Production process for improving falling ball impact resistance of high-crystallinity glass ceramics

Abstract

The invention relates to the technical field of glass processing, in particular to a production process for improving falling ball impact resistance of high-crystallinity microcrystalline glass, according to the production process, through high-temperature long-time preheating, the interval of bridge oxygen bond ions is increased, and channels are enlarged, so that sodium-lithium exchange and potassium-sodium exchange are more sufficient; pure sodium molten salt is adopted for primary strengthening, pure potassium molten salt is adopted for secondary strengthening, potassium ions with large diameters are densely stacked on the surface, the larger the diameters of the ions are, the larger the bond energy is, the more compact the distribution of the potassium ions is, and the larger the pressure stress CS is; the surface is treated in an optical polishing mode after strengthening, micro-cracks are repaired, and the obtained high-crystallinity glass ceramic is excellent in falling ball impact resistance.

Description

Technical Field

[0001] The invention relates to the technical field of glass processing, and in particular to a production process for improving the falling ball impact resistance of high-crystallization microcrystalline glass. Background Art

[0002] High-crystallization microcrystalline glass has significantly improved the anti-drop performance of the entire machine, but there is a certain contradiction between the improvement of anti-drop performance and the improvement of anti-falling ball impact performance. The better the anti-drop performance, the worse the anti-falling ball impact performance.

[0003] The drop ball impact resistance of the glass cover is related to (KIC / Y*C)+CS, where KIC is the fracture toughness. Y is the coefficient, C is the width of the microcrack, and CS is the compressive stress on the surface of the product. From the above formula, it can be seen that in order to improve the drop ball impact resistance of the glass cover, the following aspects can be used: 1. The fracture toughness of the glass can be improved, and the raw material components of the glass and the skeleton structure of the glass can be changed. For example, SiO2, Al2O3, GeO2, V2O5, P2O5 and B2O3; because the above oxides are ionic compounds inside, they are composed of ionic bonds, and each ionic bond has a corresponding bond energy, bond length and bond angle. The stronger the bond energy, the shorter the bond length, and the smaller the bond angle, the greater the strength of the hard object to pierce and tear; 2. The higher the compressive stress on the glass surface, the better the drop ball impact resistance; 3. The smaller the microcracks on the glass surface, the greater the energy required for the drop ball impact to tear it open.

[0004] Since the fracture toughness of the glass cover depends on the component design of the raw material itself and cannot be changed, it is necessary to improve the micro-crack width and surface compressive stress of the glass cover. Summary of the invention

[0005] In order to overcome the shortcomings and deficiencies in the prior art, the object of the present invention is to provide a production process for improving the falling ball impact resistance of high-crystallinity glass-ceramics.

[0006] The object of the present invention is achieved by the following technical solution: A production process for improving the anti-falling ball impact performance of high-crystallinity microcrystalline glass, comprising the following steps:

[0007] (1) Primary strengthening: preheat the high crystallinity glass-ceramics at 380-450°C for 20-30 min, then place it in a molten salt of sodium nitrate and strengthen it at 450-490°C for 6-7 h. After dripping salt on the strengthened glass for 4-6 min, transfer it to room temperature for cooling.

[0008] (2) Secondary strengthening: preheat the high crystallinity glass-ceramics at 380-450°C for 20-30 min, then place it in molten potassium nitrate at 370-410°C for 15-25 min, drip salt on the strengthened glass for 4-6 min, and then transfer it to room temperature for cooling;

[0009] (3) Surface polishing: The surface of the strengthened glass is treated with optical polishing to repair micro cracks, thereby obtaining high-crystallinity microcrystalline glass with excellent resistance to falling ball impact.

