Alumina-based refractory ceramic composite material and preparation method thereof

Abstract

The invention relates to the technical field of ceramic-based composite material preparation, in particular to an aluminum oxide-based refractory ceramic composite material and a preparation method thereof.The aluminum oxide-based refractory ceramic composite material is prepared from, by mass, 80-90 parts of modified aluminum oxide, 5-10 parts of modified nano zirconium oxide suspension liquid and 3-5 parts of nano titanium dioxide sol, according to the invention, material component modification, interface structure design and gradient protection technology are optimized, compatibility of a matrix and a reinforced phase is cooperatively regulated and controlled, and low-temperature presintering and surface functionalization treatment technologies are improved, so that thermal shock resistance stability, high-temperature strength retention rate and chemical erosion resistance of the material are improved; the refractory material has excellent durability, provides a new solution for high-performance and engineering application of the refractory material, and has a wide application prospect.

Description

Technical Field

[0001] This invention relates to the field of ceramic matrix composite material preparation technology, and in particular to an alumina-based refractory ceramic composite material and its preparation method. Background Technology

[0002] Refractory ceramic composites are multiphase systems composed of ceramic matrices such as oxides, carbides, and nitrides and reinforcing phases such as fibers, particles, and whiskers through specific processes. They are designed for extreme high-temperature, chemical corrosion, and mechanical impact environments. Their core feature is that through the synergistic effect of material components, they break through the performance bottleneck of single ceramics and achieve a comprehensive improvement in high-temperature strength, thermal shock resistance, corrosion resistance, and durability.

[0003] In existing technologies, traditional materials have poor thermal shock resistance due to weak bonding between the matrix and the reinforcing phase interface. The prepared materials are prone to cracking, and at high temperatures, the grain boundaries of the materials soften, causing a sharp drop in strength. At the same time, the preparation of traditional materials mostly relies on high-temperature sintering, which easily leads to particle agglomeration and uneven dispersion. In addition, the energy consumption required for high-temperature sintering is large, which increases the preparation cost of the materials.

[0004] Therefore, based on the relevant technologies mentioned above, there is an urgent need to develop an alumina-based refractory ceramic composite material and its preparation method. Summary of the Invention

[0005] In view of this, the purpose of this invention is to propose an alumina-based refractory ceramic composite material and its preparation method, so as to solve the problems of poor thermal shock resistance, low strength at high temperature and high energy consumption in the prior art.

[0006] To achieve the above objectives, the present invention provides an alumina-based refractory ceramic composite material and its preparation method.

[0007] An alumina-based refractory ceramic composite material, characterized in that it is prepared from the following components in parts by weight: 80-90 parts modified alumina, 5-10 parts modified nano-zirconia suspension, 3-5 parts nano-titanium dioxide sol, 0.5-1 parts fluorosilane solution, 1-2 parts sintering aid, and 0.5-1 parts dispersant polyethylene glycol 400.

[0008] The modified alumina is N-isopropylacrylamide modified alumina;

[0009] The modified nano-zirconia suspension is modified polyacrylate phosphate grafted nano-zirconia.

[0010] Preferably, the preparation steps of the modified alumina are as follows:

[0011] Step A1: Place the alumina powder in a muffle furnace, heat it to 380-420℃, calcine it for 100-140 minutes, cool it, and obtain the treated alumina powder.

[0012] Step A2: Under a nitrogen atmosphere, add the treated alumina powder to an ethanol solvent, sonicate for 20-40 min at a power of 200-400 W, add N-isopropylacrylamide and the initiator azobisisobutyronitrile, sonicate for 8-12 min, stir until homogeneous, heat to 50-70℃, react for 5-7 h, centrifuge, wash, and dry to obtain modified alumina.

[0013] Preferably, the mass ratio of the treated alumina powder, N-isopropylacrylamide, and initiator azobisisobutyronitrile in step A2 is 80-90:0.5-2:0.1-0.3;

[0014] Modifying alumina with N-isopropylacrylamide can form a flexible interface layer, which can alleviate stress concentration caused by the difference in thermal expansion coefficients. After grafting nano-zirconia with polyacrylate phosphate, the phosphate groups react with the hydroxyl groups on the alumina surface to form chemical bonds, which enhances the interfacial bonding. At the same time, the phase transformation toughening of nano-zirconia can absorb crack propagation energy. Through the synergistic effect of the two, the interfacial bonding between the matrix and the reinforcing phase can be optimized, reducing the risk of microcracks caused by the difference in thermal expansion coefficients.

[0015] Preferably, the preparation steps of the modified nano-zirconia suspension are as follows:

[0016] Add nano-zirconia and modified polyacrylate phosphate to deionized water, stir for 13-17 min at 800-1000 rpm, add ammonia water, adjust the pH to 8.0-9.0, heat to 30-40℃, sonicate for 20-40 min at 300-400W, centrifuge to remove impurities, and obtain modified nano-zirconia suspension.

[0017] Setting the reaction temperature to 30-40℃ can prevent the decomposition of polyacrylate phosphate, while promoting the chemical reaction between the modifier and the surface of nano-zirconia, improving the fluidity of the dispersion medium, and enhancing the particle dispersion effect.

