The Origin of Anisotropic Shrinkage in Tape-Cast Green Tapes

摘要

Cast green tapes exhibit an undesired shrinkage anisotropy attributed to particle alignment. In contrast, a high degree of particle alignment is desired for templated grain growth techniques. This paper investigates pure alumina and low temperature co-fired ceramic (LTCC) tapes, which were cast from powders of different morphology. It describes how the particle shape controls particle orientation and therefore anisotropic shrinkage. Special emphasis is given to the time dependent rotation behavior of the particles in the shear gradient during casting and to the casting parameters which influence the flow profile. This understanding is the key factor for the interpretation of particle orientation and anisotropic shrinkage.