阅读说明：本技术 玻璃及其制备方法、壳体组件和电子设备 (Glass, preparation method thereof, shell assembly and electronic equipment ) 是由 王小伟 于 2019-10-15 设计创作，主要内容包括：本申请提供了玻璃及其制备方法、壳体组件和电子设备,该玻璃的外表面具有压应力层,所述玻璃的外表面具有压应力层,所述压应力层的表面压应力为900～1500MPa。相对于相关技术中的强化玻璃,该玻璃的表面压应力得到明显提升,对玻璃的弯曲破裂、钝物冲击破裂(如钢球冲击)等性能得到有效改善。(The application provides glass, a preparation method of the glass, a shell assembly and electronic equipment, wherein the outer surface of the glass is provided with a pressure stress layer, the outer surface of the glass is provided with the pressure stress layer, and the surface pressure stress of the pressure stress layer is 900-1500 MPa. Compared with the tempered glass in the related technology, the surface compressive stress of the glass is obviously improved, and the performance of bending fracture, blunt object impact fracture (such as steel ball impact) and the like of the glass is effectively improved.)

1. The glass is characterized in that the outer surface of the glass is provided with a compressive stress layer, and the surface compressive stress of the compressive stress layer is 900-1500 MPa.

2. The glass of claim 1, wherein the glass has a depth of compressive stress layer in a range from 10% to 25% of the thickness of the glass.

3. The glass according to claim 1, wherein the compressive stress layer comprises a first compressive stress layer, a second compressive stress layer and a third compressive stress layer which are sequentially arranged from inside to outside, metal ions are contained in the compressive stress layer, the metal ions comprise small-radius metal ions and medium-radius metal ions, the ion number ratio of the medium-radius metal ions to the small-radius metal ions is defined as a first number ratio, and the first number ratio in the first compressive stress layer is smaller than the first number ratio in the second compressive stress layer and smaller than the first number ratio in the third compressive stress layer.

4. The glass of claim 3, wherein the metal ions further comprise large radius metal ions, and wherein a second ratio of numbers of the large radius metal ions to the medium radius metal ions is defined as a second ratio, the second ratio in the first compressive stress layer being less than or equal to the second ratio in the second compressive stress layer < the second ratio in the third compressive stress layer.

5. The glass of claim 4, wherein the small radius metal ions, the medium radius metal ions, and the large radius metal ions are each independently selected from alkali metal ions.

6. The glass of claim 3, wherein a compressive stress profile of the compressive stress layer has a first segment, a second segment, and a third segment in a direction from an outer surface of the compressive stress layer toward an interior of the glass, wherein a junction of the first segment and the second segment has a first inflection point, and wherein a junction of the second segment and the third segment has a second inflection point.

7. The glass of claim 6, wherein the compressive stress at the first inflection point is from 500 to 900MPa and the compressive stress at the second inflection point is from 50 to 300 MPa.

8. The glass of claim 6, wherein the depth of the first inflection point is between 0.05% and 0.5% of the thickness of the glass and the depth of the second inflection point is between 0.5% and 5% of the thickness of the glass.

9. The glass of claim 6, wherein the slope of the compressive stress profile is negative and the slope of the first segment < the slope of the second segment < the slope of the third segment.

10. A method of making glass comprising:

performing primary strengthening treatment on the glass substrate by using first molten salt;

performing secondary strengthening treatment on the glass substrate subjected to the primary strengthening treatment by using second molten salt;

performing third strengthening treatment on the glass substrate subjected to the second strengthening treatment by using third molten salt;

wherein the average ionic radius of the metal ions in the first molten salt < the average radius of the metal ions in the second molten salt < the average radius of the third metal ions in the molten salt.

11. The method according to claim 10, characterized in that the first molten salt, the second molten salt and the third molten salt satisfy any one of the following conditions:

(1) the first molten salt, the second molten salt and the third molten salt all contain small-radius metal salts and medium-radius metal salts at the same time, and the mass/(mass of the medium-radius metal salt + mass of the small-radius metal salt) of the medium-radius metal salts is defined as a first ratio, wherein the first ratio in the first molten salt is less than the first ratio in the second molten salt is less than the first ratio in the third molten salt;

(2) the first molten salt only contains the small-radius metal salt, the second molten salt and the third molten salt both contain the small-radius metal salt and the medium-radius metal salt, and the first proportion in the second molten salt is less than the first proportion in the third molten salt;

