CN113582558A

CN113582558A - Glass strengthening method, glass, case assembly, and electronic device

Info

Publication number: CN113582558A
Application number: CN202110978516.3A
Authority: CN
Inventors: 夏阳阳
Original assignee: Guangdong Oppo Mobile Telecommunications Corp Ltd
Current assignee: Guangdong Oppo Mobile Telecommunications Corp Ltd
Priority date: 2021-08-24
Filing date: 2021-08-24
Publication date: 2021-11-02

Abstract

The application discloses a glass strengthening method, glass, a shell assembly and an electronic device. The glass strengthening method comprises the following steps: performing primary strengthening on the glass substrate by using first molten salt; and performing secondary strengthening on the glass substrate subjected to the primary strengthening by using second molten salt. The first molten salt and the second molten salt both comprise first metal ions and second metal ions, the proportion of the first metal ions in the first molten salt is larger than that in the second molten salt, the proportion of the second metal ions in the first molten salt is smaller than that in the second molten salt, the proportion of the first metal ions in the second molten salt is 1% -3%, and the proportion of the second metal ions in the second molten salt is 97% -99%. Therefore, the surface compressive stress value of the glass substrate after being strengthened twice can be improved, and the strength performance of the glass substrate is effectively improved.

Description

Glass strengthening method, glass, case assembly, and electronic device

Technical Field

The present application relates to the field of glass technologies, and in particular, to a glass strengthening method, glass, a housing assembly, and an electronic device.

Background

In the related art, in order to improve the strength of the glass cover plate, the glass rear cover of an electronic product such as a mobile phone and the like can be reinforced twice to improve the strength of the glass, however, the improvement of the surface strength of the glass by the existing parameters of secondary reinforcement is limited, and certain limitations still exist.

Disclosure of Invention

The embodiment of the application provides a glass strengthening method, glass, a shell assembly and an electronic device.

The glass strengthening method of the embodiment of the application comprises the following steps:

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

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

wherein each of the first molten salt and the second molten salt includes a first metal ion and a second metal ion, an ionic radius of the first metal ion is smaller than an ionic radius of the second metal ion, a proportion of the first metal ion in the first molten salt is larger than a proportion of the first metal ion in the second molten salt, and a proportion of the second metal ion in the first molten salt is smaller than a proportion of the second metal ion in the second molten salt;

the proportion of the first metal ions in the second molten salt is 1% -3%, and the proportion of the second metal ions in the second molten salt is 97% -99%.

In the glass strengthening method of the embodiment of the present application, the glass substrate may be strengthened twice in sequence by using a first molten salt and a second molten salt, both the first molten salt and the second molten salt include a first metal ion and a second metal ion, an ionic radius of the first metal ion is smaller than an ionic radius of the second metal ion, a proportion of the first metal ion in the first molten salt is larger than a proportion of the first metal ion in the second molten salt, and a proportion of the second metal ion in the first molten salt is smaller than a proportion of the second metal ion in the second molten salt; the proportion of the first metal ions in the second molten salt is 1% -3%, and the proportion of the second metal ions in the second molten salt is 97% -99%. Therefore, the surface compressive stress value of the glass substrate after being strengthened twice can be improved, and the strength performance of the glass substrate is effectively improved.

The embodiment of the application provides glass which is prepared by the glass strengthening method

The embodiment of the application provides a shell component, and the shell component comprises the glass.

The embodiment of the application also provides an electronic device, and the electronic device comprises the shell assembly.

Additional aspects and advantages of the present application will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the present application.

Drawings

The above and/or additional aspects and advantages of the present application will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a schematic flow diagram of a glass strengthening method according to an embodiment of the present application;

FIG. 2 is a schematic flow chart of a glass strengthening method according to an embodiment of the present application;

FIG. 3 is a schematic view of another process of the glass strengthening method according to the embodiment of the present application;

fig. 4 is a schematic perspective view of an electronic device according to an embodiment of the present application.

Detailed Description

Reference will now be made in detail to embodiments of the present application, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative and are only for the purpose of explaining the present application and are not to be construed as limiting the present application.

