Effect of pore orientation on anisotropic shrinkage in tape-cast products

During tape casting, an anisotropic shrinkage can be observed, which is attributed to particle alignment during the casting process. The understanding of the relationship between green body microstructure and shrinkage anisotropy is of great importance for further miniaturization of multilayer ceramics. In the current study, four alumina powders with different particle shape (spherical, standard, plate-like and extreme plate-like) were used to cast green tapes. The sintering shrinkage behavior and the microstructure were analyzed. In particular, the pore orientation was determined quantitatively by using a modified linear intercept method. The relationship between pore alignment and anisotropic sintering shrinkage of cast green tapes is discussed in all three spatial directions. The shrinkage anisotropy could be correlated quantitatively with the pore anisotropy. Furthermore, this correlation was verified by mathematical modeling based on elongated particles and pores.