A microwave-assisted glass strengthening process

Abstract

The present application relates to the technical field of glass strengthening, in particular to a microwave-assisted glass strengthening process, comprising the following steps: (1) preheating stage: preheat the glass by microwave, heat to 300-350 DEG C, preheat for 30-60 min; (2) shallow layer exchange stage: put the glass into the first molten salt, strengthen at 390-410 DEG C for 1-2 h, and at the same time, use low-frequency microwave-assisted strengthening; (3) deep layer exchange stage: put the glass into the second molten salt, strengthen at 420-430 DEG C for 3-4 h, and at the same time, use high-frequency microwave-assisted strengthening. The present application can avoid the micro-cracks caused by local overheating by using microwave-assisted strengthening glass and reducing the temperature difference between the surface and the interior through the microwave penetration, thereby improving the uniformity of the ion exchange layer and being suitable for the strengthening of various shaped glasses; the microwave directly acts on the reactants, which can shorten the ion exchange time by 40%-60%, reduce energy consumption and improve efficiency.

Description

Technical Field

[0001] This invention relates to the field of glass strengthening technology, and specifically to a microwave-assisted glass strengthening process. Background Technology

[0002] Chemically strengthened glass products are widely used in electronic fields such as mobile phones, watches, computers, and touch panels due to their excellent light transmittance and superior touch and feel. As the requirements for the bending resistance and hardness of strengthened glass continue to increase, the strengthening process has become increasingly complex. Currently, the glass processing industry generally requires strengthened glass products to have high DOL (Density Oxide) and high CS (Scratch Resistance) values, but a single strengthening process generally cannot simultaneously meet these two values, thus failing to satisfy user performance requirements. To further improve the DOL and CS values ​​of strengthened glass, thereby enhancing its bending resistance and scratch resistance, a two-stage strengthening process is typically employed to treat the glass, thereby better extending product lifespan.

[0003] Chinese invention patent application number 201911217898.7 discloses a glass strengthening process that can reduce warping and dimensional expansion. The process includes a first strengthening and a second strengthening: (1) First strengthening: the glass is placed in a molten salt containing a low concentration of potassium nitrate and strengthened at a temperature of 375-385℃ for 9-11 hours; (2) Second strengthening: the glass after the first strengthening is placed in a molten salt containing a high concentration of potassium nitrate and strengthened at a temperature of 405-415℃ for 1.5-2.5 hours. The strengthening process of this invention adopts a two-step method. The first step is to slowly strengthen the glass in a molten salt containing a low concentration of potassium nitrate to obtain a suitable stress layer compression depth. The second step is to quickly strengthen the glass in a molten salt containing a high concentration of potassium nitrate to obtain a suitable compressive stress on the glass surface. This can reduce glass warping and avoid dimensional expansion during glass strengthening. The steps are simple and the operation is convenient. However, the two-stage strengthening process takes a long time, consumes a lot of energy, and is costly. Traditional heating methods conduct heat from the outside to the inside, which can easily lead to a large temperature difference between the glass surface and the inside, causing local stress concentration or micro-cracks, affecting the yield of 3D curved glass or irregularly shaped glass covers. Summary of the Invention

[0004] In order to overcome the shortcomings and deficiencies of the existing technology, the purpose of this invention is to provide a microwave-assisted glass strengthening process. This strengthening process uses microwave-assisted strengthening, which not only ensures the glass strengthening effect, but also shortens the glass strengthening time, reduces energy consumption, lowers costs, and improves efficiency. At the same time, microwaves uniformly heat the inside and outside of the glass, reducing temperature gradients and avoiding microcracks. It is suitable for strengthening various irregularly shaped glasses.

[0005] The objective of this invention is achieved through the following technical solution: a microwave-assisted glass strengthening process, comprising the following steps:

[0006] (1) Preheating stage: Preheat the glass with microwave to 300-350℃ for 30-60 minutes;

[0007] (2) Shallow exchange stage: The glass is placed in the first molten salt and strengthened at 390-410℃ for 1-2 hours, while low-frequency microwave-assisted strengthening is used at the same time.

[0008] (3) Deep exchange stage: The glass is placed in the second molten salt and strengthened at 420-430℃ for 3-4 hours, while high-frequency microwave-assisted strengthening is used.

