Ion exchange strengthened glass containing P.sub.2 O.sub.5
AssigneePPG Industries, Inc.
InventorDale W. Rinehart
Life of this patent
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Abstract
An alkali-alumina-silica-zirconia glass capable of being chemically strengthened by exchanging sodium ions in the glass with potassium ions from an external source below the strain point of the glass has its ion exchange rate increased by incorporating 2 to 20 percent P.sub.2 O.sub.5 into the initial glass composition.
Claims16
A glass essentially transparent to visible light and capable of being strengthened by ion exchange with potassium ions, comprising by weight on the oxide basis:
- 34 to 61 percent SiO.sub.2
- 12 to 20 percent Na.sub.2 O
- 2 to 9 percent K.sub.2 O
- 17 to 23 percent (Na.sub.2 O + K.sub.2 O)
- 2 to 15 percent Al.sub.2 O.sub.3
- 0to 10 percent ZrO.sub.2
- 9 to 23 percent (Al.sub.2 O.sub.3 + ZrO.sub.2)
- 2 to 20 percent P.sub.2 O.sub.5
- 0 to 8 percent ZnO
- 0 to 6 percent MgO
- 0 to 5 percent TiO.sub.2
- 2 to 9 percent (ZnO + MgO + TiO.sub.2)
- 0 to 0.1 percent Li.sub.2 O
- wherein said constituents comprise at least 90 percent by weight of the glass and are proportioned relative to one another so as to provide the glass with a viscosity of 100 poises at a temperature less than 2800.degree. F. (1538.degree. C.)
A chemically strengthened transparent glass article exhibiting a surface compressive stress after being subjected to surface abrasion composed of an interior portion which is in tension and a surface compressive layer, said interior portion comprised of by weight on the oxide basis:
- 34 to 61 percent SiO.sub.2
- 12 to 20 percent Na.sub.2 O
- 2 to 9 percent K.sub.2 O
- 17 to 23 percent (Na.sub.2 O + K.sub.2 O)
- 2 to 15 percent Al.sub.2 O.sub.3
- 0 to 10 percent ZrO.sub.2
- 9 to 23 percent (Al.sub.2 O.sub.3 + ZrO.sub.2)
- 2 to 20 percent P.sub.2 O.sub.5
- 0 to 8 percent ZnO
- 0 to 6 percent MgO
- 0 to 5 percent TiO.sub.2
- 2 to 9 percent (ZnO + MgO + TiO.sub.2)
- 0 to 0.1 percent Li.sub.2 O
- said constituents comprising at least 90 percent by weight of the interior portion and proportioned relative to one another so as to provide a glass having a viscosity of 100 poises at a temperature less than 2800.degree. F. (1538.degree. C.), said surface compressive layer having a higher content of K.sub.2 O and a lower content of Na.sub.2 O than the interior portion.
A method of strengthening a transparent glass article comprising the steps of:
- a. contacting a source of potassium ions with the surface of a glass article comprising by weight on the oxide basis:
- 34 to 61 percent SiO.sub.2
- 12 to 20 percent Na.sub.2 O
- 2 to 9 percent K.sub.2 O
- 17 to 23 percent (Na.sub.2 O + K.sub.2 O)
- 2 to 15 percent Al.sub.2 O.sub.3
- 0 to 10 percent ZrO.sub.2
- 9 to 23 percent (Al.sub.2 O.sub.3 + ZrO.sub.2)
- 2 to 20 percent P.sub.2 O.sub.5
- 0 to 8 percent ZnO
- 0 to 6 percent MgO
- 0 to 5 percent TiO.sub.2
- 2 to 9 percent (ZnO + MgO + TiO.sub.2)
- 0 to 0.1 percent Li.sub.2 O
- said constituents comprising at least 90 percent by weight of the glass article and proportioned relative to one another so as to provide a glass having a viscosity of 100 poises at a temperature less than 2800.degree. F. (1538.degree. C.);
- b. heating said source of potassium ions while in contact with the glass to a temperature at which potassium ions from said source replace sodium ions in the glass, but essentially below the strain point of the glass, thereby creating a zone of compression at the surface of the glass which extends at least 5 microns into the glass;
- and
- c. removing the glass from contact with the potassium ion source.
Dependencies are inferred from the claim text.