(3) the first molten salt only contains the small-radius metal salt, the second molten salt contains the small-radius metal salt and the medium-radius metal salt at the same time, and the third molten salt only contains the medium-radius metal salt;

(4) the first molten salt only contains the small-radius metal salt, the second molten salt contains the small-radius metal salt and the medium-radius metal salt at the same time, and the third molten salt contains the medium-radius metal salt and the large-radius metal salt;

(5) the first molten salt only contains the small-radius metal salt, the second molten salt only contains the medium-radius metal salt, and the third molten salt contains the medium-radius metal salt and the large-radius metal salt;

(6) the first molten salt contains only the small-radius metal salt, the second molten salt contains only the medium-radius metal salt, and the third molten salt contains only the large-radius metal salt.

12. The method of claim 11, wherein the small radius metal salt, the medium radius metal salt, and the large radius metal salt are each independently selected from alkali metal salts.

13. The method of claim 10, wherein the time of the first enhancement treatment > the time of the second enhancement treatment > the time of the third enhancement treatment.

14. The method according to claim 11, wherein the first strengthening treatment is performed for 60 to 240 minutes;

the time of the second strengthening treatment is 20-40 minutes;

the time of the third strengthening treatment is 2-10 minutes.

15. A housing component, characterized in that at least a part is made of a glass according to any one of claims 1-9.

16. An electronic device comprising the housing assembly of claim 15.

Technical Field

The invention relates to the technical field of glass, in particular to glass, a preparation method of the glass, a shell assembly and electronic equipment.

Background

At present, the front and back cover glass used by a mobile phone or a tablet personal computer adopts a chemical strengthening mode to improve the anti-falling property of the glass. The main reason for glass breakage is that under the action of breaking tensile stress, chemical strengthening can form a compressive stress layer on the surface of glass, so that a part of breaking tensile stress is offset when the glass falls, and the purpose of reducing the risk of glass falling breakage is achieved. At present, chemical strengthening in the industry has two modes, namely first-stage strengthening and second-stage strengthening. However, in the single-stage strengthening process, only one ion exchange is performed, so that the depth of the compressive stress layer of the glass is shallow, the penetration depth of the resistant foreign matters is small, and the glass is easy to crack. The two-stage strengthening process improves the depth of the compressive stress layer on the basis of the one-stage strengthening process, can resist the penetration of deeper foreign matters, but has no obvious improvement on the properties of bending fracture, blunt object impact fracture (such as steel ball impact) and the like of the glass because the magnitude of the compressive stress on the surface of the glass is not improved qualitatively.

Thus, the current glass-related art still remains to be improved.

Disclosure of Invention

The present invention is directed to solving, at least to some extent, one of the technical problems in the related art. Therefore, an object of the present invention is to provide a glass with better strengthening effect.

In one aspect of the present application, a glass is provided. According to the embodiment of the application, the outer surface of the glass is provided with a compressive stress layer, and the surface compressive stress of the compressive stress layer is 900-1500 MPa. Compared with the tempered glass in the related technology, the surface compressive stress of the glass is obviously improved, and the performance of bending fracture, blunt object impact fracture (such as steel ball impact) and the like of the glass is effectively improved.

In another aspect of the present application, a method of making glass is provided. According to an embodiment of the application, the method comprises: performing primary strengthening treatment on the glass substrate by using first molten salt; performing secondary strengthening treatment on the glass substrate subjected to the primary strengthening treatment by using second molten salt; performing third strengthening treatment on the glass substrate subjected to the second strengthening treatment by using third molten salt; wherein an average ionic radius of the metal ions in the first molten salt < an average radius of the metal ions in the second molten salt < an average radius of the metal ions in the third molten salt. Therefore, the average ionic radius of the metal ions in the first molten salt, the second molten salt and the third molten salt is gradually increased, namely the proportion of the metal ions with larger ionic radius is gradually increased, and in the strengthening treatment process, along with the reduction of the depth of the glass, the metal ions with larger ionic radius which are exchanged into the glass are gradually increased, so that the surface compressive stress of the compressive stress layer can reach a larger value, and the bending rupture resistance and the impact resistance are effectively improved.

In another aspect of the present application, a housing assembly is provided. According to an embodiment of the application, at least a part of the housing assembly is made of the aforementioned glass. Therefore, the shell assembly has good blunt object impact resistance, bending fracture resistance and foreign object piercing resistance.

