Chemical durability of oxide glasses in aqueous solutions: A review

According to common perception, glass has a chemical durability superior to most other materials. Nevertheless, when a piece of glass is exposed to an aqueous solution, corrosion takes place. In the first part of the paper, the different equilibrium-like states related to glass dissolution are discussed. This refers to the bulk glass itself, to the aqueous solution loaded with corrosion products, to the solubility of water in glass, and to the glass surface exposed to an aqueous solution. Special attention is paid to the nature of the subsurface zone formed upon corrosion. Finally, the validity of so-called linear free energy relationships between corrosion rates and the Gibbs energy differences of products and educts is addressed. In the second part, the mechanisms controlling the corrosion rates are discussed. Surface reaction control mechanisms leading to affinity-based rate laws are presented, and contrasted to pore diffusion mechanisms probably explaining more accurately the slowdown of reaction rates in static corrosion scenarios.