Thermal Debinding Kinetics of Gelcast Ceramic Parts via a Modified Independent Parallel Reaction Model in Comparison with the Multiple Normally Distributed Activation Energy Model.

This work aims to provide useful insights into the thermal debinding kinetics of gelcast ceramic parts, especially for debinding kinetics prediction involving heat preservation. Debinding experiments were conducted in a differential thermogravimetric analyzer at five heating rates (5, 8, 10, 15, and 20 °C/min) in the temperature range of 35-900 °C under an air atmosphere. The conversion (α) and pyrolysis rate (dα/d) data were simulated using a modified independent parallel reaction (IPR) model and a multiple normally distributed activation energy model (M-DAEM). Their validity was assessed and compared by checking the agreement between the experimental results and the prediction capability. The results showed that both the modified IPR model and M-DAEM had high predictability for thermal debinding kinetics under linear heating conditions. The fitting quality parameters (Fit) were less than 1.406 and 1.01%, respectively. The activation energies ( , = 1, 2, 3, 4, and 5) calculated by the M-DAEM ranged from 153.312 to 217.171 kJ/mol. The relationships between of pseudo components 1 to 5 calculated by the modified IPR model were a function of the conversion rate. The values were (α) = 116.750 + 11.153α - 26.772α + 4.362α kJ/mol, (α) = 139.595 - 66.162α + 75.702α - 38.041α kJ/mol, (α) = 190.854 + 135.755α - 214.801α + 116.093α kJ/mol, (α) = 64.068 + 280.086α - 380.270α + 264.724α kJ/mol, and (α) = 188.257 - 77.086α + 74.129α - 48.669α kJ/mol, respectively. However, it is noteworthy that the α and dα/d curves predicted by the modified IPR model with a deviation of less than 8% were better than those predicted by the M-DAEM for the linear thermal debinding process with the holding stage. Accordingly, it is believed that the proposed modified IPR model is suitable for describing the thermal debinding kinetics involving the heat preservation of gelcast green parts.