Alumina-borosilicate glass-ceramics with high hardness and high crack resistance and a preparation method thereof

Abstract

The application relates to the field of special glass materials, in particular to high-hardness and high-anti-crack alumina-borosilicate glass ceramic and a preparation method thereof. The high-hardness and high-anti-crack alumina-borosilicate glass ceramic is composed of the following raw materials in terms of molar percentage: Al2O3 30-36%, B2O3 20-28%, SrO 8-12%, Li2O 1-3%, P2O5 0.5-2%, La2O3 8-10%, and the rest is SiO2. The application comprises the following steps: weighing the raw materials according to the formula, mixing and stirring, melting treatment, casting forming, annealing treatment, and obtaining base glass; performing programmed temperature crystallization treatment on the base glass, cooling, and obtaining high-hardness and high-anti-crack alumina-borosilicate glass ceramic. The application provides high-hardness and high-anti-crack alumina-borosilicate glass ceramic and a preparation method thereof, which can significantly improve the hardness and fracture toughness of the glass while still maintaining good anti-crack initiation ability.

Description

Technical Field

[0001] This application relates to the field of special glass materials, specifically to a high-hardness, high-crack-resistant aluminoborosilicate microcrystalline glass and its preparation method. Background Technology

[0002] The brittleness and low damage tolerance of glass materials are major obstacles to their widespread application. Academia and industry have been working to develop glasses that combine high hardness with high resistance to crack initiation. Traditional theory suggests that these two properties often conflict: high hardness requires a rigid network and high packing density, while high crack resistance requires the network to have a certain degree of compressibility or self-adaptive ability to dissipate energy.

[0003] In recent years, Al2O3-rich glass systems have been reported to simultaneously achieve high hardness and high resistance to crack initiation, the structural basis of which lies in Al. 3+ The multi-coordinate environment provides a balance between rigidity and adaptability. However, the melting temperature of this type of glass is extremely high, usually above 2000°C, and the glass-forming region is narrow, making it difficult to mass-produce.

[0004] Microcrystallization is an effective way to further improve the mechanical properties of glass. By introducing uniformly distributed nanocrystals into the glass matrix through controlled crystallization, hardness, elastic modulus, and fracture toughness can be improved simultaneously. However, for high-alumina borosilicate systems, microcrystallization often faces problems such as difficulty in controlling the crystalline phase, easy over-crystallization leading to increased brittleness, and a significant decrease in light transmittance. Therefore, developing a microcrystalline glass material that can be melted at a lower temperature and obtained through controlled microcrystallization with a specific high-hardness crystalline phase as the main component, while maintaining good crack resistance and a certain level of light transmittance, has significant technical and application value. Summary of the Invention

[0005] To address the aforementioned issues, the purpose of this application is to provide a high-hardness, high-crack-resistant aluminoborosilicate microcrystalline glass and its preparation method. Through a unique design of the glass composition, a base glass with high glass-forming ability can be obtained at ≤1625℃. By controlling the microcrystallization of this base glass, a microcrystalline glass with a specific borate crystal phase as the main component and a uniform microstructure can be further obtained. While significantly improving the glass hardness and fracture toughness, it can still maintain good resistance to crack initiation.

[0006] To achieve the above objectives, this application provides a high-hardness, high-crack-resistant aluminoborosilicate microcrystalline glass, which is composed of the following raw materials in the following molar percentages: Al2O3 30-36%, B2O3 20-28%, SrO 8-12%, Li2O 1-3%, P2O5 0.5-2%, La2O3 8-10%, with the remainder being SiO2.

[0007] Furthermore, the molar ratio of Al2O3 to the sum of the moles of SrO, Li2O, and La2O3 is ≥1.5.

[0008] A method for preparing a high-hardness, high-crack-resistant aluminoborosilicate microcrystalline glass includes the following steps: S1. Weigh the raw materials according to the formula, mix and stir, melt and treat, cast and mold, anneal and treat to obtain the base glass; S2. The base glass is subjected to programmed temperature-controlled crystallization treatment and cooled to obtain a high-hardness, high-crack-resistant aluminoborosilicate microcrystalline glass.

