Study of clay's mineralogy effect on mechanical properties of ceramic body using an experimental design

Three clays minerals namely illite (I), montmorillonite (M), and kaolin (K) were chosen as references to study the effect of mixture composition of clays on the mechanical properties and the shrinkage of the fired ceramic. The study was accomplished using the experimental design methodology. More specifically, a mixture design was carried out in order to establish relationships between mechanical strength and shrinkage of finished products and the proportions of the three clay mineral references in the mixture. The statistical study shows that the fitted models were adequate to describe these properties of fired ceramic bodies. The results demonstrate that the mechanical resistance was mainly governed by the amount of montmorillonite mineral. In fact, the mixture design performed in this study shows clearly that montmorillonite can be incorporated in industrial ceramic products up to 45 wt% with high mechanical resistance. On the other hand, the shrinkage decreases strongly with the amount of kaolin in the mixture and increases with the amount of illite while montmorillonite exhibits moderate effect on this property. The higher strength was shown in mixture in which mullite and anorthite appear together due to the presence of kaolinite and illite and give, as a consequence, a synergic power.