Low-expansion microcrystalline glass and preparation method thereof

Abstract

The invention discloses low-expansion microcrystalline glass and a preparation method thereof, and belongs to the technical field of microcrystalline glass. The method comprises the steps of batch preparation, fusion molding, annealing and crystallization treatment. The invention relates to two different crystallization processes, the optimal nucleation and crystallization temperature is determined by utilizing a DSC test, and the optimal crystallization process is determined according to an XRD test result and an expansion performance test result. According to the method, the microcrystalline glass which is excellent in expansion performance and takes the beta-quartz solid solution as the main crystalline phase is generated through material formula and crystallization process control, the method has the advantages of being more accurate and more visual, and theoretical basis and reference value are provided for research and production of the microcrystalline glass.

Description

Technical Field

[0001] The invention belongs to the technical field of microcrystalline glass and relates to a low-expansion microcrystalline glass and a preparation method thereof. Background Art

[0002] With the increasing use of microcrystalline glass as a high-performance material in the field of high-end technology, especially in key applications in cutting-edge technology products such as smartphone covers and laser gyroscopes, more stringent requirements have been placed on the performance standards of microcrystalline glass. These applications not only require the material to have high strength, high hardness and excellent wear resistance, but also require it to exhibit stable physical and chemical properties under specific environmental conditions. Therefore, how to accurately control the crystallization process of microcrystalline glass in order to optimize its microstructure and macroscopic performance has become the key to improving the comprehensive performance of microcrystalline glass.

[0003] The crystallization process of glass-ceramics is a complex and delicate process. By adjusting parameters such as heat treatment temperature, holding time, and heating rate, the crystallinity of the crystalline phase and the size of the grains can be effectively controlled. The subtle regulation of this process is directly related to the change in the overall expansion coefficient of the glass, which in turn affects the thermal stability, dimensional stability, and mechanical properties of the material. More importantly, the directional induction of crystallization in the precursor glass to generate a β-quartz solid solution crystalline phase with negative expansion characteristics can make the glass-ceramics exhibit unique negative expansion properties, that is, when the temperature increases, the volume of the material decreases instead. This property is particularly important in the manufacture of precision instruments.

[0004] For example, in optical telescopes, the application of negative expansion glass-ceramics can effectively offset the deformation of lenses caused by temperature changes and ensure observation accuracy; in high-precision navigation equipment such as laser gyroscopes, its stable dimensional change characteristics help maintain the long-term stability and accuracy of the system. Therefore, negative expansion glass-ceramics are widely used in many high-tech fields such as optics, electronics, medical treatment, aerospace, etc., and have become one of the key materials to promote the development of related industries.

[0005] However, the uneven distribution of glass-ceramics grain size, the need to improve glass transmittance, and insufficient expansion coefficient control accuracy are still the main bottlenecks restricting its further widespread application. These physical property deficiencies make it difficult to meet the high standards of material performance required by high-end precision devices, especially in situations where there are extremely high requirements for dimensional accuracy, optical properties, and thermal stability. Therefore, in-depth research on the crystallization mechanism of glass-ceramics and the development of more sophisticated crystallization control technology to achieve precise control of properties such as grain size, transmittance, and expansion coefficient have become important issues that need to be solved urgently. Summary of the invention

[0006] The purpose of the present invention is to provide a low-expansion microcrystalline glass and a preparation method thereof, so as to solve the technical problem that the microcrystalline glass prepared by the prior art has poor physical properties such as grain size, light transmittance and expansion coefficient, and is difficult to meet the requirements of high-end precision devices.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a low-expansion glass-ceramics, whose components, by mass percentage, include 55% to 60% SiO2, 26% to 28% Al2O3, 3% to 5% Li2O, 0% to 1% Na2O, 0% to 1% K2O, 1% to 2% MgO, 5% to 6% P2O5, 1% to 3% ZrO2, 1% to 3% TiO2 and 0% to 0.3% clarifier.

