CN111825345A - Chemical strengthening method of glass, strengthened glass, application and display device - Google Patents
Chemical strengthening method of glass, strengthened glass, application and display device Download PDFInfo
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- CN111825345A CN111825345A CN202010628071.1A CN202010628071A CN111825345A CN 111825345 A CN111825345 A CN 111825345A CN 202010628071 A CN202010628071 A CN 202010628071A CN 111825345 A CN111825345 A CN 111825345A
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- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C21/00—Treatment of glass, not in the form of fibres or filaments, by diffusing ions or metals in the surface
- C03C21/001—Treatment of glass, not in the form of fibres or filaments, by diffusing ions or metals in the surface in liquid phase, e.g. molten salts, solutions
- C03C21/002—Treatment of glass, not in the form of fibres or filaments, by diffusing ions or metals in the surface in liquid phase, e.g. molten salts, solutions to perform ion-exchange between alkali ions
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- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C3/00—Glass compositions
- C03C3/04—Glass compositions containing silica
- C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
- C03C3/097—Glass compositions containing silica with 40% to 90% silica, by weight containing phosphorus, niobium or tantalum
Abstract
The invention relates to a chemical strengthening method of glass, strengthened glass, application and a display device. The method for strengthening the glass comprises the following steps: carrying out first chemical strengthening treatment on glass in first molten salt at the temperature of 360-440 ℃ for 2-6 h, wherein the mass percentage of sodium nitrate in the first molten salt is more than or equal to 20%; carrying out secondary chemical strengthening treatment on the glass in second molten salt at the temperature of 380-420 ℃ for 1-4 h, wherein the mass percentage of potassium nitrate in the second molten salt is more than or equal to 80%; annealing the glass at 260-300 ℃ for 1-4 h. The glass strengthened by the method has good mechanical impact resistance and high falling and breaking height, and can effectively avoid or reduce the condition that the screen or other cover glass is broken due to the fact that intelligent equipment such as a mobile phone falls down to the ground carelessly.
Description
Technical Field
The invention relates to the field of glass, in particular to a chemical strengthening method of glass, strengthened glass, application and a display device.
Background
Thin plate glass is used as a cover glass for protecting a liquid crystal screen of, for example, a mobile phone, a Personal Digital Assistant (PDA), a digital camera, a Flat Panel Display (FPD), or a cover glass for a housing of a mobile terminal device. In recent years, these mobile phones, PDAs, and the like have been becoming thinner and more highly functional, and have been required to have high mechanical strength. Therefore, tempered glass in which a thin glass substrate is chemically strengthened is used as the cover glass.
Such tempered glass is generally chemically strengthened by ion exchange treatment. The ion exchange treatment typically comprises: the glass is immersed in a molten salt containing potassium and/or sodium at a temperature of 350 to 550 ℃, whereby sodium ions and lithium ions on the surface of the glass are exchanged with potassium ions and/or sodium ions in the ion exchange salt, and a compressive stress layer is formed on the surface of the glass.
In the traditional technology, a one-step chemical strengthening method usually needs long-time chemical strengthening, so that the cost of chemical strengthening is increased, and ultrathin glass is easy to warp due to long-time strengthening treatment, so that the yield is reduced, and the preparation of chemical toughened glass with good comprehensive performance is difficult. And by adopting two-step or multi-step ion exchange process, the surface compressive stress value higher than 600MPa and the stress layer depth larger than 20 μm are difficult to be considered, so that when the glass is used as protective glass of an electronic product, the electronic product is difficult to be protected, and the screen or the cover plate is damaged when the electronic product falls down to the ground carelessly.
Disclosure of Invention
Therefore, there is a need for a chemical strengthening method for glass, which has good mechanical impact resistance and high drop height, and can effectively avoid or reduce the occurrence of screen or other cover glass fracture caused by the careless dropping of terminal equipment such as mobile phones.
In addition, there is a need to provide a strengthened glass, applications thereof, and display devices.
A chemical strengthening method of glass comprises the following steps:
carrying out first chemical strengthening treatment on glass in first molten salt at the temperature of 360-440 ℃ for 2-6 h, wherein the mass percentage of sodium nitrate in the first molten salt is more than or equal to 20%;
carrying out secondary chemical strengthening treatment on the glass subjected to the primary chemical strengthening treatment in second molten salt at the temperature of 380-420 ℃ for 1-4 h, wherein the mass percentage of potassium nitrate in the second molten salt is more than or equal to 80%; and
and annealing the glass subjected to the second chemical strengthening treatment at 260-300 ℃ for 1-4 h.
In one embodiment, after the step of annealing, the method further includes: and carrying out third chemical strengthening treatment on the annealed glass in third molten salt at the temperature of 360-390 ℃, wherein the mass percentage of potassium nitrate in the third molten salt is not less than 95%.
In one embodiment, the time of the third chemical strengthening treatment is 0.5h to 1.0 h.
In one embodiment, after the third chemical strengthening treatment step, the method further comprises the step of repeatedly and alternately performing annealing treatment and chemical strengthening treatment on the glass.
In one embodiment, the glass comprises, in mass percent: 55 to 65 percent of SiO213 to 30 percent of Al2O32 to 6 percent of Li2O, 6 to 11 percent of Na2O, 1 to 6 percent of K2O, 0 to 4 percent of MgO, 0 to 3 percent of ZnO and 0.1 to 3.0 percent of B2O30 to 3 percent of P2O5And 0.1 to 4.0% of ZrO2。
In one embodiment, the first molten salt contains sodium nitrate in an amount of 40% by mass or more.
In one embodiment, the stress layer depth of the glass after the first chemical strengthening treatment is more than 80 μm, and the stress value at the position of 30 μm is more than or equal to 90 MPa.
In one embodiment, the surface compressive stress value of the glass after the second chemical strengthening treatment is more than or equal to 650MPa, the stress value at the position of 30 microns is more than or equal to 80MPa, and the stress layer depth is more than or equal to 100 microns.
A tempered glass having a surface compressive stress value of at least 970MPa, a compressive stress value at 10 μm of at least 270MPa, a compressive stress value at 30 μm of at least 160MPa, a compressive stress value at 50 μm of at least 95MPa, and a depth of stress layer of at least 170 μm.
In one embodiment, the strengthened glass is prepared by the above-described method for chemically strengthening glass.
The application of the strengthened glass in preparing display devices or preparing bulletproof glass.
A display device comprises a cover plate, wherein the cover plate is obtained by processing the strengthened glass.
