RHEOLOGICAL BEHAVIOR AND PROPERTIES OF LOW CEMENT ALUMINA SPINEL CASTABLES HAVING MICRO SILICA

摘要

Rheological behavior of the low cement Alumina Spinel Castables was studied. The effects and influences of microsilica on the mechanical and physical properties of the castable were evaluated and finally, the slag penetration resistance was studied. The samples were formulated and prepared using tubular Alumina, calcined Alumina, Spinel, MgO powder, Microsilica and cement, along with additives. Then, the flowability of the castables was measured by using a vibrating flow table immediately after mixing .After that , the physical and mechanical properties were measured and microstructure and formed phases were studied by SEM and XRD. The data indicated that Bulk density was increased due to the increase in microsilica content at 110°C and 1500°C. The grain size distributions and shape of grains influence on Rheological behavior and flowability of castables. Due to suitable distribution of microsilica among other particle, the open porosity was reduced which resulted in high density, low porosity castable with good mechanical strength. Addition of fine particles such as microsilica into the composition decreased the interference between coarse particles. Fine particles decreased the viscosity of castable Matrix and because of that the flowability was increased. The results showed that the cement content of castable was reduced due to the small particls size of microsilica. The reduction in CaO content in low cement castables by the reduction of cement quantity reduced the formation of low temperature phases: CAS_2 and C_2ASand favored the development of Mullite phase. Also CCS and MOR were increased due to liquid phase sintering which was resulted from the increase in microsilica content. These changes were related to the resultant of microstructure and formed phases in the samples were studied and discussed.