[0009] The strengthening process of this invention uses microwave-assisted glass strengthening. Microwave penetrating heating reduces the temperature difference between the surface and the interior, which can avoid microcracks caused by local overheating, thereby improving the uniformity of the ion exchange layer. It is suitable for strengthening various irregularly shaped glasses. Microwaves act directly on the reactants, which can shorten the ion exchange time by 40%-60%, reduce energy consumption, lower costs, and also deepen the stress layer.

[0010] Preferably, in step (2), the first molten salt comprises the following raw materials by weight percentage: KNO3: 64%-76%, NaNO3: 20%-34%, and NaOH: 2%-4%. NaOH can ionize OH- in the molten state. - OH - As a polar molecule, Na can enhance the bonding between molten salt and glass under microwave influence. + / K + The ion exchange rate can shorten the strengthening time and increase the depth of the compressive stress layer.

[0011] Preferably, in step (3), the second molten salt comprises the following raw materials by weight percentage: KNO3: 68%-79%, NaNO3: 16%-24%, NaOH: 1%-3%, KOH: 2%-3%, and NaHCO3: 1%-3%. NaOH and KOH can ionize to release OH- in the molten state. - OH - As a polar molecule, Na can enhance the bonding between molten salt and glass under microwave influence. + / K + The ion exchange rate is increased, the strengthening time is shortened, and the compressive stress layer depth is deepened. The addition of NaHCO3 can prevent the glass surface from being corroded by excessive NaOH and KOH.

[0012] Preferably, in step (2), the microwave frequency is 2.1-2.8 GHz and the power density is 0.5-2 W / cm². 3 In step (3), the microwave frequency is 3.9-6.1 GHz and the power density is 1.2-3 W / cm². 3Microwaves can increase the ion exchange rate between glass and molten salt, shortening the glass strengthening time. Compared with traditional strengthening time, the introduction of microwave strengthening can shorten the ion exchange time by 40%-60%.

[0013] Preferably, in step (1), the glass is aluminosilicate glass, which comprises the following components by mass percentage: SiO2: 62.8%-71.7%, Al2O3: 8.7%-17%, Na2O: 2%-7%, K2O: 2.3%-6%, MgO: 1.5%-4%, CaO: 2.2%-4.8%, B2O3: 1.2%-3.8%, P2O5: 1%-3%, TiO2: 0.2%-1.4%, ZrO2: 0.2%-1%, CeO2: 0.1%-1%, and SrO: 0.05%-0.6%.

[0014] This invention strengthens aluminosilicate glass by forming a dense compressive stress layer on its surface, resulting in a reinforced glass with a surface compressive stress greater than 900 MPa, a stress layer depth greater than 50 μm, a light transmittance greater than 92%, and a haze of less than 0.2%. This glass exhibits excellent mechanical properties, including high surface hardness, toughness, scratch resistance, and drop resistance.

[0015] Preferably, the aluminosilicate glass comprises the following components by mass percentage: SiO2: 63.6%-71.2%, Al2O3: 9.2%-16.1%, Na2O: 2.8%-5.6%, K2O: 2.5%-5.1%, MgO: 2%-3%, CaO: 2%-4%, B2O3: 1.5%-3.1%, P2O5: 1.2%-2.4%, TiO2: 0.3%-1.2%, ZrO2: 0.3%-0.9%, CeO2: 0.2%-0.8%, and SrO: 0.1%-0.5%.

[0016] The reasons for limiting the composition of aluminosilicate glass to the above range are explained below:

[0017] SiO2 is the glass network forger, determining the basic structure, chemical stability, and light transmittance of the glass. When the SiO2 content is below 58%, the glass network structure is loose, and the mechanical strength and chemical stability decrease; when the SiO2 content is above 75%, the melting temperature increases, energy consumption increases, glass brittleness increases, and processing difficulty increases. Therefore, the SiO2 content affects the overall properties of the glass, and the SiO2 content is limited to 62.8%-71.7%, with a preferred content of 59%-65%.

