Low shear rate induced particle orientation in aqueous alumina green tape

Aqueous alumina slurry prepared from elongated particles with mean aspect ratio of 1.6 was chosen as the model slurry to observe low shear rate influence on particle alignment in green tape. Polarized microscope with liquid immersion technique was applied for particle orientation measurement. Orientation degree of tape cast with 1 st blade set of 0.3 mm at a constant speed of 2.5 cm/min was found in a range of 4-8%. However, the observed particle alignment was slightly different from the upper surface, which particles aligned parallel to casting direction, but on Mylar contacted surface, particles relatively inclined to the surface.