NBAS microcrystalline glass powder, NBAS glass powder and preparation method

Abstract

The invention discloses NBAS glass ceramic powder, NBAS glass powder and a preparation method, and relates to the technical field of inorganic non-metallic materials, and the preparation method of the NBAS glass ceramic powder comprises the following steps: providing first sol, the raw materials comprise the following components in parts by mass: 3-46.5 parts of sodium bicarbonate, 20-40 parts of boric acid, 30-119 parts of tetraethoxysilane, 8-43 parts of aluminum nitrate nonahydrate, 0-47 parts of zinc nitrate dihydrate and 0-10 parts of a nucleating agent. And drying the first sol, heating to 700-900 DEG C at a heating rate of 3-5 DEG C / min, preserving heat for 0.5-2 hours, naturally cooling, and crushing and ball-milling the obtained NBAS glass ceramic block to obtain the NBAS glass ceramic powder. The method provided by the invention is low in melting temperature, relatively low in energy consumption and simple in steps, and the prepared NBAS microcrystalline glass powder has relatively low thermal expansion coefficient, dielectric constant and dielectric loss.

Description

Technical Field

[0001] This invention relates to the field of inorganic non-metallic materials technology, and in particular to an NBAS microcrystalline glass powder, NBAS glass powder, and its preparation method. Background Technology

[0002] Sodium borosilicate glass (Na2O-B2O3-Al2O3-SiO2, or NBAS) and glass-ceramics, due to their absence of expensive lithium in their composition and the combination of the excellent low melting point of borosilicate glass and the good mechanical and chemical stability of aluminosilicate systems, have shown great application potential in low-temperature co-fired ceramic (LTCC) substrates, electronic packaging materials, high-performance ceramic binders, and decorative materials. Ideal electronic packaging materials require a low coefficient of thermal expansion (CTE), low dielectric constant and loss (to reduce signal transmission delay and energy loss), a sufficiently low sintering temperature (typically below 900 °C) to match low-cost electrodes, and good mechanical strength and chemical stability, all matching silicon chips or common metal conductors (such as silver and copper). Furthermore, in some applications (such as high-end decoration and specific optical devices), controllable opacity and a stable white appearance are also required.

[0003] Currently, the preparation of NBAS glass powder and NBAS microcrystalline glass powder mainly relies on the traditional high-temperature melting-quenching-mechanical pulverization method. While this method is technologically mature, it faces a series of fundamental and insurmountable defects, severely restricting the development and application of high-performance, functionalized NBAS powders: (1) Poor component uniformity and volatilization of key components. During high-temperature melting (usually >1400 ℃), alkali metal oxides (Na2O) and boron oxides (B2O3) are highly volatile, causing the chemical composition of the final product to deviate significantly from the design formula, resulting in instability of material properties (such as melting point and coefficient of expansion). At the same time, factors such as melt viscosity and phase separation tendency make it difficult to achieve uniform mixing of refractory components such as Al2O3 and SiO2 at the atomic / molecular scale. The compositional fluctuations at the microscale pose a hidden danger for the subsequent precipitation of unexpected crystalline phases (such as coarse cristobalite).

[0004] (2) High melting temperature, high energy consumption, and inability to precisely control the crystal phase. To obtain homogeneous glass, traditional processes require extremely high melting temperatures (usually >1400 ℃), resulting in high energy consumption and severe corrosion of refractory crucibles. The crystallization process of glass powder obtained through melting and quenching is a diffusion-controlled solid-state phase transition. Due to the uneven composition of the initial powder and the high surface energy of the particles, crystal nuclei often form non-uniformly on the particle surface or at defects, which easily leads to coarse grains, excessively high or low crystallinity, and difficulty in precisely controlling the main crystal phase. This is extremely unfavorable for materials that require low-expansion β-quartz solid solutions or similar structural crystal phases.

[0005] (3) It is difficult to achieve both low melting temperature and low coefficient of thermal expansion at the same time: Traditional processes make it difficult to achieve "low melting" and "low expansion" in the same material. Introducing a large amount of B2O3 and Na2O can effectively reduce the glass softening point and melting temperature, but it often increases the coefficient of thermal expansion of the material and reduces its chemical stability; in order to obtain a low coefficient of expansion, it is necessary to promote the precipitation of specific crystal phases (such as crystal phases containing Al and Si), which usually requires a higher processing temperature.

[0006] (4) Achieving a white opaque effect is difficult and unstable. To achieve a white opaque effect, it is usually necessary to introduce nucleating agents (such as TiO2, ZrO2) and induce a large number of microcrystals or phase separation during heat treatment. In the traditional melting method, it is difficult to ensure the uniformity of the distribution of nucleating agents, and they are prone to valence state changes at high temperatures (such as TiO2). 4+ Partially restored to Ti 3+ This can cause the glass matrix to become discolored (e.g., yellowish-brown), which in turn impairs whiteness. Furthermore, the grinding process itself may introduce structural defects, leading to unintended coloring reactions during subsequent heat treatment.

[0007] To overcome the aforementioned shortcomings, the sol-gel method, as a low-temperature chemical synthesis route, has attracted widespread attention. This method involves molecular-level mixing of precursors in solution, theoretically achieving extremely high component homogeneity and significantly reducing the synthesis temperature. However, current research on the preparation of NBAS system materials using the sol-gel method still has significant limitations: (1) Most studies focus on the preparation of porous materials, thin films or specific functional glasses (such as hydrated glass), while there is a lack of research on dense, low-expansion, low-dielectric-loss microcrystalline glass powders, especially microcrystalline glass powders with opacifying effect.

[0008] (2) The process often draws on traditional ideas, namely, first prepare dry gel, then calcine it at high temperature to obtain glass powder, and finally carry out crystallization treatment. The steps are complicated and fail to give full play to the unique potential of sol-gel precursor in controllable crystallization. It is impossible to achieve the synergistic regulation of key properties of the NBAS system such as low melting point, low expansion, low dielectric and opacity whiteness.

