Water diffusion in Zr‐containing fiberglass materials at room temperature

Abstract

Diffusion of water into Zr‐containing silica fiberglass materials was studied at room temperature by infrared spectroscopy. Several types of experiments were performed: (a) rehydration with H2O of fiberglass materials previously calcined in air at 450°C and under vacuum at 180°C; (b) isotopic experiments for uncalcined fiberglass materials using D2O with and without the presence of sodium. Water diffusion coefficients were determined in each case. It was suggested that the transfer of the protons and water molecules occurred by different mechanisms: the protons diffused through the hydroxyl groups via the relay mechanism like in liquid water, whereas water diffused more slowly in the form of molecular water.

Hydration and reaction mechanisms on sodium silicate glass surfaces from molecular dynamics simulations with reactive force fields

“…In Section 3.3, it was briefly mentioned that one of the methods of new silanol formation is through transport of protons between NBO's. Proton transport through glasses has be observed in simulations with reactive potentials and is one of the modes of ion exchange in solids . In MD simulations all the atoms are indexed with a number that remains constant during the simulation.…”

“…Proton transport through glasses has be observed in simulations with reactive potentials 30,39,40 and is one of the modes of ion exchange in solids. 20,64,71 In MD simulations all the atoms are indexed with a number that remains constant during the simulation. A list of all oxygen atoms that are involved in the formation of a silanol (ie all oxygens that are bound to exactly 1 hydrogen within 1.2 Å and exactly 1 silicon within 2.2 Å) was made for two different time steps.…”

“…Accordingly, the process of corrosion of alkali glasses involves ion exchange and formation of gel layers and low pH values and network dissolution under basic conditions. While experimental characterization techniques focus on measuring bulk corrosion and material transport phenomena in glasses, 12,[17][18][19][20][21][22] multiscale simulation studies of hydration in glasses reveal valuable insights to drive experimental research. [23][24][25] Interactions between water and amorphous silicates always involve the dissociation of water and formation of silanols which result in the reorganization of the glass network 26,27 and the transport of glass components into the solution.…”