Studies of drying and sintering characteristics of gelcast BaTiO 3-based ceramic parts

Abstract

Drying green gelcast parts is an essential step in the gelcasting manufacturing process. In this work, the liquid desiccant method was used for drying of BaTiO 3-based semiconducting ceramic gelcast parts. The results show that the loading level of ceramic powders and the liquid desiccant concentration significantly effect the drying process and the sintering characteristics of the ceramic parts. Lowering the loading level of ceramic powders and increasing the concentration of the liquid desiccant, non-uniform and differential drying in various regions due to great solvent gradient, induces structural and residual stresses which cause defects, such as cracking, bending and other malformations, which make the articles useless during the drying process and sintering procedure. However, when the solid loading of green gelcast parts is increased to more than 45 vol.%, the stresses developed during drying can be greatly reduced, and a higher concentration of the liquid desiccant can be used without inducing defects in the drying process and defect free ceramic with a smooth surface can be obtained. Moreover, the effects of loading level of ceramic powders and thickness of parts on the density of ceramic parts were studied. Higher solid content in the gel, and lower thickness of parts, increase the density of ceramics.