The following disclosure provides many different embodiments or examples for implementing different features of the application. In order to simplify the disclosure of the present application, specific example components and arrangements are described below. Of course, they are merely examples and are not intended to limit the present application. Moreover, the present application may repeat reference numerals and/or letters in the various examples, such repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. In addition, examples of various specific processes and materials are provided herein, but one of ordinary skill in the art may recognize applications of other processes and/or use of other materials.

Referring to fig. 1, a glass strengthening method according to an embodiment of the present disclosure includes:

s10: performing primary strengthening on the glass substrate by using first molten salt;

s20: performing secondary strengthening on the glass substrate subjected to the primary strengthening by using second molten salt;

the first molten salt and the second molten salt both comprise first metal ions and second metal ions, the ionic radius of the first metal ions is smaller than that of the second metal ions, the proportion of the first metal ions in the first molten salt is larger than that of the first metal ions in the second molten salt, and the proportion of the second metal ions in the first molten salt is smaller than that of the second metal ions in the second molten salt;

It is understood that the glass may be chemically strengthened by the introduction of metal ions into the glass. The chemical strengthening is a process in which a glass substrate is put into a high-temperature chemical molten salt, ion diffusion exchange is performed by an ion concentration difference, and ions with a large ionic radius in the molten salt are exchanged for ions with a small ionic radius in the glass.

Because the ion with large ionic radius has larger size, the ion enters the glass to generate extrusion, the glass has the tendency of size expansion, generally, the ions with large ionic radius can only penetrate into the glass to a certain depth, and can not penetrate after the ion with large ionic radius exceeds the certain depth, so that the ion extrusion is not generated in the glass, and the glass is in a state of being pulled outwards by external glass, and generates a force of pulling inwards on the external glass (namely an ion penetration area with large ionic radius), namely, the external area 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 ion-impermeable region of large ionic radius) glass is subjected to tensile stress. The glass basically breaks at the beginning of the surface layer and breaks under the action of external tensile stress, so that after the surface layer of the glass is applied with compressive stress, a part of external tensile stress can be offset, and the risk of glass breakage is reduced.

Specifically, in the present application, the first molten salt and the second molten salt each include a first metal ion and a second metal ion, and both the first metal ion and the second metal ion can penetrate into the inside of the glass substrate and be replaced with a metal ion with a small ionic radius inside the glass substrate, and the ratio of the first metal ion and the second metal ion in the first molten salt and the second molten salt can be reasonably configured and adjusted to increase the surface compressive stress value of the glass substrate, so that the glass can have higher bending fracture resistance and blunt object impact resistance, and the strength performance of the glass substrate is improved.

Preferably, the first metal ion and the second metal ion may be alkali metal ions, such as lithium ions, sodium ions, potassium ions, rubidium ions, cesium ions, francium ions. The ionic radius of the first metal ions is smaller than that of the second metal ions, and when the first metal ions are lithium ions, the second metal ions can be sodium ions or potassium ions and the like; when the first metal ion is a sodium ion, the second metal ion may be a potassium ion or a rubidium ion. The present application does not limit the kinds of the first metal ion and the second metal ion.

The metal ions in the molten salt cannot exist independently in the form of ions, and can exist in the molten salt in a mode of combining with acid radical ions, so that the metal ions can be exchanged with the ions in the glass substrate at high temperature. For example, the first metal ion and the second metal ion may be present in the first molten salt and the second molten salt by combining with a nitrate ion, a sulfate ion, or the like. Correspondingly, the first molten salt and the second molten salt may be lithium nitrate, sodium nitrate, potassium nitrate, or the like, or a mixture of lithium sulfate, sodium sulfate, potassium sulfate, or the like. The application is not limited to the kind of the acid radical ion combined with the metal ion.