In another aspect of the present application, an electronic device is provided. According to an embodiment of the application, the electronic device comprises the housing assembly as described above. Therefore, the electronic equipment has better blunt object impact resistance, bending fracture resistance and foreign object piercing resistance, and has better use effect.

Drawings

FIG. 1 is a schematic cross-sectional view of a glass according to an embodiment of the present invention.

Fig. 2 is a schematic view of the distribution of metal ions inside the glass.

FIG. 3 is a schematic diagram of the ion exchange of glass.

FIG. 4 is a graph illustrating a stress distribution curve of a first strengthened glass according to one embodiment of the present disclosure.

FIG. 5 is a graph illustrating a stress distribution curve of a second strengthened glass according to one embodiment of the present disclosure.

FIG. 6 is a graph illustrating a stress distribution curve of a third strengthened glass according to one embodiment of the present disclosure.

FIG. 7 is a graph illustrating a partial actual stress profile of a glass after a first strengthening treatment in accordance with one embodiment of the present application.

FIG. 8 is a graph illustrating a stress distribution curve of a first strengthened glass according to another embodiment of the present disclosure.

Detailed Description

The following describes embodiments of the present invention in detail. The following examples are illustrative only and are not to be construed as limiting the invention. The examples, where specific techniques or conditions are not indicated, are to be construed according to the techniques or conditions described in the literature in the art or according to the product specifications. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available.

In one aspect of the present application, a glass is provided. According to the embodiment of the application, the outer surface of the glass is provided with a compressive stress layer, and the surface compressive stress of the compressive stress layer is 900-1500 MPa. (specifically, 900MPa, 950MPa, 1000MPa, 1050MPa, 1100MPa, 1150MPa, 1200MPa, 1250MPa, 1300MPa, 1350MPa, 1400MPa, 1450MPa, 1500MPa, etc.). Compared with the tempered glass in the related technology, the surface compressive stress of the glass is obviously improved, and the performance of bending fracture, blunt object impact fracture (such as steel ball impact) and the like of the glass is effectively improved.

Further, the depth of compressive stress layer DOC of the glass is 10% to 25% (specifically, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, etc.) of the thickness H of the glass. Therefore, the depth of the compression stress layer of the glass is larger, and the glass can have larger foreign matter piercing resistance depth and better foreign matter piercing resistance.

Specifically, referring to fig. 1, the outer surface of the glass 100 has a compressive stress layer, the compressive stress layer includes a first compressive stress layer 11, a second compressive stress layer 12 and a third compressive stress layer 13 which are sequentially arranged from inside to outside, the compressive stress layer contains metal ions, the metal ions include small-radius metal ions and medium-radius metal ions, an ion number ratio of the medium-radius metal ions to the small-radius metal ions is defined as a first ratio, and the first ratio in the first compressive stress layer 11 is smaller than the first ratio in the second compressive stress layer 12 and smaller than the first ratio in the third compressive stress layer 13. Therefore, the number of ions with large ionic radius in the third pressure stress layer is more, the trend of outward expansion is stronger, the surface pressure stress of the outer surface of the glass is larger, the performances of impact resistance and bending fracture resistance are better, and the pressure stress of the second pressure stress layer and the pressure stress of the first pressure stress layer are gradually reduced, so that the glass does not explode automatically due to overlarge central tensile stress.

It can be understood that the introduction of metal ions into the glass can be performed by chemical strengthening, specifically, the chemical strengthening is performed by putting the glass with cut and polished appearance into high-temperature chemical molten salt, performing ion diffusion exchange by means of ion concentration difference, and exchanging large ion radius ions 2 in the molten salt for small ion radius ions 1 of the glass (refer to fig. 2 and 3, the left graph in fig. 3 is a schematic diagram before ion exchange, and the right graph is a schematic diagram after ion exchange), because the large ion radius ions 2 have larger size, they enter the glass and generate extrusion, the glass has a tendency of size expansion, generally the large ion radius ions 2 can only penetrate into the glass to a certain depth, and cannot penetrate after the depth, so the inside of the glass has no ion extrusion, and in a state of being pulled outward by the external glass, the glass generates a force of pulling inward to the external glass (i.e. the penetration depth area of the large ion radius ions 2), namely, the outer region generates compressive stress; while the outer portion of the glass has a tendency to swell, which has a tendency to pull the inner glass outward, i.e., the inner (i.e., the large ionic radius ion 2 impermeable region) glass is subjected to tensile stress. The glass basically breaks at the beginning of the surface layer and under the action of external tensile stress, so that after the surface layer of the glass is applied with compressive stress, a part of the external tensile stress can be offset, and the risk of glass breakage is reduced.

