Pressure-molded high-alumina ceramic castables. 3. Effect of processing additives on pressure-induced compaction and properties of bauxite-quartz glass matrix systems

The effect of lignosulfonate (LST) and surface-active substances (SAS) on compaction and properties of bauxite-quartz glass matrix systems is studied. LST added at an optimum concentration to bauxite-based highly concentrated ceramic binding suspensions (HCBS) causes a 2 - 3% decrease in preform porosity. In materials sintered at high temperature the effect of decreased porosity is more pronounced. In preforms molded at 500 - 700 MPa no defect due to overpress is observed. The SAS, judged from their efficiency for decreasing porosity, are arranged in ascending order: sodium silicate water glass, sodium tripolyphosphate, complex organomineral thinner, and FS-20 castament.