Patent ID: 8802581
Filing Date: 2014-08-12
Classification: C03B,C03C,Y10T

Abstract:
1. A glass comprising SiO 2 , Al 2 O 3 , and Na 2 O, wherein SiO 2 +B 2 O 3 ≧66 mol %, Al 2 O 3 ≧7 mol %, B 2 O 3 ≦6.27 mol %, Na 2 O≧9 mol %, B 2 O 3 +Na 2 O+K 2 O+MgO+CaO≧18 mol %, and CaO≦2 mol %, wherein the glass has a temperature T 35kp at which the glass has a viscosity of 35 kpoise and a zircon breakdown temperature T breakdown at which zircon breaks down to form ZrO 2 and SiO 2 , wherein T breakdown is greater than T 35kp wherein T margin =T breakdown −T 35kp , wherein T margin (° C.)=446.6−50.2[Al 2 O 3 ]+22.6[B 2 O 3 ]−4.4[Na 2 O]−3.9[K 2 O]−1.2[MgO+CaO] where concentrations [Al 2 O 3 ], [B 2 O 3 ], [Na 2 O], [K 2 O], [MgO], and [CaO] are expressed in mol %, and wherein T margin ≧0.