Barium titanate high-voltage ceramic material as well as solid-phase sintering preparation method and application thereof

Abstract

The invention relates to a barium titanate high-voltage ceramic material as well as a solid-phase sintering preparation method and application thereof, and the solid-phase sintering preparation method comprises the following steps: mixing barium titanate powder and auxiliary material powder, and sintering the obtained mixed powder to obtain the barium titanate high-voltage ceramic material, the auxiliary material powder comprises strontium carbonate and titanium dioxide in a molar ratio of (0.8: 1)-(1.2: 1); the molar ratio of the barium titanate powder to the auxiliary material powder is (5: 1)-(10: 1). The dielectric property and the high-voltage resistance of the barium titanate ceramic in a high-voltage environment can be improved only by using simple auxiliary materials; in addition, the solid-phase sintering preparation method provided by the invention is simple and easy to implement, and can realize industrial large-scale production of the barium titanate high-voltage ceramic material.

Description

Technical Field

[0001] The present invention belongs to the technical field of ceramic capacitors, relates to a high-voltage ceramic material, and particularly relates to a barium titanate high-voltage ceramic material, a solid-phase sintering preparation method thereof, and an application thereof. Background Art

[0002] High-voltage ceramic capacitors are widely used in focusing circuits, high-voltage power supply circuits, and pulse energy processing devices, and are required to have the characteristics of high breakdown voltage, high dielectric constant, low loss, high energy storage, and high stability. Barium titanate materials have a relatively high dielectric constant and can store the maximum electrical energy in a very small volume, so they are widely used as the core dielectric materials of energy storage capacitors. However, unmodified barium titanate ceramics have significant defects: their dielectric properties are highly sensitive to DC bias and temperature changes, the dielectric constant change rate is large, and the breakdown field strength is relatively low, making it difficult to meet the reliability requirements of high-voltage capacitors. Therefore, barium titanate ceramics must be modified to be suitable for high-voltage ceramic capacitors.

[0003] Most of the existing technologies use the liquid-phase synthesis method for the industrial production of modified barium titanate ceramic materials. However, the liquid-phase synthesis method has high raw material costs, complex processing techniques, requires high pressure and temperature, resulting in high investment and construction scale costs. At the same time, a large amount of wastewater needs to be discharged during the hydrothermal synthesis process, causing serious environmental pollution. Compared with liquid-phase synthesis, solid-phase sintering has high sintering efficiency, rich raw material sources, small one-time investment, simple process, high degree of process automation, and low labor intensity, making it easier to achieve industrialized and large-scale production. However, there is no industrial method for producing barium titanate high-voltage ceramic materials.

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

[0005] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a barium titanate high-voltage ceramic material, a solid-phase sintering preparation method thereof, and an application thereof. The solid-phase sintering preparation method can enable the barium titanate high-voltage ceramic material to have good dielectric properties and high-voltage resistance in a high-voltage environment; at the same time, it is also conducive to realizing industrialized scale production.

[0006] To achieve the purpose of the present invention, the following technical solutions are adopted:

[0007] In the first aspect, the present invention provides a solid-phase sintering preparation method of a barium titanate high-voltage ceramic material, and the solid-phase sintering preparation method includes:

[0008] Mix barium titanate powder and auxiliary material powder, and the obtained mixed powder is sintered to obtain the barium titanate high-voltage ceramic material;

[0009] The auxiliary material powder includes strontium carbonate and titanium dioxide with a molar ratio of 0.8:1 - 1.2:1;

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

[0011] The solid-phase sintering preparation method provided by the present invention can improve the dielectric properties and high-voltage resistance of barium titanate ceramics in a high-voltage environment only by simply using auxiliary materials; moreover, the solid-phase sintering preparation method provided by the present invention is simple and feasible, and can realize the industrial-scale production of barium titanate high-voltage ceramic materials.

[0012] Preferably, the heating rate of the sintering treatment is 2°C / min - 10°C / min.

[0013] Preferably, the highest temperature of the sintering treatment is 1200°C - 1480°C.

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

[0015] Preferably, the barium titanate powder is prepared by the following solid-phase sintering preparation method: mixing a barium source and a titanium source to obtain a raw material powder; then performing a pre-sintering treatment on the raw material powder to obtain a pre-sintered blank; and sequentially performing a first crushing treatment, grinding, carbon removal treatment, and a second crushing treatment on the pre-sintered blank 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 0.8 μm - 3.5 μm.

[0020] Preferably, the heating rate of the pre-sintering is 5°C / min - 10°C / min.

[0021] Preferably, the highest temperature of the pre-sintering is 1150°C - 1350°C.

