Drying of yttria stabilized zirconia cast-tapes: Effect of aging time and surfactant addition on cracking behavior

Tape-casting process was used to produce yttria stabilized zirconia (YSZ) substrates in an aqueous system using an acrylic latex binder. Concentrated suspensions were aging different times; a surfactant was added to some slips. The slips with and without surfactant were cast, and the influence of the slip aging time and surfactant addition on the drying kinetics and cracking behavior of the tapes were studied. In addition, the effect of the slip aging time and surfactant addition on the properties of the resultant green tapes were investigated. The latex particles consolidated by coalescence during the aging time of the slips and resulted in an increase in the smaller pore size of the cast-tapes. The pore radius increased with increasing the slip aging time up to 14 days thereby decreasing the capillary pressure in the liquid. Aging times over 14 days did not change the pore radius and consequently the capillary pressure. Aging before casting up to 14 days reduced cracking; however, the lower capillary pressure resulted in low green density of the cast-tapes. The addition of surfactant decreased the capillary pressure of tapes produced from slips with aging times shorter than 10 days; and resulted in tapes with lesser crack area and lower green density with respect to those without surfactant. The slip aging time at which cracking did not occur was reduced from 14 to 10 days by the surfactant.