Transparent microcrystalline glass, and preparation method and application thereof

Abstract

The application provides transparent microcrystalline glass and a preparation method and application thereof. The microcrystalline glass contains Al4B2O9 nanorods, or contains Al4B2O9 nanorods and Li x Al x Si 1‑x O2 nanocrystals. The transparent microcrystalline glass is prepared by a melting-shaping-heat treatment method. The transparent microcrystalline glass is applied to the fields of information terminal protective cover plates, transparent protective windows and daily utensils. The application realizes controllable preparation of rod-shaped structure nanorods in the transparent microcrystalline glass, and significantly improves the mechanical properties of the microcrystalline glass. Moreover, the transparent microcrystalline glass has good ion exchange capacity, can realize sodium-lithium ion exchange and potassium-sodium ion exchange, and further improves the mechanical properties of the microcrystalline glass.

Description

Technical Field

[0001] This invention relates to a microcrystalline glass, and more particularly to a transparent microcrystalline glass, its preparation method, and its application. Background Technology

[0002] Compared to glass, transparent glass-ceramics possess dispersed nanocrystals, typically exhibiting superior mechanical properties such as impact resistance, hardness, and fracture toughness. This makes them valuable for applications in information display devices, transparent protective windows, and everyday tableware. The composition, structure, and morphology of nanocrystals in glass-ceramics significantly influence their overall performance. Currently, nanocrystals in transparent glass-ceramics typically exhibit spherical structures, with dendritic or rod-like structures being rare. Achieving controllable fabrication of nanorod-like crystals in transparent glass-ceramics is crucial for suppressing microcrack propagation and improving the fracture toughness and impact resistance of glass-ceramics.

[0003] Aluminum borate (Al4B2O9) possesses a high elastic modulus and good chemical stability, and its whiskers (typically larger than 1 micrometer) have wide applications in material reinforcement. Transparent glass-ceramics containing Al4B2O9 nanocrystals have been reported; however, these Al4B2O9 nanocrystals are usually nearly spherical, limiting their improvement on the mechanical properties of transparent glass-ceramics and making it difficult to further enhance their fracture toughness and impact resistance. Summary of the Invention

[0004] This invention provides a transparent microcrystalline glass with good fracture toughness and impact resistance, as well as its preparation method and application, to solve the above-mentioned technical problems.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A transparent microcrystalline glass, characterized in that the microcrystalline glass contains Al4B2O9 nanorods, or simultaneously contains Al4B2O9 nanorods and Li. x Al x Si 1-x O2 nanocrystals.

[0007] Preferably, the Al4B2O9 nanorod has an axial length of less than 200 nm, a radial width of less than 50 nm, and an aspect ratio of greater than 1.2.

[0008] Preferably, the microcrystalline glass is based on a thickness of 1 mm, which is transparent in the visible light band and has a transmittance of more than 50% at 550 nm.

[0009] Preferably, the transparent microcrystalline glass comprises the following components by mole percentage: 49.0≤SiO2≤66.03; 15.6≤Al2O3≤26.53; 8.5≤B2O3≤15.84; 7.3≤M2O≤14.5; Al2O3>B2O3, wherein M is one or more of Li, Na, and K, and K2O<2.

[0010] Preferably, SiO2+Al2O3≤82.56.

[0011] Preferably, 1.75≤(SiO2-Al2O3) / B2O3≤4.4.

[0012] Preferably, the transparent microcrystalline glass further comprises: 0≤ZnO≤7.5; 0≤MgO+CaO≤10; 0≤SrO+BaO≤7.5; 0≤Y2O3≤1; 0≤TiO2≤5.7; 0≤ZrO2≤3.9; 0≤P2O5≤2; 0≤Ga2O3≤2.

[0013] The transparent glass-ceramic is prepared using a melt-forming-heat treatment method. The glass-ceramic is melted within the range of 1550-1650℃, and after melting and clarification, it is formed. The glass exhibits good viscosity-temperature characteristics. The forming methods include casting and float glass forming. The heat treatment utilizes thermal analysis to determine the glass's transition temperature and crystallization peak temperature, thus determining the heat treatment process. This process can include one-step or two-step heat treatment. Adjusting the heat treatment process parameters can regulate the size of the Al4B2O9 nanorods, the crystallization content, and the transmittance of the glass-ceramic. Furthermore, increasing the crystallization content of the Al4B2O9 nanorods can further improve the glass-ceramic's hardness, elastic modulus, fracture toughness, and impact resistance.