It should be noted that "metal ions" herein refers to metal ions that can permeate into the glass through ion exchange, for example, potassium ions in molten salt enter the glass and sodium ions in the glass are exchanged during chemical strengthening, and then the metal ions refer to potassium ions; if the sodium ions in the molten salt enter the glass and exchange the lithium ions in the glass, the metal ions refer to the sodium ions; if both sodium and potassium ions enter the glass by ion exchange, the metal ions are referred to as potassium and sodium ions. Herein, the small-radius metal ions have an ionic radius smaller than that of the medium-radius metal ions, and the medium-radius metal ions have an ionic radius smaller than that of the large-radius metal ions. In addition, the terms "first", "second" and "first" are used herein for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

Specifically, the metal ions may further include large-radius metal ions, a number ratio of the large-radius metal ions to the medium-radius metal ions is defined as a second ratio, and the second ratio in the first compressive stress layer is not greater than the second ratio in the second compressive stress layer and is less than the second ratio in the third compressive stress layer. Therefore, the surface compressive stress of the outer surface of the glass can be further improved by adopting metal ions with larger ionic radius, and the using effect of the glass is further improved.

Specifically, the specific distribution of the small-radius metal ions, the medium-radius metal ions, and the large-radius metal ions in the compressive stress layer is not limited. In the actual treatment process, the metal ions with small radius can generally penetrate into the glass to a deeper depth due to higher exchange activity, so that the glass has a deeper compressive stress layer depth, while the metal ions with larger radius can provide a larger compressive stress to enable the glass to have higher bending fracture resistance and blunt object impact resistance, and the exchange activity is gradually reduced along with the gradual increase of the radius of the ions, so that the depth of the glass capable of penetrating into the glass is gradually reduced. In some embodiments, the first compressive stress layer may contain only small-radius metal ions, and the second compressive stress layer and the third compressive stress layer may contain both small-radius metal ions and medium-radius metal ions, but the medium-radius metal ions in the third compressive stress layer have a higher proportion.

In some embodiments, the small radius metal ions, the medium radius metal ions, and the large radius metal ions are each independently selected from alkali metal ions. For example, the small-radius metal ions can be sodium ions and can exchange with lithium ions in the glass; the medium radius metal ions may be potassium ions that may be exchanged for lithium and sodium ions in the glass, and the large radius metal ions may be at least one of rubidium, cesium, and francium ions that may be exchanged for lithium, sodium, and potassium ions in the glass. Of course, the small-radius metal ions may also be potassium ions, and the medium-radius metal ions and the large-radius metal ions may be alkali metal ions with successively increasing radii, which is not described herein in detail. Specifically, sodium ions can typically penetrate into the glass to a depth of over 100 microns, potassium ions can penetrate into the glass to a depth of about 3-30 microns, and rubidium, cesium, and francium ions can penetrate into the glass to a depth of about 0.8-8 microns. The skilled person can flexibly select the required conditions according to the actual needs.

Specifically, in the direction from the outer surface of the compressive stress layer to the inside of the glass, the compressive stress distribution curve of the compressive stress layer 10 is divided into a first section ab, a second section bc and a third section cd, a first inflection point b is arranged at the joint of the first section ab and the second section bc, and a second inflection point c is arranged at the joint of the second section bc and the third section cd (the schematic diagram of the stress distribution curve refers to fig. 6, and the left and right vertical coordinates in the figure, one is the front surface of the glass, the other is the back surface of the glass, and the stress distribution on the front and back surfaces of the glass is the same). Therefore, the glass can have higher surface compressive stress and larger depth of the compressive stress layer, can resist the penetration of deeper foreign matters, and can effectively improve the bending resistance and blunt object impact resistance of the glass.

It should be noted that, in the actual glass strengthening process, three sections of compressive stress curves are in gradual transition, that is, the three sections of compressive stress curves do not have an obvious boundary point as shown in fig. 6, and the first inflection point b and the second inflection point c are not point values that can be accurately located but a range value (a part of the compressive stress curve schematic diagram obtained by actual detection refers to fig. 7).