[0018] Al₂O₃ can enhance the ion exchange rate in chemical strengthening, thereby improving the hardness and mechanical strength of glass and strengthening its chemical stability. When the Al₂O₃ content is below 8%, ion exchange is not conducive, resulting in glass products with poor stability and mechanical strength, making it difficult to meet the requirements of practical applications. When the Al₂O₃ content is above 22%, it increases the viscosity and melting temperature of the system, affecting the strengthening of irregularly shaped glass. Therefore, the Al₂O₃ content is limited to 8.7%-17%, with a preferred content of 9.2%-16.1%.

[0019] Na₂O is an essential component for forming the surface compressive stress layer through ion exchange, playing a role in both suppressing the decrease in CS (compressive stress) and deepening DOL (dilatational stress layer). When the Na₂O content is below 1.5%, the ion exchange performance is poor, and the strengthening effect is weak. When the Na₂O content is above 8%, the coefficient of thermal expansion of the product increases, and the thermal shock resistance and thermal stability decrease. Therefore, the Na₂O content is limited to 2%-7%, preferably 2.8%-5.6%.

[0020] K₂O can improve the melting properties of aluminosilicate glass. K₂O and Na₂O can form a mixed alkali effect, which can reduce the high-temperature viscosity of aluminosilicate glass. When the K₂O content is below 1.5%, the stress layer depth of the K-Na ion exchange layer formed in the chemically strengthened aluminosilicate glass is very shallow, which is not conducive to the migration of K⁺ ions to the inner layer during ion exchange. When the K₂O content is above 7%, the network structure of aluminosilicate glass deteriorates, the stability of thermal properties decreases, and the weather resistance worsens. Therefore, the K₂O content is limited to 2.3%-6%, preferably 2.5%-5.1%.

[0021] MgO is an outer layer of the glass network. Introducing a certain amount can promote glass melting, lower the melting temperature, reduce high-temperature viscosity, improve meltability, facilitate post-processing of the strengthened glass, and increase hydrolysis resistance and durability. When the MgO content is below 1%, the effect of lowering the glass melting temperature is not significant. When the MgO content is above 6%, it leads to easy crystallization of the glass, an excessively high coefficient of thermal expansion, poor melt uniformity, and decreased thermal shock resistance. Therefore, the MgO content is limited to 1.5%-4%, preferably 2%-3%.

[0022] CaO is a component that reduces the high-temperature viscosity of glass, provides chemical stability, promotes glass melting and formability, and also increases the strain point or tensile modulus of elasticity of glass. When the CaO content is below 1%, the effect of reducing the high-temperature viscosity of glass is not achieved. When the CaO content exceeds 6%, the ion exchange performance deteriorates, the strengthening effect is weak, and the deterioration resistance of the glass is worsened. Therefore, the CaO content is limited to 2%-4.8%, preferably 2.2%-4%.

[0023] B₂O₃ is mainly used to lower the melting temperature of glass, accelerate its melting and refining, improve its gloss, enhance its chemical stability, and improve its mechanical properties. When the B₂O₃ content is below 0.5%, the glass is prone to phase separation and has poor homogeneity. When the B₂O₃ content is above 5%, it reduces the chemical stability of the strengthened glass and weakens the ion exchange effect. Therefore, the B₂O₃ content is limited to 1.2%-3.8%, with a preferred content of 1.5%-3.1%.

[0024] P2O5 is used to accelerate the ion exchange rate of glass and can also lower the melting temperature of glass. P2O5 forms a network of interconnected [PO4] tetrahedra, and this network structure is layered, with the layers linked by van der Waals forces. When the P2O5 content is below 0.5%, the uniformity of the glass melt is poor, and the effect of reducing high-temperature viscosity is minimal; when the P2O5 content is above 4%, the chemical stability of the glass decreases, and the coefficient of thermal expansion increases. Therefore, its content is limited to 1%-3%, preferably 1.2%-2.4%.

[0025] TiO2 can improve the acid and alkali corrosion resistance of glass, especially in high-temperature and high-humidity environments, extending its service life. It can also reduce the high-temperature viscosity of the glass melt, improving processing performance. Simultaneously, as a microwave absorbing material, TiO2 can shorten the glass's devitrification time. When the TiO2 content is below 0.2%, the microwave absorption effect of the glass is not significant, and its effect on reducing the high-temperature viscosity of the glass melt is limited; when the TiO2 content exceeds 2%, the glass's devitrification resistance deteriorates. Therefore, the TiO2 content is limited to 0.2%-1.4%, with a preferred content of 0.3%-1.2%.