[0010] The production process principle of the present invention is as follows:

[0011] 1. Improve the compressive stress on the surface of the product: Because glass is formed by a variety of oxide components, oxygen ions act as a bridge inside to bring together non-metallic cations, such as silicon, boron and other cations. There are also metal cations, such as lithium, sodium, etc. These ions act as glass changers; oxygen acts as a bridge, tightly linked together through ionic bonds. The bond energy, bond length and bond angle of ionic bonds in different substances are different. By increasing the chemical replacement of sodium and lithium ions, and then by the chemical replacement of potassium and sodium ions, the surface of the glass cover is densely packed with potassium ions with relatively large diameters. The larger the ion diameter, the greater the bond energy, the denser the potassium ion distribution, and the greater the compressive stress CS. Specifically, the existing process of mixed molten salt strengthening is adjusted to use pure sodium molten salt for primary strengthening and pure potassium molten salt for secondary strengthening, thereby improving sodium-lithium and potassium-sodium replacement.

[0012] 2. Improve the surface compressive stress of the product: Because various ions inside the glass are closely combined together through the bridge effect of oxygen ions. Through high temperature and long-term preheating, the distance between the bridge oxygen bond ions is widened and the channel is enlarged, so that the sodium-lithium exchange and potassium-sodium exchange are more sufficient.

[0013] 3. Reduce the width of micro cracks on the product surface: After strengthening, ion replacement and redistribution of ions will cause micro cracks. The surface can be treated by optical polishing after strengthening to repair the micro cracks.

[0014] Preferably, in step (1), the preheating temperature is 420-450°C and the time is 20-30 minutes. By preheating at high temperature for a long time, the distance between the bridging oxygen bonds is widened and the channel is enlarged, so that the sodium-lithium exchange and the potassium-sodium exchange are more complete.

[0015] Preferably, in step (1), the strengthening temperature is 460° C. and the time is 6.5 hours. By adopting high temperature and long time to carry out strengthening once, the sodium-lithium replacement is improved, and the surface compressive stress of the product is increased.

[0016] Preferably, in step (2), the preheating temperature is 420-450°C and the time is 20-30 minutes. By preheating at high temperature for a long time, the distance between the bridging oxygen bonds is widened and the channel is enlarged, so that the sodium-lithium exchange and the potassium-sodium exchange are more complete.

[0017] Preferably, in step (2), the strengthening temperature is 390° C. and the time is 20 min. By adopting low temperature and short time for secondary strengthening, potassium-sodium substitution is improved, and the surface compressive stress of the product is further increased.

[0018] Another object of the present invention is achieved through the following technical solution: a high-crystallinity glass-ceramic with excellent resistance to falling ball impact, wherein the high-crystallinity glass-ceramic is produced according to the production process described above.

[0019] The beneficial effects of the present invention are as follows: the production process of the present invention uses high-temperature and long-term preheating to increase the distance between the bridging oxygen bond ions and enlarge the channels, so that the sodium-lithium exchange and the potassium-sodium exchange are more sufficient; by using pure sodium molten salt for primary strengthening and pure potassium molten salt for secondary strengthening, potassium ions with relatively large diameters are densely accumulated on the surface, and the larger the ion diameter, the greater the bond energy, the denser the potassium ion distribution, and the greater the compressive stress CS; by treating the surface with an optical polishing method after strengthening, microcracks are repaired, and the obtained high-crystallinity microcrystalline glass has excellent resistance to falling ball impact. DETAILED DESCRIPTION

[0020] In order to facilitate the understanding of those skilled in the art, the present invention is further described below in conjunction with embodiments, and the contents mentioned in the implementation modes are not intended to limit the present invention.

[0021] Example 1

[0022] A production process for improving the ball drop impact resistance of high-crystallization glass-ceramics, comprising the following steps:

[0023] (1) Primary strengthening: preheat the high crystallinity glass-ceramics at 380°C for 20 min, then place it in a molten salt of sodium nitrate and strengthen it at 470°C for 6.5 h. After dripping salt on the strengthened glass for 5 min, transfer it to room temperature for cooling.

[0024] (2) Secondary strengthening: preheat the high crystallinity glass-ceramics at 380°C for 20 min, then place it in a molten salt of potassium nitrate and strengthen it at 390°C for 20 min. After dripping salt on the strengthened glass for 5 min, transfer it to room temperature for cooling.

