The Dissolution Behavior in Alkaline Solutions of a Borosilicate Glass with and without P2O5
There are a variety of applications for glasses in alkaline environments, including glass fibers and glass-coated steel to reinforce concrete structures. To understand how a simple glass reacts in such environments, the dissolution behavior of a 25Na2O-25B2O3-50SiO2 (mol%) glass, doped with and without 3 mol% P2O5, in pH 12 KOH and pH 12 KOH saturated with Ca2+ ions was studied. Ca2+ ions in the solution significantly reduce the glass dissolution rate by forming a passivating calcium silicate hydrate (C-S-H) gel layer on the glass surface. When these corroded glasses were then exposed to Ca-free KOH, the C-S-H layer redissolves into the undersaturated solution and the glass dissolution rate increases. For phosphate-doped borosilicate glass, PO4 3- units released from the dissolving glass react with Ca2+ ions in saturated solutions to form crystalline hydroxylapatite on the glass surface, but this layer does not protect the glass from corrosion as well as the C-S-H does. The nature of the C-S-H layer was characterized by Raman spectroscopy, which reveals a gel layer constituted mainly of silicate anions.
X. Cheng et al., "The Dissolution Behavior in Alkaline Solutions of a Borosilicate Glass with and without P2O5," Journal of the American Ceramic Society, vol. 100, no. 10, pp. 4519-4532, Blackwell Publishing Inc., Oct 2017.
The definitive version is available at http://dx.doi.org/10.1111/jace.14933
Materials Science and Engineering
Civil, Architectural and Environmental Engineering
Keywords and Phrases
Alkalinity; Calcium Silicate; Concretes; Glass; Hydrates; HydrationIons; Silicate Minerals; Steel Fibers; Alkaline Environment; Alkaline Solutions; Chemical Durability; Dissolution Behavior; Reinforce Concrete Structure; Saturated Solutions; Borosilicate Glass
International Standard Serial Number (ISSN)
Article - Journal
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