A barium titanate high-pressure ceramic material and its solid-state sintering preparation method and application

Abstract

This invention relates to a barium titanate high-pressure ceramic material, its solid-state sintering preparation method, and its application. The solid-state sintering preparation method includes: mixing barium titanate powder and auxiliary powder, and then sintering the resulting mixed powder to obtain the barium titanate high-pressure ceramic material. The auxiliary powder comprises strontium carbonate and titanium dioxide in a molar ratio of 0.8:1 to 1.2:1; the molar ratio of barium titanate powder to auxiliary powder is 5:1 to 10:1. This invention improves the dielectric properties and high-voltage resistance of barium titanate ceramics under high-voltage environments using only simple auxiliary materials. Moreover, the solid-state sintering preparation method provided by this invention is simple and easy to implement, enabling the industrial-scale production of barium titanate high-pressure ceramic materials.

Description

Technical Field

[0001] This invention belongs to the field of ceramic capacitor technology, and relates to a high-voltage ceramic material, particularly a barium titanate high-voltage ceramic material and its solid-state sintering preparation method and application. Background Technology

[0002] High-voltage ceramic capacitors are widely used in focusing circuits, high-voltage power supply circuits, and pulse energy processing equipment, requiring high withstand voltage, high dielectric constant, low loss, high energy storage, and high stability. Barium titanate has a high dielectric constant, enabling it to store maximum electrical energy in a very small volume, thus it is widely used as the core dielectric material for energy storage capacitors. However, unmodified barium titanate ceramics have significant drawbacks: their dielectric properties are highly sensitive to DC bias and temperature changes, their dielectric constant changes rapidly, and their breakdown field strength is low, making it difficult to meet the reliability requirements of high-voltage capacitors. Therefore, barium titanate ceramics must be modified to make them suitable for high-voltage ceramic capacitors.

[0003] Most existing technologies employ liquid-phase synthesis for the industrial production of modified barium titanate ceramic materials. However, liquid-phase synthesis involves high raw material costs, complex processing techniques, and requires high pressures and temperatures, resulting in high investment and construction costs. Furthermore, the hydrothermal synthesis process generates large amounts of wastewater, causing severe environmental pollution. Solid-phase sintering, compared to liquid-phase synthesis, offers higher sintering efficiency, abundant raw material sources, lower initial investment, simpler processes, higher automation, and lower labor intensity, making it easier to achieve industrial-scale production. However, there is currently no industrial-scale method for producing barium titanate high-pressure ceramic materials.

[0004] Therefore, how to improve the solid-state sintering process and use it for large-scale industrial production of barium titanate high-pressure ceramic materials is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a barium titanate high-pressure ceramic material, its solid-state sintering preparation method, and its application. The solid-state sintering preparation method enables the barium titanate high-pressure ceramic material to exhibit good dielectric properties and high-voltage resistance under high-voltage environments; it also facilitates industrial-scale production.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a solid-state sintering preparation method for barium titanate high-pressure ceramic materials, the solid-state sintering preparation method comprising:

[0008] Barium titanate powder and auxiliary powder are mixed, and the resulting mixed powder is sintered to obtain the barium titanate high-pressure ceramic material.

[0009] The auxiliary powder comprises strontium carbonate and titanium dioxide in a molar ratio of 0.8:1 to 1.2:1;

[0010] The molar ratio of barium titanate powder to auxiliary powder is 5:1-10:1.

[0011] The solid-state sintering preparation method provided by this invention can improve the dielectric properties and high-voltage resistance of barium titanate ceramics under high-voltage environments by using only simple auxiliary materials; moreover, the solid-state sintering preparation method provided by this invention is simple and easy to implement, and can realize the industrial-scale production of barium titanate high-voltage ceramic materials.

[0012] Preferably, the heating rate of the sintering process is 2℃ / min-10℃ / min.

[0013] Preferably, the maximum temperature of the sintering treatment is 1200℃-1480℃.

[0014] Preferably, the holding time at the highest temperature during the sintering process is 0.5h-3h.

[0015] Preferably, the barium titanate powder is prepared by the following solid-state sintering method: mixing barium source and titanium source to obtain raw material powder; then pre-firing the raw material powder to obtain pre-firing blank; the pre-firing blank is subjected to a first crushing treatment, grinding, carbon removal treatment and a second crushing treatment in sequence to obtain the barium titanate powder.

[0016] Preferably, the barium source includes barium carbonate and / or barium oxide.

[0017] Preferably, the titanium source includes titanium dioxide.

