Chemically strengthened glass article and manufacturing method thereof
A chemically strengthened glass article in which a compressive stress value on a first surface is 400 MPa or more, a compressive stress value at a depth D B with a maximum compressive stress value in the range (0.05×t)−(0.15×t) μm is larger than the compressive stress value at a depth D A with a minimum compressive stress value in the range from the first surface to D B , a tensile stress value at a depth of (0.5×t) μm is 125 MPa or less, and a compressive stress layer depth is (0.23×t) μm or more.
1. A chemically strengthened glass article comprising a first surface, a second surface opposed to the first surface, and end portions that are in contact with the first surface and the second surface, wherein:
a compressive stress value at the first surface is 400 MPa or more;
when a compressive stress value inside the glass article is expressed with a depth from the first surface as a variable, a compressive stress value at a depth D B is larger than a compressive stress value at a depth D A ,
provided that
the compressive stress value at the depth D A is 42.9 MPa or less;
the depth D B is a depth at which a compressive stress value is maximum in a depth range, as measured from the first surface, of (0.05×t) μm to (0.15×t) μm where t (μm) is a glass thickness, and the depth D A is a depth at which a compressive stress value is minimum in a depth range from the first surface to the depth D B ;
a tensile stress value at a depth (0.5×t) μm from the first surface is 125 MPa or less; and
a compressive stress layer depth is (0.23×t) μm or more.
2. The chemically strengthened glass article according to claim 1 , wherein the compressive stress value at the depth D A is greater than 0 MPa.
3. The chemically strengthened glass article according to claim 1 , wherein the compressive stress value at the first surface is 800 MPa to 1,200 MPa.
4. The chemically strengthened glass article according to claim 1 , wherein a compressive stress value CS 80 at a depth 80 μm from the first surface, measured in MPa, is equal to or greater than (t×0.1), where t is the glass thickness measured in μm.
5. The chemically strengthened glass article according to claim 1 , wherein the glass thickness t is 200 μm to 2,000 μm.
6. The chemically strengthened glass article according to claim 1 , comprising lithium aluminosilicate glass.
7. The chemically strengthened glass article according to claim 6 , comprising a glass composition in a central portion in a thickness direction, comprising, in mass % in terms of oxides,
SiO 2 : 50% to 70%;
Al 2 O 3 : 5% to 30%;
B 2 O 3 : 0% to 10%;
P 2 O 5 : 0% to 10%;
Y 2 O 3 : 0% to 10%;
Li 2 O: 3% to 15%;
Na 2 O: 0% to 10%;
K 2 O: 0% to 10%;
(MgO+CaO+SrO+BaO): 0% to 10%; and
(ZrO 2 +TiO 2 ): 0% to 5%.
8. A method of manufacturing the chemically strengthened glass article of claim 1 , the method comprising:
immersing a glass sheet comprising lithium aluminosilicate glass in a sodium-comprising molten salt at 380° C. to 500° C. for 1 to 8 hours, wherein the sodium-comprising molten salt comprises sodium ions at 50 mass % or more with respect to a mass of metal ions in the sodium-comprising molten salt regarded as 100%; and
thereafter immersing the glass sheet in a lithium-comprising molten salt.
9. The manufacturing method according to claim 8 , wherein the lithium aluminosilicate glass comprises, in mass % in terms of oxides,
SiO 2 : 50% to 70%;
Al 2 O 3 : 5% to 30%;
B 2 O 3 : 0% to 10%;
P 2 O 5 : 0% to 10%;
Y 2 O 3 : 0% to 10%;
Li 2 O: 3% to 15%;
Na 2 O: 0% to 10%;
K 2 O: 0% to 10%;
(MgO+CaO+SrO+BaO): 0% to 10%; and
(ZrO 2 +TiO 2 ): 0% to 5%.