According to the chemical strengthening method of the glass, the glass after the first chemical strengthening treatment and the second chemical strengthening treatment is annealed for 1 h-4 h at 260-300 ℃, so that the defects of local nonuniformity, microcracks and the like caused by a sample in a natural cooling process are reduced, the mechanical strength of the glass is improved, and the treated glass has a higher surface stress value and a deeper stress layer depth and has a gradient stress value by adjusting the temperature, molten salt proportion, time and other parameters in each chemical strengthening treatment and annealing treatment, so that when the glass is used as protective glass, the glass has good mechanical impact resistance and high falling and breaking height, and the condition that a screen or other cover glass is broken due to the fact that intelligent equipment such as a mobile phone falls to the ground carelessly can be avoided or reduced.
Drawings
FIG. 1 is a process flow diagram of a method for chemically strengthening glass in accordance with one embodiment.
Detailed Description
In order that the invention may be more fully understood, reference will now be made to the following description taken in conjunction with the accompanying drawings. The detailed description sets forth the preferred embodiments of the invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
Referring to fig. 1, a chemical strengthening method for glass according to an embodiment includes the following steps:
step S110: carrying out first chemical strengthening treatment on the glass in first molten salt at the temperature of 360-440 ℃ for 2-6 h, wherein the mass percentage of sodium nitrate in the first molten salt is more than or equal to 20%.
Specifically, the glass used in step S110 is a lithium aluminosilicate glass. The glass has a glass transition temperature of less than 590 ℃.
In this embodiment, the glass comprises, in mass percent: 55 to 65 percent of SiO213 to 30 percent of Al2O32 to 6 percent of Li2O, 6 to 11 percent of Na2O, 1 to 6 percent of K2O, 0 to 4 percent of MgO, 0 to 3 percent of ZnO and 0.1 to 3.0 percent of B2O30 to 3 percent of P2O5And 0.1 to 4.0% of ZrO2。
Further, in one of the embodiments, SiO2The mass percentage of the component (A) is 58-63%.
In one embodiment, Al2O3The mass percentage of the component (A) is 16-24%. Further, Al2O3The mass percentage of the component (A) is 19-22%.
By Li in the above glass+With Na in the molten salt+Ion exchange is carried out, the depth of a surface compressive stress layer can be improved in a short time, and the glass has better qualityDifferent mechanical impact resistance. When Li is present2When the mass percentage of O is less than 2%, the aluminosilicate glass is difficult to obtain higher surface compressive stress depth of layer; when Li is present2When the mass percentage of O is higher than 6%, the manufacturing cost is increased, the glass expansion coefficient is remarkably increased, the glass crystallization tendency is too high, and the probability of generating stone defects is remarkably increased. In one of the embodiments, Li2The mass percentage of O is 3.0-5.5%.
When Na is present2When the mass percentage of O is less than 6%, the melting performance of the aluminosilicate glass is deteriorated, and the stress value of a K-Na ion exchange layer formed by the strengthened aluminosilicate glass is small, the depth is shallow, the CS value of a shallow surface layer is low, the microhardness is poor, cracks are generated, and the falling resistance of corresponding products is reduced. When Na is present2When the mass percentage of O is higher than 11%, the aluminosilicate glass has a poor network structure, the stability of mechanical properties and thermal properties is reduced, and the chemical durability is poor. Further, Na2The mass percentage of O is 7-10%.
When K is2When the mass percentage of O is less than 1%, the stress depth of a K-Na ion exchange layer formed by the chemically strengthened aluminosilicate glass is shallow, which is not favorable for K in the ion exchange process+Ions migrate to the inner layer. When K is2When the content of O is more than 6% by mass, the network structure of the aluminosilicate glass is deteriorated, the stability of the thermal properties is lowered, and the weather resistance is deteriorated. Further, K2The mass percentage of O is 2.5-4%.
The zirconia can improve the chemical stability and ion exchange performance of the aluminosilicate glass, increase the surface hardness of the aluminosilicate glass, and also can improve the pressure required by the aluminosilicate glass to form cracks, so that the aluminosilicate glass is more scratch-resistant and more drop-resistant. Only a small amount of ZrO is required2Can meet the requirements, and ZrO2Too much will significantly increase the melting temperature of the aluminosilicate glass and cause defects such as stones. Thus, ZrO2The mass percentage content of the components is 0.1-4.0%.
In one embodiment, the glass is prepared as follows: weighing the raw materials according to mass percent, fully mixing the glass raw materials uniformly, melting the glass raw materials for 8 hours at 1650 ℃ by using a platinum crucible, stirring by using a platinum stirring paddle, cooling to 1500 ℃ after the stirring paddle is drawn out, preserving heat for 1 hour for homogenization, casting the mixture onto an iron mold preheated to 450 ℃ to form glass blocks of about 80mm multiplied by 160mm, immediately transferring the glass blocks to an annealing furnace after hardening, annealing at 700 ℃, preserving heat for 2 hours, cooling to 140 ℃ for 6 hours, and naturally cooling. Then the large sample is processed into a double-sided polished glass sheet with the thickness of 70mm multiplied by 140mm multiplied by 0.7mm by a cold working cutting grinding polishing process for standby.
It should be noted that the above description only shows one process for preparing glass, but the process for preparing glass is not limited to the above process, and other methods commonly used in the art may be used.
Specifically, the temperature of the first molten salt is 360 ℃, 380 ℃, 400 ℃, 420 ℃ or 440 ℃. The temperature of the first molten salt is lower than 360 ℃, the melting effect of the mixed salt is poor, phase separation and incomplete mixing can occur, and toughened salt liquid is changed from a clear and transparent complete mixing state to a turbid partial mixing state, so that instability of glass toughening is caused, and serious quality defects are caused. The temperature of the first molten salt is increased to increase the deep stress value and then is gradually reduced along with the stress relaxation phenomenon of the thermal effect, so that the temperature is not more than 440 ℃, and the glass is bent and deformed to be scrapped in the toughening process due to the excessively high temperature.
The time of the first chemical strengthening treatment is 2h, 3h, 4h, 5h or 6 h. The chemical strengthening treatment time is short, and a deep stress layer depth and a large deep layer stress value are difficult to obtain, so that the strength of the glass cannot be effectively enhanced. The chemical toughening time is more than 6 hours, which can seriously restrict the production and reduce the production efficiency, and the chemical toughening agent is not recommended to be used in the actual production.
Specifically, the first molten salt includes sodium nitrate and potassium nitrate. The mass percentage content of the sodium nitrate in the first molten salt is 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or 100%. Further, the mass percentage content of sodium nitrate in the first molten salt is more than or equal to 40%. When the mass percentage of sodium nitrate in the first molten salt is low, the depth of the stress layer is low due to less sodium ions available for exchange in the molten salt, and the stress value of the deep stress layer is almost 0.