[0009] Furthermore, the main crystalline phase of the low-expansion glass-ceramics is β-quartz solid solution; the crystallinity of the main crystalline phase is 80% to 90%, and the grain size is less than 100 nm.

[0010] Furthermore, the clarifier is SnO.

[0011] Furthermore, the total mass of the Na2O and the K2O accounts for 0% to 1% of the entire component.

[0012] Furthermore, the total mass of the ZrO2 and the TiO2 accounts for 4% to 6% of the entire component.

[0013] In a second aspect, the present invention provides a method for preparing the low expansion glass-ceramics, comprising the following steps:

[0014] The raw materials for preparing low-expansion glass-ceramics are mixed and placed in a furnace to be melted at high temperature to form glass liquid, which is then formed by a casting method;

[0015] Annealing the formed glass;

[0016] The annealed glass is crystallized to prepare low expansion glass-ceramics.

[0017] Furthermore, the conditions for high-temperature melting are: melting temperature is 1550°C to 1650°C, and melting time is 12h to 24h.

[0018] Furthermore, the annealing treatment conditions are: annealing temperature 600° C. to 650° C., annealing time 8 h to 10 h.

[0019] Furthermore, the crystallization treatment is carried out by two-step crystallization or one-step crystallization;

[0020] The specific steps of the one-step crystallization are: heating at a heating rate of 0.1°C / min to 5°C / min within a temperature range of 700°C to 870°C, and then keeping the temperature at 870°C for 5h to 24h.

[0021] Furthermore, the specific steps of the two-step crystallization are:

[0022] In the nucleation stage, the temperature is 680°C to 730°C for 4h to 48h;

[0023] In the crystallization stage, crystallization is carried out at a temperature of 830°C to 890°C for 1h to 3h.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention discloses a low-expansion glass-ceramic and a preparation method thereof. The low-expansion glass-ceramic is finally prepared by batch material preparation, melt molding, fine annealing and crystallization treatment in sequence. The crystallization process is optimized from the perspectives of crystallization method (one-step method or two-step method), nucleation and crystallization temperature determination method, and adjustment of heating rate. The grain growth is strictly controlled, and a controlled crystallization system for low-expansion glass-ceramic is proposed to keep the expansion coefficient of the glass-ceramic within a suitable range. The low-expansion glass-ceramic can be applied to the fields of optics, electronics, medical treatment, aviation, etc. The average thermal expansion coefficient of the prepared low-expansion glass-ceramic between -50°C and 200°C is ±3×10 -7 / ℃, visible light transmittance>90%, haze<0.1%, can be used in the field of smart display. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0027] Figure 1 is the DSC curve of the basic glass of the embodiment of the present invention;

[0028] Figure 2 This is the XRD curve of the glass-ceramics of Example 11 of the present invention. DETAILED DESCRIPTION

[0029] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used in the text are the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definition in this specification shall prevail.

[0030] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0031] Herein, all features such as values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to have included and specifically disclosed all possible secondary ranges and individual values ​​within the range (including integers and fractions).

[0032] In this document, unless otherwise specified, “includes,” “including,” “contains,” “has,” or similar terms cover the meanings of “consisting of” and “mainly consisting of,” for example, “A includes a” covers the meanings of “A includes a and other” and “A only includes a.”

[0033] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0034] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0035] The embodiment of the present invention discloses a low expansion glass-ceramic, whose main crystal phase is a β-quartz solid solution. The basic components of the glass-ceramic include SiO2, Al2O3, Li2O, Na2O, K2O, and MgO, and P2O5, ZrO2, and TiO2 are added as nucleating agents, and SnO is added as a clarifier. Specifically, by mass percentage, its components include 55% to 60% SiO2, 26% to 28% Al2O3, 3% to 5% Li2O, 0% to 1% Na2O, 0% to 1% K2O, 1% to 2% MgO, 5% to 6% P2O5, 1% to 3% ZrO2, 1% to 3% TiO2, and 0% to 0.3% SnO, and Na2O+K2O: 0% to 1%. , ZrO2+TiO2: 4% to 6%. The crystallinity of the main crystalline phase is 80% to 90%, and the grain size is less than 100 nm.

