Impact of alkali on the passivation of silicate glass

Collin, Marie; Fournier, Maxime; Charpentier, Thibault; Moskura, Mélanie; Gin, Stéṕhane

doi:10.1038/s41529-018-0036-3

Cited by 50 publications

(65 citation statements)

References 41 publications

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“…19,43,54 Recent studies have shown that the alteration layer undergoes major reorganization owing to the high reactivity of the silicate network. [53][54][55] It results in the formation of a microporous, hydrated, amorphous material with a large majority of non-connected pores, strongly reducing water diffusion. Moreover, as the alteration layer is an evolving material undergoing pore ripening, due to incessant hydrolysis and condensation of siloxane bonds, 54 transport of aqueous species through the growing layer becomes rate-limiting.…”

Section: Discussionmentioning

confidence: 99%

Effect of thermally induced structural disorder on the chemical durability of International Simple Glass

et al. 2018

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While the influence of silicate oxide glass composition on its chemical durability is increasingly known, the contribution of structure only is less well understood, yet is crucial for an accurate description of aqueous alteration mechanisms. The effect of structural disorder can be investigated by varying the thermal history of the glass. Furthermore, the structural changes generated by selfirradiation in nuclear glasses can be compared with those induced by fast quenching. In the context of deep geological disposal of vitreous matrices, it is then challenging to address the structural impact on glass durability. Here, a borosilicate glass, the International Simple Glass, was fiberized to obtain a rapidly quenched sample. The quenching rate and fictive temperature were evaluated from in situ Raman and Brillouin spectroscopies. Multinuclear nuclear magnetic resonance was used to obtain insight into the effect of quenching on the pristine and altered glass structure. Higher bond angle distribution and lower mixing of alkalis were observed in the fast quenched glass. Some of AlO 4 groups are then Ca-compensated, while a part of BO 4 is transformed into BO 3 units. The structural modifications increase the hydrolysis of the silicate network occurring in the forward rate regime at 90°C by a factor of 1.4-1.8 depending on the pH value. Residual rate regime is similarly affected, more significantly at the beginning of the experiments conducted in silica saturated solutions. These findings prove that the reactivity of glass remains controlled by its structure under the various alteration regimes.

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Section: Discussionmentioning

confidence: 99%

Effect of thermally induced structural disorder on the chemical durability of International Simple Glass

et al. 2018

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“…7,9 Among the network formers, Si is the most abundant in typical silicate glasses and expected to be stable because the initial solution is saturated with the soluble silica species. 1,10,20,21 The Zr species is considered to be practically insoluble because the solubility product constant (K sp ) of its hydroxide is extremely small. The B species is easily dissolved.…”

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Dissolution of silica component of glass network at early stage of corrosion in initially silica‐saturated solution

et al. 2019

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Corrosion of glass in silica‐saturated solution has been performed with the assumption that dissolution of silicate species from the glass network would not occur. Using surface‐sensitive analytical techniques, we report experimental evidence suggesting the dissolution of silicate network species from a model nuclear waste glass, called international simple glass (ISG), in an aqueous solution initially saturated with soluble silica species. Results from low energy ion scattering and X‐ray photoelectron spectroscopy reveal a complete depletion of mobile element species (B, Na) from the ISG surface and an enrichment of Zr on the outmost surface. In support of spectroscopic analyses, results from topographic imaging with atomic force microscopy show a stochastic dissolution of glass surface resulting in a higher surface roughness with increasing corrosion time in aqueous solution. This study shows that a true equilibrium between soluble silica species in the solution phase and silicate species in the glass network could not be warranted by performing corrosion experiments in the solution where dissolved silica species are initially equilibrated with amorphous silica in the presence of KOH. The leaching of mobile species (B, Na) could affect the saturation level of aqueous solution and induce further dissolution of the glass surface.

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“…In either case, as the hydration front progresses and the pH in the hydrated layer increases due to the generation of free alkali, the silicate network of the glass deteriorates into a gel layer. The alteration gel layer exhibits an increased porosity resulting in cracking induced by tension between the unaltered and hydrated phases and in eventual dissolution of the glass as hydrolysis of the silica network progresses. Glass deterioration manifests visually in historical collections under two broad categories: microcracking, often called crizzling, ranging from thin, parallel lines to extended cracking, and weeping or sweating due to the presence of small liquid droplets on a glass surface or a thin, continuous surface film .…”

Section: Introductionmentioning

confidence: 99%

Application of fiber optic reflectance spectroscopy for the detection of historical glass deterioration

et al. 2019

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Historical alkali silicate glass is prone to deterioration over time due to the uptake of atmospheric water and subsequent hydrolysis of the silicate matrix. Recent studies of historical glass have provided insight into the mechanism of alteration; however, few techniques can assess early onset glass alteration noninvasively. Herein, we present fiber optic reflectance spectroscopy (FORS) as an invaluable tool to analyze historical glass alteration. We study a series of artificially aged model potash glasses and assess the nature of the alkali‐depleted alteration layer by microscopy, scanning electron microscopy (SEM) with energy dispersive spectroscopy, and FORS. We find that the model glass FORS spectra demonstrate peaks associated with hydroxide, liquid‐like water, and bound water. FORS was able to detect an alteration layer as thin as 0.66 µm. The model glass data were then used to generate a hydration thickness prediction curve in order to predict the alteration layer thickness of twenty‐one 19th‐century glass flutes of similar composition. In the one case that an actual flute sample was available, the predicted value was in good agreement with previous SEM measurement. The results indicate the ability of FORS to noninvasively assess glass deterioration and to understand the nature of absorbed water in historical glass objects.

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Impact of alkali on the passivation of silicate glass

Cited by 50 publications

References 41 publications

Effect of thermally induced structural disorder on the chemical durability of International Simple Glass

Effect of thermally induced structural disorder on the chemical durability of International Simple Glass

Dissolution of silica component of glass network at early stage of corrosion in initially silica‐saturated solution

Application of fiber optic reflectance spectroscopy for the detection of historical glass deterioration

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