In the first chemical strengthening treatment process, Li in the glass is passed+With Na in the molten salt+Ion exchange is carried out, a compressive stress layer can be obtained within a limited time, and the depth of the compressive stress layer is deeper, so that the glass has more excellent mechanical impact resistance; then, a second chemical strengthening treatment process is carried out, and Na in the stress layer of the glass shallow surface layer is used+With K in the molten salt+The ion exchange is carried out, so that a higher compressive stress value can be obtained in a shorter time, and the glass has more excellent scratch resistance and microhardness.
In addition, the ion exchange speed of the pure potassium nitrate molten salt and the glass is too high, so that a large amount of potassium ions (K) are generated+) In a short time into the glass, these K+And the glass is accumulated on the superficial layer of the glass, is not easy to further migrate inwards, and simultaneously blocks a channel for the ions to enter, so that the ion exchange cannot be carried out continuously. Therefore, the pure potassium nitrate molten salt is not easy to obtain good ion exchange effect. Thus, in a chemical strengthening process involving two-step or multi-step ion exchange, potassium nitrate (KNO) is used3) With sodium nitrate (NaNO)3) By adding NaNO3To adjust the ion exchange rate.
After the glass is subjected to primary chemical strengthening treatment, the depth of the compressive stress layer is more than 80 μm. The depth of the compressive stress layer is more than 80 mu m, so that the molten salt with high potassium content can be subjected to secondary chemical strengthening treatment or third chemical treatment to obtain the depth requirement of more than 100 mu m, and the falling-resistant effect of harsher rough ground can be realized.
The compressive stress value (CS30) of 30 μm after the glass is subjected to the first chemical strengthening treatment is more than or equal to 90 MPa. When glass falls from the eminence, contact grit or concrete ground, the coarse grain that has different particle diameters can be embedded into the glass surface to cause destruction to glass, through glass counter weight test abrasive paper fall performance, discover to daily contactThe obtained sand and stone particles are mainly 60 meshes to 180 meshes, and simulation tests show that the compressive stress value and the anti-drop effect of the glass in the stress depth of 30-50 mu m in the deep range have positive correlation, so that the CS30 of the glass needs to be more than or equal to 90MPa to effectively enhance the anti-drop strength of the glass during the first chemical strengthening treatment, and the ion exchange in the depth range mainly adopts Na-Li exchange, so that the first molten salt contains higher NaNO3Proportioning and longer exchange time may be beneficial to increase the deep layer compressive stress value.
Step S120: and carrying out secondary chemical strengthening treatment on the glass in second molten salt at the temperature of 380-420 ℃ for 1-4 h, wherein the mass percentage of potassium nitrate in the second molten salt is more than or equal to 80%.
Specifically, the temperature of the second molten salt is 380 ℃, 390 ℃, 400 ℃, 410 ℃ or 420 ℃. The time of the second chemical strengthening treatment is 1h, 2h, 3h or 4 h. The higher temperature or longer time of the second chemical strengthening treatment can cause the structure of the compressive stress layer on the surface to be relaxed, and the compressive stress value of the surface is reduced. The temperature of the second chemical strengthening treatment is low or the time is short, the surface layer compressive stress value is very shallow, and the purpose of strengthening the glass strength cannot be achieved.
The mass percentage of the potassium nitrate in the second molten salt is 80%, 85%, 90%, 95% or 100%. In step S110, the first molten salt having a high sodium nitrate content imparts a greater depth of compressive stress and a deeper compressive stress to the glass, but weakens the surface compressive stress value, and therefore in order to sufficiently increase the glass tempering strength, tempering of the high potassium molten salt is continued in step S110 to impart a higher compressive stress value to the glass surface. The lower content of potassium nitrate causes that the exchange of sodium ions and potassium ions on the surface of the glass can not be fully carried out, and the compressive stress value of the surface is reduced.
By carrying out the second chemical strengthening treatment on the glass, the surface compressive stress value (CS0) of the glass is more than or equal to 650MPa, the CS30 is more than or equal to 80MPa, and the depth of the compressive stress layer is more than or equal to 100 mu m.
Step S130: annealing the glass at 260-300 ℃ for 1-4 h.
In the traditional process, the glass after chemical strengthening treatment can be used after natural cooling. However, the inventor finds that the conventional natural cooling causes the compressive stress of the sample after the tempering to be in a short-time solidification process, so that the glass sample has local non-uniformity, micro-cracks and local defects in the manufacturing process, and the local stress abnormality in the glass tempering process can be caused. Therefore, in the present embodiment, the glass is annealed for a long time after the chemical strengthening treatment, so that the difference between the local regions and the whole glass is reduced, the tensile stress at the center of the glass is reduced, the risk of spontaneous explosion is reduced, the whole mechanical strength of the glass is improved, and the risk of glass breakage is reduced. However, since annealing is accompanied by a certain stress relaxation, a third chemical strengthening treatment may be performed for an extremely short time after the annealing treatment in a case or standard where a relatively high demand is imposed.
Specifically, the temperature of the annealing treatment is 260 ℃, 270 ℃, 280 ℃, 290 ℃ or 300 ℃. The time of the annealing treatment is 1h, 2h, 3h or 4 h. The annealing treatment temperature is too low, no effect is produced, the temperature is too high, the stress relaxation is serious, and the tempering removing effect is obvious. The annealing time is too short, the effect is not significant, the annealing time is too long, and the strength of the glass is partially reduced. The tempering at the low temperature of 260-300 ℃ for a short time of 1-4 hours is beneficial to improving the stability of the glass strength, thereby improving the average level of four-point bending and ball falling height of the glass and also improving the median level of 60-mesh and 180-mesh sand paper falling.
Step S140: and carrying out third chemical strengthening treatment on the annealed glass in third molten salt at the temperature of 360-390 ℃ for 0.5-1.0 h, wherein the mass percentage of potassium nitrate in the third molten salt is more than or equal to 95%.
Specifically, the temperature of the third molten salt is 360 ℃, 370 ℃, 380 ℃ or 390 ℃. The temperature of the third molten salt is too high, so that the stress relaxation of the internal deep compressive stress is caused, and the mechanical property and the anti-falling capability of the rough ground are reduced. The time of the third chemical strengthening treatment is 0.5h or 1 h. The time of the third chemical strengthening treatment is too short, the mechanical property and the rough-ground-resistant falling capacity are not changed greatly, the time is too long, and the internal deep layer pressure stress is loosened to a certain extent, so that the mechanical property and the rough-ground-resistant falling capacity are reduced.
