the composite material. The ferrosilicon-boron nitride composite additive is prepared by ball milling ferrosilicon alloy powder, boron nitride powder and PEG2000 in a mass ratio of (70-75):(25-30):(3-5). The composite dispersant comprises sodium hexametaphosphate and citric acid in a mass ratio of (0.8-1):

1.

2. The erosion-resistant ceramic-magnesium composite refractory brick according to claim 1, characterized in that, The particle size distribution of the fused magnesia is as follows: 3mm < particle size ≤ 5mm, accounting for 35wt% to 45wt%; 1mm < particle size ≤ 3mm, accounting for 30wt% to 40wt%; 0.088mm < particle size ≤ 1mm, accounting for 15wt% to 25wt%; and less than 0.088mm, accounting for 5wt% to 10wt%. The particle size distribution of the tabular corundum particles is as follows: 1mm < particle size ≤ 3mm, accounting for 40wt% to 50wt%; 0.1mm < particle size ≤ 1mm, accounting for 42wt% to 55wt%; and less than 0.1mm, accounting for 5wt% to 8wt%.

3. The erosion-resistant ceramic-magnesium composite refractory brick according to claim 1, characterized in that, The preparation method of the ZrO2@SiC whiskers includes the following steps: by mass, 10 to 15 parts of zirconium oxychloride octahydrate, 0.8 to 1.2 parts of yttrium nitrate hexahydrate and 40 to 60 parts of deionized water are used to prepare solution A; Solution B was prepared by mixing 1.5 to 2.5 parts PEG with 30 to 50 parts ethanol. Solution A and solution B were mixed and dispersed evenly, and the pH was adjusted to 2.5 to 3.

0. The mixture was allowed to stand, and 3 to 5 parts tetraethyl orthosilicate were added dropwise while stirring to obtain zirconium-silica sol. 50 to 60 parts SiC whiskers were dispersed in 100 to 120 parts ethanol to obtain a suspension. The suspension was added to the zirconium-silica sol while stirring, and the mixture was stirred, evaporated, dried, sintered at 550 to 600°C, sintered at 1100 to 1200°C, cooled, and pulverized to obtain ZrO2@SiC whiskers.

4. The erosion-resistant ceramic-magnesium composite refractory brick according to claim 3, characterized in that, The average molecular weight of the PEG is 600; the sintering time at 550℃ to 600℃ is 1.5h to 2.5h; the sintering time at 1100℃ to 1200℃ is 3h to 4h; and the particle size of the pulverized material is sieved through a 325-400 mesh sieve.

5. The erosion-resistant ceramic-magnesium composite refractory brick according to claim 1, characterized in that, The preparation method of the boron-nitrogen-doped carbon-silane modified magnesium-aluminum spinel intermediate includes the following steps: by mass, 1.5 to 2.5 parts of PEG are added to 300 to 350 parts of isopropanol and stirred; 18 to 25 parts of boron-nitrogen-doped carbon black are added and dispersed evenly; the pH is adjusted to 4.0 to 4.5; 90 to 100 parts of fused magnesium-aluminum spinel powder are added and stirred evenly; isopropanol is removed by distillation to obtain pre-coated spinel; 2 to 4 parts of silane coupling agent are dissolved in 30 to 40 parts of ethanol, and then mixed evenly with the pre-coated spinel; the mixture is evaporated and dried; under nitrogen protection, the mixture is heated to 300°C to 350°C for sintering; cooled; and pulverized to obtain the boron-nitrogen-doped carbon-silane modified magnesium-aluminum spinel intermediate.

6. The erosion-resistant ceramic-magnesium composite refractory brick according to claim 5, characterized in that, The average molecular weight of the PEG is 400; the median particle size of the fused magnesium aluminum spinel micro powder is 20μm to 30μm; the silane coupling agent is KH-560; the sintering time at 300℃ to 350℃ is 1.5h to 2.5h; and the particle size of the pulverized material is sieved through a 250-325 mesh sieve.

7. The erosion-resistant ceramic-magnesium composite refractory brick according to claim 5, characterized in that, The preparation method of the boron-nitrogen-doped carbon black includes the following steps: by mass, 15-20 parts of carbon black, 1-2 parts of boric acid, 2-3 parts of melamine and 0.5-0.8 parts of urea are added to 50-70 parts of ethanol and dispersed evenly. The ethanol is evaporated to remove the carbon black, dried, and ground through a 200-250 mesh sieve to obtain a precursor powder. Under nitrogen protection, the powder is heated to 850-900℃ and sintered for 2-3 hours. After cooling, the powder is pulverized through a 540-650 mesh sieve to obtain boron-nitrogen-doped carbon black.

8. The erosion-resistant ceramic-magnesium composite refractory brick according to claim 1, characterized in that, The preparation method of the ferrosilicon-boron nitride composite additive includes the following steps: by mass, 70 to 75 parts of ferrosilicon alloy powder, 25 to 30 parts of boron nitride powder, and 3 to 5 parts of PEG2000 are mixed, ball-milled, dried under nitrogen protection, and passed through a 150-200 mesh sieve to obtain the ferrosilicon-boron nitride composite additive.

9. The method for preparing an erosion-resistant ceramic-magnesium composite refractory brick according to claim 1, characterized in that, Includes the following steps: S1: According to the formula by mass parts, ceramic composite material, fused magnesia, fused magnesia-chromium powder, zirconium diboride, silicon micro powder, ferrosilicon-boron nitride composite additive, thermosetting phenolic resin powder and composite dispersant are mixed evenly. Then, boron-nitrogen doped carbon-silane modified magnesium-aluminum spinel intermediate is added and mixed evenly. Then, aluminum sol is added and mixed into plastic mud. The mixture is then pressed into shape by machine to obtain brick blank. S2: The brick blanks are dried, sintered, and cooled to obtain refractory bricks.

10. The method for preparing an erosion-resistant ceramic-magnesium composite refractory brick according to claim 9, characterized in that, In S1: the material is trapped at 20℃~25℃ and 60%~70%RH for 24h~26h; the pressure of the machine pressing is 120MPa~150MPa, and the holding time is 30s~60s; In S2: the drying is carried out at 105℃~115℃ for 24h~48h; the sintering is carried out by heating to 500℃~600℃ for 1.5h~2h, heating to 900℃~1000℃ for 1.5h~2h, and heating to 1450℃~1550℃ for 3h~4h.

Images