Microcrystalline glass, strengthened microcrystalline glass and terminal

Abstract

The application provides a microcrystalline glass, wherein a crystal phase in the microcrystalline glass comprises a sodium-containing nepheline phase, a forsterite crystal phase and a TiO2 crystal phase, wherein the sodium-containing nepheline phase comprises one or more of sodium nepheline and a silica solid solution thereof, a sodium-potassium solid solution nepheline and a silica solid solution thereof; and the TiO2 crystal phase comprises at least one of an anatase phase and a rutile phase. The microcrystalline glass containing the above crystal phase has high light transmittance, can be efficiently ion exchanged to obtain a strengthened microcrystalline glass containing a hexagonal potassium nepheline crystal phase on the surface, and has high hardness and good drop resistance, and can meet the application requirements of large-size, ultrathin terminal glass cover plates and the like. The application also provides a strengthened microcrystalline glass obtained by strengthening the microcrystalline glass, and a terminal adopting the strengthened microcrystalline glass.

Description

Technical Field

[0001] This application relates to the field of glass preparation technology, and in particular to a microcrystalline glass, a reinforced microcrystalline glass, and a terminal. Background Technology

[0002] Currently, the demand for larger and thinner screens in smartphones, tablets, and other terminal products is becoming increasingly prominent, placing higher demands on the drop resistance of glass covers. Traditional mobile phone cover glass uses ordinary aluminosilicate glass, and simply strengthening processes such as secondary ion exchange can no longer significantly improve its strength, and therefore cannot effectively improve its drop resistance. Therefore, it is necessary to develop new glass with superior drop resistance to meet the application requirements of large-size, ultra-thin cover glass. Summary of the Invention

[0003] This application provides a microcrystalline glass with high transparency and high strength. It can be easily and efficiently strengthened by ion exchange, and has a large ion exchange layer depth, high surface compressive stress after strengthening, and excellent drop resistance. This microcrystalline glass can meet the application requirements of large-size, ultra-thin glass covers, etc.

[0004] Specifically, the first aspect of this application provides a glass-ceramic, which comprises a glass phase and a crystalline phase. The crystalline phase includes a sodium-containing nepheline phase, a forsterite crystalline phase, and a TiO2 crystalline phase. The sodium-containing nepheline phase includes one or more of sodium nepheline and its silica solid solution, and sodium-potassium nepheline and its silica solid solution. The TiO2 crystalline phase includes at least one of anatase and rutile phases. These crystalline phases, together with the glass phase, form a dense structure, giving the glass-ceramic excellent mechanical strength, extremely low dielectric constant, and maintaining high visible light transmittance and ion exchange capacity. This makes it particularly suitable for use in large-size, ultra-thin cover plates for terminal products with communication functions.

[0005] In this embodiment, the crystal size of at least one of the sodium nepheline phase, forsterite phase, and TiO2 phase is less than or equal to 80 nm. A crystal size ≤80 nm is much lower than the wavelength of visible light, thus allowing the glass-ceramic to have high transmittance.

[0006] In this embodiment of the application, the microcrystalline glass comprises the following components, in molar percentage:

[0007] SiO2: 50%-66%,

[0008] Al2O3: 8%-15%,

[0009] Na2O: 8%-15%,

[0010] Li2O: 3%-6%,

[0011] K2O: 1%-3%,

[0012] MgO: 6%-14%,

[0013] CaO: 0-3%,

[0014] SrO: 0-3%,

[0015] BaO: 0-3%,

[0016] ZnO: 0-5%,

[0017] TiO2: 1%-5%;

[0018] The ratio of [Li2O+Na2O+K2O+MgO+CaO] / Al2O3 is 2.0-3.11;

[0019] The ratio of [Li₂O+Na₂O+K₂O] / [MgO+CaO] is 0.8-1.86;

[0020] The ratio of [(Li2O+Na2O+K2O)-Al2O3] / TiO2 is 0-6.0. The microcrystalline glass of this application, through reasonable control of its components and proportions, not only allows the precipitation of the aforementioned sodium-containing nepheline phase, forsterite phase, and TiO2 phase within the glass, thus improving its strength, but also enables efficient ion exchange, resulting in a deeper compressive stress layer and higher surface compressive stress. This secondary enhancement of the glass's strength ultimately yields excellent drop resistance and impact resistance.

[0021] In some embodiments of this application, the molar percentage of Li2O is 4%-5%. An appropriate amount of Li2O can enable microcrystalline glass to achieve a greater ion exchange depth through a two-step ion exchange process, thereby improving the glass's resistance to drops from rough surfaces.

[0022] In some embodiments of this application, 25% ≤ Li2O / Na2O ≤ 50%. A suitable Li2O / Na2O ratio is beneficial for simultaneously increasing the depth of the ion exchange layer and improving deep layer stress, thereby enhancing drop resistance.

[0023] In some embodiments of this application, the molar percentage of Al2O3 is 9%-13%. A relatively high Al2O3 content is beneficial for improving the strength and ion exchange capacity of the glass without increasing the difficulty of glass manufacturing.

[0024] In some embodiments of this application, the ratio of [(Li2O+Na2O+K2O)-Al2O3] / TiO2 is 0.25-1.25. This ratio allows the glass-ceramic to have a suitable proportion of uniformly distributed crystalline phases, maintaining high light transmittance.

[0025] In some embodiments of this application, the molar percentage of MgO is 8%-12%. An appropriate amount of MgO can reduce the melting temperature of the glass, reduce its viscosity, and increase its Young's modulus.

[0026] In some embodiments of this application, the ratio of [Li₂O+Na₂O+K₂O] / [MgO+CaO] is 0.92-1.45. This ratio ensures that the glass-ceramic contains a suitable proportion of sodium-containing nepheline phase and forsterite phase, giving the glass-ceramic high hardness and ion exchange capacity.

[0027] In some embodiments of this application, the molar percentage of ZnO is 1%-4%. An appropriate amount of ZnO can also reduce the melting temperature of the glass, reduce its viscosity, and increase its Young's modulus.

[0028] In some embodiments of this application, the sum of the molar percentages of CaO, SrO, and BaO is less than or equal to 6%. Controlling the oxides of divalent metal ions with larger ionic radii to a lower range can reduce difficulties in glass melting while minimizing adverse effects on subsequent ion exchange.

[0029] In some embodiments of this application, the molar percentage of TiO2 is 2%-4%. As a nucleating agent, an appropriate content of TiO2 is beneficial for obtaining more fine grains during the crystallization process, and can promote the growth of sodium-containing nepheline phase and high-strength forsterite phase, thereby improving the mechanical properties of the glass.

[0030] In this embodiment of the application, the visible light transmittance of the microcrystalline glass with a thickness of ≤1mm is greater than or equal to 85%. The high transmittance allows the microcrystalline glass to meet the optical requirements for display and shooting when used as a display screen cover and camera protective cover for terminal products.

[0031] The microcrystalline glass provided in the first aspect of this application has high strength and visible light transmittance, and can undergo efficient ion exchange to obtain a high ion exchange layer depth and a large surface compressive stress, thereby enhancing the glass strength and effectively improving its drop resistance.

[0032] This application also provides a reinforced glass-ceramic, comprising the aforementioned glass-ceramic and a compressive stress layer on the surface of the glass-ceramic, wherein the compressive stress layer contains a hexagonal potassium nepheline crystal phase. This reinforced glass-ceramic is obtained by ion exchange of the aforementioned glass-ceramic.