Specifically, the third molten salt includes potassium nitrate and sodium nitrate. In one embodiment, the potassium nitrate in the third molten salt is 95%, 96%, 97%, 98%, 99% or 100% by mass. The mass percentage of the potassium nitrate is too low, so that the compressive stress on the surface of the glass is rapidly reduced, the mechanical property is reduced, and the drop resistance of the rough ground is reduced.
The low-temperature short-time tempering in step S140 can rapidly increase the compressive stress value of the surface without causing the deep-lamination stress relaxation phenomenon, thereby simultaneously improving the mechanical properties and the anti-falling capability of the rough ground.
After the third chemical strengthening treatment step, the annealing and chemical strengthening treatment steps may be alternately repeated for the glass to further improve the strength of the glass. In one embodiment, after step S140, the method further includes repeating steps S130 and S140 in sequence to perform an annealing treatment and a fourth chemical strengthening treatment on the glass.
The glass treated in the steps S110 to S140 has a surface compressive stress value CS0 of at least 970MPa, a compressive stress value CS10 of at least 270MPa at a position of 10 mu m, a compressive stress value CS30 of at least 160MPa at a position of 30 mu m, a compressive stress value CS50 of at least 95MPa at a position of 50 mu m, and has gradient stress strength. And has a large depth of compressive stress layer of at least 170 μm. Experiments prove that the four-point bending strength of the glass after the treatment is at least 880MPa, the ball falling height of a 64g steel ball is at least 120cm, the median of the falling height of 180-mesh sand paper is at least 140cm, and the median of the falling height of 60-mesh sand paper is 90 cm. Therefore, the glass after being treated has excellent mechanical property and rough ground resistance and drop resistance, can be used as protective glass of electronic equipment, and can avoid or reduce the condition that a screen or other cover glass is broken due to the fact that intelligent equipment such as a mobile phone drops on the ground carelessly.
The traditional glass cover plate market mainly takes (boron) aluminum silicon glass and lithium (boron) aluminum silicon glass as main materials, and P is added into individual products2O5The most important advantage of the compositions, such as Gorilla glass from corning, T2X-1 from NEG, Dragon glass from Asahi glass, panda glass from Asahi rainbow and KK3 glass from south glass in China, is the ability to perform rapid chemical tempering.
The composition range of the traditional high-alumina glass is roughly as follows: 55 to 70 percent of SiO by mass percentage212 to 23 percent of Al2O313 to 18 percent of Na2O, 0 to 5 percent of K2O, 2 to 6 percent of MgO and 0 to 5 percent of B2O30 to 2% of ZrO2. Because of high content of alumina, the strength of the glass is higher than that of common soda-lime glass, and the ion exchange capacity of the glass is stronger, so that the glass is mainly applied to protective cover plates, protective paster glass and the like of electronic products and has higher visible light transmittance. One conventional method may be to subject the high alumina glass to an ion exchange bath at a temperature in the range of about 320 ℃ to about 450 ℃, for a submersion time that may vary from about 15 minutes to about 16 hours, and with a maximum compressive stress of at least about 400MPa, 800MPa, 930MPa, or 1050MPa, and a compressive stress layer with a depth of layer (in samples having a thickness of 1 mm) of at least about 40 μm. The condition of falling by accident can be effectively coped with. In another conventional method, high alumina glass is subjected to pure KNO at 410 DEG C3Ion exchange is carried out in the bath for 8 hours, achieving a compressive stress of at least 950MPa at the surface thereof and a depth of layer of at least about 40 μm in the compressive stress layer.
If the ion exchange time is prolonged to more than 480min in the method, the depth of the stress layer can be increased to be about 50 μm, but the surface compressive stress value is correspondingly reduced, and an alkali-rich layer which is difficult to remove is easily formed on the surface of the strengthened glass, so that a microcrack defect is formed, and the overall strength of the protective cover plate is seriously influenced. The one-step ion exchange chemical strengthening process greatly increases the processing cost of glass cover plate manufacturers, and the ultrathin glass is easy to warp and has low yield after being strengthened for a long time. The purity of the potassium nitrate salt is improved, so that the performances of surface stress, stress layer depth, bending strength and the like of the glass after chemical toughening can be effectively improved. However, the use of high-purity potassium nitrate salt increases the cost of chemical tempering, and the chemical tempered glass with better comprehensive performance is difficult to prepare.
In view of the bottleneck of improving the performance of the glass by the one-step ion exchange chemical strengthening process, a certain amount of Li is introduced into the glass composition in part of technical schemes2And O, carrying out an ion exchange chemical strengthening process of a two-step method or a multi-step method, respectively finishing the ion exchange of Li-Na and Na-K by controlling the difference of the molten salt concentration of the first step and the second step, and simultaneously obtaining higher compressive stress layer depth and ideal surface compressive stress value, thereby improving the falling and breaking height of the glass cover plate and obtaining the protective glass with more excellent mechanical property and mechanical impact resistance.
In the presence of NaNO3And KNO3Is subjected to chemical strengthening in a single or multiple ion exchange baths for a short period of time (2 hours to 4 hours) to form a deep stress layer depth. Compressive stresses of at least about 700MPa, alternatively at least about 800MPa, alternatively at least about 900MPa, can be achieved using either a one-step ion exchange process or a two-step ion exchange process. In some cases, DOl is at least 70 μm; in other cases, the depth of the compressive stress layer is at least about 100 μm.
In another method, the glass is subjected to pure KNO3After medium tempering, a potassium ion stress layer can be formed, Dol is at least 20 mu m, and CS0 is at least 600 MPa. At KNO3And NaNO3In mixed salts or with KNO3And NaNO3Two-step tempering is carried out, so that potassium and sodium ion stress layers can be formed simultaneously, Dol0 is at least 50 mu m, and CS0 is at least 600 MPa.
CS generally above 600MPa and Dol0 above 100 μm and glasses with glass transition temperatures below 590 ℃ are of interest. However, the glass treated by the method is difficult to simultaneously consider high surface compressive stress value, deep compressive stress layer depth and lower glass transition temperature, so that the mechanical properties (such as four-point bending property and ball falling property) and the anti-falling capability of rough ground of the glass are lower, and the situation that the screen or other cover plate glass of intelligent equipment such as a mobile phone is broken due to the fact that the intelligent equipment falls down to the ground carelessly cannot be effectively avoided or reduced.
