INFLUENCE OF THE SILICA GEL TECHNOLOGY ON THE HIGH TEMPERATURE MECHANICAL BEHAVIOUR OF ALUMINA CASTABLES

摘要

One of the most successful innovations in the pastdecade has been the development of cement-free binders for monolithic refractories, no-cementcastables (NCCs). The use of colloidal silica suspensions as bonding component has been widely extended at industrial scale. The major advantages of these castables are a low and fast dry-out, a maximum thermal shock resistance and highmechanical properties. Their success is close linked to development of the microstructure that defines the behavior of the material at high temperatures.However, their installation and transport are more difficult than those of cement castables due to the useof a colloidal silica suspension instead of water. In this context, the use of microsilica powder as avaluable alternative to colloidal silica has been proposed. Recent reports disclose that the flowability behavior and mechanical properties of colloidal silicagel castables and microsilica gel castables are similar. This work deals with the study of the properties ofalumina castables fabricated using both silica geltechnologies in terms of flowability, setting time, dry-out behavior and mechanical properties. The paper pays special attention to the high temperature strength and Young?s modulus, which determine their performance in the industrial processes.