[0033] In this embodiment, the crystal size of at least one of the sodium-containing nepheline phase, forsterite phase, TiO2 phase, and hexagonal potassium nepheline phase is less than or equal to 80 nm. A crystal size ≤80 nm is far below the visible light wavelength range, thus allowing the reinforced glass-ceramic to have high transmittance.

[0034] In this embodiment, the depth of the compressive stress layer of the reinforced microcrystalline glass is greater than or equal to 50 μm. The surface compressive stress of the reinforced microcrystalline glass is greater than or equal to 800 MPa. Higher ion exchange layer depth and surface compressive stress can significantly improve the glass's drop resistance.

[0035] The reinforced microcrystalline glass provided in the second aspect of this application has high transmittance and a high compressive stress layer depth. The hexagonal potassium nepheline crystal phase it contains helps to achieve greater surface compressive stress, resulting in stronger mechanical properties and thus stronger drop resistance. This reinforced microcrystalline glass is not only suitable for electronic information terminal products, but also for transportation, construction, and other fields. Specifically, it can be used for protective glass in vehicles, household appliances, and buildings, such as protective glass for displays and dashboards.

[0036] This application embodiment also provides a reinforced microcrystalline glass, which comprises the following components by molar percentage:

[0037] SiO2: 50%-66%,

[0038] Al2O3: 8%-15%,

[0039] Na2O: 8%-15%,

[0040] Li2O: 3%-6%,

[0041] K2O: 1%-3%,

[0042] MgO: 6%-14%,

[0043] CaO: 0-3%,

[0044] SrO: 0-3%,

[0045] BaO: 0-3%,

[0046] ZnO: 0-5%,

[0047] TiO2: 1%-5%;

[0048] The ratio of [Li2O+Na2O+K2O+MgO+CaO] / Al2O3 is 2.0-3.11;

[0049] The ratio of [Li₂O+Na₂O+K₂O] / [MgO+CaO] is 0.8-1.86;

[0050] The ratio of [(Li2O+Na2O+K2O)-Al2O3] / TiO2 is 0-6.0.

[0051] In this embodiment of the application, the crystalline phases in the reinforced glass-ceramic include sodium-containing nepheline phase, forsterite phase, TiO2 phase, and hexagonal potassium nepheline phase, and the hexagonal potassium nepheline phase is only distributed on the surface of the reinforced glass-ceramic; wherein, the sodium-containing nepheline phase includes one or more of sodium nepheline and its silica solid solution, sodium-potassium solid solution nepheline and its silica solid solution; the TiO2 phase includes at least one of anatase phase and rutile phase.

[0052] In this embodiment, the reinforced microcrystalline glass has a compressive stress layer on both opposite sides, and the depth of the compressive stress layer is greater than or equal to 50 μm; the hexagonal potassium nepheline crystal phase is located in the compressive stress layer.

[0053] The reinforced microcrystalline glass provided in the third aspect of this application, by reasonably controlling the composition and composition ratio, can contain the above-mentioned sodium-containing nepheline phase, forsterite crystal phase, TiO2 crystal phase and hexagonal potassium nepheline crystal phase inside the glass. The reinforced microcrystalline glass has high visible light transmittance, high strength, as well as a deep compressive stress layer and high surface compressive stress, thereby ultimately obtaining excellent drop resistance, impact resistance and so on.

[0054] This application also provides a terminal, including a housing assembled on the outside of the terminal and a circuit board located inside the housing, the housing being made of the aforementioned reinforced microcrystalline glass.

[0055] The terminal provided in this application embodiment has a casing made of reinforced microcrystalline glass, which has better drop resistance and can improve the reliability and competitiveness of the terminal product.

[0056] In this embodiment, the thickness of the reinforced microcrystalline glass is 0.4mm-2mm. Thinner reinforced microcrystalline glass can meet market demand for ultra-thin glass covers, etc.

[0057] In one embodiment of this application, the outer casing may include a display screen cover assembled on the front side of the terminal, the display screen cover being made of the aforementioned reinforced microcrystalline glass. In another embodiment of this application, the outer casing may also include a rear cover assembled on the rear side of the terminal, the rear cover being made of the aforementioned reinforced microcrystalline glass. In some other embodiments of this application, the terminal may further include a camera assembly located inside the outer casing, the outer casing may include a camera protective cover, the camera protective cover being disposed on the camera assembly, the camera protective cover being made of the aforementioned reinforced microcrystalline glass. In the embodiments of this application, the outer casing may be partially or entirely made of reinforced microcrystalline glass. In the embodiments of this application, the terminal may have one or more of the display screen cover, rear cover, and camera protective cover made of the aforementioned reinforced microcrystalline glass. Attached Figure Description

[0058] Figure 1 This is a schematic diagram of the front structure of a terminal provided in an embodiment of this application;

[0059] Figure 2 A schematic diagram of the rear structure of a terminal provided in an embodiment of this application;

[0060] Figure 3 The XRD patterns of the glass-ceramics obtained after subjecting the precursor glass of Embodiment 1 of this application to different heat treatments are shown.

[0061] Figure 4 This is an electron microscope image of the microcrystalline glass obtained after heat treatment at 650°C for 2 hours in Example 1 of this application. Detailed Implementation

[0062] The embodiments of this application are described below with reference to the accompanying drawings.

[0063] See Figure 1 and Figure 2 This application provides a terminal 100, which can be a mobile phone, tablet computer, virtual reality (VR) terminal device, smart wearable product, or other electronic product. The terminal 100 includes a housing assembled on the outside of the terminal and a circuit board located inside the housing. The housing includes a display screen cover 101 assembled on the front and a rear cover 102 assembled on the rear. The display screen cover 101 covers the display module. The display screen cover 101 and / or the rear cover 102 are made of the reinforced microcrystalline glass provided in this application. In this application embodiment, the display screen cover 101 and the rear cover 102 can be entirely made of reinforced microcrystalline glass, or only partially made of reinforced microcrystalline glass. In this application embodiment, the display screen cover 101 can be a protective cover disposed on a touch screen.

[0064] In some embodiments of this application, such as Figure 2 As shown, the terminal 100 includes a camera assembly 2 located inside a housing. The housing may include a camera protective cover 103, which covers the camera assembly 2. The camera protective cover 103 is made of reinforced microcrystalline glass. In this embodiment, the camera protective cover 103 may be partially or entirely made of reinforced microcrystalline glass. In this embodiment, the location of the camera protective cover 103 depends on the location of the camera assembly 2; it may be located on the front or rear side of the terminal 100. In some embodiments of this application, the camera protective cover 103 may be a separate structure from the display cover 101 or the rear cover 102. In other embodiments of this application, the camera protective cover 103 may be an integral structure with the display cover 101 or the rear cover 102.

[0065] In this embodiment of the application, the display screen cover 101, back cover 102, and camera protective cover 103 in the terminal 100 can be made of reinforced microcrystalline glass, any two of them can be made of reinforced microcrystalline glass, or all three can be made of reinforced microcrystalline glass. Reinforced microcrystalline glass has excellent drop resistance and high transmittance, which can improve the reliability of the terminal product and meet the optical requirements of the display screen cover and camera protective cover for display and shooting.