In the actual treatment process, metal ions with small ion radius have high exchange activity and can generally penetrate into a deeper position of the glass, the exchange activity of the metal ions is gradually reduced along with the gradual increase of the ion radius, and the depth capable of penetrating into the glass is gradually reduced, namely the exchange depth of the metal ions with smaller ion radius and the ions in the glass is deeper, so that the glass has a deeper compressive stress depth. For example, sodium ions can typically penetrate into the glass to a depth of more than 100 microns, while potassium ions can penetrate into the glass to a depth of about 3 to 30 microns. Meanwhile, the compressive stress provided by the metal with large ionic radius is large, and the metal ions with large ionic radius are exchanged with the metal ions on the superficial layer of the surface of the glass, so that the surface of the glass substrate can have large compressive stress, and the glass substrate can have high bending fracture resistance and blunt object impact resistance in depth and surface layers, and the strength performance of the glass is greatly improved.

In the present application, the specific type of the glass substrate is not particularly limited as long as it is a glass capable of ion exchange, and for example, the glass substrate may be a lithium aluminosilicate glass such as GG5 glass by corning corporation or DT-Star glass by AGC corporation, the main components of which are silicon, calcium, aluminum, sodium, and lithium, with sodium and lithium as ion exchange components at the time of strengthening. Taking the glass substrate as lithium aluminum silicate glass, the first metal ions as sodium ions, and the second metal ions as potassium ions as examples, in the present application, in the first strengthening process, mainly the sodium ions in the first molten salt exchange with the lithium ions in the glass substrate to form a Na-Li exchange layer, and in the second strengthening process, mainly the potassium ions in the second molten salt exchange with the sodium ions in the glass substrate after the first strengthening to form a K-Na exchange layer.

It should be noted that, in the present application, the "proportion of the first metal ion" refers to a proportion of the first metal ion in all metal ions, that is, a ratio of the number of the first metal ion to a sum of the values of the first metal ion and the second metal ion, and similarly, the "proportion of the second metal ion" refers to a proportion of the second metal ion in all metal ions, that is, a ratio of the number of the second metal ion to a sum of the values of the first metal ion and the second metal ion.

In the embodiment of the present application, when the second strengthening is performed, the second metal ions in the second molten salt account for 97% to 99%, and for example, when the second metal ions are potassium ions, the concentration ratio of the potassium ions is large, and the surface compressive stress value (that is, CS value) of the glass substrate can be improved more favorably.

In some embodiments, the glass substrate after the second strengthening has a surface compressive stress value (CS value) in the range of 900MPa to 1250 MPa. For example, the surface compressive stress value of the glass substrate strengthened by the glass strengthening method of the present application may be 950MPa, 1000MPa, 1150MPa, 1200MPa, or the like. Compared with the strengthened glass substrate in the prior art, the surface compressive stress value of the glass substrate is greatly improved, and the strength performance of the glass substrate is effectively improved. Of course, the proportion of the first metal ions and the second metal ions in the first molten salt and the second molten salt can be further adjusted according to actual conditions and then strengthened, so that the glass substrate with higher surface compressive stress can be obtained, and the surface compressive stress value of the glass substrate is not limited.

In certain embodiments, the first molten salt has a first metal ion content of 38% and the first molten salt has a second metal ion content of 62%.

Therefore, the first metal ions and the second metal ions in the first molten salt can be properly proportioned so that the first metal ions can be exchanged with the metal ions in the glass substrate in the first strengthening process to form a first exchange stress layer with a larger thickness.

In particular, in the present application, a first molten salt is used for a first strengthening, which may be performed at a temperature of 380 ℃. The first metal ions have smaller ion radius and higher exchange activity, and can penetrate into deeper positions in the glass to exchange deeper metal ions in the glass, for example, lithium ions in the glass substrate can be exchanged through sodium ions, so that the glass substrate is preliminarily strengthened to obtain a first exchange stress layer with a deeper thickness, the surface compressive stress value of the glass substrate after the preliminary strengthening can reach 480-630MPa, and the Depth (DOC) of the first exchange stress layer can be 90-105 μm taking the first stress exchange layer as an Na-Li exchange layer as an example. It can be understood that, during the first strengthening process, since the ratio of the first metal ions is moderate and the radius of the first metal ions is smaller than that of the second metal ions, the first metal ions are mainly exchanged with the metal ions in the glass substrate during the first strengthening. In the second strengthening, the ratio of the second metal ions is greatly increased, and the ratio of the first metal ions is very small, at this time, the first metal ions are mainly exchanged with the metal ions in the glass substrate (for example, the second metal ions are exchanged with the first metal ions in the glass substrate after the first strengthening), so as to form a second stress exchange layer, and taking the second stress exchange layer as a K-Na exchange layer as an example, the depth of the second stress exchange layer (DOL) can be 7-9.5 um.

