A low temperature ion exchange strengthening process for high strength glass

Abstract

The application relates to the field of glass strengthening technology, in particular to a low-temperature ion exchange strengthening process method for high-strength glass. The process method is as follows: S1, glass substrate pretreatment: ultrasonic cleaning and surface activation treatment are carried out on a sodium-calcium silicate glass; S2, low-temperature ion exchange: the pretreated glass is immersed into a salt bath tank containing 350-420 DEG C composite molten salt, and a gradient electric field is applied to the glass for 8-14 hours; S3, cooling: the glass is cooled from the exchange temperature to below 80 DEG C by adopting an air-mist two-phase gradient cooling mode; and S4, water washing and drying to obtain strengthened glass. By the process method, the process time is greatly shortened, the energy consumption is reduced, the performance is obviously improved, and the risk of glass thermal deformation is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of glass strengthening technology, in particular to a low-temperature ion exchange strengthening process for high-strength glass. BACKGROUND

[0002] Glass strengthening technology is an important means to improve the mechanical properties of glass, especially in the field of electronic device screens. With the development of the lightweight trend of electronic devices, higher requirements are placed on the energy consumption and uniformity of glass strengthening processes, and the demand for high-strength glass is increasing. Currently, chemical strengthening methods such as ion exchange are widely used because they can form a compressive stress layer on the surface of the glass. However, traditional ion exchange processes are usually carried out at high temperatures, which consumes a lot of energy and easily leads to uneven stress distribution on the surface of the glass, affecting product yield and service life.

[0003] In the prior art, ion exchange strengthening of high-strength glass is mainly achieved by the following two methods: one is high-temperature ion exchange, which immerses the glass in a molten salt bath and carries out ion exchange at 400-500℃. This method can effectively improve the strength of the glass, but it consumes a lot of energy and easily causes uneven stress. The second is a multi-stage ion exchange method, which adjusts the temperature and time in stages to improve stress distribution, but the process is complex and the cost is high. In addition, there are methods that use auxiliary electric fields or ultrasonic waves to promote ion exchange, but these technologies require large investments in equipment and are difficult to scale up. The defects of the prior art are: high-temperature ion exchange consumes a lot of energy and easily causes uneven stress distribution on the surface of the glass due to temperature gradients; the multi-stage ion exchange method is complex and has high production costs; and the auxiliary means such as electric fields or ultrasonic waves require large investments in equipment and are difficult to popularize.

[0004] In view of the above-mentioned related technologies, there is an urgent need in the art to develop a low-temperature ion exchange strengthening process for high-strength glass to solve the technical problems of high energy consumption, complex process steps, and high production costs of ion exchange processes. SUMMARY

[0005] To solve the technical problems of high energy consumption, complex process steps, and high production costs of ion exchange processes, the present application provides a low-temperature ion exchange strengthening process for high-strength glass.

[0006] The present application provides a low-temperature ion exchange strengthening process for high-strength glass, which adopts the following technical solution: S1 glass substrate pretreatment: ultrasonic cleaning and surface activation treatment are performed on a sodium calcium silicate glass;

[0007] S2 low-temperature ion exchange: the pretreated glass is immersed in a salt bath tank containing 350-420℃ complex molten salt, and a gradient electric field is applied for 8-14 hours;

[0008] S3 cooling: using the gas-liquid two-phase gradient cooling method, the glass is cooled from the exchange temperature to below 80℃;

[0009] S4 post-processing: washing and drying to obtain the strengthened glass.

[0010] The above scheme, by using the electric field driven multi-ion migration one-step method synchronization diffusion, electric field pre-strengthening and gas-liquid two-phase gradient cooling method, the synergy of the three, the process time is greatly shortened, and the performance is significantly improved; 350-420℃ low temperature operation, significantly lower than the traditional KNO3 molten salt exchange temperature, reduces the energy consumption, reduces the risk of glass thermal deformation, produces significant energy saving and cost reduction benefits.

[0011] Preferably, the S1 glass substrate pretreatment, the sodium calcium silicate glass is ultrasonically cleaned and surface activated, including sequentially performing multi-stage ultrasonic cleaning, plasma activation treatment and chemical micro-etching treatment.

[0012] The scheme cooperates three steps of alkaline degreasing, alcohol-water degreasing and megasonic particle removal.

[0013] Preferably, the multi-stage ultrasonic cleaning in the S1 glass substrate pretreatment includes: first-stage alkaline ultrasonic cleaning: using an alkaline solution at 40-50℃, 40kHz frequency for 2-5 minutes; second-stage alcohol-water ultrasonic cleaning: using an alcohol-water solution at 25-35℃ with a frequency of 90-110kHz for 1-3 minutes; third-stage megasonic rinsing: megasonic wave treatment in ultrapure water at a power density of 1-2W / cm 2 for 0.5-2 minutes.

