The Density, Compressive Strength And High Temperature Stability Of Al₂O₃-based Ledge Composite For Aluminum Electrolysis Cells

The regular ledge is the foundation of aluminum electrolysis cells operation with high efficiency, low consumption and stability. However, the profile of self-formation ledge in traditional cells is so hard to control that energy consumption and stability of cells increase and decrease respectively. The man-made ledge cells is a new structure aluminum electrolysis cells with high efficiency, low consumption, the cell’s ledge was built along shell to form ideal profile and don’t need to experience the adjustment period. Based on this background, with the aim of developing satisfactory man-made ledge material, and with the preparation method of pressureless liquid sintering, Al2O3/Na3AlF6composite, particle gradation Al2O3/Na3AlF6composite and Al203/MgAl204composite have been investigated. The main achievements are as follows:1) With the increase of Na3AlF6content, the relative density and compressive strength of Al2O3/Na3AlF6composite increased and the high-temperature stability gradually became poor. The high-temperature stability of composite was better than self-formed ledge material. The relative density and compressive strength of the composite first increased and then decreased when sintering temperature increases. The effect of sintering temperature on high-temperature stability of the composite was insignificant.2) The relative density of particle gradation Al2O3/Na3AlF6composite decreased and the compressive strength increased slightly with the increasing of Na3AlF6content. Although the skeleton structure of the composite could improve the high-temperature stability effectively, the high-temperature stability gradually became poor with the increase of Na3A1F6content. The increasing of powder content not only lowered the relative density but also made high-temperature stability be worse. The compressive strength first increased and then decreased when powder content increases. 3) The microstructure of Al2O3/MgAl2O4composite would be changed notably and compressive strength increased obviously when MgO content increases. Although the relative density of the composite could not improve, the high-temperature stability of the composite gradually became good with the increase of MgO content. The effect of sintering temperature on spinelisation degree of the composite was insignificant at1000℃～1200℃. The relative density of the composite first increased and then decreased, the compressive strength increased and the high-temperature stability would be slightly improved when sintering temperature increases.