Specifically, the compressive stress at the first inflection point b is 500 to 900MPa (specifically, 500MPa, 600MPa, 700MPa, 800MPa, 900MPa, etc.), and the compressive stress at the second inflection point b is 50 to 300MPa (50MPa, 100MPa, 150MPa, 200MPa, 250MPa, 300MPa, etc.). Therefore, the compressive stress close to the inside of the glass is appropriate, so that the tensile stress inside the glass is also appropriate, the compressive stress can be well balanced, and the glass cannot be easily self-exploded due to overlarge tensile stress.

Specifically, the depth DOLb of the first inflection point b is 0.05% to 0.5% (specifically, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, etc.) of the thickness H of the glass, and the depth DOLc of the second inflection point c is 0.5% to 5% (specifically, 0.5%, 1%, 2%, 3%, 4%, 5%, etc.) of the thickness H of the glass. Therefore, the depth of the part with the largest compressive stress on the outer surface of the glass is smaller, the performance requirements of blunt object impact resistance and bending fracture resistance can be met, and meanwhile, the tensile stress in the glass is not too large, so that the glass has better self-explosion resistance.

Specifically, the slope of the compressive stress distribution curve is a negative value, and the slope of the first section ab is smaller than the slope of the second section bc and smaller than the slope of the third section cd. In some embodiments, when the depth unit is micrometer and the compressive stress unit is MPa, the slope of the first section of the stress curve is-2000 to-200, the slope of the first section ab may be-2000 to-200 (specifically, -2000, -1500, -1000, -500, -200, etc.), the slope of the second section bc may be-200 to-50 (specifically, -200, -150, -100, -50, etc.), and the slope of the third section cd may be-50 to-0.1 (specifically-50, -40, -30, -20, -10, -5, -1, -0.1, etc.). Therefore, the compressive stress is distributed in a three-section manner, and the average value of the stress of the first section close to the surface of the glass is high, but the descending speed is fastest along with the deepening of the depth; the mean value of the stress of the deeper second section is relatively lower, but the descending speed is the second order as the depth is deeper; the average value of the stress of the deepest third section is minimum, but the speed of the stress of the deepest third section descending along with the depth is also slowest; the stress distribution mode can not only ensure the higher surface compressive stress value of the outer surface, but also can not cause the internal tensile stress to be overlarge.

It is understood that the specific type of the glass is not particularly limited as long as the glass can be ion-exchanged, and examples include, but are not limited to, soda-lime glass or alumino-silica glass, such as DT-Pro glass by AGC, GG3 glass by corning, and the main glass components are silicon, calcium, sodium, aluminum, etc., wherein sodium is the ion-exchange component during strengthening; lithium aluminosilicate glasses, such as GG5 glass from Corning corporation and DT-Star glass from AGC corporation, have main components of silicon, calcium, aluminum, sodium and lithium, wherein sodium and lithium are used as ion exchange components during strengthening.

In another aspect of the present application, a method of making glass is provided. According to an embodiment of the application, the method comprises: performing primary strengthening treatment on the glass substrate by using first molten salt; performing secondary strengthening treatment on the glass substrate subjected to the primary strengthening treatment by using second molten salt; performing third strengthening treatment on the glass substrate subjected to the second strengthening treatment by using third molten salt; wherein an average ionic radius of the metal ions in the first molten salt < an average radius of the metal ions in the second molten salt < an average radius of the metal ions in the third molten salt. Therefore, the average ionic radius of the metal ions in the first molten salt, the second molten salt and the third molten salt is gradually increased, namely the proportion of the metal ions with larger ionic radius is gradually increased, so that the metal ions with larger ionic radius which are exchanged into the glass are gradually increased along with the reduction of the depth of the glass during the strengthening treatment process, the pressure stress distribution curve of the pressure stress layer is distributed in three sections, the surface pressure stress of the outer surface can reach a larger value, and the bending fracture resistance and the impact resistance are improved.

In the present specification, "small-radius metal salt" means that the metal ion in the metal salt has a small ionic radius, and specifically, the ionic radius of the metal ion in the small-radius metal salt < the ionic radius of the metal ion in the medium-radius metal salt < the ionic radius of the metal ion in the large-radius metal salt.

