Thermal shock resistance of Al2O3/SiO2 composites by sol-gel

In this paper, the SiO₂ ceramic matrix composites were reinforced by the two-dimensional (2D) braided Al₂O₃ fibers by sol-gel. To develop the high performance aeroengine with excellent resistance to thermal shock for advanced aerospace application, two different thermal shock temperatures (1100?°C and 1300?°C) and three different thermal shock cycles (10, 20 and 30 cycles) were tested and compared in this paper; besides, the thermal shock resistance of Al₂O₃/SiO₂ composites was investigated in air. Our results suggested that, the flexural strength of the untreated composites was 78.157?MPa, while the residual strength of Al₂O₃/SiO₂ composites under diverse thermal shock cycles and temperatures had accounted for about 95% and 50% of the untreated composites, respectively. Meanwhile, the density and porosity of the composites were gradually increased with the increase in test temperature. Moreover, the changes in fracture morphology and micro-structural evolution of the composites were also observed. Our observations indicated that, the fracture morphology of the composites mainly exhibited ductile fracture at the thermal shock temperature of 1100?°C, whereas brittle fracture at the thermal shock temperature of 1300?°C. Additionally, Al₂O₃/SiO₂ composites belonged to the Oxide/Oxide CMCs, so no new phase was formed after thermal shock tests. Above all, findings of this paper showed that Al₂O₃/SiO₂ composites had displayed outstanding thermal shock resistance.     

Design and fabrication of Al2O3f/SiCN composite with excellent microwave absorbing and mechanical properties

A new kind of structural and functional integration ceramic matrix composite material was prepared from high-performance alumina (Al₂O₃) fibers and absorbing silicon carbonitride (SiCN) ceramics via a combination of polymer infiltration pyrolysis (PIP) and chemical vapor infiltration (CVI) methods. The Al₂O₃ fiber annealed at its cracked temperature had enhanced permittivity, because the sizing agent on the Al₂O₃ fiber surface was cracked into pyrolysis carbon. For PIP + CVI Al₂O_3f/SiCN composites, PIP SiCN matrix with low conductivity was used as the matching phase, while CVI SiCN matrix with medium permittivity and dielectric loss was regarded as the reinforcing phase distributed in porous PIP SiCN matrix and inter-bundles of Al₂O₃ fiber to improve their mechanical and microwave absorption properties. The fracture toughness and flexural strength of Al₂O_3f/SiCN composite were determined to be 9.4 ± 0.5 MPa m^1/2 and 279 ± 28 MPa, respectively. Based on the design principles for impedance matching, the Al₂O_3f/SiCN composites before and after oxidation were used as loss and impedance layers, respectively. It was found that the optimized composite had the lowest reflection coefficient (RC) of −70 dB and the effective absorption bandwidth covering the whole X-band. In conclusion, Al₂O_3f/SiCN composite can serve as a high-temperature structural material with excellent microwave absorption properties for aerospace applications.     

Preparation of Al2O3-mullite thermal insulation materials with AlF3 and SiC as aids by microwave sintering

Al₂O₃-mullite composites were prepared under the synergy effect of AlF₃ and SiC aids by microwave heating. The phase composition, microstructure, porosity, flexural strength, thermal shock resistance, and thermal conductivity were investigated. The XRD results revealed that the content of mullite phase steadily increased with the increasing of AlF₃ content. The microstructure showed that the lower content (≤1 wt%) of AlF₃ led to the formation of granular mullite and the higher content (≥3 wt%) of AlF₃ led to the formation of mullite whiskers, which could form an interlocking structure. In addition, the SiC hot spots can also promote the generation of mullite whiskers by microwave sintering. The thermal shock resistance was significantly improved by the interlocking structure of mullite whiskers. The residual rate of flexural strength of the composite with 3 wt% AlF₃ was 86%. The composite with 3 wt% AlF₃ additives got its optimized thermal conductivity from 30°C to 950°C, the value was between 0.819 and 1.021 W/(mK), which possess excellent thermal insulation performance.     