In the present application, the ratio of the first metal ions in the second molten salt is 1% to 3%, and the ratio of the second metal ions in the second molten salt is 97% to 99%. Preferably, the proportion of the first metal ions in the second molten salt may be greater than 1% and less than or equal to 3%, and the proportion of the second metal ions may be greater than or equal to 97% and less than 99%. For example, the ratio of the first metal ion in the second molten salt is 3%, and the ratio of the second metal ion is 97%; the proportion of the first metal ions is 1.1%, and the proportion of the second metal ions is 98.9%.

It is understood that the second molten salt is used for the second strengthening, which can also be performed at a temperature of 380 ℃. Compared with the first molten salt, the first metal ions in the second molten salt have a smaller proportion, and the second metal ions have a larger proportion. The second metal ions are further exchanged with metal ions in the glass substrate, wherein the second metal ions can be exchanged even with the first metal ions exchanged in the first strengthening. The second metal ions have larger ion radius, and are extruded with other ions after entering the glass substrate, so that the surface compressive stress value of the glass substrate is further enhanced.

It is to be understood that the present application is not limited to the ratio of the first metal ion to the second metal ion in the first molten salt and the second molten salt, and only needs to satisfy the above range.

In some embodiments, the treatment time for the first fortification is 125 minutes.

Therefore, a deeper stress exchange layer and a primary promotion to the surface compressive stress value of the glass substrate can be obtained during the first strengthening by reasonably setting the time of the first strengthening treatment.

Specifically, during the first strengthening treatment, the first metal ions in the molten salt are mainly exchanged with the metal ions with smaller radius in the glass to obtain deeper strengthening depth, the concentration of the metal ions with smaller radius in the molten salt is relatively higher, and the strengthening depth and the surface compressive stress value can be improved by adopting longer strengthening time.

In certain embodiments, the treatment time for the second fortification is 20 to 30 minutes.

Therefore, the surface compressive stress value can be further increased to 900MPa-1250MPa on the basis of the first strengthening by reasonably setting the time of the second strengthening treatment, and the glass substrate does not crack due to the overlarge central tensile stress value (CT value) of the glass substrate.

Specifically, during the second strengthening treatment, the second metal ions in the molten salt are mainly exchanged with the small-radius metal ions in the glass to obtain a high surface compressive stress value, and the concentration of the second metal ions in the second molten salt is relatively high.

It is understood that, during the second strengthening reaction, the concentration of the first metal ions is gradually reduced, so that the surface compressive stress value (CS value) of the glass is increased, the depth of compressive stress layer (DOL) is increased, and the inflection point stress value (CSK value) is decreased. As the reaction time decreases, the CS value of the glass increases, the DOL decreases, and the CSK increases. Therefore, the decrease in the concentration of the first metal ion in the second molten salt in the second strengthening reaction process leads to a lower CSK limit of the strengthened glass (the lower CSK limit causes a decrease in the strength corresponding to the same stress layer, and the glass strength also decreases). Therefore, in order to avoid the problem in the second strengthening, the second strengthening time is not required to be too long, and the CSK of the glass in the second strengthening can be improved by controlling the second strengthening time within 20-30 minutes, so that the stability of the glass strength is ensured.

In some embodiments, the glass substrate after the first strengthening has a central tensile stress of 44MPa to 98MPa and the glass substrate after the second strengthening has a central tensile stress of 44MPa to 100 MPa.