[0018] Preferably, the molar ratio of Ba in the barium source to Ti in the titanium source is 0.990:1-1.010:1.

[0019] Preferably, the median particle size D50 of the raw material powder is 0.8μm-3.5μm.

[0020] Preferably, the preheating rate is 5°C / min to 10°C / min.

[0021] Preferably, the maximum pre-firing temperature is 1150℃-1350℃.

[0022] Preferably, the preheating time at the highest temperature is 30 min to 180 min.

[0023] Preferably, the first crushing process includes depolymerization.

[0024] Preferably, the median particle size D50 of the powder after the first crushing treatment is 0.8μm-3.5μm.

[0025] Preferably, the grinding method includes sand milling; the median particle size D50 of the powder obtained by sand milling is 0.6μm-1.5μm.

[0026] Preferably, the carbon removal treatment includes: removing carbon at 450℃-800℃ for 8h-18h.

[0027] Preferably, the carbon removal process further includes drying before carbon removal: drying at a temperature of 80℃-180℃ for 6h-18h.

[0028] Preferably, the auxiliary powder is prepared by the following solid-state sintering method: strontium carbonate and titanium dioxide are mixed according to the formula, the mixed powder is dried and decarbonized, and then subjected to a third crushing process to obtain the auxiliary powder.

[0029] Preferably, the drying temperature is 80℃-180℃ and the drying time is 6h-18h.

[0030] Preferably, the carbon removal temperature is 450℃-800℃ and the time is 8h-18h.

[0031] In a second aspect, the present invention provides a barium titanate high-pressure ceramic material, which is prepared by the solid-state sintering preparation method described in the first aspect.

[0032] Thirdly, the present invention provides a high-voltage capacitor, the high-voltage capacitor comprising barium titanate high-voltage ceramic material prepared by the solid-state sintering preparation method described in the first aspect, or comprising barium titanate high-voltage ceramic material described in the second aspect.

[0033] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The solid-state sintering preparation method provided by this invention can improve the dielectric properties and high-voltage resistance of barium titanate ceramics under high-voltage environments by using only simple auxiliary materials; moreover, the solid-state sintering preparation method provided by this invention is simple and easy to implement, and can realize the industrial-scale production of barium titanate high-voltage ceramic materials. Detailed Implementation

[0036] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0037] An embodiment of the present invention provides a solid-state sintering preparation method for barium titanate high-pressure ceramic materials, the solid-state sintering preparation method comprising:

[0038] Barium titanate powder and auxiliary powder are mixed, and the resulting mixed powder is sintered to obtain the barium titanate high-pressure ceramic material.

[0039] The auxiliary powder comprises strontium carbonate and titanium dioxide in a molar ratio of 0.8:1 to 1.2:1, for example, it can be 0.8:1, 0.9:1, 1:1, 1.1:1 or 1.2:1, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0040] The molar ratio of barium titanate powder to auxiliary powder is 5:1-10:1, for example, it can be 5:1, 6:1, 8:1, 9:1 or 10:1, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0041] The solid-state sintering preparation method provided by this invention can improve the dielectric properties and high-voltage resistance of barium titanate ceramics under high-voltage environments by using only simple auxiliary materials; moreover, the solid-state sintering preparation method provided by this invention is simple and easy to implement, and can realize the industrial-scale production of barium titanate high-voltage ceramic materials.

[0042] In some embodiments, the heating rate of the sintering process is 2℃ / min-10℃ / min, for example, it can be 2℃ / min, 4℃ / min, 5℃ / min, 6℃ / min, 8℃ / min or 10℃ / min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0043] In some embodiments, the maximum temperature of the sintering process is 1200℃-1480℃, for example, it can be 1200℃, 1250℃, 1300℃, 1350℃, 1400℃, 1450℃ or 1480℃, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0044] In some embodiments, the holding time at the highest temperature during the sintering process is 0.5h-3h, for example, it can be 0.5h, 1h, 1.5h, 2h, 2.5h or 3h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0045] In some embodiments, the barium titanate powder is prepared by the following solid-state sintering method: mixing a barium source and a titanium source to obtain a raw material powder; then pre-firing the raw material powder to obtain a pre-firing blank; the pre-firing blank is subjected to a first crushing treatment, grinding, carbon removal treatment and a second crushing treatment in sequence to obtain the barium titanate powder.

[0046] The solid-state sintering preparation method provided by this invention, by employing a specific solid-state sintering preparation method for barium titanate powder, can make the median particle size distribution of the obtained barium titanate powder more concentrated, thereby giving the barium titanate high-voltage ceramic material good high-voltage resistance and good dielectric properties under high-voltage environment (breakdown voltage above 31kV / mm, preferably above 39kV / mm).