[0066] In this application embodiment, the thickness of the reinforced microcrystalline glass used as the display screen cover 101, back cover 102, and camera protective cover 103 can be 0.4mm-2mm. In some embodiments of this application, the thickness of the reinforced microcrystalline glass can also be 0.5mm-1mm, 0.6mm-1mm, or 0.6-0.8mm. This reinforced microcrystalline glass can be molded into 2D or 2.5D planar products, or into 3D curved products.

[0067] The reinforced glass-ceramic provided in this application can be obtained by ion exchange of the following glass-ceramic. The reinforced glass-ceramic and the glass-ceramic have the same chemical composition, but their crystal structures are slightly different, which will be described in detail below.

[0068] The microcrystalline glass provided in this application includes a glass phase and a crystalline phase, wherein the crystalline phase includes a sodium-containing nepheline phase, a forsterite crystalline phase, and a TiO2 crystalline phase; the sodium-containing nepheline phase includes one or more of sodium nepheline and its silica solid solution, sodium-potassium solid solution nepheline and its silica solid solution; the TiO2 crystalline phase includes at least one of anatase phase and rutile phase.

[0069] The aforementioned crystalline phases can co-form a dense structure with the glassy phase, giving the glass-ceramic excellent mechanical strength and a suitable melting temperature, while maintaining high visible light transmittance and ion exchange capacity. The presence of the TiO2 crystalline phase facilitates the growth of sodium-containing nepheline and forsterite crystalline phases during the crystallization process of glass-ceramic formation. The presence of the sodium-containing nepheline phase allows for more efficient ion exchange strengthening of the glass-ceramic, resulting in a deeper and more surface-compressive stress layer (i.e., the CS layer), further enhancing its surface hardness and drop resistance. The forsterite crystalline phase has high hardness, contributing to the glass-ceramic's high hardness and extremely low dielectric constant, making it suitable for applications in communication-enabled terminal products.

[0070] In this embodiment, compared to the forsterite and TiO2 crystal phases, the sodium-containing nepheline phase is the main crystalline phase, and its crystallization temperature is lower, which allows for a lower melting temperature for forming the glass-ceramic. The forsterite crystal phase is typically formed at a higher temperature than the sodium-containing nepheline phase. The TiO2 crystal phase is typically formed at a lower temperature than the sodium-containing nepheline phase.

[0071] In some embodiments of this application, the chemical formula of the forsterite crystal phase can be represented as Mg₂SiO₄. The chemical formula of sodium nepheline can be represented as NaAlSiO₄; the chemical formula of sodium-potassium solid solution nepheline can be represented as (Na,K)AlSiO₄, where Na is dominant relative to K. The silica solid solution of sodium nepheline can be represented as NaAlSiO₄-SiO₂, and the silica solid solution of sodium-potassium solid solution nepheline can be represented as (Na,K)AlSiO₄-SiO₂, both of which belong to nepheline solid solutions.

[0072] In some embodiments of this application, the crystalline phase in the aforementioned glass-ceramic may further include at least one of β-nepheline (β-LiAlSiO4), γ-nepheline (γ-LiAlSiO4), and β-spodumene (Li2O·Al2O3·4SiO2). The presence of these crystalline phases can adjust the coefficient of thermal expansion of the glass-ceramic and improve its thermal shock resistance.

[0073] In this embodiment, at least one of the sodium-containing nepheline phase, forsterite phase, and TiO2 phase has a crystal size in the nanometer range, for example, less than or equal to 80 nm. That is, any one of the sodium-containing nepheline phase, forsterite phase, and TiO2 phase may have a nanometer-scale crystal size, any two of them may have a nanometer-scale crystal size, or all three may have a nanometer-scale crystal size. An 80 nm grain size is far below the visible light wavelength range, allowing the glass-ceramic to have high visible light transmittance. In some embodiments, the crystal size of at least one of the crystal phases is ≤70 nm, ≤60 nm, ≤50 nm, ≤40 nm, ≤30 nm, ≤20 nm, or ≤10 nm. In some embodiments, approximately 60% or more of the crystal phases in the glass-ceramic have crystal sizes in the aforementioned nanometer range.

[0074] In this embodiment, the visible light transmittance of the microcrystalline glass with a thickness ≤1mm is greater than or equal to 85%. The spectral range of visible light is generally 390nm-700nm. Microcrystalline glass with high transmittance has high transparency and is more suitable for use as display screen cover glass and camera protective cover glass to meet the optical requirements of display and imaging. In some embodiments, the visible light transmittance of the microcrystalline glass with a thickness ≤1mm is greater than or equal to 90%.

[0075] The microcrystalline glass of this application embodiment comprises the following components, by molar percentage:

[0076] SiO2: 50%-66%,

[0077] Al2O3: 8%-15%,

[0078] Na2O: 8%-15%,

[0079] Li2O: 3%-6%,

[0080] K2O: 1%-3%,

[0081] MgO: 6%-14%,

[0082] CaO: 0-3%,

[0083] SrO: 0-3%,

[0084] BaO: 0-3%,

[0085] ZnO: 0-5%,

[0086] TiO2: 1%-5%;

[0087] The ratio of [Li2O+Na2O+K2O+MgO+CaO] / Al2O3 is 2.0-3.11;

[0088] The ratio of [Li₂O+Na₂O+K₂O] / [MgO+CaO] is 0.8-1.86;

[0089] The ratio of [(Li2O+Na2O+K2O)-Al2O3] / TiO2 is 0-6.0.

[0090] The microcrystalline glass of this application, through reasonable control of its components and proportions, not only allows the precipitation of the aforementioned sodium-containing nepheline, forsterite, and TiO2 crystalline phases within the glass, but also enhances its strength. Furthermore, it enables efficient ion exchange, resulting in a deeper compressive stress layer and higher surface compressive stress, thus further strengthening the glass and ultimately achieving excellent drop resistance and impact resistance. The addition of a certain amount of Li2O allows the microcrystalline glass to achieve a greater ion exchange depth through a two-step ion exchange process, improving its resistance to drops from rough surfaces. A certain amount of Na2O participates in the crystallization of the sodium-containing nepheline phase and can also control the degree of subsequent ion exchange, resulting in greater surface compressive stress, improved impact resistance, and a lower melting temperature, facilitating processing and molding at lower temperatures. A certain amount of MgO can ensure the precipitation of the harder magnesium olivine crystal phase, thereby increasing the hardness of the glass and giving it a suitable liquidus temperature. It will not reduce the migration rate of alkali metal ions during the ion exchange process of the glass-ceramic, thus ensuring a suitable ion exchange rate.

[0091] In addition, to ensure that the glass-ceramic contains appropriate proportions of the aforementioned crystalline phases, to ensure that the glass-ceramic as a whole has a dense network structure and high visible light transmittance, and to enable efficient ion exchange, the following conditions must be met: the ratio of [Li2O+Na2O+K2O+MgO+CaO] / Al2O3 is 2.0-3.11, the ratio of [(Li2O+Na2O+K2O)-Al2O3] / TiO2 is 0-6.0, and the ratio of [Li2O+Na2O+K2O] / [MgO+CaO] is 0.8-1.86.

[0092] The term "ion exchange" used in this application refers to what is commonly known as chemical intensification. Its main principle is to transfer larger ions (such as K+) from a molten salt into the ion exchange medium. + Na + ) and smaller ions in glass (such as Na) + Li + The ion exchange layer forms a compressive stress layer on the surface through the "squeezing effect," creating an ion exchange layer (i.e., a compressive stress layer) of a certain depth. Even if external forces cause cracks on the glass surface, the presence of the ion exchange layer can effectively prevent the cracks from propagating, greatly improving the glass's resistance to external forces and significantly increasing its strength.

