Anti-erosion ceramic composite magnesium-based refractory material and preparation method thereof

Abstract

The application provides an anti-erosion ceramic composite magnesium-based refractory material and a preparation method thereof, and belongs to the technical field of ceramic and magnesia refractory bricks. The refractory material comprises fused magnesia, composite ceramic powder, MCR reinforced aggregate, sintering aid, interface modifier, active reinforcing component and composite binder. The composite ceramic powder is prepared by sintering zirconium dioxide powder, urea, nano titanium powder, micron silicon powder, boric acid, carbon black, calcium fluoride and polyethylene glycol. The MCR reinforced aggregate is prepared by coating corundum particles with magnesium-aluminum sol, sintering, coating with slurry prepared from light-burned magnesia powder, polymethyl methacrylate and PVB ethanol solution, and sintering. The interface modifier is prepared by reacting aluminum triacetylacetone with acetylacetone to obtain a solution, and then reacting with a magnesium nitrate ethylene glycol monomethyl ether solution and deionized water. The components are designed in cooperation and the process is accurately controlled, so that the mechanical strength, high-temperature stability, erosion resistance and anti-erosion of the refractory material are balanced and optimized.

Description

Technical Field

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

[0002] In high-temperature industries such as metallurgy, building materials, and chemicals, the lining materials of core equipment such as furnaces, rotary kilns, and ladles directly determine the service life and production safety of the equipment. These linings must withstand multiple harsh conditions over a long period of time, including temperatures above 1500℃, high-speed erosion by molten metal and slag, chemical corrosion, and temperature fluctuations. Among these, erosion wear caused by high-speed fluids is one of the main causes of lining failure.

[0003] Magnesia-based refractory bricks have become the mainstream choice for high-temperature industrial linings due to their excellent high-temperature resistance, good resistance to slag erosion, and high-temperature structural stability. Their main component is magnesium oxide, which, thanks to its high melting point and strong chemical stability, effectively resists the erosion of molten slag. However, traditional magnesia-based refractory bricks have significant technical shortcomings: pure magnesium-based materials are brittle and lack toughness, making them prone to spalling and wear under the impact of high-speed molten materials; simultaneously, their high coefficient of thermal expansion makes them susceptible to thermal stress cracks during temperature fluctuations. The propagation of these cracks further exacerbates erosion, resulting in the service life of traditional magnesia-based refractory bricks failing to meet the demands of modern high-temperature industrial operations for high efficiency and large-scale production.

[0004] With the transformation of industrial production towards intensification and energy conservation, furnace operating temperatures have increased to over 1600℃, and the flow rate of molten materials has accelerated, significantly increasing the requirements for the erosion resistance of the lining. To compensate for the shortcomings of traditional magnesia-based refractory bricks, the industry has gradually carried out research on composite modification. Early modification approaches focused on optimizing the purity of magnesia raw materials, increasing the material density by selecting high-purity fused magnesia. However, while simply increasing density enhanced wear resistance, it further reduced thermal shock resistance, making cracking problems more prominent. Subsequently, ceramic composite technology became the core direction for the modification of magnesia-based refractory bricks. By introducing ceramic phase components such as alumina, silicon carbide, and silicon nitride into the magnesia matrix, the high hardness, high wear resistance, and low expansion coefficient of ceramic materials are utilized to construct composite structures. In addition, the binder system has also been upgraded from traditional clay bonding and water glass bonding to aluminum phosphate bonding and sol-gel bonding, strengthening the interfacial bonding strength between the ceramic phase and the magnesia matrix.

[0005] Although existing modified magnesia refractory bricks have improved in erosion resistance, technical bottlenecks remain: the thermal expansion of the ceramic phase components and the magnesia matrix is ​​mismatched, easily generating interfacial stress at high temperatures, leading to a decrease in material toughness; the composite system's thermal shock resistance and erosion resistance are difficult to balance, and improved wear resistance often comes at the cost of weakened thermal stability. Therefore, it is necessary to develop ceramic composite magnesia refractory bricks that possess both excellent erosion resistance and good thermal shock resistance. Summary of the Invention

[0006] To address the problems still existing in existing magnesia-based refractory brick technologies, such as mismatched thermal expansion between different materials, easy generation of interfacial stress at high temperatures, decreased material toughness, and difficulty in simultaneously achieving thermal shock resistance and erosion resistance, this invention provides an erosion-resistant ceramic composite magnesia-based refractory material and its preparation method. The refractory material is prepared by combining fused magnesia, composite ceramic powder, MCR reinforcing aggregate, sintering aid, interfacial modifier, active reinforcing component, and composite binder. Through component synergistic design and precise process control, a balanced optimization of mechanical strength, high-temperature stability, erosion resistance, and erosion resistance is achieved. The specific technical solution is as follows:

[0007] An erosion-resistant ceramic composite magnesium-based refractory material comprises the following raw materials in parts by weight: 58-62 parts fused magnesia, 5-8 parts composite ceramic powder, 5-7 parts MCR reinforcing aggregate, 1.5-2.5 parts sintering aid, 2.5-3.5 parts interface modifier, 9-14 parts active reinforcing component, and 5-7 parts composite binder;

[0008] The particle size distribution of the fused magnesia is as follows: 3mm < particle size ≤ 5mm, accounting for 20wt% to 25wt%; 1mm < particle size ≤ 3mm, accounting for 30wt% to 35wt%; 0.074mm < particle size ≤ 1mm, accounting for 30wt% to 35wt%; and particle size ≤ 0.074mm, accounting for 10wt% to 15wt%.

[0009] The composite ceramic powder is obtained by sintering zirconium dioxide powder and urea at 650℃~700℃ to obtain pre-nitrided ZrO2, which is then ball-milled with nano-titanium powder, micron-sized silica powder, boric acid, carbon black, calcium fluoride and polyethylene glycol in anhydrous ethanol to prepare precursor materials. The precursor materials are then sintered at 500℃~600℃, 1200℃~1300℃ and 1550℃~1650℃ in sequence, and then pulverized through a 2000-2500 mesh sieve. The mass ratio of the micron-sized silica powder, nano-titanium powder, zirconium dioxide powder, boric acid, urea, carbon black, calcium fluoride and polyethylene glycol is (28~32):(23~27):(18~22):(5~7):(8~12):(10~14):(1~2):(0.4~0.6).

[0010] The MCR-reinforced aggregate is prepared by coating corundum particles with a sol, sintering them sequentially at 500℃~550℃ and 1250℃~1350℃ to obtain a primary coating material, followed by coating with a slurry, and sintering them sequentially at 500℃~550℃ and 1550℃~1650℃. The sol is prepared from Mg(NO3)2·6H2O, Al(NO3)3·9H2O and citric acid. The slurry is prepared from lightly calcined magnesium oxide powder, polymethyl methacrylate and PVB ethanol solution. The particle size range of the MCR-reinforced aggregate is 0.3mm~2.2mm.

[0011] The interface modifier is a magnesium aluminum spinel precursor sol, which is prepared by reacting aluminum triacetylacetonate with acetylacetonate in anhydrous ethanol to obtain solution A, dissolving Mg(NO3)2·6H2O in ethylene glycol monomethyl ether to obtain solution B, mixing solution A and solution B, adding deionized water to react, and concentrating to a solid content of 20wt% to 25wt%.

[0012] The sintering aid is a Y2O3-La2O3 composite rare earth oxide, and the sintering aid passes through a 3500-4000 mesh sieve; the active enhancement component includes alumina and silicon powder in a mass ratio of (6-8):(3-5); the composite binder includes aluminum dihydrogen phosphate solution and silane coupling agent KH-550 in a mass ratio of (3.5-4):1.

[0013] The preparation method of the composite ceramic powder in the above raw materials includes the following steps: micron-sized silicon powder: nano-sized titanium powder: zirconium dioxide powder: boric acid: urea: carbon black: calcium fluoride: polyethylene glycol in a mass ratio of (28-32): (23-27): (18-22): (5-7): (8-12): (10-14): (1-2): (0.4-0.6); zirconium dioxide powder and urea are mixed, and the mixture is heated to 650℃-700℃ and kept at that temperature for 2-3 hours under an ammonia atmosphere to obtain pre-nitrided ZrO2; the pre-nitrided ZrO2, nano-sized titanium powder, and micron-sized titanium dioxide powder are then mixed together. Silicon powder, boric acid, carbon black, calcium fluoride, and polyethylene glycol are mixed to obtain a mixture. Anhydrous ethanol is added, and the mixture is wet-milled to obtain a slurry. The slurry is dried into blocks, broken up, and passed through an 80-100 mesh sieve to obtain a precursor material. The precursor material is sintered under a nitrogen atmosphere, heated to 500-600℃ and held for 1-1.5 hours, then heated to 1200-1300℃ and held for 1.5-2 hours, then heated to 1550-1650℃ and held for 2-3 hours. The mixture is then cooled in the furnace, pulverized, and passed through a 2000-2500 mesh sieve to obtain composite ceramic powder.

