US-12617714-B2 - Strengthened glass and glass strengthening method, and electronic device housing

Abstract

The present disclosure provides a strengthened glass and a glass strengthening method, and an electronic device housing. Two opposing sides of the strengthened glass have surface compressive stress layers, and a third stress layer is sandwiched between the two surface compressive stress layers. The third stress layer includes a compressive stress region and multiple tensile stress regions spaced apart within the compressive stress region, the multiple tensile stress regions are extended in a thickness direction of the strengthened glass, and each of the tensile stress regions is surrounded by the compressive stress region. A sum of thicknesses of the surface compressive stress layers and a thickness of the compressive stress region located between two adjacent tensile stress regions is equal to a thickness of the strengthened glass.

Inventors

• Yulei PEI
• Shuang Wu
• Qiying GAI
• JINGNA CUI
• Jiaxin Zhang

Assignees

• BYD COMPANY LIMITED

Dates

Publication Date

20260505

Application Date

20231228

Priority Date

20210929

Claims (20)

1. 1 . A strengthened glass, comprising: a first surface and a second surface opposite to each other, the first surface having a first surface compressive stress layer, and the second surface having a second surface compressive stress layer; and a third stress layer sandwiched between the first surface compressive stress layer and the second surface compressive stress layer, wherein the third stress layer comprises a compressive stress region and a plurality of tensile stress regions spaced apart within the compressive stress region, the plurality of tensile stress regions are extended in a thickness direction of the strengthened glass, and each of the tensile stress regions is surrounded by the compressive stress region; and a sum of a thickness of the compressive stress region, a thickness of the first surface compressive stress layer, and a thickness of the second surface compressive stress layer is equal to a thickness of the strengthened glass.
2. 2 . The strengthened glass according to claim 1 , wherein the thickness of the strengthened glass is 0.1 mm to 5 mm.
3. 3 . The strengthened glass according to claim 1 , wherein the thickness of the first surface compressive stress layer is 1% to 10% of the thickness of the strengthened glass; and the thickness of the second surface compressive stress layer is 1% to 10% of the thickness of the strengthened glass.
4. 4 . The strengthened glass according to claim 1 , wherein a surface compressive stress of the strengthened glass is greater than or equal to 500 MPa.
5. 5 . The strengthened glass according to claim 1 , wherein a quantity of the tensile stress regions in the strengthened glass is greater than or equal to 3.
6. 6 . The strengthened glass according to claim 1 , wherein a compressive stress of the compressive stress region is less than a surface compressive stress of the strengthened glass; and the compressive stress of the compressive stress region is greater than or equal to 8 MPa.
7. 7 . The strengthened glass according to claim 1 , wherein a bending strength of the strengthened glass is greater than or equal to 800 MPa.
8. 8 . The strengthened glass according to claim 1 , wherein impact resistance energy of the strengthened glass is greater than or equal to 3 J.
9. 9 . A method, comprising: forming a plurality of shielding layers that are spaced apart on a first surface and a second surface of a glass substrate, wherein the first surface and the second surface are opposite to each other, wherein the shielding layers on the first surface are in a one-to-one correspondence with the shielding layers on the second surface; performing first chemical strengthening on the glass substrate with the shielding layers, to form a first compressive stress layer on a surface of the glass substrate that is covered by the shielding layers and on a surface and an interior of the glass substrate that are not covered by the shielding layers, and form a plurality of tensile stress regions inside the glass substrate covered by the shielding layers, wherein each of the tensile stress regions is surrounded by the first compressive stress layer, and a thickness of the first compressive stress layer that is not covered by the shielding layer is equal to a thickness of the glass substrate; removing the shielding layers; and performing second chemical strengthening on the glass substrate after the shielding layers are removed to obtain a strengthened glass.
10. 10 . The method according to claim 9 , wherein a total coverage rate of the plurality of shielding layers on the first surface or the second surface is 10% to 70%.
11. 11 . The method according to claim 9 , wherein a quantity of shielding layers on the first surface or the second surface is greater than or equal to 3.
12. 12 . The method according to claim 9 , wherein when the thickness of the glass substrate is 0.5 mm or more, the first chemical strengthening is performed for 300 min or more.
13. 13 . The method according to claim 9 , wherein the first chemical strengthening is performed using a molten salt comprising a sodium element at a temperature of 350° C. to 440° C.
14. 14 . The method according to claim 9 , wherein the second chemical strengthening is performed using a molten salt comprising a potassium element at a temperature of 350° C. to 440° C.
15. 15 . The method according to claim 9 , wherein the second chemical strengthening is performed for 10 min to 200 min.
16. 16 . An electronic device housing comprising a strengthened glass, wherein the strengthened glass comprises: a first surface and a second surface opposite to each other, the first surface having a first surface compressive stress layer, and the second surface having a second surface compressive stress layer; and a third stress layer sandwiched between the first surface compressive stress layer and the second surface compressive stress layer, wherein the third stress layer comprises a compressive stress region and a plurality of tensile stress regions spaced apart within the compressive stress region, the plurality of tensile stress regions are extended in a thickness direction of the strengthened glass, and each of the tensile stress regions is surrounded by the compressive stress region; and a sum of a thickness of the compressive stress region, a thickness of the first surface compressive stress layer, and a thickness of the second surface compressive stress layer is equal to a thickness of the strengthened glass.