[0047] The pre-calcination process allows the titanium and barium sources to undergo a solid-phase reaction, eliminating moisture, volatile impurities, gases, and some organic matter from the raw materials, thereby improving the purity of the prepared barium titanate powder. Furthermore, the barium titanate powder obtained from the pre-calcination process better integrates with the auxiliary powder during subsequent sintering, resulting in barium titanate high-pressure ceramic materials exhibiting excellent dielectric properties under high-pressure conditions.

[0048] In some embodiments, the barium source includes barium carbonate and / or barium oxide.

[0049] In some embodiments, the titanium source includes titanium dioxide.

[0050] In some embodiments, the molar ratio of Ba in the barium source to Ti in the titanium source is 0.990:1 to 1.010:1, for example, it can be 0.990:1, 0.995:1, 1.000:1, 1.005:1 or 1.010:1, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0051] In some embodiments, the median particle size D50 of the raw material powder is 0.8μm-3.5μm, for example, it can be 0.8μm, 1μm, 1.5μm, 2μm, 2.5μm, 3μm or 3.5μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0052] To obtain raw material powder with a median particle size D50 of 0.8μm-3.5μm, the barium source and titanium source were first mixed in a three-dimensional mixer, and then an air jet mill was used to obtain raw material powder with a median particle size D50 of 0.8μm-3.5μm.

[0053] In some embodiments, the median particle size D50 of the barium source is 3μm-15μm, for example, it can be 3μm, 5μm, 8μm, 10μm, 12μm or 15μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0054] In some embodiments, the median particle size D50 of the titanium source is 3μm-15μm, for example, it can be 3μm, 5μm, 8μm, 10μm, 12μm or 15μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0055] In some embodiments, the preheating rate is 5°C / min-10°C / min, for example, 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min or 10°C / min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0056] In this invention, the starting temperature for pre-firing is room temperature, for example, it can be 15℃-30℃, for example, it can be 15℃, 18℃, 20℃, 25℃, 28℃ or 30℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0057] In some embodiments, the maximum preheating temperature is 1150°C-1350°C, for example, it can be 1150°C, 1200°C, 1250°C, 1300°C or 1350°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0058] In some embodiments, the preheating time at the highest temperature is 30 min to 180 min, for example, it can be 30 min, 50 min, 80 min, 100 min, 120 min, 150 min, 160 min or 180 min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0059] In some embodiments, the method of the first fragmentation process includes depolymerization.

[0060] For example, depolymerization is carried out in an air jet mill.

[0061] In some embodiments, the median particle size D50 of the powder after the first crushing treatment is 0.8μm-3.5μm, for example, it can be 0.8μm, 1μm, 1.5μm, 2μm, 2.5μm, 3μm or 3.5μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0062] In some embodiments, to obtain powder with a median particle size D50 of 0.8 μm-3.5 μm by air jet milling and to reduce the operating pressure of the air jet mill, the first crushing process includes coarse crushing by jaw crusher, fine crushing by roller mill, and deagglomeration by air jet milling in sequence. The terms "coarse crushing" and "fine crushing" are relative concepts, meaning that the average median particle size of the material obtained from coarse crushing is greater than the average median particle size of the material obtained from fine crushing.

[0063] In some embodiments, the grinding method includes sand milling; the median particle size D50 of the powder obtained by sand milling is 0.6μm-1.5μm, for example, it can be 0.6μm, 0.8μm, 1μm, 1.2μm or 1.5μm, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0064] This invention does not specifically limit the grinding method, time, or other parameters. As long as the median particle size D50 of the powder obtained by grinding is 0.6μm-1.5μm, it is acceptable. Generally speaking, controlling the grinding time to 30min-180min can achieve the technical effect of the median particle size D50 of the material obtained by grinding being 0.6μm-1.5μm.

[0065] Grinding can further refine the particle size of barium titanate powder, increasing its specific surface area as the particle size decreases, which is beneficial for subsequent sintering to obtain dense barium titanate high-pressure ceramic materials. However, during the process of particle size refinement, the fine particles re-aggregate under the influence of van der Waals forces and electrostatic double-layer effects. Therefore, as a preferred technical solution, a dispersant is used during grinding to prevent the barium titanate powder from agglomerating. Consequently, a carbon removal treatment is required after grinding to remove the dispersant.