[0026] ZrO2 can significantly improve the hardness and scratch resistance of glass, inhibit crack propagation, and enhance its chemical stability. When the ZrO2 content is below 0.1%, the improvement in hardness and scratch resistance is not significant. When the ZrO2 content is above 2%, the softening temperature of the glass increases, making it more difficult to mold. Therefore, the ZrO2 content is limited to 0.2%-1%, with a preferred content of 0.3%-0.9%.

[0027] CeO2 can enhance the depth and intensity of surface compressive stress by regulating the vacancy concentration in the glass network structure, thereby promoting the migration efficiency of alkali metal ions. It can also absorb ultraviolet light, improving radiation resistance, and act as a clarifying agent to improve glass uniformity. However, a CeO2 content higher than 1.5% introduces color difference and reduces light transmittance. Therefore, the CeO2 content is limited to 0.1%-1%, preferably 0.2%-0.8%.

[0028] SrO can reduce the high-temperature viscosity and softening temperature of glass, facilitating post-processing of strengthened glass. It also provides chemical stability, promotes glass melting and forming, reduces phase separation tendency, improves glass homogeneity, and lowers tin penetration. However, when the SrO content exceeds 1%, it increases cost and reduces surface compressive stress. Therefore, the SrO content is limited to 0.05%-0.6%, preferably 0.1%-0.5%.

[0029] Preferably, the composition of the aluminosilicate glass satisfies the following relationship: 0.09 ≤ (Na₂O + K₂O) / SiO₂ ≤ 0.18. Na₂O and K₂O, as network modifiers, directly affect the glass's melting characteristics, ion exchange efficiency, and network density. When the (Na₂O + K₂O) / SiO₂ ratio is below 0.07, the glass network over-polymerizes due to insufficient alkali metals, resulting in excessively high melt viscosity and uneven thickness during float glass forming. Simultaneously, the Na₂O content in chemical strengthening... + / K + The ion exchange rate decreases significantly, leading to a deterioration in drop resistance. When the (Na₂O+K₂O) / SiO₂ ratio exceeds 0.21, excessive alkali metals disrupt the stability of the aluminum-silicon network, reducing the glass's water resistance. Furthermore, the excessive internal tensile stress after ion exchange can easily induce spontaneous breakage. Therefore, the (Na₂O+K₂O) / SiO₂ ratio needs to be limited to 0.09-0.18 to balance melting process performance, enhanced properties, and long-term reliability.

[0030] Preferably, the composition of the aluminosilicate glass satisfies the following relationship: 0.04 ≤ (P2O5 + B2O3) / SiO2 ≤ 0.07. P2O5 and B2O3 act as network intermediates, synergistically regulating the openness of the glass structure and ion migration channels. When the (P2O5 + B2O3) / SiO2 ratio is below 0.03, the network becomes excessively dense, hindering K+ ion migration. + / Na + Ion diffusion is impaired, leading to increased glass brittleness. Simultaneously, the high high-temperature viscosity of the melt makes homogenization and drawing difficult. When the (P₂O₅+B₂O₃) / SiO₂ ratio exceeds 0.08, excess B₂O₃ deteriorates acid resistance, P₂O₅ enrichment induces phase separation, resulting in decreased light transmittance and uneven stress distribution after chemical strengthening. Therefore, the (P₂O₅+B₂O₃) / SiO₂ ratio needs to be precisely limited to 0.04-0.07 to optimize the ion exchange kinetic rate.

[0031] Preferably, the composition of the aluminosilicate glass satisfies the following relationship: 0.01 ≤ (SrO + ZrO2 + CeO2 + TiO2) / (SiO2 + Al2O3) ≤ 0.06. SrO, ZrO2, CeO2, and TiO2 act as functional additives, synergistically improving the glass's thermal compatibility, surface hardness, and UV protection. When the ratio of (SrO + ZrO2 + CeO2 + TiO2) / (SiO2 + Al2O3) is less than 0.01, the functional effect is insufficient, the coefficient of thermal expansion is high, the Vickers hardness is low, scratch resistance is poor, and the glass is prone to aging. When the ratio of (SrO + ZrO2 + CeO2 + TiO2) / (SiO2 + Al2O3) exceeds 0.06, the chemical stability is low, and crystallization is likely to occur. Therefore, (SrO+ZrO2+CeO2+TiO2) / (SiO2+Al2O3) needs to be limited to 0.01-0.06.

