Surface nitrided alkali-free glasses cross-reference to related applications
AssigneeCorning Incorporated
InventorsAndrea Weiss Bookbinder, Dana Craig Bookbinder, Timothy Michael Gross, Pushkar Tandon
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Abstract
Alkali-free glasses are disclosed having (in weight %) 50≦SiO2≦80%, 2≦Al2O3≦17%, 8≦B2O3≦36%, and greater than or equal to 2% and less than or equal to 25% of at least one of CaO, MgO, BaO, SrO or ZnO. The alkali-free glasses can have a surface layer with greater than 0.2 weight % N. Such alkali-free glasses are achieved by nitriding processes and exhibit increased strength, scratch resistance and chemical durability.
Claims12
1-30. (canceled)
A method of strengthening an alkali-free glass composition comprising:
- subjecting a glass article comprising the alkali-free glass composition to a heated gas mixture, wherein the gas mixture comprises at least one nitrogen-containing compound, for a time and at a temperature sufficient to create in at least one surface of the glass article a nitrogen-containing layer comprising greater than 0.2 weight % N, wherein the nitrogen-containing layer increases the Young's modulus of the article.
An article comprising an alkali-free glass composition comprising a substrate comprising at least 99.9 wt % SiO2, the alkali-free glass composition comprising a surface layer comprising greater than 0.2 weight % N.
An article comprising an alkali-free glass composition comprising a molar volume greater than 26 cm3/mole, the composition comprising a surface layer comprising greater than 0.2 weight % N.
Dependencies are inferred from the claim text.