[0009] Therefore, developing a novel preparation method that can fundamentally solve the problem of component uniformity, achieve low-temperature synthesis, and precisely control crystallization behavior and microstructure is crucial for obtaining high-performance, multifunctional NBAS glass powder and microcrystalline glass powder. Summary of the Invention

[0010] Based on the shortcomings of the prior art, the purpose of this invention is to provide NBAS microcrystalline glass powder, NBAS glass powder, and preparation method, aiming to solve the problems of poor component uniformity, volatilization of key components, high melting temperature, and high energy consumption in the existing high-temperature melting-quenching-mechanical crushing method for preparing NBAS powder. At the same time, it solves the problem that the existing sol-gel method for preparing NBAS powder requires first preparing a dry gel, then calcining it at high temperature to obtain glass powder, and finally crystallizing it, which is a complicated process.

[0011] The technical solution of the present invention is as follows: In a first aspect, the present invention provides a method for preparing NBAS microcrystalline glass powder, comprising the following steps: A first sol is provided, the raw materials of which include the following components in parts by weight: 3-46.5 parts of sodium bicarbonate, 20-40 parts of boric acid, 30-119 parts of tetraethyl orthosilicate, 8-43 parts of aluminum nitrate nonahydrate, 0-47 parts of zinc nitrate dihydrate, and 0-10 parts of nucleating agent, wherein the nucleating agent is not 0 parts. After drying the first sol, a first dry gel is obtained; The first dry gel was heated to 700-900 ℃ at a heating rate of 3-5 ℃ / min and held at that temperature for 0.5-2 h. After natural cooling, NBAS microcrystalline glass block was obtained. The NBAS microcrystalline glass block is crushed and ball-milled to obtain NBAS microcrystalline glass powder.

[0012] Optionally, the preparation method of the first sol includes the following steps: Sodium bicarbonate, glacial acetic acid, zinc acetate dihydrate, boric acid, aluminum nitrate nonahydrate, and water are mixed to obtain solution A. Tetraethyl orthosilicate was added to a mixed solution consisting of anhydrous ethanol, concentrated nitric acid, and water. After stirring, solution B was obtained. The nucleating agent was added to a mixed solution consisting of anhydrous ethanol, concentrated nitric acid, and water, and after stirring, solution C was obtained. Liquid B is added to liquid A, then liquid C is added, and after stirring, the first sol is obtained.

[0013] Optionally, the nucleating agent comprises an aqueous solution of tetrabutyl titanate and / or zirconium acetate; The first sol was dried at a temperature of 100~200 °C to obtain the first dry gel.

[0014] In a second aspect, the present invention provides an NBAS microcrystalline glass powder, wherein the powder is prepared by the preparation method described above.

[0015] Optionally, the chemical composition of the NBAS microcrystalline glass powder includes Na2O, B2O3, SiO2, Al2O3, ZnO and a nucleating agent, wherein the nucleating agent is TiO2 and / or ZrO2; The mass ratio of Na2O, B2O3, SiO2, Al2O3, ZnO to the nucleating agent is (5~15):(30~50):(30~40):(5~10):(0~15):(0~5), and the nucleating agent component is not 0.

[0016] A third aspect of the present invention provides a method for preparing NBAS glass powder, comprising the following steps: A second sol is provided, the raw materials of which include the following components in parts by weight: 3-46.5 parts sodium bicarbonate, 20-40 parts boric acid, 30-119 parts tetraethyl orthosilicate, 8-43 parts aluminum nitrate nonahydrate, and 0-47 parts zinc nitrate dihydrate; After drying the second sol, a second dry gel is obtained; The second dry gel was heated to 700-900 ℃ at a heating rate of 3-5 ℃ / min and held at that temperature for 0.5-2 h. After natural cooling, NBAS glass blocks were obtained. The NBAS glass block is crushed and ball-milled to obtain NBAS glass powder.

[0017] Optionally, the second sol is dried at a temperature of 100~200 °C to obtain a second dry gel.

[0018] Optionally, the preparation method of the second sol includes the following steps: Sodium bicarbonate, glacial acetic acid, zinc acetate dihydrate, boric acid, aluminum nitrate nonahydrate, and water are mixed to obtain solution A. Tetraethyl orthosilicate was added to a mixed solution consisting of anhydrous ethanol, concentrated nitric acid, and water. After stirring, solution B was obtained. The B solution is added to the A solution, and after stirring, a second sol is obtained.

[0019] In a fourth aspect, the present invention provides an NBAS glass powder, wherein the powder is prepared by the preparation method described above.

[0020] Optionally, the chemical composition of the NBAS glass powder includes Na2O, B2O3, SiO2, Al2O3 and ZnO, wherein the mass ratio of Na2O, B2O3, SiO2, Al2O3 and ZnO is (5~15):(30~50):(30~40):(5~10):(0~5).

[0021] Beneficial effects: This invention uses a sol-gel method combined with an integrated heat treatment strategy to prepare NBAS microcrystalline glass and NBAS glass, which has the following advantages: (1) It possesses molecular-level uniformity and a low melting temperature. Specifically, this invention uses tetraethyl orthosilicate, boric acid, sodium bicarbonate, aluminum nitrate, etc., in specific proportions as raw materials to form a three-dimensional network gel through hydrolysis-condensation reaction, ensuring that elements such as Na, B, Al, and Si achieve uniform distribution at the molecular / atomic scale. This extreme uniformity fundamentally eliminates the component segregation caused by phase separation or volatilization in existing high-temperature melting methods, laying the foundation for obtaining materials with highly reproducible properties. Because the composition is uniform and the content of B2O3 and Na2O is precisely controlled, the softening point of the glass phase is significantly reduced. Therefore, the decomposition of the precursor and the formation and densification of the glass network can be completed at a temperature of only a few hundred degrees Celsius (700~900 ℃), avoiding the high-energy-consuming melting process above 1400 ℃ in traditional processes, significantly reducing energy consumption and production costs, and completely solving the problem of high-temperature volatilization of B2O3 and Na2O, making it possible to accurately realize low-melting-point formulations.