[0032] Preferably, the composition of the aluminosilicate glass satisfies the following relationship: 0.6% ≤ CeO2 + TiO2 ≤ 1.8%. The combined use of CeO2 and TiO2 can balance the redox environment and nucleation efficiency. CeO2 inhibits Fe 2+ Color centers are caused by impurities, while TiO2 promotes microcrystallization; together, they synergistically improve the light transmittance and mechanical strength of the glass. As functional additives, CeO2 and TiO2 require precise control to balance optical performance and mechanical enhancement. When the CeO2+TiO2 content is below 0.5%, the glass's resistance to microcrack propagation is insufficient, and its ultraviolet shielding efficiency is low, failing to meet the needs of protecting users' eyes. When the CeO2+TiO2 content exceeds 2%, it significantly increases the glass's brittleness; its high refractive index leads to deterioration in light transmittance and may cause light scattering haze. Therefore, the CeO2+TiO2 content needs to be limited to 0.6%-1.8% to achieve functional optimization and risk mitigation.

[0033] The beneficial effects of the present invention are as follows: The strengthening process of the present invention uses microwave-assisted strengthening of glass. Microwave penetrating heating reduces the temperature difference between the surface and the interior, which can avoid microcracks caused by local overheating, thereby improving the uniformity of the ion exchange layer. It is suitable for strengthening various irregularly shaped glasses. Microwaves act directly on the reactants, which can shorten the ion exchange time by 40%-60%, reduce energy consumption, reduce costs, and also deepen the stress layer.

[0034] The strengthening process of this invention strengthens aluminosilicate glass, forming a dense compressive stress layer on the surface of the glass. This results in a strengthened glass with a surface compressive stress greater than 900 MPa, a stress layer depth greater than 50 μm, a light transmittance greater than 92%, and a haze less than 0.2%. The glass exhibits excellent mechanical properties, as well as high surface hardness, toughness, scratch resistance, and drop resistance. Detailed Implementation

[0035] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to embodiments. The content mentioned in the embodiments is not intended to limit the present invention.

[0036] Example 1

[0037] A microwave-assisted glass strengthening process includes the following steps:

[0038] (1) Preheating stage: Preheat the glass with microwave to 300°C for 60 minutes;

[0039] (2) Shallow exchange stage: The glass is placed in the first molten salt and strengthened at 390°C for 2 hours, while low-frequency microwave-assisted strengthening is used at the same time.

[0040] (3) Deep exchange stage: The glass is placed in the second molten salt and strengthened at 420℃ for 4 hours, while high-frequency microwave assisted strengthening is used.

[0041] In step (2), the microwave frequency is 2.1 GHz and the power density is 0.5 W / cm². 3 The first molten salt comprises the following raw materials by weight percentage: KNO3: 64%, NaNO3: 34%, and NaOH: 2%.

[0042] In step (3), the microwave frequency is 3.9 GHz and the power density is 1.2 W / cm². 3 The second molten salt comprises the following raw materials in weight percentages: KNO3: 68%, NaNO3: 24%, NaOH: 3%, KOH: 2%, and NaHCO3: 3%.

[0043] In step (1), the glass is aluminosilicate glass, which comprises the following components by mass percentage: SiO2: 71.2%, Al2O2: 9.2%, Na2O: 5.6%, K2O: 2.5%, MgO: 3%, CaO: 2.4%, B2O3: 3.1%, P2O5: 1.2%, TiO2: 1.2%, ZrO2: 0.3%, CeO2: 0.2%, and SrO: 0.1%.

[0044] Example 2

[0045] A microwave-assisted glass strengthening process includes the following steps:

[0046] (1) Preheating stage: Preheat the glass with microwave to 325°C for 45 minutes;

[0047] (2) Shallow exchange stage: The glass is placed in the first molten salt and strengthened at 400℃ for 1.5h, while low-frequency microwave-assisted strengthening is used at the same time;

[0048] (3) Deep exchange stage: The glass is placed in the second molten salt and strengthened at 425℃ for 3.5h, while high-frequency microwave assisted strengthening is used.

