Cold isostatic pressing of Alumina-Graphite castables, a new technology to manufacture special refractories

Abstract

The refractory materials of the special refractories like ladle shroud (LS) and submerged entry nozzle (SEN) should have adequate chemical and mechanical properties such as high temperature mechanical strength and thermal shock resistance. Currently, alumina, graphite and additives are mixed with a phenolic resin or coal tar pitch, packed into a molding frame by a jig, formed by cold isostatic pressing (CIP), dried and finally fired in a reducing atmosphere, usually under coke, at more than 1 000°C. The purpose of this research is to introduce a novel technique to provide LS and SEN from alumina-graphite castable refractories by using CIP without a need to firing under reducing atmosphere. Compositions in relation to physical-mechanical properties are investigated and mixtures like 55% alumina, 20% refractory cement, 15% graphite, 5% micro silica and 6-8 % water have shown to be promising and giving suitable results.