[0022] (2) Integrated heat treatment enables precise control of structural properties. This invention abandons the traditional two-step method of "preparing glass powder first, then external crystallization" and innovatively performs integrated heat treatment on the dry gel. In this process, the decomposition and removal of inorganic and organic matter, the formation and densification of the inorganic glass network, the induction effect of the nucleating agent, and the precipitation and growth of the target crystal phase are integrated into a continuous and controllable thermal program, and the steps are simple. Specifically, by utilizing the high activity and uniform composition of sol and gel, and through precise control of the heat treatment regime, the glass matrix is ​​first fully densified at a relatively low temperature (the lower temperature in the programmed heating process). Then, during the cooling process, uniform and numerous nuclei are induced in the nucleating agent enrichment area, and the uniformly distributed nucleating agent (TiO2 / ZrO2) can effectively reduce the crystallization activation energy and promote the uniform precipitation of subsequent nanocrystals. This "densification first, then internal growth" approach allows for the preferential precipitation of Al and Si-rich, low-expansion crystalline phases (such as nepheline solid solution or similar structures), while confining elements like B and Na within the residual glassy phase to maintain low melting points. This cleverly resolves the traditional contradiction between "low expansion" and "low melting point." In other words, by inducing the precipitation of a large number of low-expansion crystalline phases and controlling their nanoscale and uniform distribution, the material can achieve a low overall coefficient of thermal expansion, ensuring good compatibility with semiconductor chips. Furthermore, the highly dense microstructure, pure crystalline phases, and controlled residual glassy phase collectively endow the material with excellent high-frequency dielectric properties.

[0023] (3) Controllable achievement of opacification effect and white appearance. In this invention, a specific amount of TiO2 and / or ZrO2 is incorporated into the composition of NBAS glass as nucleating agents. In the highly uniform precursor prepared by the sol-gel method, these nucleating agents are uniformly dispersed in the form of ions or nanoclusters. During the integrated heat treatment process, they first induce uniform, high-density liquid-liquid phase separation or directly form primary crystal phases (such as ZrTiO4), and then the main crystal phase (such as crystal phases containing Al and Si) precipitates, ultimately forming numerous crystal-glass phase interfaces with sizes comparable to the wavelength of visible light within the material. Light undergoes a strong scattering effect at these interfaces, thereby producing an excellent opacification effect. More importantly, due to the high purity and uniformity of the starting materials in this invention, and the fact that this invention avoids the high-temperature reducing atmosphere and long-term heat treatment of the traditional melting method, Ti ions in this invention can be stably maintained in a high valence state (Ti 4+ This effectively suppressed the effects of Ti. 3+ The presence of substances such as yellowish-brown ensures that the final microcrystalline glass powder presents a pure white color.

[0024] Therefore, this invention organically combines the sol-gel method with an integrated heat treatment process, employing a low melting temperature and low energy consumption. It also ensures uniform composition of the NBAS microcrystalline glass powder. Furthermore, the preparation of NBAS microcrystalline glass powder can be achieved through a single low-temperature melting and recrystallization process, simplifying the steps. The resulting NBAS microcrystalline glass powder exhibits a low coefficient of thermal expansion, high flexural strength, and low dielectric constant and dielectric loss. This invention effectively solves the problems of poor component uniformity, volatilization of key components, high melting temperature, and high energy consumption inherent in existing high-temperature melting-quenching-mechanical pulverization methods for preparing NBAS powder. It also addresses the cumbersome process of existing sol-gel methods, which require first preparing a dry gel, then calcining it at high temperature to obtain glass powder, and finally crystallizing it. This provides a novel high-performance basic material solution for fields such as electronics, aerospace, and high-end decoration. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the preparation process of NBAS microcrystalline glass powder.

[0026] Figure 2 This is a schematic diagram of the preparation process of NBAS glass powder.

[0027] Figure 3 The images show the XRD patterns of NBAS glass powders prepared by different heat treatment processes in Example 1.

[0028] Figure 4 The image shows the FT-IR test results of NBAS glass powder prepared by different heat treatment processes in Example 1.

[0029] Figure 5 The figure shows the bending strength test results of the NBAS glass block in Example 2.

[0030] Figure 6 The graph shows the dielectric constant and dielectric loss results of the NBAS glass block in Example 2.

[0031] Figure 7 The image shows the XRD patterns of the NBAS microcrystalline glass powders prepared in Examples 5 and 6. Detailed Implementation

[0032] This invention provides NBAS microcrystalline glass powder, NBAS glass powder, and a preparation method thereof. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention.

[0033] 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 invention pertains. The terminology used herein in the description of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0034] This invention provides a method for preparing NBAS microcrystalline glass powder, wherein, as shown in the embodiments of the present invention... Figure 1 As shown, it includes the following steps: S11. Provide a first sol, the raw materials of the first sol include the following components in parts by weight: 3-46.5 parts of sodium bicarbonate, 20-40 parts of boric acid, 30-119 parts of tetraethyl orthosilicate, 8-43 parts of aluminum nitrate nonahydrate, 0-47 parts of zinc nitrate dihydrate, and 0-10 parts of nucleating agent, wherein the nucleating agent is not 0 parts. S12. After drying the first sol, a first dry gel is obtained; S13. The first dry gel is heated to 700-900℃ (e.g., 700℃, 750℃, 800℃, 850℃, or 900℃) at a heating rate of 3-5℃ / min (e.g., 3℃ / min, 4℃ / min, or 5℃ / min) and held at that temperature for 0.5-2 h (e.g., 0.5 h, 1 h, 1.5 h, or 2 h). After natural cooling, the NBAS microcrystalline glass block is obtained. S14. The NBAS microcrystalline glass block is crushed and ball-milled to obtain NBAS microcrystalline glass powder.

[0035] The embodiments of the present invention employ a sol-gel method combined with an integrated heat treatment strategy to prepare NBAS microcrystalline glass and NBAS glass, the detailed advantages of which are described above.