[0066] This invention does not impose specific limitations on the amount or type of dispersant, as long as the dispersion effect during grinding can be achieved.

[0067] In some embodiments, the carbon removal process includes: removing carbon at 450°C-800°C for 8-18 hours.

[0068] The carbon removal temperature is 450℃-800℃, for example, it can be 450℃, 500℃, 600℃, 700℃ or 800℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0069] The carbon removal time is 8h-18h, for example, it can be 8h, 10h, 12h, 15h, 16h or 18h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0070] In some embodiments, water is used as the grinding medium in the sand milling process. Water has a good dispersing effect. During the sand milling process, it is adsorbed on the surface of solid particles, which reduces the interfacial tension between liquid and solid and liquid, making the surface of the aggregated solid particles easier to wet and preventing the agglomeration of fine particles. However, the residual water is not conducive to the subsequent sintering.

[0071] Preferably, the carbon removal process further includes drying before carbon removal: drying at a temperature of 80℃-180℃ for 6h-18h.

[0072] The drying temperature is 80℃-180℃, for example, it can be 80℃, 100℃, 120℃, 150℃, 160℃ or 180℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0073] The drying time is 6h-18h, for example, it can be 6h, 8h, 10h, 12h, 15h, 16h or 18h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0074] In some embodiments, the auxiliary powder is prepared by the following solid-state sintering preparation method: strontium carbonate and titanium dioxide are mixed according to the formula amount, the mixed powder is dried and decarbonized, and then subjected to a third crushing treatment to obtain the auxiliary powder.

[0075] The solid-state sintering preparation method provided by this invention, by using a specific solid-state sintering preparation method on the auxiliary powder, can make the particle size distribution of the obtained auxiliary powder more concentrated, thereby giving the barium titanate high-pressure ceramic material good high-pressure resistance and good dielectric properties under high-pressure environment.

[0076] In some embodiments, the drying temperature is 80°C-180°C (e.g., it can be 80°C, 100°C, 120°C, 150°C, 160°C or 180°C, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable), and the time is 6h-18h (e.g., it can be 6h, 8h, 10h, 12h, 15h, 16h or 18h, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable).

[0077] In some embodiments, the carbon removal temperature is 450°C-800°C (e.g., it can be 450°C, 500°C, 600°C, 700°C or 800°C, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable), and the time is 8h-18h (e.g., it can be 8h, 10h, 12h, 15h, 16h or 18h, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable).

[0078] One embodiment of the present invention provides a barium titanate high-pressure ceramic material, which is prepared by the solid-state sintering preparation method described in any embodiment.

[0079] The present invention provides a high-voltage capacitor, wherein the high-voltage capacitor comprises barium titanate high-voltage ceramic material prepared by any of the solid-state sintering preparation methods described in any embodiment, or comprises barium titanate high-voltage ceramic material described in any of the embodiments.

[0080] To clearly illustrate the technical solution of the present invention, the room temperature in the following specific embodiments is 25°C.

[0081] Example 1

[0082] This embodiment provides a solid-state sintering preparation method for barium titanate high-pressure ceramic materials, the solid-state sintering preparation method comprising:

[0083] (1) Preparation of barium titanate powder:

[0084] S11: Weigh barium carbonate (median particle size D50 of 10μm) and titanium dioxide (median particle size D50 of 10μm) at a molar ratio of 1:1, perform preliminary mixing in a three-dimensional mixer, and then pulverize and mix the mixed raw materials by an air jet mill to obtain raw material powder with a median particle size D50 of 2μm.

[0085] S12: The raw material powder is loaded into a sagger and vibrated on a vibrating table to make the material fully compacted. Then, evenly distributed honeycomb-shaped vents are punched out, and the material is placed in a muffle furnace for pre-firing. The initial temperature during pre-firing is room temperature, the maximum temperature is 1200℃, the heating rate is 8℃ / min, and the material is held at the maximum temperature for 120 minutes to obtain the pre-fired billet.

[0086] S13: The pre-fired billet is successively subjected to coarse crushing by a jaw crusher, fine crushing by a roller mill, and deagglomeration by an air jet mill to obtain powder with a median particle size D50 of 2μm; then it is subjected to sand milling to reduce the median particle size D50 of the powder to 1μm.

[0087] S14: The powder after sand milling is dried at 150℃ for 10 hours, and then carbon is removed at 600℃ for 12 hours; then the carbon-removed powder is subjected to coarse crushing in a crusher and fine crushing in a roller mill to obtain barium titanate powder.