[0014] Preferably, in the multi-stage ultrasonic cleaning, the alkaline cleaning includes the following raw materials by weight percentage: 2-4% NaOH, 0.3-0.7% fatty alcohol polyoxyethylene ether, and deionized water to make up the balance; the alcohol-water solution is 3-7% isopropyl alcohol in ionized water by weight percentage.

[0015] Preferably, the plasma activation treatment in the S1 glass substrate pretreatment adopts the atmospheric pressure dielectric barrier discharge method, and helium-oxygen mixed gas containing 3-8vol% oxygen is introduced at a power of 300-500W for 10-20 seconds.

[0016] Preferably, the chemical micro-etching in the S1 glass substrate pretreatment is treated by etching liquid at a temperature of 20-30℃ for 20-40 seconds, and the etching liquid includes the following raw materials by weight percentage: ammonium bifluoride 1-2%, sulfuric acid 0.5-1%, polyethylene glycol 0.05-0.15%, and the rest is deionized water.

[0017] Preferably, the composite molten salt in the S2 low-temperature ion exchange comprises the following raw materials by weight percentage: 86-90% KNO3, 4-6% CsNO3, 4-6% SrCl2, and 1-3% CeO2 nanoparticles, wherein the CeO2 nanoparticles have a particle size of 30-50 nm.

[0018] The above scheme completes K in one step. + Cs + 、Sr 2+ Exchange, via Cs + The addition of Sr forms a deeper compressive stress layer and higher surface compressive stress on the glass surface. 2+ The dual charge of Sr serves two purposes: firstly, it lowers the melting point of the molten salt or improves its fluidity; secondly, it... 2+ It participates in surface modification, filling tiny defects or forming a denser surface layer; thirdly, Cl - Ions help suppress the negative effects of impurities in molten salts or promote ion exchange through slight surface etching; nano-CeO2 inhibits Cs. + 、Sr 2+ The resulting volume expansion cracks improve surface integrity, thereby enhancing the impact and scratch resistance of the final strengthened glass, while also promoting K... + Cs + Diffusion into the glass interior. Surface compressive stress >1000MPa, stress layer depth >50μm can be achieved at 350-420℃, with a composite stable design life of 1200 hours.

[0019] Preferably, the gradient electric field in the S2 low-temperature ion exchange is implemented as follows: a segmented adjustable electrode group is set in the salt bath, which is divided into 4 independent adjustable electrode groups; along the glass transport direction, the electric field strength increases linearly from 0.5kV / cm at the inlet end to 2.0kV / cm at the outlet end.

[0020] The above scheme applies an electric field during ion exchange to directionally drive ion migration, significantly accelerating the ion exchange rate, compensating for the rate decrease caused by low temperature, and more effectively transferring K+ ions. + Cs + By pressing it into the glass, a deeper stress layer is formed, potentially resulting in a steeper stress distribution.

[0021] Preferably, in the S2 low-temperature ion exchange, the gradient electric field has an anode consisting of a Ta / IrO2 coated titanium plate and a cathode consisting of a porous silicon carbide plate, and the cathode is a porous silicon carbide plate with a porosity of 40-60%, a pore size of 5-20 μm, and a resistivity of ≤0.1 Ω·cm.

[0022] Preferably, the gas-atomized two-phase gradient cooling in the S3 cooling step includes: a first-stage gas cooling: in the range of 350-220℃, the cooling rate is 5-10℃ / min, and the gas recovered from the annealing kiln waste heat is used as the cooling medium; and a second-stage atomized cooling: in the range of 220-80℃, a mixed medium of compressed air and ultra-pure water mist is used for jet cooling, the atomizing pressure is 0.3-0.8MPa, the water mist particle size is ≤10μm, and the cooling rate is 20-50℃ / min.

[0023] Through the gas-atomized two-phase gradient cooling process, the energy recovery is coupled with the phase change cooling regulation, which solves the technical problem of the glass strengthening cooling link. In the first stage of 350-220℃, the recovered annealing kiln waste heat gas is used for relatively moderate cooling, which is obviously different from the direct discharge of the waste heat gas in the traditional process, and can save energy and protect the environment, and can also avoid excessive thermal stress or uneven stress distribution caused by rapid cooling in the high-temperature zone. In the second stage of 220-80℃, compressed air and ultra-pure water mist are mixed and sprayed for rapid cooling, and the water mist particle size ≤10μm ensures good heat conduction efficiency and uniformity, and avoids large water droplet impact or local supercooling.