[0018] Preferably, the mass ratio of the nano-zirconia to the modified polyacrylate phosphate is 3-5:1.

[0019] Preferably, the preparation steps of the modified polyacrylate phosphate are as follows:

[0020] Under a nitrogen atmosphere, phosphate acrylate, sodium styrene sulfonate, and hexafluorobutyl methacrylate were added to a mixed solution of ethanol and water. The mixture was heated to 35-40°C and stirred for 20-40 minutes. Azobisisobutyronitrile (AIBN) was added as an initiator, and the mixture was stirred for 20-40 minutes at a speed of 700-900 rpm. The mixture was then heated to 60-80°C and reacted for 7-9 hours. The mixture was cooled to 20-30°C, and hydroquinone was added as a polymerization inhibitor. Acetone was added to precipitate the product. The product was then filtered, washed, and dried to obtain modified phosphate acrylate.

[0021] Preferably, the mass ratio of phosphate acrylate, sodium styrene sulfonate, hexafluorobutyl methacrylate, initiator azobisisobutyronitrile, and polymerization inhibitor hydroquinone is 11-13:3-5:2-4:1:0.015-0.025.

[0022] The volume ratio of ethanol to water is 2.3-2.5:1.

[0023] Preferably, the preparation steps of the nano-titanium dioxide sol are as follows:

[0024] Add tetrabutyl titanate to anhydrous ethanol, stir for 8-12 min, add 0.001 mol / L dilute nitric acid, adjust the pH to 2.8-3.2, heat to 25-30℃, stir for 20-25 h at 400-500 rpm, let stand for 50-70 min, filter, and obtain nano titanium dioxide sol.

[0025] The mass ratio of tetrabutyl titanate to anhydrous ethanol is 1:3.8-4.2.

[0026] Preferably, the preparation steps of the fluorosilane solution are as follows:

[0027] Add acetic acid to ethanol solvent, stir for 3-7 min at 400-600 rpm, add heptadecafluorodecyltrimethoxysilane, heat to 23-27℃, stir for 4-6 h, and let stand for 10-14 h to obtain fluorosilane solution.

[0028] The mass ratio of acetic acid, ethanol and heptadecafluorodecyltrimethoxysilane is 0.01:0.02:48-50:1;

[0029] Heptadecafluorodecyltrimethoxysilane can be hydrolyzed to generate fluorosiloxanes. These fluorosiloxanes can form a dense network structure on the substrate, improving the superhydrophobicity of the substrate surface, reducing slag wettability, and simultaneously blocking the penetration of acid and alkali media. During heat treatment, titanium dioxide forms a Si-O-Ti bonded layer with the substrate. Furthermore, under acidic or neutral conditions, the surface of titanium dioxide carries a positive charge, which can prevent the penetration of Ca through electrostatic repulsion. 2+ Fe 3+Plasma penetration, and the fact that titanium dioxide can generate positively charged high-energy reaction sites when exposed to light at high temperatures, thereby decomposing carbon deposits and achieving self-cleaning, together form a chemical-physical synergistic protection.

[0030] A method for preparing an alumina-based refractory ceramic composite material, comprising the following steps:

[0031] Step S1: Add modified alumina to the modified nano-zirconia suspension, stir for 1-3 hours at 200-400 rpm, add ammonia water, adjust the pH to 6-7, add sodium polyacrylate to obtain slurry;

[0032] Step S2: Add sintering aid MgO-Y2O3 and dispersant polyethylene glycol 400 to the slurry, put it into a ball mill, grind at 200-300 rpm for 22-26 h, and the particle size D50 < 1 μm to obtain a mixed liquid.

[0033] Step S3: Pour the mixed liquid into the plaster mold, let it stand for 20-40 minutes, raise the temperature to 20-30℃, humidity 40-60%, dry for 45-50 hours, pressure 150-250MPa, hold the pressure for 1-3 minutes, raise the temperature to 280-320℃, hold the temperature for 50-70 minutes, introduce argon gas, raise the temperature to 1600-1700℃, hold the temperature for 1-3 hours, cool down, and obtain the green body;

[0034] Step S4: Immerse the green body in nano-titanium dioxide sol for 100-120 seconds, heat to 20-30℃, dry for 30-35 minutes, place in a muffle furnace, heat to 400-600℃, hold for 50-70 minutes, cool down for 20-30℃, place in a fluorosilane solution, react for 8-12 minutes, heat to 70-90℃, dry for 25-35 minutes, then heat to 110-130℃, and heat treat for 1-3 hours to obtain a refractory ceramic composite material.

[0035] The mass ratio of the modified alumina, modified nano-zirconia suspension to sodium polyacrylate is 1:0.1-0.15:0.005-0.015;

[0036] The mass ratio of the sintering aid MgO-Y2O3, the dispersant polyethylene glycol 400, and the slurry is 1:0.4-0.6:95-105;

[0037] The mass ratio of the preform, nano-titanium dioxide sol, and fluorosilane solution is 1:0.3-0.5:0.05-0.1.

