An anodic porous alumina prepared in phosphoric acid electrolyte was heat-treated under various conditions and structural transformations were investigated. Heating the anodic porous alumina resulted in crystallization from amorphous phase to transition alumina at ∼900 °C; subsequently, aluminum phosphate was formed in the anion-incorporated layer at ∼1000 °C, and finally, phase transition from transition alumina to α-alumina occurred above 1350 °C. The aluminum phosphate particles grew, and sintering of the alumina and phase transition to α-alumina was promoted with increasing temperature and total quantity of heat. When the temperature and total quantity of heat were further increased, aluminum phosphate passed into the gaseous phase and the gas migrated through straight pores to the membrane surface along with sintering of the α-alumina. By removing the aluminum phosphate particles, the introduction of mesopores inside the pore walls and expansion of the surface area can be easily achieved.

在各种条件下对在磷酸电解质中制备的阳极多孔氧化铝进行热处理，并研究其结构转变。加热阳极多孔氧化铝会导致非晶态结晶转变为约900°C的过渡氧化铝。随后，在约1000°C的阴离子结合层中形成磷酸铝，最后，在1350°C以上发生从过渡氧化铝到α-氧化铝的相变。磷酸铝颗粒生长，并且随着温度和总热量的增加，氧化铝的烧结和向α-氧化铝的相变被促进。当温度和总热量进一步增加时，磷酸铝进入气相，并且气体随着α-氧化铝的烧结通过直孔迁移至膜表面。