[0088] (2) Preparation of excipient powder:

[0089] S21: Weigh strontium carbonate (median particle size D50 of 10 μm) and titanium dioxide (median particle size D50 of 10 μm) in a molar ratio of 1:1 and mix them evenly in a ball mill;

[0090] S22: The powder after uniform mixing is dried at 150℃ for 10 hours, and then carbon is removed at 600℃ for 12 hours; then the carbon-removed powder is subjected to coarse crushing in a crusher and fine crushing in a roller mill to obtain auxiliary powder.

[0091] (3) Preparation of barium titanate high-pressure ceramic materials

[0092] S31: The barium titanate powder obtained in step S14 and the auxiliary powder obtained in step S24 are mixed in an air jet mill at a molar ratio of 8:1 by deagglomeration to obtain mixed raw material powder.

[0093] S32: The raw material powder is loaded into a sagger and vibrated on a vibrating table to ensure that the material is fully compacted. Then, vents with a uniform honeycomb pattern are punched out and the material is placed in a muffle furnace for sintering. The initial temperature during sintering is room temperature, the maximum temperature is 1400℃, the heating rate is 8℃ / min, and the material is held at the maximum temperature for 2 hours to obtain the barium titanate high-pressure ceramic material.

[0094] Example 2

[0095] This embodiment provides a solid-state sintering preparation method for barium titanate high-pressure ceramic materials, the solid-state sintering preparation method comprising:

[0096] (1) Preparation of barium titanate powder:

[0097] S11: Weigh barium carbonate (median particle size D50 of 3μm) and titanium dioxide (median particle size D50 of 3μm) at a molar ratio of 1:1, perform preliminary mixing in a three-dimensional mixer, and then pulverize and mix the mixed raw materials by an air jet mill to obtain raw material powder with a median particle size D50 of 0.8μm.

[0098] S12: The raw material powder is loaded into a sagger and vibrated on a vibrating table to make the material fully compacted. Then, evenly distributed honeycomb-shaped vents are punched out and the material is placed in a muffle furnace for pre-firing. The initial temperature during pre-firing is room temperature, the maximum temperature is 1150℃, the heating rate is 5℃ / min, and the material is held at the maximum temperature for 180 minutes to obtain the pre-fired billet.

[0099] S13: The pre-fired billet is successively subjected to coarse crushing by a jaw crusher, fine crushing by a roller mill, and deagglomeration by an air jet mill to obtain powder with a median particle size D50 of 0.8μm; then it is subjected to sand milling to reduce the median particle size D50 of the powder to 0.6μm.

[0100] S14: The powder after sand milling is dried at 80℃ for 18 hours, and then carbon is removed at 450℃ for 18 hours; then the carbon-removed powder is subjected to coarse crushing in a crusher and fine crushing in a roller mill to obtain barium titanate powder.

[0101] (2) Preparation of excipient powder:

[0102] S21: Weigh strontium carbonate (median particle size D50 of 3 μm) and titanium dioxide (median particle size D50 of 3 μm) in a molar ratio of 1:1 and mix them evenly in a ball mill;

[0103] S22: The uniformly mixed powder is dried at 80℃ for 18 hours, and then decarbonized at 450℃ for 18 hours; then the decarbonized powder is subjected to coarse crushing by a crusher and fine crushing by a roller mill to obtain auxiliary powder.

[0104] (3) Preparation of barium titanate high-pressure ceramic materials

[0105] S31: The barium titanate powder obtained in step S14 and the auxiliary powder obtained in step S24 are mixed in an air jet mill at a molar ratio of 8:1 by deagglomeration to obtain mixed raw material powder.

[0106] S32: The raw material powder is loaded into a sagger and vibrated on a vibrating table to ensure that the material is fully compacted. Then, vents with a uniform honeycomb pattern are punched out, and the material is placed in a muffle furnace for sintering. The initial temperature during sintering is room temperature, the maximum temperature is 1200℃, the heating rate is 2℃ / min, and the material is held at the maximum temperature for 3 hours to obtain the barium titanate high-pressure ceramic material.

[0107] Example 3

[0108] This embodiment provides a solid-state sintering preparation method for barium titanate high-pressure ceramic materials, the solid-state sintering preparation method comprising:

[0109] (1) Preparation of barium titanate powder:

[0110] S11: Weigh barium carbonate (median particle size D50 of 15μm) and titanium dioxide (median particle size D50 of 15μm) at a molar ratio of 1:1, perform preliminary mixing in a three-dimensional mixer, and then pulverize and mix the mixed raw materials by an air jet mill to obtain raw material powder with a median particle size D50 of 3.5μm.