[0014] In the above-mentioned method for preparing composite ceramic powder, the amount of anhydrous ethanol is 1.2 to 1.5 times the mass of the mixture; the wet ball milling time is 4 to 6 hours; the precursor material is loaded into a covered graphite crucible, compacted, and the lid has small holes for gas exchange; the median particle size of the micron-sized silicon powder is 5 μm to 10 μm; the median particle size of the nano-titanium powder is 50 nm to 100 nm; the median particle size of the zirconium dioxide powder is ≤1 μm; the median particle size of the boric acid is ≤2 μm; the median particle size of the urea is ≤5 μm; the median particle size of the carbon black is ≤0.3 μm; the median particle size of the calcium fluoride is 2 μm to 5 μm; and the number average molecular weight of the polyethylene glycol is 2000.

[0015] The preparation method of the MCR-reinforced aggregate in the above raw materials includes the following steps: mixing Mg(NO3)2·6H2O and Al(NO3)3·9H2O at a mass ratio of 1:(1.4-1.5) to obtain a mixed salt; preparing a 20wt%-25wt% mixed salt solution with water; adding 8%-12% citric acid by mass of the mixed salt; stirring to obtain a sol; mixing the sol with corundum particles at a mass ratio of 1:(4-6) until uniform; drying; heating to 500℃-550℃ in air atmosphere and holding for 1h-1.5h; then heating to 1250℃-1350℃ and holding for 1h. After 2-3 hours, a primary coating material is obtained. Lightly calcined magnesium oxide powder and polymethyl methacrylate are mixed at a mass ratio of (8-10):1 to obtain a mixture. 15%-20% of the mass of the mixture is added to a PVB ethanol solution, and the mixture is ball-milled to obtain a slurry. The slurry and the primary coating material are mixed evenly at a mass ratio of 1:(5-7), dried, and sintered under a flowing nitrogen atmosphere. The temperature is raised to 500℃-550℃ and held for 1-1.5 hours. The temperature is then raised to 1550℃-1650℃ and held for 2-3 hours. After cooling, MCR reinforced aggregate with a particle size range of 0.3mm-2.2mm is obtained.

[0016] In the above-mentioned method for preparing MCR-reinforced aggregate, the corundum particles are preheated to 200℃~250℃ and held for 20min~30min, then cooled before use; the stirring is carried out at 75℃~85℃ and 150r / min~250r / min for 20min~40min; the particle size range of the corundum particles is 0.5mm~2.0mm; the median particle size of the lightly calcined magnesium oxide powder is 0.8μm~2μm; the median particle size of the polymethyl methacrylate is 5μm~10μm; and the concentration of the PVB ethanol solution is 10wt%~15wt%.

[0017] The preparation method of the Y2O3-La2O3 composite rare earth oxide from the above raw materials includes the following steps: Y(NO3)3·6H2O and La(NO3)3·6H2O are mixed in a mass ratio of (1~1.5):1 to obtain a mixed salt. A 15wt%~20wt% mixed salt solution is prepared with water. Citric acid of 10%~15% of the mass of the mixed salt is added, stirred, and the pH is adjusted to 8.5~9.5. The mixture is stirred and allowed to stand to precipitate. The precipitate is washed with deionized water and anhydrous ethanol, dried, sintered in air atmosphere, heated to 500℃~550℃ and held for 1h~2h, heated to 850℃~950℃ and held for 3h~4h, cooled, dry ball milled, and passed through a 3500-4000 mesh sieve to obtain the Y2O3-La2O3 composite rare earth oxide.

[0018] The preparation method of the magnesium aluminum spinel precursor sol in the above raw materials includes the following steps: aluminum triacetylacetonate and acetylacetonate are mixed at a mass ratio of 1:(0.5-0.6), and dissolved in anhydrous ethanol at a material-to-liquid mass ratio of 1:(3-3.5). The mixture is refluxed at 70℃-75℃ for 2-2.5 hours, then cooled to 60℃-65℃ to obtain solution A; 38%-42% by mass of aluminum triacetylacetonate in Mg(NO3)2·6H2O is taken, and the mixture is added according to the material-to-liquid mass ratio. The solution was dissolved in ethylene glycol monomethyl ether at a liquid-to-mass ratio of 1:(3-3.5) to obtain solution B. Solution B was added dropwise to solution A under stirring at 60℃-65℃ and 300r / min-400r / min. After the addition was complete, 30%-35% of deionized water by mass of aluminum triacetylacetonate was added. The mixture was stirred at 60℃-65℃ for 24h-28h and then concentrated under reduced pressure to a solid content of 20wt%-25wt% to obtain magnesium aluminum spinel precursor sol.

[0019] In the above raw materials, the median particle size of the alumina is 0.8 μm to 2 μm.

[0020] In the above raw materials, the median particle size of the silicon powder is 2μm to 6μm.

[0021] Of the above raw materials, the density of the aluminum dihydrogen phosphate solution is 1.35 g / cm³. 3 ~1.40g / cm 3 .

[0022] The preparation method of the above-mentioned erosion-resistant ceramic composite magnesium-based refractory material includes the following steps:

[0023] S1: According to the mass fractions, the composite ceramic powder, MCR reinforced aggregate, sintering aid, active reinforcing component and fused magnesia with a particle size ≤0.074mm are dry-mixed evenly; the interface modifier is added and wet-mixed evenly; the remaining fused magnesia with the specified particle size is added and mixed evenly; finally, the composite binder is added and mixed evenly to obtain the billet.

[0024] S2: The billet is pressed into shape to obtain a blank;

[0025] S3: The green body is dried, sintered in a nitrogen atmosphere, heated to 550℃~600℃ and held for 1h~1.5h, heated to 1300℃~1350℃ and held for 2h~2.5h, heated to 1500℃~1550℃ and held for 3h~4h, and then cooled in the furnace to obtain the molded body.

[0026] In step S2 of the above preparation method, the blank is pressed into shape in one step under a pressure of 180MPa to 200MPa and held under pressure for 60 to 90 seconds to obtain a density of 3.00 g / cm³. 3 The above blanks.

[0027] In step S3 of the above preparation method, the green body is dried at room temperature for 20-26 hours, at 75-85°C for 3-4 hours, and at 110-130°C for 7-9 hours.

[0028] The present invention provides an erosion-resistant ceramic composite magnesium-based refractory material and its preparation method, which has the following beneficial effects:

[0029] I. This invention's refractory material, through component synergistic design and precise process control, solves the core problems of traditional magnesium-based refractories, such as high brittleness, mismatched thermal expansion, and difficulty in simultaneously achieving erosion resistance and thermal shock resistance. It achieves a balanced optimization of mechanical strength, high-temperature stability, corrosion resistance, and erosion resistance. By constructing a three-dimensional structural system of microscopic ceramic reinforcement network, macroscopic gradient skeleton support, and interface stress regulation, the material can withstand multiple harsh conditions, including temperatures above 1600℃, high-speed molten slag erosion, and temperature fluctuations, thus extending the service life of high-temperature industrial equipment linings.

[0030] Second, fused magnesia with precise particle size distribution is used as the matrix material. With the high temperature resistance and slag erosion resistance of high-purity MgO, the particles are tightly packed through three-stage particle size optimization, which improves the material density and lays the foundation for performance.

[0031] Third, the composite ceramic powder is pre-nitrided and sintered at multiple temperature ranges to form a composite ceramic phase with high hardness and low expansion coefficient, which fills the gaps in the matrix, builds a micro-reinforcing network, hinders crack propagation, and improves the resistance to erosion and corrosion.

[0032] IV. MCR reinforced aggregate has a gradient structure with corundum as the core, magnesium aluminum spinel as the transition layer, and magnesium oxide as the outer layer. This achieves a continuous transition of the coefficient of thermal expansion from the aggregate to the matrix, disperses thermal stress, forms a macroscopic skeleton, and improves the mechanical strength and toughness of the material.

[0033] MCR-reinforced aggregate is produced through corundum particle pretreatment, sol-gel coating, slurry coating, and multi-temperature sintering, with precise parameter matching in each step to optimize performance. The sol-gel coating stage forms a magnesium-aluminum spinel transition layer, whose coefficient of thermal expansion lies between that of corundum and the magnesium matrix, effectively alleviating interfacial stress. The slurry coating uses lightly calcined magnesium oxide powder and polymethyl methacrylate as raw materials, ball-milled with PVB ethanol solution to form a slurry. After coating, multi-temperature sintering removes organic components, forms appropriate porosity, and densifies the outer layer, creating a gradient structure of corundum core, spinel transition layer, and magnesium oxide outer layer. This structure enhances mechanical strength through the corundum core, achieves thermal expansion matching through the gradient layer, and strengthens compatibility with the matrix through the magnesium oxide outer layer, ultimately significantly improving the material's mechanical properties, thermal shock resistance, and slag erosion resistance.