[0038] The beneficial effects of this invention are:

[0039] This invention provides an alumina-based refractory ceramic composite material and its preparation method. By optimizing material component modification, interface structure design, and gradient protection processes, this invention synergistically regulates the compatibility between the matrix and the reinforcing phase, and improves low-temperature pre-sintering and surface functionalization technologies. Compared with existing technologies, this invention significantly enhances the material's thermal shock resistance, high-temperature strength retention, and chemical corrosion resistance, while reducing preparation energy consumption and process complexity. This invention exhibits excellent durability and is suitable for high-temperature equipment in the metallurgical industry, chemical reactors, and key components in the energy sector. It has advantages such as strong process adaptability and controllable cost, providing a new solution for the high-performance and engineering applications of refractory materials. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0041] Example 1: The preparation steps of modified alumina are as follows:

[0042] S1: Place 800g of alumina powder in a muffle furnace, heat to 380℃, calcine for 140min, cool, and obtain the treated alumina powder;

[0043] S2: Under a nitrogen atmosphere, 800g of treated alumina powder was added to 1000mL of ethanol solvent, sonicated for 20min at 400w, 5g of N-isopropylacrylamide and 1g of initiator azobisisobutyronitrile were added, sonicated for 8min, stirred evenly, heated to 70℃, reacted for 5h, centrifuged, washed, and dried to obtain modified alumina.

[0044] Example 2: The preparation steps of modified alumina are as follows:

[0045] S1: Place 850g of alumina powder in a muffle furnace, heat to 400℃, calcine for 120min, cool, and obtain the treated alumina powder;

[0046] S2: Under a nitrogen atmosphere, 850g of the treated alumina powder was added to 1000mL of ethanol solvent, sonicated for 30min at 300w, 10g of N-isopropylacrylamide and 2g of initiator azobisisobutyronitrile were added, sonicated for 10min, stirred evenly, heated to 60℃, reacted for 6h, centrifuged, washed, and dried to obtain modified alumina.

[0047] Example 3: The preparation steps of modified alumina are as follows:

[0048] S1: Place 900g of alumina powder in a muffle furnace, heat to 420℃, calcine for 100min, cool, and obtain the treated alumina powder;

[0049] S2: Under a nitrogen atmosphere, 900g of the treated alumina powder was added to 1000mL of ethanol solvent, sonicated for 40min at 200w, 20g of N-isopropylacrylamide and 3g of initiator azobisisobutyronitrile were added, sonicated for 12min, stirred until homogeneous, heated to 50℃, reacted for 7h, centrifuged, washed, and dried to obtain modified alumina.

[0050] Example 4: The preparation steps of the modified nano-zirconia suspension are as follows:

[0051] Add 300g of nano-zirconia and 100g of modified polyacrylate phosphate to 500mL of deionized water, stir for 13min at 1000rpm, add ammonia water, adjust the pH to 8.0-9.0, heat to 30℃, sonicate for 40min at 300W, centrifuge to remove impurities, and obtain modified nano-zirconia suspension.

[0052] Example 5: The preparation steps of the modified nano-zirconia suspension are as follows:

[0053] Add 400g of nano-zirconia and 100g of modified polyacrylate phosphate to 500mL of deionized water, stir for 15min at 900rpm, add ammonia water, adjust the pH to 8.0-9.0, heat to 35℃, sonicate for 30min at 350W, centrifuge to remove impurities, and obtain modified nano-zirconia suspension.

[0054] Example 6: The preparation steps of the modified nano-zirconia suspension are as follows:

[0055] Add 500g of nano-zirconia and 100g of modified polyacrylate phosphate to 600mL of deionized water, stir for 17min at 800rpm, add ammonia water, adjust the pH to 8.0-9.0, heat to 40℃, sonicate for 20min at 400W, centrifuge to remove impurities, and obtain modified nano-zirconia suspension.

[0056] Example 7: The preparation steps of modified polyacrylate phosphate are as follows:

[0057] Under a nitrogen atmosphere, 110 g of phosphate acrylate, 30 g of sodium styrene sulfonate, and 20 g of hexafluorobutyl methacrylate were added to a mixed solution of 230 mL of ethanol and 100 mL of water. The mixture was heated to 35 °C and stirred for 40 min. Then, 10 g of the initiator azobisisobutyronitrile was added, and the mixture was stirred for 20 min at a speed of 900 rpm. The mixture was then heated to 60 °C and reacted for 9 h. The mixture was cooled to 20 °C, and 0.15 g of the polymerization inhibitor hydroquinone was added. The mixture precipitated with acetone, was filtered, washed, and dried to obtain modified phosphate acrylate.

[0058] Example 8: The preparation steps of modified polyacrylate phosphate are as follows:

[0059] Under a nitrogen atmosphere, 120g of phosphate acrylate, 40g of sodium styrene sulfonate, and 30g of hexafluorobutyl methacrylate were added to a mixed solution of 240mL of ethanol and 100mL of water. The mixture was heated to 37°C and stirred for 30min. Then, 10g of the initiator azobisisobutyronitrile was added, and the mixture was stirred for 30min at 800rpm. The mixture was then heated to 70°C and reacted for 8h. The mixture was cooled to 25°C, and 0.2g of the polymerization inhibitor hydroquinone was added. The mixture precipitated with acetone, was filtered, washed, and dried to obtain modified phosphate acrylate.

