Glass ceramic composite material and preparation method thereof

Abstract

The invention provides a glass ceramic composite material and a preparation method thereof, and belongs to the technical field of dielectric insulating materials. The method comprises the following steps: mixing SiO2, a calcium compound and a sodium compound, and grinding to obtain a mixture; the mixture is heated to be molten, and a melt is obtained; pouring the melt into a mold and carrying out annealing treatment to obtain a glass piece; sequentially carrying out first heat treatment and second heat treatment on the glass piece to obtain a glass ceramic composite material; wherein in the mixture, the molar percentage content of the Si element is nSi, the molar percentage content of the Ca element is nCa, the molar percentage content of the Na element is nNa, and nSi, nCa and nNa meet the following conditions: nSi + nCa + 0.5 nNa = 100%, the content of nSi is 40-52%, and the content of nCa is 32-38%; the temperature of the first heat treatment is 600-650 DEG C, and the temperature of the second heat treatment is 650-700 DEG C. The invention aims to provide the glass ceramic composite material with low dielectric loss and high breakdown strength.

Description

Technical Field

[0001] This invention relates to the field of dielectric insulating materials technology, specifically to a glass-ceramic composite material and its preparation method. Background Technology

[0002] Insulating materials are key materials for power grid equipment, and their performance directly affects the safe operation of the power grid and the quality of power supply.

[0003] Currently, commonly used insulation materials include ceramic insulation materials and glass insulation materials. However, traditional ceramic insulators, as heterogeneous materials with three phases coexisting, have porosity defects, which pose a risk of significant degradation in mechanical and electrical properties after long-term use; glass insulators, on the other hand, have problems such as low hardness and a tendency to spontaneously explode after tempering.

[0004] With the construction of new power systems and the continuous improvement of operating parameters, power equipment has placed higher demands on the performance of insulation materials. Therefore, high-performance insulation materials urgently need to be developed. Summary of the Invention

[0005] In view of the technical problems existing in the background art, this application provides a glass-ceramic composite material and its preparation method, aiming to provide a glass-ceramic composite material with both low dielectric loss and high breakdown strength.

[0006] In a first aspect, embodiments of this application provide a method for preparing a glass-ceramic composite material, comprising the following steps: SiO2, calcium compounds, and sodium compounds are mixed and ground to obtain a mixture. The mixture is heated until it melts to obtain a melt; The melt is poured into a mold and annealed to obtain a glass part; The glass component is subjected to a first heat treatment and a second heat treatment in sequence to obtain a glass-ceramic composite material; In the mixture, the molar percentage of Si element is n. Si The molar percentage of Ca is n Ca The molar percentage of Na is n Na n Si n Ca and n Na The following conditions must be met: n Si +n Ca +0.5n Na =100%, and n Si 40-52%, n Ca It is 32-38%; The temperature of the first heat treatment is 600~650℃, and the temperature of the second heat treatment is 650~700℃.

[0007] Secondly, embodiments of this application provide a glass-ceramic composite material, which is prepared by the preparation method described above.

[0008] The technical solution proposed in this application has the following beneficial effects: In this application, a glass-ceramic composite material with high mechanical properties, low dielectric loss, and high breakdown strength is prepared by optimizing the material formulation and preparation process. This glass-ceramic composite material combines the transparency of glass with the strength of ceramic, which can effectively solve the long-term performance degradation caused by traditional ceramic insulator composite phases and the inherent defects of spontaneous explosion of glass insulators. It helps to reduce power outage accidents caused by insulator failures and reduce potential safety hazards to national production.

[0009] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0010] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in this application will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort.

[0011] Figure 1 A photograph of the glass-ceramic composite material prepared in Example 1; Figure 2 XRD patterns of the glass-ceramic composite materials prepared in Examples 1 and 2, and Na4Ca4Si6O 18 (JCPDS-75-1687) Comparison diagram of standard cards; Figure 3 The image shows the SEM image of the glass-ceramic composite material prepared in Example 1 after etching with 2 mol% HF for 5 s. Figure 4 This is a TEM image of the glass-ceramic composite material prepared in Example 1; Figure 5 The transmittance curves are for the glass-ceramic composite materials prepared in Examples 1 and 2. Figure 6 A comparison diagram of the bending strength of the glass part obtained in step (3) of Example 1, the composite material obtained in step (4) of Example 10, and the composite material obtained in step (4) of Example 10. Figure 7Comparative load and displacement diagrams of the glass part obtained in step (3) of Example 1, the composite material obtained in step (4) of Example 10, and the composite material obtained in step (4) of Example 10. Figure 8 XRD pattern of glass-ceramic composite material prepared in Comparative Example 3 and Na4Ca4Si6O 18 (JCPDS-75-1687) Comparison diagram of standard cards; Figure 9 XRD patterns of the glass-ceramic composite material prepared in Comparative Example 5 before and after heat treatment, and Na4Ca4Si6O 18 (JCPDS-02-0961) Comparison diagram of standard cards; Figure 10 This is a photograph of the glass-ceramic composite material prepared in Comparative Example 11. Figure 11 This is a physical image of the glass-ceramic composite material prepared in Comparative Example 13. Detailed Implementation

