Anisotropic Sintering Shrinkage in Alumina Ceramics Containing Oriented Platelets

The effect of oriented α‐Al 2 O 3 platelets on densification and shrinkage behavior of tape‐cast α‐Al 2 O 3 during solid‐state sintering was studied using dilatometric sintering shrinkage experiments and microstructural characterization. Platelet‐free alumina samples exhibit isotropic shrinkage with an ∼17% linear final shrinkage. The addition of platelets retards densification, and results in anisotropic shrinkage. Initially during sintering, shrinkage is isotropic for platelet‐containing systems; however, it becomes highly anisotropic by inhibition of shrinkage in the platelet orientation direction. In the 10 vol% platelet‐containing system, shrinkage was ∼12% in the casting and the transverse directions and ∼20% in the direction perpendicular to the casting plane.