[0014] Preferably, the transparent glass-ceramic can undergo sodium-lithium and potassium-sodium ion exchange, or potassium-sodium ion exchange. In this glass-ceramic, alkali metal ions are not part of the Al4B2O9 nanorods; they are mainly distributed in the glass phase, giving the glass-ceramic good ion exchange performance. To further improve the mechanical properties of the glass-ceramic of this invention, sodium-lithium and potassium-sodium ion exchange can be further performed. This ion exchange can be achieved using a mixed molten salt of NaNO3 and KNO3; alternatively, it can be achieved separately in NaNO3 and KNO3 molten salts. Parameters such as molten salt composition, ion exchange temperature, and time can be adjusted based on the actual surface compressive stress and stress layer depth of the glass-ceramic after ion exchange. The ion-exchanged glass-ceramic exhibits good fracture toughness at 10 kgf / mm². 2 Under pressure, no visible microcracks were found at the indentation.

[0015] The aforementioned transparent microcrystalline glass is used in information terminal protective covers, transparent protective windows, and daily utensils.

[0016] This invention achieves the controllable preparation of Al4B2O9 nanorods in borosilicate glass by optimizing the glass composition. The nanorods are randomly distributed in the glass with interlaced orientations, thereby giving the glass-ceramic good resistance to crack propagation and good impact resistance. At the same time, in this glass-ceramic, alkali metal ions do not participate in glass crystallization, thus giving the transparent glass-ceramic containing Al4B2O9 nanorods good ion exchange performance, which can further improve the mechanical properties of the transparent glass-ceramic through ion exchange.

[0017] Compared with the prior art, the present invention has the following advantages and technical effects:

[0018] (1) The present invention realizes the controllable preparation of rod-shaped nanorods in transparent microcrystalline glass, which significantly improves the mechanical properties of microcrystalline glass.

[0019] (2) The transparent microcrystalline glass of the present invention has good ion exchange capacity and can realize sodium-lithium ion exchange and potassium-sodium ion exchange, thereby further improving the mechanical properties of the microcrystalline glass. Attached Figure Description

[0020] In the attached diagrams, AAABB (five digits) represents a one-step heat treatment, where AAA represents the heat treatment temperature (in degrees Celsius) and BB represents the heat treatment time (in hours); AAABB+CCCDD represents a two-step heat treatment, where AAA and CCC represent the temperatures (in degrees Celsius) of the first and second heat treatment steps, respectively, and BB and DD represent the heat treatment times (in hours). For example, when BB = 0.5, it indicates a heat treatment time of 5 hours; when BB = 10, it indicates a heat treatment time of 10 hours. AP represents untreated glass.

[0021] In the following figures, the thickness of all the untreated and heat-treated glass-ceramic samples used for transmittance testing is 1 ± 0.05 mm.

[0022] Figure 1 The image shows the XRD pattern of the microcrystalline glass described in Example 2. As the heat treatment temperature increases, the crystallization peaks of the nanocrystals in the glass gradually become stronger.

[0023] Figure 2 The transmission spectrum of the microcrystalline glass described in Example 2 is shown. Increasing the heat treatment temperature causes a decrease in the transmittance of the microcrystalline glass in the short wavelength range due to the precipitation and growth of nanocrystals within the glass.

[0024] Figure 3 The image shows the XRD pattern of the glass-ceramic obtained in Example 2 (two-step heat treatment). Compared with the one-step heat treatment, the diffraction peaks of the glass-ceramic obtained by the two-step heat treatment are weaker, and the full width at half maximum (FWHM) of the diffraction peaks is larger. Calculated using the Scherrer formula, the nanocrystal length in the (120) direction is 5.14 nm, the nanocrystal length in the (110) direction is 6.5 nm, and the aspect ratio is 1.27.

[0025] Figure 4 The image shows the transmission spectrum of the glass-ceramic (two-step heat treatment) described in Example 2. Compared to the one-step heat treatment, the glass-ceramic obtained by the two-step heat treatment has a higher overall transmittance.

[0026] Figure 5 The images show transmission electron microscopy (TEM) images of the glass-ceramic sample described in Example 2 (treated at 850°C for 10 hours). The nanocrystals in the images all exhibit a rod-like structure. Image (a) shows the distribution of nanocrystals in the glass-ceramic sample, image (b) is a high-resolution image of a single nanocrystal, and image (c) is the FFT (fast Fourier transformation) image of a single nanocrystal in image (b). Images (b) and (c) indicate that the nanocrystals are Al4B2O9 nanocrystals.

[0027] Figure 6 The image shows the XRD pattern of the glass-ceramic described in Example 4 (two-step heat treatment).

