Transparent microcrystalline glass as well as preparation method and application thereof

Abstract

The invention provides transparent microcrystalline glass as well as a preparation method and application thereof. The microcrystalline glass contains an Al < 4 > B < 2 > O < 9 > nanorod, or simultaneously contains the Al < 4 > B < 2 > O < 9 > nanorod and Li < x > Al < x > Si < 1-x > O < 2 > nanocrystals. The transparent microcrystalline glass is prepared by adopting a melting-forming-heat treatment method. The transparent microcrystalline glass is applied to the fields of information terminal protection cover plates, transparent protection windows and daily utensils. The controllable preparation of the rod-like structure nanorod in the transparent glass ceramic is realized, and the mechanical property of the glass ceramic is obviously improved. Moreover, the transparent glass ceramic has good ion exchange capacity, sodium-lithium ion exchange and potassium-sodium ion exchange can be realized, and the mechanical property of the glass ceramic is further improved.

Description

Technical Field

[0001] The present invention relates to a glass-ceramic, and in particular to a transparent glass-ceramic and a preparation method and application thereof. Background Art

[0002] Compared to glass, transparent microcrystalline glass contains dispersed nanocrystals, which usually have better mechanical properties such as impact resistance, hardness, and fracture toughness than its corresponding glass body. It has important application value in the fields of information display devices, transparent protective windows, and daily utensils. The composition, structure, and morphology of nanocrystals in microcrystalline glass have a great influence on the overall performance of microcrystalline glass. In existing transparent microcrystalline glass, nanocrystals usually have a spherical structure, and nanocrystals with morphologies such as dendritic and rod-like structures are rarely seen. The controllable preparation of nanorod crystals in transparent microcrystalline glass has positive significance for inhibiting the expansion of microcracks and improving the fracture toughness and impact resistance of microcrystalline glass.

[0003] Aluminum borate (Al4B2O9) has a high elastic modulus and good chemical stability, and its whiskers (typically larger than 1 micron) have a wide range of applications in material reinforcement. Transparent glass-ceramics containing Al4B2O9 nanocrystals have been reported, but these nanocrystals are typically nearly spherical, resulting in limited improvements in the mechanical properties of the transparent glass-ceramics, making it difficult to further enhance the fracture toughness and impact resistance of the glass-ceramics. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a transparent microcrystalline glass with good fracture toughness and impact resistance, as well as a preparation method and application thereof.

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

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

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

[0008] Preferably, based on 1 mm thick microcrystalline glass, the microcrystalline glass is transparent in the visible light band, and the transmittance at 550 nm is higher than 50%.

[0009] Preferably, in terms of molar percentage, the transparent microcrystalline glass comprises the following composition: the transparent microcrystalline glass comprises the following composition: 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 a combination of more than two of Li, Na, 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 also 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.

[0013] The transparent microcrystalline glass is prepared by a melting-forming-heat treatment method. The microcrystalline glass is melted in the range of 1550-1650°C, and after melting and clarification, it is formed. The glass has good viscosity-temperature characteristics, and the forming methods include casting forming, float forming, etc. The heat treatment uses thermal analysis to determine the transition temperature and crystallization peak temperature of the glass, and determines the heat treatment process system of the glass. The relevant heat treatment process system can include one-step heat treatment or two-step heat treatment. By adjusting the heat treatment process parameters, the size of the Al4B2O9 nanorods in the microcrystalline glass, the crystallization content, and the transmittance of the microcrystalline glass can be adjusted; at the same time, increasing the crystallization content of the Al4B2O9 nanorods in the microcrystalline glass can further improve the mechanical properties of the microcrystalline glass, such as hardness, elastic modulus, fracture toughness and impact resistance.

[0014] Preferably, the transparent microcrystalline glass can undergo sodium-lithium and potassium-sodium ion exchange, or potassium-sodium ion exchange. The alkali metal ions in the microcrystalline glass are not components of the Al4B2O9 nanorods, and the alkali metal ions in the microcrystalline glass are mainly distributed in the glass phase, so that the microcrystalline glass has good ion exchange performance. In order to further improve the mechanical properties of the microcrystalline glass described in the present invention, the microcrystalline glass can be further subjected to sodium-lithium and potassium-sodium ion exchange. The ion exchange can realize sodium-lithium and potassium-sodium ion exchange through a mixed molten salt of NaNO3 and KNO3; it can also be realized by respectively realizing sodium-lithium and potassium-sodium ion exchange in NaNO3 molten salt and KNO3 molten salt. Parameters such as molten salt composition, ion exchange temperature and time can be adjusted according to parameters such as the surface compressive stress and stress layer depth of the actual microcrystalline glass after ion exchange. The microcrystalline glass after ion exchange has good fracture toughness, and is 10kgf / mm 2 Under pressure, there are no visible microcracks at the indentation.

[0015] The transparent microcrystalline glass is used in the fields of information terminal protection cover plates, transparent protective windows, and daily utensils.

