Abstract
AbstractWhile misfunctions of pH‐sensitive glass electrodes, as found in routine work at room temperature, are usually due to coatings on the glass membrane or to clogging of the reference electrode junction, the practical lifetime of glass electrodes at elevated temperatures is often limited by a critical increase of the electrical membrane resistance, by a gradual appearance of sluggish response phenomena, by deteriorations with respect to selectivity and linear response range, and/or by the generation of asymmetry potentials. Such aging behavior has been attributed to decomposition processes that occur on the glass surfaces in contact with aqueous solutions, such as selective ion exchange of alkali and alkaline earth metal ions for hydrogen ions from the solution (leaching), congruent matrix corrosion of the entire silicate network (etching), and enrichment of nearly insoluble components at the interface. This article reports on the corrosion dynamics of different electrode glasses. The theory of ion exchange and the effects of leached layers on glass surfaces are summarized. A thermodynamic approach to corrosion kinetics, originally devised for simulating the corrosion of minerals and glasses under hydrogeochemical conditions, was adopted for modeling the matrix corrosion of silicate glasses of various compositions.
Published Version
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