[0036] The embodiment of the present invention also discloses a method for preparing low-expansion glass-ceramics, comprising the following steps:

[0037] Step 1, mixing the raw materials for preparing low-expansion glass-ceramics and placing them in a furnace, melting them at high temperature to form glass liquid, and then forming them by casting;

[0038] In this step, the high temperature melting conditions are: melting temperature is 1550°C to 1650°C, and melting time is 12h to 24h.

[0039] Step 2, annealing the formed glass;

[0040] In this step, the annealing conditions are: annealing temperature 600° C. to 650° C., annealing time 8 h to 10 h.

[0041] Step 3, crystallizing the annealed glass to prepare low-expansion glass-ceramics.

[0042] In this step, the crystallization treatment is carried out in a two-step crystallization or a one-step crystallization;

[0043] The specific steps of the one-step crystallization are: heating at a heating rate of 0.1°C / min to 5°C / min within a temperature range of 700°C to 870°C, and then keeping the temperature at 870°C for 5h to 24h.

[0044] The specific steps of the two-step crystallization are:

[0045] In the nucleation stage, the nucleation temperature is 680℃~730℃ for 4h~48h. The method for determining the nucleation temperature is shown in Figure 1 : The precursor glass is subjected to DSC analysis to obtain a heat flow curve and a glass transition temperature Tg, which ranges from the transition point temperature Tg to Tg+50°C.

[0046] In the crystallization stage, the crystallization is carried out at a temperature of 830°C to 890°C for 1h to 3h. The crystallization temperature is determined by performing a thermal analysis on the precursor glass to obtain a heat flow curve, and the crystallization peak on the heat flow curve is taken as the object to determine the crystallization temperature, such as Figure 2 shown.

[0047] The role of the raw materials in the present invention is: SiO2 forms a network skeleton in the glass and exists as a network former; Al2O3 also exists as a network former. The content of Al2O3 in the present invention is relatively high. When SiO2 in β-quartz 4+ Al 3+ +Li +) are substituted regularly to form the target phase β-quartz solid solution of the present invention; Na2O and K2O have the effect of reducing the high temperature viscosity of the glass and improving the chemical stability of the glass, but excessive addition will lead to a larger thermal expansion coefficient of the glass, so the content of Na2O+K2O is 0% to 1%; MgO can improve the mechanical strength and chemical stability of the glass; P2O5, ZrO2 and TiO2 exist in the glass as crystal nucleating agents.

[0048] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0049] The following examples use conventional instruments and equipment in the art. The experimental methods in the following examples where specific conditions are not specified are usually carried out under conventional conditions or under conditions recommended by the manufacturer. The various raw materials used in the following examples are conventional commercial products unless otherwise specified, and their specifications are conventional specifications in the art. In the specification of the present invention and the following examples, unless otherwise specified, "%" means weight percentage, "part" means weight part, and ratio means weight ratio.

[0050] Embodiment 1:

[0051] Step 1, mixing the raw materials for preparing low-expansion microcrystalline glass and placing them in a furnace, melting them at a high temperature of 1600°C for 800 minutes to form glass liquid, and then forming them by casting; the raw materials for preparing the low-expansion microcrystalline glass, in terms of mass percentage, include: 58.63% SiO2, 26% Al2O3, 4% Li2O, 0.2% Na2O, 0.4% K2O, 1.1% MgO, 5.5% P2O5, 1% ZrO2, 3% TiO2 and 0.17% SnO.

[0052] Step 2: annealing the formed glass at a temperature of 610° C. for 530 minutes.

[0053] Step 3, nucleating the annealed glass at 700°C for 1440 minutes, and then crystallizing it at 850°C for 120 minutes to prepare low expansion glass-ceramics.