[0024] Preferably, in the atomized cooling stage of the S3 cooling step, the cooling rate is dynamically adjusted according to the glass thickness: when the thickness ≤3mm, the cooling rate is 40-50℃ / min; when 3mm

[0025] The cooling rate is dynamically adjusted according to the thickness, which is a key point of the cooling process, and solves the different thermal stress challenges faced by glasses of different thicknesses during rapid cooling. Thin glass (≤3mm) allows the highest cooling rate of 40-50℃ / min, fully utilizes its fast heat dissipation characteristics, maximizes the effect of "freezing" stress, and improves the strength. Medium-thick glass (3-6mm) uses a moderate cooling rate of 30-40℃ / min to balance between ensuring stress freezing effect and controlling thermal stress risk; thick glass (>6mm) uses a relatively slow cooling rate of 20-30℃ / min to prioritize ensuring cooling uniformity and avoiding internal stress burst caused by excessive core-surface temperature difference.

[0026] The scheme generates higher surface compressive stress and greater compressive stress layer depth through the synergistic process of "low-temperature composite molten salt formula", "gradient electric field driving" and "gas-atomized two-phase cooling", wherein the CeO2 nanoparticles significantly improve the surface microstructure, inhibit the initiation and expansion of micro-cracks, and improve the impact resistance, bending resistance and scratch resistance; the controllable gradient cooling effectively "freezes" the strengthening stress and maximally reduces the destructive thermal stress introduced in the cooling process, thereby ensuring the yield and performance stability of the finished product. The high-strength glass prepared by the low-temperature ion exchange strengthening process for high-strength glass has a surface compressive stress CS≥1000 MPa, a stress layer depth DOL≥45 μm, and a warpage≤0.35 mm / m; under the process condition of 380℃ / 14h, the ion exchange energy consumption is≤2.0 kWh / kg. The process is suitable for the strengthening treatment of smart phone and tablet cover glass, and has the characteristics of low energy consumption, high uniformity and simple process.

[0027] In summary, the present application has the following beneficial effects:

[0028] 1. The present application generates higher surface compressive stress and greater compressive stress layer depth through the synergistic process of "low-temperature composite molten salt formula", "gradient electric field driving" and "gas-atomized two-phase cooling", wherein the CeO2 nanoparticles significantly improve the surface microstructure, inhibit the initiation and expansion of micro-cracks, and improve the impact resistance, bending resistance and scratch resistance; the controllable gradient cooling effectively "freezes" the strengthening stress and maximally reduces the destructive thermal stress introduced in the cooling process, thereby ensuring the yield and performance stability of the finished product.

[0029] 2. The high-strength glass prepared by the low-temperature ion exchange strengthening process for high-strength glass has a surface compressive stress CS≥1000 MPa, a stress layer depth DOL≥45 μm, and a warpage≤0.35 mm / m; under the process condition of 380℃ / 12h, the ion exchange energy consumption is≤2.0 kWh / kg.

[0030] 3. The low-temperature ion exchange strengthening process for high-strength glass of the present application is suitable for the strengthening treatment of smart phone and tablet cover glass, and has the characteristics of low energy consumption, high uniformity and simple process. DETAILED DESCRIPTION

[0031] The technical scheme of the present application is further illustrated by specific embodiments, and the specific embodiments do not represent a limitation on the protection scope of the present application; some non-essential modifications and adjustments made by others according to the concept of the present application still belong to the protection scope of the present application.

[0032] The test methods shown in the following examples are conventional methods, unless otherwise specified. The reagents and materials shown are commercially available.

[0033] The application will be further described in detail below in conjunction with examples and comparative examples.

[0034] Preparation Example

[0035] Preparation of etching solution

[0036] 1 g of polyethylene glycol was weighed into 800 g of deionized water and stirred to dissolve; 8 g of sulfuric acid was slowly added dropwise into the polyethylene glycol aqueous solution and stirred to dissolve, and cooled to room temperature; 15 g of ammonium hydrogen fluoride was added and stirred to dissolve, deionized water was added to a total weight of 1000 g, and left to mature for 24 hours.

[0037] Preparation of etching solution

[0038] 0.5 g of polyethylene glycol was weighed into 800 g of deionized water and stirred to dissolve; 10 g of sulfuric acid was slowly added dropwise into the polyethylene glycol aqueous solution and stirred to dissolve, and cooled to room temperature; 10 g of ammonium hydrogen fluoride was added and stirred to dissolve, deionized water was added to a total weight of 1000 g, and left to mature for 24 hours.

[0039] Preparation of etching solution

[0040] 1.5 g of polyethylene glycol was weighed into 800 g of deionized water and stirred to dissolve; 5 g of sulfuric acid was slowly added dropwise into the polyethylene glycol aqueous solution and stirred to dissolve, and cooled to room temperature; 20 g of ammonium hydrogen fluoride was added and stirred to dissolve, deionized water was added to a total weight of 1000 g, and left to mature for 24 hours.