The chemical strengthening method for glass of the present embodiment has at least the following advantages:
(1) according to the chemical strengthening method of the glass, the glass is sequentially subjected to the first chemical strengthening treatment, the second chemical strengthening treatment, the annealing treatment and the third chemical strengthening treatment, and parameters such as temperature, molten salt proportion and time in each chemical strengthening treatment are adjusted, so that the treated glass has a high surface stress value and a deep stress layer depth and has a gradient stress value, the treated glass can be used as protective glass of electronic equipment, and the situation that a screen or other cover glass is cracked due to the fact that intelligent equipment such as a mobile phone falls down to the ground carelessly is avoided or reduced.
(2) The chemical strengthening method of the glass has simple process, does not increase the process difficulty and is easy for industrial production.
The present invention also provides an embodiment of a strengthened glass having a surface compressive stress value CS0 of at least 970MPa, a compressive stress value CS10 at 10 μm of at least 270MPa, a compressive stress value CS30 at 30 μm of at least 160MPa, a compressive stress value CS50 at 50 μm of at least 95MPa, and a gradient stress strength. And has a large depth of compressive stress layer of at least 170 μm. Experiments prove that the four-point bending strength of the glass after the treatment is at least 880MPa, the ball falling height of a 64g steel ball is at least 120cm, the median of the falling height of 180-mesh sand paper is at least 140cm, and the median of the falling height of 60-mesh sand paper is 90 cm. Therefore, the glass after being treated has excellent mechanical property and rough ground resistance and drop resistance, can be used as protective glass of electronic equipment, and can avoid or reduce the condition that a screen or other cover glass is broken due to the fact that intelligent equipment such as a mobile phone drops on the ground carelessly.
In one embodiment, the strengthened glass is obtained by treating the glass according to the above embodiment by a chemical strengthening method.
In addition, the invention also provides application of the tempered glass in preparing a display device or preparing bulletproof glass. The strengthened glass has excellent mechanical property and rough ground resistance and drop resistance, can be used for protecting display devices, and can be prepared into bulletproof glass for automobiles, high-speed rails or motor cars.
An embodiment of the present invention also provides a display device including a cover plate obtained by the tempered glass processing of the above embodiment. In one embodiment, the display device is a mobile phone, a tablet, a computer, or the like.
The following are specific examples:
the compositions of the glasses used in examples 1 to 45 were specifically: 61% by mass of SiO219.5% of Al2O35% of Li2O, 9% of Na2O, 1% of K2O, 1% MgO, 0.5% ZnO, 1% B2O30.5% of P2O5And 1.5% of ZrO2。
The preparation process of the glass comprises the following specific steps: weighing the raw materials according to mass percent, fully mixing the glass raw materials uniformly, melting the glass raw materials for 8 hours at 1650 ℃ by using a platinum crucible, stirring by using a platinum stirring paddle, cooling to 1500 ℃ after the stirring paddle is drawn out, preserving heat for 1 hour for homogenization, casting the mixture onto an iron mold preheated to 450 ℃ to form glass blocks of about 80mm multiplied by 160mm, immediately transferring the glass blocks to an annealing furnace after hardening, annealing at 700 ℃, preserving heat for 2 hours, cooling to 140 ℃ for 6 hours, and naturally cooling. Then the large sample is processed into a double-sided polished glass sheet with the thickness of 70mm multiplied by 140mm multiplied by 0.7mm by a cold working cutting grinding polishing process for standby.
Examples 1 to 11
The specific procedure of the first chemical strengthening treatment of the glasses of examples 1 to 11 is as follows:
sodium nitrate and potassium nitrate were mixed in the proportions (mass percentages) of sodium nitrate and potassium nitrate shown in table 1 in examples 1 to 11 to prepare a first molten salt. The polished glass sheets were immersed in the first molten salt of examples 1 to 11 at 400 ℃ for 4 hours, respectively, to thereby effect sufficient chemical ion exchange between alkali metal ions in the glass and alkali metal ions in the molten salt, and ions having a large radius were exchanged for ions having a small radius, thereby generating a squeezing action to generate a compressive stress, and increasing the strength of the glass. Of these, examples 10 and 11 are comparative examples. Measuring the surface compressive stress value CS0, the compressive stress value CS10 with the depth of 10 mu m, the compressive stress value CS30 with the depth of 30 mu m, the compressive stress value CS50 with the depth of 50 mu m and the compressive stress value CS100 with the depth of 100 mu m after the first chemical treatment by a stress tester FSM6000UV and SLP1000 of the Japanese origin; the maximum compressive layer depth Dol0 for the compressive stress values is reported in table 1.
TABLE 1 first chemical strengthening treatment and associated Performance data
The glass is tempered for 4 hours at 400 ℃ by molten salt with different proportions, and NaNO can be found in the tempered glass3When the mass percentage is higher than 40%, as in examples 1 to 7, the ion exchange between the glass and the first molten salt is mainly Li-Na, and a small amount of Na-K and Li-K exchange is carried out, so that a low stress layer can be formed on the surface layer of the glass, whereas a compressive stress layer higher than 150MPa is formed at a depth of more than 30 μm, and NaNO is used as the compressive stress layer3When the content is between 20% and 40%, as in examples 8 to 9, the first molten salt contains less exchangeable Na ions, and the kinetic conditions of ion permeation exchange are insufficient, so that the tempering depth is further reduced, which is slightly larger than 100 μm, and exchangeable Na — Li exchange at a depth of 30 μm or more is reduced, and the stress value at a depth of more than 30 μm is further reduced to 90MPa, but the Na ions formed by exchange and Na ions contained in the original glass component are exchanged with K ions rich in the tempered molten salt, so that a high pressure stress layer can be formed within a depth of 10 μm of the shallow surface layer of the glass. With NaNO in the first molten salt3The content of (b) is further reduced to 20% by mass or less, and as in examples 10 to 11, the depth of the compressive stress is rapidly reduced to 80 μm or less, and the value of the compressive stress in the deep layer stress layer is also rapidly reduced to 0. Therefore, in the first chemical strengthening treatment process, the NaNO in the first molten salt is comprehensively considered and combined with the influence of the tempering stress curve on the strength of the glass3Is not less than 20 percent by mass, and nitric acid is more preferableThe mass percentage of the sodium is more than or equal to 40 percent.
