This study compares the degradation behaviour of toughened (chemically and thermally) and not toughened glasses. Soda–lime–silica float glasses were artificially weathered in a climate chamber for up to seven days and investigated by optical microscopy, atomic force microscopy (AFM) and x-ray photoelectron spectroscopy (XPS). For all glasses, two specific carbonates were found to develop during weathering: dendritic trona (Na 3 (HCO 3 )(CO 3 ).2H 2 O) and a several nm thick layer containing sodium bicarbonate (NaHCO 3 ). Furthermore, this work shows that Mg diffusion in the surface near region of tempered and untempered glasses does occur. It is enabled by the accumulation of Na and Ca species on the glass surfaces and the accompanying changes in the glass structure in that region. While the thermal toughening of glass showed no significant effect on the degradation behaviour compared to the untoughened glass, the chemical toughening procedure leads to dramatic changes in the corrosion behaviour: lateral changes in the surface chemistry are more pronounced while vertically chemical changes do not occur as deep as in the case of tempered and untoughened glasses. This is related to the integration of K atoms in the glass network during the toughening process replacing the smaller Na species and hence reducing the interstitial spaces within the glass network and so mitigate the corrosive attack of water in the depth.
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Reiß et al. (2019) studied this question.