Study On Composition,Structure And Properties Of ρ-AL₂O₃ Bonded Alumina-Magnesia Castable

At first, the rheological behaviors of ρ-Al2O3 bonded Alumina-magnesia suspension was studied in this paper. The effect of dispersing agents and composition on rheological behaviors was studied by means of rotary viscosimetor. The result shows the suspension's rheological behaviors is approximately as same as pseudoplastic fluid's, the viscosity of suspension increases with increasing of ρ-Al2O3 ultra fine powder or microsilica content and decrease with the increasing of magnesia powder. Adding 0.3wt% hexametaphosphate as dispersing agent, the matrix of Alumina-Magnesia castable bonded by ρ-Al2O3 ultra fine powder may obtain the optimum flowabiliry.Secondly, the reaction between ρ-Al2O3 ultra fine and magnesia powder was studied. The influence of temperature and hydration on it was studied by means of X-Ray diffraction analysis(XRD), so did the phase at different temperature. The result shows the reaction activity of ρ-Al2O3 ultra fine powder after hydration is higher than that before hydration, because ρ-Al2O3 ultra fine powder after hydration transform to -Al2O3 earlier than that before. After 1600 C sintering for 3 hours, the matrix of Alumina-Magnesia castable bonded by ρ-Al2O3 ultra fine powder main is spinel.At last, the influence of composition on microstructure and properties of ρ-Al2O3 bonded Alumina-Magnesia castable was studied. The effect of ρ-Al2O3/a-Al2O3 ratio, magnesia powder and microsilica addition on properties, slag resistance of Alumina-magnesia castable was studied by scanning electronic microscope (SEM) and energy dispersive spectrum analysis (EDS), and the mechanism of slag corrosion was analyzed. It is found that the matrix compositions, such as ρ-Al2O3/a-Al2O3 ratio, magnesia powder and microsilica addition, have noticeable influence on the properties of Alumina-Magnesia castable bonded by ρ-Al2O3 ultra fine powder.