Research in the Field of Preparing Molded and Unmolded Refractories Based on High-Alumina HCBS. Part 2. Properties of Starting Components and Castings Based on Composite Composition HCBS. Study of the Initial Stage of Sintering and Mullitization1

Abstract

The initial stages of sintering and mullite formation are studied for specimens based on HCBS of complex composition prepared by combined wet milling of high-alumina bauxite and fuzed quartz. The starting materials have a different ratio of components and solid phase particle fineness. The initial sintering stage is in the range 900 – 950°C, and mullite formation 1100 – 1150°C. In the range 1150 – 1200°C there are simultaneously both sintering and mullite formation. Depending on fineness and fuzed quartz HCBS content the maximum amount of shrinkage is 0.35 – 0.60%. An increase in firing temperature to above 1200°C is accompanied by specimen growth and an increase in porosity. Even with an insignificant level of the proportion of sintering pores (0.09 – 0.11) materials have an ultimate strength in bending of 100 – 130 MPa and open porosity of 14 – 16%.