[0060] Example 9: The preparation steps of modified polyacrylate phosphate are as follows:

[0061] Under a nitrogen atmosphere, 130 g of phosphate acrylate, 50 g of sodium styrene sulfonate, and 40 g of hexafluorobutyl methacrylate were added to a mixed solution of 250 mL of ethanol and 100 mL of water. The mixture was heated to 40 °C and stirred for 20 min. Then, 10 g of the initiator azobisisobutyronitrile was added, and the mixture was stirred for 40 min at 700 rpm. The mixture was then heated to 80 °C and reacted for 7 h. The mixture was cooled to 30 °C, and 0.25 g of the polymerization inhibitor hydroquinone was added. The mixture precipitated with acetone, was filtered, washed, and dried to obtain modified phosphate acrylate.

[0062] Example 10: The preparation steps of the nano-titanium dioxide sol are as follows:

[0063] Add 100g of tetrabutyl titanate to 380g of anhydrous ethanol, stir for 8min, add 0.001mol / L dilute nitric acid, adjust the pH to 2.8-3.2, heat to 30℃, stir for 20h at 500rpm, let stand for 50min, filter, and obtain nano titanium dioxide sol.

[0064] Example 11: The preparation steps of the nano-titanium dioxide sol are as follows:

[0065] Add 100g of tetrabutyl titanate to 400g of anhydrous ethanol, stir for 10min, add 0.001mol / L dilute nitric acid, adjust the pH to 2.8-3.2, heat to 27℃, stir for 23h at 450rpm, let stand for 60min, filter, and obtain nano titanium dioxide sol.

[0066] Example 12: The preparation steps of the nano-titanium dioxide sol are as follows:

[0067] Add 100g of tetrabutyl titanate to 420g of anhydrous ethanol, stir for 12min, add 0.001mol / L dilute nitric acid, adjust the pH to 2.8-3.2, heat to 25℃, stir for 25h at 400rpm, let stand for 70min, filter, and obtain nano titanium dioxide sol.

[0068] Example 13: The preparation steps of the fluorosilane solution are as follows:

[0069] Add 0.1g of acetic acid to 480g of ethanol solvent, stir for 3min at 600rpm, add 10g of heptadecafluorodecyltrimethoxysilane, heat to 23℃, stir for 6h, and let stand for 10h to obtain a fluorosilane solution.

[0070] Example 14: The preparation steps of the fluorosilane solution are as follows:

[0071] Add 0.15g of acetic acid to 490g of ethanol solvent, stir for 5min at 500rpm, add 10g of heptadecafluorodecyltrimethoxysilane, heat to 25℃, stir for 5h, and let stand for 12h to obtain a fluorosilane solution.

[0072] Example 15: The preparation steps of the fluorosilane solution are as follows:

[0073] Add 0.2g of acetic acid to 500g of ethanol solvent, stir for 7min at 400rpm, add 10g of heptadecafluorodecyltrimethoxysilane, heat to 27℃, stir for 4h, and let stand for 14h to obtain a fluorosilane solution.

[0074] Example 16: A method for preparing an alumina-based refractory ceramic composite material is as follows:

[0075] S1: Add 100g of modified alumina to 10g of modified nano-zirconia suspension, stir for 1 hour at 400rpm, add ammonia water, adjust the pH to 6-7, add 0.5g of sodium polyacrylate to obtain slurry;

[0076] S2: Add 1g of sintering aid MgO-Y2O3 and 0.4g of dispersant polyethylene glycol 400 to 95g of slurry, put it into a ball mill, grind at 200rpm for 26h, and the particle size D50 < 1μm to obtain a mixed liquid.

[0077] S3: Inject 90g of the mixed liquid into the plaster mold, let stand for 20 minutes, heat to 30℃, humidity 40%, dry for 50 hours, pressure 150MPa, hold for 3 minutes, heat to 280℃, hold for 70 minutes, introduce argon gas, heat to 1600℃, hold for 3 hours, cool down, and obtain the green body.

[0078] S4: Place 10g of the green body into 3g of nano-titanium dioxide sol, immerse for 100s, heat to 30℃, dry for 30min, place in a muffle furnace, heat to 400℃, hold for 50min, cool down by 30℃, place in 0.5g of fluorosilane solution, react for 8min, heat to 90℃, dry for 25min, then heat to 130℃, heat-treat for 1h to obtain refractory ceramic composite material.

[0079] Example 17: A method for preparing an alumina-based refractory ceramic composite material is as follows:

[0080] S1: Add 100g of modified alumina to 12g of modified nano-zirconia suspension, stir for 2 hours at 300rpm, add ammonia water, adjust the pH to 6-7, add 1g of sodium polyacrylate to obtain slurry;

[0081] S2: Add 1g of sintering aid MgO-Y2O3 and 0.5g of dispersant polyethylene glycol 400 to 100g of slurry, put it into a ball mill, grind at 250rpm for 24h, and the particle size D50 < 1μm to obtain a mixed liquid.

