Effect of Added Organics on the Preparation of Alumina Sheets by Doctor Blade Method

Abstract

The effects of added organics on the fluidity of alumina slurry for the doctor blade method and its sintered body were investigated.
The homogeneous slurry was prepared by mixing alumina powder, organics, and solvent with a ball mill. The tape casting was performed by the doctor blade method after deairing. Then, the prepared sheets were dried and fired. The viscosity of slurry, and the relative densities of green sheet and sintered body were measured.
The results obtained are summarized as follows:
(1) The viscosity of alumina slurry increased with increasing organics, and it was possible to obtain the green sheets containing 4.5 wt% to 10 wt% organics by a doctor blade method.
(2) The phenomena of shear thinning appeared clearly in the slurry with increasing aging time.
(3) The organic solution without alumina powder showed a Newtonian flow.
(4) The relative densities of green sheets were gradually increased with increasing organics, however, the packing densities of alumina were little changed.
(5) The relative densities of sintered bodies were increased with the higher sintering temperature, while little changed with the organic amount at each sintering temperature.