Research on thermochemical reaction mechanism and model of EPDM insulator under slag deposition condition

Thermochemical ablation of insulation material caused by slag deposition in solid rocket motors has gradually attracted researchers' attention. Understanding the ablation mechanism and the ability to calculate reaction kinetics parameters determine the height of the thermal protection design for advanced solid rocket motors. In this work, the interaction of the Al2O3-C system is determined through static ablation experiments. Using XRD, HSC thermodynamic software, and a thermogravimetric analyzer, carbon thermal reduction of alumina is analyzed and the reaction mechanism and physical model are obtained. Isothermal experiments at 1,700-1,850°C and mathematical analysis obtain the kinetic parameters of overall and step-by-step reactions. Results show that the overall reaction of the Al2O3-C system consists of a three-step reaction. The overall reaction kinetics are described by the contracting area model R2 with apparent activation and frequency factors estimated as 254.5 kJ∙mol^-1 and 5.5×10⁶ min^-1, respectively.