[0082] S3: Inject 100g of the mixed liquid into the plaster mold, let stand for 30 minutes, heat to 25℃, humidity 50%, dry for 47 hours, pressure 200MPa, hold for 2 minutes, heat to 300℃, hold for 60 minutes, introduce argon gas, heat to 1650℃, hold for 2 hours, cool down, and obtain the green body.

[0083] S4: Place 100g of the green body into 40g of nano-titanium dioxide sol, immerse for 110s, heat to 25℃, dry for 33min, place in a muffle furnace, heat to 500℃, hold for 60min, cool to 25℃, place in 7g of fluorosilane solution, react for 10min, heat to 80℃, dry for 30min, then heat to 120℃, heat-treat for 2h to obtain refractory ceramic composite material.

[0084] Example 18: A method for preparing an alumina-based refractory ceramic composite material is as follows:

[0085] S1: Add 100g of modified alumina to 15g of modified nano-zirconia suspension, stir for 3 hours at 200rpm, add ammonia water, adjust the pH to 6-7, add 1.5g of sodium polyacrylate to obtain slurry;

[0086] S2: Add 1g of sintering aid MgO-Y2O3 and 0.6g of dispersant polyethylene glycol 400 to 105g of slurry, put it into a ball mill, grind at 300rpm for 22h, and the particle size D50 < 1μm to obtain a mixed liquid.

[0087] S3: Inject 105g of the mixed liquid into the plaster mold, let stand for 40 minutes, heat to 20℃, humidity 60%, dry for 45 hours, pressure 250MPa, hold for 1 minute, heat to 320℃, hold for 50 minutes, introduce argon gas, heat to 1700℃, hold for 1 hour, cool down, and obtain the green body.

[0088] S4: Place 100g of the green body into 50g of nano-titanium dioxide sol, immerse for 120s, heat to 20℃, dry for 35min, place in a muffle furnace, heat to 400℃, hold for 70min, cool down by 20℃, place in 10g of fluorosilane solution, react for 8min, heat to 90℃, dry for 25min, then heat to 130℃, heat-treat for 1h to obtain refractory ceramic composite material.

[0089] Comparative Example 1:

[0090] Compared with Example 16, this comparative example did not omit the fluorosilane solution treatment in the preparation process of the refractory ceramic composite material. All other steps and parameters were the same, and will not be repeated here. The final refractory ceramic composite material was obtained.

[0091] Comparative Example 2:

[0092] This comparative example differs from Example 16 only in that "modified alumina" is replaced with "alumina". All other steps and parameters are the same, and will not be repeated here. The final result is a refractory ceramic composite material.

[0093] Comparative Example 3:

[0094] This comparative example differs from Example 16 only in that “MgO-Y2O3” is replaced with “MgO-Al2O3”. All other steps and parameters are the same, and will not be repeated here. The final result is a refractory ceramic composite material.

[0095] Comparative Example 4:

[0096] Compared with Example 16, this comparative example did not omit the nano-titanium dioxide sol impregnation process in the preparation of the refractory ceramic composite material. All other steps and parameters were the same, and will not be repeated here. The final refractory ceramic composite material was obtained.

[0097] Comparative Example 5:

[0098] Compared with Example 16, this comparative example did not replace the sintering temperature "1600℃" with "1800℃" in the preparation process of the refractory ceramic composite material. All other steps and parameters are the same, and will not be repeated in this comparative example. Finally, the refractory ceramic composite material is obtained.

[0099] Performance testing:

[0100] Thermal shock resistance test:

[0101] Referring to the ASTM C1525-18 test standard, a high-temperature furnace was used. The refractory ceramic composite materials of Examples 16-18 and Comparative Examples 1-5 were cut into 25mm×5mm×3mm pieces, and the surface was polished to Ra<0.1μm. They were then placed in the high-temperature furnace, heated to 1000℃, held for 15min, removed, and placed in 25℃ deionized water. This process was repeated until the materials broke.

[0102] Strength test:

[0103] Referring to the ASTM C1161 testing standard, a universal testing machine and a high-temperature environmental chamber were used. The refractory ceramic composite materials from Examples 16-18 and Comparative Examples 1-5 were cut into 25mm × 5mm × 3mm pieces, polished to Ra < 0.1μm, and placed in the universal testing machine with a span of 20mm. The strength was tested at room temperature (20-30℃). The samples were then placed in the high-temperature environmental chamber under argon atmosphere, heated to 1600℃, and held for 30 minutes. The strength calculation formula is as follows:

[0104]

[0105] F: Fracture load N, L: Span mm, b: Specimen width mm, h: Specimen thickness mm.

[0106] Table 1

[0107]

[0108]

[0109] Slag erosion resistance test:

[0110] The rotary erosion tester was used in accordance with the ASTM C874-19 test standard.

