Infrared spectra and thermal properties of sodium silicate solutions

Abstract

An inorganic binder is a good way to mitigate the environmental issues of organic binders containing phenol, formaldehyde, etc. One of the most representative materials in the field of inorganic moulding sand binders is a group of binder systems based on alkali silicate compounds, however, many aspects need to be improved, such as flowability, usable time and moisture resistance. In order to develop and improve inorganic binders, it is necessary to understand the characteristics of raw materials and utilize them appropriately. In this study, FT-IR analysis and thermal properties of aqueous sodium silicate solution were investigated. The FT-IR analysis results indicated, that asymmetric vibrations had higher wavenumber than their symmetric vibrations and also the stretching vibrations appeared at higher energies than the deformation vibrations. FT-IR analysis of Na2SiO3 showed that the asymmetric stretching vibration absorption band of Si-O(Na) was indicated at around 1030 cm-1, and the absorption bands due to hydrated unit molecules were observed in the sodium silicate solution. As a result of TGA analysis of the dried sample, the weight loss of about 16% which was confirmed to be due to pyrolysis of the silanol group up to 500 °C, and an XRD analysis of the dried sample after heat treatment was confirmed that quartz crystals were formed at 900 °C or higher.