Microstructure and phase evolution of alumina-spinel self-flowing refractory castables containing nano-alumina particles

The microstructure and phase composition of alumina spinel self-flowing refractory castables added with nano-alumina particles at different temperatures are investigated. The physical and mechanical properties of these refractory castables are studied. The results show that the addition of nano-alumina has a great effect on the physical and mechanical properties of these refractory castables. With the increase of nano-alumina content in the castable composition, the mechanical strength is considerably increased at various temperatures. It is shown that nano-alumina particles can affect formed phases after firing. The platy crystals of CA(6) are detected inside the grain boundaries of tabular alumina and spinel grains in samples fired at 1500 degrees C. CA(6) phase can be formed at lower temperatures (1300 degrees C) with the addition of nano-alumina particles. As a result of using nanometer-sized alumina particles with high surface area, the solid phase sintering of the nano-sized particles and CA(6) formation can occur at lower temperatures. (c) 2010 Elsevier Ltd and Techna Group S.r.l. All rights reserved.