A controllable transparency glass-ceramic containing calcium-rich submicron crystals and a preparation method thereof

Abstract

The present invention relates to a controllable transparency glass-ceramic containing calcium-rich sub-micron crystals and a preparation method thereof. The glass-ceramic includes a dicalcium silicate (Ca₂SiO₄) crystal phase (α-Ca₂SiO₄), a wollastonite (CaSiO₃) crystal phase, and a glass phase, wherein α-Ca₂SiO₄ is a sub-micron crystal phase and is dispersed in the glass phase. The present invention utilizes a casting molding process to obtain a calcium-rich sub-micron glass-ceramic containing α-Ca₂SiO₄ by reasonably configuring the basic glass composition and optimizing the heat treatment system. The present invention controls the crystal type and crystal growth size by varying the contents of ZrO₂ and P₂O₅, thereby adjusting the transparency of the glass-ceramic. The preparation method of the glass-ceramic of the present invention adopts a casting process, and by adjusting the temperature and holding time of the heat treatment process, effective control over the number of crystal nuclei and the grain size in the glass-ceramic can be achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of glass ceramics, and particularly relates to a controllable transparency glass ceramic containing calcium-rich submicron crystals and a preparation method thereof. Background Art

[0002] Industrial solid waste is rich in main components for preparing glass ceramics such as SiO2, CaO, MgO, and Al2O3. Therefore, preparing slag glass ceramics has become an important way to reduce and utilize industrial solid waste with high value. CaO in industrial solid waste is one of the oxides with the highest content after SiO2. For example, the CaO content in iron tailings > 22 wt.%, the CaO content in chromite slag > 30 wt.%, the CaO content in blast furnace slag > 35 wt.%, and the CaO content in steel slag can reach 35 - 60 wt.%. In existing research, the target crystal phases for preparing glass ceramics from industrial solid waste mainly include calcium-poor phase forsterite (Mg2SiO4), cordierite (Mg2Al4Si5O 18 ) and enstatite phase (Mg2Si2O6); calcium-containing phase pyroxene (Ca(Mg,Fe)(Si,Al)2O6), diopside (CaMgSi2O6), anorthite phase (CaAl2Si2O8), as well as calcium-rich phase wollastonite crystal phase (CaSiO3) and calcium aluminosilicate phase (Ca2Al2SiO7), etc. Among them, calcium-containing and calcium-rich crystal phases are the preferred crystal phases for efficiently utilizing calcium-rich industrial solid waste. However, the calcium-silicon ratio in calcium-containing pyroxene, diopside, and anorthite crystal phases is only 1:2, making it difficult to efficiently utilize CaO in calcium-rich industrial solid waste.

[0003] The calcium-silicon ratio in the wollastonite crystal phase is 1:1, but wollastonite mostly crystallizes on the surface. The crystals grow from the surface to the interior and mostly precipitate in the form of needles or rods. At present, the preparation methods are mostly sintering methods, with high energy consumption during the preparation process. The wollastonite glass ceramics prepared have many pores, poor transparency, and low mechanical properties such as hardness, thus limiting the application fields of the materials. For example, Patent CN 103771713 A discloses a process for preparing β-wollastonite glass-ceramics using calcium silicate tailings remaining from the process of preparing sodium aluminosilicate hydrate by alkali leaching and desilication of fly ash and coal gangue as raw materials and adopting a traditional sintering process. Based on this process, the raw materials need to go through multiple processes such as high-temperature melting, water quenching, crushing, ball milling, granulation, ball milling, forming, and subsequent nucleation and crystallization heat treatment to be made into the final product. During the heat treatment of the product, a large number of crystals grow rapidly from the surface of the raw material particles to the center of the particles. As a result, a large number of grain boundaries will be formed inside the final material product. At the same time, the rapid crystallization on the surface of the glass batch will hinder ion diffusion. Therefore, a large number of pores will inevitably exist inside the prepared product. Whether it is grain boundaries or pores, they will scatter incident light, ultimately resulting in the opacity of the product.

