Effects of Al:Si and (Al+Na):Si ratios on the static corrosion of sodium‐boroaluminosilicate glasses

Abstract

Understanding alteration mechanisms of borosilicate glasses in aqueous media is essential to nuclear waste performance assessments to ensure radioisotopes are contained for extended durations. Aluminum is typically added to glass compositions to reduce the extent of alteration. However, previous work on 7-day durability tests has suggested that Al has a nonlinear relationship with extent of alteration. The effects of Al:Si and (Al+Na):Si substitutions on glass durability were evaluated using series of glasses based on the International Simple Glass corroded in static conditions up to 13 months in deionized water at 90°C. The alteration behavior was determined by measurement of element release in solution. The ~7-day alteration trends across the series were consistent with predicted trends. The 13-month results indicated overall alteration decreased as Al:Si ratios increased and was unaffected by changes in (Al+Na):Si except for the glass with the highest (Al+Na):Si ratio (ISG-A23N), which completely altered within 14 days. Frequent sampling and in situ Raman measurements of solutions revealed ISG-A23N experienced several distinguishable alteration rate regimes within 7 days, forming a ~100 µm alteration layer and a NaSiAlO 4 zeolite.

On the effect of Al on alumino-borosilicate glass chemical durability

“…Therefore the difference between the two groups of glasses is signi cant. It is in agreement with previous work showing that when Si is replaced by Al in ISG, glass durability in dilute conditions is highly improved up to 12 mol% of Al 2 O 3 15 . Authors believe two possible mechanisms by which Al increases the durability of glass.…”

Forty years of durability assessment of nuclear waste glass by standard methods

“…Since its advocation in Gin et al 145 , there have been over 30 studies using ISG to explore aspects of glass dissolution behaviour including, but not limited to, the effect of individual elements [148][149][150][151][152] , the influence of specific disposal environments 71,116 and the effects of glass surface properties. Several studies have investigated the dissolution of the ISG in solutions other than ultra-pure water, for example, Elia et al 117 and Mann et al 116 performed dissolution tests in KOH and young cement water to assess the effect of cement leachate on ISG dissolution.…”

Recent Advances in Corrosion Science Applicable To Disposal of High-Level Nuclear Waste

“…Diamond and circle symbols represent replicate A and B samples, respectively. Reprinted with permission from ref . Copyright 2021 The American Ceramic Society.…”