[0036] In this embodiment of the invention, gelation is achieved during the drying process of the first sol to form a wet gel, and the first dry gel is formed as drying continues. Then, under a controlled heating program (heating to 700-900 °C at a rate of 3-5 °C / min and holding for 0.5-2 h), the first dry gel undergoes two sequential and natural transitions: "decomposition and expulsion of organic and inorganic matter" and "condensation and densification of amorphous networks at low temperatures." Nucleation and recrystallization then occur during natural cooling. That is, this invention creates a "melting window" with optimal viscosity and flowability for the amorphous NBAS precursor before large-scale crystal nucleation. Subsequently, guided by uniformly distributed nucleation sites (provided by a nucleating agent), the target crystalline phase precipitates uniformly from the already dense glass matrix under the action of the nucleating agent (i.e., "recrystallization").

[0037] The preparation method provided by this invention employs a low melting temperature and low energy consumption, and can ensure uniform composition of NBAS microcrystalline glass powder. Furthermore, the preparation of NBAS microcrystalline glass powder can be achieved through a single low-temperature melting and recrystallization process, making the steps simple. The prepared NBAS microcrystalline glass powder exhibits a low coefficient of thermal expansion, high flexural strength, and low dielectric constant and dielectric loss, making it applicable to fields such as ceramic binders, melting aids, composite material matrices, low-temperature co-fired ceramics, and electronic packaging ceramics.

[0038] In this embodiment, sodium bicarbonate, aluminum nitrate, boric acid, and tetraethyl orthosilicate constitute the basic components of NBAS glass-ceramics. Boric acid, as a boron source, can also regulate the melting temperature and coefficient of thermal expansion of the glass-ceramics. Zinc acetate, as a zinc source, regulates the melting temperature of the glass-ceramics. Tetrabutyl titanate and zirconium acetate act as nucleating agents for the glass-ceramics, regulating the crystallization composition and rate. Therefore, by using the above-mentioned proportions of raw materials and the specific preparation method, this invention can achieve a lower melting temperature for the prepared NBAS glass-ceramics, while also resulting in a lower coefficient of thermal expansion, lower dielectric constant and dielectric loss, and higher flexural strength.

[0039] In some embodiments, the preparation method of the first sol, by weight, includes the following steps: S111. Sodium bicarbonate, glacial acetic acid, zinc acetate dihydrate, boric acid, aluminum nitrate nonahydrate, and water are mixed to obtain solution A.

[0040] Specifically, 3-46.5 parts of sodium bicarbonate, 6-25 parts of glacial acetic acid, 0-47 parts of zinc acetate dihydrate, 20-40 parts of boric acid, 8-43 parts of aluminum nitrate nonahydrate, and 230-500 parts of water are mixed to obtain solution A.

[0041] S112. Tetraethyl orthosilicate is added to a mixed solution consisting of anhydrous ethanol, concentrated nitric acid and water. After stirring, solution B is obtained.

[0042] Specifically, 30-119 parts of tetraethyl orthosilicate are added to a mixed solution consisting of 30-90 parts of anhydrous ethanol, 0.5-1.5 parts of concentrated nitric acid, and 30-90 parts of water. After stirring, solution B is obtained. The concentrated nitric acid used in this invention has a HNO3 mass fraction of 68%.

[0043] S113. After preparing the nucleating agent into a solution, liquid C is obtained; Specifically, 0-10 parts of an aqueous solution of zirconium acetate are used as solution C; Alternatively, 0-10 parts of tetrabutyl titanate can be added to a mixed solution consisting of 5 parts anhydrous ethanol, 0.5 parts concentrated nitric acid, and 15 parts water, and stirred for 1-2 hours to obtain solution C.

[0044] S114. Add liquid B to liquid A, then add liquid C, stir, and obtain the first sol.

[0045] In step 12, in some embodiments, the first sol is dried at a temperature of 100~200℃ (e.g., 100℃, 120℃, 150℃, 180℃ or 200℃, etc.) to obtain the first dry gel.

[0046] This invention also provides an NBAS microcrystalline glass powder, which is prepared using the preparation method described above.

[0047] In this embodiment, the provided NBAS microcrystalline glass powder has a low coefficient of thermal expansion, high flexural strength, and low dielectric constant and dielectric loss, and can be applied to ceramic binders, melting aids, composite matrix, low-temperature co-fired ceramics, electronic packaging ceramics and other fields.

[0048] In some embodiments, the chemical composition of the NBAS microcrystalline glass powder includes Na2O, B2O3, SiO2, Al2O3, ZnO and a nucleating agent, wherein the nucleating agent is TiO2 and / or ZrO2. The mass ratio of Na2O, B2O3, SiO2, Al2O3, ZnO to the nucleating agent is (5~15):(30~50):(30~40):(5~10):(0~15):(0~5), and the nucleating agent component is not 0.

[0049] Among them, B2O3 can regulate the melting temperature and thermal expansion coefficient of NBAS glass-ceramics, ZnO can regulate the melting temperature and dielectric properties of glass-ceramics, and TiO2 and / or ZrO2 are nucleating agents that regulate the glass crystallization rate and have an opacifying effect.

[0050] This invention provides a method for preparing NBAS glass powder, wherein, as shown in the embodiments, Figure 2 As shown, it includes the following steps: S21. Provide a second sol, wherein the raw materials of the second sol include the following components in parts by weight: 3-46.5 parts of sodium bicarbonate, 20-40 parts of boric acid, 30-119 parts of tetraethyl orthosilicate, 8-43 parts of aluminum nitrate nonahydrate, and 0-47 parts of zinc nitrate dihydrate. S22. After drying the second sol, a second dry gel is obtained; S23. The second dry gel is heated to 700-900℃ (e.g., 700℃, 750℃, 800℃, 850℃, or 900℃) at a heating rate of 3-5℃ / min (e.g., 3℃ / min, 4℃ / min, or 5℃ / min) and held at that temperature for 0.5-2 h (e.g., 0.5 h, 1 h, 1.5 h, or 2 h). After natural cooling, an NBAS glass block is obtained. S24. The NBAS glass block is crushed and ball-milled to obtain NBAS glass powder.