[0111] S12: The raw material powder is loaded into a sagger and vibrated on a vibrating table to make the material fully compacted. Then, evenly distributed honeycomb-shaped vents are punched out, and the material is placed in a muffle furnace for pre-firing. The initial temperature during pre-firing is room temperature, the maximum temperature is 1350℃, the heating rate is 10℃ / min, and the material is held at the maximum temperature for 30 minutes to obtain the pre-fired billet.

[0112] S13: The pre-fired billet is successively subjected to coarse crushing by a jaw crusher, fine crushing by a roller mill, and deagglomeration by an air jet mill to obtain powder with a median particle size D50 of 3.5μm; then it is subjected to sand milling to reduce the median particle size D50 of the powder to 1.5μm.

[0113] S14: The powder after sand milling is dried at 180℃ for 6 hours, and then carbon is removed at 800℃ for 8 hours; then the carbon-removed powder is subjected to coarse crushing in a crusher and fine crushing in a roller mill to obtain barium titanate powder.

[0114] (2) Preparation of excipient powder:

[0115] S21: Weigh strontium carbonate (median particle size D50 of 15μm) and titanium dioxide (median particle size D50 of 15μm) in a molar ratio of 1:1 and mix them evenly in a ball mill;

[0116] S22: The uniformly mixed powder is dried at 180℃ for 6 hours, and then decarbonized at 800℃ for 8 hours; then the decarbonized powder is subjected to coarse crushing by a crusher and fine crushing by a roller mill to obtain auxiliary powder.

[0117] (3) Preparation of barium titanate high-pressure ceramic materials

[0118] S31: The barium titanate powder obtained in step S14 and the auxiliary powder obtained in step S24 are mixed in an air jet mill at a molar ratio of 8:1 by deagglomeration to obtain mixed raw material powder.

[0119] S32: The raw material powder is loaded into a sagger and vibrated on a vibrating table to ensure the material is fully compacted. Then, vents with a uniform honeycomb pattern are punched out, and the material is placed in a muffle furnace for sintering. The initial temperature during sintering is room temperature, the maximum temperature is 1480℃, the heating rate is 10℃ / min, and the material is held at the maximum temperature for 0.5h to obtain the barium titanate high-pressure ceramic material.

[0120] Example 4

[0121] This embodiment provides a solid-state sintering preparation method for barium titanate high-pressure ceramic materials. Except that the molar ratio of barium carbonate to titanium dioxide is 0.990:1 when preparing barium titanate powder, all other methods are the same as in Example 1.

[0122] Example 5

[0123] This embodiment provides a solid-state sintering preparation method for barium titanate high-pressure ceramic materials. Except that the molar ratio of barium carbonate to titanium dioxide is 1.010:1 when preparing barium titanate powder, all other methods are the same as in Example 1.

[0124] Example 6

[0125] This embodiment provides a solid-state sintering preparation method for barium titanate high-pressure ceramic materials. Except that the molar ratio of strontium carbonate to titanium dioxide is 0.8:1 when preparing barium titanate powder, all other methods are the same as in Example 1.

[0126] Example 7

[0127] This embodiment provides a solid-state sintering preparation method for barium titanate high-pressure ceramic materials. Except that the molar ratio of strontium carbonate to titanium dioxide is 1.2:1 when preparing barium titanate powder, all other methods are the same as in Example 1.

[0128] Example 8

[0129] This embodiment provides a solid-state sintering preparation method for barium titanate high-pressure ceramic materials. Except for the molar ratio of barium titanate powder to auxiliary powder being 5:1, the rest is the same as in Example 1.

[0130] Example 9

[0131] This embodiment provides a solid-state sintering preparation method for barium titanate high-pressure ceramic materials. Except for the molar ratio of barium titanate powder to auxiliary powder being 10:1, the rest is the same as in Example 1.

[0132] Example 10

[0133] This embodiment provides a solid-state sintering preparation method for barium titanate dielectric materials. Except for the carbon removal temperature of 400°C in step S14, the rest is the same as in Example 1.

[0134] Example 11

[0135] This embodiment provides a solid-state sintering preparation method for barium titanate dielectric materials. Except for the carbon removal temperature of 850°C in step S14, the rest is the same as in Example 1.

[0136] Example 12

[0137] This embodiment provides a solid-state sintering preparation method for barium titanate dielectric materials. Except for step S14, the method is the same as that in Example 1.

