Carbon containing castables: current status and future prospects

Abstract

Measures to overcome the main technical di fficulties hindering the development and application of carbon containing castables are discussed. The aqueous wettability and dispersion properties of graphite can be improved by coating with materials such as carbides (SiC) and oxides (Al₂O₃, TiO₂, SiO₂, MgO, ZrO₂) or by forming micropellets / briquettes. Thick and dense crack free coatings are needed not only to improve the aqueous wettability and dispersion of graphite, but also its oxidation resistance. Small and dense micropellets or briquettes enable a homogeneous distribution of graphite in the matrix to be achieved, along with acceptable mechanical strength and corrosion resistance. Coating techniques have also been used to improve the hydration resistance of aluminium based antioxidants, but detailed studies in this area are still needed. The main binder systems are currently based on superfine silica fume and hydratable alumina as these do not form low melting phases in castables. As well as developing the existing coating and micropellet/briquette fabrication techniques, future work will continue to seek novel methods of incorporating graphite, and will begin to investigate installation methods and drying and heating schedules.