It can be understood that the method of the present application is mainly to strengthen the glass by ion exchange, and the metal ion exchange activity and strengthening effect of different radiuses are slightly different, specifically, in the three strengthening treatment processes, the ion exchange between the metal ions with small radius, the metal ions with medium radius and the metal ions with large radius in the molten salt and the metal ions in the glass can be carried out, in the specific strengthening treatment process, the metal ions with smaller radius, the metal ions with medium radius in the metal ion exchange glass with small radius and the metal ions with medium radius in the metal ion exchange glass with large radius can be carried out synchronously, on one hand, the metal ions with smaller radius in the metal ion exchange glass with small radius can exchange the metal ions with small radius more rapidly than the metal ions with medium radius due to smaller particle size, on the other hand, the concentration of the metal ions with different radii in the molten salt can be adjusted, to control the primary and secondary degree of metal ion exchange of different radii.

In some specific embodiments, the first molten salt, the second molten salt, and the third molten salt may each contain both a small-radius metal salt and a medium-radius metal salt, and a mass of the medium-radius metal salt/(a mass of the medium-radius metal salt + a mass of the small-radius metal salt) is defined as a first ratio, the first ratio in the first molten salt < the first ratio in the second molten salt < the first ratio in the third molten salt. Specifically, the first proportion in the first molten salt may be greater than 0 and less than or equal to 70% (specifically, e.g., 1%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, etc.), the first proportion in the second molten salt may be 3% to 20% (specifically, e.g., 3%, 4%, 5%, 8%, 10%, 12%, 15%, 18%, 20%, etc.), and the first proportion in the third molten salt may be 0% to 5% (specifically, e.g., 0%, 1%, 2%, 3%, 4%, 5%, etc.).

In other specific embodiments, the first molten salt may contain only the small-radius metal salt, the second molten salt and the third molten salt may contain both the small-radius metal salt and the medium-radius metal salt, and the first proportion in the second molten salt may be smaller than the first proportion in the third molten salt.

In other embodiments, the first molten salt may contain only the small radius metal salt, the second molten salt may contain both the small radius metal salt and the medium radius metal salt, and the third molten salt may contain only the medium radius metal salt.

In other embodiments, the first molten salt may contain only the small-radius metal salt, the second molten salt may contain both the small-radius metal salt and the medium-radius metal salt, and the third molten salt may contain both the medium-radius metal salt and the large-radius metal salt.

In other embodiments, the first molten salt may contain only the small-radius metal salt, the second molten salt may contain only the medium-radius metal salt, and the third molten salt may contain both the medium-radius metal salt and the large-radius metal salt.

In other embodiments, the first molten salt may contain only the small radius metal salt, the second molten salt may contain only the medium radius metal salt, and the third molten salt may contain only the large radius metal salt.

It can be understood that the molten salts in the different embodiments may have different compositions and proportions, and the specific types of the metal salts and the proportions of the metal salts with different radii may be flexibly adjusted according to the thickness, the target strength, and the like of the glass to obtain the desired use requirements, which is not described in detail herein.

Specifically, the time of the first strengthening treatment is longer than the time of the second strengthening treatment and longer than the time of the third strengthening treatment. Specifically, during the first strengthening treatment, the small-radius metal ions in the molten salt are mainly exchanged with the metal ions with the smaller radius in the glass to obtain a deeper strengthening depth, so that the concentration of the small-radius metal ions in the molten salt is relatively higher, and the strengthening time is longest; during the second strengthening treatment, the medium-radius metal ions in the molten salt are mainly exchanged with the small-radius metal ions in the glass to obtain high surface pressure stress, so that the concentration of the medium-radius metal ions in the molten salt is relatively high, and the strengthening time is relatively short; during the third strengthening treatment, the exchange proportion of the medium-radius metal ions in the molten salt and the small-radius metal ions in the glass is higher, and higher surface pressure stress is obtained, so that the concentration of the medium-radius metal ions in the molten salt is relatively higher, or the large-radius metal ions can be further introduced, and the strengthening time is relatively shorter. Therefore, the surface compressive stress CS of the glass can be effectively improved by adding the third strengthening treatment with high concentration for a short time, and the shorter time of the third strengthening treatment can prevent the strengthening treatment from being too long, so that the internal compressive stress of the glass after the first strengthening treatment and the second strengthening treatment is reduced too much (small-radius metal ions in the glass can continuously diffuse into the glass at high temperature during the third strengthening treatment, and at the moment, the small-radius metal ions in the molten salt are supplemented only slightly or even not, so that the internal compressive stress in the glass is reduced), and the excessive compressive stress generated by the third strengthening treatment is avoided, so that the glass spontaneous explosion risk is caused by the overlarge central tensile stress CT of the obtained glass.