[0004] Although the calcium-silicon ratio of the calcium-rich phase gehlenite (Ca2Al2SiO7) can reach 2:1, it has high requirements for the Al content in the raw material composition. Therefore, in order to highly utilize calcium-rich solid waste in the industrial field, it is urgent to find a glass-ceramic with a calcium-silicon ratio crystal phase as the target crystal phase and a simple preparation process. Dicalcium silicate (Ca2SiO4) is a crystal with a calcium-silicon ratio of 2:1, and its composition expressed in oxides is 2CaO·SiO2. Ca2SiO4 contains five crystal forms: α-Ca2SiO4, α′ H -Ca2SiO4, α′ L -Ca2SiO4, β-Ca2SiO4, and γ-Ca2SiO4. Currently, there are no papers or patent reports on the preparation of glass-ceramics with dicalcium silicate (Ca2SiO4) as the main crystal phase by the method of melt casting molding. Summary of the Invention

[0005] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a controllable transparency glass-ceramic containing calcium-rich submicron crystals and a preparation method thereof.

[0006] In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0007] A controllable transparency glass-ceramic containing calcium-rich submicron crystals, the glass-ceramic includes dicalcium silicate Ca2SiO4 crystal phase, wollastonite CaSiO3 crystal phase and glass phase, wherein the Ca2SiO4 crystal phase is a submicron crystal phase and is diffusely distributed in the glass phase.

[0008] The Ca2SiO4 crystal phase is the α-Ca2SiO4 crystal phase.

[0009] The basic formula of the glass-ceramic includes the following components in weight percentage: SiO2 46-60%, Al2O3 5-10%, CaO 10-25%, BaCO3 0-10%, BaSO4 0-10%, ZnO 2-5%, KCl 3-6%, Na2O+K2O 10-18%, CaF2+Cr2O3+CuO≤8%, ZrO2 0-8%, P2O5 0-8%.

[0010] The basic formula of the glass-ceramic includes the following components in weight percentage: SiO2 46-60%, Al2O3 5-10%, CaO 10-25%, BaCO3 0-10%, BaSO4 0-10%, ZnO 2-5%, KCl 3-6%, Na2O+K2O 10-18%, CaF2+Cr2O3+CuO≤8%, ZrO2 0-3%, P2O5 1-5%.

[0011] The basic formula of the glass-ceramic includes the following components in weight percentages: SiO2 46-60%, Al2O3 5-10%, CaO 10-25%, BaCO3 0-10%, BaSO4 0-10%, ZnO 2-5%, KCl 3-6%, Na2O+K2O 10-18%, CaF2+Cr2O3+CuO ≤8%, ZrO2 3-8%, P2O5 0-1%.

[0012] The grain size of the Ca2SiO4 crystal phase is 100 nm to 600 nm.

[0013] The preparation method of the glass-ceramic includes the following steps:

[0014] (1) Preparation of the mixture: Weigh each component according to the basic formula of the glass-ceramic and mix them evenly;

[0015] (2) High-temperature melting and shaping of the mixture: Heat the mixture at a heating rate of 3 °C / min to 1445 °C - 1650 °C, and keep it at this temperature for 1 - 3 h to obtain the glass melt;

[0016] (3) Preparation of the annealed glass: After the glass melt is completely melted, clarified and homogenized, pour the glass melt into a preheated mold for casting. Then, put the shaped glass into a muffle furnace and anneal it at 600 °C for 2 h. After annealing, let the annealed glass cool in the muffle furnace to room temperature;

[0017] (4) Preparation of the glass-ceramic: Obtain it after subjecting the annealed glass to two-step heat treatment of nucleation and crystallization.

[0018] The specific method of the heat treatment is as follows: Heat from room temperature to 700 °C - 850 °C at a heating rate of 3 °C / min for nucleation, and keep it at this temperature for 1 - 3 h; after insulation, continue to heat to 900 °C - 1000 °C at a heating rate of 3 °C / min for crystallization, and keep it at this temperature for 1 - 3 h; after the insulation ends, let the glass-ceramic cool in the furnace to room temperature, then it is obtained.

[0019] Advantages of the present invention

[0020] The present invention relates to a controllable transparency glass-ceramic containing calcium-rich submicron crystals. The glass-ceramic includes a dicalcium silicate (Ca2SiO4) crystal phase (α-Ca2SiO4), a wollastonite (CaSiO3) crystal phase and a glass phase, wherein α-Ca2SiO4 is a submicron crystal phase and is diffusely distributed in the glass phase. The present invention uses a casting and molding process, and obtains a calcium-rich submicron glass-ceramic containing α-Ca2SiO4 by reasonably configuring the basic glass composition and optimizing the heat treatment system.