Preparation of Al2O3@CaCO3 aggregates and its effects on the thermal shock resistance of Al2O3-MgO castables

Al₂O₃@CaCO₃ aggregates were prepared by impregnating corundum aggregates (particle sizes with 3-1 and 5-3 mm) in precursor solutions (Calcium hydrogen citrate, CaHC₆H₅O₇) followed by heat treatment at 430°C. The phase composition and microstructure of the coatings were characterized via X-ray diffraction and scanning electron microscope, respectively. The novel aggregates were used in Al₂O₃-MgO castables. The effects of the Al₂O₃@CaCO₃ aggregates on the physical properties and thermal shock resistance (TSR) of castables were investigated. The results show that uniform CaCO₃ coating of aggregates (C15) with thickness about 10 µm can be attained when the concentration of Ca²⁺ in solution was 0.15 mol L⁻¹. There was a strong bonding between the aggregates and coating that was constituted by particles with size about 0.2 µm. Both improving physical and TSR properties of the castables are related with the unique layer structure, calcium hexaluminate (CA₆) layer in-situ formed at the aggregate-matrix interface, of added Al₂O₃@CaCO₃ aggregates. There is a mass of multi-deflection of cracks along with the CA₆ layer which consumes more fracture surface energy. The castables with C15 exhibit optimal TSR and the residual strength ratio after the thermal shock test is 29.5%, which is 12.8% higher than the castables with corundum aggregates.     

Degradation of Al2O3f/SiO2 composites exposed to Na2SO4 environment and MMH/N2O4 bipropellants test

Al₂O_3f/SiO₂ composites were fabricated efficiently using sol-gel process. The degradation behavior exposed to Na₂SO₄ environment at 1100℃ and MMH/N₂O₄ bipropellants test were investigated and compared. The results showed that the strength of Al₂O_3f/SiO₂ composites gradually decreased as the ratio of Na₂SO₄:water increased; the strength of the composites was only 23.56 MPa at 20% (Na₂SO₄:water), which suggested that the composites maintained lower strength. Cracks began to appear in SiO₂ matrix, and the structure of Al₂O₃f/SiO₂ composites could be corroded which would corrode the SiO₂ matrix, leaving naked fibers. Developing a protective layer with higher stability for Al₂O_3f/SiO₂ composites would be considered for long time use. The composites showed higher ablation resistance to MMH/N₂O₄ bipropellant test; the flexural strength was (77.15 ± 4.56) MPa and the retention ratio was 98.7%. The degradation of Al₂O_3f/SiO₂ composites was promoted owing to the thermal-mechanical and chemical factors. SiO₂ matrix became weak and fragile at elevated temperature; some SiO₂ matrix became loosened and porous after being washed away through the shearing of MMH/N₂O₄ bipropellants, which prevented cracks from penetrating Al₂O₃ fibers. With ongoing test, the fibers were worsened by thermal-mechanical corrosion.     

Cyclic thermal shock resistance of h-BN composite ceramics with La2O3–Al2O3–SiO2 addition

The effects of La₂O₃–Al₂O₃–SiO₂ addition on the thermal conductivity, coefficient of thermal expansion (CTE), Young's modulus and cyclic thermal shock resistance of hot-pressed h-BN composite ceramics were investigated. The samples were heated to 1000 °C and then quenched to room temperature with 1–50 cycles, and the residual flexural strength was used to evaluate cyclic thermal shock resistance. h-BN composite ceramics containing 10 vol% La₂O₃–Al₂O₃ and 20 vol% SiO₂ addition exhibited the highest flexural strength, thermal conductivity and relatively low CTE, which were beneficial to the excellent thermal shock resistance. In addition, the viscous amorphous phase of ternary La₂O₃–Al₂O₃–SiO₂ system could accommodate and relax thermal stress contributing to the high thermal shock resistance. Therefore, the residual flexural strength still maintained the value of 234.3 MPa (86.9% of initial strength) after 50 cycles of thermal shock.     

Optimization of corrosion resistance and mechanical properties of Al2O3-Cr2O3 refractories for waste incinerator

The corrosion resistance and mechanical properties directly affects the operation and service life of Al₂O₃-Cr₂O₃ refractories used in waste incinerators. In this study, ZrO₂ particles were introduced via vacuum impregnation to adjust microstructure and properties of Al₂O₃-Cr₂O₃ refractories. The results showed that the impregnated ZrO₂ particles and increasing impregnation times resulted in the decreased median pore size and increased compactness, and mechanical strengths of refractories were elevated from the inhibited cracks propagation by ZrO₂ particles. The decreased amounts of large pores and increased amounts of small pores from the filled ZrO₂ particles inhibited penetration of low melting point phases, and the formed CaZrO₃ phase from the reactions between corrosion reagent and ZrO₂ particles increased the viscosity of penetrated corrosion reagent, resulting in the decreased penetration index from 8.57% to 2.58%. Meanwhile, the filled ZrO₂ particles around alumina particles prevented reactions between molten corrosion reagent and alumina, leading to the decreased corrosion index from 3.78% to .74%. The decreased pore size and formation of CaZrO₃ phase were primary factors that enhanced the penetration resistance. And formation of wrapped layers from ZrO₂ particles around alumina particles presented prominent effects on the strengthened corrosion resistance of Al₂O₃-Cr₂O₃ refractories.     