[0111] 1. Slag preparation: Prepare simulated furnace slag according to the mass ratio of CaO:SiO2:Al2O3 of 40:40:20, and grind it to D50 < 50μm;

[0112] 2. Take the refractory ceramic composite materials of Examples 16-18 and Comparative Examples 1-5, cut them into 50mm×50mm×10mm pieces, place them in a crucible with 200g of molten slag, heat to 1600℃, keep at that temperature for 4h, cool down, cut the samples, and measure the erosion depth in mm.

[0113] Wettability test:

[0114] According to the ISO22685:2020 testing standard, a Krüss DSA100 contact angle measuring instrument was used. The refractory ceramic composite materials of Examples 16-18 and Comparative Examples 1-5 were cut into 50mm×50mm×10mm pieces, heated to 1500℃, removed, and molten steel was dropped onto the sample surface. The contact angle was recorded. The process was repeated three times and the average value was taken. A contact angle > 90° was hydrophobic, and a contact angle < 90° was hydrophilic.

[0115] Table 2

[0116]

[0117]

[0118] Density test:

[0119] A density measuring instrument was used in accordance with ASTM B962-17 and ISO 18754:2020 testing standards.

[0120] 1. Take the refractory ceramic composite materials of Examples 16-18 and Comparative Examples 1-5, cut them into 10mm×10mm×5mm pieces, put them in an oven, heat them to 110℃, dry them for 24 hours, cool them to room temperature, and weigh them M1.

[0121] 2. Place the sample in a vacuum impregnation apparatus, vacuum to <1 kPa, maintain for 30 min, add deionized water to submerge, restore to normal pressure, and continue soaking for 4 h. Suspend the sample with a thin metal wire, immerse in water and weigh the saturated suspension weight M2. Remove, wipe off surface moisture with a damp cloth, and weigh the saturated weight M3.

[0122] 3. Calculate the packing density:

[0123]

[0124] Porosity test:

[0125] The test was conducted using a mercury porosimeter, referring to the ISO 15901-1:2016 standard.

[0126] 1. Take the refractory ceramic composite materials of Examples 16-18 and Comparative Examples 1-5, cut them into 5mm×5mm×5mm pieces, put them in an oven, heat them to 110℃, dry them for 24 hours, and place them in a vacuum degassing device. Vacuum them to <<10Pa and degas them for 2 hours.

[0127] 2. Load the sample into the dilatometer, set the pressure range to 0.1-414MPa and pressurize in stages, recording the volume of mercury injected at each pressure point until the maximum pressure is reached;

[0128] 3. Calculate the aperture distribution:

[0129]

[0130] D: Aperture (mm), γ: Mercury surface tension (485 mN / m), θ: Mercury contact angle (140°), P:

[0131]

[0132]

[0133] Table 3

[0134] project Density (%) D Total porosity (%) Example 16 98.5 0.05 1.8 Example 17 98.2 0.06 1.9 Example 18 98.8 0.04 1.7 Comparative Example 1 95.0 0.20 4.5 Comparative Example 2 89.5 0.35 8.2 Comparative Example 3 92.0 0.28 6.5 Comparative Example 4 93.5 0.15 5.0 Comparative Example 5 94.0 0.12 4.2

[0135] Corrosion resistance test

[0136] According to the ASTM G31-21 test standard, the C&W KSL-1200X corrosion test chamber and microhardness tester were used.

[0137] 1. Take 5.0g of each of the refractory ceramic composite materials of Examples 16-18 and Comparative Examples 1-5, place them in a humid atmosphere of RH90% containing 5 vol% SO2, heat to 80°C, and react for 100h.

[0138] 2. Calculate the loss rate:

[0139]

[0140] m0: initial mass (5.0 g); m1: mass after reaction, g.

[0141] Surface hardness test:

[0142] A microhardness tester was used in accordance with the ISO 14924:2020 testing standard.

[0143] Take 5.0g of each of the refractory ceramic composite materials from Examples 16-18 and Comparative Examples 1-5, load them with 500g, hold them under pressure for 15s, and take the average value of 5 points.

[0144] Table 4

[0145] project Weight loss rate (%) Hardness (HV) Example 16 0.3 1800 Example 17 0.2 1820 Example 18 0.4 1780 Comparative Example 1 1.5 1550 Comparative Example 2 2.8 1350 Comparative Example 3 1.2 1600 Comparative Example 4 1.0 1650 Comparative Example 5 1.8 1550

[0146] Data Analysis:

[0147] As can be seen from Tables 1-4, the alumina-based refractory ceramic composite material prepared by the present invention has better thermal shock resistance, high temperature strength, slag erosion resistance, density and corrosion resistance.

[0148] In contrast, Comparative Example 1, by omitting the fluorosilane solution treatment, exhibited enhanced slag wettability, decreased thermal shock resistance, and reduced corrosion resistance. This is because heptadecyltrimethoxysilane hydrolyzes into fluorosiloxanes with a Si-O-Si-F structure, which has a network structure and polar groups, giving the material superhydrophobicity. At the same time, the low thermal conductivity of the fluorocarbon chain can slow down heat transfer efficiency. Furthermore, fluorosiloxanes have a flexible interface with an elastic modulus lower than that of the alumina matrix, which can absorb some thermal stress, thereby improving the thermal shock resistance of the example. In addition, the high CF bond energy can resist the erosion of acid and alkali substances, and its network structure with a pore size of <1nm can block the penetration of small molecules such as SO2 and H2O.

