Microwave-assisted glass strengthening process

Abstract

The invention relates to the technical field of glass strengthening, in particular to a microwave-assisted glass strengthening process which comprises the following steps: (1) a preheating stage: preheating glass to 300-350 DEG C for 30-60 minutes by adopting microwaves; (2) superficial layer exchange stage: putting the glass into first fused salt, strengthening for 1-2 hours at the temperature of 390-410 DEG C, and simultaneously adopting low-frequency microwave to assist in strengthening; and (3) a deep exchange stage: putting the glass into second fused salt, strengthening at the temperature of 420-430 DEG C for 3-4 hours, and meanwhile, adopting high-frequency microwaves to assist in strengthening. According to the method, the temperature difference between the surface and the interior is reduced by adopting microwave-assisted glass strengthening and microwave penetrability heating, and microcracks caused by local overheating can be avoided, so that the uniformity of an ion exchange layer is improved, and the method is suitable for strengthening various special-shaped glass; microwaves directly act on reactants, so that the ion exchange time can be shortened by 40-60%, the energy consumption is reduced, and the efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of glass strengthening, and particularly relates to a microwave-assisted glass strengthening process. Background Art

[0002] Chemically strengthened glass products are widely used in electronic fields such as mobile phones, watches, computers, and touch panels due to their good light transmittance, excellent touch and feel. With the continuous improvement of the requirements for the bending resistance and hardness of strengthened glass, the glass strengthening process has gradually become more complex. Currently, the glass processing industry generally requires strengthened glass products to have high DOL values and high CS values, and a single strengthening generally cannot meet both of these values simultaneously, thus unable to meet the user's requirements for product performance. In order to further improve the DOL value and CS value of strengthened glass to enhance the bending resistance and scratch resistance of strengthened glass, a two-step strengthening process is generally used to process the glass, thereby better improving the product life.

[0003] The Chinese invention patent with the application number 201911217898.7 discloses a glass strengthening process that can reduce warping and dimensional expansion. This process includes the first strengthening and the second strengthening: (1) The first strengthening: Put the glass into a molten salt containing low-concentration potassium nitrate and strengthen it at a temperature of 375 - 385 °C for 9 - 11 h; (2) The second strengthening: Put the glass after the first strengthening into a molten salt containing high-concentration potassium nitrate and strengthen it at a temperature of 405 - 415 °C for 1.5 - 2.5 h; The strengthening process of this invention adopts a two-step method. In the first step, a suitable stress layer compression depth is obtained by slowly strengthening in a molten salt containing low-concentration potassium nitrate. In the second step, a suitable surface compressive stress of the glass is obtained by quickly strengthening in a molten salt containing high-concentration potassium nitrate, which can reduce glass warping and avoid dimensional expansion during glass strengthening. The steps are simple and the operation control is convenient. However, the two-step strengthening process for processing glass has a long strengthening time, high energy consumption, and high cost. The traditional heating method conducts heat from the outside to the inside, which easily causes a large temperature difference between the glass surface and the inside, leading to local stress concentration or microcracks, affecting the yield of 3D curved glass or special-shaped glass covers. Summary of the Invention

[0004] In order to overcome the disadvantages and deficiencies existing in the prior art, the purpose of the present invention is to provide a microwave-assisted glass strengthening process. This strengthening process uses microwave assistance for strengthening, which not only ensures the glass strengthening effect but also shortens the glass strengthening time, can reduce energy consumption, reduce costs, improve efficiency, and at the same time, the microwave uniformly heats the inside and outside of the glass, reduces the temperature gradient, avoids microcracks, and is applicable to the strengthening of various special-shaped glasses.

[0005] The purpose of the present invention is achieved through the following technical solutions: A microwave-assisted glass strengthening process includes the following steps:

[0006] (1) Preheating stage: The glass is preheated by microwave to 300 - 350 °C and preheated for 30 - 60 min;

[0007] (2) Shallow exchange stage: The glass is placed in the first molten salt and strengthened at a temperature of 390 - 410 °C for 1 - 2 h, while assisted by low-frequency microwave for strengthening;

[0008] (3) Deep exchange stage: The glass is placed in the second molten salt and strengthened at a temperature of 420 - 430 °C for 3 - 4 h, while assisted by high-frequency microwave for strengthening.