[0051] In this embodiment of the invention, no nucleating agent is added, and the resulting product is NBAS glass powder. The preparation method provided by this invention utilizes a low melting temperature, consumes less energy, and ensures uniform composition of the NBAS glass powder. Furthermore, the preparation of NBAS glass powder can be achieved through a single low-temperature melting process, simplifying the steps. The prepared NBAS glass powder exhibits a low coefficient of thermal expansion, high flexural strength, and low dielectric constant and dielectric loss, making it suitable for applications in ceramic binders, melting aids, composite material matrices, low-temperature co-fired ceramics, and electronic packaging ceramics.

[0052] In step S21, in some embodiments, the preparation method of the second sol includes the following steps: Sodium bicarbonate, glacial acetic acid, zinc acetate dihydrate, boric acid, aluminum nitrate nonahydrate, and water are mixed to obtain solution A. Tetraethyl orthosilicate was added to a mixed solution consisting of anhydrous ethanol, concentrated nitric acid, and water. After stirring, solution B was obtained. The B solution is added to the A solution, and after stirring, a second sol is obtained.

[0053] In step S23, in some embodiments, the second sol is dried at a temperature of 100~200℃ (e.g., 100℃, 120℃, 150℃, 180℃ or 200℃, etc.) to obtain a second dry gel.

[0054] This invention also provides an NBAS glass powder, which is prepared using the preparation method described above.

[0055] In some embodiments, the chemical composition of the NBAS glass powder includes Na2O, B2O3, SiO2, Al2O3 and ZnO, wherein the mass ratio of Na2O, B2O3, SiO2, Al2O3 and ZnO is (5~15):(30~50):(30~40):(5~10):(0~5).

[0056] The NBAS glass powder provided in this embodiment has a low coefficient of thermal expansion, high flexural strength, and low dielectric constant and dielectric loss, and can be applied to ceramic binders, melting aids, composite matrix, low-temperature co-fired ceramics, electronic packaging ceramics and other fields.

[0057] The present invention will be further described below through specific embodiments.

[0058] Unless otherwise specified, the raw materials used in the following embodiments are all commercially available products.

[0059] Example 1 This embodiment provides a method for preparing NBAS glass powder, which includes the following steps by weight: Mix 11.01 parts sodium bicarbonate, 6 parts glacial acetic acid and 100 parts water until completely dissolved, then add 6.13 parts zinc acetate dihydrate, 40 parts boric acid, 19.92 parts aluminum nitrate nonahydrate and 200 parts water. Stir magnetically for 1 hour until completely clear to obtain solution A. 47 parts of tetraethyl orthosilicate were gradually added to a mixed solution consisting of 30 parts of anhydrous ethanol, 0.5 parts of concentrated nitric acid and 30 parts of deionized water, and the mixture was magnetically stirred for 0.5 h (to complete hydrolysis) to obtain solution B. Then add the above solution B to the above solution A and mix quickly, then stir magnetically for 5 minutes to obtain a sol; The above sol was dried at 150 °C for 12 h to obtain a dry gel; The dried gel was subjected to the following five heat treatment processes and then naturally cooled to room temperature to obtain five transparent NBAS glass blocks; Five types of NBAS glass blocks were crushed and ball-milled to obtain five types of NBAS glass powders.

[0060] The five heat treatment processes are as follows: (1) Heat to 700 ℃ at a heating rate of 5 ℃ / min and hold for 1 h; (2) Heat to 900 ℃ at a heating rate of 5 ℃ / min and hold for 1 h; (3) Heat to 1100 ℃ at a heating rate of 5 ℃ / min and hold for 1 h; (4) Heat to 700 ℃ at a heating rate of 5 ℃ / min and hold for 1 h, then heat to 1000 ℃ at a heating rate of 5 ℃ / min and hold for 1 h. (5) Heat to 900 ℃ at a heating rate of 5 ℃ / min and hold for 1 h, then heat to 1000 ℃ at a heating rate of 5 ℃ / min and hold for 1 h.

[0061] X-ray diffraction (XRD) patterns of five types of NBAS glass powders are shown below. Figure 3 As shown, the XRD patterns of NBAS glass powder obtained under different heat treatment conditions all show broadened, dome-shaped diffraction peaks, which are typical amorphous glassy states. Moreover, even after multiple heat treatments, the amorphous structure is still maintained.

[0062] The FT-IR (Fourier Transform Infrared) test results of NBAS glass powder prepared under different heat treatment conditions are as follows: Figure 4 As shown, 120 °C for 1 h represents the dry gel prepared during the process. It can be seen that after heating the dry gel to 700 °C and higher, the absorption peaks remain essentially the same, with only slight shifts in intensity and position, indicating that the glass matrix structure does not change significantly after heat treatment. After further heat treatment, the amorphous network structure of the glass matrix is ​​still preserved, further validating the XRD analysis results. This also shows that adding excessive B2O3 still cannot form a glass-ceramic structure.

[0063] Example 2 This embodiment provides a method for preparing NBAS glass powder, which includes the following steps by weight: Mix 11.01 parts sodium bicarbonate, 6 parts glacial acetic acid and 100 parts water until completely dissolved, then add 6.13 parts zinc acetate dihydrate, 40 parts boric acid, 19.92 parts aluminum nitrate nonahydrate and 200 parts water. Stir magnetically for 1 hour until completely clear to obtain solution A. 47 parts of tetraethyl orthosilicate were gradually added to a mixed solution consisting of 30 parts of anhydrous ethanol, 0.5 parts of concentrated nitric acid and 30 parts of deionized water, and the mixture was magnetically stirred for 0.5 h (to complete hydrolysis) to obtain solution B. Then add the above solution B to the above solution A and mix quickly, then stir magnetically for 5 minutes to obtain a sol; The above sol was dried at 150 °C for 12 h, then heated to 820 °C at a heating rate of 5 °C / min and held for 1 h (to completely melt). After naturally cooling to room temperature, a transparent NBAS glass block was obtained. NBAS glass blocks are crushed and ball-milled to obtain NBAS glass powder with a particle size D50 of 10 μm. The chemical composition of the obtained NBAS glass powder consists of Na2O, ZnO, B2O3, SiO2 and Al2O3 in a mass ratio of 9:5:50:30:6 (which can be written as 9Na2O-5ZnO-50B2O3-30SiO2-6Al2O3).

