Patent ID: 11926555
Assignee: CORNING INCORPORATED
Field: Materials, metallurgy (Chemistry)
Classification: CPC C  Y | IPC C

Claim 15:
16. A method of making a glass-ceramic article comprising:
ceramming a precursor glass article having a thickness of less than 5 mm by
a) heating the at a rate in the range from 1° C./minute to 10° C./minute to a nucleating temperature (Tn) in the range from 700° C. to 810° C.,
b) maintaining the precursor glass article at the Tn to produce a nucleated crystallizable glass article,
c) heating the nucleated precursor glass article at a rate in the range from 1° C./minute to 10° C./minute to a crystallization temperature (Tc) in the range from 850° to 1250° C.,
d) maintaining the nucleated precursor glass article at the Tc to produce a glass-ceramic article having a crystalline phase, and
e) cooling the glass-ceramic article to room temperature at an average rate in the range from 10° C./minute to 25° C./minute,

wherein the glass-ceramic article comprises a composition, in mole %, comprising:
SiO2 in the range from 62 to 75;
Al2O3 in the range from 10.5 to 17;
Li2O in the range from 5 to 13;
ZnO in the range from 0 to 4;
MgO in the range from 0 to 8;
B2O3 in the range from 0 to 4;
Na2O in the range from 0 to 5;
K2O in the range from 0 to 4;
ZrO2 in the range from 0 to 2;
P2O5 in the range from 0 to 7;
Fe2O3 in the range from 0 to 0.3;
MnOx in the range from 0 to 2;
SnO2 in the range from 0.05 mole % to 0.2 mole %;
a ratio [Li2O+Na2O+K2O+MgO+ZnO]/[Al2O3+B2O3]in the range from 0.7 to 1.5;

the crystalline phase comprises β-spodumene; and
the glass-ceramic article exhibits a Vickers crack initiation threshold of at least 12 kgf.