Thus, the central tensile stress of the glass is relatively stable in the strengthening process, so that the self-explosion caused by the overlarge tensile stress of the glass is prevented.

Specifically, according to the chemical tempered glass and the surface and edge theoretical strength formula CS × DOL ═ CT × (H-2DOL), H is the thickness of the glass substrate, from which it can be concluded: when the thickness and the material of the glass are determined, the intrinsic strength is determined, the overall strength of the glass is positively correlated with the surface Compressive Stress (CS) value, and the glass is negatively correlated with the crack state; the larger the CS value, the higher the glass surface and edge strength; according to the relation between CS and central tensile stress (CT) of the glass, the CT is increased in the CS increasing process, and the glass with too high CT has the risk of spontaneous explosion. In the embodiment of the present application, the reinforcement time of the second reinforcement is reduced and controlled within 25 ± 5 minutes, so that the CS value can be increased, and the DOL can be reduced, thereby ensuring that the CT value is substantially stable and unchanged, and avoiding the self-explosion caused by the excessively large CT value.

Referring to fig. 2, in some embodiments, prior to first strengthening the glass substrate with the first molten salt, the glass strengthening method further comprises:

s01: and performing fine polishing treatment on the glass substrate.

Therefore, the micro-cracks on the glass substrate can be repaired by fine polishing, so that the glass substrate has better strength before being reinforced for the first time, and the strength of molten salt reinforcement is enhanced.

Specifically, the polishing process is yet another means to increase the strength of the glass. There may be many micro cracks on the surface of the untreated glass substrate, and these micro cracks affect the strength of the glass to cause the glass to fail in strength.

It can be understood that, in the conventional process, before the glass substrate is strengthened for the first time, the glass substrate is usually subjected to side polishing, concave polishing and convex polishing, microcracks on the surface of the glass substrate are treated for the first time, so as to reduce the microcracks on the surface of the glass substrate and improve the surface strength of the glass substrate, and then the glass substrate enters a strengthening stage. However, in the present application, the above steps are to finish polish the glass substrate after these polishing stages, so as to make the microcrack treatment on the surface of the glass substrate more delicate, and finish polishing can be understood as a polishing process having better polishing effect than the above.

Specifically, the glass substrate can be polished by matching a sponge disc brush on a flat grinding machine, and the fine polishing time can be controlled between 1400s and 1600 s. The micro-cracks on the surface of the glass substrate can be finely treated and repaired by adopting the sponge disc brush to finely polish so as to enhance the strength of the glass substrate.

Referring to fig. 3, in some embodiments, after the step of performing the second strengthening on the glass substrate after the first strengthening by using the second molten salt, the glass strengthening method further includes:

s02: and performing back polishing treatment on the glass substrate subjected to secondary strengthening.

Therefore, the surface of the glass substrate after molten salt strengthening can be further strengthened by back polishing, and micro flaws on the surface of the glass substrate after pressurization are removed, so that the glass strength is improved.

In particular, back-polishing is understood to mean returning to the flat grinder or polisher for a re-polishing process during the strengthening process. After the glass substrate is strengthened for the second time, metal ions in the molten salt are exchanged with small-radius ions in the glass substrate, and the strength of the glass substrate is enhanced. The surface of the glass substrate may have some micro-defects, which may further strengthen the glass substrate through a back-polishing process.

In the application, the back polishing is carried out by a polyurethane brush matched with a flat grinding machine, and cerium oxide (CeO) can also be adopted for polishing in the fine polishing and the back polishing₂) Polishing solution in cerium oxide (CeO)₂) CeO under the action of polishing solution₂SiO hydrolyzed on glass surface by particles₃ ^-Ions are chemically adsorbed, CeO₂The particles and the surface of the glass form Ce-O-Si chemical bonds, and the glass is polished along with the breakage of the Si-O-Si bonds of the glass, so that micro defects on the surface of the pressurized glass are further removed, and the purpose of improving the strength is achieved.

In some embodiments, the polishing time for the back-polishing of the glass substrate after the second strengthening is 130-150 seconds.