[0012] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0013] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0014] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0015] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0016] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0017] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0018] In the description of the embodiments of this application, the term "at least one" refers to one or more, "more than one" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces). "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c," or "at least one of a, b, and c," can all represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0019] In a first aspect, embodiments of this application also propose a method for preparing a glass-ceramic composite material, the method comprising the following steps: Step S10: SiO2, calcium compound, and sodium compound are mixed and ground to obtain a mixture; wherein, the molar percentage of Si element in the mixture is n. Si The molar percentage of Ca is n Ca The molar percentage of Na is n Na n Si n Ca and n Na The following conditions must be met: n Si +n Ca+0.5n Na =100%, and n Si 40-52%, n Ca It ranges from 32% to 38%.

[0020] Step S20: Heat the mixture until it melts to obtain a melt.

[0021] Step S30: Pour the melt into a mold and anneal it to obtain a glass part.

[0022] Step S40: The glass component is subjected to a first heat treatment and a second heat treatment in sequence to obtain a glass-ceramic composite material; wherein the temperature of the first heat treatment is 600~650℃ and the temperature of the second heat treatment is 650~700℃.

[0023] In this application, a glass-ceramic composite material with high mechanical properties, low dielectric loss, and high breakdown strength is prepared by optimizing the material formulation and preparation process. This glass-ceramic composite material combines the transparency of glass with the strength of ceramic, effectively solving the long-term performance degradation caused by traditional ceramic insulator composite phases and the inherent defects of spontaneous explosion of glass insulators. It helps to reduce power outages caused by insulator failures and reduce potential safety hazards to national production. At the same time, the material is uniform internally, without internal defects such as bubbles and streaks, and without visible grains. In addition, the material has good thermal stability, specifically, it does not crack when heated in air at 150~200℃ for 30~60 minutes.

[0024] Specifically, this application prepares glass-ceramic composite materials by combining SiO2, calcium compounds, and sodium compounds in a specific ratio. The resulting glass-ceramic composite material has a silicate mineral crystalline phase (similar to pyroxene structure) as an insulator, with its interior primarily composed of strong Si-O covalent bonds forming a robust [Si6O] structure. 18 ] 12- The framework and Na-O / Ca-O ionic bonds endow this material with excellent mechanical strength and electrical properties. Furthermore, by optimizing the ratio of the three raw materials, the type, size, quantity, and distribution of the composite material's crystal phases can be controlled, thereby further improving the composite's transparency, mechanical properties, and dielectric properties. This contributes to obtaining a composite material that balances high transparency, high mechanical properties, high breakdown strength, and low dielectric loss. Excessive SiO2 and / or calcium compounds decrease the product's flexural strength and breakdown strength; excessive sodium compounds decrease the product's volume resistivity and increase the likelihood of surface crystallization. In addition, this formulation has few ingredients, a simple composition, and does not contain any other oxides or nucleating agents, which helps reduce raw material costs.

[0025] Furthermore, the method of this application optimizes the preparation process by first melting the mixture at high temperature to form an amorphous, transparent base material, and then controlling the two relatively independent processes of nucleation and crystal growth through a two-step heat treatment process at specific temperatures. This results in a large number of small and uniformly distributed crystals, and prevents the mechanical and electrical properties of the composite material from being affected by coarse grains and severe vitrification of the sample due to excessively rapid crystallization, thereby further reducing the dielectric loss of the material.

[0026] It is understood that in step S10, the calcium compound is used to provide calcium element, and can be selected from common oxides, halides, carbonates, etc. For example, the calcium compound can include, but is not limited to, one or more of calcium oxide, calcium chloride, calcium hydroxide, and calcium carbonate. The sodium compound is used to provide sodium element, and can be selected from common oxides, halides, carbonates, etc. For example, the sodium compound can include, but is not limited to, one or more of sodium oxide, sodium chloride, sodium bicarbonate, and sodium carbonate. The feed amounts of the three raw materials can meet the following condition: the molar percentage of Si element in the mixture is n. Si The molar percentage of Ca is n Ca The molar percentage of Na is n Na n Si n Ca and n Na The following conditions must be met: n Si +n Ca +0.5n Na =100%, and n Si 40-52%, n Ca The content is 32-38%. In some specific embodiments, when the sodium compound is selected from one or more of sodium oxide and sodium carbonate, the mixture consists of the following components by molar percentage: 40-52% SiO2, 32-38% calcium compound, and the balance being sodium compound; that is, the raw material of the glass-ceramic composite material consists of the following components by molar percentage: 40-52% SiO2, 32-38% calcium compound, and the balance being sodium compound. In other specific embodiments, when the sodium compound is selected from one or more of sodium chloride and sodium bicarbonate, the amount of each raw material must meet the following requirements: the sum of the molar percentage of SiO2, the molar percentage of the calcium compound, and 0.5 times the molar percentage of the sodium compound is 100%, and the molar ratio of SiO2 to the calcium compound is (40-52):(32-38).