The first chemical strengthening treatment of examples 12 to 19 is specifically performed as follows:
further investigating the influence of temperature and time on the first chemical strengthening treatment, examples 12 and 13 were carried out by performing chemical strengthening treatment at 360 ℃, 2 hours and chemical strengthening treatment at 440 ℃, 6 hours, respectively, on the toughening salt ratio of example 1; in examples 14 and 15, the chemical tempering treatment was performed at 360 ℃ for 2 hours and at 440 ℃ for 6 hours, respectively, on the tempering salt composition of example 9; examples 16 and 17 were conducted by chemical tempering treatment at 360 deg.C for 1 hour and chemical tempering treatment at 460 deg.C for 6 hours, respectively, on the tempering salt formulation of example 1; in example 18 and example 19, the chemical tempering treatment was performed at 360 deg.C for 1 hour and at 460 deg.C for 6 hours, respectively, on the tempering salt formulation of example 9. Of these, examples 16 to 19 are comparative examples. In addition, because the chemical toughening time is more than 6 hours, the production can be seriously restricted, the production efficiency is reduced, the use is not recommended, the temperature is lower than 360 ℃, the melting effect of mixed salt is poor, phase separation and incomplete mixing can occur, the toughened salt solution is changed from a clear and transparent complete mutual dissolving state to a turbid partial mixing state, the instability of glass toughening is caused, and serious quality defects are caused. The glasses treated in examples 12 to 19 were tested for CS0, CS10, CS30, CS50, CS100 and Dol0 in the same manner as in examples 1 to 11, as shown in table 2.
Table 2 process conditions and associated performance data for the first chemical treatment
In order to obtain a sufficient compressive stress depth and a large value of the deep compressive stress, the first step of the compressive stress depth Dol0 must be greater than 80 μm in order to pass through the second or third step of the high potassium contentThe molten salt can bear the drop-resistant effect of harsher rough ground only by obtaining the depth requirement of more than 100 mu m, but the examples 16 and 18 can not meet the basic requirement at all, and the compressive stress value at the compressive stress depth of a deeper range of 30 mu m to 50 mu m is smaller, so the requirement of effectively enhancing the glass strength can not be met. In addition, the compressive stress value of the glass in the compressive stress depth of 30-50 microns in the deep range has positive correlation with the anti-falling effect, so that the CS30 of the glass needs to be more than or equal to 90MPa to effectively enhance the anti-falling strength of the glass during tempering, and the ion exchange in the deep range is mainly Na-Li exchange, so that high NaNO is provided3The molten salt ratio and the longer exchange time can be beneficial to increasing the value of the deep compressive stress, the higher temperature can firstly increase the value of the deep compressive stress and then gradually decrease along with the stress relaxation phenomenon of the thermal effect, so the temperature is not suitable to exceed 440 ℃, and the excessively high temperature can also cause the glass to be bent and deformed during the toughening process and be discarded, as in example 17 and example 19. Therefore, in the first chemical strengthening treatment, the toughening temperature is preferably 360 ℃ to 440 ℃, and the toughening time is preferably 2 hours to 6 hours.
Through the analysis of the results of the first chemical strengthening treatment, we found that NaNO was present3The first molten salt with high content endows the glass with larger compressive stress depth and deep compressive stress, but weakens the surface compressive stress value, so in order to fully increase the glass toughening strength, the toughening of the high-potassium molten salt is carried out on the basis of the first chemical strengthening treatment, the higher compressive stress value is endowed to the glass surface, and the toughening time and temperature of the second chemical strengthening treatment are strictly controlled, so as to avoid the stress relaxation phenomenon of the toughened layer after the first chemical strengthening treatment.
The second chemical strengthening treatment of examples 20 to 28 was carried out as follows:
the glasses subjected to the first chemical strengthening treatment of example 1 and example 9 were subjected to a second chemical strengthening treatment with a second molten salt in the following table 3, respectively. Wherein, in the embodiment 20 to the embodiment 22, the embodiment 1 is respectively tempered at 400 ℃ for 3 hours and 380 ℃ for 1 hour, andtempering for 4 hours at 420 ℃; examples 23 to 24 are examples 9 in which the steel was tempered at 380 ℃ for 1 hour and at 420 ℃ for 4 hours, respectively; example 25 is 70% by mass KNO of example 13The second molten salt is tempered at 360 ℃ for 1 hour; example 26 is KNO in an amount of 80% by mass in example 13The second molten salt is tempered at 440 ℃ for 6 hours; example 27 is example 1 with 100% KNO3The molten salt is tempered for 0.5 hour at 360 ℃; example 28 is 90% by mass KNO of example 93The molten salt was tempered at 440 ℃ for 0.5 hour, see Table 3. Among them, examples 25 to 28 are comparative examples. Similarly, in the second chemical strengthening treatment, if the chemical toughening time exceeds 6 hours, the production is severely restricted, the production efficiency is reduced, the use is not recommended, and the temperature is lower than 360 ℃, the melting effect of the mixed salt is poor, phase separation and incomplete mixing can occur, the toughened salt solution is changed from a clear and transparent complete mixing state to a turbid partial mixing state, the glass toughening is unstable, and serious quality defects are caused. The glasses after the second chemical strengthening treatment were tested for CS0, CS10, CS30, CS50, CS100 and Dol0 in the same manner as in examples 1 to 11. The four-point bending strength of the glass subjected to the second chemical strengthening treatment is tested by adopting a UH6203W glass static pressure tester of a constant-handling instrument, the ball falling height of 64g of steel balls of the glass subjected to the second chemical strengthening treatment is tested by adopting an LQ-50 ball falling impact tester of a Seikn instrument, and the falling height median of 180-mesh sand paper and the falling height median of 60-mesh sand paper of the glass subjected to the second chemical strengthening treatment are tested by adopting GP-2112-1 directional falling equipment of Shenzhen high-quality testing equipment and combining eagle-brand silicon carbide sand paper with different mesh numbers, so that the data shown in the following table 3 are obtained.
TABLE 3 Process conditions and associated Performance data for the second chemical strengthening treatment of the glass
Remarking: in example 27, the tempering time and the temperature are both low, so that the high stress layer is shallow, and cannot be detected by the existing FSM equipment and the like.