[0021] The present invention controls the crystal type and crystal growth size by varying the contents of ZrO2 and P2O5, thereby regulating the transparency of the glass-ceramics. When the P2O5 content is 1–5 wt%, and the ZrO2 content is 0–3 wt%, the glass-ceramics are milky white. When the ZrO2 content increases from 3 wt% to 8 wt%, and the P2O5 content decreases from 1 wt% to 0 wt%, the transparency of the glass-ceramics increases significantly. By doping a small amount of Cr2O3 and CuO, emerald green glass-ceramics can be prepared.

[0022] Due to the strong overall crystallization ability of this submicron Ca2SiO4 and its uniform distribution in the glass phase, the hardness of the glass-ceramics is superior to that of the existing calcium-rich phase glass-ceramics. Moreover, due to the change in the addition amounts of ZrO2 and P2O5, the transmittance of visible light and near-infrared light of the glass-ceramics can be adjusted. Therefore, it can be used as a filter in optical components, thereby broadening the application fields of calcium-rich glass-ceramics.

[0023] The glass-ceramics preparation method of the present invention adopts a casting process. By adjusting the temperature and holding time of the heat treatment process, the number of crystal nuclei and the grain size in the glass-ceramics can be effectively controlled. When the nucleation temperature is 730 °C and the crystallization holding time is 1 hour, the sample grains are about 200 nm; when the nucleation temperature is increased (for example, 850 °C) and the crystallization holding time is increased to 2 hours, the sample grain size can increase to 300 nm - 600 nm, and at the same time, the content of Ca2SiO4 crystals increases significantly.

[0024] The raw materials used to prepare the glass-ceramics of the present invention are ordinary chemical reagents, and waste materials such as calcium-rich silicate minerals can also be used. Using solid waste can not only achieve the full utilization of calcium-rich silicate mineral solid waste, turning waste into treasure, but also provide a new way for the resource utilization of high-calcium minerals in nature and high-calcium solid waste in the industrial field. It can also provide a basic material for the development of Ca2SiO4-based fluorescent materials, and provide new ideas for improving the overall crystallization and material hardness of calcium-rich glass-ceramics. Description of the Drawings

[0025] Figure 1 Macrophotographs of Examples 1, 2, and 3 of the calcium-rich submicron crystal controllable transparency glass-ceramics of the present invention.

[0026] Figure 2 XRD photographs of Examples 1, 2, and 3 of the calcium-rich submicron crystal controllable transparency glass-ceramics of the present invention.

[0027] Figure 3 SEM photographs of Examples 1, 2, and 3 of the calcium-rich submicron crystal controllable transparency glass-ceramics of the present invention.

[0028] Figure 4Transmittance spectra in the visible and near-infrared regions of the glass ceramics of Example 1, Example 2, and Example 3 of the calcium-rich submicron crystalline glass ceramics of the present invention. Detailed implementation manners

[0029] The following further elaborates on the detailed implementation manners of the present invention in conjunction with examples.

[0030] Example 1

[0031] A controllable transparency glass ceramic containing calcium-rich submicron crystals is prepared by a casting process. The specific steps are as follows:

[0032] (1) Preparation of the mixture: Weigh SiO2, CaO, Al2O3, BaCO3, ZnO, Na2O+K2O, KCl, CaF2, ZrO2, and P2O5 according to the mass percentages shown in Table 1, mix them evenly, and put them into a corundum crucible.

[0033] Table 1 Mass percentages (wt.%) of each raw material in Example 1

[0034] <![CDATA[SiO2]]> CaO <![CDATA[Al2O3]]> <![CDATA[BaCO3]]> ZnO <![CDATA[Na2O+K2O]]> KCl <![CDATA[CaF2]]> <![CDATA[ZrO2]]> <![CDATA[P2O5]]> Total 48.1 12.9 6.9 6.5 2.6 12.9 4.1 1.7 1.7 2.6 100

[0035] (2) High-temperature melting and shaping of the mixture: Place the mixture together with the corundum crucible in a high-temperature silicon molybdenum rod furnace, heat the mixture at a heating rate of 3 °C per minute to 1450 °C, and hold for 2 hours;

[0036] (3) Preparation of the annealed glass: After the glass liquid in step (2) is completely melted, clarified, and homogenized, take out the corundum crucible containing the glass liquid, pour the glass liquid into a preheated mold for casting, and then put the formed glass into a muffle furnace for annealing at 600 °C for 2 hours. Turn off the power of the muffle furnace and let the annealed glass cool in the muffle furnace to room temperature;

