Green colored glasses
AssigneeCorning Glass Works
InventorRichard F. Reade
Life of this patent
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Abstract
The present invention is related to the production of glasses in the Li.sub.2 O--Al.sub.2 O.sub.3 --SiO.sub.2 or Na.sub.2 O--Al.sub.2 O.sub.3 --SiO.sub.2 composition systems containing NiO and TiO.sub.2. Such glasses exhibit a brown coloration when first melted but the color is converted to a green hue after exposure to a particularly-defined heat treatment. The green coloration results from the growth of a small amount of very fine-grained crystallites of nickel spinel (NiO.Al.sub.2 O.sub.3). The crystallized articles can be chemically strengthened utilizing a low temperature ion exchange reaction.
Claims11
A method for making a transparent green glass article containing crystallities in an amount of less than about 5% by volume, said crystallites consisting of nickel spinel, which consists of the steps of:
- a. melting a batch for a glass having an overall composition selected from the group:
- A. a glass consisting essentially, by weight on the oxide basis, of about 3-7.5% Li.sub.2 O, 18-28% Al.sub.2 O.sub.3, 58-72% SiO.sub.2, 0.3-4.5% NiO, 2.5-8% TiO.sub.2, and 0-3% ZrO.sub.2, the molar ratio of Al.sub.2 O.sub.3 to the sum of all modifier ions being at least 0.95;
- and
- B. a glass approximating the stoichiometry of carnegieite consisting essentially, by weight on the oxide basis, of about 10-20% Na.sub.2 O, 30-35% Al.sub.2 O.sub.3, 35-40% SiO.sub.2, 1-3% NiO, 4-8% TiO.sub.2, 0-10% K.sub.2 O, and 0-3% ZrO.sub.2, the molar ratio of Al.sub.2 O.sub.3 to the sum of all modifier ions being at least 0.95;
- b. simultaneously cooling said melt to at least below the transformation range threof and shaping a transparent glass article therefrom;
- c. heating said transparent glass article to a temperature of at least about 675.degree. C., but not more than about 900.degree. C., for a period of time sufficient to cause the growth in situ of nickel spinel crystallites;
- and then
- d. cooling said crystallized article to room temperature, said article being transparent with a green coloration.
A method for making a transparent green glass article containing crystallites in an amount of less than about 5% by volume, said crystallites consisting of nickel spinel, said article exhibiting a modulus of rupture of at least about 50,000 psi after being subjected to surface abrasion, and having an integral surface compression layer, which consists of the steps of:
- a. melting a batch for a glass having an overall composition selected from the group:
- A. a glass consisting essentially, by weight on the oxide basis, of about 3-7.5% Li.sub.2 O, 18-28% Al.sub.2 O.sub.3, 58-72% SiO.sub.2, 0.3-4.5% NiO, 2.5-8% TiO.sub.2, and 0-3% ZrO.sub.2, the molar ratio of Al.sub.2 O.sub.3 to the sum of all modifier ions being at least 0.95;
- and
- B. a glass approximating the stoichiometry of carnegieite consisting essentially, by weight on the oxide basis, of about 10-20% Na.sub.2 O, 30-35% Al.sub.2 O.sub.3, 35-40% SiO.sub.2, 1-3% NiO, 2, 4-8% TiO.sub.2 0-10% K.sub.2 O, and 0-3% ZrO.sub.2, the molar ratio of Al.sub.2 O.sub.3 to the sum of all modifier ions being at least 0.95;
- b. simultaneously cooling said melt to at least below the transformation range thereof and shaping a transparent glass article therefrom;
- c. heating said glass article to a temperature of at least about 675.degree. C., but not more than about 900.degree. C., for a period of time sufficient to cause the growth in situ of nickel spinel crystallites;
- d. subjecting said crystallized glass article, said article being transparent with a green coloration, to an ion exchange reaction selected from the group:
- I. contacting a surface of a transparent crystallized glass article made from a batch according to paragraph (A) above with an external source of Na.sup.+ and/or K.sup.+ ions at a temperature of at least 300.degree. C., but below the strain point of the glass, for a period of time sufficient to cause an exchange of Na.sup.+ and/or K.sup.+ ions on a molar basis for Li.sup.+ ions within the glass surface, this exchange causing the development of an integral surface compression layer on said transparent crystallized glass article;
- and
- Ii. contacting a surface of a transparent crystallized glass article made from a batch according to paragraph (B) above with an external source of K.sup.+ ions at a temperature of at least 300.degree. C., but below the strain point of the glass, for a period of time sufficient to cause an exchange of K.sup.+ ions on a molar basis for Na.sup.+ ions within the glass surface, this exchange causing the development of an integral surface compression layer on said transparent crystallized glass article.
Dependencies are inferred from the claim text.