As can be seen from examples 20 to 24 in Table 3, the four-point bending strength, the ball drop bearing height and the drop resistance test of 60-180 mesh sandpaper ground can be obviously enhanced by higher surface compressive stress value and higher compressive stress depth of the glass, wherein CS0 is preferably larger than or equal to 650MPa, CS30 is preferably larger than or equal to 80MPa, and the stress layer depth Dol0 is preferably larger than or equal to 100 μm. Example 25 due to the lower KNO in the second molten salt3The content of the Na-K is not sufficient, so that the surface compressive stress value CS0 is reduced; in example 26, due to the higher tempering temperature and the longer tempering time, the structure of the compressive stress layer on the surface is relaxed, and the surface stress value is reduced; in example 27, the tempering time is only 0.5 hour, so that the surface layer has a very shallow high stress value, and the purpose of effectively enhancing the strength of the glass cannot be achieved; in example 28, the compressive stress layer on the surface is structurally relaxed due to the higher tempering temperature, so that the surface compressive stress value is reduced. Thus, in practice, KNO in the second molten salt is used in the second chemical treatment3The mass percentage content of the toughening agent is more than or equal to 80 percent, the toughening temperature is preferably 380 to 420 ℃, and the toughening time is preferably 1 to 4 hours.
The annealing process of examples 29 to 36 is specifically as follows:
after the glass subjected to the two-time chemical strengthening treatment is subjected to the annealing process shown in table 4, the glass is subjected to certain degree of glass body stress relaxation and structure adjustment so as to be convenient for the third high-potassium rigidized salt tempering. In example 29, the glass treated in example 22 was annealed at 300 ℃ for 1 hour; example 30 is to the example 22 after the treatment of glass for 300 degrees C, 4 hours annealing treatment; example 31 is to make example 22 after the treatment of glass 260 degrees C, 1 hours of annealing treatment; example 32 is the glass after example 22 was annealed at 260 ℃ for 4 hours; example 33 is to the example 22 after the treatment of glass for 320 degrees C, 4 hours of annealing treatment; example 34 is the embodiment 22 after the glass annealing treatment at 240 degrees C for 4 hours; example 35 is the embodiment 22 after the glass annealing treatment at 300 degrees C for 6 hours; in example 36, the glass treated in example 22 was annealed at 260 ℃ for 0.5 hour. Among them, examples 33 to 36 are comparative examples. The annealed CS0, CS10, CS30, CS50, CS100 and Dol0 were tested in the same manner as in examples 1 to 11. The annealed glass was tested for four-point bending strength, drop height of 64g steel balls, median drop height of 180-mesh sandpaper, and median drop height of 60-mesh sandpaper in the same manner as in examples 20 to 28, and data shown in Table 4 below were obtained.
TABLE 4 Process conditions and associated Performance data for glass annealing treatment
As can be seen from table 4, the annealing treatment of examples 29 to 32 at a low temperature of 260 to 300 ℃ for a short time of 1 to 4 hours is beneficial to improving the stability of the glass strength, so that the four-point bending strength and the average level of the ball drop height of the glass are improved, and the median level of the 60-mesh sand paper and the 180-mesh sand paper drop can also be improved; the annealing time was less than 1 hour, as in example 36 and the annealing temperature was 240 ℃, and as in example 34, the properties of the annealed glass did not change. Examples 33 and 35 partially degraded the performance of the annealed glass due to the higher annealing temperature and longer annealing time. Therefore, the annealing temperature is preferably 260 to 300 ℃ and the annealing time is preferably 1 to 4 hours.
The third chemical strengthening treatment of the glasses of examples 37 to 45 was carried out as follows:
the tempered glass after annealing treatment is tempered in a third molten salt with high potassium content or nearly pure potassium content at a low temperature for a short time, so that the compressive stress value of the surface can be rapidly increased without causing deep stress relaxation, and specific data are shown in table 5. In example 37, the glass treated in example 29 was immersed in a third molten salt containing 95 mass% potassium nitrate, and tempered at 390 ℃ for 0.5 hour; example 38 the glass treated in example 29 was immersed in a third molten salt containing 100% by mass of potassium nitrate and tempered at 380 ℃ for 1 hour; example 39 the glass treated in example 32 was immersed in a third molten salt containing 100% by mass of potassium nitrate and tempered at 370 ℃ for 0.5 hour; example 40 the glass treated in example 32 was immersed in a third molten salt containing 95% by mass of potassium nitrate and tempered at 360 ℃ for 1 hour; example 41 the glass treated in example 30 was immersed in a third molten salt containing 95% by mass of potassium nitrate and tempered at 380 ℃ for 1 hour; example 42 the glass treated in example 29 was immersed in a third molten salt containing 90% by mass of potassium nitrate and tempered at 380 ℃ for 1 hour; example 43 the glass treated in example 29 was immersed in a third molten salt containing 95% by mass of potassium nitrate and tempered at 400 ℃ for 2 hours; example 44 the glass treated in example 29 was immersed in a third molten salt containing 100% by mass of potassium nitrate and tempered at 360 ℃ for 0.2 hour; in example 45, the glass treated in example 29 was immersed in a third molten salt containing 100% by mass of potassium nitrate and tempered at 440 ℃ for 0.5 hour. Of these, examples 42 to 45 are comparative examples. The CS0, CS10, CS30, CS50, CS100 and Dol0 after the third chemical strengthening treatment were tested in the same manner as in examples 1 to 11. The glass after the third chemical strengthening treatment was tested for four-point bending strength, drop height of 64g steel ball, median drop height of 180-mesh sandpaper and median drop height of 60-mesh sandpaper in the same manner as in examples 20 to 28, and data shown in table 5 below were obtained.
TABLE 5 third time chemical strengthening Process conditions and associated Performance data for glasses
As can be seen from table 5, in examples 37 to 41, after the third chemical strengthening treatment, tempering with high-solubility potassium nitrate in a short time of 0.5 to 1 hour is advantageous for improving the stability of the glass strength, thereby improving the four-point bending strength and the average level of ball drop height of the glass, and also improving the median level of 60-mesh and 180-mesh sandpaper drop. In the third molten salt in example 42, the potassium nitrate content by mass is 90%, which causes rapid reduction in the compressive stress of the treated glass surface, which causes deterioration in mechanical properties such as 4-point bending and ball dropping performance, and reduction in the anti-dropping capability of rough ground; example 45, the tempering treatment is carried out at a high temperature of 440 ℃, so that the internal deep compressive stress of the treated glass is subjected to stress relaxation, the mechanical property of the treated glass is directly reduced, and the anti-falling capability of the rough ground is reduced; example 44, because it was treated for only 0.2 hours, the mechanical properties and the ability to withstand rough ground and falling were not changed; example 43, the tempering treatment was carried out for a long period of 2 hours, resulting in a certain relaxation of the deep stresses in the steel, and a small decrease in the mechanical properties and the resistance to rough ground and falling. Therefore, in the third chemical strengthening treatment, the temperature is preferably 360 to 390 ℃, and the mass percentage of potassium nitrate in the third molten salt is preferably not less than 95%.
