Anisotropic sintering behavior of freeze-cast ceramics by optical dilatometry and discrete-element simulations

Directional freeze-casting of ceramic slurries followed by freeze drying and partial sintering results in materials with highly anisotropic properties parallel and transverse to the freezing direction. Physical measurements and optical dilatometry confirm that, during sintering, freeze-cast structures experience more strain along their freezing direction than transverse to it. Discrete Element (DEM) simulations of equivalent freeze-cast structures confirm this behavior. These simulations indicate that not only is sintering anisotropic on the macroscopic scale but within the walls and macropores themselves. It was determined that the anisotropic particle contact network that resulted from the aligned macropores led to anisotropic shrinkage during sintering.