[0034] Polymethyl methacrylate (PMMA) decomposes and volatilizes upon heating, forming pores that buffer stress and optimize structural compatibility. These small pores absorb the volume shrinkage differences between the slurry coating layer, the corundum core, and the transition layer during high-temperature sintering, preventing internal stress caused by uneven shrinkage, preventing cracking of the coating layer or delamination from the core, and ensuring the integrity of the gradient structure. The pores also reduce the rigid constraints between the aggregate and the magnesium matrix during thermal expansion, minimizing interfacial stress caused by differences in their coefficients of thermal expansion. Simultaneously, they provide microchannels for interfacial diffusion reactions at high temperatures, promoting the bonding between the aggregate and the matrix, and indirectly improving the material's thermal shock resistance and structural stability.

[0035] V. Interface Modifier (Magnesium Aluminum Spinel Precursor Sol): Prepared via sol-gel method, it possesses both fluidity and binding properties. During sintering, the sol transforms into magnesium aluminum spinel, filling the interfacial gaps between the composite ceramic powder, MCR aggregate, and magnesium matrix, thereby strengthening the interfacial strength. Simultaneously, its gradient thermal expansion characteristics alleviate interfacial stress, block slag penetration channels, reduce internal defects, and make the material more uniformly stressed, thus improving overall thermal stability, erosion resistance, and mechanical properties.

[0036] VI. The composite binder balances bonding strength and interfacial compatibility, promotes the bonding stability of each component during molding and sintering, and avoids interfacial delamination at high temperatures.

[0037] VII. In the material preparation method, the mixing step adopts the stepwise addition of interface modifier and binder to ensure that the interface modifier reacts fully with the powder first, and then is cured by the binder, so as to avoid the binder covering the particle surface and weakening the interface modification effect.

[0038] In summary, the microscopic ceramic phase of the composite ceramic powder fills the gaps between the matrix and aggregate, while the macroscopic gradient skeleton of the aggregate, enhanced by MCR, disperses stress. The combination of these two methods improves both the material's hardness and wear resistance, as well as its toughness and thermal shock resistance, resolving the problem of single-method reinforcement being ineffective. Interface modifiers optimize phase interface bonding at a chemical level, while composite binders enhance component adhesion at a physical level. Together, they eliminate interface defects, prevent interface separation at high temperatures, and ensure the material's integrity and stability. Sintering aids lower the activation energy of ceramic phase synthesis, and multi-stage heating provides suitable conditions for each reaction stage, promoting full reaction of all components and forming a composite system with a uniform structure and few defects. The formulation and process of this invention achieve synergy in component function complementarity, structural gradient matching, interface stress regulation, and process-promoted reaction, ultimately realizing comprehensive performance optimization. Detailed Implementation

[0039] The present invention will be further described below with reference to specific implementation examples, but the present invention is not limited to these embodiments.

[0040] Example 1

[0041] An erosion-resistant ceramic composite magnesium-based refractory material comprises the following raw materials in parts by weight: 60 parts fused magnesia, 6.5 parts composite ceramic powder, 6 parts MCR reinforcing aggregate, 2 parts sintering aid, 3 parts interface modifier, 11 parts active reinforcing component, and 6 parts composite binder.

[0042] The particle size distribution of the fused magnesia is as follows: 3mm < ≤ 5mm accounts for 22wt%, 1mm < ≤ 3mm accounts for 32wt%, 0.074mm < ≤ 1mm accounts for 33wt%, and ≤ 0.074mm accounts for 13wt%. The activity-enhancing components include alumina and silica powder in a mass ratio of 7:4; the alumina is α-Al2O3 with a median particle size of 1.2μm; and the silica powder has a median particle size of 4.1μm.

[0043] The preparation method of the composite ceramic powder includes the following steps: Preparing materials according to the mass ratio of micron-sized silicon powder: nano-sized titanium powder: zirconium dioxide powder: boric acid: urea: carbon black: calcium fluoride: polyethylene glycol = 30:25:20:6:10:12:1.5:0.5; mixing zirconium dioxide powder (median particle size 0.8 μm) with urea (median particle size 3.5 μm), and heating to 680℃ at 3℃ / min for 2.5 h under a flowing ammonia atmosphere (150 mL / min) and holding (to form a layer of zirconium oxynitride ZrO). x N y The active layer was cooled to room temperature to obtain pre-nitrided ZrO2. Pre-nitrided ZrO2, nano-titanium powder (median particle size 85 nm), micron-sized silicon powder (median particle size 7.6 μm), boric acid (median particle size 1.7 μm), carbon black (median particle size 0.2 μm), calcium fluoride (median particle size 4.3 μm), and polyethylene glycol (number average molecular weight 2000) were mixed to obtain a mixture. Anhydrous ethanol was added at a material-to-liquid mass ratio of 1:1.3, and the mixture was wet-milled for 5 hours (ball-to-material mass ratio 5:1, rotation speed 12 r / min). The grinding balls (diameter range 3mm to 6mm) are used to obtain a slurry; the slurry is dried into blocks, broken up, and passed through an 80-mesh sieve to obtain the precursor material; the precursor material is loaded into a covered graphite crucible, compacted, and the lid has small holes for gas exchange; sintering is carried out under a nitrogen atmosphere: the temperature is increased to 550℃ at 3℃ / min and held for 1.5h, then increased to 1250℃ at 5℃ / min and held for 1.5h, then increased to 1600℃ at 3℃ / min and held for 2.5h, cooled in the furnace, pulverized, and passed through a 2000-mesh sieve to obtain composite ceramic powder.

[0044] The preparation method of MCR reinforced aggregate includes the following steps: Corundum particles (particle size range 0.5mm~2.0mm) are heated to 230℃ and held for 25min (to remove surface moisture and impurities), then cooled for later use; Mg(NO3)2·6H2O and Al(NO3)3·9H2O are mixed at a mass ratio of 1:1.46 to obtain a mixed salt; a 22wt% mixed salt solution is prepared with water; 10% of the mixed salt mass of citric acid is added; the mixture is stirred at 80℃ and 200r / min for 30min to prepare a sol; the sol and corundum particles are mixed evenly at a mass ratio of 1:5; dried at 120℃ for 12h; heated to 530℃ at 3℃ / min and held for 1h in air atmosphere; then heated to 1300℃ at 5℃ / min and held for 2.5h to obtain… Primary coating material: Lightly calcined magnesium oxide powder (median particle size 1.4 μm) and polymethyl methacrylate (median particle size 7.5 μm) were mixed at a mass ratio of 9:1 to obtain a mixture. 18% of the mixture mass of PVB ethanol solution (concentration 12 wt%) was added, and the mixture was ball-milled for 3.5 h (ball mass ratio 3:1, rotation speed 12 r / min, ball diameter range 3 mm to 6 mm) to prepare a slurry. The slurry and primary coating material were mixed evenly at a mass ratio of 1:6, dried at room temperature for 10 h, and sintered under a flowing nitrogen atmosphere. The temperature was increased to 530℃ at 3℃ / min and held for 1 h (to remove PMMA), and then increased to 1600℃ at 5℃ / min and held for 2.5 h. After cooling and dispersing, MCR reinforced aggregate with a particle size range of 0.3 mm to 2.2 mm was obtained.

[0045] The sintering aid is a Y2O3-La2O3 composite rare earth oxide. The preparation method of the Y2O3-La2O3 composite rare earth oxide includes the following steps: Y(NO3)3·6H2O and La(NO3)3·6H2O are mixed at a mass ratio of 1.2:1 to obtain a mixed salt; an 18wt% mixed salt solution is prepared with water; 12% citric acid (by mass of the mixed salt) is added; the mixture is stirred at 200 r / min for 30 min; 25wt% ammonia is added dropwise to adjust the pH to 9.0; and the mixture is then heated at 40℃ for 20 minutes. Stir at 0 r / min for 50 min, let stand for 24 h to precipitate; take the precipitate and wash with deionized water until pH 7.0, wash three times with anhydrous ethanol, dry at 120℃ for 6 h, sinter in air atmosphere, heat to 530℃ at 5℃ / min and hold for 1.5 h, continue to heat to 900℃ and hold for 3.5 h, cool, dry ball mill for 1 h (ball mass ratio 3:1, rotation speed 12 r / min, ball diameter range 3 mm to 6 mm), pass through a 3500 mesh sieve to obtain Y2O3-La2O3 composite rare earth oxide.

