Dissolution behaviour of sodium silicate glasses for the production of water glasses

工业上生产水玻璃主要是通过溶解硅酸钠玻璃来生产的，这里把硅酸钠玻璃看作是玻璃腐蚀的一个极端。为了检验和造型，采用了针对普通玻璃腐蚀而开发的工艺方法，要求再延长12个月的运行时间。到目前为止所获得的结果证实了已知的硅酸盐玻璃的腐蚀机制，如离子交换，网络溶解，形成改变的表面层。尽管如此，它被证明裂纹的形成已经发生在腐蚀过程中。此外，机械磨损可以支持在转鼓中工业生产液态水玻璃期间的溶解过程。将对这一新发现的机制进行调查，如果可能的话，将其量化，并将其纳入该过程的建模。此外，一些已经获得的腐蚀样品的结果需要额外的调查。特别是水掺入玻璃或改变表面的特性应进一步检查。在这里，我们在化学研究所的一位同事的实验室中使用了共焦激光拉曼光谱仪，该仪器可以对表面进行表征，深度分辨率为几微米。这些拉曼光谱将提供更多关于所结合的水的物种形成的细节。在碱性盐水中加入其它碱，可进一步改善玻璃的腐蚀效果。这些碱性盐水可能是KOH和NH4OH，而LiOH将抑制腐蚀。通过这种方法，即使玻璃在碱性盐水中被腐蚀，也可以分析离开玻璃的钠。

In industry water glasses are mainly produced by dissolving sodium silicate glasses which is treated here as an extreme of glass glass corrosion. To characterise and modell the process methods are applied whiche were developed for the corrosion of conventional glasses.Here the prolongation of a running for additional 12 months is trequested. The results obtained so far confirm known corrosion mechanisms of silicate glasses like ion exchange, network disolution, formation of an altered surface layer. Nevertheless, it was was shown crack formation occurs already during the corrosion process. Additionally, mechanical abrasion may support the dissolution process during industrial production of liquid water glasses in a rotating drum. This newly found mechanism will be investigated, if possible quantified, and integrated into the modelling of the process. Also, some of the already obtained results on corroded samples need addition investigations. Especially the characterisation of water incorporation into glass or altered surface should be examined further. Here we have acces to confocal Laser-Raman-Spektroskopie in the laboratory of a colleague in the institute of chemistry which allows the characterisation of the surface with a depth resolution of a few micrometers. These Raman spectra shall deliever more details on the speciation of the incorporated water. A further improvement of the corrsion results will be obtained by corroding the sodium silicate glasses in alkaline brines with ather alkalis. These alkaline brines are probably KOH and NH4OH, whereas LiOH will inhibit corrosion. By this means the analysis of sodium leaving the glasses should be possible, eeven if the glasses are corroded inalkaline brines.