[0009] The strengthening process of the present invention strengthens the glass by using microwave assistance. The microwave penetrative heating reduces the temperature difference between the surface and the interior, and can avoid microcracks caused by local overheating, thereby improving the uniformity of the ion exchange layer and being applicable to 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, lower costs, and can also deepen the stress layer depth.

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

[0011] Preferably, in the step (3), the second molten salt comprises raw materials in the following weight percentages: KNO3: 68% - 79%, NaNO3: 16% - 24%, NaOH: 1% - 3%, KOH: 2% - 3%, and NaHCO3: 1% - 3%. NaOH and KOH can ionize OH - , OH - As a polar molecule under the action of microwave, it can improve the ion exchange rate of Na + / K + ions between the molten salt and the glass, shorten the strengthening time, and deepen the depth of the compressive stress layer. The addition of NaHCO3 can prevent the glass surface from being corroded by excessive NaOH and KOH.

[0012] Preferably, in the step (2), the microwave frequency is 2.1 - 2.8 Hz, and the power density is 0.5 - 2 W / cm 3 ; in the step (3), the microwave frequency is 3.9 - 6.1 Hz, and the power density is 1.2 - 3 W / cm 3Microwaves can increase the ion exchange rate between glass and molten salt and shorten the glass strengthening time. Compared with the traditional strengthening time, after introducing microwave strengthening, the ion exchange time can be shortened by 40%-60%.

[0013] Preferably, in the step (1), the glass is aluminosilicate glass, and the aluminosilicate glass comprises the following components in mass percentages: 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] By strengthening the aluminosilicate glass, the present invention can form a dense compressive stress layer on the surface of the aluminosilicate glass, obtaining strengthened glass with a surface compressive stress greater than 900 MPa, a stress layer depth exceeding 50 μm, a light transmittance greater than 92%, and a haze less than 0.2%. It has excellent mechanical properties, high surface hardness, toughness, scratch resistance, and drop resistance.

[0015] Preferably, the aluminosilicate glass comprises the following components in mass percentages: 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%-2%, 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 the aluminosilicate glass within the above range are as follows:

[0017] SiO2 is a glass network former, which determines the basic structure, chemical stability, and light transmittance of the glass. When the content of SiO2 is lower than 58%, the glass network structure is loose, and the mechanical strength and chemical stability decrease; when the content of SiO2 is higher than 75%, the melting temperature increases, the energy consumption increases, the brittleness of the glass increases, and the processing difficulty rises. Therefore, the content of SiO2 affects the overall performance of the glass, and the content of SiO2 is limited to 62.8%-71.7%, and the preferred content is 59%-65%.

[0018] Al2O3 can improve the ion exchange rate in chemical strengthening, enhance the glass hardness and mechanical strength, and strengthen the chemical stability of the glass. When the content of Al2O3 is less than 8%, it is not conducive to ion exchange, and the stability and mechanical strength of the obtained glass products are both poor, making it difficult to meet the requirements of practical applications. When the content of Al2O3 is higher than 22%, the viscosity and melting temperature of the system increase, affecting the strengthening of profiled glass. Therefore, the content of Al2O3 is limited to 8.7% - 17%, and the preferred content is 9.2% - 16.1%.

[0019] Na2O is a necessary component for forming a surface compressive stress layer through ion exchange, and it has the effect of deepening DOL while suppressing the decrease of CS. When the content of Na2O is less than 1.5%, the ion exchange performance is poor and the strengthening effect is weak. When the content of Na2O is higher than 8%, the thermal expansion coefficient of the product increases, and the heat shock resistance and thermal stability decrease. Therefore, the content of Na2O is limited to 2% - 7%, and the preferred content is 2.8% - 5.6%.

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

[0021] MgO is an external component of the glass network. Introducing a certain amount can promote the melting of the glass, reduce the melting temperature of the glass, and can also reduce the high-temperature viscosity of the glass, improve the meltability, facilitate the post-processing of the strengthened glass, and at the same time increase the hydrolysis resistance and improve the durability. When the content of MgO is less than 1%, the effect of reducing the melting temperature of the glass is not obvious. When the content of MgO is higher than 6%, it will cause the glass to be prone to crystallization and have too high a coefficient of thermal expansion, poor melting uniformity, and a decrease in thermal shock resistance. Therefore, the content of MgO is limited to 1.5% - 4%, and the preferred content is 2% - 3%.