[0025] (3) Surface polishing: The surface of the strengthened glass is treated with optical polishing to repair micro cracks, thereby obtaining high-crystallinity microcrystalline glass with excellent resistance to falling ball impact.

[0026] A high-crystallinity glass-ceramic with excellent falling ball impact resistance, wherein the high-crystallinity glass-ceramic is produced according to the above-mentioned production process.

[0027] Example 2

[0028] A production process for improving the ball drop impact resistance of high-crystallization glass-ceramics, comprising the following steps:

[0029] (1) Primary strengthening: preheat the high crystallinity glass-ceramics at 420°C for 25 min, then place it in a sodium nitrate molten salt and strengthen it at 470°C for 6.5 h. After dripping salt on the strengthened glass for 5 min, transfer it to room temperature for cooling.

[0030] (2) Secondary strengthening: preheat the high crystallinity glass-ceramics at 420°C for 25 min, then place it in a molten salt of potassium nitrate and strengthen it at 390°C for 20 min. After dripping salt on the strengthened glass for 5 min, transfer it to room temperature for cooling.

[0031] (3) Surface polishing: The surface of the strengthened glass is treated with optical polishing to repair micro cracks, thereby obtaining high-crystallinity microcrystalline glass with excellent resistance to falling ball impact.

[0032] A high-crystallinity glass-ceramic with excellent falling ball impact resistance, wherein the high-crystallinity glass-ceramic is produced according to the above-mentioned production process.

[0033] Example 3

[0034] A production process for improving the ball drop impact resistance of high-crystallization glass-ceramics, comprising the following steps:

[0035] (1) Primary strengthening: preheat the high crystallinity glass-ceramics at 450°C for 30 min, then place it in a sodium nitrate molten salt and strengthen it at 470°C for 6.5 h. After dripping salt on the strengthened glass for 5 min, transfer it to room temperature for cooling.

[0036] (2) Secondary strengthening: preheat the high crystallinity glass-ceramics at 450°C for 30 min, then place it in a molten salt of potassium nitrate and strengthen it at 390°C for 20 min. After dripping salt on the strengthened glass for 5 min, transfer it to room temperature for cooling.

[0037] (3) Surface polishing: The surface of the strengthened glass is treated with optical polishing to repair micro cracks, thereby obtaining high-crystallinity microcrystalline glass with excellent resistance to falling ball impact.

[0038] A high-crystallinity glass-ceramic with excellent falling ball impact resistance, wherein the high-crystallinity glass-ceramic is produced according to the above-mentioned production process.

[0039] Comparative Example 1

[0040] The difference between this comparative example and Example 2 is that the preheating temperature of the primary strengthening and the secondary strengthening is 350°C and the time is 15 min; the primary strengthening adopts a mixed molten salt of sodium nitrate and potassium nitrate, and the mass ratio of sodium nitrate to potassium nitrate is 70%:30%, and the secondary strengthening adopts a mixed molten salt of sodium nitrate and potassium nitrate, and the mass ratio of sodium nitrate to potassium nitrate is 10%:90%; no surface polishing treatment is performed.

[0041] Comparative Example 2

[0042] The difference between this comparative example and Example 2 is that: the first strengthening adopts a mixed molten salt of sodium nitrate and potassium nitrate, and the mass ratio of sodium nitrate to potassium nitrate is 70%:30%, and the second strengthening adopts a mixed molten salt of sodium nitrate and potassium nitrate, and the mass ratio of sodium nitrate to potassium nitrate is 10%:90%; no surface polishing treatment is performed.

[0043] Comparative Example 3

[0044] The difference between this comparative example and Example 2 is that the preheating temperature of the primary strengthening and the secondary strengthening is 350° C. and the time is 15 min; and no surface polishing treatment is performed.

