Chemically tempered glass

Abstract

Chemically tempered lithium aluminosilicate glasses and methods of tempering are provided. The method allows fast tempering at moderate temperatures, which leads to a deep zone of surface tension with a high level of surface tension.

1 - 12 . (canceled) 
     
     
         13 . A chemically tempered glass article, comprising:
 a lithium aluminosilicate glass comprising SiO 2 , Al 2 O 3 , Li 2 O with 4.6 to 5.4% by weight, and Na 2 O with 8.1 to 9.7% by weight,   wherein said glass has a chemical tempered zone of compressive stress at a surface, said zone extending to a depth of at least 50 micrometers into said glass,   wherein, in said zone, lithium ions are at least partially exchanged by alkali ions, and   wherein said zone exhibits a surface tension of at least 600 MPa.   
     
     
         14 . The chemically tempered glass article of  claim 13 , wherein the glass article is a glass sheet. 
     
     
         15 . The chemically tempered glass article of  claim 13 , wherein said depth is at least 80 micrometers and said surface tension is at least 800 MPa. 
     
     
         16 . The chemically tempered glass article of  claim 13 , wherein said glass comprises:
 58 to 65% by weight of SiO 2 ;   16 to 20% by weight of Al 2 O 3 ;   0.1 to 1% by weight of B 2 O 3 ;   4.6 to 5.4% by weight of Li 2 O;   8.1 to 9.7% by weight of Na 2 O;   0.2 to 2.0% by weight of CaO; and   2.5 to 5.0% by weight of ZrO 2 .   
     
     
         17 . The chemically tempered glass article of  claim 16 , wherein said glass further comprises 0.05 to 1.0% by weight of K 2 O. 
     
     
         18 . The chemically tempered glass article of  claim 16 , wherein said glass further comprises one or more of the components selected from the group consisting of SnO 2 , CeO 2 , P 2 O 5 , and ZnO in a total proportion from 0 to 2.5% by weight. 
     
     
         19 . The chemically tempered glass article of  claim 13 , wherein said glass comprises:
 60 to 62% by weight of SiO 2 ;   17.5 to 19.5% by weight of Al 2 O 3 ;   0.5 to 0.7% by weight of B 2 O 3 ;   4.8 to 5.2% by weight of Li 2 O;   8.5 to 9.5% by weight of Na 2 O;   0.2 to 0.5% by weight of K 2 O;   0.5 to 1.2% by weight of CaO;   3.2 to 3.8% by weight of ZrO 2 ; and   one or more of the components selected from the group consisting of SnO 2 , CeO 2 , P 2 O 5 , and ZnO in a total proportion from 0.25 to 1.6% by weight.   
     
     
         20 . The chemically tempered glass article of  claim 13 , wherein said glass comprises:
 61 to 62% by weight of SiO 2 ;   17.5 to 18.5% by weight of Al 2 O 3 ;   0.5 to 0.7% by weight of B 2 O 3 ;   4.9 to 5.1% by weight of Li 2 O;   8.8 to 9.3% by weight of Na 2 O;   0.2 to 0.5% by weight of K 2 O;   0.5 to 1.2% by weight of CaO;   3.2 to 3.8% by weight of ZrO 2 ; and   one or more of the components selected from the group consisting of SnO 2 , CeO 2 , P 2 O 5 , and ZnO in a total proportion from 0.5 to 1.0% by weight.   
     
     
         21 . The chemically tempered glass article of  claim 13 , wherein the glass article is suitable for as a cover glass for a device selected from the group consisting of a mobile communication device, a digital camera, a digital photo frame, a personal digital assistant (PDA), a solar energy device, and a touch panel display. 
     
     
         22 . The chemically tempered glass article of  claim 13 , wherein the glass article is suitable for as a bullet-proof glazing for ground vehicle windows or high speed train windows. 
     
     
         23 . A method for producing a chemically tempered glass article, comprising:
 providing a glass is provided comprising SiO 2 , Al 2 O 3 , Li 2 O with 4.6 to 5.4% by weight; and Na 2 O with 8.1 to 9.7% by weight;   storing said glass in an alkali-containing salt melt for a period of not more than 8 hours to exchange alkali ions of said glass with larger alkali ions of said alkali-containing salt melt to build up a zone of compressive stress at a surface of said glass; and   ensuring said alkali-containing salt melt does not exceed a temperature of 420° C. during storing said glass,   wherein said glass builds a zone of compressive stress having a thickness of at least 50 micrometers and a surface tension of at least 600 MPa.   
     
     
         24 . The method of  claim 23 , wherein said thickness is more than 50 μm and said surface tension is more than 600 MPa. 
     
     
         25 . The method of  claim 23 , wherein said alkali-containing salt melt comprises a NaNO 3  melt. 
     
     
         26 . The method of  claim 25 , wherein said temperature is between 370° C. and 420° C. 
     
     
         27 . The method of  claim 23 , wherein the step of storing said glass in said alkali-containing salt melt comprises storing said glass in one or more melts, wherein said melt or melts comprise at least two alkali ion species with different ionic radii. 
     
     
         28 . The method of  claim 27 , wherein said one or more melts comprises a melt blend comprises salts of different alkali metals. 
     
     
         29 . The method of  claim 28 , wherein said melt blend has a content of at least 15% by weight of NaNO 3 , said surface tension is more than 800 MPa, and said thickness is deeper than 80 micrometers. 
     
     
         30 . The method of  claim 23 , wherein the step of storing said glass in said alkali-containing salt melt comprises storing said glass in a melt blend having at least two different alkali ions, wherein said melt blend includes at least 15% by weight of NaNO 3 and said temperature is less than 400° C., and wherein said surface tension is more than 800 MPa, said thickness is deeper than 80 micrometers, and said period is less than 3 hours. 
     
     
         31 . The method of  claim 23 , wherein storing said glass in said alkali-containing salt melt comprises successively storing said glass in at least two alkali salt melts having different alkali metal species, and wherein said thickness is more than 80 micrometers and said surface tension is more than 800 MPa. 
     
     
         32 . The method of  claim 23 , wherein the step of storing said glass in said alkali-containing salt melt comprises storing said glass in a first alkali salt melt before a second alkali salt melt, said first and second alkali salt melts having different compositions, said second salt melt comprising alkali ions that have a larger ionic radius than alkali ions of said first salt melt, wherein said temperature is less than 400° C., said surface tension is more than 750 MPa, said thickness is more than 80 micrometers, and said period is not more than 3 hours.