Reaction–permeability optimum time heating policy via process control for debinding green ceramic components

Abstract

The minimisation of temperature–time schedules to thermally debind ceramic green bodies has been examined for the case when the species of binder degradation transit the green component via gas permeation in the pore space. The model is based on the spatial–temporal reaction–permeability equation in conjunction with differential equations describing the decomposition rate and temperature–time cycle, plus an algebraic constraint which limits the buildup of pressure to avoid component failure. An approach using finite elements with a process controller was compared to an approximate approach using the pseudo-steady-state modelling assumption in conjunction with the calculus of variations. The two approaches exhibit excellent agreement, which supports the accuracy of the pseudo-steady-state assumption and the usefulness of the process control strategy, both of which can save time and energy in debinding ceramic components. The process control methodology was also applied to the complex geometry of a ceramic engine valve.