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Chemical Durability of Na 2 O‐K 2 O‐CaO‐SiO 2 Glasses
Author(s) -
DILMORE M. F.,
CLARK D. E.,
HENCH L. L.
Publication year - 1978
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1978.tb09355.x
Subject(s) - alkali metal , dissolution , corrosion , leaching (pedology) , scanning electron microscope , inorganic chemistry , materials science , durability , chemistry , mineralogy , analytical chemistry (journal) , metallurgy , composite material , environmental science , organic chemistry , chromatography , soil science , soil water
The mixed‐alkali effect on chemical durability was evaluated for bulk and powdered Na 2 O‐K 2 O‐CaO‐SiO 2 glasses. Two contributions to this effect are discussed, i.e. those of glass structure and corrosion solution. The magnitude of the mixed‐alkali effect depends on the pH of the corroding solution. For pH<9, alkali‐ion leaching is the major mode of glass corrosion, and the mixed‐alkali effect is large. However, for pH≥9 congruent glass dissolution is the rate‐controlling corrosion mechanism, and the effect is diminished. When ion exchange is the rate‐controlling corrosion mechanism the magnitude of the mixed‐alkali effect depends on the extent of reaction. Since the kinetics of corrosion are influenced by the ratio of glass surface area to solution volume ( SA/V ), results obtained when this ratio is large may be misleading if extrapolated to smaller ratios. Physical evidence of the mixed‐alkali effect in bulk glasses was obtained using scanning electron microscopy and ir reflection spectroscopy.