[0064] The density of the NBAS glass block prepared in this embodiment was tested to be 2.22 g / cm³. 3 The coefficient of thermal expansion is 5.3 × 10⁻⁶. -6 / K, flexural strength is 64.9 MPa (see Figure 5 The elastic modulus is 39.74 GPa, and the average dielectric constant of the X-band (8.2~12.4 GHz) measured using the waveguide method is 5.09, with a dielectric loss of 0.01 (see...). Figure 6 It has a small dielectric constant and dielectric loss, and the dielectric constant and dielectric loss change little with frequency.

[0065] Example 3 This embodiment provides a method for preparing NBAS glass powder, which includes the following steps by weight: Mix 3 parts sodium bicarbonate, 6 parts glacial acetic acid and 100 parts water until completely dissolved, then add 21 parts boric acid, 8.15 parts aluminum nitrate nonahydrate and 130 parts water. Stir magnetically for 1 hour until completely clear to obtain solution A. 30 parts of tetraethyl orthosilicate were gradually added to a mixed solution consisting of 30 parts of anhydrous ethanol, 0.5 parts of concentrated nitric acid and 30 parts of deionized water, and the mixture was magnetically stirred for 0.5 h (to complete hydrolysis) to obtain solution B. Then, add the above solution B to the above solution A and mix quickly, then stir magnetically for 5 minutes to obtain a sol; The above sol was dried at 150 °C for 10 h, then heated to 850 °C at a heating rate of 5 °C / min and held for 2 h (to completely melt). After naturally cooling to room temperature, a transparent NBAS glass block was obtained. NBAS glass blocks are crushed and ball-milled to obtain NBAS glass powder. The chemical composition of the obtained NBAS glass powder consists of Na2O, B2O3, SiO2 and Al2O3 in a mass ratio of 5:50:40:5 (which can be written as 5Na2O-50B2O3-40SiO2-5Al2O3).

[0066] According to testing, the density of the NBAS glass block in this embodiment is 2.4 g / cm³. 3 The coefficient of thermal expansion is 4.6 × 10⁻⁶. -6 The flexural strength is 75 MPa, and the average dielectric constant of the X-band (8.2~12.4 GHz) tested by the waveguide method is 4.3, and the dielectric loss is 0.001.

[0067] Example 4 This embodiment provides a method for preparing NBAS glass powder, which includes the following steps by weight: Mix 46.5 parts sodium bicarbonate, 25 parts glacial acetic acid and 200 parts water until completely dissolved, then add 46.6 parts zinc acetate dihydrate, 40 parts boric acid, 42.1 parts aluminum nitrate nonahydrate and 300 parts water. Stir magnetically for 1 hour until completely clear to obtain solution A. 119 parts of tetraethyl orthosilicate were gradually added to a mixed solution consisting of 90 parts of anhydrous ethanol, 1.5 parts of concentrated nitric acid and 90 parts of deionized water and stirred magnetically for 0.5 h (to complete hydrolysis) to obtain solution B. Then add the above solution B to the above solution A and mix quickly, then stir magnetically for 5 minutes to obtain a sol; The above sol was dried at 200 °C for 15 h, then heated to 800 °C at a heating rate of 5 °C / min and held for 1 h (to completely melt). After naturally cooling to room temperature, a transparent NBAS glass block was obtained. NBAS glass blocks were crushed and ball-milled to obtain NBAS glass powder. The chemical composition of the obtained NBAS glass powder consisted of Na2O, ZnO, B2O3, SiO2, and Al2O3 in a mass ratio of 15:15:35:30:5 (which can be written as 15Na2O-15ZnO-35B2O3-30SiO2-5Al2O3).

[0068] The density of the NBAS glass block was tested to be 2.3 g / cm³. 3 The coefficient of thermal expansion is 6.7 × 10⁻⁶. -6 The flexural strength is 65 MPa, and the average dielectric constant of the X-band (8.2~12.4 GHz) tested by the waveguide method is 5.4, and the dielectric loss is 0.01.

[0069] Example 5 This embodiment provides a method for preparing NBAS microcrystalline glass powder, which includes the following steps by weight: Mix 11.01 parts sodium bicarbonate, 6 parts glacial acetic acid and 100 parts water until completely dissolved, then add 6.13 parts zinc acetate dihydrate, 36 parts boric acid, 19.92 parts aluminum nitrate nonahydrate and 200 parts water. Stir magnetically for 1 hour until completely clear to obtain solution A. 47 parts of tetraethyl orthosilicate were gradually added to a mixed solution consisting of 30 parts of anhydrous ethanol, 0.5 parts of concentrated nitric acid and 30 parts of deionized water, and the mixture was magnetically stirred for 0.5 h (to complete hydrolysis) to obtain solution B. A mixed solution of 5 parts tetrabutyl titanate and 10 parts anhydrous ethanol was gradually added to a mixed solution of 5 parts anhydrous ethanol, 0.5 parts concentrated nitric acid and 15 parts deionized water, and the mixture was magnetically stirred for 1.5 h (to complete hydrolysis) to obtain solution C. Add the above solution B to solution A, then add solution C and mix quickly. Stir magnetically for 5 minutes to obtain a sol. The above sol was dried at 150 °C for 12 h, and then heated to 820 °C at a heating rate of 5 °C / min and held for 1 h (to completely melt). After naturally cooling to room temperature, a white NBAS microcrystalline glass block was obtained.

[0070] NBAS microcrystalline glass blocks were crushed and ball-milled to obtain microcrystalline NBAS glass powder. The chemical composition of the obtained microcrystalline NBAS glass powder consisted of Na2O, ZnO, B2O3, SiO2, Al2O3, and TiO2 in a mass ratio of 9:5:45:30:6:5 (which can be written as 9Na2O-5ZnO-45B2O3-30SiO2-6Al2O3-5TiO2).

