Glass-based articles with sections of different thicknesses

Abstract

Glass-based articles having sections of different thicknesses where a maximum central tension in a thinner section is less than that of a thicker section. The articles comprise an alkali metal oxide having a independent nonzero concentrations that vary along at least a portion of the thickness of each section. Consumer electronic products may comprise the glass-based articles having sections of different thicknesses.

What is claimed is: 
     
         1 . A method of manufacturing a glass-based article comprising:
 exposing a glass-based substrate to a bath comprising alkali metal ions to ion-exchange the glass-based substrate for a period of time (t), the glass-based substrate comprising first section having a first thickness (h 1 ) and a second section having a second thickness (h 2 ), the exposing forms the glass-based article comprising:   an alkali metal oxide having a first non-zero concentration that varies in the first section from a first section surface into at least a portion of the first thickness, and the first section having a first stress profile; and   a second non-zero concentration that varies in the second section from a second section surface into at least a portion of the second thickness, and the second section having a second stress profile,   wherein the glass-based substrate comprises a diffusivity D, and 0.01561 h 1 /D<t<0.18 h 2 /D.   
     
     
         2 . The method of  claim 1 , wherein 0.07<sqrt(4Dt/h 2 )<0.85. 
     
     
         3 . The method of  claim 1 , wherein 0.18<sqrt(4Dt/h 1 )<0.67. 
     
     
         4 . The method of  claim 3 , wherein 0.25<sqrt(4Dt/h 1 )<0.51. 
     
     
         5 . The method of  claim 1 , wherein the first stress profile comprises a first central tension region comprising a first maximum central tension (CT 1 ), the second stress profile comprises a second central tension region comprising a second maximum central tension (CT 2 ), and |CT 2 | is less than |CT 1 |. 
     
     
         6 . The method of  claim 1 , wherein the first stress profile comprises a first depth of compression (DOC 1 ), the second stress profile comprises a second depth of compression (DOC 2 ), DOC 1 >0.15·h 1 , and DOC 2  is in a range from 0.075·h 2  to 0.15·h 2 . 
     
     
         7 . The method of  claim 1 , wherein the first stress profile comprises a first surface compressive stress (CS 1 ) in a first compressive stress region of 450 MPa or more, and the second stress profile comprises a second surface compressive stress (CS 2 ) in a second compressive stress region of 450 MPa or more. 
     
     
         8 . The method of  claim 1 , wherein a portion of the first stress profile extends from the first section surface to a knee, the knee is located at a depth from the first section surface in a range from about 2 micrometers to about 30 micrometers, and all points of the first stress profile located between the first section surface and the knee comprise a tangent having a value that is 10 MPa/micrometer or greater. 
     
     
         9 . The method of  claim 8 , wherein a portion of the first stress profile extends from the knee to a first depth of compression (DOC 1 ), wherein all points of the first stress profile located between the knee and DOC 1  comprise a tangent having a value from 0 MPa/micrometer to about 2 MPa/micrometer. 
     
     
         10 . The method of  claim 1 , wherein the glass-based substrate comprises a soda-lime silicate, an alkali-aluminosilicate, an alkali-containing borosilicate, an alkali-containing aluminoborosilicate, or an alkali-containing phosphosilicate. 
     
     
         11 . The method of  claim 10 , wherein the glass-based substrate is a lithium-containing aluminosilicate. 
     
     
         12 . The method of  claim 11 , wherein the alkali metal ions include potassium. 
     
     
         13 . The method of  claim 1 , wherein h 1  is in a range from 0.3 mm to 2.5 mm, and h 2  is in a range from 0.025 mm to 2.4 mm. 
     
     
         14 . The method of  claim 1 , wherein h 2  is in a range from 0.05·h 1  to 0.96·h 1 . 
     
     
         15 . The method of  claim 1 , wherein h 2  is less than h 1  by at least 100 microns. 
     
     
         16 . The method of  claim 1 , wherein the alkali metal ions comprise one or more potassium, sodium, or combinations thereof. 
     
     
         17 . The method of  claim 1 , The glass-based article of  claim 1 , wherein the alkali metal ions comprise are selected from a group consisting of: silver, copper, zinc, titanium, rubidium, cesium, and combinations thereof. 
     
     
         18 . The method of  claim 1 , wherein the alkali metal oxide is selected from a group consisting of: silver, copper, zinc, titanium, rubidium, and cesium. 
     
     
         19 . The method of  claim 1 , wherein the alkali metal oxide comprises potassium. 
     
     
         20 . The method of  claim 1 , wherein the glass-based substrate comprises:
 from 64 mol % to 68 mol % SiO 2 ;   from 12 mol % to 16 mol % Na 2 O;   from 8 mol % to 12 mol % Al 2 O 3 ;   from 0 mol % to 3 mol % B 2 O 3 ;   from 2 mol % to 5 mol % K 2 O;   from 4 mol % to 6 mol % MgO; and   from 0 mol % to 5 mol % CaO,   wherein:
 66 mol %<(SiO 2 +B 2 O 3 +CaO)≤69 mol %; 
 (Na 2 O+K 2 O+B 2 O 3 +MgO+CaO+SrO)>10 mol %; 
 5 mol %<(MgO+CaO+SrO)≤8 mol %; 
 (Na 2 O+B 2 O 3 )<Al 2 O 3 <2 mol %; 
 2 mol %<Na 2 O<Al 2 O 3 <6 mol %; and 
 4 mol %<(Na 2 O+K 2 O)<Al 2 O 3 ≤10 mol %.