[0149] In Comparative Example 2, replacing modified alumina with alumina resulted in weaker interfacial bonding, increased grain boundary slip, and higher porosity. This is because the modified alumina, through N-isopropylacrylamide grafting, forms a flexible polymer layer that can absorb thermal stress and delay crack propagation. In contrast, the surface of unmodified alumina consists of rigid hydroxyl groups, which cannot provide a buffering effect. Furthermore, during temperature changes, the matrix and the reinforcing phase come into direct contact due to differences in expansion, creating localized stress concentration points at the interface and initiating microcracks. These microcracks propagate rapidly under load, leading to a decrease in room temperature flexural strength. Furthermore, the flexible layer of modified alumina can cover the grain boundaries, inhibiting the migration and slippage of the glass phase. The grain boundaries of unmodified alumina are directly exposed, and the fluidity of the glass phase is enhanced. In Comparative Example 2, due to the lack of a flexible layer, thermal stress cannot be released through interface deformation, resulting in a decrease in the number of thermal shock cycles. In addition, the hydroxyl groups (-OH) on the surface of unmodified alumina are highly polar and easily undergo electrostatic adsorption with nano-zirconia particles, leading to agglomeration. The agglomerates settle faster in the slurry, resulting in a decrease in the stability of the slurry. Therefore, during the sintering process, the agglomerates hinder densification and form closed pores.

[0150] Comparative Example 3, due to the replacement of the sintering aid with MgO-Al2O3, resulted in an increase in grain boundary impurities, insufficient density, and decreased creep resistance. The reason for this was that Y 3+ The ions react with SiO2 impurities in the alumina matrix to generate a high-melting-point Y-Al-Si-O phase, avoiding the formation of a low-melting-point glass phase. Furthermore, Y2O3 promotes grain boundary purification, reduces the enrichment of impurity elements at the grain boundaries, and inhibits high-temperature grain boundary slip. At the same time, Y2O3 promotes grain boundary diffusion by lowering the grain boundary energy, accelerating particle rearrangement and pore removal during the sintering process. In addition, the high-melting-point Y-Al-Si-O phase and the rigid grain boundary structure effectively resist grain boundary slip.

[0151] Comparative Example 4, due to the omission of nano-titanium dioxide sol impregnation, exhibited insufficient corrosion resistance and reduced surface hardness. This is because after impregnation, the nano-titanium dioxide sol reacts with the substrate surface during heat treatment, forming a Si-O-Ti bonded layer. The high chemical stability of TiO2 effectively blocks the flow of Ca in the slag. 2+Fe 3+ Plasma penetration slows down interfacial reactions. At the same time, the dense TiO2 layer can reduce the direct contact area between the slag and the substrate. The high hardness of TiO2 can directly improve the surface compressive strength. In addition, TiO2 can generate positively charged high-energy reaction points under ultraviolet light or high temperature, which can decompose organic matter into CO2 and H2O, reduce the adhesion of surface contaminants, and maintain the long-term performance of the material.

[0152] Comparative Example 5, due to the increase in sintering temperature to 1800℃, resulted in grain coarsening, increased energy consumption and cost, and increased porosity. This is because during ceramic sintering, grain growth is controlled by grain boundary migration rate and diffusion mechanism. At high temperatures, the atomic diffusion coefficient increases significantly, and the grain boundary energy is enhanced, leading to the gradual dissolution of small grains and rapid growth of large grains. At the same time, at 1800℃, the grain boundary migration is too fast, and closed pores are trapped inside the grains, making it difficult for them to be discharged through grain boundary diffusion. Furthermore, the high-temperature energy is used more for grain boundary migration than for pore elimination.

[0153] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

[0154] This invention is intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. An alumina-based refractory ceramic composite material, characterized in that, It is prepared from the following components in parts by weight: 80-90 parts modified alumina, 5-10 parts modified nano-zirconia suspension, 3-5 parts nano-titanium dioxide sol, 0.5-1 parts fluorosilane solution, 1-2 parts sintering aid, and 0.5-1 parts dispersant polyethylene glycol 400. The modified alumina is N-isopropylacrylamide modified alumina; The modified nano-zirconia suspension is modified polyacrylate phosphate grafted nano-zirconia.

2. The alumina-based refractory ceramic composite material according to claim 1, characterized in that, The preparation steps of the modified alumina are as follows: Step A1: Place the alumina powder in a muffle furnace, heat it to 380-420℃, calcine it for 100-140 minutes, and then cool it to obtain the treated alumina powder. Step A2: Under a nitrogen atmosphere, add the treated alumina powder to an ethanol solvent, sonicate for 20-40 min at a power of 200-400 W, add N-isopropylacrylamide and the initiator azobisisobutyronitrile, sonicate for 8-12 min, stir until homogeneous, heat to 50-70℃, react for 5-7 h, centrifuge, wash, and dry to obtain modified alumina.