[0046] The interface modifier is a magnesium aluminum spinel precursor sol, which is prepared by the following steps: aluminum triacetylacetonate and acetylacetonate are mixed at a mass ratio of 1:0.55 and dissolved in anhydrous ethanol at a mass ratio of 1:3.2. The mixture is refluxed at 73℃ and 250 r / min for 2 h, and then cooled to 62℃ to obtain solution A. 40% of the mass of aluminum triacetylacetonate in Mg(NO3)2·6H2O is dissolved in ethylene glycol monomethyl ether at a mass ratio of 1:3.2 to obtain solution B. Solution B is added dropwise to solution A at a rate of 2.5 mL / min under stirring at 62℃ and 350 r / min. After the addition is complete, 32% of the mass of aluminum triacetylacetonate in deionized water is added. The mixture is stirred continuously at 62℃ for 26 h (hydrolysis-condensation reaction), and then concentrated under reduced pressure at 55℃ to a solid content of 23 wt% to obtain the magnesium aluminum spinel precursor sol.

[0047] The preparation method of the composite binder includes the following steps: Weigh aluminum hydroxide and 85wt% phosphoric acid at a mass ratio of 1:4.4; dilute the 85wt% phosphoric acid to a volume concentration of 55%; add aluminum hydroxide; stir and react at 85℃ for 5 hours until completely transparent; after cooling, adjust the density to 1.38 g / cm³. 3 Aluminum dihydrogen phosphate solution was obtained, and 0.15% (by mass) of 8-hydroxyquinoline was added as a stabilizer. Before use, the aluminum dihydrogen phosphate solution and KH-550 were stirred and mixed evenly at room temperature at a mass ratio of 3.8:1 to obtain a composite binder.

[0048] The preparation method of the above-mentioned erosion-resistant ceramic composite magnesium-based refractory material includes the following steps:

[0049] S1 Mixing: According to the mass proportions, the composite ceramic powder, MCR reinforced aggregate, sintering aid, active reinforcing component, and fused magnesia with a particle size ≤0.074mm are dry-mixed in a mixer at 25r / min for 12min; the interface modifier is added, and the mixture is wet-mixed at 25r / min for 18min; the remaining fused magnesia with the specified particle size is added, and the mixture is mixed at 25r / min for 12min; finally, the composite binder is added, and the mixture is mixed at 28r / min for 25min to obtain the billet;

[0050] S2 molding: The billet is pressed into shape in one step under a pressure of 190 MPa and held under pressure for 75 seconds to obtain a density of 3.00 g / cm³. 3 The above blanks;

[0051] S3 sintering: The green body is dried at room temperature for 23 hours, at 80°C for 3.5 hours, at 120°C for 8 hours, and sintered in a nitrogen atmosphere. The temperature is increased to 580°C at 3°C / min and held for 1 hour, increased to 1320°C at 5°C / min and held for 2 hours, increased to 1530°C at 3°C / min and held for 3.5 hours, and then cooled in the furnace to obtain the shaped body.

[0052] Example 2

[0053] An erosion-resistant ceramic composite magnesium-based refractory material comprises the following raw materials in parts by weight: 58 parts fused magnesia, 8 parts composite ceramic powder, 5 parts MCR reinforcing aggregate, 2.5 parts sintering aid, 2.5 parts interface modifier, 14 parts active reinforcing component, and 5 parts composite binder.

[0054] The particle size distribution of the fused magnesia is as follows: 3mm < ≤ 5mm accounts for 20wt%, 1mm < ≤ 3mm accounts for 30wt%, 0.074mm < ≤ 1mm accounts for 35wt%, and ≤ 0.074mm accounts for 15wt%. The activity-enhancing components include alumina and silica powder in a mass ratio of 6:5; the alumina is α-Al2O3 with a median particle size of 0.8μm; and the silica powder has a median particle size of 6μm.

[0055] The preparation method of the composite ceramic powder includes the following steps: Preparing materials according to the mass ratio of micron-sized silicon powder: nano-sized titanium powder: zirconium dioxide powder: boric acid: urea: carbon black: calcium fluoride: polyethylene glycol = 28:27:18:7:8:14:1:0.6; mixing zirconium dioxide powder (median particle size 0.6 μm) with urea (median particle size 5 μm), and heating to 650℃ at 4℃ / min for 3 hours under a flowing ammonia atmosphere (100 mL / min) (to form a layer of zirconium oxynitride ZrO). x N y The active layer was cooled to room temperature to obtain pre-nitrided ZrO2. Pre-nitrided ZrO2, nano-titanium powder (median particle size 50 nm), micron-sized silicon powder (median particle size 10 μm), boric acid (median particle size 1 μm), carbon black (median particle size 0.3 μm), calcium fluoride (median particle size 2 μm), and polyethylene glycol (number average molecular weight 2000) were mixed to obtain a mixture. Anhydrous ethanol was added at a material-to-liquid mass ratio of 1:1.5, and the mixture was wet-milled for 4 hours (ball-to-material mass ratio 5:1, rotation speed 15 r / min). The slurry was obtained by sizing balls with a diameter of 3mm to 6mm; dried into blocks, broken up, and passed through an 80-mesh sieve to obtain the precursor material; the precursor material was loaded into a covered graphite crucible, compacted, and the lid was left with a small hole for gas exchange; sintering was carried out under a nitrogen atmosphere: the temperature was increased to 500℃ at 4℃ / min and held for 1.5h, then increased to 1300℃ at 5℃ / min and held for 1.5h, then increased to 1550℃ at 3℃ / min and held for 3h, cooled in the furnace, pulverized, and passed through a 2000-mesh sieve to obtain composite ceramic powder.

[0056] The preparation method of MCR reinforced aggregate includes the following steps: Corundum particles (particle size range 0.5mm~2.0mm) are heated to 200℃ and held for 30min (to remove surface moisture and impurities), then cooled for later use; Mg(NO3)2·6H2O and Al(NO3)3·9H2O are mixed at a mass ratio of 1:1.4 to obtain a mixed salt; a 25wt% mixed salt solution is prepared with water; 8% citric acid (by mass of the mixed salt) is added; the mixture is stirred at 85℃ and 150r / min for 40min to prepare a sol; the sol and corundum particles are mixed evenly at a mass ratio of 1:4; the mixture is dried at 130℃ for 10h; the temperature is increased to 500℃ at 4℃ / min and held for 1.5h in air atmosphere; and then increased to 1350℃ at 5℃ / min and held for 2h. A primary coating material was obtained; lightly calcined magnesium oxide powder (median particle size 2 μm) and polymethyl methacrylate (median particle size 5 μm) were mixed at a mass ratio of 10:1 to obtain a mixture. 15% of the mixture mass of PVB ethanol solution (concentration 15 wt%) was added, and the mixture was ball-milled for 3 hours (ball mass ratio 3:1, rotation speed 15 r / min, ball diameter range 3 mm to 6 mm) to prepare a slurry. The slurry and the primary coating material were mixed evenly at a mass ratio of 1:5, dried at room temperature for 12 hours, and sintered under a flowing nitrogen atmosphere. The temperature was increased to 550℃ at 3℃ / min and held for 1 hour (to remove PMMA), and then increased to 1550℃ at 6℃ / min and held for 3 hours. After cooling and dispersing, MCR reinforced aggregate with a particle size range of 0.3 mm to 2.2 mm was obtained.

[0057] The sintering aid is a Y2O3-La2O3 composite rare earth oxide. The preparation method of the Y2O3-La2O3 composite rare earth oxide includes the following steps: Y(NO3)3·6H2O and La(NO3)3·6H2O are mixed at a mass ratio of 1:1 to obtain a mixed salt; a 20wt% mixed salt solution is prepared with water; 10% citric acid (by mass of the mixed salt) is added; the mixture is stirred at 250 r / min for 20 min; 26wt% ammonia is added dropwise to adjust the pH to 8.5; and the mixture is then sintered at 45℃. Stir at 50 r / min for 60 min, let stand for 22 h to precipitate; take the precipitate and wash with deionized water until pH 7.2, wash twice with anhydrous ethanol, dry at 130℃ for 5 h, sinter in air atmosphere, heat to 500℃ at 6℃ / min and hold for 2 h, continue to heat to 850℃ and hold for 4 h, cool, dry ball mill for 1 h (ball mass ratio 3:1, rotation speed 15 r / min, ball diameter range 3 mm to 6 mm), pass through a 3500 mesh sieve to obtain Y2O3-La2O3 composite rare earth oxide.

[0058] The interface modifier is a magnesium aluminum spinel precursor sol, which is prepared by the following steps: aluminum triacetylacetonate and acetylacetonate are mixed at a mass ratio of 1:0.5 and dissolved in anhydrous ethanol at a mass ratio of 1:3.5. The mixture is refluxed at 70℃ and 300 r / min for 2 h, and then cooled to 65℃ to obtain solution A. 38% of the mass of aluminum triacetylacetonate in Mg(NO3)2·6H2O is dissolved in ethylene glycol monomethyl ether at a mass ratio of 1:3.5 to obtain solution B. Under stirring at 65℃ and 300 r / min, solution B is added dropwise to solution A at a rate of 3 mL / min. After the addition is complete, 30% of the mass of aluminum triacetylacetonate in deionized water is added. The mixture is stirred continuously at 65℃ for 28 h (hydrolysis-condensation reaction), and then concentrated under reduced pressure at 50℃ to a solid content of 25 wt% to obtain the magnesium aluminum spinel precursor sol.