Microstructure and mechanical properties of CaAl12O19 reinforced Al2O3-Cr2O3 composites

Al₂O₃-Cr₂O₃ refractories have excellent slag corrosion resistance and can adapt to the oxidation/reduction atmosphere in the smelting reduction ironmaking furnace. However, Al₂O₃-Cr₂O₃ refractories have poor mechanical properties and sintering properties. In order to improve the mechanical properties of Al₂O₃-Cr₂O₃ materials, the CaAl₁₂O₁₉ reinforced Al₂O₃-Cr₂O₃ composites were prepared by pressureless sintering process, and the influences of CaO content on the sintering properties, mechanical properties, and microstructure evolution of the composites were studied. The results show that a small amount of CaO can significantly improve the compactness of the composites, which is mainly due to the formed sheet-like CA6 fill the gap between the solid solutions, and reduces the porosity of the composites. In addition, the sheet-like CA6 makes the connection between solid solutions closer, and the intergranular fracture gradually transforms into a mixed mode of intergranular and transgranular fracture. The best mechanical propertie is observed at S4 with the CaO content of 2 wt.%. Compared with sample S0 without CaO, the hardness, compressive strength and flexural strength of the S4 were increased by 35.19 %, 49.69 %, and 68.34 %, respectively. The addition of excessive CaO will deteriorate the mechanical properties of the composites, because the formation of a large number of layered CA6 increases the porosity of the composites. Furthermore, a small amount of CaO addition can significantly improve the thermal shock resistance of the composites. After 10 and 20 thermal shock cycles, the strength loss rates of S4 are only 5.83 % and 8.74 %, respectively.     

Fabrication of Al2O3-coated carbon fiber-reinforced Al-matrix composites

Fine Al₂O₃ coating could be obtained from alumina sols modified by chelator acetylaceton, under exact control of the parameters. Al₂O₃ coating by the sol–gel method on the carbon-fiber (CF) surface was investigated in detail to improve the oxidation resistance of CFs. Further study focused on making the Al₂O₃-coated fiber-reinforced aluminum composite prefabrication. XRD, IR, TG–DTA, and SEM methods were used to analyze the alumina gels, the coated CFs, and the prefabrication. After the coating treatment, the oxidation resistance of the carbon fibers is enhanced, the wetting between the fibers and melting aluminum is greatly improved, and the tensile strength of CF/Al prefabrication is heightened. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 177–183, 1998     

Correlation of microstructure and mechanical properties of Al2O3-C bodies containing Nano-Al2O3 and Nano-TiO2 additives

Al₂O₃-C foam filters have been successfully used for steel and aluminum melts filtration. Improving the high-temperature mechanical properties enhances the capability and application of these filters for the filtration of large steel casting parts along with ingot casting or continuous casting of steel for long periods of time. In this study, adding nano-Al₂O₃ and/or nano-TiO₂ to the composition of Al₂O₃-C filters was investigated. Uniaxially pressed Al₂O₃-C samples containing additives in the range from 0 to 1.0 wt% of nano-oxides were prepared. The physical and mechanical properties, as well as microstructural analysis, were measured after sintering at 1600°C for 5 hours under a petroleum coke bed. The results showed that the presence of nano-Al₂O₃ particles in the composition led to an increase in the cold crushing strength (CCS) due to the formation of the Al₃CON phase which acts as a chemical bonding between Al₂O₃ particles and the carbonaceous matrix. On the other hand, the addition of 1.0 wt% of nano-TiO₂ in the composition caused an increase of 50% in the hot modulus of rupture (HMOR), attributed to the formation of columnar Al₂O₃ grains in the microstructure.     

