Effect of natural and synthetic iron corrosion products on silicate glass alteration processes

In situ nuclear-glass corrosion under geological repository conditions

“…Hydrated saponite is the most stable saponite phase in the thermodynamic database but nontronite also formed, which is in agreement with previous laboratory experiments. 23 Other Mg-silicates overestimate Mg 2+ in the solution by 13% due to lower precipitation, whereas modifications of other elements remain within the uncertainties. Thus, exposure to field conditions did not cause complete dissolution of the primary Mg-bearing phase (i.e., dolomite, clays, etc.…”

“…18,19 For instance, glasscorrosion products are composed of an amorphous layer (or gel) and secondary phases, whose formation depends on environmental conditions (i.e., the temperature, pH, redox, element saturation, groundwater, glass-clay ratio, and transport parameters). 15,[20][21][22][23][24][25][26][27][28] In this study, we investigate glass corrosion in the Meuse/ Haute-Marne Underground Research Laboratory (URL) operated by Andra using a nine-year in situ experiment involving SON68 glass, 15 which is an inactive surrogate of the French R7T7 highlevel vitrified waste, and the Callovo-Oxfordian (COx) claystone rock that occurs in France as the host rock in the deep geological disposal project known as Cigéo. 29 The reactive-transport modelling of this unique in situ experiment is a step forward toward a better understanding of the processes that induce glass corrosion in geological media by corroborating the mechanisms highlighted in the laboratory with the field results.…”

A comparative review of the aqueous corrosion of glasses, crystalline ceramics, and metals

“…It is also worth noting that the associated r r appears to best represent the behavior of ancient natural and man-made glasses that have been exposed for thousands to millions of years. 11,12 Stage III has been identified in selected systems when large amounts of secondary phases such as calcium-silicate hydrates (CSH), 13 magnesium silicates, [14][15][16][17] iron silicates, [18][19][20][21] or aluminosilicate zeolites [22][23][24][25] precipitate. However, Stage III corrosion has not always been observed, with some systems exhibiting slow alteration rates representative of Stage II behavior for long periods of exposure.…”

“…For instance, the literature reports several results of a detrimental effect of iron corrosion products on glass because the formation of the passivating layer is delayed or prevented by sorption of Si onto iron compounds and more importantly by precipitation of iron silicates. 18,21,57,82,83 Precipitation of silicate minerals is an additive process: in the case of phyllosilicate precipitation, experimentally sustained by the regular supply of Fe, Mg, Ni, or Co by the aqueous environment, the alteration rate of the glass increases proportionally to the amount of secondary precipitated phases. 84 When Mg is supplied by Mg-bearing minerals, both dissolution of the primary phase and transport of reactive species can affect the composition and the thickness of the passivating layer, and thus the alteration rate.…”

Various effects of magnetite on international simple glass (ISG) dissolution: implications for the long-term durability of nuclear glasses

“…36 Iron and its associated corrosion products (primarily siderite and magnetite) have been seen to enhance glass alteration via the sorption of silica onto the surface of the iron-rich phases and the precipitation of iron silicate minerals. [37][38][39][40][41][42][43] Each of these processes shifts the equilibrium established between the glass surface layers and surrounding solution; glass alteration rates are directly dependent on the availability of iron.…”