[0028] Figure 7 The XRD pattern of the microcrystalline glass described in Example 13 (two-step heat treatment).

[0029] Figure 8 The image shows the XRD pattern of the microcrystalline glass described in Example 15.

[0030] Figure 9 The image shows the XRD pattern of the microcrystalline glass described in Example 16.

[0031] Figure 10 The transmission spectrum is that of the microcrystalline glass described in Example 16.

[0032] Figure 11 The image shows the XRD pattern of the microcrystalline glass described in Example 17.

[0033] Figure 12 The transmission spectrum is that of the microcrystalline glass described in Example 17.

[0034] Figure 13 The image shows the XRD pattern of the microcrystalline glass described in Example 18.

[0035] Figure 14 The image shows the XRD pattern of the microcrystalline glass described in Example 21.

[0036] Figure 15 The image shows the XRD pattern of the microcrystalline glass described in Example 26.

[0037] Figure 16 The image shows the XRD pattern of the glass-ceramic described in Example 29. A two-step heat treatment method was used, and the glass-ceramic simultaneously contains Al4B2O9 nanorods and LiAlSi3O8 crystals.

[0038] Figure 17 The transmission spectrum is that of the microcrystalline glass described in Example 29.

[0039] Figure 18 The image shows the XRD pattern of the glass-ceramic described in Example 37. A two-step heat treatment method was used; when the second heat treatment temperature was low, the glass-ceramic contained only Al4B2O9 nanorods; when the second heat treatment temperature was high, the glass-ceramic contained both Al4B2O9 nanorods and LiAlSi3O8 crystals.

[0040] Figure 19 The transmission spectrum of the glass-ceramic described in Example 37 is shown. A two-step heat treatment method was used. When the second heat treatment temperature was low, the glass-ceramic contained only Al4B2O9 nanorods, resulting in high transmittance. When the second heat treatment temperature was high, the glass-ceramic contained both Al4B2O9 nanorods and LiAlSi3O8 crystals, resulting in low transmittance.

[0041] Figure 20 The XRD pattern of the microcrystalline glass described in Example 36 (two-step heat treatment).

[0042] Figure 21 The transmission spectrum of the microcrystalline glass described in Example 36 (two-step heat treatment).

[0043] Figure 22 The images show transmission electron microscopy (TEM) images of the microcrystalline glass described in Comparative Example 2. (a) The overall distribution of nanocrystals in the microcrystalline glass. (b) Small-sized nanocrystals, whose interplanar spacing corresponds to that of Al4B2O9 crystals. (c) Large-sized nanocrystals, whose interplanar spacing corresponds to that of Li… x Al x Si 1-x The O2 crystal corresponds to (a) the results shown in Figure 1. x Al x Si 1-x The O2 crystal phase is relatively large, and its refractive index differs from that of the glass matrix. This results in the crystal phase having a significant scattering effect on visible light, reducing the transmittance of the glass-ceramic.

[0044] Figure 23 This is a Na ion distribution map on the surface of the sample after Na-Li ion exchange between the glass and the microcrystalline glass described in Example 2. The ion exchange was performed using NaNO3 molten salt at a temperature of 460°C for 4 hours. After ion exchange, the Na ion distribution depth of the untreated sample (AP) was approximately 150 micrometers; the ion exchange depth of the microcrystalline glass obtained after heat treatment at 750°C / 10h or 800°C / 10h was approximately 300 micrometers. These results demonstrate that this type of microcrystalline glass possesses excellent ion exchange capacity.

[0045] Figure 24 This image shows the stress stripe distribution of the microcrystalline glass described in Example 2 (heat treatment conditions: 800℃ / 10h) after a two-step ion exchange. The specific ion exchange process was as follows: First step: NaNO3 molten salt, ion exchange temperature / time 460℃ / 4h; Second step: KNO3 molten salt, ion exchange temperature / time 460℃ / 4h. The stress distribution of the microcrystalline glass after ion exchange was tested using an FSM-6000LE. The results show that the surface compressive stress of the glass after the two-step ion exchange was 672 MPa, and the stress layer depth was 12.3 micrometers. This indicates that this type of microcrystalline glass also possesses good K-Na ion exchange capabilities.

[0046] Figure 25The figures show the Vickers hardness of the untreated glass and the microcrystalline glass before and after ion exchange as described in Example 2. In the figure, AP represents the untreated glass sample, and 75010 and 80010 represent the microcrystalline glass obtained after heat treatment at 750℃ and 800℃ for 10 hours, respectively. "Untreated" represents the Vickers hardness of the untreated glass sample and the microcrystalline glass before ion exchange (square symbol in the figure). In NaNO3 molten salt, after ion exchange at 460℃ for 10 hours, the Vickers hardness values ​​of all samples increased (circle symbol in the figure); based on the first step of ion exchange, further ion exchange in KNO3 molten salt at 460℃ for 10 hours further increased the Vickers hardness values ​​of all samples (triangle symbol in the figure).