Reaction mechanisms and properties of in situ porous Al2O3-ZrO2-mullite composites

Customized porous Al₂O₃-ZrO₂-mullite composites were designed and prepared by reaction sintering of zircon (ZrSiO₄) and alumina (Al₂O₃) at sintering temperatures from 1400 to 1600 °C for 3 h. The mechanical properties, microstructural evolution, and reaction mechanisms of the composites were investigated. The reactions between ZrSiO₄ and Al₂O₃ were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectrometer (EDS). The results indicate that ZrSiO₄ and Al₂O₃ react and form ZrO₂ and mullite. Sintering temperature has an important effect on the reaction process. At 1400 °C, Al₂O₃ reacts directly with SiO₂ of ZrSiO₄ to form mullite and ZrO₂, which reduces the decomposition temperature of ZrSiO₄ and promotes the decomposition of ZrSiO₄. However, at 1600 °C, ZrSiO₄ first decomposes to form SiO₂ and ZrO₂, and then generates mullite by the diffusion of Si. The migration of Si is the key factor for the formation of mullite. The thermal shock resistance of the composites can be significantly improved by phase transformation toughening of in-situ ZrO₂. Therefore, increasing the proportion of ZrSiO₄ can significantly improve the mechanical properties of sample. The residual ratio of the flexural strength after thermal shock exceeded 90%, when the mass ratio of ZrSiO₄ to Al₂O₃ was 3:1. Besides, the addition of polymethyl methacrylate could improve the porosity of materials and has a direct effect on the thermal conductivity of composites.     

Glass-ceramics for joining oxide-based ceramic matrix composites (Al2O3f/Al2O3-ZrO2) operating under direct flame exposure

This work focuses on the joining processes of oxide-based ceramic matrix composites (Al₂O_3f /Al₂O₃-ZrO₂), which are used as radiant tube furnace components in the steel industry. These components have to operate in harsh environments, and under high temperatures, and they therefore have to resist corrosion, humidity, and combustion. Two glass-ceramics systems, which have Y₂Ti₂O₇ as their main crystalline phase, as well as specific and optimized properties to withstand severe operating conditions, including temperatures of 900 °C, are here proposed as joining materials. The adhesion of the glass-ceramics to the composite was found to be excellent after mechanical and thermal tests in which they were in direct contact with a 900 °C flame and thermal cycling of between 400 °C and 900 °C.     

Preparation of multilayered C–Si–Al2O3 coatings on continuous carbon fibers and C–Si–Al2O3-coated carbon-fiber-reinforced hydroxyapatite composites

Multilayered C–Si–Al coatings with various morphologies were deposited on carbon fibers (CFs) using magnetron sputtering. The thickness of the coatings was increased from 0.5 to 1.5 μm by magnetron sputtering between 90 and 120 min. C–Si–Al coatings of suitable thickness were heat-treated at 600 °C and transformed into C–Si–Al₂O₃ coatings by one-step anodic oxidation (AO). The oxidation time for the one/two-step anodic oxidation and the ratio of oxidation time for the two-step anodic oxidation significantly influenced the morphologies of the C–Si–Al₂O₃(AO) coatings. Al₂O₃ coatings with satisfactory morphologies and structures were prepared by two-step anodic oxidation with a total time of 30 min and a ratio of 1:1 between the initial and secondary oxidation times. The multilayered C–Si–Al₂O₃(AO) coatings were modified to C–Si–Al₂O₃ coatings by secondary heat treatment at 1050 °C. Subsequently, hot-press sintering was used to prepare CFs with multilayered C–Si–Al₂O₃ coating-reinforced hydroxyapatite (CF/C–Si–Al₂O₃/HA) composites. The multilayered C–Si–Al₂O₃-coated CFs demonstrated good resistance to oxidation and thermal shock. This could effectively protect CFs from oxidative damage and maintain its strengthening effect during sintering. The multilayered C, Si, and Al₂O₃ coatings effectively reduced the difference between the coefficient of thermal expansion of the CFs and HA matrixes. The interfacial gaps between the multilayered coatings and HA were reduced. This could enhance the mechanical performance of the composites. The CF/C–Si–Al₂O₃/HA composites exhibited improved mechanical properties with a bending strength of 83.94 ± 12.29 MPa, and fracture toughness of 2.45 ± 0.08 MPa m^1/2. This study can broaden the application of CF/C–Si–Al₂O₃/HA biocomposites as bone-repair materials and help obtain CF-reinforced composites with excellent mechanical properties that are fabricated or serviced at high temperatures.     