[0138] Example 13

[0139] This embodiment provides a solid-state sintering preparation method for barium titanate dielectric materials. Except for the carbon removal temperature of 400°C in step S22, the rest is the same as in Example 1.

[0140] Example 14

[0141] This embodiment provides a solid-state sintering preparation method for barium titanate dielectric materials. Except for the carbon removal temperature of 850°C in step S22, the rest is the same as in Example 1.

[0142] Example 15

[0143] This embodiment provides a solid-state sintering preparation method for barium titanate dielectric materials. Except for step S22, the method is the same as that in Example 1.

[0144] Comparative Example 1

[0145] This comparative example provides a solid-state sintering preparation method for barium titanate ceramic materials. Except for the absence of sand milling in step S13, the method is the same as that in Example 1.

[0146] Comparative Example 2

[0147] This comparative example provides a solid-state sintering preparation method for barium titanate ceramic materials, the solid-state sintering preparation method comprising:

[0148] S11: Weigh barium carbonate (median particle size D50 of 10μm), strontium carbonate (median particle size D50 of 10μm), and titanium dioxide (median particle size D50 of 10μm) according to a molar ratio of 1:1:2, perform preliminary mixing in a three-dimensional mixer, and then pulverize the mixed raw materials through an air jet mill to obtain raw material powder with a median particle size D50 of 2μm;

[0149] S12: The raw material powder is loaded into a sagger and vibrated on a vibrating table to make the material fully compacted. Then, evenly distributed honeycomb-shaped vents are punched out, and the material is placed in a muffle furnace for pre-firing. The initial temperature during pre-firing is room temperature, the maximum temperature is 1200℃, the heating rate is 8℃ / min, and the material is held at the maximum temperature for 120 minutes to obtain the pre-fired billet.

[0150] S13: The pre-fired billet is successively subjected to coarse crushing by a jaw crusher, fine crushing by a roller mill, and deagglomeration by an air jet mill to obtain powder with a median particle size D50 of 2μm; then it is subjected to sand milling to reduce the median particle size D50 of the powder to 1μm.

[0151] S14: The powder after sand milling is dried at 150℃ for 10 hours, and then carbon is removed at 600℃ for 12 hours; then the carbon-removed powder is subjected to coarse crushing by a crusher and fine crushing by a roller mill to obtain raw material powder.

[0152] S15: The raw material powder is loaded into a sagger and vibrated on a vibrating table to ensure the material is fully compacted. Then, evenly distributed honeycomb-shaped vents are punched out, and the material is placed in a muffle furnace for sintering. The initial temperature during sintering is room temperature, the maximum temperature is 1400℃, the heating rate is 8℃ / min, and the material is held at the maximum temperature for 2 hours to obtain the barium titanate ceramic material.

[0153] Comparative Example 3

[0154] This comparative example provides a solid-state sintering preparation method for barium titanate ceramic materials, the solid-state sintering preparation method comprising:

[0155] S11: Weigh barium carbonate (median particle size D50 of 10μm) and titanium dioxide (median particle size D50 of 10μm) at a molar ratio of 1:1, perform preliminary mixing in a three-dimensional mixer, and then pulverize and mix the mixed raw materials by an air jet mill to obtain raw material powder with a median particle size D50 of 2μm.

[0156] S12: The raw material powder is loaded into a sagger and vibrated on a vibrating table to make the material fully compacted. Then, evenly distributed honeycomb-shaped vents are punched out, and the material is placed in a muffle furnace for pre-firing. The initial temperature during pre-firing is room temperature, the maximum temperature is 1200℃, the heating rate is 8℃ / min, and the material is held at the maximum temperature for 120 minutes to obtain the pre-fired billet.

[0157] S13: The pre-fired billet is successively subjected to coarse crushing by a jaw crusher, fine crushing by a roller mill, and deagglomeration by an air jet mill to obtain powder with a median particle size D50 of 2μm; then it is subjected to sand milling to reduce the median particle size D50 of the powder to 1μm.

[0158] S14: The powder after sand milling is dried at 150℃ for 10 hours, and then carbon is removed at 600℃ for 12 hours; then the carbon-removed powder is subjected to coarse crushing in a crusher and fine crushing in a roller mill to obtain barium titanate powder.

[0159] S15: Barium titanate powder is loaded into a sagger and vibrated on a vibrating table to ensure the material is fully compacted. Then, vents with a uniform honeycomb pattern are punched out, and the material is placed in a muffle furnace for sintering. The initial temperature during sintering is room temperature, the maximum temperature is 1400℃, the heating rate is 10℃ / min, and the material is held at the maximum temperature for 2 hours to obtain the barium titanate ceramic material.