[0047] Figure 26 The figures show Vickers hardness indentation images of the untreated glass, glass-ceramic, and ion-exchanged glass-ceramic described in Example 3. In the figures, AP represents the untreated sample, which showed no visible microcracks under 19.6 N pressure. The glass-ceramic obtained by treating this sample at 800°C for 10 h showed no visible microcracks under 24.5 N pressure. After ion exchange (in a molten salt solution of 20% NaNO3 + 80% KNO3 by weight at 480°C for 4 h), the glass-ceramic showed no visible microcracks under 98.0 N pressure. These results demonstrate that microcrystallization and ion exchange significantly improve the glass-ceramic's resistance to crack initiation and propagation. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0049] The following specific examples illustrate this. In the examples (Tables 1 to 10) and comparative examples (Tables 11 to 14) described below, the glass composition is expressed as a molar percentage.

[0050] It should be noted that, in the accompanying drawings, for some embodiments, such as embodiment 2, in... Figures 1 to 4 Furthermore, the XRD and transmittance spectra of samples obtained using different heat treatment regimes were investigated. The table below only shows the crystal phase type, transmittance, Vickers hardness, and other data for Example 2 under a specific heat treatment regime; data for other heat treatment regimes can be found in the accompanying drawings.

[0051] Table 1

[0052]

[0053] Table 2

[0054]

[0055]

[0056] Table 3

[0057]

[0058] Table 4

[0059]

[0060]

[0061] Table 5

[0062]

[0063] Table 6

[0064]

[0065] Table 7

[0066]

[0067]

[0068] Table 8

[0069]

[0070] Table 9

[0071]

[0072]

[0073] Table 10

[0074]

[0075]

[0076] Table 11

[0077]

[0078] Table 12

[0079]

[0080]

[0081] Table 13

[0082]

[0083] Table 14

[0084]

[0085]

[0086] All the raw materials listed in this invention, as well as the upper and lower limits of the raw materials, the upper and lower limits of the process parameters, and the range of values, can realize this invention. Examples are not listed one by one here. Any simple modifications, equivalent changes, or alterations made to the above embodiments based on the technical essence of this invention shall still fall within the scope of the technical solution of this invention.

Claims

1. A transparent microcrystalline glass, characterized in that, The transparent microcrystalline glass contains Al4B2O9 nanorods, or simultaneously contains Al4B2O9 nanorods and Li. x Al x Si 1-x O2 nanocrystals, the transparent microcrystalline glass comprising the following components by molar percentage: 49.0≤SiO2≤66.03; 15.6≤Al2O3≤26.53; 8.5≤B2O3≤15.84; 7.3≤M2O≤14.5; Al2O3>B2O3, wherein M is one or more of Li, Na, and K, K2O<2, and 1.75≤(SiO2-Al2O3) / B2O3≤4.

4.

2. The transparent microcrystalline glass as described in claim 1, characterized in that, The transparent microcrystalline glass can perform sodium-lithium and potassium-sodium ion exchange, or potassium-sodium ion exchange.

3. The transparent microcrystalline glass as described in claim 1, characterized in that, The Al4B2O9 nanorods have an axial length of less than 200 nm, a radial width of less than 50 nm, and an aspect ratio greater than 1.

2.

4. The transparent microcrystalline glass as described in claim 1, characterized in that, Based on 1 mm thick microcrystalline glass, the microcrystalline glass is transparent in the visible light band and has a transmittance of more than 50% at 550 nm.

5. The transparent microcrystalline glass as described in claim 1, characterized in that, SiO2+Al2O3≤82.

56.

6. The transparent microcrystalline glass as described in claim 1, characterized in that, The transparent microcrystalline glass further includes: 0≤ZnO≤7.5; 0≤MgO+CaO≤10; 0≤SrO+BaO≤7.5; 0≤Y2O3≤1; 0≤TiO2≤5.7; 0≤ZrO2≤3.9; 0≤P2O5≤2; 0≤Ga2O3≤2.

7. The method for preparing transparent microcrystalline glass as described in claim 1, characterized in that, The transparent microcrystalline glass is prepared by a melt-forming-heat treatment method.

8. The application of the transparent microcrystalline glass as described in claim 1 in the fields of information terminal protective covers, transparent protective windows, and daily utensils.

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