Aqueous tape casting of silicon nitride

Slurries consisting of a low cost silicon nitride powder, sintering aids yttria and alumina, dispersants, binders, defoamers and water as a solvent were optimised for tape casting by electroacoustic and viscosity measurements and by casting experiments. The slurries exhibit shear-thinning behaviour due to the highly shear-thinning binder emulsion. Crack free tapes with a maximum thickness of approx. 250 μm and a binder content of 13–15 wt.% could be obtained. The green tapes with a high flexibility and green strength could be laminated easily by compression at room temperature. After sintering a dense microstructure developed. A significant shrinkage anisotropy parallel and perpendicular to the cast direction was observed.