4.7 Article

Characterisation and properties of low-conductivity microporous magnesia based aggregates with in-situ intergranular spinel phases

期刊

CERAMICS INTERNATIONAL
卷 47, 期 8, 页码 11063-11071

出版社

ELSEVIER SCI LTD
DOI: 10.1016/j.ceramint.2020.12.229

关键词

Microporous magnesia; Intergranular spinel; Thermal conductivity; Thermal shock resistance; Closed pores

资金

  1. National Natural Science Foundation of China [U1908227, U1860205]
  2. Special Project of Central Government for Local Science and Technology Development of Hubei Province [2019ZYYD076]
  3. China Postdoctoral Science Foundation [2019M662731, 2018T110811]
  4. National Key R&D Program of China [2017YFB0310701]

向作者/读者索取更多资源

Development of microporous magnesia-based aggregates at high temperature can enhance ceramic bonding, thermal conductivity, and thermal shock resistance, with pore size distribution being the main factor affecting thermal conductivity.
Development of microporous magnesia based aggregates serving as working-line refractories have great significance in reducing energy loss and saving resource. Microporous magnesia-based aggregates were fabricated at 1780 degrees C by in-situ decomposition of magnesite with addition of nano-sized Al2O3. Intergranular MgAl2O4 phases formed in situ decreased the closed-pore size, thermal conductivity and improved the ceramic bonding and thermal shock resistance. Furthermore, the results suggested that pore size distribution was the dominate factor affecting thermal conductivity. Thermal contact resistance owing to networks of intergranular spinel in magnesia could improve thermal insulation performance effectively. The mismatch of thermal expansion coefficient between spinel and magnesia and the micro-scale closed pores enhanced thermal shock resistance by accommodating thermal stress and suppressing crack propagation. Microporous magnesia-based aggregates with 3 wt% nano-sized Al2O3 presented a mean pore size of 3.42 mu m, thermal conductivity of 5.76 W m(-1) k(-1) (800 degrees C), a cold compressive strength of similar to 285 MPa, and a residual strength retention rate of 65.0% after thermal shock cycles. The low-conductivity microporous magnesia-based aggregates with excellent thermal shock resistance show promise for future application in working-lining lightweight refractories.

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