Evaluation of the thermal resistance of selected bentonite binders

Abstract

Bentonite is one of the most widely used clays associated with various applications. In the case of foundry technology, bentonite is primarily used as a binder for the mold manufacture. The thermal resistance of bentonite binders, also called the thermal stability, is a natural property of clay minerals, depending on the source, the mineralogical and chemical composition of clay and it is also closely connected to the bentonite structure (various interlayer ions, the level of ion substitution of montmorillonite). Generally, there are various methods for evaluating this property. This contribution describes various methods of determining the bentonite thermal stability based on the evaluation of the technological parameters of bentonite molding mixtures and their comparison. These methods were chosen on the basis of a background research and practical experiences. For the experiments the bentonites commonly used in the foundries of the Czech and Slovak region were selected.