[0054] Embodiment 2:

[0055] Step 1, mixing the raw materials for preparing low-expansion microcrystalline glass and placing them in a furnace, melting them at a high temperature of 1620°C for 750 minutes to form glass liquid, and then forming them by casting; the raw materials for preparing the low-expansion microcrystalline glass, in terms of mass percentage, include: 56.62% SiO2, 27% Al2O3, 3% Li2O, 0.8% Na2O, 0.1% K2O, 1.5% MgO, 5.7% P2O5, 2.2% ZrO2, 2.8% TiO2 and 0.28% SnO.

[0056] Step 2: annealing the formed glass at a temperature of 640° C. for 550 minutes.

[0057] Step 3, nucleating the annealed glass at 720°C for 1440 minutes, and then crystallizing it at 850°C for 120 minutes to prepare low expansion glass-ceramics.

[0058] Embodiment 3:

[0059] Step 1, mixing the raw materials for preparing low-expansion microcrystalline glass and placing them in a furnace, melting them at a high temperature of 1640°C for 900 minutes to form molten glass, and then forming them by casting; the raw materials for preparing the low-expansion microcrystalline glass, in terms of mass percentage, include: 54.11% SiO2, 28% Al2O3, 5% Li2O, 0.1% Na2O, 0.7% K2O, 1.7% MgO, 5.1% P2O5, 3% ZrO2, 2.2% TiO2 and 0.09% SnO.

[0060] Step 2: annealing the formed glass at a temperature of 650° C. for 520 minutes.

[0061] Step 3, nucleating the annealed glass at 710° C. for 480 min, and then crystallizing it at 850° C. for 120 min to prepare low expansion glass-ceramics.

[0062] Embodiment 4:

[0063] Step 1, mixing the raw materials for preparing low-expansion microcrystalline glass and placing them in a furnace, melting them at a high temperature of 1600°C for 1100 minutes to form molten glass, and then forming them by casting; the raw materials for preparing the low-expansion microcrystalline glass, in terms of mass percentage, include: 57.08% SiO2, 26% Al2O3, 4% Li2O, 0.6% Na2O, 0.3% K2O, 1.8% MgO, 5.4% P2O5, 1.7% ZrO2, 2.9% TiO2 and 0.22% SnO.

[0064] Step 2: annealing the formed glass at a temperature of 630° C. for 580 minutes.

[0065] Step 3, nucleating the annealed glass at 710°C for 1440 minutes, and then crystallizing it at 850°C for 120 minutes to prepare low expansion glass-ceramics.

[0066] Embodiment 5:

[0067] Step 1, mixing the raw materials for preparing low-expansion glass-ceramics and placing them in a furnace, melting them at a high temperature of 1620°C for 750 minutes to form molten glass, and then forming them by casting; the raw materials for preparing the low-expansion glass-ceramics, in terms of mass percentage, include: 56.75% SiO2, 27% Al2O3, 5% Li2O, 0.4% Na2O, 0.2% K2O, 1.3% MgO, 5.6% P2O5, 2% ZrO2, 1.6% TiO2 and 0.15% SnO.

[0068] Step 2: annealing the formed glass at a temperature of 640° C. for 550 minutes.

[0069] Step 3, nucleating the annealed glass at 710°C for 2880 minutes, and then crystallizing it at 850°C for 120 minutes to prepare low expansion glass-ceramics.

[0070] Embodiment 6:

[0071] Step 1, mixing the raw materials for preparing low-expansion microcrystalline glass and placing them in a furnace, melting them at a high temperature of 1640°C for 900 minutes to form molten glass, and then forming them by casting; the raw materials for preparing the low-expansion microcrystalline glass, in terms of mass percentage, include: 54.11% SiO2, 28% Al2O3, 5% Li2O, 0.1% Na2O, 0.7% K2O, 1.7% MgO, 5.1% P2O5, 3% ZrO2, 2.2% TiO2 and 0.09% SnO.