[0049] In step (2), the microwave frequency is 2.45 GHz and the power density is 1.2 W / cm². 3 The first molten salt comprises the following raw materials in weight percentages: KNO3: 70%, NaNO3: 27%, and NaOH: 3%.

[0050] In step (3), the microwave frequency is 5 GHz and the power density is 2 W / cm². 3 The second molten salt comprises the following raw materials in weight percentages: KNO3: 73.5%, NaNO3: 20%, NaOH: 2%, KOH: 2.5%, and NaHCO3: 2%.

[0051] In step (1), the glass is aluminosilicate glass, which comprises the following components by mass percentage: SiO2: 67.4%, Al2O3: 14.1%, Na2O: 4.2%, K2O: 3.3%, MgO: 2.5%, CaO: 2.2%, B2O3: 2.3%, P2O5: 1.8%, TiO2: 0.8%, ZrO2: 0.6%, CeO2: 0.5%, and SrO: 0.3%.

[0052] Example 3

[0053] A microwave-assisted glass strengthening process includes the following steps:

[0054] (1) Preheating stage: Preheat the glass with microwave to 350°C for 30 minutes;

[0055] (2) Shallow exchange stage: The glass is placed in the first molten salt and strengthened at 410°C for 1 hour, while low-frequency microwave-assisted strengthening is used at the same time.

[0056] (3) Deep exchange stage: The glass is placed in the second molten salt and strengthened at 430℃ for 3 hours, while high-frequency microwave assisted strengthening is used.

[0057] In step (2), the microwave frequency is 2.8 GHz and the power density is 2 W / cm². 3 The first molten salt comprises the following raw materials by weight percentage: KNO3: 76%, NaNO3: 20%, and NaOH: 4%.

[0058] In step (3), the microwave frequency is 6.1 GHz and the power density is 3 W / cm². 3The second molten salt comprises the following raw materials in weight percentages: KNO3: 79%, NaNO3: 16%, NaOH: 1%, KOH: 3%, and NaHCO3: 1%.

[0059] In step (1), the glass is aluminosilicate glass, which comprises the following components by mass percentage: SiO2: 63.6%, Al2O3: 16.1%, Na2O: 2.8%, K2O: 5.1%, MgO: 2%, CaO: 4%, B2O3: 1.5%, P2O5: 2.4%, TiO2: 0.3%, ZrO2: 0.9%, CeO2: 0.8%, and SrO: 0.5%.

[0060] Comparative Examples 1-6:

[0061] The components of Comparative Examples 1-6 are shown in the table below, and the strengthening process is the same as that of Example 2.

[0062] Components / % Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 <![CDATA[SiO2]]> 67.3 70.5 68.9 66.2 69.8 64.7 <![CDATA[Al2O3]]> 14.5 12.1 13.8 15.4 11.6 16 <![CDATA[Na2O]]> 4.8 3.5 4.2 5.2 4.5 5.5 <![CDATA[K2O]]> 4.5 4.8 4.6 3.8 4.1 4.3 MgO 2.7 2.3 2.5 2.9 2.4 2.6 CaO 3.2 3.6 3.4 3.5 3.8 3.9 <![CDATA[B2O3]]> 2.4 2.1 2.3 2 2.5 1.8 <![CDATA[P2O5]]> 1.6 1.7 1.7 1.5 1.9 1.7 <![CDATA[TiO2]]> - 0.9 - - - - <![CDATA[ZrO2]]> - - 0.7 - - 0.8 <![CDATA[CeO2]]> - - - 0.5 - - SrO - - - - 0.4 0.3

[0063] Comparative Example 7

[0064] The difference between Comparative Example 7 and Example 2 above is that microwave-assisted strengthening is not used in steps (1)-(3).

[0065] The performance tests of the tempered glass prepared in Examples 1-3 and Comparative Examples 1-7 are shown in the table below.