[0027] Furthermore, in some embodiments, the molar ratio A of Na to Ca (i.e., the ratio of the molar amount of Na to the molar amount of Ca) and the molar ratio B of Ca to Si (i.e., the ratio of the molar amount of Ca to the molar amount of Si) in the raw materials of the glass-ceramic composite material satisfy the following conditions: 0.68 ≤ A ≤ 1.28, 0.6 ≤ B ≤ 1. Controlling A and B within the above range helps to further optimize the ratio of the three elements in the raw materials, regulate the size, quantity, and distribution of crystalline phase precipitation, avoid severe vitrification, make the grain size distribution more uniform, and avoid surface crystallization or localized crystallization.

[0028] Furthermore, in some embodiments, in step S10, to improve the grinding effect, ball milling can be used, and the ball milling speed is 500~700 rpm, and the ball milling time is 10~20 h. Even further, during ball milling, zirconium oxide can be used as the grinding ball, and the grinding ball gradation follows a ratio of 1 / 3 each of 1mm, 3mm, and 5mm.

[0029] In some embodiments, step S20 can be implemented as follows: holding the mixture at 1400-1500°C for 60-90 minutes to obtain a melt. Further, as a preferred embodiment, the mixture can be preheated before melting. Specifically, step S20 may include: first holding the mixture at 800-900°C for 1-2 hours, then holding it at 1400-1500°C for 60-90 minutes to obtain a melt. Thus, preheating can remove moisture from the raw materials, reducing bubbles and streaks in the glass. Especially in cases where carbonates are present in the raw materials, preheating can also complete a solid-phase reaction to release CO2 from the carbonate raw materials, further reducing bubbles and streaks in the glass.

[0030] In step S30, the annealing treatment is carried out at 500 ℃ to 550 ℃ for 5 to 10 hours, and the annealing cooling rate must not exceed 10 ℃ / minute. Controlling the annealing temperature and time within the above range helps to effectively remove stress and control the cooling rate to avoid cracking of large samples.

[0031] In some embodiments, in step S40, the temperature difference between the second heat treatment and the first heat treatment is less than or equal to 50°C; controlling the temperature difference to be no higher than 50°C helps to produce a large number of uniformly distributed microcrystals and avoids deformation or cracking of the sample during heat treatment.

[0032] In some embodiments, the duration of the first heat treatment is greater than or equal to 90 minutes, and the duration of the second heat treatment is greater than or equal to 90 minutes. Further, as a preferred embodiment, the duration of the first heat treatment is 180-1200 minutes, and the duration of the second heat treatment is 90-180 minutes.

[0033] In some embodiments, the first heat treatment step may be: heating from room temperature to the temperature of the first heat treatment at a first heating rate, and then holding at that temperature. The first heating rate is 3~10℃ / min; controlling the heating rate within this range helps to regulate the grain growth rate, ensure uniform grain growth, and avoid the formation of coarse particles or uneven crystal structures that could affect the mechanical and electrical properties of the sample.

[0034] In some embodiments, the second heat treatment step may be: heating from the temperature of the first heat treatment to the temperature of the second heat treatment at a second heating rate, and then holding at that temperature. The second heating rate is 3~10℃ / min; controlling the heating rate within this range helps to regulate the grain growth rate, ensure uniform grain growth, and avoid the formation of coarse particles or uneven crystal structures that could affect the mechanical and electrical properties of the sample.

[0035] Furthermore, in some preferred embodiments, the absolute value of the difference between the first heating rate and the second heating rate is less than or equal to 5°C / min, which helps to ensure the uniformity of grain size and avoid unnecessary secondary nucleation.

[0036] Secondly, this application also proposes a glass-ceramic composite material that can be prepared by the preparation method described above.

[0037] The glass-ceramic composite material proposed in this application has superior crystallinity, volume resistivity, dielectric properties, mechanical properties, and breakdown resistance. Specifically, in some embodiments, the crystallinity of the crystalline phase in the glass-ceramic composite material is greater than 85%; the volume resistivity of the glass-ceramic composite material at 25°C is greater than 10 Ω·cm. 11 Ω·m; the loss factor of the glass-ceramic composite material at 1 MHz is less than or equal to 1.0 × 10⁻⁶. -3 The Vickers hardness of the glass-ceramic composite material is greater than 600 HV; the breakdown strength of the glass-ceramic composite material is greater than 20 kV / mm; and the flexural strength of the glass-ceramic composite material is greater than 130 MPa.