[0072] Step 2: annealing the formed glass at a temperature of 650° C. for 520 minutes.

[0073] Step 3, nucleating the annealed glass at 710°C for 1440 minutes, and then crystallizing it at 830°C for 120 minutes to prepare low expansion glass-ceramics.

[0074] Embodiment 7:

[0075] Step 1, mixing the raw materials for preparing low-expansion microcrystalline glass and placing them in a furnace, melting them at a high temperature of 1600°C for 800 minutes to form glass liquid, and then forming them by casting; the raw materials for preparing the low-expansion microcrystalline glass, in terms of mass percentage, include: 58.63% SiO2, 26% Al2O3, 4% Li2O, 0.2% Na2O, 0.4% K2O, 1.1% MgO, 5.5% P2O5, 1% ZrO2, 3% TiO2 and 0.17% SnO.

[0076] Step 2: annealing the formed glass at a temperature of 610° C. for 530 minutes.

[0077] Step 3, nucleating the annealed glass at 710°C for 1440 minutes, and then crystallizing it at 870°C for 120 minutes to prepare low expansion glass-ceramics.

[0078] Embodiment 8:

[0079] Step 1, mixing the raw materials for preparing low-expansion microcrystalline glass and placing them in a furnace, melting them at a high temperature of 1600°C for 1100 minutes to form molten glass, and then forming them by casting; the raw materials for preparing the low-expansion microcrystalline glass, in terms of mass percentage, include: 57.08% SiO2, 26% Al2O3, 4% Li2O, 0.6% Na2O, 0.3% K2O, 1.8% MgO, 5.4% P2O5, 1.7% ZrO2, 2.9% TiO2 and 0.22% SnO.

[0080] Step 2: annealing the formed glass at a temperature of 630° C. for 580 minutes.

[0081] Step 3, nucleating the annealed glass at 710°C for 1440 minutes, and then crystallizing it at 850°C for 60 minutes to prepare low expansion glass-ceramics.

[0082] Embodiment 9:

[0083] Step 1, mixing the raw materials for preparing low-expansion microcrystalline glass and placing them in a furnace, melting them at a high temperature of 1600°C for 1100 minutes to form molten glass, and then forming them by casting; the raw materials for preparing the low-expansion microcrystalline glass, in terms of mass percentage, include: 57.08% SiO2, 26% Al2O3, 4% Li2O, 0.6% Na2O, 0.3% K2O, 1.8% MgO, 5.4% P2O5, 1.7% ZrO2, 2.9% TiO2 and 0.22% SnO.

[0084] Step 2: annealing the formed glass at a temperature of 630° C. for 580 minutes.

[0085] Step 3, nucleating the annealed glass at 710°C for 1440 minutes, and then crystallizing it at 850°C for 180 minutes to prepare low expansion glass-ceramics.

[0086] The crystallization treatment of Examples 1 to 9 adopts a two-step crystallization process, wherein the heating rate of the heating stage is 5° C. / min. The conditions of the two-step crystallization process and the performance parameters of the final product are shown in Table 1 below.

[0087] Table 1

[0088]

[0089] The crystal phases of Examples 1 to 9 are all β-quartz solid solutions. It can be seen from the above table that the nucleation temperatures of Examples 1 and 2 are lower or higher than the ideal nucleation temperature, and the nucleation time of Example 3 is relatively low, which results in insufficient precipitation of the nucleating agent from the glass phase, which is manifested as a larger grain size after crystallization and a lower overall crystallinity. The nucleation time of Example 5 is twice that of Example 4, but there is no obvious performance improvement. The crystallization temperatures of Examples 6 and 7 are too high or too low, resulting in smaller or larger grain sizes, which in turn affects the expansion coefficient. When the crystallization temperature is too high, the glass as a whole will experience a larger negative expansion phenomenon. The crystallization time of Examples 8 and 9 is too long or too short, which also results in smaller or larger grain sizes, which in turn affects the expansion coefficient. In comparison, the effect of the crystallization time on the final expansion coefficient is greater than the crystallization temperature.