[0041] Preparation of composite molten salt

[0042] KNO3 88 kg, CsNO3 5.1 kg, and SrCl2 5.3 kg were sequentially added to a nickel-based alloy crucible, heated to 350°C, and stirred until completely molten; then 1.9 kg of CeO2 nanoparticles were added, and mechanical stirring was continued at 400°C for 2 hours, and the undispersed CeO2 agglomerates were removed by filtration through a high-temperature filter screen with a pore size of ≤10 μm.

[0043] Preparation of composite molten salt

[0044] KNO3 86 kg, CsNO3 6 kg, and SrCl2 4 kg were sequentially added to a nickel-based alloy crucible, heated to 350°C, and stirred until completely molten; then 1 kg of CeO2 nanoparticles were added, and mechanical stirring was continued at 400°C for 2 hours, and the undispersed CeO2 agglomerates were removed by filtration through a high-temperature filter screen with a pore size of ≤10 μm.

[0045] Preparation of composite molten salt

[0046] KNO3 90kg, CsNO3 4kg and SrCl2 6kg were sequentially added in a nickel-based alloy crucible, and the temperature was raised to 350℃, and stirred until completely melted; then 3kg of CeO2 nanoparticles were added, and mechanical stirring was continued at 400℃ for 2 hours, and the non-dispersed CeO2 agglomerates were removed by filtering through a high-temperature filter screen with a pore size of ≤10μm.

[0047] Embodiment

[0048] Embodiment 1

[0049] A low-temperature ion exchange strengthening process for high-strength glass adopts the following technical solutions:

[0050] S1 glass substrate pretreatment: ultrasonic cleaning and surface activation treatment are performed on the soda-lime silicate glass, including sequentially performing multi-stage ultrasonic cleaning, plasma activation treatment and chemical micro-etching treatment;

[0051] The multi-stage ultrasonic cleaning includes: first-stage alkaline ultrasonic cleaning: using alkaline cleaning, 3 minutes at 45℃ and 40kHz frequency; second-stage alcohol water ultrasonic cleaning: using alcohol water solution, 2 minutes at 30℃ and 100kHz frequency; third-stage megasonic rinsing: 1 minute in ultrapure water at 2W / cm 2 power density megasonic treatment for 1 minute;

[0052] Plasma activation treatment: helium-oxygen mixed gas containing 5vol% oxygen is introduced, and treatment is performed at 400W power for 15 seconds;

[0053] Chemical micro-etching: treatment is performed by etching liquid at 25℃ for 30 seconds;

[0054] S2 low-temperature ion exchange: the pretreated glass is immersed in a salt bath tank containing 380℃ composite molten salt, a segmented adjustable electrode group is arranged in the salt bath tank, and the salt bath tank is divided into 4 independent adjustable electrode groups; along the glass transmission direction, the electric field strength linearly increases from the inlet end 0.5kV / cm to the outlet end 2.0kV / cm, the first electrode group: 0.68kV / cm, the second electrode group: 1.06kV / cm, the third electrode group: 1.43kV / cm, the fourth electrode group: 1.81kV / cm, the inlet end s=0, the electric field strength 0.5kV / cm and the outlet end s=1, the electric field strength 2.0kV / cm are boundary points, which do not directly correspond to the center of any electrode group, but are covered by adjacent electrode groups; a gradient electric field is applied for 12 hours;

[0055] S3 cooling: adopt gas-atomized two-phase gradient cooling method, first stage gas cooling: in 350-220℃ interval, cooling rate 8℃ / min, use the gas recovered from annealing kiln as cooling medium; second stage atomized cooling: in 220-80℃ interval, use mixed medium of compressed air and super-pure water atomized spray cooling, atomized pressure 0.5MPa, when thickness≤3mm, cooling rate 50℃ / min; when 3mm

[0056] S4 post-treatment: water washing and drying to obtain strengthened glass.

[0057] The alkaline cleaning solution is 30g NaOH, 5g fatty alcohol polyoxyethylene ether, and deionized water is added to 1000mL;

[0058] The alcohol aqueous solution is 50g isopropyl alcohol dissolved in deionized water, and the volume is made up to 1000mL.

[0059] The etching solution is prepared by Preparation Example 1, and the composite molten salt is prepared by Preparation Example 4.