[0093] In this application, SiO2 is the backbone component of the glass network structure, and its content directly affects the glass's properties, such as its chemical stability, mechanical strength, and crystal composition. Generally, the higher the SiO2 content, the better the connectivity of the glass network structure, the higher the glass density, and the stronger the mechanical properties. However, pure SiO2 glass has a high melting point, which increases the glass's melting temperature. Other network modifiers and fluxes need to be added to prepare economically viable glass. Considering all these factors, the molar content of SiO2 in this application is controlled at 50%-66%. Specifically, in some embodiments of this application, the molar content of SiO2 can be 55%-61%, and in other embodiments, it can be 56%-60%.

[0094] In this embodiment, Al2O3 is a network intermediate oxide that can participate in the glass network structure, affecting the glass's mechanical strength, chemical stability, and durability. It can also control the amount and ease of nepheline crystal precipitation. When the alkali metal ion oxide R2O (R being Li, Na, or K, etc.) in the glass is greater than or equal to Al2O3, i.e., R2O ≥ Al2O3, the alkali metal ions play a role in charge balance, making aluminum ions (Al2O3) more stable. 3+ Al₂O₃ is in tetracoordinate, forming AlO₄ tetrahedra and participating in the network structure. Since the volume of [AlO₄] tetrahedra is larger than that of [SiO₄] tetrahedra, it can increase the network porosity, making it easier for exchanged ions to move. Therefore, this tetrahedron can greatly improve the ion exchange capacity of glass-ceramics. However, with the continued increase of Al₂O₃ content, Al… 3+ Ions may exist in 5- or even 6-coordinate forms, strengthening the network structure, which can adversely affect ion exchange. Furthermore, excessively high Al₂O₃ content can lead to difficulties in melting during glass preparation (i.e., a higher liquidus temperature) and a lower liquidus viscosity. Therefore, considering all factors, the molar content of Al₂O₃ in this application is controlled within the range of 8%-15%. Specifically, in some embodiments of this application, the molar content of Al₂O₃ can be 9%-13%, and in other embodiments, it can be 10%-12%. In still other embodiments, the molar content of Al₂O₃ can be 8%-9%.

[0095] Furthermore, considering that the amounts of alkali metal oxides R2O and alkaline earth metal oxides such as MgO and CaO, as well as the degree of difference between R2O and Al2O3, affect the solubility of tetravalent oxides (such as TiO2 and SnO2) in the glass melt, this application controls the ratio of [Li2O+Na2O+K2O+MgO+CaO] / Al2O3 to 2.0-3.11 and the ratio of [(Li2O+Na2O+K2O)-Al2O3] / TiO2 to 0-6.0. This allows the tetravalent oxides (such as TiO2 and SnO2) in the glass melt to have good solubility, enabling TiO2 to be uniformly distributed in the glass-ceramic during crystallization, preventing local agglomeration from reducing the transparency of the glass, and giving the glass a dense and uniform network structure. In addition, it also allows the glass-ceramic to have a suitable proportion of the above-mentioned crystalline phases, resulting in a high overall light transmittance and a suitable liquidus temperature. In some embodiments of this application, the ratio of [(Li2O+Na2O+K2O)-Al2O3] / TiO2 can be 0.1-2.5, and in other embodiments, the ratio can be 0.25-1.25.

[0096] In this application, Li₂O and Na₂O are the main network modifiers, providing excess oxygen and acting as a network disruptor, thereby reducing the density and chemical stability of the glass. The introduction of Li₂O and Na₂O can also reduce high-temperature viscosity, acting as a flux. Furthermore, Li₂O and Na₂O are the main carriers for ion exchange, and their content directly affects the ion exchange process. In the embodiments of this application, the molar content of Li₂O is controlled at 3%-6%. Specifically, the molar content of Li₂O can be 3%, 3.5%, 4%, 4.5%, 5%, or 6%. In some embodiments, the molar content of Li₂O can be 3%-5%, 4%-5%, or 3%-4.5%. In some embodiments, the addition of Li₂O can also lead to the precipitation of nepheline and / or spodumene crystal phases to adjust the coefficient of thermal expansion of the glass-ceramic within a suitable range and improve its thermal shock resistance.

[0097] A higher Na₂O content helps increase K + / Na + Increased ion exchange capacity facilitates the formation of higher surface compressive stress, and increased Na₂O content also makes the precipitation of sodium-containing nepheline phase easier. However, the Na content in the glass... +Excessive Na₂O content can actually inhibit crystallization. Controlling the molar content of Na₂O between 8% and 15% can effectively reduce the melting temperature of the glass, regulate the liquidus viscosity appropriately, and simultaneously achieve better results in subsequent chemical strengthening while minimizing the inhibition of crystallization. Specifically, the molar content of Na₂O can be 8%, 9%, 10%, 11%, 12%, 13%, or 14%. In some embodiments, the molar content of Na₂O can be 10%-13%, 8%-11%, or 8%-9%.

[0098] An appropriate amount of Li₂O can enable the surface of the glass-ceramic to achieve a greater ion exchange depth through the first step of Na-Li ion exchange, thus improving the glass's resistance to drops from rough surfaces. Conversely, an appropriate amount of Na₂O can enable the surface of the glass-ceramic to achieve greater surface compressive stress through the second step of K-Na ion exchange, thereby improving the glass's impact resistance. In the embodiments of this application, considering both surface compressive stress and ion exchange layer depth, the Li₂O / Na₂O ratio is controlled to be 25% ≤ Li₂O / Na₂O ≤ 50%, thereby enabling the strengthened glass-ceramic to have higher resistance to crack formation and improved drop resistance.

[0099] K₂O can lower the melting temperature of glass, which is beneficial for melting and forming, and improves melt quality and optical properties. However, excessive K₂O content can reduce crystallization properties and affect the strength of the glass. With a fixed R₂O content, appropriately increasing K₂O can improve the chemical stability of the glass and effectively support its properties. In some embodiments, the molar content of K₂O can be 1%-2% or 2%-3%. In some embodiments of this application, the molar content of R₂O in the glass-ceramic can be 12%-24%, 13%-22%, or 15%-22%.

[0100] Furthermore, the K₂O content can also regulate the degree of transformation from sodium nepheline to hexagonal potassium nepheline during ion exchange in the glass-ceramic, thereby obtaining a larger surface compressive stress. In some embodiments of this application, when 5% ≤ K₂O / Na₂O ≤ 50%, the glass can obtain an ideal ion exchange rate and degree of ion exchange. In some embodiments of this application, to ensure that the glass-ceramic contains a suitable proportion of the aforementioned sodium nepheline phase and forsterite crystal phase, the ratio of [Li₂O+Na₂O+K₂O] / [MgO+CaO] can be controlled to be 0.92-1.45.