[0038] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0039] Example 1 (1) Take 50.5 mol% SiO2, 34 mol% CaCO3 and 15.5 mol% Na2CO3, mix them evenly, and then pour them into a ball mill jar for ball milling to obtain a mixture. The ball milling speed is 600 rpm and the time is 10 h. Zirconia is used as the ball milling ball, and the gradation follows the principle of 1 / 3 each of 1 mm, 3 mm and 5 mm.

[0040] (2) The mixture is placed into a platinum crucible and then into a muffle furnace. It is kept at 850°C for 2 hours, and then transferred to a high-temperature resistance furnace and kept at 1450°C for 90 minutes to obtain the melt.

[0041] (3) Pour the melt into a preheated brass mold and anneal it at 550 °C for 10 hours to obtain a glass part.

[0042] (4) The glass part is cut into thin sheet samples, and then subjected to a first heat treatment and a second heat treatment in sequence to obtain a glass-ceramic composite material. The first heat treatment process is as follows: the temperature is increased from room temperature to 600℃ at a heating rate of 5℃ / min, and then held at that temperature for 20h. The second heat treatment process is as follows: the temperature is increased from 600℃ to 650℃ at a heating rate of 5℃ / min, and then held at that temperature for 2h.

[0043] The physical image of the glass-ceramic composite material (approximately 1 mm thick) prepared in this embodiment is shown below. Figure 1 As shown, the composite material has good transmittance, and the grid lines of the background paper are clearly visible.

[0044] Furthermore, the composite material was observed using transmission electron microscopy (TEM), and the results are as follows: Figure 4 As shown, Figure 4 (a) and (b) are TEM and HRTEM images, respectively. The images show lattice fringes of 0.184 nm and 0.186 nm, corresponding to Na₄Ca₄Si₆O₂. 18 The (404), (107) and (101) crystal planes.

[0045] Examples 2 to 5 The schemes of Examples 2 to 5 are basically the same as those of Example 1, except that the raw material formulas in Examples 2 to 5 are as shown in Table 1. All other parameters and conditions remain unchanged.

[0046] Table 1 (%: molar percentage content)

[0047] Example 6 This embodiment is basically the same as Embodiment 4, except that sodium carbonate is replaced with twice the molar amount of sodium chloride, i.e., the molar ratio of SiO2 to CaCO3 is 49:32.5, and the sum of the molar percentages of SiO2 (49%), CaCO3 (32.5%), and NaCl (37% × 0.5 = 18.5%) is 100%, A = 1.14, B = 0.66. All other parameters and conditions remain unchanged.

[0048] Example 7 (1) Take 50.5 mol% SiO2, 34 mol% CaO and 15.5 mol% Na2O, mix them evenly, and then pour them into a ball mill jar for ball milling to obtain a mixture. The ball milling speed is 600 rpm and the time is 10 h. Zirconia is used as the ball milling ball, and the gradation follows the principle of 1 / 3 each of 1 mm, 3 mm and 5 mm.

[0049] (2) The mixture is placed into a platinum crucible and then into a muffle furnace. It is kept at 800°C for 2 hours, and then transferred to a high-temperature resistance furnace and kept at 1400°C for 90 minutes to obtain the melt.

[0050] (3) Pour the melt into a preheated brass mold and anneal it at 550 °C for 10 hours to obtain a glass part.

[0051] (4) The glass part is cut into thin sheet samples, and then subjected to a first heat treatment and a second heat treatment in sequence to obtain a glass-ceramic composite material. The first heat treatment process is as follows: the temperature is increased from room temperature to 600℃ at a heating rate of 5℃ / min, and then held at that temperature for 20h. The second heat treatment process is as follows: the temperature is increased from 600℃ to 650℃ at a heating rate of 5℃ / min, and then held at that temperature for 2h.

[0052] Example 8 (1) Take 52 mol% SiO2, 34.9 mol% CaCl2 and 13.1 mol% Na2CO3 (A=0.75, B=0.67), mix them evenly, and then pour them into a ball mill jar for ball milling to obtain a mixture. The ball milling speed is 600 rpm and the time is 10 h. Zirconia is used as the ball milling ball, and the gradation follows the principle of 1 / 3 each of 1 mm, 3 mm and 5 mm.

[0053] (2) The mixture is placed into a platinum crucible and then into a muffle furnace. It is kept at 900°C for 1 hour, and then transferred to a high-temperature resistance furnace and kept at 1550°C for 90 minutes to obtain the melt.

