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<p>Microporous MgO–MgAl<sub>2</sub>O<sub>4</sub> refractory aggregates were prepared using calcined MgO powder and α-Al<sub>2</sub>O<sub>3</sub> micro-powder as raw materials. The influence of α-Al<sub>2</sub>O<sub>3</sub> micro-powder addition on the microstructures and properties of the aggregates was investigated. The results indicated that the addition of α-Al<sub>2</sub>O<sub>3</sub> micro-powder to MgO powder not only promoted more pores in the MgO powder to being enclosed, but also caused the pores among the MgO powder to become micronano scale by the formation of continuous microporous MgAl<sub>2</sub>O<sub>4</sub> bonding layers, which reduced the thermal conductivity of the aggregates. Furthermore, the microporous MgAl<sub>2</sub>O<sub>4</sub> can induce crack deflection and generate crack branching when subjected to thermal shock, thus improving the thermal shock resistance of the microporous aggregates. The sample with 12.1&#xa0;wt.% α-Al<sub>2</sub>O<sub>3</sub> micro-powder addition exhibited the best comprehensive properties, with a bulk density of 3.44&#xa0;g/cm<sup>3</sup>, a median pore size of 120.7&#xa0;nm, a high flexural strength of 82.7&#xa0;MPa, a high retention rate of flexural strength of 87.7%, and a thermal conductivity of 8.4&#xa0;W/(m K) at 800&#xa0;°C. Compared to commercial fused magnesia and sintered magnesia, the thermal conductivity decreased by 47.2% and 18.4% at 800&#xa0;°C, respectively.</p>

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Enhanced thermal shock resistance of microporous MgO–MgAl2O4 refractory aggregates with low thermal conductivity from MgO powder and α-Al2O3 micro-powder

  • 期刊论文

  • 发表日期：

    2025年8月7日

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  • Jin-ling Shi,
  • Wen Yan,
  • Jun-jie Yan,
  • Shao-song Hong

摘要

Microporous MgO–MgAl2O4 refractory aggregates were prepared using calcined MgO powder and α-Al2O3 micro-powder as raw materials. The influence of α-Al2O3 micro-powder addition on the microstructures and properties of the aggregates was investigated. The results indicated that the addition of α-Al2O3 micro-powder to MgO powder not only promoted more pores in the MgO powder to being enclosed, but also caused the pores among the MgO powder to become micronano scale by the formation of continuous microporous MgAl2O4 bonding layers, which reduced the thermal conductivity of the aggregates. Furthermore, the microporous MgAl2O4 can induce crack deflection and generate crack branching when subjected to thermal shock, thus improving the thermal shock resistance of the microporous aggregates. The sample with 12.1 wt.% α-Al2O3 micro-powder addition exhibited the best comprehensive properties, with a bulk density of 3.44 g/cm3, a median pore size of 120.7 nm, a high flexural strength of 82.7 MPa, a high retention rate of flexural strength of 87.7%, and a thermal conductivity of 8.4 W/(m K) at 800 °C. Compared to commercial fused magnesia and sintered magnesia, the thermal conductivity decreased by 47.2% and 18.4% at 800 °C, respectively.