[0016] The present invention achieves controllable preparation of Al4B2O9 nanorods in borosilicate glass by optimizing the glass composition, wherein the nanorods are randomly distributed in the glass, and their arrangement directions are staggered, thereby making the microcrystalline glass have good resistance to crack propagation and good impact resistance. At the same time, in the microcrystalline glass, alkali metal ions do not participate in the crystallization of the glass, so that the transparent microcrystalline glass containing Al4B2O9 nanorods has good ion exchange performance, and the mechanical properties of the transparent microcrystalline glass can be further improved 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 described in the present invention has good ion exchange capacity and can realize sodium-lithium ion exchange and potassium-sodium ion exchange, further improving the mechanical properties of the microcrystalline glass. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In the following figures, the five-digit AAABB number represents a one-step heat treatment, where AAA represents the heat treatment temperature (unit: degrees Celsius) and BB represents the heat treatment time (unit: hours). AAABB+CCCDD represents a two-step heat treatment, where AAA and CCC represent the temperatures (unit: degrees Celsius) of the first and second steps, respectively, and BB and DD represent the heat treatment time (unit: hours). For example, when BB=05, the heat treatment time is 5 hours, and when BB=10, the heat treatment time is 10 hours. AP represents unheated glass.

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

[0022] Figure 1 This is the XRD pattern of the glass-ceramics described in Example 2. As the heat treatment temperature increases, the crystallization peak of the nanocrystals in the glass gradually becomes stronger.

[0023] Figure 2 This is the transmission spectrum of the glass-ceramics described in Example 2. As the heat treatment temperature increases, the transmittance of the glass-ceramics in the short-wavelength band decreases due to the precipitation and growth of nanocrystals in the glass.

[0024] Figure 3 This is the XRD pattern of the glass-ceramics obtained in Example 2 (two-step heat treatment). Compared to the one-step heat treatment, the two-step heat treatment produces weaker diffraction peaks and a larger full width at half maximum (FWHM). Using the Scherrer formula, the length of the nanocrystals in the (120) direction is 5.14 nm, the length of the nanocrystals in the (110) direction is 6.5 nm, and the aspect ratio is 1.27.

[0025] Figure 4 This is the transmittance spectrum of the glass-ceramics (two-step heat treatment) described in Example 2. Compared with the one-step heat treatment, the transmittance of the glass-ceramics obtained by the two-step heat treatment is higher overall.

[0026] Figure 5 Transmission electron micrographs of the glass-ceramics described in Example 2 (treated at 850°C for 10 hours). The nanocrystals in the images all exhibit rod-like structures. (a) shows the distribution of nanocrystals in the glass-ceramics sample, (b) is a high-resolution image of a single nanocrystal, and (c) is an FFT (fast Fourier transformation) plot of the single nanocrystal in (b). The results in (b) and (c) indicate that the nanocrystals are Al₄B₂O₄ nanocrystals.

[0027] Figure 6 This is the XRD pattern of the glass-ceramics described in Example 4 (two-step heat treatment).

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

[0029] Figure 8 This is the XRD pattern of the microcrystalline glass described in Example 15.

[0030] Figure 9 This is the XRD pattern of the microcrystalline glass described in Example 16.

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

[0032] Figure 11 This is the XRD pattern of the microcrystalline glass described in Example 17.

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

[0034] Figure 13 This is the XRD pattern of the microcrystalline glass described in Example 18.

[0035] Figure 14 This is the XRD pattern of the microcrystalline glass described in Example 21.

[0036] Figure 15 This is the XRD pattern of the microcrystalline glass described in Example 26.

[0037] Figure 16 This is the XRD pattern of the glass-ceramics described in Example 29. The two-step heat treatment method is adopted, and the glass-ceramics contains Al4B2O9 nanorods and LiAlSi3O8 crystals.

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

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

[0040] Figure 19 This is the transmittance spectrum of the glass-ceramics described in Example 37. A two-step heat treatment was used. When the second heat treatment temperature was low, the glass-ceramics contained only Al₄B₂O₄ nanorods, resulting in a high transmittance. When the second heat treatment temperature was high, the glass-ceramics contained both Al₄B₂O₄ nanorods and LiAlSi₃O₄ crystals, resulting in a low transmittance.

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

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

[0043] Figure 22 Transmission electron microscope photos of the glass-ceramics described in Comparative Example 2. (a) The overall distribution of nanocrystals in the glass-ceramics. (b) The small-sized nanocrystals, whose interplanar spacing corresponds to that of Al4B2O9 crystals. (c) The large-sized nanocrystals, whose interplanar spacing corresponds to that of Li x Al x Si 1-x O2 crystal corresponds to. (a) The results show that due to Li x Al x Si 1-x The O2 crystal phase is large in size, and its refractive index is somewhat different from that of the glass matrix, which causes the crystal phase to have a significant scattering effect on visible light, reducing the transmittance of the microcrystalline glass.

[0044] Figure 23 This is the Na ion distribution in the surface layer of the glass and glass-ceramics obtained after Na-Li ion exchange in Example 2. The ion exchange was conducted using molten NaNO3 at 460°C for 4 hours. The Na ion distribution depth in the unheated sample (AP) after ion exchange was approximately 150 μm. The ion exchange depth in the glass-ceramics obtained after heat treatment at 750°C for 10 hours or 800°C for 10 hours was approximately 300 μm. These results demonstrate the excellent ion exchange capacity of this type of glass-ceramics.