[0071] XRD analysis revealed that the main microcrystalline phase of the NBAS glass-ceramic powder was nepheline, while the matrix was an amorphous glass (see [link]). Figure 7 TiO2 acts as a nucleating agent; when added to the sol, it can form glass-ceramics at low temperatures. Compared to the melting method, this significantly reduces the formation temperature of glass-ceramics. Compared to the traditional sol-gel method, only one heat treatment process is needed to achieve recrystallization.

[0072] The density of the NBAS microcrystalline glass block was tested to be 2.5 g / cm³. 3 The coefficient of thermal expansion is 4.4 × 10⁻⁶. -6 The flexural strength is 70 MPa, and the average dielectric constant of the X-band (8.2~12.4 GHz) tested by the waveguide method is 5.2, and the dielectric loss is 0.001.

[0073] Example 6 This embodiment provides a method for preparing NBAS microcrystalline glass powder, which includes the following steps by weight: Mix 46.5 parts sodium bicarbonate, 25 parts glacial acetic acid and 200 parts water until completely dissolved, then add 46.6 parts zinc acetate dihydrate, 34.3 parts boric acid, 42.1 parts aluminum nitrate nonahydrate and 300 parts water, stir magnetically for 1 h until completely clear, to obtain solution A; 119 parts of tetraethyl orthosilicate were gradually added to a mixed solution consisting of 90 parts of anhydrous ethanol, 1.5 parts of concentrated nitric acid and 90 parts of deionized water, and the mixture was magnetically stirred for 0.5 h (to complete hydrolysis) to obtain solution B. Ten parts of an aqueous solution of zirconium acetate (with a zirconium acetate mass fraction of 16%) were used as solution C; Add the above solution B to solution A, then add solution C and mix quickly. Stir magnetically for 5 minutes to obtain a sol. The above sol was dried at 200 °C for 10 h, and then heated to 820 °C at a heating rate of 5 °C / min and held for 0.5 h (to completely melt). After natural cooling, a white NBAS microcrystalline glass block was obtained. NBAS microcrystalline glass blocks were crushed and ball-milled to obtain NBAS microcrystalline glass powder. The chemical composition of the obtained NBAS microcrystalline glass powder consisted of Na2O, ZnO, B2O3, SiO2, Al2O3, and ZrO2 in a mass ratio of 15:15:30:30:5:5 (which can be written as 15Na2O-15ZnO-30B2O3-30SiO2-5Al2O3-5ZrO2).

[0074] ZrO2, acting as a nucleating agent, has a similar effect to TiO2. XRD analysis shows that the microcrystalline phase of the NBAS glass-ceramic powder is mainly nepheline phase, and the matrix is ​​an amorphous glass (see...). Figure 7 ).

[0075] According to testing, the density of the NBAS microcrystalline glass block in this embodiment is 2.45 g / cm³. 3 The coefficient of thermal expansion is 4.8 × 10⁻⁶. -6 The flexural strength is 68 MPa, and the average dielectric constant of the X-band (8.2~12.4 GHz) tested by the waveguide method is 5.64, and the dielectric loss is 0.001.

[0076] In summary, this invention provides NBAS microcrystalline glass powder, NBAS glass powder, and a preparation method thereof. This invention employs a sol-gel method combined with an integrated heat treatment strategy to prepare NBAS microcrystalline glass and NBAS glass, offering the following advantages: (1) It possesses molecular-level uniformity and a low melting temperature. Specifically, this invention uses tetraethyl orthosilicate, boric acid, sodium bicarbonate, aluminum nitrate, etc., in specific proportions as raw materials to form a three-dimensional network gel through hydrolysis-condensation reaction, ensuring that elements such as Na, B, Al, and Si achieve uniform distribution at the molecular / atomic scale. This extreme uniformity fundamentally eliminates the component segregation caused by phase separation or volatilization in existing high-temperature melting methods, laying the foundation for obtaining materials with highly reproducible properties. Because the composition is uniform and the content of B2O3 and Na2O is precisely controlled, the softening point of the glass phase is significantly reduced. Therefore, the decomposition of the precursor and the formation and densification of the glass network can be completed at a temperature of only a few hundred degrees Celsius (700~900 ℃), avoiding the high-energy-consuming melting process above 1400 ℃ in traditional processes, significantly reducing energy consumption and production costs, and completely solving the problem of high-temperature volatilization of B2O3 and Na2O, making it possible to accurately realize low-melting-point formulations.

[0077] (2) Integrated heat treatment enables precise control of structural properties. This invention abandons the traditional two-step method of "preparing glass powder first, then external crystallization" and innovatively performs integrated heat treatment on the dry gel. In this process, the decomposition and removal of inorganic and organic matter, the formation and densification of the inorganic glass network, the induction effect of the nucleating agent, and the precipitation and growth of the target crystal phase are integrated into a continuous and controllable thermal program, and the steps are simple. Specifically, by utilizing the high activity and uniform composition of sol and gel, and through precise control of the heat treatment regime, the glass matrix is ​​first fully densified at a relatively low temperature (the lower temperature in the programmed heating process). Then, during the cooling process, uniform and numerous nuclei are induced in the nucleating agent enrichment area, and the uniformly distributed nucleating agent (TiO2 / ZrO2) can effectively reduce the crystallization activation energy and promote the uniform precipitation of subsequent nanocrystals. This "densification first, then internal growth" approach allows for the preferential precipitation of Al- and Si-rich crystalline phases with low expansion characteristics (such as nepheline solid solution or similar structures), while confining elements like B and Na within the residual glassy phase to maintain low melting points. This cleverly resolves the traditional contradiction between "low expansion" and "low melting point." In other words, by inducing the precipitation of a large number of low-expansion crystalline phases and controlling their nanoscale and uniform distribution, the material can achieve a low overall coefficient of thermal expansion, ensuring good compatibility with semiconductor chips. Furthermore, the highly dense microstructure, pure crystalline phases, and controlled residual glassy phase collectively endow the material with excellent high-frequency dielectric properties.