[0009] Furthermore, the mixing and stirring are carried out at a speed of 200-300 rpm for 3-4 hours.

[0010] Furthermore, the melting process is carried out at a melting temperature of 1600-1625℃ for 2-4 hours.

[0011] Furthermore, the annealing process is carried out at a temperature of 550-600℃ for 1-3 hours.

[0012] Furthermore, the programmed temperature control raises the temperature from room temperature to 780-840℃ at a heating rate of 1-10℃ / min, and holds the temperature at that temperature for 2-6 hours.

[0013] Furthermore, the cooling process involves cooling to room temperature at a rate of 1-2°C / min.

[0014] Furthermore, the high-hardness, high-crack-resistant aluminum borosilicate microcrystalline glass has a crystallinity of 40%-60%, and its main crystalline phases include SrB2O4 and Al5BO9.

[0015] In summary, this application has the following beneficial effects: The glass design in this application features a high-alumina region, where the molar content of Al₂O₃ exceeds the sum of alkali metal and alkaline earth metal oxides, such as Li₂O and SrO. This promotes the formation of Al₂O₃ in the network. 3+ They coexist in a multi-coordination form, with a relatively high proportion of five- and six-coordination Al. 3+ This provides network rigidity, which is beneficial for hardness, while the adaptability of the coordination number under external force provides self-adaptability, which is beneficial for crack resistance. Simultaneously, the high ionic field strength of the alkaline earth metal cation Sr is selected. 2+ and rare earth ions La 3+ These compounds not only stabilize highly coordinated aluminum, but their variable role in the structure also contributes to the network's adaptive capability. The introduction of B₂O₃ aims to lower the system's melting temperature and improve glass-forming ability. The key lies in the fact that, under the aluminous composition of this invention, B₂O₃… 3+It mainly exists in the form of triangular coordination. When subjected to indentation load, the triangularly coordinated boron units are more likely to transform into tetracoordination. This low-energy-barrier structural rearrangement process can effectively promote the local densification of glass, thereby significantly improving its resistance to crack initiation.

[0016] In this application, P2O5 and La2O3 are added. In addition to the aforementioned structural regulation effects, they can also act as effective nucleating agents or nucleation promoters. Under appropriate heat treatment, they can induce the formation of fine, uniformly distributed nanocrystalline phases, including aluminates, silicates, or lanthanum-containing phases, without triggering catastrophic large grain growth. By controlling the crystallinity, it can be ensured that a sufficient proportion of a glassy phase with high crack resistance is retained in the material, while the nanocrystals provide additional hardness and toughness enhancement.

[0017] This invention introduces multiple components, especially La2O3, and applies the principle of confusion to increase the mixing entropy of the melt, effectively suppressing the tendency of high-temperature crystallization and phase separation. This allows the high-performance composition to form a uniform, amorphous glass after melting at temperatures of 1625°C and below, providing a high-quality precursor for subsequent controllable microcrystallization.

[0018] This application achieves controlled microcrystallization of base glass, resulting in microcrystalline glass that maintains excellent resistance to crack initiation while also possessing high Vickers hardness and fracture toughness, thus achieving synergistic optimization of hardness, toughness, and crack resistance. Through composition optimization, the melting temperature of high-performance alumina-rich glass is significantly reduced from the usual >2000℃ to ≤1625℃, enabling it to be melted in conventional industrial furnaces. After microcrystallization, thanks to the nanoscale grains, the material still maintains high transparency, meeting the requirements of many applications. The microcrystalline glass prepared in this application can be directly used in applications requiring high hardness, scratch resistance, and impact resistance, such as high-end smartphones, watch covers, automotive center console screens and dashboards, precision optical component substrates, bulletproof glass, and wear-resistant windows. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 SEM image of the high-hardness, high-crack-resistant aluminoborosilicate microcrystalline glass prepared in Example 1; Figure 2 The image shows the X-ray diffraction pattern of the high-hardness, high-crack-resistant aluminoborosilicate microcrystalline glass prepared in Example 1. Detailed Implementation

[0021] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this invention.