[0101] In this application, MgO is an essential component for the precipitation of the hard forsterite phase, which is beneficial for improving the hardness of the glass. During glass melting, MgO also helps to reduce the melting viscosity and melting temperature. Furthermore, due to the relatively small ionic radius of Mg ions, an appropriate amount of MgO can improve stress relaxation, increase Young's modulus, and enhance the density and chemical stability of the glass structure during ion exchange, while minimizing its negative impact on the diffusion rate of alkali metal ions. However, excessively high MgO content will result in an excessively high proportion of the forsterite phase in the glass-ceramic, drastically increasing its liquidus temperature, which is detrimental to subsequent processing. In this application, the molar content of MgO is controlled at 6-14%, ensuring a suitable liquidus temperature for the glass without reducing the migration rate of alkali metal ions during ion exchange. In some embodiments, the molar content of MgO can be 7%-13%, 8%-12%, or 6%-9%.

[0102] Similar to MgO, ZnO also acts as a flux during glass melting, lowering the melting temperature. Furthermore, during ion exchange, an appropriate amount of ZnO can improve stress relaxation and increase Young's modulus in glass with minimal negative impact on the diffusion rate of alkali metal ions. However, excessive ZnO content may lead to the precipitation of zinc spinel (ZnAl₂O₄) or zinc silicospermite (Zn₂SiO₄), resulting in a sharp increase in the liquidus temperature of the glass. Considering these effects, the molar content of ZnO in this application is controlled at 0-5%. In some embodiments of this application, the molar content of ZnO can be 0-4%, 0%-3%, 0%-2%, 1%-3%, or 1%-2%. In some embodiments, the divalent metal oxide in the glass-ceramic can be only MgO, or only MgO and ZnO, to minimize the adverse effects during subsequent ion exchange of the glass-ceramic.

[0103] In some embodiments of this application, the glass-ceramic may include one or more of CaO, SrO, and BaO as a flux to lower the melting temperature of the glass, facilitating glass melting and improving its thermal and chemical stability. However, their presence reduces the migration rate of alkali metal ions during ion exchange, which is detrimental to the ion exchange process. Therefore, their total content is less than or equal to 6%. In some embodiments, CaO+SrO+BaO ≤ 5%, ≤ 4%, ≤ 3%, ≤ 2%, or ≤ 1%. In other embodiments, when the aforementioned three compounds are present in the glass-ceramic, the content of any one of CaO, SrO, and BaO does not exceed 2%, preferably not more than 1%.

[0104] In this embodiment, TiO2 is used as a nucleating agent for glass-ceramics. It is self-nucleating and, when used in conjunction with nucleating agents such as MgO, can increase the content of magnesium olivine phase and sodium-containing nepheline phase in the glass-ceramics, resulting in finer grains and enhanced mechanical properties. However, excessive TiO2 content can cause glass coloration, affecting its transparency. Considering these effects, the molar content of TiO2 in this embodiment is controlled at 1%-5%. This satisfies the requirement for enhanced nucleation without causing significant coloration, and also ensures a suitable liquidus viscosity for the glass. In some embodiments, the molar content of TiO2 is 2%-4%, 3%-4%, or 2%-3.5%.

[0105] In addition, to achieve better melting results (e.g., reducing bubbles, streaks, etc.), in some embodiments of this application, a certain amount of clarifying agent can be added to the above-mentioned oxides in a 100% molar ratio. The molar percentage of the clarifying agent relative to the total amount of various oxides can not exceed 3% to avoid affecting the dissolution of TiO2. In some embodiments, the amount of clarifying agent can not exceed 2% or 1.2%. Specifically, the clarifying agent can be, but is not limited to, sulfates (such as Glauber's salt), chlorides (such as sodium chloride), antimony trioxide (Sb2O3), tin dioxide (SnO2), etc., and the selection of clarifying agent can be one or a combination of them.

[0106] In some embodiments of this application, the aforementioned glass-ceramic may further contain oxides of transition metals such as Co, Cr, Cu, Mn, Sb, Bi, Ni, V, and Se, rare earth elements, and colorants known in the art that can impart a certain color to the glass-ceramic. In some cases, the glass-ceramic may also contain any impurities introduced during the manufacturing process, with the impurity content not exceeding 0.15% by molar percentage.

[0107] Accordingly, embodiments of this application also provide a method for preparing the above-mentioned microcrystalline glass, including:

[0108] The raw materials corresponding to each component are mixed according to the ratio. The resulting precursor glass composition is melted, shaped, and annealed to obtain the precursor glass. The precursor glass is then heat-treated to crystallize it, thus obtaining the microcrystalline glass.

[0109] Although the components in glass-ceramics are expressed in terms of oxides, in actual preparation, the aforementioned raw materials can be other materials containing these oxides. For example, the aforementioned SiO2 can be silica sand, the aforementioned Al2O3 can be cerium monoxide, the aforementioned Na2O can be Na2CO3, and the aforementioned MgO can be dolomite. The aforementioned SiO2, Al2O3, Na2O, ZnO, and MgO can all be added together in the form of aluminosilicate glass. The key is to ensure that the proportions of these materials, when converted to oxides, meet the aforementioned oxide proportion requirements.

[0110] In this application, the melting of glass typically includes processes such as melting various raw materials to form molten glass, clarifying the molten glass, homogenizing the molten glass, and cooling the molten glass. In the embodiments of this application, the melting temperature used in the preparation of microcrystalline glass is relatively low, which can be less than or equal to 1620°C, for example, less than or equal to 1580°C or less than or equal to 1550°C. In some embodiments of this application, the melting temperature can be less than or equal to 1540°C, and more specifically, it can be 1500-1540°C.

[0111] In some embodiments of this application, the precursor glass composition exhibits a liquidus temperature of less than or equal to 1400°C, facilitating its processing into a glass body. Here, the term "liquidus temperature" refers to the highest temperature at which an object begins to change from a liquid to a solid state, specifically during the cooling phase. In some embodiments, the liquidus temperature exhibited by the precursor glass composition may be ≤1300°C, ≤1200°C, ≤1100°C, ≤1000°C, or ≤900°C. In some embodiments of this application, the precursor glass composition exhibits a liquidus viscosity of ≥20 kPa·s. Here, the term "liquidus viscosity" refers to the viscosity at the liquidus temperature. In some embodiments, the liquidus viscosity exhibited by the precursor glass composition may be ≥25 kPa·s, ≥30 kPa·s, ≥35 kPa·s, ≥40 kPa·s, ≥50 kPa·s, or ≥100 kPa·s.

[0112] The process of transforming molten glass into a geometrically shaped product at a specific furnace temperature. The microcrystalline glass of this application is prepared using conventional forming conditions. For example, it can be formed using processes such as rolling, casting, float glass, overflow glass, pull glass, and roller glass. The purpose of annealing after forming is to minimize or eliminate thermal stress generated in the glass. In the embodiments of this application, the annealing temperature can be 450℃-600℃. The resulting precursor glass can be a flat sheet or have a certain three-dimensional shape.

[0113] Heat treatment of the precursor glass is performed to crystallize it, producing a predetermined crystalline phase and glassy phase. Once the composition is determined, the crystal composition and properties of the glass-ceramic primarily depend on the heat treatment process. The heat treatment can be completed in one step or two steps. A one-step heat treatment process may involve heating the sample to a temperature near or higher than the crystallization temperature and holding it at that temperature for a certain time to allow for sufficient crystal growth. In some embodiments of this application, the holding temperature for the one-step heat treatment can be 580-1050℃, for example, 600, 650, 700, 750, 800, 850, 900, 950, or 1000℃, and more specifically, 600-1000℃, 650-950℃, 700-900℃, or 750-850℃. The heating rate from room temperature to this holding temperature can be 1-20℃ / min, for example, 2-10℃ / min. The holding time for one-step heat treatment can be 0.25h-12h, for example, 0.5, 1, 2, 3, 4, 5, 6 or 8h. In some embodiments, the holding time can be 0.25-8h, 0.5-6h or 1-5h.