[0045] Comparative Example 4

[0046] The difference between this comparative example and Example 2 is that the preheating temperature of the primary strengthening and the secondary strengthening is 350°C and the time is 15 minutes; the primary strengthening adopts a mixed molten salt of sodium nitrate and potassium nitrate, and the mass ratio of sodium nitrate to potassium nitrate is 70%:30%, and the secondary strengthening adopts a mixed molten salt of sodium nitrate and potassium nitrate, and the mass ratio of sodium nitrate to potassium nitrate is 10%:90%.

[0047] Comparative Example 5

[0048] The difference between this comparative example and Example 2 is that the preheating temperature of the primary strengthening and the secondary strengthening is 350° C. and the time is 15 minutes.

[0049] Comparative Example 6

[0050] The difference between this comparative example and Example 2 is that the primary strengthening adopts a mixed molten salt of sodium nitrate and potassium nitrate, and the mass ratio of sodium nitrate to potassium nitrate is 70%:30%, and the secondary strengthening adopts a mixed molten salt of sodium nitrate and potassium nitrate, and the mass ratio of sodium nitrate to potassium nitrate is 10%:90%.

[0051] Comparative Example 7

[0052] The difference between this comparative example and Example 2 is that no surface polishing treatment is performed.

[0053] The high-crystallinity glass-ceramics obtained by the production process of Examples 1-3 of the present invention and Comparative Examples 1-7 were tested for their anti-falling ball impact performance. The test conditions are as follows: a 64g steel ball is dropped from 30cm to the strengthened 0.55mm thick 2D high-crystallinity glass-ceramics (the raw material is a white sheet of Chiyan C1 glass-ceramics), and then dropped once at 9 points, with the height raised every 5cm. Ten pieces are tested at each height, and the lowest crack height is recorded. The test results are shown in the following table.

[0054]

[0055]

[0056] As can be seen from the above table, the production process of the present invention uses high-temperature and long-term preheating, pure sodium molten salt for primary strengthening, pure potassium molten salt for secondary strengthening, and optical polishing to treat the surface after strengthening. The resulting high-crystallinity microcrystalline glass has a drop-ball impact resistance that can be improved by more than 75%.

[0057] The above embodiments are preferred implementation schemes of the present invention. In addition, the present invention may 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 production process for improving the ball drop impact resistance of high-crystallinity glass-ceramics, characterized by: The steps include: (1) Primary strengthening: preheat the high crystallinity glass-ceramics at 380-450°C for 20-30 min, then place it in a molten salt of sodium nitrate and strengthen it at 450-490°C for 6-7 h. After dripping salt on the strengthened glass for 4-6 min, transfer it to room temperature for cooling. (2) Secondary strengthening: preheat the high crystallinity glass-ceramics at 380-450°C for 20-30 min, then place it in molten potassium nitrate at 370-410°C for 15-25 min, drip salt on the strengthened glass for 4-6 min, and then transfer it to room temperature for cooling; (3) Surface polishing: The surface of the strengthened glass is treated with optical polishing to repair micro cracks, thereby obtaining high-crystallinity microcrystalline glass with excellent resistance to falling ball impact.

2. The production process for improving the falling ball impact resistance of high-crystallinity glass-ceramics according to claim 1, characterized in that: In the step (1), the preheating temperature is 420-450° C. and the preheating time is 20-30 min.

3. The production process for improving the falling ball impact resistance of high-crystallinity glass-ceramics according to claim 1, characterized in that: In the step (1), the strengthening temperature is 460° C. and the time is 6.5 h.

4. The production process for improving the falling ball impact resistance of high-crystallinity glass-ceramics according to claim 1, characterized in that: In the step (2), the preheating temperature is 420-450° C. and the preheating time is 20-30 minutes.

5. The production process for improving the falling ball impact resistance of high-crystallinity glass-ceramics according to claim 1, characterized in that: In the step (2), the strengthening temperature is 390° C. and the time is 20 minutes.

6. A high-crystallinity glass-ceramic with excellent falling ball impact resistance, characterized in that: The high-crystallinity glass-ceramics is produced according to the production process described in any one of claims 1-5.

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