Control of high solid content yttria slurry with low viscosity for gelcasting

In order to fabricate ceramics using yttria powder which is an expensive rare earth compound, it is necessary to employ near net shape technique, such as gelcasting. Gelcasting, a technique which utilizes in situ polymerization of acrylamide monomers, needs high solid content slurry. However, slurry preparation is difficult because fine particles aggregate easily. This investigation was aimed at studying the effects of amount of dispersant and specific surface area on the dispersion of aqueous yttria slurries, using a rheological measurement. The viscosity measurement of 45 vol% slurry prepared from smaller specific surface area particles of yttria indicated that dispersant dosages of 1.45 mass% will give the lowest slurry viscosity. Near net-shaped parts of yttria have been successfully formed by gelcasting, using this slurry. The green bodies obtained were practically no cracks. (c) 2005 Elsevier B.V. All rights reserved.