[0045] Figure 24 This is the stress stripe distribution tested after the two-step ion exchange of the microcrystalline glass described in Example 2 (heat treatment conditions: 800℃ / 10h). The ion exchange used is specifically as follows: the first step of ion exchange: the molten salt is NaNO3 molten salt, and the ion exchange temperature / time is 460℃ / 4 hours; the second step of ion exchange: the molten salt is KNO3, and the ion exchange temperature / time is 460℃ / 4 hours. The stress distribution of the microcrystalline glass after ion exchange was tested using FSM-6000LE. The results showed that the surface compressive stress of the glass after the two-step ion exchange was 672MPa, and the stress layer depth was 12.3 microns. This shows that this type of microcrystalline glass also has good K-Na ion exchange capabilities.

[0046] Figure 25The Vickers hardness of the unheat-treated glass and the glass-ceramic before and after the ion exchange of the glass-ceramic described in Example 2. In the figure, AP represents the unheat-treated glass sample, and 75010 and 80010 represent the glass-ceramic obtained by heat treatment at 750°C and 800°C for 10 hours, respectively. Non-ion exchange represents the Vickers hardness of the unheat-treated glass sample and the glass-ceramic before ion exchange (square symbols in the figure). In NaNO3 molten salt, after exchange at 460°C for 10 hours, the Vickers hardness values ​​of all samples increased (circular symbols in the figure); on the basis of the first step of ion exchange, the Vickers hardness values ​​of all samples were further increased after further exchange at 460°C for 10 hours in KNO3 molten salt (triangle symbols in the figure).

[0047] Figure 26 These are the Vickers hardness tester indentation diagrams of the unheat-treated glass, microcrystalline glass, and microcrystalline glass after ion exchange described in Example 3. In the figure, AP represents the unheat-treated sample, which did not produce visible microcracks under a pressure of 19.6N. The microcrystalline glass obtained by treating the composition sample at 800℃ / 10h did not produce visible microcracks under a pressure of 24.5N. After ion exchange (exchange in a molten salt of 20% by weight NaNO3+80% by weight KNO3 at a temperature of 480℃ for 4h), the microcrystalline glass did not produce visible microcracks under a pressure of 98.0N. The above results show that microcrystallization and ion exchange significantly enhance the ability of microcrystalline glass to resist the generation and expansion of cracks. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0049] The following is an explanation of the specific examples. The glass compositions in the following examples (Tables 1 to 10) and comparative examples (Tables 11 to 14) are expressed in mole percentages.

[0050] It should be noted that in the accompanying drawings, for some embodiments, such as embodiment 2, Figures 1 to 4 In this study, we also investigated the XRD and transmittance patterns of samples obtained using different heat treatment regimes. The following table only provides the crystal phase type, transmittance, and Vickers hardness data for Example 2 under a specific heat treatment regime. For data under other heat treatment regimes, please refer to the accompanying figures.

[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] The raw materials listed in the present invention, as well as the upper and lower limits of the raw materials, the upper and lower limits of the process parameters, and the interval values ​​can all realize the present invention. The embodiments are not listed one by one here; any simple modifications, equivalent changes or modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A transparent glass-ceramic, characterized in that: The transparent microcrystalline glass contains Al4B2O9 nanorods, or contains Al4B2O9 nanorods and Li x Al x Si 1-x O2 nanocrystals.

2. The transparent glass-ceramics according to claim 1, wherein: The transparent microcrystalline glass can undergo sodium-lithium and potassium-sodium ion exchange, or potassium-sodium ion exchange.

3. The transparent glass-ceramics according to claim 1, wherein: The Al4B2O9 nanorods have an axial length less than 200 nm, a radial width less than 50 nm, and an aspect ratio greater than 1.

2.

4. The transparent glass-ceramics according to claim 1, wherein: The microcrystalline glass is based on 1 mm thick, and the microcrystalline glass is transparent in the visible light band, and the transmittance at 550 nm is higher than 50%.

5. The transparent glass-ceramics according to claim 1, wherein: In terms of molar percentage, the transparent microcrystalline glass includes the following composition: 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 a combination of two or more of Li, Na, and K, and K2O<2.

6. The transparent glass-ceramics according to claim 5, wherein: SiO2+Al2O3≤82.

56.

7. The transparent glass-ceramics according to claim 5, wherein: 1.75≤(SiO2-Al2O3) / B2O3≤4.

4.

8. The transparent glass-ceramics according to claim 5, wherein: The transparent microcrystalline glass also 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.

9. The method for preparing the transparent glass-ceramics according to claim 1, wherein: The transparent microcrystalline glass is prepared by a melting-forming-heat treatment method.

10. Application of the transparent micro-ceramic glass as claimed in claim 1 in the fields of information terminal protective cover plates, transparent protective windows, and daily utensils.

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