[0022] The raw materials involved in the specific embodiments of this application are chemically pure.

[0023] Example 1 A high-hardness, high-crack-resistant aluminoborosilicate microcrystalline glass is composed of the following raw materials in the following molar percentages: SiO2: 20%, Al2O3: 32.5%, B2O3: 28%, SrO: 10%, Li2O: 1%, P2O5: 0.5%, La2O3: 8%; the calculated molar ratio of Al2O3 / (Li2O+SrO+La2O3) is 1.71.

[0024] A method for preparing a high-hardness, high-crack-resistant aluminoborosilicate microcrystalline glass includes the following steps: S1. Weigh the raw materials according to the above formula, mix and stir (250 rpm, 3 hours), melt at 1600℃ for 2 hours, cast into shape, and then anneal in a muffle furnace at 550℃ for 1 hour to obtain the base glass. S2. The base glass is heated from room temperature to 780℃ at a heating rate of 10℃ / min and held at that temperature for 2 hours. Then it is cooled to room temperature at a cooling rate of 1℃ / min to obtain a high-hardness and high-crack-resistant aluminoborosilicate microcrystalline glass.

[0025] Example 2 A high-hardness, high-crack-resistant aluminoborosilicate microcrystalline glass is composed of the following raw materials in the following molar percentages: SiO2: 30%, Al2O3: 30%, B2O3: 22%, SrO: 8%, Li2O: 1%, P2O5: 1%, La2O3: 8%; the calculated molar ratio of Al2O3 / (Li2O+SrO+La2O3) is 1.76.

[0026] A method for preparing a high-hardness, high-crack-resistant aluminoborosilicate microcrystalline glass includes the following steps: S1. Weigh the raw materials according to the above formula, mix and stir (250 rpm, 3 hours), melt at 1625℃ for 4 hours, cast into shape, and then anneal in a muffle furnace at 600℃ for 2.5 hours to obtain the base glass. S2. The base glass is heated from room temperature to 790℃ at a heating rate of 3℃ / min and held at that temperature for 3 hours. Then it is cooled to room temperature at a cooling rate of 1℃ / min to obtain a high-hardness and high-crack-resistant aluminoborosilicate microcrystalline glass.

[0027] Example 3 A high-hardness, high-crack-resistant aluminoborosilicate microcrystalline glass is composed of the following raw materials in the following molar percentages: SiO2: 27.5%, Al2O3: 31%, B2O3: 21%, SrO: 8.5%, Li2O: 1.5%, P2O5: 0.8%, La2O3: 8.5%; the calculated molar ratio of Al2O3 / (Li2O+SrO+La2O3) is 1.68.

[0028] A method for preparing a high-hardness, high-crack-resistant aluminoborosilicate microcrystalline glass includes the following steps: S1. Weigh the raw materials according to the above formula, mix and stir (250 rpm, 3 hours), melt at 1625℃ for 4 hours, cast into shape, and then anneal in a muffle furnace at 590℃ for 1.5 hours to obtain the base glass. S2. The base glass is heated from room temperature to 810℃ at a heating rate of 8℃ / min and held at that temperature for 5 hours. Then it is cooled to room temperature at a cooling rate of 1℃ / min to obtain a high-hardness, high-crack-resistant aluminoborosilicate microcrystalline glass.

[0029] Example 4 A high-hardness, high-crack-resistant aluminoborosilicate microcrystalline glass is composed of the following raw materials in the following molar percentages: SiO2: 21%, Al2O3: 35%, B2O3: 21%, SrO: 12%, Li2O: 1%, P2O5: 1%, La2O3: 9%; the calculated molar ratio of Al2O3 / (Li2O+SrO+La2O3) is 1.59.