[0054] (3) Pour the melt into a preheated brass mold and anneal it at 550 °C for 5 hours to obtain a glass part.

[0055] (4) The glass part is cut into thin sheet samples, and then subjected to a first heat treatment and a second heat treatment in sequence to obtain a glass-ceramic composite material. The first heat treatment process is as follows: the temperature is increased from room temperature to 650°C at a heating rate of 10°C / min, and then held at that temperature for 20 hours. The second heat treatment process is as follows: the temperature is increased from 650°C to 700°C at a heating rate of 10°C / min, and then held at that temperature for 2 hours.

[0056] Example 9 (1) Take 42 mol% SiO2, 38 mol% CaCO3 and 20 mol% Na2CO3 (A=1.05, B=0.90), mix them evenly, and then pour them into a ball mill jar for ball milling to obtain a mixture. The ball milling speed is 700 rpm and the time is 15 h. Zirconia is used as the ball milling ball, and the gradation follows the principle of 1 / 3 each of 1 mm, 3 mm and 5 mm.

[0057] (2) The mixture is placed into a platinum crucible and then into a muffle furnace. It is kept at 850°C for 2 hours, and then transferred to a high-temperature resistance furnace and kept at 1500°C for 60 minutes to obtain the melt.

[0058] (3) Pour the melt into a preheated brass mold and anneal it at 500 °C for 10 hours to obtain a glass part.

[0059] (4) The glass part is cut into thin sheet samples, and then subjected to a first heat treatment and a second heat treatment in sequence to obtain a glass-ceramic composite material. The first heat treatment process is as follows: the temperature is increased from room temperature to 600℃ at a heating rate of 3℃ / min, and then held at that temperature for 20h. The second heat treatment process is as follows: the temperature is increased from 600℃ to 680℃ at a heating rate of 3℃ / min, and then held at that temperature for 2h.

[0060] Example 10 The scheme in this embodiment is basically the same as that in Embodiment 1, except that the temperature of the first heat treatment is changed to 640℃ and the temperature of the second heat treatment is changed to 690℃. All other parameters and conditions remain unchanged.

[0061] Example 11 The scheme in this embodiment is basically the same as that in embodiment 10, except that in this embodiment, the temperature is not maintained at 850°C for 2 hours. All other parameters and conditions remain unchanged.

[0062] Comparative Example 1 This comparative example is basically the same as Example 1, except that the raw material formula is: SiO2 50mol%, CaCO3 23mol%, Na2CO3 27mol%, A=2.35, B=0.46. All other parameters and conditions remain unchanged.

[0063] Comparative Example 2 This comparative example is basically the same as Example 1, except that the raw material formula is: SiO2 59 mol%, CaCO3 23 mol%, Na2CO3 18 mol%, A=1.57, B=0.39. All other parameters and conditions remain unchanged.

[0064] Comparative Example 3 This comparative example is essentially the same as Example 2, except that, based on the raw material formulation of Example 2, 3.5 wt.% ZrO2 and 2 wt.% B2O3 were added to this comparative example (i.e., the mass of ZrO2 accounts for 3.5% of the total mass of the mixture composed of 50 mol% SiO2, 23 mol% CaCO3, and 27 mol% Na2CO3, and the mass of B2O3 accounts for 2% of the total mass of the mixture). Apart from this, all other parameters and conditions remain unchanged.

[0065] Comparative Example 4 This comparative example is basically the same as Example 1, except that the raw material formula is: SiO2 60mol%, CaCO3 25mol%, Na2CO3 15mol%, A=1.2, B=0.42; correspondingly, the temperature of the second heat treatment is changed to 700℃ and the time is changed to 2h. Other than that, all other parameters and conditions remain unchanged.

[0066] Comparative Example 5 This comparative example is basically the same as Example 1, except that the raw material formula is: SiO2 52 mol%, CaCO3 30 mol%, Na2CO3 18 mol%, A=1.2, B=0.58; correspondingly, the temperature of the second heat treatment is changed to 700℃ and the time is changed to 2 hours. Other than that, all other parameters and conditions remain unchanged.

[0067] Comparative Example 6 This comparative example is basically the same as Example 1, except that the raw material formula is: SiO2 45mol%, CaCO3 40mol%, Na2CO3 15mol%, A=0.75, B=0.89. All other parameters and conditions remain unchanged.

[0068] After the second heat treatment in step (4), the composite material of this comparative example exhibited localized crystallization and atomization.

[0069] Comparative Example 7 This comparative example is basically the same as Example 1, except that the raw material formula is: SiO2 40mol%, CaCO3 45mol%, Na2CO3 15mol%, A=0.67, B=1.12. All other parameters and conditions remain unchanged.

[0070] In this comparative example, during step (3), crystallization occurred when the melt was poured into the brass mold, and no glass was formed.