[0066]

[0067] As can be seen from the table above, the strengthening process of the present invention uses microwave-assisted glass strengthening. Microwave penetrating heating reduces the temperature difference between the surface and the interior, which can avoid microcracks caused by local overheating, thereby improving the uniformity of the ion exchange layer. It is suitable for strengthening various irregularly shaped glasses. Microwaves act directly on the reactants, which can shorten the ion exchange time by 40%-60%, reduce energy consumption, reduce costs, and also deepen the stress layer.

[0068] The strengthening process of this invention strengthens aluminosilicate glass, forming a dense compressive stress layer on the surface of the glass. This results in a strengthened glass with a surface compressive stress greater than 900 MPa, a stress layer depth greater than 50 μm, a light transmittance greater than 92%, and a haze less than 0.2%. The glass exhibits excellent mechanical properties, as well as high surface hardness, toughness, scratch resistance, and drop resistance.

[0069] The above embodiments are preferred implementations of the present invention. In addition, the present invention can be implemented in other ways. Any obvious substitutions without departing from the concept of the present invention are within the protection scope of the present invention.

Claims

1. A microwave-assisted glass strengthening process characterized by: The method comprises the following steps: (1) a preheating stage: the glass is preheated by microwave to 300-350℃ for 30-60min; (2) a shallow layer exchange stage: the glass is put into the first molten salt and strengthened at 390-410℃ for 1-2h while being assisted by low-frequency microwave; (3) a deep layer exchange stage: the glass is put into the second molten salt and strengthened at 420-430℃ for 3-4h while being assisted by high-frequency microwave; In the step (2), the first molten salt comprises the following raw materials in percentage by weight: KNO3: 64%-76%, NaNO3: 20%-34% and NaOH: 2%-4%; In the step (3), the second molten salt comprises the following raw materials in percentage by weight: KNO3: 68%-79%, NaNO3: 16%-24%, NaOH: 1%-3%, KOH: 2%-3% and NaHCO3: 1%-3%.

2. A microwave assisted glass strengthening process according to claim 1, wherein: In the step (2), the microwave frequency is 2.1-2.8GHz and the power density is 0.5-2W / cm³; in the step (3), the microwave frequency is 3.9-6.1GHz and the power density is 1.2-3W / cm³.

3. The microwave assisted glass strengthening process of claim 1, wherein: In the step (1), the glass is an aluminosilicate glass comprising the following components in percentage by mass: SiO2: 62.8%-71.7%, Al2O3: 8.7%-17%, Na2O: 2%-7%, K2O: 2.3%-6%, MgO: 1.5%-4%, CaO: 2%-4.8%, B2O3: 1.2%-3.8%, P2O5: 1%-3%, TiO2: 0.2%-1.4%, ZrO2: 0.2%-1%, CeO2: 0.1%-1% and SrO: 0.05%-0.6%.

4. A microwave assisted glass strengthening process as claimed in claim 3, wherein: The aluminosilicate glass comprises the following components in percentage by mass: SiO2: 63.6%-71.2%, Al2O3: 9.2%-16.1%, Na2O: 2.8%-5.6%, K2O: 2.5%-5.1%, MgO: 2%-3%, CaO: 2.2%-4%, B2O3: 1.5%-3.1%, P2O5: 1.2%-2.4%, TiO2: 0.3%-1.2%, ZrO2: 0.3%-0.9%, CeO2: 0.2%-0.8% and SrO: 0.1%-0.5%.

5. A microwave assisted glass strengthening process as claimed in claim 3, wherein: The components of the aluminosilicate glass satisfy the following relationship: 0.09≤(Na2O+K2O) / SiO2≤0.

18.

6. A microwave assisted glass strengthening process as claimed in claim 3, wherein: The components of the aluminosilicate glass satisfy the following relationship: 0.04≤(P2O5+B2O3) / SiO2≤0.

07.

7. A microwave assisted glass strengthening process as claimed in claim 3, wherein: The components of the aluminosilicate glass satisfy the following relationship: 0.01≤(SrO+ZrO2+CeO2+TiO2) / (SiO2+Al2O3)≤0.

06.

8. The microwave assisted glass strengthening process of claim 3, wherein: The components of the aluminosilicate glass satisfy the following relationship: 0.6%≤CeO2+TiO2≤1.8%.

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