[0030] A method for preparing a high-hardness, high-crack-resistant aluminoborosilicate microcrystalline glass includes the following steps: S1. Weigh the raw materials according to the above formula, mix and stir (250 rpm, 3 hours), melt at 1610℃ for 3 hours, cast into shape, and then anneal in a muffle furnace at 570℃ for 2 hours to obtain the base glass. S2. The base glass is heated from room temperature to 800℃ at a heating rate of 5℃ / min and held at that temperature for 4 hours. Then it is cooled to room temperature at a cooling rate of 1℃ / min to obtain a high-hardness and high-crack-resistant aluminoborosilicate microcrystalline glass.

[0031] Example 5 A high-hardness, high-crack-resistant aluminoborosilicate microcrystalline glass is composed of the following raw materials in the following molar percentages: SiO2: 21%, Al2O3: 35%, B2O3: 24.4%, SrO: 8.8%, Li2O: 1.4%, P2O5: 1.2%, La2O3: 8.2%; the calculated molar ratio of Al2O3 / (Li2O+SrO+La2O3) is 1.90.

[0032] A method for preparing a high-hardness, high-crack-resistant aluminoborosilicate microcrystalline glass includes the following steps: S1. Weigh the raw materials according to the above formula, mix and stir (250 rpm, 3 hours), melt at 1620℃ for 3.5 hours, cast into shape, and then anneal in a muffle furnace at 595℃ for 2.5 hours to obtain the base glass. S2. The base glass is heated from room temperature to 820℃ at a heating rate of 1℃ / min and held at that temperature for 6 hours. Then it is cooled to room temperature at a cooling rate of 1℃ / min to obtain a high-hardness and high-crack-resistant aluminoborosilicate microcrystalline glass.

[0033] Example 6 A high-hardness, high-crack-resistant aluminoborosilicate microcrystalline glass is composed of the following raw materials in the following molar percentages: SiO2: 23.1%, Al2O3: 34%, B2O3: 21.3%, SrO: 9.5%, Li2O: 1.2%, P2O5: 0.9%, La2O3: 10%; the calculated molar ratio of Al2O3 / (Li2O+SrO+La2O3) is 1.64.

[0034] A method for preparing a high-hardness, high-crack-resistant aluminoborosilicate microcrystalline glass includes the following steps: S1. Weigh the raw materials according to the above formula, mix and stir (250 rpm, 3 hours), melt at 1618℃ for 3 hours, cast into shape, and then anneal in a muffle furnace at 585℃ for 2 hours to obtain the base glass. S2. The base glass is heated from 25°C to 795°C at a heating rate of 6°C / min and held at that temperature for 4.5 hours. Then it is cooled to 25°C at a cooling rate of 1°C / min to obtain a high-hardness, high-crack-resistant aluminoborosilicate microcrystalline glass.

[0035] Example 7 A high-hardness, high-crack-resistant aluminoborosilicate microcrystalline glass is composed of the following raw materials in the following molar percentages: SiO2: 21.3%, Al2O3: 33.1%, B2O3: 23.5%, SrO: 10.5%, Li2O: 2.2%, P2O5: 0.6%, La2O3: 8.8%; the calculated molar ratio of Al2O3 / (Li2O+SrO+La2O3) is 1.54.

[0036] A method for preparing a high-hardness, high-crack-resistant aluminoborosilicate microcrystalline glass includes the following steps: S1. Weigh the raw materials according to the above formula, mix and stir (250 rpm, 3 hours), melt at 1608℃ for 3 hours, cast into shape, and then anneal in a muffle furnace at 575℃ for 2 hours to obtain the base glass. S2. The base glass is heated from room temperature to 830℃ at a heating rate of 4℃ / min and held at that temperature for 3.5h. Then it is cooled to room temperature at a cooling rate of 1℃ / min to obtain a high-hardness and high-crack-resistant aluminoborosilicate microcrystalline glass.

