Control of pore channel size during freeze casting of porous YSZ ceramics with unidirectionally aligned channels using different freezing temperatures

详细信息    查看全文

• 作者：Liangfa Hu ; Chang-An Wang ; Yong Huang ; Chencheng Sun ; Sheng Lu ; Zijun Hu
• 关键词：Freezing casting ; Porosity ; Thermal conductivity ; Yttria-stabilized zirconia ; Insulators
• 刊名：Journal of the European Ceramic Society
• 出版年：2010
• 出版时间：December 2010
• 年：2010
• 卷：30
• 期：16
• 页码：3389-3396
• 全文大小：766 K

文摘

Porous yttria-stabilized zirconia (YSZ) ceramics with unidirectionally aligned pore channels were prepared by freezing YSZ/tert-butyl alcohol (TBA) slurry under different freezing temperatures of −30, −78 and −196 °C, respectively. After removing the frozen TBA via freeze-drying in vacuum at −50 °C, the green samples were sintered at 1450 °C for 2 h in air. The results showed that the freezing temperature significantly influenced microstructure and properties of the porous YSZ ceramics. Both microstructure observation and pore size distribution indicated that the pore channel size decreased significantly with decreasing freezing temperature, regardless of microstructure variations in the individual sample. Both porosity and room-temperature thermal conductivity of the porous YSZ ceramics varied under different freezing temperatures. Regardless of microstructure variations in the samples under different freezing temperatures, all samples had unidirectional pore channels with increasing pore channel size along the freezing direction. The fabricated samples had remarkably low thermal conductivities both in directions perpendicular and parallel to the channel direction, thus rendering them suitable for applications in thermal insulations.