Development of Packing Structure of Powder Particles in Tape Casting

Abstract

Particle packing structure in alumina green tape was studied by optical microscopy with a special focus on the direction of alignment and the degree of orientation. The effect of processing conditions on the packing structure was also examined. Non-uniformity of the c-axes orientation of alumina particles and variation of its orientation degree existed in the tape thickness direction (z-axis). The tape cast with a narrow blade exit length and low casting speed showed a relatively large non-uniform structure. The c-axes of alumina particles aligned more strongly along the z-axis at the upper surface than the lower surface, where the orientation deviated from the z-axis. A moderate local c-axes orientation at the lower surface was developed after the increases of either the blade exit length or the casting speed, however, the orientation degree varied from the upper to the lower surfaces.