17. 17 . The electronic device housing according to claim 16 , wherein the thickness of the strengthened glass is 0.1 mm to 5 mm.
18. 18 . The electronic device housing according to claim 16 , wherein: the thickness of the first surface compressive stress layer is 1% to 10% of the thickness of the strengthened glass; and the thickness of the second surface compressive stress layer is 1% to 10% of the thickness of the strengthened glass.
19. 19 . The electronic device housing according to claim 16 , wherein a surface compressive stress of the strengthened glass is greater than or equal to 500 MPa.
20. 20 . The electronic device housing according to claim 16 , wherein a quantity of the tensile stress regions in the strengthened glass is greater than or equal to 3.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a Continuation Application of International Patent Application No. PCT/CN2022/120561, filed on Sep. 22, 2022, which claims priority to Chinese Patent Application No. 202111157824.6, filed on Sep. 29, 2021. The entire content of all of the above-referenced applications is incorporated herein by reference. FIELD The present disclosure relates to the field of strengthened glass technologies, and more specifically, to strengthened glass and a glass strengthening method, and an electronic device housing. BACKGROUND Glass is widely used as a cover plate in the field of electronic products. With the development of electronic products to be thinner and lighter, the mechanical performance of a glass cover plate is stricter. Chemical strengthening (that is, ion exchange) may be used to improve the mechanical performance of the glass. Large-radius ions in molten salt are used to replace small-radius ions on a surface of the glass, and a compressive stress layer with a specific thickness is formed on the surface of the glass. Although the compressive stress layer can hinder expansion of cracks in the glass, to improve a strength of the strengthened glass, a hindering effect of the compressive stress layer on expansion of microcracks is limited. Consequently, a mechanical strength of the glass is mainly affected by the microcracks on the surface and an interior of the glass. Therefore, it is necessary to provide a strengthening method that can effectively hinder the expansion of the microcracks and improve an intrinsic strength of the glass, to improve the mechanical performance of the strengthened glass. SUMMARY Based on the above, the present disclosure provides a glass strengthening method and a strengthened glass. Through a two-step chemical strengthening process, a periodic surrounding compressive stress distribution is formed inside the glass and a uniform and dense surface compressive stress layer is formed on the surface layer, so as to achieve a multi-layer hindering effect on the glass surface and internal micro-crack expansion, reduce or even eliminate the impact of a single crack on the overall strength of the glass, and improve a fracture threshold, a bending strength, an impact resistant strength, and another mechanical performance of the glass. A first aspect of the present disclosure provides a strengthened glass. The strengthened glass includes a first surface and a second surface that are disposed opposite to each other. The first surface has a first surface compressive stress layer, and the second surface has a second surface compressive stress layer. The strengthened glass further includes a third stress layer sandwiched between the first surface compressive stress layer and the second surface compressive stress layer. The third stress layer includes a compressive stress region and multiple tensile stress regions spaced apart within the compressive stress region. The multiple tensile stress regions are extended in a thickness direction of the strengthened glass, and each of the tensile stress regions is surrounded by the compressive stress region. A sum of a thickness of the compressive stress region, a thickness of the first surface compressive stress layer, and a thickness of the second surface compressive stress layer is equal to a thickness of the strengthened glass. In some embodiments, the thickness of the strengthened glass is 0.1 mm to 5 mm. In some embodiments, the thickness of the first surface compressive stress layer is 1% to 10% of the thickness of the strengthened glass; and the thickness of the second surface compressive stress layer is 1% to 10% of the thickness of the strengthened glass. In some embodiments, a surface compressive stress of the strengthened glass is greater than or equal to 500 MPa. In some embodiments, in the strengthened glass, a quantity of tensile stress regions is greater than or equal to 3. In some embodiments, a compressive stress of the compressive stress region is less than the surface compressive stress of the strengthened glass; and the compressive stress of the compressive stress region is greater than or equal to 8 MPa. In some embodiments, a bending strength of the strengthened glass is greater than or equal to 800 MPa. In some embodiments, impact resistance energy of the strengthened glass is greater than or equal to 3 J. There is a surface compressive stress layer with a relatively high stress value on the surface of the strengthened glass, and a compressive stress is distributed throughout the thickness direction of the strengthened glass between the tensile stress regions, which makes a stress depth of the strengthened glass very deep. In addition, there is a surrounding compressive stress distribution of the compressive stress region surrounding the tensile stress region inside the strengthened glass, so that expansion of cracks in the strengthened glass is further hindered, and the mechani