[0022] CaO is a component that reduces the high-temperature viscosity of the glass, provides chemical stability, promotes the melting or formability of the glass, and also has the effect of increasing the strain point or tensile elastic modulus of the glass. When the content of CaO is less than 1%, the effect of the high-temperature viscosity of the glass cannot be achieved. When the content of CaO exceeds 6%, the ion exchange performance deteriorates, the strengthening effect is weak, and the devitrification resistance of the glass deteriorates. Therefore, the content of CaO is limited to 2% - 4.8%, and the preferred content is 2.2% - 4%.

[0023] B2O3 is mainly used to reduce the melting temperature of glass, which can accelerate the melting and clarification of glass, improve the luster of glass, enhance the chemical stability of glass, and also improve the mechanical properties of glass. When the content of B2O3 is less than 0.5%, the glass is prone to phase separation and has poor uniformity. When the content of B2O3 is higher than 5%, it will reduce the chemical stability of the strengthened glass and weaken the ion exchange effect. Therefore, the content of B2O3 is limited to 1.2% - 3.8%, and the preferred content is 1.5% - 3.1%.

[0024] P2O5 is used to accelerate the glass ion exchange rate. In addition, it can also reduce the melting temperature of glass. P2O5 forms a network by connecting [PO4] tetrahedrons with each other. The network structure formed by P2O5 belongs to a layered structure, and the layers are connected by van der Waals forces. When the content of P2O5 is less than 0.5%, the uniformity of the glass melt is poor, and the effect of reducing the high-temperature viscosity is poor; when the content of P2O5 is higher than 4%, the chemical stability of the glass decreases and the thermal expansion coefficient increases. Therefore, its content is limited to 1% - 3%, and the preferred content is 1.2% - 2.4%.

[0025] TiO2 can improve the acid and alkali corrosion resistance of glass, especially in high-temperature and high-humidity environments, extend the service life, and can also reduce the high-temperature viscosity of the glass melt and improve the processing performance. At the same time, as a wave-absorbing material, TiO2 can shorten the heating time of the glass. When the content of TiO2 is less than 0.2%, the wave-absorbing effect of the glass is not obvious, and the effect of reducing the high-temperature viscosity of the glass melt is limited; when the content of TiO2 exceeds 2%, the devitrification resistance of the glass becomes poor. Therefore, the content of TiO2 is limited to 0.2% - 1.4%, and the preferred content is 0.3% - 1.2%.

[0026] ZrO2 can significantly improve the hardness and scratch resistance of glass, inhibit crack propagation, and enhance the chemical stability of glass. When the content of ZrO2 is less than 0.1%, the improvement effect on the glass hardness and scratch resistance is not obvious. When the content of ZrO2 is higher than 2%, the softening temperature of the glass will increase, making it difficult to shape the glass. Therefore, the content of ZrO2 is limited to 0.2% - 1%, and the preferred content is 0.3% - 0.9%.

[0027] CeO2 can promote the migration efficiency of alkali metal ions by adjusting the vacancy concentration in the glass network structure, thereby enhancing the depth and strength of the surface compressive stress. At the same time, it can also absorb ultraviolet rays, improve the radiation resistance, and can be used as a clarifying agent to improve the uniformity of the glass. When the content of CeO2 is higher than 1.5%, it will introduce color difference and reduce the light transmittance. Therefore, the content of CeO2 is limited to 0.1% - 1%, and the preferred content is 0.2% - 0.8%.

[0028] SrO can reduce the high-temperature viscosity and softening temperature of the glass, facilitating the post-processing of the strengthened glass. At the same time, it provides chemical stability, promotes the melting or forming of the glass, can reduce the phase separation tendency, improve the glass uniformity and reduce the tin penetration rate. When the content of SrO is higher than 1%, it will increase the cost and also reduce the surface compressive stress. Therefore, the content of SrO is limited to 0.05%-0.6%, and the preferred content is 0.1%-0.5%.

[0029] Preferably, the components of the aluminosilicate glass satisfy the following relationship: 0.09 ≤ (Na2O + K2O) / SiO2 ≤ 0.18. Na2O and K2O, as network modifiers, directly affect the melting characteristics, ion exchange efficiency and network densification of the glass. When the ratio of (Na2O + K2O) / SiO2 is lower than 0.07, the glass network is over-polymerized due to insufficient alkali metals, and the melt viscosity is too high, resulting in uneven thickness during float forming; at the same time, the Na + / K + ion exchange rate is significantly reduced, and the anti-drop performance deteriorates. When the ratio of (Na2O + K2O) / SiO2 exceeds 0.21, the excessive alkali metals destroy the stability of the aluminosilicate network, the water resistance of the glass decreases, and the internal tensile stress is too large after ion exchange, which is prone to induce spontaneous rupture. Therefore, (Na2O + K2O) / SiO2 needs to be limited to 0.09 - 0.18 to balance the melting process, strengthening performance and long-term reliability.