Examples 46 to 50
The glass compositions of examples 46 to 50 are specifically shown in Table 6. Of these, examples 48 to 50 are comparative examples.
The glass production processes of examples 46 to 50 are the same as those of example 1, and are not described again.
The chemical strengthening process of the glasses of examples 46 to 50 is the same, and the specific steps are as follows:
(1) first chemical strengthening treatment: the same procedure as the first chemical strengthening treatment in example 1 specifically includes: the glass is subjected to first chemical strengthening treatment for 4 hours in first molten salt with the temperature of 400 ℃, wherein the first molten salt is 100 mass percent of sodium nitrate.
(2) And (3) second chemical strengthening treatment: the same procedure as the second chemical strengthening treatment of example 22 specifically includes: and (3) performing secondary chemical strengthening on the glass subjected to the primary chemical strengthening treatment in second molten salt at the temperature of 420 ℃ for 4 hours, wherein the mass percentage of potassium nitrate in the second molten salt is 100%.
(3) Annealing treatment: the same annealing process as in example 29 specifically includes: and annealing the glass subjected to the second chemical strengthening treatment at 300 ℃ for 1 h.
(4) And (3) chemical strengthening treatment for the third time: the same procedure as the third chemical strengthening treatment in example 38 specifically includes: and (3) carrying out third chemical strengthening treatment on the annealed glass in third molten salt at the temperature of 380 ℃ for 1.0h, wherein the mass percentage of potassium nitrate in the third molten salt is 100%.
The glasses of examples 46 to 50, which were chemically strengthened as described above, were tested for CS0, CS10, CS30, CS50, CS100 and Dol0 in the same manner as in examples 1 to 11. The annealed glass was tested for four-point bending strength, drop height of 64g steel balls, median drop height of 180-mesh sandpaper, and median drop height of 60-mesh sandpaper in the same manner as in examples 20 to 28, and data as shown in Table 6 below were obtained.
TABLE 6 compositions of glasses of examples 46 to 50 and properties of the chemically strengthened glasses
As can be seen from table 6, after the first chemical strengthening treatment, the second chemical strengthening treatment, the annealing treatment and the third chemical strengthening treatment are sequentially performed on the glass of example 46 and example 47, the compressive stress of the surface of the glass is greater than 980MPa, the depth of the pressure layer is greater than 170 micrometers, and the glass has a gradient compressive stress value, so that the glass has excellent mechanical properties and a rough ground resistance and drop resistance; in the glass composition of example 47, the content of alumina is low, the content of silica is high, the proportion of the silica skeleton structure is high, and the network gap is small, so that the ion exchange in the chemical strengthening process is not facilitated, the chemical strengthening efficiency is affected, and the surface compressive stress and the depth of the stress layer of the strengthened glass are small; the glass composition of example 49 had low potassium oxide and sodium oxide content, resulting in a strengthened glass with a K-Na ion exchange layer with a lower stress value, a shallower depth, and a shallow CS layer, which is likely to cause poor microhardness and cracking, resulting in a decrease in the drop resistance of the corresponding product, and also had high magnesium oxide content, high Mg content, and low CS content2+The ion exchange capacity of the glass is seriously hindered, and the depth of a surface compressive stress layer is obviously reduced; the high content of boron oxide in the glass composition of example 50 resulted in a decrease in the ion exchange capacity of the glass, and the zirconium oxide in the glass increased the chemical stability and ion exchange properties of the glass, increased the surface hardness of the glass, and also increased the pressure required to form cracks in the glass, making the glass more scratch and drop resistant, and the absence of zirconium oxide in example 50 resulted in a decrease in the ion exchange properties of the glass.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (12)
1. A chemical strengthening method of glass is characterized by comprising the following steps:
carrying out first chemical strengthening treatment on glass in first molten salt at the temperature of 360-440 ℃ for 2-6 h, wherein the mass percentage of sodium nitrate in the first molten salt is more than or equal to 20%;
carrying out secondary chemical strengthening treatment on the glass subjected to the primary chemical strengthening treatment in second molten salt at the temperature of 380-420 ℃ for 1-4 h, wherein the mass percentage of potassium nitrate in the second molten salt is more than or equal to 80%; and
and annealing the glass subjected to the second chemical strengthening treatment at 260-300 ℃ for 1-4 h.
2. The method for chemically strengthening glass according to claim 1, further comprising, after the step of annealing: and carrying out third chemical strengthening treatment on the annealed glass in third molten salt at the temperature of 360-390 ℃, wherein the mass percentage of potassium nitrate in the third molten salt is not less than 95%.
3. The method for chemically strengthening glass according to claim 2, wherein the time for the third chemical strengthening treatment is 0.5 to 1.0 hour.
4. The method for chemically strengthening glass according to claim 2 or 3, further comprising a step of repeating the alternate annealing treatment and the chemical strengthening treatment on the glass after the step of the third chemical strengthening treatment.
5. The method for chemically strengthening glass according to claim 1, wherein the glass comprises, in mass percent: 55 to 65 percent of SiO213 to 30 percent of Al2O32 to 6 percent of Li2O, 6 to 11 percent of Na2O, 1 to 6 percent of K2O, 0 to 4 percent of MgO, 0 to 3 percent of ZnO and 0.1 to 3.0 percent of B2O30 to 3 percent of P2O5And 0.1 to 4.0% of ZrO2。
6. The method for chemically strengthening glass according to claim 1, wherein the first molten salt contains sodium nitrate in an amount of not less than 40% by mass.
7. The method for chemically strengthening glass according to claim 1, wherein the glass after the first chemical strengthening treatment has a compressive stress layer depth of 80 μm or more and a compressive stress value at 30 μm of 90MPa or more.
8. The chemical strengthening method for glass according to claim 1, wherein the glass after the second chemical strengthening treatment has a surface compressive stress value of 650MPa or more, a compressive stress value at 30 μm of 80MPa or more, and a depth of a compressive stress layer of 100 μm or more.
9. A tempered glass, characterized in that the tempered glass has a surface compressive stress value of at least 970MPa, a compressive stress value at 10 μm of at least 270MPa, a compressive stress value at 30 μm of at least 160MPa, a compressive stress value at 50 μm of at least 95MPa, and a depth of the compressive stress layer of at least 170 μm.
10. The strengthened glass according to claim 9, wherein the strengthened glass is produced by the chemical strengthening method for a glass according to any one of claims 1 to 8.
11. Use of the strengthened glass according to claim 9 or 10 in the manufacture of a display device or in the manufacture of a bullet-proof glass.
12. A display device comprising a cover plate obtained by the strengthened glass processing of claim 9 or 10.
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