[0060] Example 2

[0061] A low-temperature ion exchange strengthening process for high-strength glass, which adopts the following technical scheme:

[0062] S1 glass substrate pretreatment: ultrasonic cleaning and surface activation treatment are performed on the soda-lime-silicate glass, including sequentially performing multi-stage ultrasonic cleaning, plasma activation treatment and chemical micro-etching treatment;

[0063] The multi-stage ultrasonic cleaning includes: first-stage alkaline ultrasonic cleaning: using alkaline cleaning, 40℃, 40kHz frequency treatment for 5 minutes; second-stage alcohol water ultrasonic cleaning: using alcohol aqueous solution, 25℃, 110kHz frequency treatment for 3 minutes; third-stage megasonic rinsing: in ultrapure water, 2W / cm 2 Megasonic wave treatment with power density 0.5 minutes;

[0064] Plasma activation treatment: helium-oxygen mixed gas containing 3vol% oxygen is introduced, and treatment is performed at 500W power for 10 seconds;

[0065] Chemical micro-etching: treatment by etching solution at 20℃ for 40 seconds;

[0066] S2 Low-Temperature Ion Exchange: The pretreated glass is immersed in a salt bath containing 350℃ composite molten salt. A segmented adjustable electrode group is set in the salt bath, which is divided into 4 independent adjustable electrode groups. Along the glass transport direction, the electric field strength increases linearly from 0.5kV / cm at the inlet end to 2.0kV / cm at the outlet end, and a gradient electric field treatment is applied for 14 hours.

[0067] S3 Cooling: Employs a two-phase gradient cooling method using air and mist. The first stage, air cooling, operates at a rate of 5℃ / min within the 350-220℃ range, using gas recovering waste heat from the annealing furnace as the cooling medium. The second stage, mist cooling, operates within the 220-80℃ range, employing a mixture of compressed air and ultrapure water mist for jet cooling. The atomization pressure is 0.3MPa, and the water mist particle size is ≤10μm. When the thickness is ≤3mm, the cooling rate is 40℃ / min; when 3mm < thickness ≤6mm, the cooling rate is 30℃ / min; and when the thickness >6mm, the cooling rate is 20℃ / min. This process cools the glass from its exchange temperature to below 80℃.

[0068] S4 post-processing: water washing and drying to obtain tempered glass.

[0069] The alkaline cleaning solution consists of 20g NaOH, 3g fatty alcohol polyoxyethylene ether, and deionized water to a final volume of 1000mL.

[0070] The alcohol-water solution was prepared by dissolving 30g of isopropanol in deionized water and bringing the volume to 1000mL.

[0071] The etching solution was prepared in Preparation Example 2, and the composite molten salt was prepared in Preparation Example 5.

[0072] Example 3

[0073] A low-temperature ion exchange strengthening process for high-strength glass adopts the following technical solution:

[0074] S1 glass substrate pretreatment: Sodium-calcium silicate glass is subjected to ultrasonic cleaning and surface activation treatment, including sequential multi-stage ultrasonic cleaning, plasma activation treatment and chemical micro-etching treatment.

[0075] Multi-stage ultrasonic cleaning includes: Stage 1 alkaline ultrasonic cleaning: using alkaline cleaning solution, treated at 50℃ and 40kHz frequency for 2 minutes; Stage 2 alcohol-water ultrasonic cleaning: using an alcohol-water solution, treated at 35℃ and 90kHz frequency for 1 minute; Stage 3 megasonic rinsing: rinsing in ultrapure water at 1W / cm². 2 Power density megasonic processing for 2 minutes;

[0076] Plasma activation treatment: A helium-oxygen mixture containing 8 vol% oxygen is introduced and treated for 20 seconds at a power of 300W;

[0077] Chemical micro-etching: the glass substrate was treated by etching solution at 30℃ for 20 seconds;

[0078] S2 Low temperature ion exchange: the pretreated glass was immersed into a salt bath containing 420℃ compound molten salt, and a segmented adjustable electrode group was arranged in the salt bath, which was divided into four independent adjustable electrode groups; along the glass transmission direction, the electric field strength linearly increased from the inlet end 0.5kV / cm to the outlet end 2.0kV / cm, the first electrode group: 0.68kV / cm, the second electrode group: 1.06kV / cm, the third electrode group: 1.43kV / cm, the fourth electrode group: 1.81kV / cm, the inlet end s = 0, the electric field strength 0.5kV / cm and the outlet end s = 1, the electric field strength 2.0kV / cm are boundary points, which do not directly correspond to the center of any electrode group, but are covered by adjacent electrode groups; the gradient electric field was applied for 8 hours;

[0079] S3 Cooling: the gas-liquid two-phase gradient cooling method was adopted, the first stage gas cooling: in the interval of 350-220℃, the cooling rate was 10℃ / min, and the gas recovered from the annealing kiln was used as the cooling medium; the second stage mist cooling: in the interval of 220-80℃, the mixed medium of compressed air and ultra-pure water mist was used for jet cooling, the atomizing pressure was 0.8MPa, the water mist particle size was ≤10μm, when the thickness was ≤3mm, the cooling rate was 40℃ / min; when 3mm < thickness ≤6mm, the cooling rate was 40℃ / min; when the thickness was >6mm, the cooling rate was 30℃ / min, and the glass was cooled from the exchange temperature to below 80℃;

[0080] S4 Post-treatment: the strengthened glass was obtained by water washing and drying.