[0037] (4) Preparation of the glass ceramic: After subjecting the annealed glass obtained in step (3) to two-step heat treatment of nucleation and crystallization, a glass ceramic containing calcium-rich submicron crystals is obtained. The heat treatment regime is as follows:

[0038] Heat from room temperature to 850 °C for nucleation at a heating rate of 3 °C / min, and hold at this temperature for 2 hours; after holding, continue to heat to 1000 °C for crystallization at a heating rate of 3 °C / min, and hold at this temperature for 1 hour; then turn off the power of the muffle furnace and let the glass ceramic cool in the furnace to room temperature, thus obtaining the controllable transparency glass ceramic containing calcium-rich submicron crystals of the present invention.

[0039] The macroscopic photograph of the obtained controllable transparency glass ceramic with calcium-rich submicron crystals is as Figure 1 shown. From Figure 1It can be seen that the glass-ceramic is milky white and opaque.

[0040] The XRD photograph of the glass-ceramic with controllable transparency containing calcium-rich submicron crystals is as Figure 2 shown. From Figure 2 it can be seen that the glass-ceramic contains α-Ca2SiO4 crystal phase (calcium-rich phase) and wollastonite CaSiO3 crystal phase (calcium-containing phase).

[0041] The SEM photograph of the glass-ceramic with controllable transparency containing calcium-rich submicron crystals is as Figure 3 shown. From Figure 3 it can be seen that the dendritic crystals arranged in parallel in the figure of Example 1 are wollastonite CaSiO3 crystal phase, and the short rod-shaped submicron crystals attached to the wollastonite CaSiO3 crystal phase are α-Ca2SiO4 crystal phase. The α-Ca2SiO4 crystal phase is a submicron crystal phase with a grain size of 100 nm to 600 nm (such as 100 nm, 200 nm, 500 nm, etc.) and is uniformly distributed in the glass phase.

[0042] The transmittance of the glass-ceramic with controllable transparency containing calcium-rich submicron crystals is as Figure 4 shown. From Figure 4 it can be seen that the glass-ceramic containing calcium-rich submicron crystals has a shielding effect on visible light, but has a good transmittance to near-infrared light. When the wavelength is 2400 nm, the transmittance can reach 81%.

[0043] Example 2

[0044] A glass-ceramic with controllable transparency containing calcium-rich submicron crystals is prepared by a casting process method, and the specific steps are as follows:

[0045] (1) Preparation of the mixture: Weigh SiO2, CaO, Al2O3, BaSO4, ZnO, Na2O + K2O, KCl, CaF2, ZrO2 and P2O5 according to the mass percentages shown in Table 1, mix them evenly and put them into a corundum crucible.

[0046] Table 2 Mass percentages (wt.%) of each raw material in Example 2

[0047] <![CDATA[SiO2]]> CaO <![CDATA[Al2O3]]> <![CDATA[BaSO4]]> ZnO <![CDATA[Na2O+K2O]]> KCl <![CDATA[CaF2]]> <![CDATA[ZrO2]]> <![CDATA[P2O5]]> Total 48.1 12.9 6.9 6.5 2.6 12.9 4.1 1.7 3.4 0.9 100

[0048] (2) High-temperature melting and forming of the mixture: Place the mixture together with the corundum crucible in a high-temperature silicon molybdenum rod furnace and heat the mixture at a heating rate of 3 °C per minute to 1450 °C, and keep it warm for 2 hours;

[0049] (3) Preparation of annealed glass: After the glass melt in step (2) is completely melted, clarified and homogenized, take out the corundum crucible containing the glass melt, and cast the glass melt into a preheated mold for casting. Subsequently, put the formed glass into a muffle furnace and anneal it at 600 °C for 2 hours. Turn off the power of the muffle furnace and let the annealed glass cool down to room temperature in the muffle furnace;

[0050] (4) Preparation of glass-ceramics: The annealed glass obtained in step (3) is subjected to two-step heat treatment of nucleation and crystallization to obtain a glass-ceramic containing calcium-rich submicron crystals. The heat treatment regime is as follows: Heat from room temperature to 850 °C at a heating rate of 3 °C / min for nucleation and hold at this temperature for 2 hours; continue to heat to 1000 °C at a heating rate of 3 °C / min for crystallization and hold at this temperature for 2 hours; then turn off the power of the muffle furnace and let the glass-ceramic cool to room temperature in the furnace, thus obtaining the controllable transparency glass-ceramic containing calcium-rich submicron crystals of the present invention.

