水热处理和尿素改性对三水铝石微观结构的影响

以尿素为改性剂,用水热处理方法对三水铝石进行了改性处理。结果表明,尿素的加入量和水热处理时间对产物微观结构有显著的影响,当尿素与三水铝石的摩尔比小于6∶1时,水热处理24 h的产物为片状薄水铝石;当摩尔比超过8∶1时,产物为板条组装的球形碱式碳酸铝铵.纯相碱式碳酸铝铵的形成与水热处理的时间有关,随处理时间的延长,氢氧化铝经历了由三水铝石到薄水铝石与碱式碳酸铝铵混相结构再到纯相碱式碳酸铝铵的演变过程,期间发生由块体到片状再到片组装块体的微观形貌变化,最后演变为板条组装球形结构。

Influence of Hydrothermal Treatment and Urea Modification on the Microstructure of Gibbsite

Gibbsite was modified by using urea as modifying agent via a hydrothermal method. Effects of the amount of urea and hydrothermal times on the microstructures were investigated. The results show that the slice-like boehmite microstructure can be obtained at 140  for 24 h when the molar ratio of urea to gibbsite is less than 6 : 1, while the global ammonium aluminum carbonate hydroxide (AACH) microstructure can be prepared at 140  for 24 h when the molar ratio was more than 8 : 1. The formation of AACH depends on the hydrothermal times. Aluminum hydroxide turned from gibbsite to the mixture of boehmite and AACH. Finally, AACH is synthesized. The morphology of aluminum hydroxide transformed from the block to the slice, and the global AACH  trchitectures assembled by the lathes were obtained finally.