Monte Carlo Simulations of the Dissolution of Borosilicate Glasses in Near-Equilibrium Conditions

Journal Article · Sun Jan 01 04:00:00 EST 2012 · Journal of Non-Crystalline Solids

DOI:https://doi.org/10.1016/j.jnoncrysol.2012.03.003· OSTI ID:1037654

Kerisit, Sebastien ^[1]; Pierce, Eric M ^[2]

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1. Pacific Northwest National Laboratory (PNNL)
2. ORNL

Monte Carlo simulations were performed to investigate the mechanisms of glass dissolution as equilibrium conditions are approached in both static and flow-through conditions. The glasses studied are borosilicate glasses in the compositional range (80 x)% SiO2 (10 + x / 2)% B2O3 (10 + x / 2)% Na2O, where 5 < x < 30%. In static conditions, dissolution/condensation reactions lead to the formation, for all compositions studied, of a blocking layer composed of polymerized Si sites with principally 4 connections to nearest Si sites. This layer forms atop the altered glass layer and shows similar composition and density for all glass compositions considered. In flow-through conditions, three main dissolution regimes are observed: at high flow rates, the dissolving glass exhibits a thin alteration layer and congruent dissolution; at low flow rates, a blocking layer is formed as in static conditions but the simulations show that water can occasionally break through the blocking layer causing the corrosion process to resume; and, at intermediate flow rates, the glasses dissolve incongruently with an increasingly deepening altered layer. The simulation results suggest that, in geological disposal environments, small perturbations or slow flows could be enough to prevent the formation of a permanent blocking layer. Finally, a comparison between predictions of the linear rate law and the Monte Carlo simulation results indicates that, in flow-through conditions, the linear rate law is applicable at high flow rates and deviations from the linear rate law occur under low flow rates (e.g., at near-saturated conditions with respect to amorphous silica). This effect is associated with the complex dynamics of Si dissolution/condensation processes at the glass water interface.

• Research Organization: Oak Ridge National Laboratory (ORNL)
• Sponsoring Organization: ORNL work for others; EM USDOE - Environmental Restoration and Waste Management (EM)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1037654
• Journal Information: Journal of Non-Crystalline Solids, Journal Name: Journal of Non-Crystalline Solids Journal Issue: 10 Vol. 358; ISSN 0022-3093; ISSN JNCSBJ
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BOROSILICATE GLASS
Borosilicate glasses
CORROSION
DEPLETION LAYER
DISSOLUTION
FLOW RATE
GLASS
SILICA
SIMULATION
WATER
glass dissolution
monte carlo simulations