DTA of Clay Minerals

Thermal methods (DTA, TG, TMA, and dilatometry) are well-established investigative tools in clay science and related industrial applications.Clay brick manufacturers have employed these techniques to optimize their plant production procedures. 

It is also instructive to examine factors that influence the high temperature behavior of montmorillonite. Two types of aluminous mont-morillonite were identified by Grim and Kulbicki.f l They noted that the high temperature phases formed depend on the tjq)e of this mineral. 

Ceramists are particularly interested in reactions that occur in the firing range of ware, i.e., above 1200°C. It has been observed that in the range of 1200-1250°C, secondary mullite and amorphous silica are present, The silica changes to cristobalite in the range of 1240-1350°C. Primary mullite is formed below 1200°C. The kaolinite-mullite transition involves metakaolin transformation to a spinel phase and then to mullite of possible composition 3Al203 2Si02. 

The dehydration of allophanes can begin at about 100°C and continue up to about 900°C. More structural organization can also result in a rapid loss of hydroxyls in the range of 400-600°C. 

Identification of Clay Minerals Through Clay Complexes. Basic dyestuffs are adsorbed by clay minerals by a cation exchange reaction. It has been found that clay mineral-dye complexes exhibit characteristic thermograms that can be used to identify clay minerals. Certain 

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