Effect of earth alkaline oxides on firing behaviour of porcelain stoneware

Abstract

Aim of this study was to investigate the relations between chemical composition and firing behaviour of porcelain stoneware formulations. The effects of magnesia and/or calcia incorporation in varying amounts into a standard stoneware formulations through combined use of calcite and magnesite on firing behaviour was studied by means of a non-contact optical dilatometer. It was shown that suitable combination of magnesite/calcite noticeably lowered peak firing temperature without narrowing the firing range. Peak firing temperatures of these bodies were also at commercially acceptable levels. Further formulations prepared with calcite, kaolin and a local clay high in iron oxide content were also shown to give acceptable chromatic co-ordinates. It was also possible to develop bodies with high whiteness values without employing zircon.