[0059] The preparation method of the composite binder includes the following steps: Weigh aluminum hydroxide and 85wt% phosphoric acid at a mass ratio of 1:4.2; dilute the 85wt% phosphoric acid to a volume concentration of 60%; add aluminum hydroxide; stir and react at 80℃ for 6 hours until completely transparent; after cooling, adjust the density to 1.35 g / cm³. 3 Aluminum dihydrogen phosphate solution was obtained, and 0.2% (by mass) of 8-hydroxyquinoline was added as a stabilizer. Before use, the aluminum dihydrogen phosphate solution and KH-550 were stirred and mixed evenly at room temperature at a mass ratio of 3.5:1 to obtain a composite binder.

[0060] The preparation method of the above-mentioned erosion-resistant ceramic composite magnesium-based refractory material includes the following steps:

[0061] S1 Mixing: According to the mass proportions, the composite ceramic powder, MCR reinforced aggregate, sintering aid, active reinforcing component, and fused magnesia with a particle size ≤0.074mm are dry-mixed in a mixer at 20r / min for 15min; the interface modifier is added and wet-mixed at 20r / min for 20min; the remaining fused magnesia with the specified particle size is added and mixed at 20r / min for 15min; finally, the composite binder is added and mixed at 25r / min for 30min to obtain the billet;

[0062] S2 molding: The billet is pressed into shape in one step under a pressure of 180MPa and held under pressure for 90 seconds to obtain a density of 3.00g / cm³. 3 The above blanks;

[0063] S3 sintering: The green body is dried at room temperature for 20 hours, dried at 85℃ for 3 hours, dried at 130℃ for 7 hours, sintered in a nitrogen atmosphere, heated to 550℃ at 4℃ / min and held for 1.5 hours, heated to 1350℃ at 5℃ / min and held for 2 hours, heated to 1500℃ at 4℃ / min and held for 4 hours, and then cooled in the furnace to obtain the shaped body.

[0064] Example 3

[0065] An erosion-resistant ceramic composite magnesium-based refractory material comprises the following raw materials in parts by weight: 62 parts fused magnesia, 5 parts composite ceramic powder, 7 parts MCR reinforcing aggregate, 1.5 parts sintering aid, 3.5 parts interface modifier, 9 parts active reinforcing component, and 7 parts composite binder.

[0066] The particle size distribution of the fused magnesia is as follows: 25 wt% for particles 3 mm < ≤ 5 mm, 35 wt% for particles 1 mm < ≤ 3 mm, 30 wt% for particles 0.074 mm < ≤ 1 mm, and 10 wt% for particles ≤ 0.074 mm. The activity-enhancing components include alumina and silica powder in a mass ratio of 8:3; the alumina is α-Al₂O₃ with a median particle size of 2 μm; the silica powder has a median particle size of 2 μm.

[0067] The preparation method of the composite ceramic powder includes the following steps: Preparing materials according to the mass ratio of micron-sized silicon powder: nano-sized titanium powder: zirconium dioxide powder: boric acid: urea: carbon black: calcium fluoride: polyethylene glycol = 32:23:22:5:12:10:2:0.4; mixing zirconium dioxide powder (median particle size 1 μm) with urea (median particle size 2 μm), and heating to 700℃ at 3℃ / min for 2 hours under a flowing ammonia atmosphere (200 mL / min) and holding for 2 hours (to form a layer of zirconium oxynitride ZrO). x N y The active layer was cooled to room temperature to obtain pre-nitrided ZrO2. Pre-nitrided ZrO2, nano-titanium powder (median particle size 100 nm), micron-sized silicon powder (median particle size 5 μm), boric acid (median particle size 2 μm), carbon black (median particle size 0.1 μm), calcium fluoride (median particle size 5 μm), and polyethylene glycol (number average molecular weight 2000) were mixed to obtain a mixture. Anhydrous ethanol was added at a material-to-liquid mass ratio of 1:1.2, and the mixture was wet-milled for 6 hours (ball-to-material mass ratio 5:1, speed 10 r / min). The grinding balls (diameter range 3mm to 6mm) are used to obtain a slurry; the slurry is dried into blocks, broken up, and passed through a 100-mesh sieve to obtain the precursor material; the precursor material is loaded into a covered graphite crucible, compacted, and the lid has a small hole for gas exchange; sintering is carried out under a nitrogen atmosphere: the temperature is increased to 600℃ at 3℃ / min and held for 1h, then increased to 1200℃ at 6℃ / min and held for 2h, then increased to 1650℃ at 2℃ / min and held for 2h, cooled in the furnace, pulverized, and passed through a 2500-mesh sieve to obtain composite ceramic powder.

[0068] The preparation method of MCR reinforced aggregate includes the following steps: Corundum particles (particle size range 0.5mm~2.0mm) are heated to 250℃ and held for 20min (to remove surface moisture and impurities), then cooled for later use; Mg(NO3)2·6H2O and Al(NO3)3·9H2O are mixed at a mass ratio of 1:1.5 to obtain a mixed salt; a 20wt% mixed salt solution is prepared with water; 12% citric acid (by mass of the mixed salt) is added; the mixture is stirred at 75℃ and 250r / min for 20min to prepare a sol; the sol and corundum particles are mixed evenly at a mass ratio of 1:6; the mixture is dried at 110℃ for 14h; the temperature is increased to 550℃ at 3℃ / min and held for 1h in air atmosphere; then the temperature is increased to 1250℃ at 6℃ / min and held for 3h to obtain… Primary coating material: Lightly calcined magnesium oxide powder (median particle size 0.8 μm) and polymethyl methacrylate (median particle size 10 μm) were mixed at a mass ratio of 8:1 to obtain a mixture. 20% of the mixture mass of PVB ethanol solution (concentration 10 wt%) was added, and the mixture was ball-milled for 4 hours (ball mass ratio 3:1, rotation speed 10 r / min, ball diameter range 3 mm to 6 mm) to prepare a slurry. The slurry and primary coating material were mixed evenly at a mass ratio of 1:7, dried at room temperature for 8 hours, and sintered under a flowing nitrogen atmosphere. The temperature was increased to 500℃ at 4℃ / min and held for 1.5 hours (to remove PMMA), and then increased to 1650℃ at 5℃ / min and held for 2 hours. After cooling and dispersing, MCR reinforced aggregate with a particle size range of 0.3 mm to 2.2 mm was obtained.

[0069] The sintering aid is a Y2O3-La2O3 composite rare earth oxide. The preparation method of the Y2O3-La2O3 composite rare earth oxide includes the following steps: Y(NO3)3·6H2O and La(NO3)3·6H2O are mixed at a mass ratio of 1.5:1 to obtain a mixed salt; a 15wt% mixed salt solution is prepared with water; 15% citric acid (by mass of the mixed salt) is added; the mixture is stirred at 150 r / min for 40 min; 24wt% ammonia is added dropwise to adjust the pH to 9.5; and the mixture is then heated at 35℃. Stir at 50 r / min for 40 min, let stand for 26 h to precipitate; take the precipitate and wash with deionized water until pH 6.8, wash with anhydrous ethanol 4 times, dry at 110℃ for 7 h, sinter in air atmosphere, heat up to 550℃ at 5℃ / min and hold for 1 h, continue to heat up to 950℃ and hold for 3 h, cool, dry ball mill for 1.5 h (ball mass ratio 3:1, rotation speed 10 r / min, ball diameter range 3 mm to 6 mm), pass through a 4000 mesh sieve to obtain Y2O3-La2O3 composite rare earth oxide.

[0070] The interface modifier is a magnesium aluminum spinel precursor sol, which is prepared by the following steps: aluminum triacetylacetonate and acetylacetonate are mixed at a mass ratio of 1:0.6 and dissolved in anhydrous ethanol at a mass ratio of 1:3. The mixture is refluxed at 75°C and 200 r / min for 2.5 h, and then cooled to 60°C to obtain solution A. 42% of the mass of aluminum triacetylacetonate in Mg(NO3)2·6H2O is dissolved in ethylene glycol monomethyl ether at a mass ratio of 1:3 to obtain solution B. Solution B is added dropwise to solution A at a rate of 2 mL / min under stirring at 60°C and 400 r / min. After the addition is complete, 35% of the mass of aluminum triacetylacetonate in deionized water is added. The mixture is stirred continuously at 60°C for 24 h (hydrolysis-condensation reaction). The mixture is then concentrated under reduced pressure at 60°C to a solid content of 20 wt% to obtain the magnesium aluminum spinel precursor sol.

