塩基性炭酸マグネシウムのDTA曲線における発熱過程について Studies on the Exothermic Processes in the Thermal Decomposition of Basic Magnesium Carbonate
The exothermic reaction observed in the thermal decomposition of basic magnesium carbonate was studied by DTA and X-ray.<br>The DTA taken in air and CO<sub>2</sub> shows occasionally a very sharp exothermic peak at about 500°C in addition to the rather broad endothermic ones.<br>The relative heights of the exothermic peaks depend on the experimental conditions such as the amounts of the samples, the atmosphere (air or CO<sub>2</sub>) and the amounts or kinds of the additives (alkali or alkaline earth halides), among the examined additives magnesium chloride showed a remarkable effect.<br>From these results of the analyses the decomposition process could be explained as follows. The crystalization of MgO proceeds slowly through amorphous state corresponding to the first endothermic peak up to above the exothermic peak. At 500°C, MgCO<sub>3</sub> is formed suddenly and the amounts of MgCO<sub>3</sub> are nearly proportional to the heights of the exothermic peaks emerged at this temperature. From above this temperature, however, MgCO<sub>3</sub> decomposes immediately into MgO.<br>The mechanism of these processes under various conditions are shortly discussed.
窯業協會誌 84(970), 259-264, 1976-06-01