Chlorite and Chlorite Rich Talcs in cordierite

摘要

This paper presents the results of a comparative study between chlorite rich talcs (50% talc/50% chlorite) and pure chlorite ( > 95%) in the cordierite synthesis by fritting. The first part was realised in a laboratory and concerned the synthesis of pure cordierite from compositions close to the stoichiometric formula reconstituted with 3 magnesian raw materials (chlorite rich talc - chlorite -magnesite). It shows that chlorite reacts at a lower temperature and determines the properties of each formula more precisely (shrinkage - water absorption - thermal expansion). The second part was realised on a pilot scale by slip casting and concerned mullite/cordierite materials for kiln furniture with 50% calcined kaolin content. Diagrams of the reactions with pure talc and chlorite contents are proposed and show the differences obtained. With pure chlorite in comparison with chlorite rich talcs we obtain: a wider firing range, a higher firing shrinkage, a better thermal shock resistance, a better creep resistance at 1220℃.