[0022] Preferably, the holding time at the highest temperature of the pre-sintering is 30 min - 180 min.

[0023] Preferably, the method of the first crushing treatment includes depolymerization.

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

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

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

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

[0028] Preferably, the auxiliary material powder is prepared by the following solid-phase sintering preparation method: mixing strontium carbonate and titanium dioxide according to the formula amount, drying and removing carbon from the mixed powder, and then performing a third crushing treatment to obtain the auxiliary material powder.

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

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

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

[0032] In a third aspect, the present invention provides a high-voltage capacitor, which includes the barium titanate high-voltage ceramic material prepared by the solid-phase sintering preparation method described in the first aspect, or includes the barium titanate high-voltage ceramic material described in the second aspect.

[0033] The numerical ranges described in the present invention not only include the specific point values exemplified above, but also include any point values between the above numerical ranges not exemplified. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list 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-phase sintering preparation method provided by the present invention can improve the dielectric properties and high-voltage resistance properties of barium titanate ceramics in a high-voltage environment only by using simple auxiliary materials; moreover, the solid-phase sintering preparation method provided by the present invention is simple and feasible, and can realize the industrial-scale production of barium titanate high-voltage ceramic materials. Specific Embodiments

[0036] The technical solution of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0037] An embodiment of the present invention provides a solid-phase sintering preparation method for a barium titanate high-voltage ceramic material. The solid-phase sintering preparation method includes:

[0038] Mix barium titanate powder and auxiliary material powder, and the obtained mixed powder is sintered to obtain the barium titanate high-voltage ceramic material;

[0039] The auxiliary material powder includes strontium carbonate and titanium dioxide with a molar ratio of 0.8:1 - 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 numerical range are equally applicable.

[0040] The molar ratio of the barium titanate powder to the auxiliary material 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 numerical range are equally applicable.

[0041] The solid-phase sintering preparation method provided by the present invention can improve the dielectric properties and high-voltage resistance of barium titanate ceramics in a high-voltage environment only by simply using auxiliary materials; moreover, the solid-phase sintering preparation method provided by the present invention is simple and feasible and can realize the industrial-scale production of barium titanate high-voltage ceramic materials.

[0042] In some embodiments, the heating rate of the sintering treatment is 2°C / min - 10°C / min. For example, it can be 2°C / min, 4°C / min, 5°C / min, 6°C / min, 8°C / min, or 10°C / min, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0043] In some embodiments, the highest temperature of the sintering treatment is 1200°C - 1480°C. For example, it can be 1200°C, 1250°C, 1300°C, 1350°C, 1400°C, 1450°C, or 1480°C, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0044] In some embodiments, the holding time at the highest temperature of the sintering treatment 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 numerical range are equally applicable.

[0045] In some embodiments, the barium titanate powder is prepared by the following solid-phase sintering preparation method: mixing a barium source and a titanium source to obtain a raw material powder; then performing a pre-sintering treatment on the raw material powder to obtain a pre-sintered blank; and sequentially performing a first crushing treatment, grinding, carbon removal treatment, and a second crushing treatment on the pre-sintered blank to obtain the barium titanate powder.

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

[0047] Among them, the pre-sintering treatment causes a solid-phase reaction between the titanium source and the barium source and removes moisture, volatile impurities, gases, and some organic substances existing inside the raw materials, thereby improving the purity of the prepared barium titanate powder; in addition, the barium titanate powder obtained by the pre-sintering treatment better cooperates with the auxiliary material powder during subsequent sintering, so that the barium titanate high-voltage ceramic material has good dielectric properties under a high-voltage environment.

[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 - 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, and the other unlisted values within the numerical range are equally applicable.

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

[0052] In order to obtain a raw material powder with a median particle size D50 satisfying 0.8 μm - 3.5 μm, the mixing of the barium source and the titanium source is first carried out in a three-dimensional mixer, and then an air jet mill is used to obtain a raw material powder with a median particle size D50 satisfying 0.8 μm - 3.5 μm.

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

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

[0055] In some embodiments, the heating rate of the pre - firing is 5 °C / min - 10 °C / min. For example, it can be 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. The other unlisted values within the numerical range are equally applicable.

[0056] In the present invention, the starting temperature of the pre - firing is room temperature. For example, it can be 15 °C - 30 °C. For example, it can be 15 °C, 18 °C, 20 °C, 25 °C, 28 °C, or 30 °C, but is not limited to the listed values. The other unlisted values within the numerical range are equally applicable.

[0057] In some embodiments, the maximum temperature of the pre - firing 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. The other unlisted values within the numerical range are equally applicable.

