Preparation of alumina ceramics from a slurry with cellulose nanofibers

Abstract

The effect of adding cellulose nanofibers (CNFs), which are among the new materials attracting attention recently, to aqueous alumina (Al2O3) slurry was evaluated in order to investigate the possibility of using CNFs as a new forming aid. Al2O3 slurries with a small amount of CNFs (>0.1%) showed significant thixotropy. The slurry with 0.1% CNFs was cast in a gypsum mold, and Al2O3 green bodies with no cracks could be prepared after demolding and drying in air. Then Al2O3 sintered bodies with no cracks could be obtained after heating at 1600°C for 2 h. The densities of the green bodies and sintered bodies prepared from the slurry with CNFs were lower, however, than those prepared from the slurry without CNFs. In addition, the bending strength of sintered bodies prepared from the slurry with CNFs was also lower than that of those prepared from the slurry without CNFs. In order to prepare dense Al2O3 sintered bodies, it will be necessary to improve the density of the green bodies prepared from slurry with CNFs added.