[0090] Embodiment 10:

[0091] Step 1, mixing the raw materials for preparing low-expansion microcrystalline glass and placing them in a furnace, melting them at a high temperature of 1600°C for 1100 minutes to form molten glass, and then forming them by casting; the raw materials for preparing the low-expansion microcrystalline glass, in terms of mass percentage, include: 57.08% SiO2, 26% Al2O3, 4% Li2O, 0.6% Na2O, 0.3% K2O, 1.8% MgO, 5.4% P2O5, 1.7% ZrO2, 2.9% TiO2 and 0.22% SnO.

[0092] Step 2: annealing the formed glass at a temperature of 630° C. for 580 minutes.

[0093] Step 3, heating the annealed glass within a temperature range of 700°C to 870°C at a heating rate of 0.1°C / min, and then keeping the temperature at 870°C for 15 hours. , to prepare low expansion glass-ceramics.

[0094] Embodiment 11:

[0095] Step 1, mixing the raw materials for preparing low-expansion microcrystalline glass and placing them in a furnace, melting them at a high temperature of 1600°C for 800 minutes to form glass liquid, and then forming them by casting; the raw materials for preparing the low-expansion microcrystalline glass, in terms of mass percentage, include: 58.63% SiO2, 26% Al2O3, 4% Li2O, 0.2% Na2O, 0.4% K2O, 1.1% MgO, 5.5% P2O5, 1% ZrO2, 3% TiO2 and 0.17% SnO.

[0096] Step 2: annealing the formed glass at a temperature of 610° C. for 530 minutes.

[0097] Step 3, heating the annealed glass within a temperature range of 700°C to 870°C at a heating rate of 0.5°C / min, and then keeping the temperature at 870°C for 0.4h., to prepare low expansion glass-ceramics.

[0098] Embodiment 12:

[0099] Step 1, mixing the raw materials for preparing low-expansion microcrystalline glass and placing them in a furnace, melting them at a high temperature of 1620°C for 750 minutes to form glass liquid, and then forming them by casting; the raw materials for preparing the low-expansion microcrystalline glass, in terms of mass percentage, include: 56.62% SiO2, 27% Al2O3, 3% Li2O, 0.8% Na2O, 0.1% K2O, 1.5% MgO, 5.7% P2O5, 2.2% ZrO2, 2.8% TiO2 and 0.28% SnO.

[0100] Step 2: annealing the formed glass at a temperature of 640° C. for 550 minutes.

[0101] Step 3, heating the annealed glass within a temperature range of 700°C to 870°C at a heating rate of 1°C / min, and then keeping the temperature at 870°C for 15 hours. , to prepare low expansion glass-ceramics.

[0102] Embodiment 13:

[0103] Step 1, mixing the raw materials for preparing low-expansion microcrystalline glass and placing them in a furnace, melting them at a high temperature of 1640°C for 900 minutes to form molten glass, and then forming them by casting; the raw materials for preparing the low-expansion microcrystalline glass, in terms of mass percentage, include: 54.11% SiO2, 28% Al2O3, 5% Li2O, 0.1% Na2O, 0.7% K2O, 1.7% MgO, 5.1% P2O5, 3% ZrO2, 2.2% TiO2 and 0.09% SnO.

[0104] Step 2: annealing the formed glass at a temperature of 650° C. for 520 minutes.

[0105] Step 3, heating the annealed glass within a temperature range of 700°C to 870°C at a heating rate of 3°C / min, and then keeping the temperature at 870°C for 15 hours. , to prepare low expansion glass-ceramics.

