Resumption of Alteration at High Temperature and pH: Rates Measurements and Comparison with Initial Rates

Resumption of alteration – corresponding to a sharp increase of glass aqueous corrosion rate – is observed under specific experimental conditions of high pH and temperature. This phenomenon may occur with long duration time, making very difficult to foresee its appearance time and rate. In this study, leach tests performed with the International Simple Glass (ISG) at high buffered pH and 90 °C show that the lower is the pH, the later is the resumption of alteration and the lower is the dissolution rate. Under the experimental conditions of this study, the resumption of alteration rate is an order of magnitude lower than the initial dissolution rate and two orders of magnitude higher than the rate of the “plateau stage” preceding the sharp increase of the corrosion rate.