[0071] The preparation method of the composite binder includes the following steps: Weigh aluminum hydroxide and 85wt% phosphoric acid at a mass ratio of 1:4.6; dilute the 85wt% phosphoric acid to a 50% volume concentration; add aluminum hydroxide; stir and react at 90℃ for 4 hours until completely transparent; after cooling, adjust the density to 1.40 g / cm³. 3 Aluminum dihydrogen phosphate solution was obtained, and 0.1% (by mass) of 8-hydroxyquinoline was added as a stabilizer. Before use, the aluminum dihydrogen phosphate solution and KH-550 were stirred and mixed evenly at room temperature at a mass ratio of 4:1 to obtain a composite binder.

[0072] The preparation method of the above-mentioned erosion-resistant ceramic composite magnesium-based refractory material includes the following steps:

[0073] S1 Mixing: According to the mass proportions, the composite ceramic powder, MCR reinforced aggregate, sintering aid, active reinforcing component, and fused magnesia with a particle size ≤0.074mm are dry-mixed in a mixer at 30r / min for 10min; the interface modifier is added and wet-mixed at 30r / min for 15min; the remaining fused magnesia with the specified particle size is added and mixed at 30r / min for 10min; finally, the composite binder is added and mixed at 30r / min for 20min to obtain the billet;

[0074] S2 molding: The billet is pressed into shape in one step under a pressure of 200MPa and held under pressure for 60 seconds to obtain a density of 3.00g / cm³. 3 The above blanks;

[0075] S3 sintering: The green body is dried at room temperature for 26 hours, at 75°C for 4 hours, at 110°C for 9 hours, and sintered in a nitrogen atmosphere. The temperature is increased to 600°C at 3°C / min and held for 1 hour, increased to 1300°C at 6°C / min and held for 2.5 hours, increased to 1550°C at 3°C / min and held for 3 hours, and then cooled in the furnace to obtain the shaped body.

[0076] The raw material specifications or sources involved in the above embodiments are as follows: MgO content of fused magnesia ≥ 99.5%. Purity of micron-sized silica powder ≥ 99.0%. Purity of nano-titanium powder ≥ 99.0%. Purity of zirconium dioxide powder (ZrO2) ≥ 99.5%, monoclinic phase. Purity of boric acid (H3BO3) ≥ 99.0%. Purity of urea (CO(NH2)2) ≥ 99.0%. Purity of carbon black ≥ 99.0%. Purity of calcium fluoride (CaF2) ≥ 99.0%. Number average molecular weight of polyethylene glycol is 2000, sourced from Jinan Jinrihe Chemical Co., Ltd. Al2O3 content of corundum particles ≥ 99.0%. Purity of Mg(NO3)2·6H2O ≥ 98.0%. Purity of Al(NO3)3·9H2O ≥ 99.0%. Purity of citric acid ≥ 99.0%. Lightly calcined magnesium oxide powder is magnesite (MgCO3 > 90wt%) calcined at 900℃ for 2 hours. Polymethyl methacrylate (PMMA) has a purity of 98% and is sourced from Hubei Hengjingrui Chemical Co., Ltd. PVB is polyvinyl butyral, sourced from Hubei Wande Chemical Co., Ltd. Y(NO3)3·6H2O has a purity ≥ 99.0%. La(NO3)3·6H2O has a purity ≥ 98.0%. Aluminum triacetylacetonate has a purity ≥ 99%. Acetylacetone has a purity ≥ 99.5%. Ethylene glycol monomethyl ether has a purity ≥ 99.5% and is sourced from Jinan Jinhao Chemical Co., Ltd. Aluminum oxide is α-Al2O3 with a purity ≥ 99%. Silica powder has a purity ≥ 99.0%. Aluminum hydroxide has a purity ≥ 99%. Phosphoric acid has a concentration of 85wt% and is sourced from Jinan Shanhai Chemical Technology Co., Ltd. 8-Hydroxyquinoline has a purity ≥ 99%. KH-550 is γ-aminopropyltriethoxysilane with a purity of 98%, sourced from Hubei Zhenbo Chemical Co., Ltd.

[0077] Comparative Example 1

[0078] The difference from Example 1 is that the composite ceramic powder is replaced with MCR reinforced aggregate.

[0079] Comparative Example 2

[0080] The difference from Example 1 is that composite ceramic powder is used instead of MCR reinforced aggregate.

[0081] Comparative Example 3

[0082] The difference from Example 1 is that the composite ceramic powder is directly replaced by a mixture of micron-sized silicon powder, nano-sized titanium powder, zirconium dioxide powder, boric acid, urea, carbon black, calcium fluoride and polyethylene glycol.

[0083] Comparative Example 4

[0084] The difference from Example 1 is that in the preparation of the composite ceramic powder, micron-sized silicon powder, nano-sized titanium powder, zirconium dioxide powder, boric acid, urea, carbon black, calcium fluoride, and polyethylene glycol are directly mixed, wet-ball-milled in anhydrous ethanol, and sintered at 550°C and 1250°C. That is, the steps of preparing pre-nitrided ZrO2 and sintering at 1600°C are omitted.

[0085] Comparative Example 5

[0086] The difference from Example 1 is that corundum particles are directly used as the MCR-reinforced aggregate.

[0087] Comparative Example 6

[0088] The difference from Example 1 is that in the preparation of MCR reinforced aggregate, sol-gel coating and sintering are not used, but slurry coating and sintering are performed directly.

[0089] Comparative Example 7

[0090] The difference from Example 1 is that the slurry coating sintering is not used in the preparation of MCR reinforced aggregate, that is, the MCR reinforced aggregate is a one-time coating material.

[0091] Comparative Example 8

[0092] The difference from Example 1 is that in the preparation of MCR reinforced aggregate, the 1300℃ sintering step is omitted after sol coating and the 1600℃ sintering step is omitted after slurry coating; that is, both are sintered at a low temperature of 530℃.

[0093] Comparative Example 9

[0094] The difference from Example 1 is that no interface modifier is added.

[0095] Comparative Example 10

[0096] The difference from Example 1 is that the interface modifier is replaced by solution A (concentrated to a total content of 23wt% of aluminum triacetylacetonate and acetylacetonate after reflux reaction).

[0097] Comparative Example 11

[0098] The difference from Example 1 is that in the preparation method S1 of the refractory material, the interface modifier and the composite binder are added at the end and mixed at 28 r / min for 25 min to obtain the billet.

[0099] I. Bulk density and apparent porosity:

[0100] Sample specifications: 50mm×50mm×50mm cube, 3 parallel samples.

[0101] The testing steps include: drying the specimen in a 110℃ oven for 24 hours until constant weight, cooling to room temperature, and weighing the dried mass m1. The sample is then saturated with water by boiling, immersing it in boiling water and maintaining boiling for 2 hours. After cooling to room temperature (25℃), the saturated mass m2 is weighed. Finally, the saturated specimen is suspended in water, completely submerged without contacting the container wall, and the mass in the water m3 is weighed. The bulk density ρ (g / cm³) is also measured. 3 )=m1 / (m2-m3); Apparent porosity P (%)=[(m2-m1) / (m2-m3)]×100%.

[0102] II. Compressive strength at room temperature:

[0103] Sample specifications: 50mm×50mm×50mm cube, 3 parallel samples.

[0104] The testing procedure includes: drying the specimen in a 110℃ oven for 12 hours and then cooling it to room temperature. On a universal testing machine, a uniform load of 1 MPa / s is applied until the specimen fails, and the maximum failure load F is recorded. The compressive strength σ = F / S, where S is the area of ​​the specimen subjected to pressure.

[0105] III. Flexural strength at room temperature:

[0106] Sample specifications: 100mm×10mm×10mm cuboid, 3 parallel samples.

[0107] The testing steps include: drying the specimen in a 110℃ oven for 12 hours and then cooling it to room temperature. A three-point bending method is used, with a support span of 80 mm, and a uniform load of 0.5 MPa / s is applied until fracture. The maximum load F at fracture is recorded. The flexural strength σ = (3FL) / (2bh) 2 ), where F is the fracture load, L is the span, and b and h are the width and height of the specimen.

[0108] IV. Flexural strength at 1500℃:

[0109] Sample specifications: 100mm×10mm×10mm cuboid, 3 parallel samples.

[0110] The testing steps included: heating to 1500℃ at a rate of 5℃ / min under a nitrogen atmosphere and holding for 2 hours. A three-point bending method was used, with a support span of 80mm, and a uniform load of 0.5MPa / s was applied until fracture, recording the maximum load F at fracture. Flexural strength σ = (3FL) / (2bh) 2 ), where F is the fracture load, L is the span, and b and h are the width and height of the specimen.

