Masuda Tatsuya, Asoh Hidetaka, Haraguchi Satoshi, Ono Sachiko
Graduate School of Engineering, Kogakuin University, 2665-1 Nakano, Hachioji, Tokyo 192-0015, Japan.
Toshiba Corporation Power and Industrial Systems Research and Development Center, 1 Toshiba, Fuchu, Tokyo 183-8511, Japan.
Materials (Basel). 2015 Mar 20;8(3):1350-1368. doi: 10.3390/ma8031350.
Nanoporous and single phase α-alumina membranes with pore diameters tunable over a wide range of approximately 60-350 nm were successfully fabricated by optimizing the conditions for anodizing, subsequent detachment, and heat treatment. The pore diameter increased and the cell diameter shrunk upon crystallization to α-alumina by approximately 20% and 3%, respectively, in accordance with the 23% volume shrinkage resulting from the change in density associated with the transformation from the amorphous state to α-alumina. Nevertheless, flat α-alumina membranes, each with a diameter of 25 mm and a thickness of 50 μm, were obtained without thermal deformation. The α-alumina membranes exhibited high chemical resistance in various concentrated acidic and alkaline solutions as well as when exposed to high temperature steam under pressure. The Young's modulus and hardness of the single phase α-alumina membranes formed by heat treatment at 1250 °C were notably decreased compared to the corresponding amorphous membranes, presumably because of the nodular crystallite structure of the cell walls and the substantial increase in porosity. Furthermore, when used for filtration, the α-alumina membrane exhibited a level of flux higher than that of the commercial ceramic membrane.
通过优化阳极氧化、后续分离和热处理条件，成功制备出孔径可在约60 - 350 nm的宽范围内调节的纳米多孔单相α-氧化铝膜。随着结晶形成α-氧化铝，孔径增大，胞径缩小，分别约为20%和3%，这与从非晶态转变为α-氧化铝时密度变化导致的23%体积收缩一致。然而，仍获得了直径为25 mm、厚度为50 μm的平整α-氧化铝膜，且无热变形。α-氧化铝膜在各种浓酸和浓碱溶液中以及在高压高温蒸汽环境下均表现出高耐化学性。与相应的非晶态膜相比，在1250℃热处理形成的单相α-氧化铝膜的杨氏模量和硬度显著降低，这可能是由于细胞壁的结节状微晶结构以及孔隙率的大幅增加。此外，当用于过滤时，α-氧化铝膜的通量水平高于商业陶瓷膜。