[0051] The macroscopic photograph of the obtained controllable transparency glass-ceramic containing calcium-rich submicron crystals is as Figure 1 shown. From Figure 1 it can be seen that the glass-ceramic is a transparent sample.

[0052] The XRD photograph of the obtained controllable transparency glass-ceramic containing calcium-rich submicron crystals is as Figure 2 shown. From Figure 2 it can be seen that the glass-ceramic contains α-Ca2SiO4 crystal phase (calcium-rich phase) and wollastonite CaSiO3 crystal phase (calcium-containing phase).

[0053] The SEM photograph of the obtained controllable transparency glass-ceramic containing calcium-rich submicron crystals is as [[ID=2,1]] Figure 3 shown. From Figure 3 it can be seen that a large number of granular crystals are distributed in the glass-ceramic of Example 2. Combining with XRD analysis, it can be known that the crystal is α-Ca2SiO4, and the grain size is uniformly distributed between 100 - 300 nm in the glass phase.

[0054] The transmittance of the obtained controllable transparency glass-ceramic containing calcium-rich submicron crystals is as Figure 4 shown. From Figure 4 it can be seen that the glass-ceramic containing calcium-rich submicron crystals has good transmittance to visible light and near-infrared light. The transmittance to visible light can reach 70%, and the transmittance to near-infrared light with a wavelength of 2400 nm can reach 83%.

[0055] Example

[0056] A controllable transparency glass-ceramic containing calcium-rich submicron crystals is prepared by a casting process method, and the specific steps are as follows:

[0057] (1) Preparation of the mixture: Weigh SiO2, CaO, Al2O3, BaCO3, ZnO, Na2O+K2O, KCl, CaF2, ZrO2, P2O5, Cr2O3 and CuO according to the mass percentages shown in Table 1, mix them evenly and put them into a corundum crucible.

[0058] Table 3 Mass percentages of raw materials in Example 3 (wt.%)

[0059] <![CDATA[SiO2]]> CaO <![CDATA[Al2O3]]> <![CDATA[BaCO3]]> ZnO <![CDATA[Na2O+K2O]]> KCl <![CDATA[CaF2]]> <![CDATA[ZrO2]]> <![CDATA[P2O5]]> <![CDATA[Cr2O3]]> CuO Total 47.8 12.8 6.8 6.4 2.5 12.8 4.1 1.7 1.7 2.6 0.4 0.4 100

[0060] (2) High-temperature melting and shaping of the mixture: Place the mixture together with the corundum crucible in a high-temperature silicon molybdenum rod furnace and heat the mixture at a heating rate of 3°C per minute to 1450°C, and hold for 2 hours.

[0061] (3) Preparation of annealed glass: After the glass melt in step (2) is completely melted, clarified and homogenized, take out the corundum crucible containing the glass melt, and pour the glass melt into a preheated mold for casting. Then put the shaped glass into a muffle furnace and anneal at 600°C for 2 hours. Turn off the power of the muffle furnace and let the annealed glass cool in the muffle furnace to room temperature.

[0062] (4) Preparation of glass-ceramics: The annealed glass obtained in step (3) is subjected to two-step heat treatment of nucleation and crystallization to obtain glass-ceramics containing calcium-rich submicron crystals. The heat treatment regime is as follows: Heat from room temperature to 850°C at a heating rate of 3°C / min for nucleation and hold at this temperature for 2 hours; continue to heat to 1000°C at a heating rate of 3°C / min for crystallization and hold at this temperature for 1 hour; then turn off the power of the muffle furnace and let the glass-ceramics cool in the muffle furnace to room temperature, that is, the controllable transparency glass-ceramics containing calcium-rich submicron crystals of the present invention are obtained.

[0063] The macroscopic photograph of the controllable transparency glass-ceramics with calcium-rich submicron crystals is as Figure 1 shown. As can be seen from Figure 1 it, the glass-ceramics are emerald green samples.

[0064] The XRD photograph of the controllable transparency glass-ceramics with calcium-rich submicron crystals is as Figure 2 shown. As can be seen from Figure 2 it, the glass-ceramics contain α-Ca2SiO4 crystal phase (calcium-rich phase) and wollastonite CaSiO3 crystal phase (calcium-containing phase).