[0071] Comparative Example 8 This comparative example is basically the same as Example 1, except that the raw material formula is: SiO2 40mol%, CaCO3 32mol%, Na2CO3 28mol%, A=1.75, B=0.8. All other parameters and conditions remain unchanged.

[0072] In step (3) of this comparative example, it was found that the melt had poor glass-forming ability, strong tendency to self-crystallize, and devitrification occurred.

[0073] Comparative Example 9 This comparative example is basically the same as Example 1, except that the raw material formula is: SiO2 40mol%, CaCO3 35mol%, Na2CO3 25mol%, A=1.43, B=0.875. All other parameters and conditions remain unchanged.

[0074] After the second heat treatment, the composite material of this comparative example showed severe crystallization on the sample surface and local cracking at the edges of the crystallization points.

[0075] Comparative Example 10 This comparative example is basically the same as Example 1, except that the raw material formula is: SiO2 40mol%, CaCO3 30mol%, Na2CO3 30mol%, A=2, B=0.75. All other parameters and conditions remain unchanged.

[0076] In this comparative example, partial devitrification occurred during the casting process in step (3), and uncontrollable crystallization occurred after the second heat treatment, resulting in porcelainization of the sample and very low transmittance.

[0077] Comparative Example 11 This comparative example is basically the same as Example 3, except that the heating rate is adjusted to 15°C / minute during both the first and second heat treatments. All other parameters and conditions remain unchanged.

[0078] A physical image of the composite material prepared in this comparative example is shown below. Figure 10 As shown, due to the excessively rapid heating rate, the grains grow rapidly, forming a coarse and uneven crystal structure, resulting in visible grains and severe devitrification of the product.

[0079] Comparative Example 12 This comparative example is basically the same as Example 3, except that in this example, the temperature of the first heat treatment is changed to 610℃, the temperature of the second heat treatment is changed to 700℃, and the temperature difference between the two heat treatments is greater than 50℃. All other parameters and conditions remain unchanged.

[0080] The composite material prepared in this comparative example is consistent with that in comparative example 11. Due to the large temperature difference between the two heat treatment steps, a coarse and uneven crystal structure is formed, and milky white particles visible to the naked eye are precipitated, resulting in severe devitrification of the product.

[0081] Comparative Example 13 This comparative example is essentially the same as Example 10, except that an additional 5 wt% of nucleating agent ZrO2 is added to the formulation. All other parameters and conditions remain unchanged.

[0082] The composite material prepared in this comparative example showed a significant increase in viscosity upon cooling and casting after being held at 1450℃ for 90 minutes. Furthermore, after cooling and annealing, the sample exhibited noticeable milky turbidity in certain areas. This may be due to an enhanced tendency for crystallization within the sample, resulting in the precipitation of tetragonal zirconium oxide or zircon, which disrupted the sample's homogeneity. A photograph of the actual product from this comparative example is shown below. Figure 11 As shown.

[0083] Comparative Example 14 This comparative example is basically the same as Example 11, except that in this comparative example, the temperature of the first heat treatment is changed to 630°C and the temperature of the second heat treatment is changed to 700°C. All other parameters and conditions remain unchanged.

[0084] After casting, the composite material prepared in this comparative example showed some bubble streaks inside the sample, and the precipitation of grains after heat treatment was consistent with that in comparative example 12.

[0085] Performance testing (a) The glass-ceramic composite materials prepared in Examples 1, 2, 3, and 5 were subjected to X-ray diffraction analysis (XRD). The test results are as follows: Figure 2 , Figure 8 and Figure 9 As shown in the figure, the horizontal axis 2θ represents the diffraction angle, and the vertical axis intensity represents the diffraction intensity.

[0086] Results Analysis: The X-ray diffraction patterns of the composite materials in Examples 1 and 2 are similar to those of Na4Ca4Si6O. 18 The (JCPDS-75-1687) standard card showed consistent contrast and no other impurities, indicating that the ceramic phase in the composite material obtained after the two-step heat treatment was extremely pure. Furthermore, based on this XRD pattern, calculations showed that the crystallinity of the composite materials in Examples 1 and 2 was greater than 85%.

[0087] The XRD pattern of Comparative Example 3 shows that its main crystalline phase is Na4Ca4Si6O. 18 However, impurity peaks of Na2Ca3Si2O8 appeared near 15°, indicating that although Na4Ca4Si6O could still be formed after the addition of other components. 18 The main crystalline phase, but prone to the formation of other impurity phases. Small amounts of ZrO2 and B2O3, and Ca are added. 2+ Na + Modified ion interactions alter the distribution of ions in the silicate network, leading to the generation of other impurity phases and changes in the properties of the sample.