[0030] Preferably, the components of the aluminosilicate glass satisfy the following relationship: 0.04 ≤ (P2O5 + B2O3) / SiO2 ≤ 0.07. P2O5 and B2O3, as network intermediates, jointly regulate the openness of the glass structure and the ion migration channels. When the ratio of (P2O5 + B2O3) / SiO2 is lower than 0.03, the network densification is excessive, hindering the K + / Na + ion diffusion, and the brittleness of the glass increases. At the same time, the melt viscosity at high temperature is too high, making it difficult to achieve homogeneous drawing; when the ratio of (P2O5 + B2O3) / SiO2 exceeds 0.08, the excessive B2O3 leads to deteriorated acid resistance, P2O5 enrichment causes phase separation, the light transmittance decreases, and the stress distribution is uneven after chemical strengthening. Therefore, (P2O5 + B2O3) / SiO2 needs to be accurately 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 are used as functional additives to synergistically improve the thermal matching, surface hardness and ultraviolet protection ability of the glass. When the ratio of (SrO + ZrO2 + CeO2 + TiO2) / (SiO2 + Al2O3) is lower than 0.01, the functional effect is insufficient, the thermal expansion coefficient is large, the Vickers hardness is low, the 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% ≤ CeO + TiO2 ≤ 1.8%. The combined use of CeO2 and TiO2 can balance the redox environment and nucleation efficiency. CeO2 inhibits the color centers caused by impurities such as Fe 2+ etc., while TiO2 promotes microcrystallization. The two work together to improve the light transmittance and mechanical strength of the glass. As functional additives, CeO2 and TiO2 need to be precisely regulated to balance optical properties and mechanical enhancement. When the content of CeO2 + TiO2 is lower than 0.5%, the glass has insufficient ability to resist the propagation of microcracks and low ultraviolet shielding efficiency, unable to meet the needs of protecting users' eyes. When the content of CeO2 + TiO2 exceeds 2%, it will significantly increase the brittleness of the glass. Its high refractive index will lead to deterioration of light transmittance and may cause light scattering haze. Therefore, the content of CeO2 + TiO2 needs to be limited to 0.6% - 1.8% to achieve functional optimization and risk avoidance.

[0033] The beneficial effects of the present invention are as follows: The strengthening process of the present invention uses microwave-assisted glass strengthening. The microwave penetrative 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 and being applicable to 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, lower costs, and also deepen the stress layer depth.

[0034] The strengthening process of the present invention can form a dense compressive stress layer on the surface of the aluminosilicate glass through strengthening treatment, obtaining strengthened glass with a surface compressive stress greater than 900 MPa, a stress layer depth exceeding 50 μm, a light transmittance greater than 92%, and a haze less than 0.2%. It has excellent mechanical properties, with high surface hardness, toughness, scratch resistance and drop resistance. Detailed implementation manners

[0035] For the convenience of those skilled in the art, the present invention will be further described below in conjunction with embodiments. The content mentioned in the embodiments does not limit the present invention.

[0036] Example 1

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

[0038] (1) Preheating stage: The glass is preheated by microwave to 300 °C and preheated for 60 min;

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

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

[0041] In step (2), the microwave frequency is 2.1 Hz and the power density is 0.5 W / cm 3 , and the first molten salt includes raw materials in the following weight percentages: KNO3: 64%, NaNO3: 34%, and NaOH: 2%.

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

[0043] In step (1), the glass is aluminosilicate glass, and the aluminosilicate glass includes components in the following mass percentages: SiO2: 71.2%, Al2O3: 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: The glass is preheated by microwave to 325 °C and preheated for 45 min;

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

[0048] (3) Deep exchange stage: Put the glass into the second molten salt and strengthen it at 425 °C for 3.5 h, while using high-frequency microwave-assisted strengthening.

