Slip-casting of coarse-grained alumina assisted by cellulose nanofibers addition

抄録

Slip-casting is a shaping technique for producing fine ceramic green bodies by mixing a raw powder with water and a dispersant to form a slurry, which is then poured into a gypsum mold to create a solid shape. Coarse-grained raw powders are less expensive but present challenges in slip-casting owing to faster sedimentation and reduced water retention, prompting the need for thickening agents to improve the process. In this study, cellulose nanofibers (CNFs) are added to a slurry to actualize the slip-casting of coarse-grained alumina (∼3.6 µm) with a sintering additive, and their effect on the castability of the slurry is investigated. The slurry without CNFs consolidates immediately after being poured into a gypsum mold. Thus, it can be concluded that slip-casting is difficult for slurries without CNFs. In contrast, the addition of CNFs to the slurry suppresses rapid water absorption and produces a healthy slip-casted green body. A suitable slurry for slip-casting is investigated by adjusting the volume fraction of alumina powder and the amount of CNFs added to the slurry. Shape forming by slip-casting becomes possible by using the optimized slurry. Moreover, a dense sintered body is produced using the slurry via slip-casting and sintering.