The Effect of PVA Addition on the Microstructure of the Porous Zirconia Ceramic by Unidirectional Freeze Casting

Porous ZrO 2 ceramic was prepared by a unidirectional freeze casting using aqueous slurries containing PVA. The effects of PVA content on the microstructure of sintered bodies were investigated by a scanning electron microscopy and a mercury intrusion porosimetry. Porous ZrO 2 ceramic with continuously long-ranged pore structure was obtained by the unidirectional freeze casting of the aqueous ZrO 2 slurry, followed by sublimation of ice and firing at 1400 ℃ for 1h in air. The PVA loading of the slurry scarcely affected the pore volume of sintered bodies. However, the pore size decreased and the compressive strength increased with increasing PVA loading in the slurry. When PVA was added, branch and ladder structures occurred in pore walls. Therefore, three dimensional pore structures developed due to the increased in the connectivities of the pore walls, resulting in the decrease in pore size and the increase in compressive strength.