[0065] The SEM photograph of the controllable transparency glass-ceramics with calcium-rich submicron crystals is as Figure 3 shown. As can be seen from Figure 3It can be seen that in the figure of Example 3, the large dendritic branches in grayish-white parallel arrangement are wollastonite CaSiO3 crystal phases, and the wollastonite CaSiO3 grows directionally along the same direction. The short rod-shaped crystals are α-Ca2SiO4 crystal phases. The grain size of α-Ca2SiO4 is between 100 nm and 600 nm. The α-Ca2SiO4 crystals do not have an obvious directional growth orientation but are uniformly distributed in the glass-ceramic along different directions.

[0066] The transmittance of the calcium-rich submicron crystal-containing controllable transparency glass-ceramic obtained is as Figure 4 shown. It can be seen from Figure 4 that this calcium-rich submicron crystal-containing glass-ceramic has a shielding effect on visible light, but has a good transmittance to near-infrared light. When the wavelength is 2400 nm, the transmittance can reach 61%.

[0067] The physical and chemical properties of the glass-ceramic containing calcium-rich submicron crystals of the present invention are shown in the following table.

[0068] Table 4 Physical and Chemical Properties of Glass-Ceramics in Examples 1 - 3

[0069] Flexural strength (MPa) Microhardness (GPa) Maximum near-infrared transmittance (%) Maximum visible light transmittance (%) Test standard GB / T6569-2006 GB / T 16534-2009 GB / T 5433-85 GB / T 5433-85 Example 1 80.54 10.00 81 10 Example 2 104.92 13.66 83 70 Example 3 100.08 11.00 61 0

[0070] It can be obtained from the above table that the glass-ceramic of the present invention has excellent microhardness and good flexural strength, and can transmit near-infrared light while selectively absorbing visible light.

Claims

1. A controllable transparency glass-ceramic containing calcium-rich submicron crystals, characterized in that, The glass-ceramic includes a dicalcium silicate Ca2SiO4 crystal phase, a wollastonite CaSiO3 crystal phase, and a glass phase, wherein the Ca2SiO4 crystal phase is a sub-micron crystal phase and is dispersedly distributed in the glass phase; the Ca2SiO4 crystal phase is an α-Ca2SiO4 crystal phase; The basic formula of the glass-ceramic includes the following components in weight percentages: SiO2 46 - 60%, Al2O3 5 - 10%, CaO 10 - 25%, BaCO3 0 - 10%, BaSO4 0 - 10%, ZnO 2 - 5%, KCl 3 - 6%, Na2O + K2O 10 - 18%, CaF2 + Cr2O3 + CuO ≤8%, ZrO2 0 - 8%, P2O5 0 - 8%; When the P2O5 content is 1 - 5% and the ZrO2 content is 0 - 3%, the glass-ceramic is milky white; when the ZrO2 content increases from 3% to 8% and the P2O5 content decreases from 1% to 0%, the transparency of the glass-ceramic significantly increases.

2. The glass-ceramic according to claim 1, characterized in that, The grain size of the Ca2SiO4 crystal phase is 100 nm - 600 nm.

3. The preparation method of the glass-ceramics according to claim 1, characterized in that, It includes the following steps: (1) Preparation of the mixture: Weigh each component according to the basic formula of the glass-ceramic and mix them evenly; (2) High-temperature melting and shaping of the mixture: Heat the mixture at a heating rate of 3 °C / min to 1445 °C - 1650 °C, and keep it at this temperature for 1 - 3 h to obtain a glass melt; (3) Preparation of the annealed glass: After the glass melt is completely melted, clarified, and homogenized, pour the glass melt into a preheated mold for casting and shaping. Then, put the shaped glass into a muffle furnace and anneal it at 600 °C for 2 h. After annealing, cool the annealed glass in the muffle furnace to room temperature with the furnace; (4) Preparation of the glass-ceramic: Obtain it after the annealed glass undergoes two-step heat treatments of nucleation and crystallization.

4. The preparation method according to claim 3, characterized in that, The specific method of the heat treatment is as follows: Heat from room temperature to 700 °C - 850 °C at a heating rate of 3 °C / min for nucleation, and keep it at this temperature for 1 - 3 h; after insulation, continue to heat to 900 °C - 1000 °C at a heating rate of 3 °C / min for crystallization, and keep it at this temperature for 1 - 3 h; after the insulation ends, let the glass-ceramic cool to room temperature with the furnace.

Images