[0160] Performance Characterization

[0161] The barium titanate ceramic materials obtained in the above embodiments and comparative examples were sequentially subjected to coarse crushing by a jaw crusher, fine crushing by a roller mill, and deagglomeration by an air jet mill to obtain barium titanate ceramic particles with a median particle size D50 of 1 μm. Then, they were pressed into disc samples with a diameter of 30 mm and a thickness of 4 mm under a pressure of 20 MPa. The dielectric properties of the disc samples were tested in a temperature range of -55℃ to 200℃, and the results are shown in Table 1.

[0162] Table 1

[0163]

[0164]

[0165] In summary, the solid-state sintering preparation method provided by this invention can improve the dielectric properties and high-voltage resistance of barium titanate ceramics under high-voltage environments using only simple auxiliary materials. Moreover, the solid-state sintering preparation method provided by this invention is simple and easy to implement, enabling the industrial-scale production of barium titanate high-voltage ceramic materials. Furthermore, the solid-state sintering preparation method provided by this invention performs drying, carbon removal, and crushing treatments on both barium titanate powder and auxiliary powder during preparation, thereby improving the median particle size distribution of the raw materials and enhancing the high-voltage resistance and dielectric properties of barium titanate ceramics under high-voltage environments.

[0166] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A solid-state sintering preparation method for barium titanate high-pressure ceramic materials, characterized in that, The solid-state sintering preparation method includes: Barium titanate powder and auxiliary powder are mixed, and the resulting mixed powder is sintered to obtain the barium titanate high-pressure ceramic material. The barium titanate powder is prepared by the following solid-state sintering method: mixing barium source and titanium source to obtain raw material powder; then pre-firing the raw material powder to obtain pre-firing blank; the pre-firing blank is subjected to a first crushing treatment, grinding, carbon removal treatment and a second crushing treatment in sequence to obtain the barium titanate powder. The auxiliary powder is prepared by the following solid-state sintering method: strontium carbonate and titanium dioxide are mixed according to the formula, the mixed powder is dried and decarbonized, and then subjected to a third crushing process to obtain the auxiliary powder. The auxiliary powder comprises strontium carbonate and titanium dioxide in a molar ratio of 0.8:1 to 1.2:1; The molar ratio of barium titanate powder to auxiliary powder is 5:1-10:

1.

2. The solid-state sintering preparation method according to claim 1, characterized in that, The heating rate of the sintering process is 2℃ / min-10℃ / min; And / or, the maximum temperature of the sintering treatment is 1200℃-1480℃; And / or, the holding time at the highest temperature during the sintering process is 0.5h-3h.

3. The solid-state sintering preparation method according to claim 1, characterized in that, The barium source includes barium carbonate and / or barium oxide; And / or, the titanium source includes titanium dioxide; And / or, the molar ratio of Ba in the barium source to Ti in the titanium source is 0.990:1-1.010:1; And / or, the median particle size D50 of the raw material powder is 0.8μm-3.5μm.

4. The solid-state sintering preparation method according to claim 1, characterized in that, The preheating rate is 5℃ / min-10℃ / min; And / or, the maximum pre-firing temperature is 1150℃-1350℃; And / or, the preheating time at the highest temperature is 30 min to 180 min; And / or, the method of the first crushing process includes depolymerization; And / or, the median particle size D50 of the powder after the first crushing treatment is 0.8μm-3.5μm.

5. The solid-state sintering preparation method according to claim 1, characterized in that, The grinding method includes sand milling; the median particle size D50 of the powder obtained by sand milling is 0.6μm-1.5μm; And / or, the carbon removal treatment includes: performing carbon removal at 450℃-800℃ for 8h-18h; And / or, the carbon removal process further includes drying prior to carbon removal: drying at a temperature of 80℃-180℃ for 6h-18h.

6. The solid-state sintering preparation method according to claim 1, characterized in that, The drying process is carried out at a temperature of 80℃-180℃ for 6h-18h. And / or, the carbon removal temperature is 450℃-800℃, and the time is 8h-18h.

7. A barium titanate high-pressure ceramic material, characterized in that, The barium titanate high-pressure ceramic material is prepared by the solid-state sintering preparation method according to any one of claims 1-6.

8. A high-voltage capacitor, characterized in that, The high-voltage capacitor includes barium titanate high-voltage ceramic material prepared by the solid-state sintering preparation method according to any one of claims 1-6, or includes barium titanate high-voltage ceramic material according to claim 7.

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