[0078] (3) Controllable achievement of opacification effect and white appearance. In this invention, a specific amount of TiO2 and / or ZrO2 is incorporated into the composition of NBAS glass as nucleating agents. In the highly uniform precursor prepared by the sol-gel method, these nucleating agents are uniformly dispersed in the form of ions or nanoclusters. During the integrated heat treatment process, they first induce uniform, high-density liquid-liquid phase separation or directly form primary crystal phases (such as ZrTiO4), and then the main crystal phase (such as crystal phases containing Al and Si) precipitates, ultimately forming numerous crystal-glass phase interfaces with sizes comparable to the wavelength of visible light within the material. Light undergoes a strong scattering effect at these interfaces, thereby producing an excellent opacification effect. More importantly, due to the high purity and uniformity of the starting materials in this invention, and the fact that this invention avoids the high-temperature reducing atmosphere and long-term heat treatment of the traditional melting method, Ti ions in this invention can be stably maintained in a high valence state (Ti 4+ This effectively suppressed the effects of Ti. 3+ The presence of substances such as yellowish-brown ensures that the final microcrystalline glass powder presents a pure white color.

[0079] Therefore, this invention organically combines the sol-gel method with an integrated heat treatment process, employing a low melting temperature and low energy consumption. It also ensures uniform composition of the NBAS microcrystalline glass powder. Furthermore, the preparation of NBAS microcrystalline glass powder can be achieved through a single low-temperature melting and recrystallization process, simplifying the steps. The resulting NBAS microcrystalline glass powder exhibits a low coefficient of thermal expansion, high flexural strength, and low dielectric constant and dielectric loss. This invention effectively solves the problems of poor component uniformity, volatilization of key components, high melting temperature, and high energy consumption inherent in existing high-temperature melting-quenching-mechanical pulverization methods for preparing NBAS powder. It also addresses the cumbersome process of existing sol-gel methods, which require first preparing a dry gel, then calcining it at high temperature to obtain glass powder, and finally crystallizing it. This provides a novel high-performance basic material solution for fields such as electronics, aerospace, and high-end decoration.

[0080] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for preparing NBAS microcrystalline glass powder, characterized in that, Includes the following steps: A first sol is provided, the raw materials of which include the following components in parts by weight: 3-46.5 parts of sodium bicarbonate, 20-40 parts of boric acid, 30-119 parts of tetraethyl orthosilicate, 8-43 parts of aluminum nitrate nonahydrate, 0-47 parts of zinc nitrate dihydrate, and 0-10 parts of nucleating agent, wherein the nucleating agent is not 0 parts. After drying the first sol, a first dry gel is obtained; The first dry gel was heated to 700-900 ℃ at a heating rate of 3-5 ℃ / min and held at that temperature for 0.5-2 h. After natural cooling, NBAS microcrystalline glass block was obtained. The NBAS microcrystalline glass block is crushed and ball-milled to obtain NBAS microcrystalline glass powder.

2. The preparation method according to claim 1, characterized in that, The preparation method of the first sol includes the following steps: Sodium bicarbonate, glacial acetic acid, zinc acetate dihydrate, boric acid, aluminum nitrate nonahydrate, and water are mixed to obtain solution A. Tetraethyl orthosilicate was added to a mixed solution consisting of anhydrous ethanol, concentrated nitric acid, and water. After stirring, solution B was obtained. The nucleating agent was added to a mixed solution consisting of anhydrous ethanol, concentrated nitric acid, and water, and after stirring, solution C was obtained. Liquid B is added to liquid A, then liquid C is added, and after stirring, the first sol is obtained.

3. The preparation method according to claim 1, characterized in that, The nucleating agent comprises tetrabutyl titanate and / or an aqueous solution of zirconium acetate; The first sol was dried at a temperature of 100~200 °C to obtain the first dry gel.

4. An NBAS microcrystalline glass powder, characterized in that, It is prepared by the preparation method according to any one of claims 1-3.

5. The NBAS microcrystalline glass powder according to claim 4, characterized in that, The chemical composition of the NBAS microcrystalline glass powder includes Na2O, B2O3, SiO2, Al2O3, ZnO and a nucleating agent, wherein the nucleating agent is TiO2 and / or ZrO2. The mass ratio of Na2O, B2O3, SiO2, Al2O3, ZnO to the nucleating agent is (5~15):(30~50):(30~40):(5~10):(0~15):(0~5), and the nucleating agent component is not 0.

6. A method for preparing NBAS glass powder, characterized in that, Includes the following steps: A second sol is provided, the raw materials of which include the following components in parts by weight: 3-46.5 parts sodium bicarbonate, 20-40 parts boric acid, 30-119 parts tetraethyl orthosilicate, 8-43 parts aluminum nitrate nonahydrate, and 0-47 parts zinc nitrate dihydrate; After drying the second sol, a second dry gel is obtained; The second dry gel was heated to 700-900 ℃ at a heating rate of 3-5 ℃ / min and held at that temperature for 0.5-2 h. After natural cooling, NBAS glass blocks were obtained. The NBAS glass block is crushed and ball-milled to obtain NBAS glass powder.

7. The preparation method according to claim 6, characterized in that, The second sol was dried at a temperature of 100~200 °C to obtain the second dry gel.

8. The preparation method according to claim 6, characterized in that, The preparation method of the second sol includes the following steps: Sodium bicarbonate, glacial acetic acid, zinc acetate dihydrate, boric acid, aluminum nitrate nonahydrate, and water are mixed to obtain solution A. Tetraethyl orthosilicate was added to a mixed solution consisting of anhydrous ethanol, concentrated nitric acid, and water. After stirring, solution B was obtained. The B solution is added to the A solution, and after stirring, a second sol is obtained.

9. An NBAS glass powder, characterized in that, It is prepared by the preparation method according to any one of claims 6-8.

10. The NBAS glass powder according to claim 9, characterized in that, The chemical composition of the NBAS glass powder includes Na2O, B2O3, SiO2, Al2O3 and ZnO, wherein the mass ratio of Na2O, B2O3, SiO2, Al2O3 and ZnO is (5~15):(30~50):(30~40):(5~10):(0~5).

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