[0114] The specific process of the two-step heat treatment can be as follows: first, heat the sample to the nucleation temperature T. n The glass is then kept at this temperature for a certain period of time to allow crystal nuclei to fully form before being heated to the crystallization temperature T. c The crystals were kept near the surface and heated for a certain period of time to allow them to grow; then they were cooled to room temperature. Among them, T... c Greater than T n In some embodiments of this application, T n It can be 580-850℃, T c The temperature can be 650-1000℃. The holding time for nucleation and crystallization can each be in the range of 0.25h-6h.

[0115] The method for preparing the microcrystalline glass provided in this application is simple and suitable for industrial production.

[0116] This application also provides a reinforced glass crystal, which can be obtained by ion exchange of the aforementioned glass crystal. This reinforced glass crystal can also be referred to as ion-exchanged glass crystal, etc.

[0117] After ion exchange, a compressive stress layer (CS layer) of a certain depth is formed on the surface of the glass-ceramic, resulting in higher surface compressive stress and further improvement in its mechanical properties, such as surface hardness and fracture toughness, thus greatly enhancing its resistance to external forces. Compared with the original glass-ceramic, this strengthened glass-ceramic contains an additional hexagonal potassium nepheline crystal phase, which is located in the CS layer.

[0118] Specifically, the reinforced glass-ceramic includes the aforementioned glass-ceramic and a compressive stress layer located on the surface of the aforementioned glass-ceramic, the compressive stress layer containing a hexagonal potassium nepheline crystal phase. The compressive stress layer extends from the surface of the glass-ceramic to a certain depth. In addition to the crystal phases inherent in the glass-ceramic itself (the aforementioned sodium nepheline, forsterite, and TiO2 crystal phases), the compressive stress layer also contains a hexagonal potassium nepheline crystal phase. In other words, the reinforced glass-ceramic includes a glass body and compressive stress layers disposed on both sides of the glass body. The crystal composition and components of the glass body are identical to those of the aforementioned glass-ceramic. The crystal phases in the glass body include a sodium nepheline, forsterite, and TiO2 crystal phases. The crystal phases in the compressive stress layer include a sodium nepheline, forsterite, TiO2, and hexagonal potassium nepheline crystal phase. Alternatively, the reinforced glass-ceramic can be described as comprising a glass phase and a crystalline phase. The crystalline phase includes a sodium nepheline phase, a magnesium olivine phase, and a TiO2 phase. The surface of the reinforced glass-ceramic has a compressive stress layer that extends from both sides of the reinforced glass-ceramic to a certain depth inside. This compressive stress layer also contains a hexagonal potassium nepheline phase.

[0119] In this embodiment, the crystal size of at least one of the sodium nepheline phase, forsterite phase, TiO2 phase, and hexagonal potassium nepheline phase is less than or equal to 80 nm. A grain size ≤80 nm is far below the visible light wavelength range, allowing the strengthened glass-ceramic to have high visible light transmittance. In some embodiments, the crystal size of at least one of the above-mentioned crystal phases is ≤70 nm, ≤60 nm, ≤50 nm, ≤40 nm, ≤30 nm, ≤20 nm, or ≤10 nm. In some embodiments, approximately 60% or more of the crystal phases in the strengthened glass-ceramic have crystal sizes in the aforementioned nanometer range.

[0120] After ion exchange, the light transmittance of the strengthened microcrystalline glass remained almost unchanged. That is, the visible light transmittance of the strengthened microcrystalline glass with a thickness ≤1mm was greater than or equal to 85%.

[0121] In this embodiment, the depth of the compressive stress layer of the reinforced microcrystalline glass is greater than or equal to 50 μm. In some embodiments, the depth of the compressive stress layer may be greater than or equal to 60 μm, greater than or equal to 70 μm, greater than or equal to 80 μm, or greater than or equal to 90 μm. In other embodiments, the depth of the compressive stress layer may be greater than or equal to 100 μm, for example, it may be 110 μm-160 μm.

[0122] In this application, the hexagonal potassium nepheline crystal phase can be distributed in various ways within the compressive stress layer. For example, the hexagonal potassium nepheline crystal phase can be distributed only in the compressive stress layer on the side immediately adjacent to the surface of the strengthened glass-ceramic, or it can be distributed throughout the entire compressive stress layer. In other words, the distribution depth of the hexagonal potassium nepheline crystal phase can range from the surface of the strengthened glass-ceramic to a depth less than or equal to that of the stress layer.

[0123] Surface compressive stress is formed by the squeezing effect of ion exchange and the cell expansion effect after the sodium-containing nepheline phase and lepidolite are transformed into hexagonal potassium nepheline. Because larger ions can be crowded between the sodium-containing nepheline phase and / or lepidolite crystal phase, and because the phase transformation to hexagonal potassium nepheline is achieved, the reinforced glass-ceramic of this application can achieve higher strength. In the embodiments of this application, after ion exchange, the surface compressive stress of the reinforced glass-ceramic is greater than or equal to 800 MPa. In some embodiments, the surface compressive stress can be greater than or equal to 1000 MPa, greater than or equal to 1200 MPa, greater than or equal to 1400 MPa, or greater than or equal to 1600 MPa. In other embodiments, the surface compressive stress can be 1100 MPa-1300 MPa. The glass-ceramic of the embodiments of this application has a high ion exchange layer depth and a high surface compressive stress, thereby giving the glass high hardness and fracture toughness, ultimately resulting in excellent drop resistance in the end product.

[0124] Ion exchange of glass-ceramics can employ conventional ion exchange processes in the art, or other specific processes; this application does not limit this. In the embodiments of this application, the aforementioned ion exchange can be performed using a low-temperature ion exchange method. A one-step or two-step ion exchange process can be used to chemically strengthen the glass-ceramics.

[0125] In this embodiment, the one-step ion exchange process involves placing the microcrystalline glass in a salt bath for one-step ion exchange. The salt bath used in the one-step ion exchange process can be pure KNO3 molten salt, pure NaNO3 molten salt, or a mixed molten salt of KNO3 and NaNO3. In this case, a suitable ion exchange temperature can be 300-550℃, for example, 350-550℃ or 400-500℃. Specifically, when the salt bath is pure KNO3 molten salt or pure NaNO3 molten salt, the ion exchange process is carried out with KNO3 as the primary heat source. + →Na + Exchange is the primary process. When the salt bath is a mixed molten salt of KNO3 and NaNO3, it mainly involves Na. + →Li + Ion exchange and K + →Na + Ion exchange. The mass fraction of NaNO3 in this mixed molten salt can be 1%-30%.

[0126] In some embodiments of this application, for a two-step ion exchange process, the first salt bath used in the first step of ion exchange may comprise the following components by mass fraction: 30%-100% NaNO3 and 0-70% KNO3; the second salt bath used in the second step of ion exchange may comprise the following components by mass fraction: 0-20% NaNO3 and 80-100% KNO3. That is, the first salt bath may be pure NaNO3 molten salt, or a mixed molten salt of KNO3 and NaNO3; the second salt bath may be pure KNO3 molten salt, or a mixed molten salt of KNO3 and NaNO3.

