Patent ID: 7871703

Claim:
A chemically tempered glass piece having a case depth, defined as a distance from a surface of the glass piece that has been chemically tempered to a point within the glass piece at which there is zero stress, and a tensile stress zone, defined as interior glass within the glass piece at a depth greater than the case depth, glass in the tensile stress zone having a glass composition comprising: Ingredient Percent by weight SiO 2 60 to 75; Al 2 O 3 18 to 29; Li 2 O 3 to 9; and ZrO 2 0 to 3; where Al 2 O 3 +ZrO 2 defined as NF is 18 to 29 wt %, and wherein the glass in the tensile stress zone has at least one of the following properties: (a) a log 10 viscosity temperature of at least 1280° F. (694° C.) and (b) a liquidus temperature of at least 2350° F. (1288° C.), wherein the glass composition further comprising: Na 2 O 0 to 1.5; and/or K 2 O 0 to 0.3; and/or CaO 0 to 3; and/or MgO 0 to 3; and/or SO 3 0.02 to 0.20; and/or Total iron as Fe 2 O 3 0 to 1.25; and/or ZrO 2 0 to 3; and/or Total tin as SnO 2 0 to 0.70; and/or TiO 2 0 to 5; and/or P 2 O 5 0 to 1.75; and/or ZnO 0 to 1.25; and/or B 2 O 3 0 to 1.75; and/or where Na 2 O+K 2 O defined as R 2 O is 0 to 1.75 wt %.