Synthesis of Al2O3-SiC powder from electroceramics waste and its application in low-carbon MgO-C refractories

Composite additives are an efficient means to improve the high-temperature stability and slag resistance of low-carbon MgO-C refractories. In this work, Al₂O₃-SiC powder was firstly synthesized from electroceramics waste by carbon embedded method at 1500°C, 1550°C, and 1600°C for 4 h, and then the as-synthesized Al₂O₃-SiC powder was used as an additive to low-carbon MgO-C refractories. The effects of its addition amounts of 0, 2.5 wt.%, 5.0 wt.%, and 7.5 wt.% on the properties of the refractories were investigated in detail. It was found that increasing the heat treatment temperature is beneficial to the phase conversion of mullite and quartz to alumina and silicon carbide in the electroceramics waste. Furthermore, the addition of Al₂O₃-SiC powder effectively improves the performance of low-carbon MgO-C samples, and the formation of spinel dense layer and high-viscosity isolation layer is the internal reason for the improvement of the oxidation resistance and slag resistance of low-carbon MgO-C samples. This work provides ideas for the reuse of electroceramics waste and presents an alternative strategy for the performance optimization of low-carbon MgO-C refractories.     

Restructuring-diffusion mechanism of calcium alumino-titanate in CaAl12O19–MgAl2O4–Al2O3 castables

Calcium alumino-titanate (CAT), a secondary material obtained from ferrotitanium slag, was used as a hibonite source to prepare CaAl₁₂O₁₉–MgAl₂O₄–Al₂O₃ castables. The restructuring effect of CAT aggregate was compared by replacing tabular alumina aggregates with CAT aggregates of different particle sizes. The effects of CAT particle size on cold mechanical strength and thermal shock resistance of CaAl₁₂O₁₉–MgAl₂O₄–Al₂O₃ castables were studied. The results showed that CAT aggregates with particle size of 5–3 or 3–1 mm led to more internal cracks or pores and reduced the cold mechanical strength of the castable samples fired at 1600 °C for 3 h. The use of CAT aggregates with particle size of 1–0 mm led to the formation of a well-bonded CAT aggregate and matrix, improving the cold mechanical strength and thermal shock resistance of the castable samples fired at 1600 °C for 3 h. The enhancement mechanism of fine CAT aggregates in this process was proposed based on the sintering of the matrix–aggregate interface with the formation of Ca(Al, Mg, Ti)₁₂O₁₉.     

Investigation of preparation and properties of Ti3SiC2/Al2O3 multilayered composites

Ti₃SiC₂/Al₂O₃ multilayered composites were prepared by the combination of tape casting and hot pressing sintering. The slurry was produced by adjusting the amounts of each organic material, including triethyl phosphate (TEP) as a dispersion, polyvinyl butyrate (PVB) as a binder, dioctyl phthalate (DOP) as a plasticizer, and anhydrous ethanol as an organic solvent. When TEP content was 3 wt.%, PVB content was 4.5 wt.%, R-value (DOP/PVB) was 1.4, and solid content was 38 wt.%; the cast film with a smooth surface, good flexibility, and uniform thickness was obtained after defoaming, tape casting, and drying. Three samples were prepared, namely, S1–S3. The S1 was monolithic Ti₃SiC₂/Al₂O₃ (mass ratio is 1:1) composites. S2 and S3 were Ti₃SiC₂/Al₂O₃ multilayered composites, which matrix layers were Ti₃SiC₂/Al₂O₃ composites (mass ratio is 1:1) and Al₂O₃, respectively, and their interface layer was Ti₃SiC₂. S1–S3 were also sintered at 1550°C. The bending strength of multilayered materials were lower than that of monolithic material, but the fracture toughness of multilayered materials significantly increased. Due to the introduction of Ti₃SiC₂ interface layer, the friction coefficient and wear rate of Ti₃SiC₂/Al₂O₃ multilayered composites were reduced by 30.7% and 33.8%, respectively, compared with monolithic material.     

