Dissolution of sodium silicate glasses for the production of water glass - part IV: characterisation of reaction layer and glass surface

Dathe, M.; Lebek, W.; Koslowski, E.; Bron, M.; Bräuniger, T.; Stoessel, I und Roggendorf, H. (2021): Dissolution of sodium silicate glasses for the production of water glass - part IV: characterisation of reaction layer and glass surface. In: Glass Technology-European Journal of Glass Science and Technology Part A, Bd. 62, Nr. 1: S. 9-23

Abstract

Corrosion and dissolution reactions of Na2O center dot xSiO(2) glasses (x=2.0, 2.5, and 3.3) were investigated by static and dynamic corrosion tests at pH values between 7 and 14 and temperatures of 30 and 50 degrees C. The investigated glass compositions are close to those used for water glass production. Several types of leachants with varied pH and SiO2 concentrations were applied to induce corrosion effects. One characteristic feature of the corrosion process is the development of a reaction layer on top of the corroding glasses, a process depending on leachant pH. At intermediate pH values reaction layers were observed, but not at high pH values (>12). To generate altered glass surfaces with and without reaction layers sodium silicate glasses were corroded in deionized H2O, 0.1 M NaOH, and diluted liquid sodium water glasses. The resulting samples or layer materials were investigated by scanning electron microscopy, Raman microscopy, infrared spectroscopy, or Si-29-MAS-NMR spectroscopy. Especially Raman microscopy was applied to characterize depth profiles of structural changes of silicate (Q(n)) groups and of concentration profiles of molecular H2O within reaction layers. The results are discussed with respect to influences of pH and leachant composition in order to evaluate possible corrosion mechanisms.

• Dokumententyp: Zeitschriftenartikel
• Fakultät: Chemie und Pharmazie > Department Chemie
• Themengebiete: 500 Naturwissenschaften und Mathematik > 540 Chemie
• ISSN: 1753-3546
• Sprache: Englisch