Freeform injection molding of functional ceramics by hybrid additive manufacturing

Freeform Injection Molding (FIM) is a hybrid manufacturing approach where 3D-printed sacrificial polymeric molds are used for Ceramic Injection Molding (CIM). This technique offers great additive manufacturing capabilities with shape complexity and material versatility. In this paper, we present a thorough analysis of the ability of FIM to process a variety of ceramic feedstocks and evaluate samples of different geometries with increasing geometrical complexity. The materials selected are zirconia, alumina and Pb-free piezoelectrics (BaTiO₃ and (Bi, Na)TiO₃ – BaTiO₃). Injection molding simulations are used to optimize the processing parameters. The quality of the fabricated ceramic parts is assessed by the microstructure, macro-defects, the geometrical features of the structural ceramics and the piezoelectric performance of BaTiO₃ and (Bi, Na)TiO₃ – BaTiO₃. The effect of green- and sintered-density, linear shrinkage (associated with sintering), and shape distortion are also discussed.