Specifically, the first strengthening treatment may be performed for 60 to 240 minutes (specifically, 60 minutes, 70 minutes, 80 minutes, 100 minutes, 130 minutes, 140 minutes, 150 minutes, 160 minutes, 170 minutes, 180 minutes, 190 minutes, 200 minutes, 210 minutes, 220 minutes, 230 minutes, 240 minutes, and the like); the time of the second strengthening treatment may be 20 to 40 minutes (specifically, 20 minutes, 25 minutes, 30 minutes, 31 minutes, 32 minutes, 33 minutes, 34 minutes, 35 minutes, 40 minutes, and the like); the time of the third strengthening treatment may be 2 to 10 minutes (specifically, 2 minutes, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, etc.).

It can be understood that the types, specific proportions, processing times, types, thicknesses, and the like of the metal ions with different ion radii in the three specific strengthening treatment processes can be adjusted according to actual conditions and performance requirements of the glass, and are not described in detail herein.

Specifically, taking the example that the first molten salt, the second molten salt and the third molten salt all contain small-radius metal salt and medium-radius metal salt at the same time as follows:

after the first strengthening treatment, the pressure stress distribution curve in the glass refers to fig. 4 (the pressure stress on the front surface and the back surface of the glass is symmetrically distributed, and the distribution state of only one surface is described below), the pressure stress distribution is in a two-section type, an inflection point exists, the pressure stress closer to the outer surface of the glass is mainly generated by the exchange of metal ions with medium radius and metal ions with small radius before the inflection point, the stress value is large, but the descending speed is fast along with the increase of the depth of the glass; the stress after the inflection point is generated by the exchange of the metal ions with small radius and the metal ions with smaller radius in the glass, and the stress value is lower but the descending speed is slow along with the increase of the depth of the metal ions penetrating into the glass. The range of the surface compressive stress value CS of the glass can be 200-600 MPa, the depth DOL of an inflection point can be 0.5-5% of the thickness of the glass, the compressive stress CSk of the inflection point can be 50-300 MPa, and the depth DOC of the compressive stress layer is 10-25% of the thickness of the glass.

After the second strengthening treatment, the strengthening stress distribution in the glass is shown in fig. 5 (the compressive stress on the front and back surfaces of the glass is symmetrically distributed, and the distribution state of only one surface is described below): the pressure stress distribution curve is in a two-section type, an inflection point exists, but after the first strengthening treatment, the surface pressure stress CS of the glass is obviously improved under the exchange and extrusion effects of high-concentration medium-radius metal ions, the surface pressure stress value CS of the glass can be 600-1200 MPa, the depth DOL of the inflection point can be 0.5-5% of the thickness of the glass, the pressure stress CSk of the inflection point can be 50-300 MPa, and the depth DOC of the pressure stress layer can be 10-25% of the thickness of the glass.

After the third strengthening treatment, the strengthening stress distribution curve in the glass is shown in fig. 6 (the compressive stress of the front surface and the back surface of the glass are symmetrically distributed, and the distribution state of only one surface is described below): because the concentration of the medium-radius metal ions in the molten salt is extremely high, the medium-radius metal ions exchange with the small-radius metal ions on the surface layer of the glass to generate very high surface compressive stress on the surface of the glass, the compressive stress distribution curve is in a three-section type and has two inflection points b and c, the first section has the highest compressive stress and is fastest to decrease along with the increase of the depth of the medium-radius metal ions penetrating into the glass, the range of the surface compressive stress CS of the glass can be 900-1500 MPa, the depth DOLb of the inflection point b can be 0.05-0.5% of the thickness of the glass, and the compressive stress CSKb at the inflection point b can be 500. The descending speed of the second section of pressure is slower than that of the first section of pressure along with the increase of the depth of the second section of pressure penetrating into the glass, the depth DOLc of the inflection point c can be 0.5-5% of the thickness of the glass, and the pressure stress CSKc at the inflection point c can be 50-300 MPa. The third section has the smallest compressive stress, the descending speed of the third section is slowest along with the increase of the depth of the third section into the glass, and the DOC of the depth of the compressive stress layer can be 10-25% of the thickness of the glass.