[0037] Example 8 A high-hardness, high-crack-resistant aluminoborosilicate microcrystalline glass is composed of the following raw materials in the following molar percentages: SiO2: 22%, Al2O3: 36%, B2O3: 20%, SrO: 8.2%, Li2O: 3%, P2O5: 1.8%, La2O3: 9%; the calculated molar ratio of Al2O3 / (Li2O+SrO+La2O3) is 1.78.

[0038] A method for preparing a high-hardness, high-crack-resistant aluminoborosilicate microcrystalline glass includes the following steps: S1. Weigh the raw materials according to the above formula, mix and stir (250 rpm, 3 hours), melt at 1620℃ for 2 hours, cast into shape, and then anneal in a muffle furnace at 590℃ for 3 hours to obtain the base glass. S2. The base glass is heated from room temperature to 840℃ at a heating rate of 5℃ / min and held at that temperature for 2.5h. Then it is cooled to room temperature at a cooling rate of 1℃ / min to obtain a high-hardness, high-crack-resistant aluminoborosilicate microcrystalline glass.

[0039] Compare with Example 1 The difference between this comparative example and Example 8 is that the high-hardness, high-crack-resistant aluminoborosilicate microcrystalline glass of this comparative example is composed of the following raw materials in molar percentages: SiO2: 33%, Al2O3: 25%, B2O3: 20%, SrO: 8.2%, Li2O: 3%, P2O5: 1.8%, La2O3: 9%; the calculated molar ratio of Al2O3 / (Li2O+SrO+La2O3) is 1.24.

[0040] A method for preparing a high-hardness, high-crack-resistant aluminoborosilicate microcrystalline glass includes the following steps: S1. Weigh the raw materials according to the above formula, mix and stir (250 rpm, 3 hours), melt at 1620℃ for 2 hours, cast into shape, and then anneal in a muffle furnace at 590℃ for 3 hours to obtain the base glass. S2. The base glass is heated from room temperature to 840℃ at a heating rate of 5℃ / min and held at that temperature for 2.5h. Then it is cooled to room temperature at a cooling rate of 1℃ / min to obtain a high-hardness, high-crack-resistant aluminoborosilicate microcrystalline glass.

[0041] Performance testing Functional tests were performed on the high-hardness, high-crack-resistant aluminoborosilicate microcrystalline glass prepared in Examples 1-8 compared to Comparative Example 1.

[0042] Microhardness: Tested using a Vickers hardness tester; Crack initiation resistance: The crack initiation resistance (CR) of a material is characterized by statistical analysis of the radial crack initiation probability under different loads. Indentation tests were conducted with loads of 2.94 N, 4.9 N, 9.8 N, 19.6 N, 29.4 N, and 49 N in sequence. After unloading, the number of radial cracks generated at the four corners of each indentation was observed using an optical microscope, and the crack initiation probability (i.e., the number of corners where cracks appeared / 4) was calculated. Finally, by plotting the crack initiation probability as a function of load, the critical load corresponding to a crack initiation probability of 50% was determined. This load value is defined as the crack initiation resistance value. Fracture toughness: tested using indentation fracture mechanics method; Crystallinity: analyzed using X-ray diffraction; Grain size: observed using a scanning electron microscope; Visible light transmittance: The transmittance of the sample (0.8 mm thick) in the wavelength range of 400-800 nm was measured using a UV-Vis spectrophotometer. The results are shown in Table 1. Table 1: Physical Property Test Table of Aluminoborosilicate Glass Crystal Example 1 8 21 1.2 40 50-55 92 Example 2 8.2 19 1.25 50 52-58 91 Example 3 8.5 17 1.35 55 58-63 89 Example 4 8.3 18 1.3 53 55-60 90 Example 5 8.6 15 1.4 60 53-59 90 Example 6 8.2 18 1.22 52 51-57 91 Example 7 8.3 18.5 1.28 50 56-62 89 Example 8 8.1 20 1.3 45 60-65 88 Compare with Example 1 7.4 14.3 1.1 41 58-63 83 As shown in Table 1, the microcrystalline glass prepared by this invention has excellent physical properties compared with control example 1, with a Vickers hardness of 8.0-8.6 GPa, a crack initiation resistance of 15-21 N, and a fracture toughness of 1.20-1.40 MPa·m. 0.5 The precipitated main crystalline phases are SrB₂O₄ and Al₅BO₉, with a total crystallinity of 40-60% and a grain size distribution between 50-65 nm. The transmittance of the microcrystalline glass in the 400-800 nm visible light band is 88-92% (thickness 0.8 mm). Figure 2As can be seen, the characteristic diffraction peaks of SrB2O4 and Al5BO9 are clearly visible, and the positions of the diffraction peaks are consistent with those of the standard card, verifying the accuracy of the crystal phase. There are no other significant diffraction peaks in the spectrum, indicating that the glass composition is pure and no irrelevant phases have been introduced. This conforms to the design principle of confusion, verifying the effectiveness of the composition design and preparation process of the microcrystalline glass. The microcrystalline glass prepared by this invention has good application prospects in the fields of cover plates for consumer electronics products, central control screens and dashboards for automobiles, and precision optical windows.

