Patent ID: 8062749

Claim:
An aircraft transparency comprising a glass piece, the glass piece comprising: a chemically tempered first major surface and an opposite second major surface; a case depth, wherein the case depth is defined as a distance from the first major surface of the glass piece toward the second major surface, the distance ending at a position within the glass piece at which the glass piece has zero stress, and a tensile stress zone within the glass piece at a depth from the first major surface greater than the distance of the case depth from the first major surface, wherein glass in the tensile stress zone has 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; wherein percent by weight (“wt %”) of Al 2 O 3 +ZrO 2 is in the range 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.), and has an unabraded modulus of rupture in the range of 71 to 112 thousand pounds per square inch (“ KPSI”).