Network structure in alteration layer of boroaluminosilicate glass formed by aqueous corrosion
Résumé
Exogenously-added LiCl has been shown to slightly accelerate glass corrosion rates in aqueous solutions over forward- and residual-rate regimes while KCl and CsCl impede. To understand the effect of exogenously-added electrolytes on resulting hydrous species and network structure of alteration layers, infrared spectroscopy was implemented. Results showed that the fraction of molecular water over surface-bound hydroxyl species is lower in the KCl and CsCl solutions compared to that in the LiCl and pure water ones. An approximation for the spectral features of the thin surface films from an experimentally-obtained spectrum in specular-reflectance infrared spectroscopy was proposed. Results indicated that there is no significant difference in the Si-O bonding network of the alteration layers formed in the presence of exogenously-added LiCl, KCl and CsCl. The observed change in corrosion rates might be linked to the relative abundance of molecular water in the porous glass network rather than the silicate bonding structure.