Fabrication and characterization of lightweight microporous alumina with guaranteed slag resistance

Low thermal conductivity and high mechanical strength and slag resistance are usually mutually exclusive properties. In this study, by introducing a superplastic nanoalumina sol, we fabricated micro porous alumina by wet milling and investigated its properties. The microporous alumina exhibited a low bulk density and apparent porosity as well as high closed porosity and small median pore diameter. The thermal conductivity of the microporous alumina at 800 degrees C was 6.5 W m(-1) K-1, which is 41.6% lower than that of tabular alumina. Furthermore, a more continuous, and thicker (100-200 mu m) Ca(Al,Fe)(12)O-19 (CAF) and Ca(AI,Fe)(4)O-7 (CAF(2)) layer was observed at the microporous alumina/slag interface in comparison to the 30-50 mu m-thick layer usually observed at the tabular alumina/slag interface. The dense continuous isolation layer formed in situ effectively prevented further slag corrosion and penetration. Hence, the microporous alumina exhibited better slag resistance than tabular alumina. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.