Zircon compatible glasses for down draw
AssigneeCorning Incorporated
InventorsMatthew John Dejneka, Adam James Ellison, Benjamin Zain Hanson
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Abstract
A glass that is down-drawable and ion exchangeable. The glass has a temperature T35kp at which the viscosity is 35 kilopoise. T35kp is less than the breakdown temperature Tbreakdown of zircon.
Claims35
A glass comprising SiO2, Al2O3, and Na2O, wherein SiO2+B2O3≧66 mol %, Al2O3≧7 mol %, B2O3≦6.27 mol %, Na2O≧9 mol %, B2O3+Na2O+K2O+MgO+CaO≧18 mol %, and CaO≦2 mol %, wherein the glass has a temperature T35kp at which the glass has a viscosity of 35 kpoise and a zircon breakdown temperature Tbreakdown at which zircon breaks down to form ZrO2 and SiO2, wherein Tbreakdown is greater than T35kp wherein Tmargin=Tbreakdown−T35kp, wherein Tmargin (° C.)=446.6−50.2[Al2O3]+22.6[B2O3]−4.4[Na2O]−3.9[K2O]−1.2[MgO+CaO] where concentrations [Al2O3], [B2O3], [Na2O], [K2O], [MgO], and [CaO] are expressed in mol %, and wherein Tmargin≧0.
A glass, the glass comprising SiO2, Al2O3, and Na2O and having a temperature T35kp at which the glass has a viscosity of 35 kpoise, wherein SiO2+B2O3≧66 mol %, Al2O3≧7 mol %, B2O3≦6.27 mol %, Na2O≧9 mol %, B2O3+Na2O+K2O+MgO+CaO≧18 mol %, and CaO≦2 mol %, and having a temperature Tbreakdown at which zircon breaks down to form ZrO2 and SiO2, wherein Tbreakdown is greater than T35kp, wherein Tmargin=Tbreakdown−T35kp, wherein Tmargin (° C.)=446.6−50.2[Al2O3]+22.6[B2O3]−4.4[Na2O]−3.9[K2O]−1.2[MgO+CaO] where concentrations [Al2O3], [B2O3], [Na2O], [K2O], [MgO], and [CaO] are expressed in mol %, and wherein Tmargin≧0.
A glass comprising SiO2, Al2O3, and Na2O, wherein SiO2+B2O3≧66 mol %, Al2O3≧7 mol %, B2O3≦6.27 mol %, Na2O≧9 mol %, B2O3+Na2O+K2O+MgO+CaO≧18 mol %, and CaO≦2 mol %, and having a breakdown margin Tmargin, wherein Tmargin (° C.)=446.6−50.2[Al2O3]+22.6[B2O3]−4.4[Na2O]−3.9[K2O]−1.2[MgO+CaO], where concentrations [Al2O3], [B2O3], [Na2O], [K2O], [MgO], and [CaO] are expressed in mol %, and wherein Tmargin≧0.
A glass comprising SiO2, Al2O3, and at least one alkali metal oxide which includes Na2O and, optionally, at least one of K2O and Rb2O, wherein SiO2+B2O3≧66 mol %, Al2O3≧7 mol %, B2O3≦6.27 mol %, Na2O≧9 mol %, B2O3+Na2O+K2O+MgO+CaO≧18 mol %, and CaO≦2 mol %, and having a breakdown margin Tmargin, wherein Tmargin=Tbreakdown−T35kp, wherein Tmargin (° C.)=446.6−50.2[Al2O3]+22.6[B2O3]−4.4[Na2O]−3.9[K2O]−1.2[MgO+CaO] where concentrations [Al2O3], [B2O3], [Na2O], [K2O], [MgO], and [CaO] are expressed in mol %, and wherein Tmargin≧0.
Dependencies are inferred from the claim text.