[0058] In some embodiments, the heat - preservation time at the maximum temperature of the pre - firing is 30 min - 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. The other unlisted values within the numerical range are equally applicable.

[0059] In some embodiments, the method of the first crushing treatment includes depolymerization.

[0060] Exemplarily, the depolymerization is carried out in a jet mill.

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

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

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

[0064] The present invention does not specifically limit parameters such as the method and time of sand grinding, as long as the median particle size D50 of the powder obtained by sand grinding is 0.6 μm - 1.5 μm. Generally speaking, controlling the sand grinding time to be 30 min - 180 min can achieve the technical effect that the median particle size D50 of the material obtained by sand grinding is 0.6 μm - 1.5 μm.

[0065] Grinding can further refine the particle size of barium titanate powder. During the process of continuous refinement of its particle size, the specific surface area increases, which is beneficial to obtaining a dense barium titanate high-voltage ceramic material in subsequent sintering. However, during the process of continuous refinement of the particle size, fine particles re-agglomerate under the influence of van der Waals force, double-layer electrostatic interaction, etc. Therefore, as a preferred technical solution, a dispersant is used during grinding to prevent the mutual aggregation of barium titanate powder. Therefore, a carbon removal treatment needs to be carried out after grinding to remove the dispersant.

[0066] The present invention does not specifically limit the dosage and type of the dispersant, as long as the dispersion effect during grinding can be achieved.

[0067] In some embodiments, the carbon removal treatment includes: performing carbon removal at 450°C - 800°C for 8 h - 18 h.

[0068] The temperature of the carbon removal is 450°C - 800°C. For example, it can be 450°C, 500°C, 600°C, 700°C, or 800°C, but is not limited to the listed values, and the other unlisted values within the numerical range are equally applicable.

[0069] The time of the carbon removal is 8 h - 18 h. For example, it can be 8 h, 10 h, 12 h, 15 h, 16 h, or 18 h, but is not limited to the listed values, and the other unlisted values within the numerical range are equally applicable.

[0070] In some embodiments, water is used as the grinding medium in the grinding process. Water has a good dispersing effect. During the grinding process, it adsorbs on the surface of solid particles, reducing the interfacial tension between liquid-liquid and solid-liquid, making the surface of agglomerated solid particles easy to wet, preventing the mutual agglomeration of fine particles. However, the residual moisture is not conducive to subsequent sintering.

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

[0072] The drying temperature is 80°C - 180°C. For example, it can be 80°C, 100°C, 120°C, 150°C, 160°C or 180°C, but is not limited to the listed values. Other unlisted values within the numerical range are equally 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 numerical range are equally applicable.

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

[0075] The solid-phase sintering preparation method provided by the present invention can make the particle size distribution of the obtained auxiliary material powder more concentrated by adopting a specific solid-phase sintering preparation method for the auxiliary material powder, so that the barium titanate high-voltage ceramic material has good high-voltage resistance performance and good dielectric performance under high-voltage environment.

[0076] In some embodiments, the drying temperature is 80°C - 180°C (for example, it can be 80°C, 100°C, 120°C, 150°C, 160°C or 180°C, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable), and the 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 numerical range are equally applicable).

[0077] In some embodiments, the carbon removal temperature is 450°C - 800°C (for example, it can be 450°C, 500°C, 600°C, 700°C or 800°C, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable), and the 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 numerical range are equally applicable).

[0078] An embodiment of the present invention provides a barium titanate high-voltage ceramic material, which is prepared by the solid-phase sintering preparation method described in any one of the embodiments.

[0079] The present invention provides a high-voltage capacitor, which includes the barium titanate high-voltage ceramic material prepared by the solid-phase sintering preparation method described in any one of the embodiments, or includes the barium titanate high-voltage ceramic material described in any one of the embodiments.

[0080] For clearly illustrating the technical solution of the present invention, the normal temperature in the following specific embodiments is 25°C.

