Microstructures and strengths of microporous MgO‐Al <sub>2</sub> O <sub>3</sub> refractory aggregates using two types of magnesite
Yifan Huang, Zhe Chen, Wen Yan, Yajie Dai, Guangqiang Li, Qiang Wang, Nan Li, Yawei Li
Abstract
Abstract Six microporous MgO‐Al 2 O 3 refractory aggregates were prepared with Al(OH) 3 and two different types of magnesite powders via an in‐situ decomposition pore‐forming technique. One magnesite powder contained more CaO (Magnesite C), the other one contained more SiO 2 and Al 2 O 3 impurities (Magnesite SA). Effects of magnesite powder type and content (11 wt.%, 36 wt.% and 77 wt.%) on the phase compositions, microstructures and mechanical strengths of the prepared microporous aggregates were investigated by X‐ray diffractometry (XRD), mercury porosimetry measurements, and scanning electron microscopy (SEM), etc. With the addition of 11 wt.% and 77 wt.% magnesite, the type of magnesite had only a small effect on the microporous corundum‐spinel and periclase‐spinel aggregates, while great influence on the microporous spinel aggregates was observed with 36 wt.% addition. This was mainly because of the sintering process with liquid phase. The best microporous MgO‐Al 2 O 3 refractory aggregates, which had an apparent porosity of 39.1%, a median pore size of 3.38 μm and a compressive strength of 66.3 MPa, were prepared by using 36 wt.% Magnesite C. This work has practical significance for the efficient utilization of magnesite and the development of energy‐saving lightweight MgO‐Al 2 O 3 refractories.