[0106] Embodiment 14:

[0107] Step 1, mixing the raw materials for preparing low-expansion microcrystalline glass and placing them in a furnace, melting them at a high temperature of 1600°C for 1100 minutes to form molten glass, and then forming them by casting; the raw materials for preparing the low-expansion microcrystalline glass, in terms of mass percentage, include: 57.08% SiO2, 26% Al2O3, 4% Li2O, 0.6% Na2O, 0.3% K2O, 1.8% MgO, 5.4% P2O5, 1.7% ZrO2, 2.9% TiO2 and 0.22% SnO.

[0108] Step 2: annealing the formed glass at a temperature of 630° C. for 580 minutes.

[0109] Step 3, heating the annealed glass within a temperature range of 700°C to 870°C at a heating rate of 5°C / min, and then keeping the temperature at 870°C for 15 hours. , to prepare low expansion glass-ceramics.

[0110] Embodiment 15:

[0111] Step 1, mixing the raw materials for preparing low-expansion glass-ceramics and placing them in a furnace, melting them at a high temperature of 1620°C for 750 minutes to form molten glass, and then forming them by casting; the raw materials for preparing the low-expansion glass-ceramics, in terms of mass percentage, include: 56.75% SiO2, 27% Al2O3, 5% Li2O, 0.4% Na2O, 0.2% K2O, 1.3% MgO, 5.6% P2O5, 2% ZrO2, 1.6% TiO2 and 0.15% SnO.

[0112] Step 2: annealing the formed glass at a temperature of 640° C. for 550 minutes.

[0113] Step 3, heating the annealed glass within a temperature range of 700°C to 870°C at a heating rate of 0.5°C / min, and then keeping the temperature at 870°C for 5 hours., to prepare low expansion glass-ceramics.

[0114] Embodiment 16:

[0115] Step 1, mixing the raw materials for preparing low-expansion microcrystalline glass and placing them in a furnace, melting them at a high temperature of 1620°C for 750 minutes to form glass liquid, and then forming them by casting; the raw materials for preparing the low-expansion microcrystalline glass, in terms of mass percentage, include: 56.62% SiO2, 27% Al2O3, 3% Li2O, 0.8% Na2O, 0.1% K2O, 1.5% MgO, 5.7% P2O5, 2.2% ZrO2, 2.8% TiO2 and 0.28% SnO.

[0116] Step 2: annealing the formed glass at a temperature of 640° C. for 550 minutes.

[0117] Step 3, heating the annealed glass within a temperature range of 700°C to 870°C at a heating rate of 0.5°C / min, and then keeping the temperature at 870°C for 10 hours. , to prepare low expansion glass-ceramics.

[0118] Embodiment 17:

[0119] Step 1, mixing the raw materials for preparing low-expansion glass-ceramics and placing them in a furnace, melting them at a high temperature of 1620°C for 750 minutes to form molten glass, and then forming them by casting; the raw materials for preparing the low-expansion glass-ceramics, in terms of mass percentage, include: 56.75% SiO2, 27% Al2O3, 5% Li2O, 0.4% Na2O, 0.2% K2O, 1.3% MgO, 5.6% P2O5, 2% ZrO2, 1.6% TiO2 and 0.15% SnO.

[0120] Step 2: annealing the formed glass at a temperature of 640° C. for 550 minutes.

[0121] Step 3, heating the annealed glass within a temperature range of 700°C to 870°C at a heating rate of 0.5°C / min, and then keeping the temperature at 870°C for 20 hours. , to prepare low expansion glass-ceramics.

[0122] Embodiment 18:

[0123] Step 1, mixing the raw materials for preparing low-expansion microcrystalline glass and placing them in a furnace, melting them at a high temperature of 1640°C for 900 minutes to form molten glass, and then forming them by casting; the raw materials for preparing the low-expansion microcrystalline glass, in terms of mass percentage, include: 54.11% SiO2, 28% Al2O3, 5% Li2O, 0.1% Na2O, 0.7% K2O, 1.7% MgO, 5.1% P2O5, 3% ZrO2, 2.2% TiO2 and 0.09% SnO.