[0088] The XRD pattern of Comparative Example 5 shows that its main crystalline phase is Na2Ca2Si3O9, but impurity peaks of Na2CaSi3O8 appear near 32° and 33°, indicating that when CaCO3 is below 32 mol%, the main crystalline phase changes and other impurity phases are easily generated.

[0089] (ii) The composite material prepared in Example 1 was etched with 2 mol% HF for 5 seconds to obtain the etched composite material, which was then inspected using a scanning electron microscope (SEM). Figure 3 As shown, Figures (a), (b), and (c) are SEM images at different magnifications.

[0090] Results analysis: Figure (a) shows that after the sample was soaked in 2 mol% HF solution for 5 seconds, the sample surface became a scattered and irregular surface. Figures (b) and (c) show that the composite material precipitated a large number of uniformly sized grains.

[0091] (III) Performance testing of each embodiment and comparative example Sample preparation: The material to be tested was cut into 10×10×1 mm and 20×20×1 mm sheet samples, and the surface was smoothed using a metallographic polishing machine. After cleaning and drying, the samples were tested, and the results are as follows. Figure 5 , Figure 6 , Figure 7 As shown in Tables 2 to 4. Figure 5 In the diagram, the horizontal axis represents wavelength, and the vertical axis represents transmittance. Figure 6 In the figure, the horizontal axis "sample" represents the sample, and the vertical axis "bending strength" represents the bending strength. Figure 7 In the diagram, the horizontal axis "shift" represents displacement, and the vertical axis "stress" represents load.

[0092] 1. Transparency Test: First, visually inspect the sample to determine its transparency level (severe opacity, porcelain-like opacity, moderate transparency, good transparency). For samples with a transparency level of moderate or higher, a UV spectrophotometer can be used for transmittance testing. The criteria for judging transparency are as follows: Severe devitrification: Milky white flocculent material appears locally in the sample, and the light source is almost invisible when exposed to light.

[0093] Vitrification devitrification: Partial vitrification and peeling occur on the sample surface, and the entire sample appears as a milky white ceramic.

[0094] Through general observation: The sample exhibits good crystallization, with no other visible precipitates inside, and the light source is visible when held up to the light.

[0095] Good visibility: The sample crystallization is good and not much different from the precursor. The light source is clearly visible when the light is applied.

[0096] 2. Crystallinity test: The crystallinity of the samples was measured using a D8 Advance X-ray diffractometer and calculated using the Scherrer formula.

[0097] 3. Vickers hardness test: Vickers hardness is measured using a microhardness tester (DHV-1000-CCD, Beijing), with a standard load of 0.5 kg (load holding time: 10 s).

[0098] 4. Dielectric constant test: The dielectric properties of the sample were tested at room temperature using a PolyKPK-CPT1705 low-temperature dielectric tester from the United States. The test range was 40 Hz-110 MHz, and the radius of the silver paste circular electrode was r=6 mm.

[0099] 5. Volume resistivity test: The volume resistivity of the sample at room temperature (25 ℃) was tested using a resistivity meter.

[0100] 6. Bending strength test: The bending strength of the material is tested by an electronic universal testing machine with a load accuracy of ≥ ±0.5% and an effective data sampling frequency of not less than 2000 Hz.

[0101] 7. Loss factor test: The dielectric constant and dielectric loss of the sample are tested at room temperature using a PolyKPK-CPT1705 low-temperature dielectric tester from the United States. The tangent of the two values ​​is then calculated, which is the loss factor.

[0102] 8. Breakdown strength test: The electrical breakdown strength test is carried out using a precision electrical breakdown tester (ZJC-50E), with the voltage boost rate set to 0.5 kV / minute (DC).

[0103] (1) The glass parts (i.e. the material before the two-step heat treatment, denoted as PG) and the composite material (denoted as GC) obtained in step (3) of Examples 1 to 5 were subjected to performance tests, and the results were recorded in Table 2.

[0104] (2) The composite materials prepared in Examples 6 to 10 and Comparative Examples 1 to 5 were subjected to performance tests, and the results were recorded in Tables 3 and 4.

[0105] Table 2

[0106] Table 3

[0107] Table 4

[0108] Combining the test results in Tables 2 to 4 with the attached figures and the phenomena observed during the preparation process of Comparative Examples 6 to 14, it can be seen that: The glass-ceramic composite materials prepared in each embodiment all exhibit high transmittance, high crystallinity, high Vickers hardness, high dielectric constant, high volume resistivity, high breakdown strength, high flexural strength, and low loss. In contrast, Comparative Examples 3 and 13, after adding other components, showed problems such as the formation of impurity phases or decreased sample uniformity. Comparative Example 3 also suffered from decreased transmittance, reduced Vickers hardness, and decreased flexural strength. The materials in Comparative Examples 1-2 and 4-5 exhibited problems such as vitrification devitrification, inconsistent crystal phases, or impure crystal phases, and showed a decline in mechanical properties. Even worse, the materials in Comparative Examples 6-10 showed problems such as decreased glass-forming ability, uncontrolled crystallization, and localized cracking during preparation. In summary, this demonstrates that the raw materials for glass-ceramic composite materials must meet the following conditions: the molar percentage of Si element is n. Si The molar percentage of Ca is n Ca The molar percentage of Na is n Na n Si n Ca and n Na The following conditions must be met: n Si +n Ca +0.5n Na =100%, and n Si 40-52%, n Ca With a concentration of 32-38%, it helps to balance and improve the various properties of composite materials, giving them good transparency, high mechanical strength, high breakdown strength, high volume resistivity, and low dielectric loss.