3. The alumina-based refractory ceramic composite material according to claim 2, characterized in that, The mass ratio of the treated alumina powder, N-isopropylacrylamide, and initiator azobisisobutyronitrile in step A2 is 80-90:0.5-2:0.1-0.

3.

4. The alumina-based refractory ceramic composite material according to claim 1, characterized in that, The preparation steps of the modified nano-zirconia suspension are as follows: Add nano-zirconia and modified polyacrylate phosphate to deionized water, stir for 13-17 min at 800-1000 rpm, add ammonia water, adjust the pH to 8.0-9.0, heat to 30-40℃, sonicate for 20-40 min at 300-400W, centrifuge to remove impurities, and obtain modified nano-zirconia suspension.

5. The alumina-based refractory ceramic composite material according to claim 4, characterized in that, The mass ratio of nano-zirconia to modified polyacrylate phosphate is 3-5:

1.

6. The alumina-based refractory ceramic composite material according to claim 4, characterized in that, The preparation steps of the modified polyacrylate phosphate are as follows: Under a nitrogen atmosphere, phosphate acrylate, sodium styrene sulfonate, and hexafluorobutyl methacrylate were added to a mixed solution of ethanol and water. The mixture was heated to 35-40°C and stirred for 20-40 minutes. Azobisisobutyronitrile (AIBN) was added as an initiator, and the mixture was stirred for 20-40 minutes at a speed of 700-900 rpm. The mixture was then heated to 60-80°C and reacted for 7-9 hours. The mixture was cooled to 20-30°C, and hydroquinone was added as a polymerization inhibitor. Acetone was added to precipitate the product. The product was then filtered, washed, and dried to obtain modified phosphate acrylate.

7. The alumina-based refractory ceramic composite material according to claim 6, characterized in that, The mass ratio of phosphate acrylate, sodium styrene sulfonate, hexafluorobutyl methacrylate, initiator azobisisobutyronitrile, and polymerization inhibitor hydroquinone is 11-13:3-5:2-4:1:0.015-0.

025. The volume ratio of ethanol to water is 2.3-2.5:

1.

8. The alumina-based refractory ceramic composite material according to claim 1, characterized in that, The preparation steps of the nano-titanium dioxide sol are as follows: Add tetrabutyl titanate to anhydrous ethanol, stir for 8-12 min, add 0.001 mol / L dilute nitric acid, adjust the pH to 2.8-3.2, heat to 25-30℃, stir for 20-25 h at 400-500 rpm, let stand for 50-70 min, filter, and obtain nano titanium dioxide sol. The mass ratio of tetrabutyl titanate to anhydrous ethanol is 1:3.8-4.

2.

9. The alumina-based refractory ceramic composite material according to claim 1, characterized in that, The preparation steps of the fluorosilane solution are as follows: Add acetic acid to ethanol solvent, stir for 3-7 min at 400-600 rpm, add heptadecafluorodecyltrimethoxysilane, heat to 23-27℃, stir for 4-6 h, and let stand for 10-14 h to obtain fluorosilane solution. The mass ratio of acetic acid, ethanol and heptadecafluorodecyltrimethoxysilane is 0.01:0.02:48-50:

1.

10. A method for preparing an alumina-based refractory ceramic composite material according to any one of claims 1-9, characterized in that, The preparation steps are as follows: Step S1: Add modified alumina to the modified nano-zirconia suspension, stir for 1-3 hours at 200-400 rpm, add ammonia water, adjust the pH to 6-7, add sodium polyacrylate to obtain slurry; Step S2: Add sintering aid MgO-Y2O3 and dispersant polyethylene glycol 400 to the slurry, put it into a ball mill, grind at 200-300 rpm for 22-26 h, and the particle size D50 < 1 μm to obtain a mixed liquid. Step S3: Pour the mixed liquid into the plaster mold, let it stand for 20-40 minutes, raise the temperature to 20-30℃, humidity 40-60%, dry for 45-50 hours, pressure 150-250MPa, hold the pressure for 1-3 minutes, raise the temperature to 280-320℃, hold the temperature for 50-70 minutes, introduce argon gas, raise the temperature to 1600-1700℃, hold the temperature for 1-3 hours, cool down, and obtain the green body; Step S4: Immerse the green body in nano-titanium dioxide sol for 100-120 seconds, heat to 20-30℃, dry for 30-35 minutes, place in a muffle furnace, heat to 400-600℃, hold for 50-70 minutes, cool down for 20-30℃, place in a fluorosilane solution, react for 8-12 minutes, heat to 70-90℃, dry for 25-35 minutes, then heat to 110-130℃, and heat treat for 1-3 hours to obtain a refractory ceramic composite material. The mass ratio of the modified alumina, modified nano-zirconia suspension to sodium polyacrylate is 1:0.1-0.15:0.005-0.015; The mass ratio of the sintering aid MgO-Y2O3, the dispersant polyethylene glycol 400, and the slurry is 1:0.4-0.6:95-105; The mass ratio of the preform, nano-titanium dioxide sol, and fluorosilane solution is 1:0.3-0.5:0.05-0.1.

Images