- 熱測定 (ISSN:03862615)
- vol.10, no.1, pp.2-7, 1983
Thermal decomposition of magnesium sulfate heptahydrate was studied by TG-DTG-DTA under various sealed atmospheres (open, quasi-sealed, and completely sealed). In the case of open system, stable hexahydrate was obtained, and in the case of quasi-sealed system (29.8μm∅ and 130μm∅ tungsten wires), stable tri-, di-, and mono-hydrate were obtained. However in the case of completely sealed system, mono-hydrate was only obtained. Concerning the condition of completely sealed system, there is some relation between the results of MgSO<sub>4</sub>·7H<sub>2</sub>O and CaSO<sub>4</sub>·2H<sub>2</sub>O. In the case of CaSO<sub>4</sub>·2H<sub>2</sub>O, the hemihydrate was obtained under completely sealed system. The results explain directly that self-generated atmosphere plays an important role of dehydration reaction. The intermediate stages of dehydration were easily obtained by this method.