[0127] In the above two-step ion exchange process, the first step of ion exchange uses Na... + →Li + The primary step is ion exchange, with the second step involving K+ ion exchange. + →Na + The primary ion exchange process is ion exchange. The temperatures of both the first and second ion exchange steps can be within the range of 300-550℃, and the combined time for both steps can be 2-24 hours. In some specific embodiments, the first ion exchange step can use a pure NaNO3 salt bath, with an ion exchange temperature of 460℃ and a time of 4 hours; the second step can use a mixed NaNO3 + KNO3 salt bath, with an ion exchange temperature of 460℃ and a time of 4 hours.

[0128] The compressive stress layer of the reinforced microcrystalline glass in this application can be formed by a two-step ion exchange process to obtain better mechanical properties. Specifically, high-pressure stress regions and low-pressure stress regions can be sequentially formed from the surface to the interior on both opposite surfaces of the reinforced microcrystalline glass. The deeper low-pressure stress region is formed by the first step of Na... + →Li + Ion exchange forms, while the high-pressure stress zone on the surface is formed by the first step of Na... + →Li + Ion exchange and the second step K + →Na + Formed through ion exchange.

[0129] This application also provides a reinforced microcrystalline glass, comprising the following components by molar percentage:

[0130] SiO2: 50%-66%,

[0131] Al2O3: 8%-15%,

[0132] Na2O: 8%-15%,

[0133] Li2O: 3%-6%,

[0134] K2O: 1%-3%,

[0135] MgO: 6%-14%,

[0136] CaO: 0-3%,

[0137] SrO: 0-3%,

[0138] BaO: 0-3%,

[0139] ZnO: 0-5%,

[0140] TiO2: 1%-5%;

[0141] The ratio of [Li2O+Na2O+K2O+MgO+CaO] / Al2O3 is 2.0-3.11;

[0142] The ratio of [Li₂O+Na₂O+K₂O] / [MgO+CaO] is 0.8-1.86;

[0143] The ratio of [(Li2O+Na2O+K2O)-Al2O3] / TiO2 is 0-6.0.

[0144] By rationally controlling the composition and proportions of each component, the reinforced glass-ceramic can simultaneously contain the aforementioned sodium-containing nepheline phase, forsterite phase, TiO2 phase, and hexagonal potassium nepheline phase. This reinforced glass-ceramic exhibits high visible light transmittance, high strength, a deep compressive stress layer, and high surface compressive stress, ultimately resulting in excellent drop resistance and impact resistance. Furthermore, this reinforced glass-ceramic can also be obtained by ion exchange of the aforementioned glass-ceramic.

[0145] In this embodiment, the reinforced microcrystalline glass has a compressive stress layer on its opposite two sides, which extends from the surface of the reinforced microcrystalline glass to a certain depth inside, and the hexagonal potassium nepheline crystal phase is located in the compressive stress layer.

[0146] Similar to the aforementioned reinforced microcrystalline glass, the reinforced microcrystalline glass here has a compressive stress layer depth greater than or equal to 50 μm; a surface compressive stress greater than or equal to 800 MPa and a thickness ≤ 1 mm; and a visible light transmittance greater than or equal to 85%. These details will not be repeated here.

[0147] It should be noted that the reinforced microcrystalline glass provided in this application embodiment is not only suitable for electronic information terminal products such as mobile phones, but also for transportation, construction and other fields. Specifically, it can be used for protective glass for vehicles, household appliances and buildings, such as protective glass for displays, dashboards and so on.

[0148] The embodiments of this application will be further described below through multiple examples.

[0149] Examples 1-16

[0150] Various raw materials were prepared according to the glass composition ratios listed in Tables 1.1-1.2 for each embodiment. After thorough and uniform mixing, a precursor glass composition was obtained. This composition was pre-fired at 700-800°C for 1-2 hours, then placed in a platinum crucible and melted at approximately 1500-1620°C for 6-10 hours to obtain a glass melt. Subsequently, the glass melt was cast into rectangular intermediate products and annealed at 570-750°C for 6-12 hours to obtain the precursor glass. The obtained rectangular precursor glass is transparent, colorless, and does not contain a crystalline phase.

[0151] Table 1.1 Glass composition of Examples 1-8

[0152]

[0153] Table 1.2 Glass composition of Examples 9-16

[0154]

[0155] Subsequently, the precursor glass of each embodiment was placed in a static furnace and subjected to heat treatment: the temperature was increased to the heat treatment temperature (within the range of 650-1000℃) at a rate of 1-5℃ / min, and held at that temperature for a certain time; then cooled to room temperature to obtain the corresponding microcrystalline glass. The appearance characteristics and crystal phase types of each microcrystalline glass obtained after heat treatment were recorded. The specific crystal phase types were obtained by X-ray diffraction (XRD) analysis.

[0156] The results showed that after heat treatment at 650℃ for 2 hours, the precursor glasses of Examples 1-8 were all colorless and transparent, and simultaneously contained the aforementioned sodium nepheline phase (Ne), TiO2-containing rutile phase (Ru), and forsterite phase (Fo). The sodium nepheline phase (Ne) included sodium nepheline and its silica solid solution, and sodium-potassium solid solution nepheline and its silica solid solution. Furthermore, the microcrystalline glasses of Examples 1 and 8 also contained lithium nepheline phase (LAS, LiAlSiO4), and the microcrystalline glasses of Examples 4-5 also contained TiO2-containing anatase phase (An). After heat treatment at 700℃ for 2 hours, the precursor glass of Example 9, and after heat treatment at 650℃ for 2 hours or 700℃ for 2 hours, the resulting microcrystalline glasses were all colorless and transparent, and simultaneously contained the aforementioned Ne, Ru, and Fo phases.

[0157] Figure 3 The images show the XRD patterns of the glass-ceramics obtained after different heat treatments of the precursor glass in Example 1 of this application. Figure 3It can be seen that after the precursor glass of Example 1 was treated with three different heat treatment regimes of 650℃ / 2h, 750℃ / 2h, and 850℃ / 2h, sodium-containing nepheline phase, TiO2-containing rutile phase, and forsterite crystal phase (Mg2SiO4) precipitated. Furthermore, the degree of crystallization of the sodium-containing nepheline phase and forsterite crystal phase increased with increasing heat treatment temperature. Figure 3 ZhongNa 6.8 Al 6.3 Si 9.7 O32 corresponds to the solid solution crystal phase of sodium nepheline and SiO2.

[0158] Figure 4 This is an electron microscope image of the glass-ceramic obtained in Example 1 of this application after heat treatment at 650°C for 2 hours. Figure 4 It can be seen that the crystal phase in this glass-ceramic is uniform in size and relatively small, about 60 nm.

[0159] Subsequently, the microcrystalline glass obtained from the above heat treatment was sliced ​​and surface-polished (thickness approximately 0.7 mm), and then chemically strengthened using a two-step method. The specific process is as follows: the first step involved ion exchange at 480°C for 6 hours using a mixed salt bath of NaNO3 (50 wt%) and KNO3 (50 wt%); the second step involved ion exchange at 450°C for 2 hours using a pure KNO3 salt bath. The surface compressive stress (CS) value and the depth of the CS layer (DOL) of the strengthened microcrystalline glass after ion exchange are shown in Table 2.