[0081] The etching solution was prepared by Preparation Example 3, and the compound molten salt was prepared by Preparation Example 6.

[0082] The alkaline cleaning was 40g NaOH, 7g fatty alcohol polyoxyethylene ether, and deionized water was added to 1000mL;

[0083] The alcohol aqueous solution was 70g isopropyl alcohol dissolved in deionized water, and the volume was added to 1000mL.

[0084] Example 4

[0085] A low temperature ion exchange strengthening process method for high strength glass adopts the following technical scheme:

[0086] S1 Glass substrate pretreatment: the sodium calcium silicate glass was subjected to ultrasonic cleaning and surface activation treatment, including sequentially performing multistage ultrasonic cleaning, plasma activation treatment and chemical micro-etching treatment;

[0087] The multi-stage ultrasonic cleaning includes: a first-stage alkaline ultrasonic cleaning: using alkaline cleaning, treating at 40 kHz frequency for 2 minutes at 40℃; a second-stage alcohol water ultrasonic cleaning: using alcohol water solution, treating at 90 kHz frequency for 1 minute at 25℃; a third-stage megasonic rinsing: treating in ultrapure water at 1 W / cm 2 megasonic wave treatment at a power density of 0.5 minutes;

[0088] plasma activation treatment: passing 3 vol% oxygen-containing helium-oxygen mixed gas, treating at 300 W power for 10 seconds;

[0089] chemical micro-etching: treating by etching liquid at 20℃ for 20 seconds;

[0090] S2 low-temperature ion exchange: immersing the pretreated glass in a salt bath tank containing 380℃ composite molten salt, setting a segmented adjustable electrode group in the salt bath tank, dividing into 4 independent adjustable electrode groups; along the glass transmission direction, the electric field strength linearly increases from 0.5 kV / cm at the inlet end to 2.0 kV / cm at the outlet end, applying a gradient electric field for 10 hours;

[0091] S3 cooling: adopting a gas-liquid two-phase gradient cooling method, a first-stage gas cooling: in the 350-220℃ interval, the cooling rate is 7℃ / min, using the gas recovered from the annealing kiln as the cooling medium; a second-stage mist cooling: in the 220-80℃ interval, using the mixed medium of compressed air and ultrapure water mist for jet cooling, the atomizing pressure is 0.4 MPa, the water mist particle size is ≤10 μm, when the thickness is ≤3 mm, the cooling rate is 50℃ / min; when 3 mm

[0092] S4 post-treatment: washing and drying to obtain the strengthened glass.

[0093] The etching liquid is prepared by Preparation Example 1, and the composite molten salt is prepared by Preparation Example 5.

[0094] The alkaline cleaning is 30 g of NaOH, 7 g of fatty alcohol polyoxyethylene ether, and deionized water to 1000 mL;

[0095] The alcohol water solution is 50 g of isopropyl alcohol dissolved in deionized water, and the volume is made up to 1000 mL.

[0096] Example 5

[0097] A low-temperature ion exchange strengthening process method for high-strength glass adopts the following technical scheme:

[0098] S1 glass substrate pretreatment: ultrasonic cleaning and surface activation treatment are performed on the sodium calcium silicate glass, including sequentially performing multi-stage ultrasonic cleaning, plasma activation treatment and chemical micro-etching treatment;

[0099] The multi-stage ultrasonic cleaning includes: first-stage alkaline ultrasonic cleaning: using alkaline cleaning, 40 kHz frequency at 50°C for 5 minutes; second-stage alcohol water ultrasonic cleaning: using alcohol water solution, 110 kHz frequency at 35°C for 3 minutes; third-stage megasonic rinsing: 2 W / cm 2 megasonic wave treatment at a power density of 2 W / cm

[0100] The plasma activation treatment: helium-oxygen mixed gas containing 8 vol% oxygen is introduced, and treatment is performed at a power of 500 W for 20 seconds;

[0101] The chemical micro-etching: treatment is performed by etching liquid at a temperature of 30°C for 40 seconds;

[0102] S2 low-temperature ion exchange: the pretreated glass is immersed in a salt bath tank containing a 400°C composite molten salt, a segmented adjustable electrode group is arranged in the salt bath tank, and the salt bath tank is divided into four independent adjustable electrode groups; along the glass transmission direction, the electric field strength linearly increases from the inlet end 0.5 kV / cm to the outlet end 2.0 kV / cm, the first electrode group: 0.68 kV / cm, the second electrode group: 1.06 kV / cm, the third electrode group: 1.43 kV / cm, the fourth electrode group: 1.81 kV / cm, the inlet end s = 0, the electric field strength 0.5 kV / cm and the outlet end s = 1, the electric field strength 2.0 kV / cm are boundary points, which do not directly correspond to the center of any electrode group, but are covered by adjacent electrode groups; a gradient electric field is applied for 12 hours;

