High Alumina Castables: Effect of Alumina Sols and Distribution Coefficients

Abstract

Two different alumina sols were prepared using different precursor sources and the sols were solely used as binder in no cement high alumina castable. The sols were characterized for their solid content, pH, particle size, zeta potential, thermal behaviour through DSC-TG, phase formation on calcination, etc. The sols were used as sole binder in high alumina castables with different particle size distribution, as per Dinger and Funk model, to attain different flow consistency. The castables were processed conventionally and heat treated at three different temperatures. Different physical and mechanical properties were evaluated and compared. Sol prepared from nitrate precursor resulted in better properties when used as binder in castables as compared to that prepared from commercially available boehmite powder. No deformation in the castables was observed on firing at 1650oC, much above the application temperature of any cement/ sol bonded castables. Absence of any component other than alumina nullifies any eutectic or liquid phase formation in the system.