Corning Incorporated
Ion-exchangeable glass with low coefficient of thermal expansion

Abstract:

Provided herein is a glass composition comprising: about 72 mol % to about 77 mol % SiO.sub.2; about 8 mol % to about 12 mol % Al.sub.2O.sub.3; about 10 mol % to about 14 mol % of one or more alkali oxide R.sub.2O, wherein R.sub.2O is Li.sub.2O, Na.sub.2O, K.sub.2O, Rb.sub.2O, or Cs.sub.2O; one or more divalent oxide RO, wherein RO is MgO, CaO, SrO, BaO, or ZnO; and P.sub.2O.sub.5, wherein the ratio of mol % RO/(mol % R.sub.2O+mol % RO) is at least about 0.2. The glass composition has one or more of the following characteristics: (i) a low temperature (form 25.degree. C. to 300.degree. C.) coefficient thermal expansion (LTCTE) of less than 7.5 ppm/.degree. C.; (ii) high temperature coefficient thermal expansion (HTCTE) of less than 18 ppm/.degree. C.; (iii) liquidus viscosity of at least 200,000 poise; (iv) glass temperature of at least 1100.degree. C. at 200,000 poise or at least 1200.degree. C. at 35,000 poise; and (v) a fictive temperature T.sub.f less than about 795.degree. C.