Impact of soda-lime borosilicate glass composition on water penetration and water structure at the first time of alteration

In this study, the impact of soda-lime borosilicate glass composition and particularly the effect of charge compensators such Ca and Na and, of network formers such Si and Zr, on water penetration and water structure at the first time of alteration were investigated. Two non-destructive techniques were combined: the Fourier transform infrared spectroscopy in attenuated total reflection geometry to precise the predominant alteration mechanisms and assess the water structure in altered zone and the grazing incidence X-ray reflectometry to determine the thickness of the altered glass zone allowing to calculate the water diffusion coefficients through the glasses. The results of glass alteration at pH = 3 and 30 °C have shown that hydrolysis was the predominant mechanism after few seconds for glass having a high amount of non-binding oxygen. For the other glasses, which for the diffusion was the limiting reaction, the calculated water diffusion coefficients were comprised between 10− 21 and 10− 19 m².s− 1 and vary as a function of glass composition. An activation energy of 76.9 kJ.mol− 1 was calculated and appears to be higher than inert gas diffusion through the glass highlighting that water molecules strongly interact with the glass matrix.