Clays, clay minerals and cordierite ceramics - a review

Abstract

The conventional methods for the synthesis of cordierite ceramics include the solid-state sintering of individual oxides of magnesium, aluminium and silicon of the corresponding chemical composition of cordierite, or sintering of the natural raw materials. Clays are used in the ceramics industries largely because of their contribution to the molding and drying properties. The most effective use of clays meets with the problems of the improvement of the working properties of clays and bodies through additions of non-plastic materials or chemicals and the influence of the clay content of ceramic bodies on their behavior during firing. Applicable nomenclatures for clays, clay minerals, ceramic raw materials, cordierite ceramics and characteristic structural properties of the cordierite and cordierite polymorphs are summarized. Selected published data confirmed the fact that identical formulation of clay mineral mixtures led to a variable mineral phases sintered in cordierite ceramics. Among the many factors, important roles play chemical and structural characteristics of individual clay minerals used in the clay mineral mixtures and methodology of processing of the green body and sintering conditions.