Intrinsic properties of multi-component glass surfaces exposed to aqueous hydrofluoric (HF) and/or hydrochloric (HCl) acid-based treatments

Abstract

Acids have been used to treat glass surfaces to achieve functional advantage for years. Despite how common these types of treatments are, it is surprisingly rare to find detailed studies that examine the potentially subtle changes to glass surface properties arising from different types of chemical exposures immediately following treatment. Here, we report on the intrinsic surface properties of an alkaline-earth boroaluminosilicate glass immediately following exposure to either (1) aqueous solutions of hydrofluoric acid (HF) with varied concentrations, or (2) mixtures of HF with hydrochloric acid (HCl) in variable concentration/component ratio(s). Surface properties investigated include surface free energy, zeta potential, shallow surface composition profiles using time of flight – secondary ion mass spectroscopy and nanoscale topography via atomic force microscopy. Activation energy calculations were used to investigate the energetics of dissolution as functions of treatment chemistry, where values of approximately ∼25–35 kJ/mol were observed across most of the ranges studied. Results suggest that the properties at the topmost surface of the treated glasses are highly dependent on the type and strength of formulation used, even when the same amount of glass is dissolved. In some cases, observed trends in the data appear to be directly related to perceived shifts in the dominant reaction mechanisms between the etchant and glass that are dictated by treatment chemistry.