[0103] S3 cooling: an air-liquid two-phase gradient cooling method is adopted, the first stage air cooling: in the interval of 350-220°C, the cooling rate is 9°C / min, and the gas recovered from the annealing kiln is used as the cooling medium; the second stage mist cooling: in the interval of 220-80°C, a mixed medium of compressed air and super pure water mist is used for jet cooling, the atomizing pressure is 0.7 MPa, the water mist particle size is ≤10 μm, when the thickness is ≤3 mm, the cooling rate is 40°C / min; when 3 mm < thickness ≤6 mm, the cooling rate is 30°C / min; when the thickness is >6 mm, the cooling rate is 30°C / min, and the glass is cooled from the exchange temperature to below 80°C;

[0104] S4 post-treatment: water washing and drying to obtain the strengthened glass.

[0105] The etching liquid is prepared by Preparation Example 2, and the composite molten salt is prepared by Preparation Example 4.

[0106] The basic cleaning is 40 g of NaOH, 3 g of fatty alcohol polyoxyethylene ether, and deionized water is added to 1000 mL.

[0107] The alcohol aqueous solution, 60 g of isopropyl alcohol is dissolved in deionized water, and is added to 1000 mL.

[0108] Comparative Example

[0109] Comparative Example 1

[0110] The same as Example 1, except that the composition of the complex molten salt in step S2 low temperature ion exchange is different, the complex molten salt: KNO3 88 kg and SrCl2 10 kg are sequentially added in a nickel-based alloy crucible, heated to 350℃, and stirred until completely melted; then add 2 kg of CeO2 nanoparticles, continuously mechanically stir at 400℃ for 2 hours, filter through a high temperature filter screen with a pore size ≤10 μm, remove the undispersed CeO2 agglomerates.

[0111] Comparative Example 2

[0112] The same as Example 1, except that the composition of the complex molten salt in step S2 low temperature ion exchange is different, the complex molten salt: KNO3 93 kg, CsNO3 5 kg are sequentially added in a nickel-based alloy crucible, heated to 350℃, and stirred until completely melted; then add 2 kg of CeO2 nanoparticles, continuously mechanically stir at 400℃ for 2 hours, filter through a high temperature filter screen with a pore size ≤10 μm, remove the undispersed CeO2 agglomerates.

[0113] Comparative Example 3

[0114] The same as Example 1, except that the cooling method in step S3 is different, the cooling uses pure nitrogen gas fast cooling, 20℃ / min.

[0115] Comparative Example 4

[0116] The same as Example 1, except that the cooling method in step S3 is different, the cooling uses traditional water quenching, 100℃ / min.

[0117] Comparative Example 5

[0118] The same as Example 1, except that the electric field conditions in step S2 are different, the electric field conditions are uniform electric field, 1.2 kV / cm constant.

[0119] Comparative Example 6

[0120] The same as Example 1, except that the ion exchange temperature in step S2 is 330℃.

[0121] Comparative Example 7

[0122] The same as example 1, except that the ion exchange temperature of step S2 is 450℃.

[0123] Performance detection test

[0124] The high-strength glass prepared by examples 1-5 and comparative examples 1-7 is subjected to performance detection, surface stress, stress layer depth, tested according to GB / T30100-2013《Glass materials surface stress test method》; warpage, tested according to GB / T30101-2013《Flat plate glass flatness test method》; burst rate, reference GB / T 30020-2013《Glass materials fracture toughness test method》destructive test. The test results are shown in Table 1.

[0125] Table 1 high-strength glass performance detection results

[0126]

[0127] As shown in Table 1, the high-strength glass prepared by examples 1-5, the surface compressive stress CS≥1000MPa, the stress layer depth DOL≥45μm, the warpage≤0.35mm / m; the ion exchange energy consumption of example 1 under the process condition of 380℃ / 12h≤2.0kWh / kg.

[0128] The detection results of comparative example 1 and comparative example 2 show that when the content of Cs + The absence of large ion substitution effect results in a sharp drop in surface compressive stress, CS=720MPa; when the content of Sr 2+ The absence of large ion substitution effect results in a sharp drop in surface compressive stress, CS=720MPa; when the content of Sr

[0129] From the above test results, the low-temperature ion exchange strengthening process for high-strength glass can generate higher surface compressive stress and greater compressive stress layer depth through the synergistic process of "low-temperature composite molten salt formula", "gradient electric field driving" and "gas-liquid two-phase cooling", wherein the CeO2 nanoparticles significantly improve the surface microstructure, inhibit the initiation and expansion of microcracks, and improve the impact resistance, bending resistance and scratch resistance; the controllable gradient cooling effectively "freezes" the strengthening stress and maximally reduces the destructive thermal stress introduced in the cooling process, thereby ensuring the yield and performance stability of the finished product. The method is suitable for the strengthening treatment of cover glass for smart phones and tablets, and has the characteristics of low energy consumption, high uniformity and simple process.