[0111] V. Thermal shock resistance at 1500℃:

[0112] Sample specifications: 100mm×50mm×25mm rectangular strip, 3 parallel samples.

[0113] The testing procedure includes: placing the sample in a box furnace preheated to 1500℃ and holding it at that temperature for 30 minutes; quickly removing it and immediately immersing it vertically in flowing water at 25℃ for rapid cooling for 3 minutes; after removal, drying it at 110℃ for 1 hour; after cooling, observing the surface condition using a 10x magnifying glass; and repeating this cycle. The number of thermal shock cycles required for the appearance of the first visible crack on the sample is recorded.

[0114] VI. Permanent linear change rate at 1500℃:

[0115] Sample specifications: 100mm×5mm×5mm cuboid, 3 parallel samples.

[0116] The testing steps include: measuring the initial length L1 at room temperature along the length of the sample. Heating the sample to 1500℃ at a rate of 5℃ / min, holding for 3 hours, and then cooling it to room temperature in the furnace. Measuring the sample length L2 again. The permanent linear change rate (%) = [(L2-L1) / L1] × 100%.

[0117] VII. Static slag erosion resistance at 1600℃:

[0118] Sample specifications: Cylindrical crucible sample with an outer diameter of 50 mm, an inner diameter of 20 mm, and a height of 50 mm, with an open top, and 3 parallel samples.

[0119] The testing procedure includes: filling a crucible with 20g of metallurgical slag (CaO:SiO2:Al2O3 = 45:40:15 by mass), placing it in a high-temperature furnace, heating it to 1600℃ at a rate of 5℃ / min, and holding it at that temperature for 6 hours. After cooling in the furnace, the crucible is cut open along its central axis, and the erosion interface is observed using a stereomicroscope under 50x magnification to measure the maximum erosion depth (mm).

[0120] 8. High-temperature erosion resistance at 1600℃:

[0121] Sample specifications: 100mm×100mm×50mm cuboid, with one 100mm×100mm face designated as the scour surface, and 3 parallel samples.

[0122] The testing steps include: weighing the initial mass m1 of the specimen; fixing the specimen in a high-temperature erosion testing machine, with the eroded surface at a 30° angle to the horizontal direction, and the slag flow direction perpendicular to the center of the surface, with the nozzle 50 mm from the specimen surface; heating the specimen to 1600°C at 8.0°C / min and holding for 1 hour under a nitrogen atmosphere; vertically spraying molten slag (CaO:SiO2:Al2O3 = 45:40:15 mass ratio) at 1600°C onto the specimen surface at a constant flow rate of 5.0 kg / h, and continuing erosion for 2 hours; stopping heating after erosion and cooling to room temperature under nitrogen protection; removing the solidified slag layer adhering to the specimen surface and weighing the specimen after erosion, m2; and calculating the mass loss rate η = (m1 - m2) / m1 × 100%.

[0123] Table 1. Test Results (Average)

[0124]

[0125] The results above show that the material properties are jointly determined by the function of key components, the interface bonding state, and the degree of sintering densification. The example achieves a performance breakthrough through collaborative design, while the comparative example suffers performance degradation due to defects in a single link.

[0126] The synergistic effect of composite ceramic powder and MCR reinforced aggregate is lacking: Composite ceramic powder, after pre-nitriding and multi-temperature sintering, forms a ZrOxNy-TiC-Si3N4 composite ceramic phase. With its high hardness and low coefficient of thermal expansion, it constructs a microscopic strengthening network, hindering crack propagation and improving resistance to erosion and scour. MCR reinforced aggregate, through its corundum core, magnesium-aluminum spinel transition layer, and magnesium oxide outer layer gradient structure, achieves thermal expansion matching, disperses thermal stress, and forms a macroscopic framework, improving mechanical strength and toughness. If MCR reinforced aggregate is used to replace composite ceramic powder, the lack of a microscopic ceramic phase to fill the matrix gaps leads to increased interface defects and a significant deterioration in thermal shock resistance and scour resistance. If composite ceramic powder is used to replace MCR reinforced aggregate, the lack of macroscopic framework support results in a significant decrease in material density and mechanical strength, ineffective dispersion of thermal stress, and very poor thermal shock resistance.

[0127] Defects in the preparation process of composite ceramic powder: The pre-nitriding step of composite ceramic powder generates a ZrOxNy active layer, which reduces interfacial energy and promotes uniform growth of ceramic phases; high-temperature sintering at 1600℃ is a necessary condition for the formation of stable, high-hardness ceramic phases such as TiC and Si3N4. If the raw materials are directly mixed without sintering, it is only a physical mixture, which cannot form a continuous ceramic strengthening network, and the difference in thermal expansion of each component leads to thermal stress concentration; if the pre-nitriding and high-temperature sintering steps are omitted, the ceramic phase synthesis rate is low, the grains are coarse, the internal defects of the material increase dramatically, the degree of densification is insufficient, and the resistance to erosion, corrosion and mechanical properties are comprehensively deteriorated.

[0128] Defects in the preparation process of MCR-reinforced aggregates: Sol-coating, slurry-coating, and high-temperature sintering are crucial for forming a gradient structure in MCR-reinforced aggregates. Sol-coating generates a magnesium-aluminum spinel transition layer, mitigating the thermal expansion difference between corundum and the magnesium matrix; slurry-coating generates a magnesium oxide outer layer, achieving continuity with the matrix composition; high-temperature sintering ensures the densification of the coating layer. If pure corundum particles are used instead, the lack of a gradient layer leads to interfacial stress concentration, easily generating microcracks that become channels for slag erosion and penetration; if sol-coating is omitted, the magnesium oxide layer is in direct contact with the corundum, significantly increasing interfacial stress and resulting in weak bonding; if slurry-coating is omitted, the large difference in composition between the aggregate and the matrix leads to weak interfacial bonding; if only low-temperature sintering is performed, a dense coating layer cannot be formed, resulting in porous aggregates that create defects within the material, leading to a decrease in mechanical strength, thermal shock resistance, and slag resistance, even falling short of the performance of pure corundum particles.

[0129] Function and addition method of interface modifier: The interface modifier (magnesium aluminum spinel precursor sol) generates magnesium aluminum spinel during sintering, filling the interfacial gaps between the ceramic phase, MCR aggregate, and magnesium matrix, gradient regulating thermal expansion, reducing interfacial stress, and improving bonding strength. Without the interface modifier, the interfacial gaps remain, becoming points of thermal stress concentration and channels for slag erosion and penetration. If the interface modifier is replaced with solution A containing only aluminum, complete magnesium aluminum spinel cannot be generated, significantly reducing the interfacial bonding and thermal stress relief effects. If the interface modifier and composite binder are added simultaneously, the binder will preferentially cover the particle surface, hindering the full interaction between the interface modifier and the powder, weakening the interface modification effect, and leading to a decrease in the overall material integrity.

[0130] Each embodiment achieves close particle packing by precisely controlling the particle size distribution of fused magnesia; the microscopic strengthening of composite ceramic powder and the macroscopic support of MCR-reinforced aggregate work synergistically to improve hardness and toughness; the interface modifier improves the interfacial bonding of each phase and reduces internal defects; stepwise high-temperature sintering promotes densification and stable formation of ceramic phase, ultimately achieving balanced optimization of erosion resistance, thermal shock resistance, mechanical strength and slag erosion resistance.

Claims

1. An erosion-resistant ceramic composite magnesium-based refractory material, characterized in that, The raw materials include the following parts by weight: 58 to 62 parts of fused magnesia, 5 to 8 parts of composite ceramic powder, 5 to 7 parts of MCR reinforced aggregate, 1.5 to 2.5 parts of sintering aid, 2.5 to 3.5 parts of interface modifier, 9 to 14 parts of active reinforcing component, and 5 to 7 parts of composite binder; The composite ceramic powder is obtained by sintering zirconium dioxide powder with urea to obtain pre-nitrided ZrO2, which is then ball-milled with nano-titanium powder, micron-sized silicon powder, boric acid, carbon black, calcium fluoride and polyethylene glycol in anhydrous ethanol and sintered. The MCR-reinforced aggregate is obtained by coating corundum particles with sol, sintering them sequentially at 500℃~550℃ and 1250℃~1350℃ to obtain a primary coating material, followed by coating with slurry, and sintering them sequentially at 500℃~550℃ and 1550℃~1650℃. The sol is prepared from Mg(NO3)2·6H2O, Al(NO3)3·9H2O and citric acid. The slurry is prepared from lightly calcined magnesium oxide powder, polymethyl methacrylate and PVB ethanol solution. The interface modifier is a magnesium aluminum spinel precursor sol, which is prepared by reacting aluminum triacetylacetonate with acetylacetonate in anhydrous ethanol to obtain solution A, dissolving Mg(NO3)2·6H2O in ethylene glycol monomethyl ether to obtain solution B, mixing solution A and solution B, adding deionized water to react, and concentrating to a solid content of 20wt% to 25wt%. The sintering aid is a Y2O3-La2O3 composite rare earth oxide; the active enhancement component includes alumina and silicon powder; the composite binder includes aluminum dihydrogen phosphate solution and silane coupling agent KH-550.

