Pseudo-equilibrium between a random system and a solution: a Monte-Carlo study of glass dissolution in water

The dissolution of a random binary glass with strongly different solubilities is studied by Monte-Carlo simulations in two dimensions. The soluble species represents Na₂O or B₂O₃. The other species, SiO₂, has a local environment-dependent solubility. For a finite volume of liquid a rapid dissolution is found until an apparent equilibrium is reached. Nevertheless, a steady state porosification continues at a lower but constant speed with restructuration of the porous surface. The simulation reproduces the restarting of dissolution at apparent equilibrium, recently observed experimentally. Dynamical percolation permits us to explain the strong dependence of the dissolution rate on the concentration.