Surface modification of soda–lime–silicate glass via the high-temperature electrochemical injection of tin ions

Abstract

Under float glass process mimicking conditions, the surface modification of soda–lime–silicate glass was achieved via the electrochemical injection of tin ions. A voltage of 10 V was applied to the 7 mm thick glass at 1000 °C for 5 min between molten tin and graphite electrodes. The chemical composition, phase, and microstructure of the glass after cooling were studied using optical, scanning electron and transmission electron microscopies, X-ray diffraction, and Mössbauer spectroscopy. After applying the voltage, the glass was found to exhibit a five-layered structure with different compositions and microstructures, e.g., a glass–ceramic layer consisting of SnO2 crystalline particles dispersed in a SiO2–SnO–Al2O3 glass and a phase-separated spinodal microstructured glass layer, within ~200 μm in depth from the glass/molten tin anode. The depth dependent composition of the surface and the formation of a multilayered structure are discussed and explained in terms of the migration of ions according to the applied electric field and the chemistry of the glass. The properties that the glass is expected to have and the potential of using this method as a novel online surface modification process that can be incorporated into industrial float glass manufacturing are also discussed.