Читать книгу Encyclopedia of Glass Science, Technology, History, and Culture - Группа авторов - Страница 52

Chemical durability is a very complex property. Attempts at generating an oxide increment system for the prediction of this property are not recommended because the most basic information on chemical durability must reflect the stability of a glass in strong acids, neutral water, and strong caustic solutions. Irrespective of their role in the glass structure, even pure oxides exhibit quite a complicated stability pattern as a function of the solution pH. This is shown in Figure 11 (from [25], revised version). Clearly, a general statement like “alumina enhances the chemical durability of a glass” is erroneous. It is true, alumina enhances the chemical durability under moderately acid to fairly caustic conditions, but it destabilizes a glass exposed to strong acids. Anyway, Figure 11 provides a first guideline of the effect which may be expected from a specific oxide in a given pH range, and hence, to base a first step of development on this information. In Chapter 5.11, the approach is further elaborated.