Glass-based articles with improved stress profiles

Abstract

Glass-based articles are provided with improved stress profiles. The glass-based articles provide improved drop performance and damage resistance. The glass-based articles may be produced with a single ion exchange treatment. Methods of manufacturing a glass-based article includes exposing a glass-based substrate to a single molten salt bath to form the glass-based article. The glass-based substrate contains lithium. The single molten salt bath includes potassium nitrate (KNO3) and potassium carbonate (K2CO3) that is dissolved in the single molten salt bath. A concentration of the K2CO3 remains at or below its solubility limit in the single molten salt bath. A concentration of lithium ions in the single molten salt bath remains at or below its solubility limit in the single molten salt bath.

What is claimed is: 
     
         1 . A method of manufacturing a glass-based article comprising:
 exposing a glass-based substrate to a single molten salt bath to form the glass-based article, wherein the glass-based substrate contains lithium, the glass-based substrate has opposing first and second surfaces defining a substrate thickness (t) and the single molten salt bath comprises:
 potassium nitrate (KNO 3 ); and 
 potassium carbonate (K 2 CO 3 ) that is dissolved in the single molten salt bath, 
   wherein a concentration of the K 2 CO 3  remains at or below its solubility limit in the single molten salt bath, and a concentration of lithium ions in the single molten salt bath remains at or below its solubility limit in the single molten salt bath.   
     
     
         2 . The method of  claim 1 , wherein the single molten salt bath comprises:
 from 0.5 wt % to 10 wt % of the Ki 2 CO 3 ; and   from 40 wt % to 99.5 wt % of the KNO 3 .   
     
     
         3 . The method of  claim 2 , wherein the single molten salt bath further comprises from 0 wt % to 60 wt % NaNO 3 . 
     
     
         4 . The method of  claim 1 , wherein the single molten salt bath further comprises:
 sodium nitrate (NaNO 3 ); and   sodium carbonate (Na 2 CO 3 ) that is dissolved in the single molten salt bath,   wherein the concentration of the Na 2 CO 3  remains at or below its solubility limit in the single molten salt bath.   
     
     
         5 . The method of  claim 1 , wherein the single molten salt bath further comprises from 0.1 wt % to 1 wt % of silicic acid. 
     
     
         6 . The method of  claim 1 , wherein the exposing occurs for from 40 minutes to 100 minutes and the single molten salt bath is maintained a temperature from about 350° C. to 430° C. during the exposing. 
     
     
         7 . The method of  claim 1 , wherein the glass-based article comprises a peak compressive stress (CS) greater than or equal to 700 MPa; a peak tension (PT) less than or equal to 61 MPa; a compressive stress at a knee (CS k ); and a depth of compression (DOC) that is greater than or equal to 0.1t. 
     
     
         8 . The method of  claim 7 , wherein the compressive stress at the knee (CS k ) is in a range from 25 MPa to 120 MPa. 
     
     
         9 . The method of  claim 7 , further comprising a spike region extending from the first surface to a depth of layer of a spike region (DOL sp ), wherein DOL sp  is greater than or equal to 4.5 micrometers, and a ratio of DOC/DOL sp  is greater than or equal to 12 and less than or equal to 23. 
     
     
         10 . The method of  claim 7 , further comprising increasing the peak compressive stress (CS) without decreasing the compressive stress at the knee (CS k ) relative to exposing the glass-based substrate to a bath comprising the KNO 3  in the absence of the K 2 CO 3 . 
     
     
         11 . The method of  claim 7 , further comprising increasing the peak compressive stress (CS) without decreasing the PT relative to exposing the glass-based substrate to a bath comprising the KNO 3  in the absence of the K 2 CO 3 . 
     
     
         12 . The method of  claim 1 , further comprising increasing a compressive stress at a knee (CS k ) without decreasing a peak compressive stress (CS) relative to exposing the glass-based substrate to a bath comprising the KNO 3  in the absence of the K 2 CO 3 . 
     
     
         13 . The method of  claim 1 , further comprising increasing a compressive stress at a knee (CS k ) without decreasing a peak compressive stress (CS) relative to exposing the glass-based substrate to a bath comprising the KNO 3  in the absence of the K 2 CO 3 . 
     
     
         14 . The method of  claim 1 , further comprising reducing a degradation of a peak compressive stress (CS) as to an increase of Li poisoning ion concentration relative to exposing the glass-based substrate to a bath comprising the KNO 3  in the absence of the K 2 CO 3 . 
     
     
         15 . The method of  claim 1 , further comprising reducing a degradation of a compressive stress at a knee (CS k ) as to an increase of Li poisoning ion concentration relative to exposing the glass-based substrate to a bath comprising the KNO 3  in the absence of the K 2 CO 3 . 
     
     
         16 . The method of  claim 1 , further comprising reducing a degradation of a peak tension (PT) as to an increase of Li poisoning ion concentration relative to exposing the glass-based substrate to a bath comprising the KNO 3  in the absence of the K 2 CO 3 . 
     
     
         17 . The method of  claim 1 , further comprising maintaining weight gain as to an increase of Li poisoning ion concentration relative to exposing the glass-based substrate to a bath comprising the KNO 3  in the absence of the K 2 CO 3 . 
     
     
         18 . The method of  claim 1 , further comprising increasing a merit index (MI) defined by CS*DOL*CS k *DOC/PT 5  relative to exposing the glass-based substrate to a bath comprising the KNO 3  in the absence of the K 2 CO 3 . 
     
     
         19 . The method of  claim 1 , wherein the glass-based substrate comprises an alkali aluminosilicate glass. 
     
     
         20 . The method of  claim 1 , wherein a molar ratio (Li 2 O/Na 2 O) of a concentration of lithium oxide (Li 2 O) at a center of the glass-based substrate to a concentration of sodium oxide (Na 2 O) at the center of the glass-based substrate is from 0.3 to 1.1.