Ultra-thin, non-frangible glass and methods of making

Abstract

Glasses having a thickness tin a range from about 0.1 mm to less than 0.4 mm which, when chemically strengthened, is non-frangible and has a physical center tension CT (also referred to herein as “physical CT”), wherein CT>|−1.956×10−16×t6+1.24274×10−12×t5−3.09196×10−9×t4+3.80391×10−6×t3−2.35207×10−3×t2+5.96241×10−1×t+36.5994|, where t is expressed in microns.

1 - 38 . (canceled) 
     
     
         39 . A method of ion exchanging a glass article having a thickness t, wherein 0.1 mm≤t<0.4 mm, the method comprising:
 a. ion exchanging the glass article in a first ion exchange bath at a temperature in a range from about 300° C. to about 500° C., the first ion exchange bath comprising from about 25% to about 100% KNO 3  by weight and up to about 75% NaNO 3  by weight; 
 b. forming a compressive stress layer, the compressive stress layer extending from a surface of the glass article to a depth of compression DOC, wherein 0.05t≤DOC≤0.22t; and 
 c. forming a tensile region in a center portion of the glass article, the tensile region extending from the depth of compression DOC to a center region of the glass article, the tensile region having a physical center tension CT, wherein CT>|−1.956×10 −16 ×t 6 +1.24274×10 −12 ×t 5 3.09196×10 −9 ×t 4 +3.80391×10 −6 t 3 −2.35207×10 −3 ×t 2 +5.96241×10 −1 ×t+36.59941, where t is expressed in microns. 
 
     
     
         40 . The method of  claim 39 , wherein forming the compressive layer comprises forming a stress profile, wherein at least a portion of the stress profile is linear and has a slope m1, and wherein 200 MPa/μm≥|m1|≥1 MPa/μm. 
     
     
         41 . The method of  claim 40 , wherein 20 MPa/μm≥|m1|≥1.2 MPa/μm. 
     
     
         42 . The method of  claim 39 , further comprising:
 a. ion exchanging the glass article in a second ion exchange bath after ion exchanging the glass article in the first ion exchange bath, the second ion exchange bath comprising; and   b. forming a second region of the stress profile, the second region extending from the surface to a first depth D1, the second region having a linear portion extending from the surface to a depth of up to about 5μm, the linear portion having a slope m2, wherein 200 MPa/μm≥|m2|≥30 MPa/μm.   
     
     
         43 . The method of  claim 42 , wherein 0.08t≤DOC≤0.22t. 
     
     
         44 . The method of  claim 42 , wherein the compressive layer has a compressive stress CS at the surface, and wherein 500 MPa≤CS≤950 MPa. 
     
     
         45 . The method of  claim 39 , wherein the glass article is non-frangible.