Thus, the strength of the glass can be ensured by reasonably configuring the polishing time of the back polishing without strength reduction caused by excessive removal of the glass due to excessive polishing time.

Specifically, cerium oxide polishing has a good polishing effect, strong cutting force, long service life and high polishing precision, and the polishing time can be about 140 s. The polishing time is not suitable to be too long, the polishing time is too long, the surface of the glass is easily abraded to influence the strength of the glass, the polishing time is not too short, and the surface defects cannot be completely treated well due to too short polishing time, so that the polishing time is set to be 130-150 seconds, and both the polishing time and the polishing time can be considered.

In certain embodiments, the thickness of the back-polished glass substrate is from 0.46mm to 0.53 mm.

Therefore, the strength performance of the glass can be ensured under the condition that the thickness of the glass substrate is relatively thin.

It can be understood that at present, the glass rear cover in the mobile phone industry mainly uses the secondary strengthening corning GG5 material glass with the thickness of 0.55mm +0.03/-0.04mm, and with the continuous abundance and increase of the functions of the mobile phone, the stacking structure of the mobile phone is more challenged, and in addition, the light and thin flagship becomes a strong demand in the mobile phone industry due to the important consideration of the overall hand feeling of the mobile phone. Therefore, the need to reduce the thickness of the glass rear cover from the design end without sacrificing its strength is additionally important, however, the reduction of the glass thickness is at high risk of strength failure. In the embodiment of the application, the thickness of the glass can be reduced to 0.5mm and the strength performance of the glass can be ensured by optimizing the new strengthening parameters and improving the polishing process.

Specifically, after the back polishing treatment, the thickness of the glass substrate may be between 0.46mm and 0.53mm, such as 0.47mm, 0.48mm, 0.5mm, 0.51mm, 0.52mm, and the like, which may be determined according to the actual conditions of the ion ratio in the molten salt, the strengthening time, the temperature, the polishing time, the polishing material, and the like.

The present application provides a glass strengthened by the glass strengthening method according to any one of the above embodiments. The glass strengthened by the glass strengthening method has the advantages that the strength of the glass is improved, the thickness of the glass is reduced, the glass has better blunt object impact resistance, bending fracture resistance, foreign object piercing resistance and the like, and the application of the glass is wider. Specifically, the glass may be 2D plane glass, and may also be 2.5D or 3D glass, and is not limited herein.

Referring to fig. 4, a housing assembly 100 is also provided, and the housing assembly 100 may include the glass of the above embodiments. At least a portion of the housing assembly 100 is made of the above glass, so that the housing assembly 100 can have good blunt object impact resistance, bending crack resistance, and foreign object penetration resistance.

The specific shape, size, etc. of the case assembly 100 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 electronic device 200 applied thereto. It is understood that the housing assembly 100 may be partially formed of the glass described above, for example, the housing assembly 100 includes a bottom surface and at least one side surface connected to the bottom surface, in which case the bottom surface and the side surface may both be formed of the glass, or one of the bottom surface or the side surface may be formed of glass and the other may be formed of 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 200.

The present application also proposes an electronic device 200, and the electronic device 200 may include the case assembly 100 of the above embodiment. Thus, the electronic device 200 using the housing assembly 100 can have better blunt object impact resistance, bending crack resistance and foreign object penetration resistance.

Specifically, the specific type of the electronic device 200 is not particularly limited, and may be, for example, a mobile phone, a tablet computer, a wearable device, a game machine, various electric appliances for daily use, and the like, and the glass may be a battery cover of the electronic device 200 such as a mobile phone. In addition, it is understood that the electronic device 200 may include, in addition to the shell assembly 100, other structures and components necessary for conventional electronic devices, such as a mobile phone, a display module, a touch module, a memory, a motherboard, a fingerprint module, a camera module, a sound system, and so on.

Examples in the embodiments of the present application are described in detail below.

The glass substrate in the embodiment of the application can be made of Corning GG5 glass with the thickness of 0.55mm, and is subjected to strengthening treatment after the steps of cutting, grinding, primary polishing and the like.