[0081] Example 1

[0082] This embodiment provides a solid-phase sintering preparation method for a barium titanate high-voltage ceramic material, and the solid-phase sintering preparation method includes:

[0083] (1) Preparing barium titanate powder:

[0084] S11: Weigh barium carbonate (median particle size D50 is 10 μm) and titanium dioxide (median particle size D50 is 10 μm) according to a molar ratio of 1:1, perform preliminary mixing in a three-dimensional mixer, and then crush and mix the mixed raw materials through an air-flow crusher to obtain raw material powder with a median particle size D50 of 2 μm;

[0085] S12: Load the raw material powder into a crucible, vibrate and compact it on a vibrating table to make the material fully dense, then punch out exhaust ports arranged in a uniform honeycomb pattern, and place it in a muffle furnace for pre-sintering; the initial temperature during pre-sintering is normal temperature, the highest temperature is 1200°C, the heating rate is 8°C / min, keep the temperature at the highest temperature for heat preservation, and the heat preservation time is 120 min to obtain a pre-sintered blank;

[0086] S13: The pre-sintered blank is successively subjected to coarse crushing by a jaw crusher, fine crushing by a pair-roller machine, and depolymerization by an air-flow crusher to obtain powder with a median particle size D50 of 2 μm; then perform sanding treatment to reduce the median particle size D50 of the powder to 1 μm;

[0087] S14: Dry the sanded powder at a temperature of 150°C for 10 h, and then remove carbon at a temperature of 600°C for 12 h; then perform coarse crushing of the powder after carbon removal by a crusher and fine crushing by a pair-roller machine to obtain barium titanate powder;

[0088] (2) Preparing auxiliary material powder:

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

[0090] S22: The powder after being evenly mixed is dried at a temperature of 150 °C for 10 h, and then carbon is removed at a temperature of 600 °C for 12 h; then the powder after carbon removal is roughly crushed by a crusher and finely crushed by a pair-roller machine to obtain auxiliary material powder;

[0091] (3) Preparation of barium titanate high-voltage ceramic material

[0092] S31: The barium titanate powder obtained in step S14 and the auxiliary material powder obtained in step S24 are mixed in a jet mill in a way of depolymerization according to a molar ratio of 8:1 to obtain mixed raw material powder;

[0093] S32: The raw material powder is filled into a sagger, vibrated and compacted on a vibrating table to make the material fully dense, and then exhaust ports with uniform honeycomb arrangement are punched out and put into a muffle furnace for sintering treatment; the initial temperature during sintering treatment is room temperature, the highest temperature is 1400 °C, the heating rate is 8 °C / min, and when the highest temperature is reached, heat preservation is carried out for 2 h to obtain the barium titanate high-voltage ceramic material.

[0094] Example 2

[0095] This example provides a solid-phase sintering preparation method of barium titanate high-voltage ceramic material, and the solid-phase sintering preparation method includes:

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

[0097] S11: Barium carbonate (median particle size D50 is 3 μm) and titanium dioxide (median particle size D50 is 3 μm) are weighed according to a molar ratio of 1:1, and are preliminarily mixed in a three-dimensional mixer, and then the mixed raw materials are crushed and mixed by a jet mill to obtain raw material powder with a median particle size D50 of 0.8 μm;

[0098] S12: The raw material powder is filled into a sagger, vibrated and compacted on a vibrating table to make the material fully dense, and then exhaust ports with uniform honeycomb arrangement are punched out and put into a muffle furnace for pre-sintering; the initial temperature during pre-sintering is room temperature, the highest temperature is 1150 °C, the heating rate is 5 °C / min, and when the highest temperature is reached, heat preservation is carried out for 180 min to obtain a pre-sintered blank;

[0099] S13: The pre-sintered blank is successively roughly crushed by a jaw crusher, finely crushed by a pair-roller machine and depolymerized by a jet mill to obtain powder with a median particle size D50 of 0.8 μm; then grinding treatment is carried out to reduce the median particle size D50 of the powder to 0.6 μm;

[0100] S14: The ground powder is dried at 80 °C for 18 h and then degassed at 450 °C for 18 h. Then, the degassed powder is roughly crushed by a crusher and finely crushed by a roll crusher to obtain barium titanate powder.

[0101] (2) Preparation of auxiliary material powder:

[0102] S21: Strontium carbonate (median particle size D50 = 3 μm) and titanium dioxide (median particle size D50 = 3 μm) are weighed according to a molar ratio of 1:1 and mixed evenly in a ball mill.

[0103] S22: The evenly mixed powder is dried at 80 °C for 18 h and then degassed at 450 °C for 18 h. Then, the degassed powder is roughly crushed by a crusher and finely crushed by a roll crusher to obtain auxiliary material powder.

[0104] (3) Preparation of barium titanate high-voltage ceramic material

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

[0106] S32: The raw material powder is filled into a sagger, vibrated and compacted on a vibrating table to make the material fully dense, and then exhaust holes with a uniform honeycomb arrangement are punched out and placed in a muffle furnace for sintering treatment. The initial temperature during sintering treatment is room temperature, the maximum temperature is 1200 °C, the heating rate is 2 °C / min, and it is kept at the maximum temperature for 3 h to obtain the barium titanate high-voltage ceramic material.