[0109] Furthermore, by comparing Example 3 with Comparative Examples 11, 12, and 14, it can be seen that by controlling the heating rate and the temperature difference between the two heat treatments, it is helpful to regulate the grain growth rate, ensure uniform grain growth, and avoid the formation of coarse particles or uneven crystal structures.

[0110] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A method for preparing a glass-ceramic composite material, characterized in that, Includes the following steps: SiO2, calcium compounds, and sodium compounds are mixed and ground to obtain a mixture. The mixture is heated until it melts to obtain a melt; The melt is poured into a mold and annealed to obtain a glass part; The glass component is subjected to a first heat treatment and a second heat treatment in sequence to obtain a glass-ceramic composite material; In the mixture, the molar percentage of Si element is n. Si The molar percentage of Ca is n Ca The molar percentage of Na is n Na n Si n Ca and n Na The following conditions must be met: n Si +n Ca +0.5n Na =100%, and n Si 40-52%, n Ca It is 32-38%; The temperature of the first heat treatment is 600~650℃, and the temperature of the second heat treatment is 650~700℃.

2. The preparation method according to claim 1, characterized in that, In the raw materials of the glass-ceramic composite material, the molar ratio A of Na to Ca and the molar ratio B of Ca to Si satisfy the following conditions: 0.68≤A≤1.28, 0.6≤B≤1.

3. The preparation method according to claim 1, characterized in that, The calcium compound includes one or more of calcium oxide, calcium chloride, calcium hydroxide, and calcium carbonate; and / or, The sodium compound includes one or more of sodium oxide, sodium chloride, sodium bicarbonate, and sodium carbonate; and / or, The temperature difference between the second heat treatment and the first heat treatment is less than or equal to 50°C; and / or, The first heat treatment lasts for 90 minutes or more, and the second heat treatment lasts for 90 minutes or more; and / or, The temperature is increased to the temperature of the first heat treatment at a first heating rate of 3~10℃ / min; and / or, The temperature is increased to the temperature of the second heat treatment at a second heating rate of 3~10℃ / min.

4. The preparation method according to claim 3, characterized in that, When the sodium compound is selected from one or more of sodium oxide and sodium carbonate, the mixture consists of the following components by molar percentage: 40-52% SiO2, 32-38% calcium compound, and the balance is sodium compound. When the sodium compound is selected from one or more of sodium chloride and sodium bicarbonate, the sum of the molar percentage of SiO2, the molar percentage of the calcium compound, and 0.5 times the molar percentage of the sodium compound is 100%, and the molar ratio of SiO2 to the calcium compound is (40~52):(32~38).

5. The preparation method according to claim 3, characterized in that, The absolute value of the difference between the first heating rate and the second heating rate is less than or equal to 5°C / minute.

6. The preparation method according to claim 1, characterized in that, The step of heating the mixture to a melt to obtain a melt includes: holding the mixture at 1400~1500℃ for 60~90 minutes to obtain a melt.

7. The preparation method according to claim 6, characterized in that, The step of heating the mixture to a melt to obtain a melt includes: first, keeping the mixture at 800~900℃ for 1~2 hours, and then keeping it at 1400~1500℃ for 60~90 minutes to obtain a melt.

8. The preparation method according to claim 1, characterized in that, The annealing process is carried out at 500℃~550℃ for 5~10 hours, and the annealing cooling rate shall not exceed 10℃ / minute.

9. A glass-ceramic composite material, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 8.

10. The glass-ceramic composite material according to claim 9, characterized in that, The glass-ceramic composite material has a crystallinity greater than 85%; and / or, The glass-ceramic composite material has a volume resistivity greater than 10 at 25°C. 11 Ω·m; and / or, The loss factor of the glass-ceramic composite material at 1 MHz is less than or equal to 1.0 × 10⁻⁶. -3 ; and / or, The Vickers hardness of the glass-ceramic composite material is greater than 600 HV; and / or, The breakdown strength of the glass-ceramic composite material is greater than 20 kV / mm; and / or, The flexural strength of the glass-ceramic composite material is greater than 130 MPa.

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