[0043] The above description is merely an example and illustration of the concept of this application. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the inventive concept or exceed the scope defined in the claims, they should all fall within the protection scope of this application.

Claims

1. A high-hardness high-crack-resistance aluminoborosilicate glass-ceramic, characterized in that, This high-hardness, high-crack-resistant aluminoborosilicate microcrystalline glass is composed of the following raw materials in the following molar percentages: Al2O3 30-36%, B2O3 20-28%, SrO 8-12%, Li2O 1-3%, P2O5 0.5-2%, La2O3 8-10%, with the remainder being SiO2.

2. The high-hardness, high-crack-resistant aluminoborosilicate microcrystalline glass according to claim 1, characterized in that, The molar ratio of Al2O3 to the sum of the moles of SrO, Li2O, and La2O3 is ≥1.

5.

3. A method for preparing high-hardness, high-crack-resistant aluminoborosilicate microcrystalline glass as described in any one of claims 1-2, characterized in that, Includes the following steps: S1. Weigh the raw materials according to the formula, mix and stir, melt and treat, cast and mold, anneal and treat to obtain the base glass; S2. The base glass is subjected to programmed temperature-controlled crystallization treatment and cooled to obtain a high-hardness, high-crack-resistant aluminoborosilicate microcrystalline glass.

4. The method for preparing a high-hardness, high-crack-resistant aluminoborosilicate microcrystalline glass according to claim 3, characterized in that, The mixing and stirring are carried out at a speed of 200-300 rpm for 3-4 hours.

5. The method for preparing a high-hardness, high-crack-resistant aluminoborosilicate microcrystalline glass according to claim 3, characterized in that, The melting process is carried out at a melting temperature of 1600-1625℃ for 2-4 hours.

6. The method for preparing a high-hardness, high-crack-resistant aluminoborosilicate microcrystalline glass according to claim 3, characterized in that, The annealing process is carried out at a temperature of 550-600℃ for 1-3 hours.

7. The method for preparing a high-hardness, high-crack-resistant aluminoborosilicate microcrystalline glass according to claim 3, characterized in that, The programmed temperature control raises the temperature from room temperature to 780-840℃ at a rate of 1-10℃ / min, and holds the temperature at that temperature for 2-6 hours.

8. The method for preparing a high-hardness, high-crack-resistant aluminoborosilicate microcrystalline glass according to claim 3, characterized in that, The cooling process involves cooling the material to room temperature at a rate of 1-2°C / min.

9. The method for preparing a high-hardness, high-crack-resistant aluminoborosilicate microcrystalline glass according to claim 3, characterized in that, The high-hardness, high-crack-resistant aluminum borosilicate microcrystalline glass has a crystallinity of 40%-60%, and its main crystalline phases include SrB2O4 and Al5BO9.

Images