Fabrication of alumina green body through gelcasting process using alginate

• Published in: Materials letters 2003-05, Vol.57 (16), p.2530-2534
• Main Authors: Jia, Yu, Kanno, Yoshinori, Xie, Zhi-Peng
• Format: Article
• Language: English
• Subjects: Al 2O 3; Applied sciences; Building materials. Ceramics. Glasses; Casting; Ceramic industries; Ceramics; Chemical industry and chemicals; Exact sciences and technology; General studies; Polymer; Sodium alginate; Suspensions; Technical ceramics
• ISSN: 0167-577X; 1873-4979
• DOI: 10.1016/S0167-577X(02)01306-X

In the present work, we studied the addition of sodium alginate, a natural innoxious polymer, to coagulate alumina slurry in the fabrication of an Al 2O 3 green body. Calcium iodate was added into the alumina suspension that was dispersed in a sodium alginate solution. The slurry was stable at room temperature but it solidified with increasing temperature. A slurry of 50 vol.% alumina ceramic powder, 1 wt.% calcium iodate and 1 wt.% sodium alginate solidified after being heated at 60 °C for 1 h. In addition to this process, a chelator was used to control the gelation behavior. Associated with the effect of the chelator, the consolidation reaction rate was delayed to longer than 30 min. The gelling properties of the sodium alginate solution and the resultant alumina slurry were analyzed. The rheological behavior of the slurry was examined. Appropriate forming processes were determined. Near-net-shaped green bodies were produced. The resultant green body has uniform structure and smooth surface, and the bonding strength is as high as 8.0 MPa.