Sintering behavior and morphology control of porous Al2O3-SiO2 ceramics for radome applications

Ceramics from porous Si₃N₄ and its derivatives SiAlON and Si₂N₂O were once considered the most promising high-temperature wave-transmitting materials. However, their large-scale application in the field of radomes is greatly restricted due to their poor oxidation resistance, high preparation costs, and expensive raw materials. Therefore, the development of low-cost porous oxide ceramics remains of significant interest to the field of high-temperature wave transmission. Surprisingly, mullite ceramics, which are representative of the Al₂O₃-SiO₂-system of ceramics, are ultra-low-cost materials with the potential to replace ceramics from Si₃N₄ and its derivatives. In this paper, integrated porous Al₂O₃-SiO₂-system ceramics were successfully prepared for load-bearing/wave-transmitting applications, using inexpensive calcined kaolin and alumina powder as the main raw materials. Calcined kaolin can provide seeds for the growth and development of mullite crystals in the ceramic system. High-strength and high-porosity ceramics were obtained with the mullite morphology controlled through the molar ratio of Al₂O₃ to SiO₂ and the resulting content of mullite seeds. With increasing of mullite seed content, the length and radial width of mullite whiskers with “interlocking structure” gradually change from rod-shaped “long and thick” to needle-like “short and thin.” The prepared porous Al₂O₃-SiO₂ ceramics have high flexural strength, fracture toughness, and good dielectric properties.     

Study on properties of Ca0.9La0.067TiO3-0.01Al2O3 ceramics reinforced PSAE/fiber composite substrate with high εr

A “self-permeation” method was used to fabricate a Ca_0.9La_0.067TiO₃-0.01Al₂O₃ (CLT)-reinforced polysilylaryl-enyne/fiber multilayer board with different volume fractions of CLT (0–40 vol%). The microstructure, dielectric, mechanical, and thermal properties were fully studied. The results showed that the composite with optimal dielectric properties (ε_r∼8.75, tanδ∼0.0043) could be obtained when the volume fraction of CLT reached 30 vol%. Meanwhile, the thermal conductivity reached a high level of 0.644 W/(m·K) and 0.762 W/(m·K) at Z and X/Y directions, respectively. Due to the high decomposition temperature of PSAE, T_d5 (the temperature corresponding to 5% weight loss) of composite loading with 30 vol% CLT was higher than 900℃, which indicates an excellent thermal resistance. And the bending strength could reach 115.3 MPa indicating excellent mechanical property. The novel polysilylaryl-enyne/fiber/Ca_0.9La_0.067TiO₃-0.01Al₂O₃ multilayer board with excellent performance is expected to be a candidate material for print circuit boards and widely used in the microwave communication field.     

High-temperature oxidation behaviour of vacuum hot-pressed WC-15 wt% Al2O3 composites

In this study, WC-15 wt% Al₂O₃ composites were prepared using the vacuum hot-pressing sintering method. The high-temperature (600–800 °C) oxidation behaviour of WC-15 wt% Al₂O₃ composites was investigated and compared with that of WC-6wt.%Co cemented carbides. The results showed that the oxidation resistance of WC-15 wt% Al₂O₃ composites was better than that of WC-6wt.%Co cemented carbides at relatively high temperatures (700–800 °C). At 800 °C, an oxide layer was formed on the surface of WC-15 wt% Al₂O₃ composites, which included WO₃ and Al₂O₃. The dispersion of alumina in the composites hindered the further diffusion of oxygen, thus improving the oxidation resistance. The Arrhenius activation energies of WC-15 wt% Al₂O₃ composites and WC-6wt.%Co cemented carbides were 110 ± 1 kJ/mol and 167 ± 2 kJ/mol at 600–800 °C, respectively.     

Substitution of antioxidant Si by andalusite fine powder in Al2O3-SiC-C castables

Our previous research showed that the addition of andalusite aggregates can enhance the oxidation resistance of Al₂O₃-SiC-C castables; this is attributed to the transformation of andalusite into a silica-rich glass phase that blocks pores. Theoretically, andalusite with a smaller particle size would achieve a higher extent of conversion and generate more silica-rich glass, which would be more conducive to blocking pores. Therefore, this study evaluates the influence of andalusite fine powder on the oxidation resistance of Al₂O₃-SiC-C castables containing a reduced amount of Si antioxidant. The results show that introducing a small amount of andalusite fine powder endows the Al₂O₃-SiC-C castables with significant oxidation resistance so that the traditional addition of Si metal as an antioxidant can be substantially reduced or even completely eliminated. Meanwhile, the thermal shock stability and strength of the castables were also enhanced.