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

• Applicant: Professor Dr.-Ing. Hans Roggendorf
• Subject Area: Mechanical Properties of Metallic Materials and their Microstructural Origins
• Term: from 2010 to 2013
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 163679958

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.

• DFG Programme: Research Grants