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Chemical Strengthening of Soda Lime Silicate Float Glass: Effect of Small Differences in the KNO 3 Bath
Author(s) -
Sglavo Vincenzo M.
Publication year - 2015
Publication title -
international journal of applied glass science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.383
H-Index - 34
eISSN - 2041-1294
pISSN - 2041-1286
DOI - 10.1111/ijag.12101
Subject(s) - soda lime , impurity , salt (chemistry) , ion exchange , materials science , float glass , lime , silicate , silicate glass , soda lime glass , sodium silicate , magnesium , sodium , mineralogy , ion , inorganic chemistry , analytical chemistry (journal) , chemical engineering , metallurgy , chemistry , environmental chemistry , composite material , organic chemistry , engineering
Six slightly different KNO 3 baths were considered in this work, for the chemical strengthening of soda lime silicate glass. Five of these were commercially available pure KNO 3 salts for industrial or laboratory use and one was a salt from an unknown source that had been already used for at least 1000 h in Na–K ion exchange. Various amounts of sodium — the main impurity — calcium, and magnesium were measured in the six salts together with other more limited contaminants. Different strengthening effects associated with clearly dissimilar ion exchange efficiency were measured on glass treated in the different melts. The presence of Na — major impurity — in the salt was revealed to be not a critical aspect, at least up to concentration of about 0.5 wt%. Instead, the “blocking” effect caused by the presence of Ca and Mg in the KNO 3 bath (also in amounts of few tens of ppm) is shown to be a major issue.