2. The erosion-resistant ceramic composite magnesium-based refractory material according to claim 1, characterized in that, The preparation method of the composite ceramic powder includes the following steps: micron-sized silicon powder: nano-sized titanium powder: zirconium dioxide powder: boric acid: urea: carbon black: calcium fluoride: polyethylene glycol in a mass ratio of (28-32): (23-27): (18-22): (5-7): (8-12): (10-14): (1-2): (0.4-0.6); zirconium dioxide powder and urea are mixed and heated to 650℃-700℃ under an ammonia atmosphere and held for 2-3 hours to obtain pre-nitrided ZrO2; the pre-nitrided ZrO2, nano-sized titanium powder, and micron-sized silicon powder are then combined. Boric acid, carbon black, calcium fluoride, and polyethylene glycol are mixed to obtain a mixture. Anhydrous ethanol is added, and the mixture is wet-milled to obtain a slurry. The slurry is dried into blocks, broken up, and passed through an 80-100 mesh sieve to obtain a precursor material. The precursor material is sintered under a nitrogen atmosphere, heated to 500-600℃ and held for 1-1.5 hours, then heated to 1200-1300℃ and held for 1.5-2 hours, then heated to 1550-1650℃ and held for 2-3 hours. The mixture is then cooled in the furnace, pulverized, and passed through a 2000-2500 mesh sieve to obtain composite ceramic powder.

3. The erosion-resistant ceramic composite magnesium-based refractory material according to claim 2, characterized in that, The amount of anhydrous ethanol used is 1.2 to 1.5 times the mass of the mixture; the wet ball milling time is 4 to 6 hours; the precursor material is loaded into a covered graphite crucible, compacted, and the lid has small holes for gas exchange; the median particle size of the micron-sized silicon powder is 5 μm to 10 μm; the median particle size of the nano-titanium powder is 50 nm to 100 nm; the median particle size of the zirconium dioxide powder is ≤1 μm; the median particle size of the boric acid is ≤2 μm; the median particle size of the urea is ≤5 μm; the median particle size of the carbon black is ≤0.3 μm; the median particle size of the calcium fluoride is 2 μm to 5 μm; and the number average molecular weight of the polyethylene glycol is 2000.

4. The erosion-resistant ceramic composite magnesium-based refractory material according to claim 1, characterized in that, The preparation method of the MCR-reinforced aggregate includes the following steps: Mg(NO3)2·6H2O and Al(NO3)3·9H2O are mixed at a mass ratio of 1:(1.4-1.5) to obtain a mixed salt; a 20wt%-25wt% mixed salt solution is prepared with water; 8%-12% of citric acid by mass of the mixed salt is added and stirred to obtain a sol; the sol and corundum particles are mixed evenly at a mass ratio of 1:(4-6), dried, and heated to 500℃-550℃ in air atmosphere and held for 1-1.5 hours; then heated to 1250℃-1350℃ and held for 2 hours. After 3 hours, a primary coating material is obtained. Lightly calcined magnesium oxide powder and polymethyl methacrylate are mixed at a mass ratio of (8-10):1 to obtain a mixture. 15%-20% of the mass of the mixture is added to a PVB ethanol solution, and the mixture is ball-milled to obtain a slurry. The slurry and the primary coating material are mixed evenly at a mass ratio of 1:(5-7), dried, and sintered under a flowing nitrogen atmosphere. The temperature is raised to 500℃-550℃ and held for 1-1.5 hours. The temperature is then raised to 1550℃-1650℃ and held for 2-3 hours. After cooling, MCR reinforced aggregate with a particle size range of 0.3mm-2.2mm is obtained.

5. The erosion-resistant ceramic composite magnesium-based refractory material according to claim 4, characterized in that, The corundum particles are preheated to 200℃~250℃ and held for 20min~30min, then cooled before use; the stirring is carried out at 75℃~85℃ and 150r / min~250r / min for 20min~40min; the particle size range of the corundum particles is 0.5mm~2.0mm; the median particle size of the lightly calcined magnesium oxide powder is 0.8μm~2μm; the median particle size of the polymethyl methacrylate is 5μm~10μm; and the concentration of the PVB ethanol solution is 10wt%~15wt%.

6. The erosion-resistant ceramic composite magnesium-based refractory material according to claim 1, characterized in that, The preparation method of the Y2O3-La2O3 composite rare earth oxide includes the following steps: Y(NO3)3·6H2O and La(NO3)3·6H2O are mixed in a mass ratio of (1~1.5):1 to obtain a mixed salt. A 15wt%~20wt% mixed salt solution is prepared with water. Citric acid of 10%~15% of the mass of the mixed salt is added, stirred, and the pH is adjusted to 8.5~9.

5. The mixture is stirred and allowed to stand to precipitate. The precipitate is washed with deionized water and anhydrous ethanol, dried, sintered in air atmosphere, heated to 500℃~550℃ and held for 1h~2h, heated to 850℃~950℃ and held for 3h~4h, cooled, dry ball milled, and passed through a 3500-4000 mesh sieve to obtain the Y2O3-La2O3 composite rare earth oxide.

7. The erosion-resistant ceramic composite magnesium-based refractory material according to claim 1, characterized in that, The preparation method of the magnesium-aluminum spinel precursor sol includes the following steps: Aluminum triacetylacetonate and acetylacetonate are mixed at a mass ratio of 1:(0.5-0.6), and dissolved in anhydrous ethanol at a mass ratio of 1:(3-3.5). The mixture is refluxed at 70℃-75℃ for 2-2.5 hours, then cooled to 60℃-65℃ to obtain solution A; 38%-42% of the mass of aluminum triacetylacetonate in Mg(NO3)2·6H2O is taken, and the mixture is dissolved in anhydrous ethanol at a mass ratio of 1:(3-3.5). Dissolve 1:(3~3.5) in ethylene glycol monomethyl ether to obtain solution B; add solution B dropwise to solution A under stirring at 60℃~65℃ and 300r / min~400r / min. After the addition is complete, add 30%~35% of deionized water by mass of aluminum triacetylacetonate, and stir the reaction at 60℃~65℃ for 24h~28h. Concentrate under reduced pressure to a solid content of 20wt%~25wt% to obtain magnesium aluminum spinel precursor sol.

8. The erosion-resistant ceramic composite magnesium-based refractory material according to claim 1, characterized in that, The particle size distribution of the fused magnesia is as follows: 3mm < particle size ≤ 5mm accounts for 20wt%–25wt%, 1mm < particle size ≤ 3mm accounts for 30wt%–35wt%, 0.074mm < particle size ≤ 1mm accounts for 30wt%–35wt%, and particle size ≤ 0.074mm accounts for 10wt%–15wt%. The active reinforcing component includes alumina and silicon powder in a mass ratio of (6–8):(3–5); the median particle size of the alumina is 0.8μm–2μm; the median particle size of the silicon powder is 2μm–6μm; the composite binder includes aluminum dihydrogen phosphate solution and silane coupling agent KH-550 in a mass ratio of (3.5–4):1; the density of the aluminum dihydrogen phosphate solution is 1.35 g / cm³. 3 ~1.40g / cm 3 .

9. The method for preparing an erosion-resistant ceramic composite magnesium-based refractory material according to claim 1, characterized in that, Includes the following steps: S1: According to the mass fractions, the composite ceramic powder, MCR reinforced aggregate, sintering aid, active reinforcing component and fused magnesia with a particle size ≤0.074mm are dry-mixed evenly; the interface modifier is added and wet-mixed evenly; the remaining fused magnesia with the specified particle size is added and mixed evenly; finally, the composite binder is added and mixed evenly to obtain the billet. S2: The billet is pressed into shape to obtain a blank; S3: The green body is dried, sintered in a nitrogen atmosphere, heated to 550℃~600℃ and held for 1h~1.5h, heated to 1300℃~1350℃ and held for 2h~2.5h, heated to 1500℃~1550℃ and held for 3h~4h, and then cooled in the furnace to obtain the molded body.

10. The method for preparing an erosion-resistant ceramic composite magnesium-based refractory material according to claim 9, characterized in that, In step S2, the billet is pressed into shape in one step under a pressure of 180MPa to 200MPa, and the pressure is held for 60 to 90 seconds to obtain a density of 3.00 g / cm³. 3 The above-mentioned green body; in S3, the green body is dried at room temperature for 20h to 26h, at 75℃ to 85℃ for 3h to 4h, and at 110℃ to 130℃ for 7h to 9h.

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