[0124] Step 2: annealing the formed glass at a temperature of 650° C. for 520 minutes.

[0125] Step 3, heating the annealed glass within a temperature range of 700°C to 870°C at a heating rate of 0.5°C / min, and then keeping the temperature at 870°C for 24 hours, to prepare low expansion glass-ceramics.

[0126] The crystallization treatment of Examples 10 to 18 adopts a one-step crystallization method, firstly heating to 700° C. at 5° C. / min, and then slowly heating. The conditions of the one-step crystallization method and the performance parameters of the final product are shown in Table 2 below.

[0127] Table 2

[0128]

[0129] The crystal phases of Examples 10 to 18 are all β-quartz solid solutions. As can be seen from the above table, according to Examples 10 and 11, the grains generated by the low heating rate are finer and denser, and the expansion performance is better than that of the two-step crystallization method. According to Examples 13 and 14, a faster heating rate will lead to insufficient nucleation, and the mutual extrusion effect of the grains during the growth process is small, which makes the grain size larger, and ultimately leads to a larger expansion coefficient, which fails to fully offset the positive expansion of the glass phase. According to Examples 15 and 16, a short crystallization holding time leads to insufficient grain growth, small grain size and low crystallinity. According to Examples 17 and 18, the crystallization holding time is too long, the grain size is large and the crystallinity is high, and the negative expansion of the crystal phase has completely offset the positive expansion of the glass phase and presents the characteristics of negative expansion.

[0130] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A low expansion glass-ceramic, characterized in that: In terms of mass percentage, its components include 55% to 60% SiO2, 26% to 28% Al2O3, 3% to 5% Li2O, 0% to 1% Na2O, 0% to 1% K2O, 1% to 2% MgO, 5% to 6% P2O5, 1% to 3% ZrO2, 1% to 3% TiO2 and 0% to 0.3% clarifier.

2. The low expansion glass-ceramic according to claim 1, characterized in that: The main crystal phase of the low expansion glass-ceramics is β-quartz solid solution; the crystallinity of the main crystal phase is 80% to 90%, and the grain size is less than 100nm.

3. The low expansion glass-ceramics according to claim 1, characterized in that: The clarifier is SnO.

4. The low expansion glass-ceramic according to claim 1, characterized in that: The total mass of the Na2O and the K2O accounts for 0% to 1% of the entire component.

5. The low expansion glass-ceramic according to claim 1, characterized in that: The total mass of the ZrO2 and the TiO2 accounts for 4% to 6% of the entire component.

6. A method for preparing low expansion glass-ceramics according to any one of claims 1 to 5, characterized in that: The following steps are involved: The raw materials for preparing low-expansion glass-ceramics are mixed and placed in a furnace to be melted at high temperature to form glass liquid, which is then formed by a casting method; Annealing the formed glass; The annealed glass is crystallized to prepare low expansion glass-ceramics.

7. The method for preparing low expansion glass-ceramics according to claim 6, characterized in that: The high-temperature melting conditions are: melting temperature of 1550° C. to 1650° C., and melting time of 12 h to 24 h.

8. The method for preparing low expansion glass-ceramics according to claim 6, characterized in that: The annealing treatment conditions are: annealing temperature 600° C. to 650° C., and annealing time 8 h to 10 h.

9. The method for preparing low expansion glass-ceramics according to claim 6, characterized in that: The crystallization treatment method is two-step crystallization or one-step crystallization; The specific steps of the one-step crystallization are: heating at a heating rate of 0.1°C / min to 5°C / min within a temperature range of 700°C to 870°C, and then keeping the temperature at 870°C for 5h to 24h.

10. The method for preparing low expansion glass-ceramics according to claim 9, characterized in that: The specific steps of the two-step crystallization are: In the nucleation stage, the temperature is 680°C to 730°C for 4h to 48h; In the crystallization stage, crystallization is carried out at a temperature of 830°C to 890°C for 1h to 3h.

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