Hydronium Ions in Soda‐lime Silicate Glass Surfaces

Abstract

The presence of leachable alkali ions, or their hydrated sites in the glass, is believed to be a determining factor for the interfacial water structure at the glass surface, influencing the surface properties of glass. The interfacial water structure on soda‐lime silicate glass in humid ambience at room temperature was analyzed with sum‐frequency‐generation (SFG) vibration spectroscopy, which can probe the interfacial water layer without spectral interferences from the gas phase water. The soda‐lime glass surface exposed to water vapor shows three sharp SFG peaks at 3200, 3430, and 3670 cm−1 in SFG, which is drastically different from the SFG spectra of the water layers on the fused quartz glass surface and the liquid water/air interface. The sharp peak at 3200 cm−1 is believed to be associated with the hydronium ions in the Na+‐leached silicate glass surface. The 3200 cm−1 peak intensity varies with the relative humidity, indicating its equilibrium with the gas phase water. It is proposed that the hydronium ions in the Na+‐leached sites produce compressive stress in the silicate glass surface; thus the growth of hydronium ions with increasing humidity might be responsible for the increased wear resistance of soda‐lime glass surfaces in near‐saturation humidity conditions.

Vapors in the ambient—A complication in tribological studies or an engineering solution of tribological problems?

“…The 3,200 cm −1 peak is strongly hydrogen-bonded OH group; the origin of this sharp feature at 3,200 cm −1 is not well understood yet, but it was tentatively assigned to the hydronium ion (or H + attached to NBO with additional water molecule) in the Na + -leached site. It was reported that the growth of this peak appeared to correlate with the increase in wear resistance of the soda lime glass surface at high humidities [110]. However, this correlation remains to be tested; it could be simply coincidental.…”

“…Surface damage was not observed between hydrophobic surfaces, suggesting that chemical reaction with water dominates the wear behavior of glass at low loads [123]. Similarly, wear is seen in soda lime glass at low contact pressures, suggesting water-induced chemical reactions between the surfaces [110].…”

“…It was speculated that the structures of water at the surface and in the subsurface region, which are determined or affected by the presence of leachable Na + ions and types of silicate network, play critical roles in the observed behavior. Somehow, this appeared to counter-act the stress corrosion effect [110].…”

Effects of humidity and counter-surface on tribochemical wear of soda-lime-silica glass

“…These reports suggest that the chemical reactivity of counter-surfaces play important roles in the mechanochemical wear of sliding interfaces. Previous investigations on environmental effects reported that the friction and wear behaviors of multicomponent silicate glass substrates tested with silica and borosilicate glass balls vary drastically with humidity [17][18][19]. In dry conditions, glass substrates were easily scratched creating a very rough and deep wear track.…”

Origin of Ultra-Low Friction of Boric Acid: Role of Vapor Adsorption

“…The PM-RAIRS spectrum represents the entire film as well as the adsorbate molecules; in contrast, SFG is known to be more surface sensitive down to sub-monolayer coverages of water molecules on surfaces exposed to ambient conditions [30,48]. Thus, SFG can reveal changes in the adsorbate layer (gas/film interface) without interference signals from the bulk film.…”