Pressure slip casting of coarse-grained alumina-carbon materials

Abstract

This study presents investigations on the application of pressure slip casting to produce shaped coarse-grained alumina-carbon refractories. Slurries containing alumina particle size fractions ≤3 mm, a modified coal-tar pitch, graphite, and carbon black were prepared and examined by rheological measurements and pressure filtration tests on a laboratory scale. A suitable combination of organic additives was chosen. The graphite content was found to have a significant effect on the flow behavior and the apparent porosity of the samples produced from the slurries. Scale-up experiments were performed in a modified commercial pressure casting machine. It was possible to cast dimensionally stable samples with a size of approximately 220 mm × 220 mm × 40 mm. As shown by means of computed tomography, a homogeneous distribution of the coarse grains over the whole sample was achieved. Quenching tests demonstrated the thermal shock resistance of the carbon-bonded alumina material obtained after the pyrolysis of the modified coal-tar pitch.