The first strengthening can be carried out by using a first molten salt consisting of 38 percent of sodium nitrate and 62 percent of potassium nitrate, the treatment temperature is 380 ℃, and the strengthening time is 120 minutes.

The second strengthening can be carried out by a second molten salt consisting of 1-3% of sodium nitrate and 97-99% of potassium nitrate, the treatment temperature is 380 ℃, and the strengthening time is 20-25 minutes.

For the comparative data of the strengthening process parameters of the prior art and the scheme of the application, as shown in the following table 1, DOC represents the depth of the stress layer after the first strengthening, that is, the depth of the Na-Li exchange layer after the first strengthening, and DOL represents the depth of the K-Na exchange layer obtained by the second strengthening, that is, the inflection point stress depth.

TABLE 1

Prior Art	Range	This application	Range
				A ratio of strong ions	38％Na⁺,62％K⁺	A ratio of strong ions	38％Na⁺,62％K⁺
An intense temperature/time	380℃/120min	An intense temperature/time	380℃/125min
				CS	465～605MPa	CS	480～630MPa
CSK
		100～140MPa	CSK	80～145MPa
DOL					7.7～9.2um	DOL	7.8～9.4um
	DOC	100～115um	DOC	90～105um
CT					44～93MPa	CT	44～98MPa
	Ratio of two strong ions	9％Na⁺,91％K⁺	Ratio of two strong ions	1～3％Na⁺,99～97％K⁺
Second intense temperature/time					380℃/38min	Second intense temperature/time	380℃/25±5min
	CS	710～880MPa	CS	900～1250MPa
CSK					65～120MPa	CSK	50～120MPa
	DOL	8.2～10um	DOL	7.0～9.5um
DOC					100～115um	DOC	86～101um
	CT	44～95MPa	CT	44～100MPa

As can be seen from the above Table 1, in the first strengthening process, the strengthening time is increased by 5 minutes, and further the CS value of the glass is increased, the DOL value of the glass is increased, the CSK value of the glass is decreased, and the strength of the glass is primarily enhanced. In the second strengthening process, the proportion of sodium ions in the second molten salt is reduced, the proportion of potassium ions in the second molten salt is improved, the strengthening time of the second strengthening is shortened, the CS value of the glass is obviously improved, the DOL value is slightly reduced, the CSK value is basically kept stable, and the CT value is also basically kept stable. Therefore, it can be known that the surface compressive stress value (i.e. CS value) of the glass strengthened by the glass strengthening method of the present application is increased by about 200-.

Referring to table 2 below, table 2 shows a comparison of four-point bending strength of the glass strengthened by the strengthening parameters of the prior art and the strengthening parameters of the present application.

TABLE 2

Four point bending strength	Mean (average value)	Min (Min Zhong)	Max (maximum)
				Original enhancement parameters	650MPa	480MPa	800MPa
New enhanced parameters	850MPa	590MPa	1022MPa

As shown in the above tables 1 and 2, the glass strengthening method of the present application not only improves the surface compressive stress value (CS value) of the glass by 200-300MPa, but also improves the four-point bending strength (4PB) of the glass monomer by about 200 MPa.

In addition, referring to table 3 below, table 3 below shows the four corner mean fracture height of the glass obtained by combining the strengthening parameters of the present application with different polishing procedures through 32g and 110g ball drop experiments.

TABLE 3

From the above table 3, it can be known that, by adopting the enhanced parameters of the present application in combination with the polishing processes of fine polishing and back polishing, the crushing height of the four corners of the 32g falling ball is increased from 40-50cm to more than 60cm, and the crushing height of the four corners of the single falling ball is increased from the lowest 35cm to 55 cm. The crushing height of the four corners of the 110g falling ball is increased from 20cm to about 30 cm. And then the fine polishing procedure is added before the first strengthening and the re-polishing procedure is added after the second strengthening, so that the strength of the glass is greatly improved, and the strength performance of the glass is further enhanced.

