Aqueous processing of titanium carbide green sheets

TIC sheets were prepared by an aqueous tape-casting process. The zeta poten tial measurement showed that the isoelectric point for TiC powders in the a bsence of dispersant had a pH value of similar to3.3. According to the surf ace properties of TiC powders, a cationic polymer PEI was selected as dispe rsant. In the presence of dispersant, the isoelectric point increased to a pH value of similar to 10.4. The slip stability was determined by visual ob servation of the fluidity of the slip as well as the settling of the powder s. Results showed that the amount of dispersant required to achieve a minim um of viscosity for 50 vol% suspensions was equal to 1.2 wt%. In the absenc e and presence of dispersant, stable slips could be obtained in the pH rang es 7-9 and 11-12, respectively. The rheological measurements showed that wi th PEI as dispersant, TIC suspensions exhibited a small time dependent beha vior. With polyvinyl alcohol as binder and glycerol as plasticizer, suspens ions showed a thixotropic feature. As-cast tapes were dried in air at room temperature. The results showed that it was possible to fabricate homogeneo us green tapes with smooth surfaces rom these suspensions.