Method of making high strength nepheline crystalline glass

Claim 1

A METHOD FOR MANUFACTURING A GLASS-CERAMIC BODY POSSESSING A MODULUS OF RUPTURE WHEN ABRADED OF AT LEAST ABOUT 9790 P.S.I. WHEREIN NEPHELINE CONSTITUTES THE PRINCIPAL CRYSTAL PHASE WHICH COMPRISES MELTING A BATCH FOR A GLASS COMPOSITION CONSISTING ESSENTIALLY, BY WEIGHT ON THE OXIDE BASIS, OF 48-51% SIO2, 24-27% AL2/3, 15-18% NA20, 3-6% TIO2, AND 1-3% MGO, SIMULTANEOUSLY COOLING THE MELT AT LEAST BELOW THE TRANSFORMATIN POINT OF THE MELT AND SHAPING A GLASS BODY THEREFROM, PLACING SAID GLASS BODY ON SUPPORTING MEANS, AND THEREAFTER HEATING SAID GLASS BODY AT A RATE NOT EXCEEDING ABOUT 10*C./ MINUTE TO A TEMPERATURE BETWEEN ABOUT 650*-850*C., MAINTAINING SAID GLASS BODY WITHIN SAID RANGE OF TEMPERATURES FOR AT LEAST ABOUT 1/2-HOUR, SUBSEQUENTLY HEATING SAID BODY AT A RATE NOT EXCEEDING ABOUT 10*C./MINUTE TO A TEMPERATURE BETWEEN ABOUT 900*-1050*C., MAINTAINING SAID BODY WITHIN SAID RANGE OF TEMPERATURES FOR A PERIOD OF TIME VARYING FROM AT LEAST ABOUT ONE HOUR AT THE LOWER EXTREME OF SAID RANGE TO AT LEAST ABOUT 1/2-HOUR AT THE UPPER EXTREME OF SAID RANGE TO ATTAIN THE CRYSTALLIZATION OF NEPHELINE, AND THEN COOLING SAID BODY TO ROOM TEMPERATURE.

Claim 2

A METHOD FOR MANUFACTURING A GLASS-CERAMIC BODY POSSESSING A MODULUS OF RUPTURE WHEN ABRADED OF AT LEAST ABOUT 9790 P.S.I. WHEREIN NEPHELINE CONSTITUTES THE PRINCIPAL CRYSTAL PHASE WHICH COMPRISES MELTING A BATCH FOR A GLASS COMPOSITION CONSISTING ESSENTIALLY, BY WEIGHT ON THE OXIDE BASIS, OF 48-51% SIO2, 24-27% AL2/3, 15-18% NA20, 3-6% TIO2, AND 1-3% MGO, SIMULTANEOUSLY COOLING THE MELT AT LEAST BELOW THE TRANSFORMATIN POINT OF THE MELT AND SHAPING A GLASS BODY THEREFROM, PLACING SAID GLASS BODY ON SUPPORTING MEANS, AND THEREAFTER HEATING SAID GLASS BODY AT A RATE NOT EXCEEDING ABOUT 10*C./ MINUTE TO A TEMPERATURE BETWEEN ABOUT 650*-850*C., MAINTAINING SAID GLASS BODY WITHIN SAID RANGE OF TEMPERATURES FOR AT LEAST ABOUT 1/2-HOUR, SUBSEQUENTLY HEATING SAID BODY AT A RATE NOT EXCEEDING ABOUT 10*C./MINUTE TO A TEMPERATURE BETWEEN ABOUT 900*-1050*C., MAINTAINING SAID BODY WITHIN SAID RANGE OF TEMPERATURES FOR A PERIOD OF TIME VARYING FROM AT LEAST ABOUT ONE HOUR AT THE LOWER EXTREME OF SAID RANGE TO AT LEAST ABOUT 1/2-HOUR AT THE UPPER EXTREME OF SAID RANGE TO ATTAIN THE CRYSTALLIZATION OF NEPHELINE, AND THEN COOLING SAID BODY TO ROOM TEMPERATURE.