High strength glass made by ion exchange

Claim 2

In a process for producing a high strength glass comprising the steps of: a. providing a glass from a composition consisting essentially, on the oxide basis by mol%, of:

Claim 3

8 to 76.6 SiO 2 , 4.4-14.9 Al 2 O 3 , 4.1 - 12.1 Na 2 O 3 , 9 - 16.1 Li 2 O, 0 - 6% ZnO and 0 - 6.9% MgO; b. contacting the glass of step (a) at a temperature of about the glass strain point or less with an alkali metal salt having a larger ionic radius alkali ion than that in said glass composition to affect ion exchange, the improvement of reducing the contacting time of step (b) to a period of about 10 - 30 minutes while at the same time improving the compressive strength of the resulting treated product without divitrification, comprising introducing into glass composition (a) from 2 - 7.8 F 2 , such that the sum of SiO 2 + Al 2 O 3 + Na 2 O + Li 2 O + ZnO + Mgo + F 2 is at least 90%, thus producing a high strength glass having a compressive surface layer of 21 - 67 microns in thickness and a bending strength between about 4,380 and 10,800 kg/cm 2 .

Claim 4

8 to 76.6 SiO 2 , 4.4-14.9 Al 2 O 3 , 4.1 - 12.1 Na 2 O 3 , 9 - 16.1 Li 2 O, 0 - 6% ZnO and 0 - 6.9% MgO; b. contacting the glass of step (a) at a temperature of about the glass strain point or less with an alkali metal salt having a larger ionic radius alkali ion than that in said glass composition to affect ion exchange, the improvement of reducing the contacting time of step (b) to a period of about 10 - 30 minutes while at the same time improving the compressive strength of the resulting treated product without divitrification, comprising introducing into glass composition (a) from 2 - 7.8 F 2 , such that the sum of SiO 2 + Al 2 O 3 + Na 2 O + Li 2 O + ZnO + Mgo + F 2 is at least 90%, thus producing a high strength glass having a compressive surface layer of 21 - 67 microns in thickness and a bending strength between about 4,380 and 10,800 kg/cm 2 .

Claim 5

Process as claimed in claim 1, wherein sodium salt is used as alkali metal salt.

Claim 6

Process as claimed in claim 1, wherein the alkali metal is a nitrate, sulfate, sulfite, bisulfite, halogen or mixture thereof.

Claim 7

Process as claimed in claim 1, wherein step (b) is conducted in a bath of potassium nitrate.

Claim 8

Process as claimed in claim 1, wherein step (b) is conducted in a bath of sodium nitrate.

Claim 9

Process as claimed in claim 1, wherein step (b) is conducted in a bath of a mixture of potassium nitrate and sodium nitrate.

Claim 10

The produce produced by the process of claim 1.