Naβ〃－Al_2O_3与水的作用

Performances of Naβ〃-Al_2O_3 in Water

本文借助Ｘ射线衍射物相分析和热分析对Ｍｇ或Ｌｉ稳定的Ｎａβ＂－Ａｌ２Ｏ３粉体和陶瓷在不同温度条件下与水发生的作用进行了系统地研究．实验表明，在密闭的常温条件下水主要以分子形式进入Ｎａβ＂－Ａｌ２Ｏ３的传导层内，形成水合物Ｎａβ＂－Ａｌ２Ｏ３·Ｈ２Ｏ；随着温度的升高，在β＂－Ａｌ２Ｏ３中将发生Ｈ３Ｏ＋与Ｎａ＋之间的离子交换，生成（Ｎａ＋，Ｈ３Ｏ＋）β＂－Ａｌ２Ｏ３·Ｈ２Ｏ；当温度进一步提高至２５０℃时，β＂－Ａｌ２Ｏ３结构明显地分解，产生一系列氢氧化物，通常离子交换和分解速度较慢，在短时间内仅局限于陶瓷的表面．研究认为，水合化的β＂－Ａｌ２Ｏ３对泥浆中的游离Ｎａ＋离子具有束缚作用．

The performances of Naβ〃-Al2O3(Mg) and Naβ〃-Al2O3(Li) ceramilcs and powders in water were investigated systematically by X-ray diffraction and thermal analysis. The experiments show that H2O molecules could eliter the conduction planes at room temperature to form the hydrated compound Naβ〃Al2O3.H2O. When the temperature is raised, the ion exchange between Na+ in β〃-Al2O3 takes place, leading to the formation of mired-ion Na+-H3O+β〃-Al2O3.H,O. While at temperatures over 250℃,Na+β〃Al2O3.H2O is decomposed markedly and converts to several hydrokides. The rate of ion exchange and decomposition are usually low and therefore are restricted over ceramic surfaCe. The experimental results suggest that hydrated Naβ〃-Al2O3.H2O grains are able to bind free sodium ions in the slumes resulted.