Non-isothermal Kinetic Analysis on the Thermal Decomposition of the Phase 517 from Hydration Product of Magnesium Sulfide Cement

In order to better understand the thermodynamic properties of magnesium oxysulfate (MOS) cement, pure reagent was analyzed to prepare magnesium sulfide cement, non-isothermal kinetics calculation of the main hydration products was also carried out, and the conversion process of magnesium sulfide cement 517 phase at different temperatures was investigated. Composition of magnesium sulfide cement prepared was measured by XRD technique, and decomposed by a comprehensive thermal analyzer, and DSC curves of magnesium sulfide cement under different temperature rising rates were processed by Kinssinger method and Dolye-Ozawa method. According to the TG-DSC curves of magnesium sulfide cement, the thermal decomposition reaction process can be divided into five stages under normal conditions. The DSC curve was processed by Kinssinger method and Dolye-Ozawa method, and the kinetic analysis was carried out to calculate the 517 phase activation energy of magnesium sulfide cement. The three stages correspond to different activation energies. Therefore, flame retardant mechanism and thermal decomposition mechanism of magnesium sulfide cement based materials are deduced.