氟锆酸盐玻璃在中性和碱性水溶液中的耐蚀机理

Corrosion Mechanism of Fluoro-Zirconate Glasses in Neutral and Alkaline Solution

研究了氟锆酸盐玻璃在中性和碱性水溶液中的耐蚀机理,并讨论了十一种氟化物组分对玻璃耐侵蚀能力的影响。结果表明,易溶的ZrF_4在pH>7时迅速水解生成难溶的Zr(OH)_4,溶解度较小的BaF_2在pH>12时水解生成易溶的Ba(OH)_2。故氟(?)酸盐玻璃在中性和弱碱性介质中耐蚀能力最佳,强碱中次之,酸性中最差。在中性和碱性溶液中,玻璃的侵蚀为扩散控制过程,扩散层由Zr(OH)_4和其它难溶的氢氧化物构成。这一表面扩散层相当致密,保护了内层玻璃不致迅速受到侵蚀。为提高玻璃耐中性和碱性水溶液的侵蚀能力,在设计玻璃组成时,应优先选择水解速度快,其自身及水解产物溶解度小,在表面扩散层内扩散速度慢的氟化物。

Corrosion mechanism of flourozirconate glasses in neutral and alkaline solution and the effect of eleven fluoride components on chemical durability of glass were studied. The results show that corrosion of glass was a diffusion-controlled process. Diffusion layer was composed of Zr(OH)_4 and other insoluble hydroxides. The dense diffusion layer protectes the inner glass from fast corrosion. The factors affecting chemical durability of glass components are the hydrolysis tendency of each fluoride, the solubility of each fluoride and its metal hydroxide, and the mobility of soluble products in diffusion layer. The chemical durability of glass is best in solution with pH 7～12.