2024-09-19 –, K3
Calcium hexaluminate (CaAl12O19 or CA6) formation has been found to occur via solid and liquid state reactions at high temperatures in calcium and alumina containing compositions of refractory castables. In this research, focus is given to the solid-state reaction predicted for the silica-free refractory systems.
Pure alumina aggregates tend to have different morphologies (surface roughness, pore structures, grain sizes and shape) due to the varying processing routes. This affects the interaction or bonding between the matrix and the aggregates. For the formation of CA6, the diffusion of calcium into the alumina aggregates and segregation at the borders or surface at high temperatures has been reported. However, the extent of this transport mechanism due to a chemical potential gradient (Ca2+ concentration difference) is not very clear. In this paper, the influence of the type of aggregate, grain anisotropy and impurities on CA6 crystal location has been investigated and discussed. Furthermore, the expansion effects of CA6 on inducing microcracks into the aggregates and refractory castables has been analysed.
Kwasi Boateng is a doctoral candidate whose research focuses on microstructure design to enhance the thermomechanical properties of refractory castables. His work is part of the EU-funded CESAREF project, aimed at promoting the sustainable application of refractories and reducing carbon emissions in the iron and steelmaking industries. He conducts his research at the Institute of Research on Ceramics (IRCER) in collaboration with Imerys as his industrial partner.