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

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

[0051] In step (1), the glass is aluminosilicate glass, and the aluminosilicate glass includes components with the following mass percentages: 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 and preheat for 30 min;

[0055] (2) Shallow exchange stage: Put the glass into the first molten salt and strengthen it at 410 °C for 1 h, while using low-frequency microwave-assisted strengthening;

[0056] (3) Deep exchange stage: Put the glass into the second molten salt and strengthen it at 430 °C for 3 h, while using high-frequency microwave-assisted strengthening.

[0057] In step (2), the microwave frequency is 2.8 Hz and the power density is 2 W / cm 3 , and the first molten salt includes raw materials with the following weight percentages: KNO3: 76%, NaNO3: 20%, and NaOH: 4%.

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

[0059] In step (1), the glass is aluminosilicate glass, and the aluminosilicate glass comprises components in the following mass percentages: 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 following table, and the strengthening process is the same as that of Example 2.

[0062] Component / % 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 the above Example 2 is that microwave-assisted strengthening is not used in steps (1)-(3).

[0065] The performance tests of the strengthened glasses prepared in Examples 1-3 and Comparative Examples 1-7 are shown in the following table.

[0066]

[0067] As can be seen from the above table, the strengthening process of the present invention uses microwave-assisted strengthening of glass. The microwave penetrative heating reduces the temperature difference between the surface and the interior, can avoid microcracks caused by local overheating, thereby improving the uniformity of the ion exchange layer, and is applicable to the strengthening of various shaped glasses; the microwave directly acts on the reactants, can shorten the ion exchange time by 40%-60%, reduce energy consumption, lower costs, and can also deepen the stress layer depth.

[0068] The strengthening process of the present invention can form a dense compressive stress layer on the surface of the aluminosilicate glass through strengthening treatment, and obtain strengthened glass with a surface compressive stress greater than 900 MPa, a stress layer depth exceeding 50 μm, a light transmittance greater than 92%, and a haze less than 0.2%. It has excellent mechanical properties, high surface hardness, toughness, scratch resistance and drop resistance.

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

Claims

1. A microwave-assisted glass strengthening process, characterized in that: It includes the following steps: (1) Preheating stage: The glass is preheated by microwave to 300 - 350 °C and preheated for 30 - 60 min. (2) Shallow exchange stage: The glass is put into the first molten salt and strengthened at 390 - 410 °C for 1 - 2 h, and at the same time, low-frequency microwave is used for auxiliary strengthening. (3) Deep exchange stage: The glass is put into the second molten salt and strengthened at 420 - 430 °C for 3 - 4 h, and at the same time, high-frequency microwave is used for auxiliary strengthening.

2. The microwave-assisted glass strengthening process according to claim 1, wherein: In the step (2), the first molten salt includes raw materials with the following weight percentages: KNO3: 64% - 76%, NaNO3: 20% - 34%, and NaOH: 2% - 4%.

3. A microwave-assisted glass strengthening process according to claim 1, characterized in that: In the step (3), the second molten salt includes raw materials with the following weight percentages: KNO3: 68% - 79%, NaNO3: 16% - 24%, NaOH: 1% - 3%, KOH: 2% - 3%, and NaHCO3: 1% - 3%.

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

5. A microwave-assisted glass strengthening process according to claim 1, characterized in that: In the step (1), the glass is aluminosilicate glass, and the aluminosilicate glass includes components with the following mass percentages: 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%.

6. The microwave-assisted glass strengthening process according to claim 5, characterized in that: The aluminosilicate glass includes components with the following mass percentages: 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%.

7. A microwave-assisted glass strengthening process according to claim 5, characterized in that: The components of the aluminosilicate glass satisfy the following relational expression: 0.09 ≤ (Na2O + K2O) / SiO2 ≤ 0.

18.

8. A microwave-assisted glass strengthening process according to claim 5, characterized in that: The components of the aluminosilicate glass satisfy the following relational expression: 0.04 ≤ (P2O5 + B2O3) / SiO2 ≤ 0.

07.

9. A microwave-assisted glass strengthening process according to claim 5, characterized in that: The components of the aluminosilicate glass satisfy the following relational expression: 0.01 ≤ (SrO + ZrO2 + CeO2 + TiO2) / (SiO2 + Al2O3) ≤ 0.

06.

10. A microwave-assisted glass strengthening process according to claim 5, characterized in that: The components of the aluminosilicate glass satisfy the following relational expression: 0.6% ≤ CeO + TiO2 ≤ 1.8%.

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