The role of thermal and transport properties on the binder burnout of injection-molded ceramic components
A mathematical model is developed for describing the decomposition and removal of binder from ceramic components formed by injection molding. The model takes into account heat transfer by conduction within the ceramic body, mass transfer by convective flow of gas products, and an Arrhenius dependence of the decomposition rate. The model is solved numerically to determine the spatial and temporal evolution of temperature, reaction rate, concentration, porosity, and pressure. The influences of the thermal and transport properties on the distribution of binder and on the buildup of pressure within the body are examined. When small temperature gradients exist across the body, the binder is removed homogenously, whereas when large temperature gradients are present, the binder is removed as a receding planar front.
In this study, two apparently similar clays have been characterised using advanced rheometry and particle-sizing techniques; the data and the blend design consequences are discussed. The analytical information has been used in the design of casting slips which have been characterised by both traditional and advanced methods. Special emphasis has been given to the interpretation of the rheological data and the particle size distributions and how these can be combined in order to optimise the casting performance of the system.