[0130] The embodiments are only an explanation of the present application, and are not a limitation of the present application. Those skilled in the art can make modifications to the embodiments without creative contribution, according to the needs, as long as the modifications are within the scope of the present application.

Claims

1. A low-temperature ion exchange strengthening process for high-strength glass, characterized in that, The following technical solution is adopted: S1 Glass substrate pretreatment: Sodium-calcium silicate glass is subjected to ultrasonic cleaning and surface activation treatment; S2 Low-temperature ion exchange: The pretreated glass is immersed in a salt bath containing composite molten salt at 350-420℃, and a gradient electric field is applied for treatment for 8-14 hours. S3 Cooling: Employs a two-phase gradient cooling method using air mist to cool the glass from the exchange temperature to below 80°C; S4 Post-processing: Wash and dry to obtain tempered glass; The composite molten salt in the S2 low-temperature ion exchange comprises the following raw materials by weight percentage: KNO3 86-90%, CsNO3 4-6%, SrCl2 4-6%, CeO2 nanoparticles 1-3%, wherein the particle size of the CeO2 nanoparticles is 30-50nm. The implementation method of the gradient electric field in the S2 low-temperature ion exchange is as follows: a segmented adjustable electrode group is set in the salt bath, which is divided into 4 independent adjustable electrode groups; along the glass transport direction, the electric field strength increases linearly from 0.5kV / cm at the inlet end to 2.0kV / cm at the outlet end. The S3 cooling step includes two-phase gradient cooling of gas and mist: the first stage is gas cooling: in the range of 350-220℃, the cooling rate is 5-10℃ / min, and the gas that recovers the waste heat of the annealing furnace is used as the cooling medium; the second stage is mist cooling: in the range of 220-80℃, a mixed medium of compressed air and ultrapure water mist is used for spray cooling, the atomization pressure is 0.3-0.8MPa, the water mist particle size is ≤10μm, and the cooling rate is 20-50℃ / min.

2. The low-temperature ion exchange strengthening process for high-strength glass according to claim 1, characterized in that, S1 glass substrate pretreatment involves ultrasonic cleaning and surface activation of the sodium-calcium silicate glass, including sequential multi-stage ultrasonic cleaning, plasma activation treatment, and chemical micro-etching treatment.

3. The low-temperature ion exchange strengthening process for high-strength glass according to claim 2, characterized in that, The S1 glass substrate pretreatment includes multi-stage ultrasonic cleaning, comprising: a first-stage alkaline ultrasonic cleaning: using an alkaline solution at 40-50℃ and 40kHz for 2-5 minutes; a second-stage alcohol-water ultrasonic cleaning: using an alcohol-water solution at 25-35℃ and 90-110kHz for 1-3 minutes; and a third-stage megasonic rinsing: rinsing in ultrapure water at 1-2W / cm². 2 Megohmsonic processing at power density for 0.5-2 minutes.

4. The low-temperature ion exchange strengthening process for high-strength glass according to claim 2, characterized in that, The plasma activation treatment in the S1 glass substrate pretreatment adopts atmospheric pressure dielectric barrier discharge mode, and a helium-oxygen mixture containing 3-8 vol% oxygen is introduced and treated for 10-20 seconds at a power of 300-500W.

5. The low-temperature ion exchange strengthening process for high-strength glass according to claim 2, characterized in that, The S1 glass substrate pretreatment involves chemical micro-etching, which is performed by treating the substrate with an etching solution at a temperature of 20-30°C for 20-40 seconds. The etching solution comprises the following raw materials by weight percentage: ammonium bifluoride 1-2%, sulfuric acid 0.5-1%, polyethylene glycol 0.05-0.15%, and the remainder being deionized water.

6. The low-temperature ion exchange strengthening process for high-strength glass according to claim 1, characterized in that: In the S3 cooling step, during the fog cooling stage, the cooling rate is dynamically adjusted according to the glass thickness: when the thickness is ≤3mm, the cooling rate is 40-50℃ / min; when the thickness is ≤6mm, the cooling rate is 30-40℃ / min; and when the thickness is >6mm, the cooling rate is 20-30℃ / min.

7. The low-temperature ion exchange strengthening process for high-strength glass according to claim 1, characterized in that: The prepared reinforced glass has a surface compressive stress CS≥1000MPa, a stress layer depth DOL≥45μm, and a warpage ≤0.35mm / m; under the process conditions of 380℃ / 12h, the ion exchange energy consumption is ≤2.0kWh / kg.

Images