Meanwhile, please refer to table 4 below, where table 4 shows comparison data of 110g ball drop experiments under three conditions of the existing strengthening parameters, the strengthening parameters of the present application, and the strengthening parameters of the present application plus the polishing process, the comparison data are respectively compared with 10 pieces of glass as experimental objects, and the data in the table indicates the number of broken pieces of glass at the corresponding height.

TABLE 4

As can be seen from table 4 above, the glass strengthened by the existing strengthening parameters is at risk of breaking when the height is less than 7cm, the glass strengthened by the strengthening parameters in the present application is broken when the height is 10cm, and further, the glass strengthened by the strengthening parameters in the present application and added with a new polishing process is broken when the height is 15 cm. The crushing height of the four corners of the 110g falling ball of the whole machine is increased to 15cm from the initial 7cm, and the strength of the glass is greatly improved after the strengthening parameters are used and the polishing process is added.

Referring to table 5 below, it can be seen that the strength of the glass can be improved by increasing the polishing process while strengthening under the strengthening parameters of the present application, and table 5 shows comparative data of the CS value, DOL, CSK value variation and 32g ball drop height at different back-polishing time.

TABLE 5

As can be seen from Table 5 above, the different back-polishing times have an effect on the compressive stress value (CS value) of the glass surface. The normal back polishing process is polyurethane finish polishing for 140s, the CS value is about 920MPa, the average strength of four corners of a 32g falling ball is more than 60cm, and the variation of other parameters is stabilized within a certain range. After the time of the re-polishing process is prolonged to 420s, the average CS value is about 840MPa, the average strength and the minimum strength of the four corners of the 32g falling ball are all larger than 70cm, and the strength is obviously improved; after the concave polishing time is increased to 490s, the CS is about 820MPa on average, and the average strength and the minimum strength of four corners of a 32g falling ball are more than 60 cm. As can be seen from the data, the polishing cost is increased due to too long polishing return time, the removal amount of the CS value of the glass is large, the falling ball strength is reduced, and therefore the polishing return process time can be set to be 140 +/-10 s so as to obtain a higher CS value and ensure that the value of the CSK is not too small.

In conclusion, the surface compressive stress value of the glass with the thickness of 0.5mm is improved by about 40% and the 4PB strength is improved by 25% by optimizing the strengthening process and the polishing process of the Corning GG5 material glass; by improving the polishing process after pressurization and the manufacturing process, the 32g ball drop strength of the glass is improved by more than 40 percent, and the problem of glass strength failure is effectively solved.

In the description herein, references to the description of the terms "one embodiment," "certain embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples" or the like mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present application. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

While embodiments of the present application have been shown and described, it will be understood by those of ordinary skill in the art that: numerous changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the application, the scope of which is defined by the claims and their equivalents.

Claims

1. A method of strengthening glass, comprising:

2. The glass strengthening method according to claim 1, wherein the glass substrate after the second strengthening has a surface compressive stress value of 900MPa to 1250 MPa.

3. The glass strengthening method according to claim 1, wherein a proportion of the first metal ions in the first molten salt is 38%, and a proportion of the second metal ions in the first molten salt is 62%.

4. The glass strengthening method of claim 1, wherein the second strengthening is performed for a time period ranging from 20 minutes to 30 minutes.

5. The glass strengthening method according to claim 1, wherein the glass substrate after the first strengthening has a central tensile stress of 44MPa to 98MPa, and the glass substrate after the second strengthening has a central tensile stress of 44MPa to 100 MPa.

6. The glass strengthening method according to claim 1, wherein after the step of performing the second strengthening on the glass substrate subjected to the first strengthening using the second molten salt, the glass strengthening method further comprises:

performing back polishing on the glass substrate subjected to secondary strengthening;

wherein the polishing time for the back polishing of the glass substrate is 130-150 seconds.

7. The glass strengthening method of claim 6, wherein the thickness of the glass substrate after the back-polishing is 0.46mm to 0.53 mm.

8. A glass produced by the glass strengthening method of any one of claims 1-7.

9. A housing assembly comprising the glass of claim 8.

10. An electronic device comprising the housing assembly of claim 9.