It can be understood that if the first strengthening treatment uses a molten salt containing only small-radius metal ions, the compressive stress distribution curve of the glass after the first strengthening treatment can be referred to in fig. 8, and specifically, since only the small-radius metal ions and the metal ions with smaller radius in the glass are exchanged, the stress distribution curve has no inflection point and is a straight line.

In one embodiment, corning GG5 glass is taken as an example: when the thickness of the glass is 0.55mm, the molten salt proportion of the first strengthening treatment can be 38 wt% of NaNO₃And 62 wt% of KNO₃Strengthening at 380 deg.c for 130 min; the molten salt proportion of the second strengthening treatment can be 9 wt% of NaNO₃And 91 wt% KNO₃Strengthening for 30 minutes at 380 ℃; the molten salt proportion of the third strengthening treatment can be 100 percent KNO₃And strengthening at 380 deg.c for 5 min.

In another embodiment, when the glass thickness is 0.8mm, the molten salt composition of the first strengthening treatment can be 75 wt% of NaNO₃And 25 wt% of KNO₃Strengthening at 380 deg.c for 240 min; the molten salt proportion of the second strengthening treatment can be 9 wt% of NaNO₃And 91 wt% KNO₃Strengthening at 380 deg.c for 35 min; the molten salt proportion of the third strengthening treatment can be 100 percent KNO₃And strengthening at 380 deg.C for 3 min. The surface stress CS of a finished product is improved to 1100MPa from about 800MPa of the conventional two-stage strengthening, the 32g falling ball impact failure height of the glass is improved to 130cm from the conventional average value of 100cm, and the four-axis bending strength of the glass is improved to 805MPa from the conventional average value of 700 MPa.

In some embodiments, the small radius metal salt, the medium radius metal salt, and the large radius metal salt may each independently be selected from alkali metal salts, such as: the small radius metal salt comprises sodium nitrate; the medium-radius metal salt comprises potassium nitrate; the large radius metal salt includes at least one of rubidium nitrate, cesium nitrate, and francium nitrate. Of course, the small-radius metal salt may also be potassium nitrate, and the medium-radius metal salt and the large-radius metal salt may be base metal salts in which the radius of the metal ions gradually increases, which is not described in detail herein.

According to the method, high-concentration metal ions with larger radius are used for generating higher surface compressive stress CS on the surface of the glass in a third strengthening mode, so that the strength of the glass is improved. Meanwhile, the depth of the first section of compressive stress is controlled within a shallow range of the thickness of the glass by controlling the time of third strengthening, and the total amount of the compressive stress increased relative to the secondary glass is also small due to the small depth of the high-pressure stress region, so that the increase amplitude of the central tensile stress CT of the glass is small while the surface stress CS of the glass is improved, and the risk of spontaneous explosion caused by overlarge CT is avoided.

In another aspect of the present application, a housing assembly is provided. According to an embodiment of the application, at least a part of the housing assembly is made of the aforementioned glass. Therefore, the shell assembly has good blunt object impact resistance, bending fracture resistance and foreign object piercing resistance.

Specifically, the specific shape, size, and the like of the housing assembly are not particularly limited, and may be a flat plate structure, a 2.5D structure, or a 3D structure, and the specific size may be adjusted according to the applied electronic device, which is not described herein any more. It will be appreciated that the housing assembly may be formed in part from the glass described above, for example, the housing assembly may include a bottom surface and at least one side surface connected to the bottom surface, in which case both the bottom surface and the side surface may be formed from the glass described above, or one of the bottom surface or the side surface may be formed from glass and the other may be formed from other materials such as ceramic, polymer, etc. It is understood that the housing assembly may serve as a front cover or a back cover of the electronic device.

In another aspect of the present application, an electronic device is provided. According to an embodiment of the application, the electronic device comprises the housing assembly as described above. Therefore, the electronic equipment has better blunt object impact resistance, bending fracture resistance and foreign object piercing resistance, and has better use effect.

Specifically, the specific type of the electronic device is not particularly limited, and may be, for example, a mobile phone, a tablet computer, a wearable device, a game machine, various appliances for daily use, and the like. In addition, it can be understood that, in addition to the aforementioned housing component, the electronic device may further include other structures and components necessary for a conventional electronic device, for example, a mobile phone, a display module, a touch module, a memory, a motherboard, a fingerprint module, a camera module, a sound system, and the like, which are not described in detail herein.

Embodiments of the present application are described in detail below.