The effect of plaster composition and binder concentration on strain mismatch and deformation of slip-cast green bodies

High-aspect ratio beams of alumina were slip cast at 30–50 vol.% solids with a level of poly(acrylic) acid corresponding to the minimum in viscosity. The beams, which were sintered in an unconstrained manner, deform into the shape of an arc at elevated temperature. The curvature of the beams was seen to increase with increasing solids loading and to depend on measures related to the particle velocity during casting. When an acrylic binder was added to the slurry, the degree of curvature was seen to increase as compared to when no binder was present. The composition of the plaster molds was seen to have a negligible effect on the magnitude of the bending. A model based upon strain mismatch indicates that a 3% variation in the green density within the beams would account for the observed amount of curvature.