[0160] Table 2. CS values ​​and CS layer depths (DOL) of various reinforced glass-ceramics

[0161] CS(MPa) DOL(μm) Example 1 810 110 Example 2 880 105 Example 3 1000 98 Example 4 1100 85 Example 5 900 88 Example 6 880 94 Example 7 950 101 Example 8 990 109 Example 9 1100 88 Example 10 990 86 Example 11 970 92 Example 12 980 94 Example 13 880 91 Example 14 890 87 Example 15 900 88 Example 16 860 80

[0162] After ion exchange treatment, the microcrystalline glass with the composition of Examples 1-16 of this application also showed hexagonal potassium nepheline phase in the compressive stress layer of the resulting reinforced microcrystalline glass, with a grain size of about 25 nm. As shown in Table 2, the reinforced microcrystalline glass containing hexagonal potassium nepheline phase and the aforementioned sodium nepheline (Ne), TiO2, and forsterite (Fo) phases can achieve a surface compressive stress CS ≥ 800 MPa, and some can achieve CS ≥ 100 MPa; the depth DOL (i.e., the depth of the compressive stress layer) of the ion exchange layer is ≥ 80 μm, and some can achieve ≥ 100 μm, which is beneficial for improving drop resistance and can improve the reliability of end products.

[0163] Furthermore, the transmittance of each of the reinforced microcrystalline glasses provided in the embodiments of this application is greater than or equal to 85% in the visible light band of 380nm-750nm. It can be seen that the above-mentioned microcrystalline glasses are almost unaffected by light transmittance after ion exchange, which can meet the optical requirements of display and shooting of terminal products.

Claims

1. A microcrystalline glass characterized in that, The microcrystalline glass comprises a glass phase and a crystal phase, the crystal phase comprises a sodium-containing nepheline phase, a forsterite crystal phase and a TiO2 crystal phase, wherein the sodium-containing nepheline phase comprises one or more of sodium nepheline and its silica solid solution, sodium-potassium solid solution nepheline and its silica solid solution; the TiO2 crystal phase comprises at least one of an anatase phase and a rutile phase; the molar percentage of the following components in the microcrystalline glass satisfies: the ratio of [(Li2O+Na2O+K2O)-Al2O3] / TiO2 is 0.1-1.0, the ratio of [Li2O+Na2O+K2O] / [MgO+CaO] is 1.07-1.45, and MgO: 8%-13%.

2. The microcrystalline glass of claim 1, wherein, The crystal size of at least one of the sodium-containing nepheline phase, the forsterite crystal phase and the TiO2 crystal phase is less than or equal to 80 nm.

3. The microcrystalline glass of claim 1, wherein, The microcrystalline glass comprises the following components in terms of molar percentage: SiO2: 50%-66%, Al2O3: 8%-15%, Na2O: 8%-15%, Li2O: 3%-6%, K2O: 1%-3%, MgO: 8%-13%, CaO: 0-3%, SrO: 0-3%, BaO: 0-3%, ZnO: 0-5%, TiO2: 1%-5%; wherein the ratio of [Li2O+Na2O+K2O+MgO+CaO] / Al2O3 is 2.0-3.

11.

4. The microcrystalline glass of claim 3, wherein, The molar percentage of Li2O is 4%-5%.

5. The microcrystalline glass of claim 3, wherein, 25%≤Li2O / Na2O≤50%.

6. The microcrystalline glass of claim 3, wherein, The molar percentage of Al2O3 is 9%-13%.

7. The microcrystalline glass of claim 3, wherein, The ratio of [(Li2O+Na2O+K2O)-Al2O3] / TiO2 is 0.25-1.

0.

8. The microcrystalline glass of claim 3, wherein, The molar percentage of MgO is 8%-12%.

9. The microcrystalline glass of claim 3, wherein, The molar percentage of ZnO is 1%-4%.

10. The microcrystalline glass of claim 3, wherein, The sum of the molar percentages of CaO, SrO and BaO is less than or equal to 6%.

11. The microcrystalline glass of claim 3, wherein, The molar percentage of TiO2 is 2%-4%.

12. The glass-ceramic according to any one of claims 1 to 11, characterized in that, The visible light transmittance of the microcrystalline glass with a thickness of ≤1 mm is greater than or equal to 85%.

13. A strengthened microcrystalline glass characterized by, The strengthened microcrystalline glass comprises the microcrystalline glass as claimed in any one of claims 1-12 and a compressive stress layer located on the surface of the microcrystalline glass, the compressive stress layer contains a hexagonal kalsilite crystal phase.

14. The strengthened microcrystalline glass of claim 13, wherein, The crystal size of at least one of the sodium-containing nepheline phase, the forsterite crystal phase, the TiO2 crystal phase and the hexagonal kalsilite crystal phase is less than or equal to 80 nm.

15. The strengthened microcrystalline glass of claim 13, wherein, The depth of the compressive stress layer of the strengthened microcrystalline glass is greater than or equal to 50 μm.

16. The strengthened microcrystalline glass of any of claims 13-15, wherein, The surface compressive stress of the strengthened microcrystalline glass is greater than or equal to 800 MPa.

17. A strengthened microcrystalline glass characterized by, The strengthened microcrystalline glass comprises the following components in terms of molar percentage: SiO2: 50%-66%, Al2O3: 8%-15%, Na2O: 8%-15%, Li2O: 3%-6%, K2O: 1%-3%, MgO: 8%-13%, CaO: 0-3%, SrO: 0-3%, BaO: 0-3%, ZnO: 0-5%, TiO2: 1%-5%; The ratio of [Li2O+Na2O+K2O+MgO+CaO] / Al2O3 is 2.0-3.11; The ratio of [Li2O+Na2O+K2O] / [MgO+CaO] is 1.07-1.45; The ratio of [(Li2O+Na2O+K2O)-Al2O3] / TiO2 is 0.1-1.0; The crystal phase in the strengthened glass-ceramics includes a sodium-containing nepheline phase, a forsterite crystal phase, a TiO2 crystal phase and a hexagonal potash nepheline crystal phase, and the hexagonal potash nepheline crystal phase is only distributed in the surface layer of the strengthened glass-ceramics; the sodium-containing nepheline phase includes one or more of sodium nepheline and a silica solid solution thereof, a sodium-potassium solid solution nepheline and a silica solid solution thereof; the TiO2 crystal phase includes at least one of an anatase phase and a rutile phase.

18. The strengthened microcrystalline glass of claim 17, wherein, The strengthened glass-ceramics has a compressive stress layer on the opposite surfaces, and the depth of the compressive stress layer is greater than or equal to 50 μm; the hexagonal potash nepheline crystal phase is located in the compressive stress layer.

19. A terminal, characterized by The terminal further comprises a camera assembly located inside the shell, and the shell comprises a camera protection cover plate covering the camera assembly, wherein the camera protection cover plate is made of the strengthened glass-ceramics.

20. The terminal of claim 19, wherein, The shell comprises a display screen cover plate assembled on the front side of the terminal, and the display screen cover plate is made of the strengthened glass-ceramics.

21. The terminal of claim 19, wherein, The shell comprises a rear cover assembled on the rear side of the terminal, and the rear cover is made of the strengthened glass-ceramics.

22. The terminal of claim 19, wherein, The terminal further comprises a camera assembly located inside the shell, and the shell comprises a camera protection cover plate covering the camera assembly, wherein the camera protection cover plate is made of the strengthened glass-ceramics.

23. A terminal according to any of claims 19-22, characterised in that The thickness of the strengthened glass-ceramics is 0.4-2 mm.

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