[0107] Example 3

[0108] This example provides a solid-phase sintering preparation method for a barium titanate high-voltage ceramic material. The solid-phase sintering preparation method includes:

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

[0110] S11: Barium carbonate (median particle size D50 = 15 μm) and titanium dioxide (median particle size D50 = 15 μm) are weighed according to a molar ratio of 1:1, preliminarily mixed in a three-dimensional mixer, and then the mixed raw materials are crushed and mixed by a jet mill to obtain raw material powder with a median particle size D50 of 3.5 μm.

[0111] S12: Load the raw material powder into the sagger, vibrate and compact it on the vibrating compactor to make the material fully dense, then punch out exhaust holes arranged in a uniform honeycomb pattern, and place it in a muffle furnace for pre-sintering; the initial temperature during pre-sintering is room temperature, the maximum temperature is 1350 °C, the heating rate is 10 °C / min, keep the temperature at the maximum temperature for heat preservation, and the heat preservation time is 30 min to obtain a pre-sintered blank;

[0112] S13: The pre-sintered blank is successively subjected to coarse crushing by a jaw crusher, fine crushing by a pair-roll crusher and depolymerization by a jet mill to obtain a powder with a median particle size D50 of 3.5 μm; then perform sanding treatment to reduce the median particle size D50 of the powder to 1.5 μm;

[0113] S14: Dry the sanded powder at a temperature of 180 °C for 6 h, and then remove carbon at a temperature of 800 °C for 8 h; then perform coarse crushing of the powder after carbon removal by a crusher and fine crushing by a pair-roll crusher to obtain barium titanate powder;

[0114] (2) Prepare the auxiliary material powder:

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

[0116] S22: Dry the evenly mixed powder at a temperature of 180 °C for 6 h, and then remove carbon at a temperature of 800 °C for 8 h; then perform coarse crushing of the powder after carbon removal by a crusher and fine crushing by a pair-roll crusher to obtain the auxiliary material powder;

[0117] (3) Prepare the barium titanate high-voltage ceramic material

[0118] S31: Mix the barium titanate powder obtained in step S14 and the auxiliary material powder obtained in step S24 in a jet mill in a depolymerization manner according to a molar ratio of 8:1 to obtain a mixed raw material powder;

[0119] S32: Load the raw material powder into the sagger, vibrate and compact it on the vibrating compactor to make the material fully dense, then punch out exhaust holes arranged in a uniform honeycomb pattern, and place it in a muffle furnace for sintering treatment; the initial temperature during sintering treatment is room temperature, the maximum temperature is 1480 °C, the heating rate is 10 °C / min, keep the temperature at the maximum temperature for heat preservation, and the heat preservation time is 0.5 h to obtain the barium titanate high-voltage ceramic material.

[0120] Example 4

[0121] This example provides a solid-phase sintering preparation method of a barium titanate high-voltage ceramic material. Except that the molar ratio of barium carbonate to titanium dioxide is 0.990:1 when preparing barium titanate powder, the rest are the same as in Example 1.

[0122] Example 5

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

[0124] Example 6

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

[0126] Example 7

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

[0128] Example 8

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

[0130] Example 9

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

[0132] Example 10

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

[0134] Example 11

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

[0136] Example 12

[0137] This example provides a solid-phase sintering preparation method for barium titanate dielectric materials. Except that step S14 is not carried out, the rest are the same as in Example 1.

[0138] Example 13

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

[0140] Embodiment 14

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

[0142] Embodiment 15

[0143] This embodiment provides a solid-phase sintering preparation method for barium titanate dielectric materials. Except that step S22 is not carried out, the rest are the same as in Embodiment 1.

[0144] Comparative Example 1

[0145] This comparative example provides a solid-phase sintering preparation method for barium titanate ceramic materials. Except that the sanding in step S13 is not carried out, the rest are the same as in Embodiment 1.

[0146] Comparative Example 2

[0147] This comparative example provides a solid-phase sintering preparation method for barium titanate ceramic materials. The solid-phase sintering preparation method includes:

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

[0149] S12: Load the raw material powder into a sagger, vibrate and compact it on a vibrating table to make the material fully dense, then punch out exhaust holes arranged in a uniform honeycomb pattern, and place it in a muffle furnace for pre-sintering; the initial temperature during pre-sintering is room temperature, the highest temperature is 1200 °C, the heating rate is 8 °C / min. When the highest temperature is reached, keep it warm for 120 min to obtain a pre-sintered blank;

[0150] S13: The pre-sintered blank is successively subjected to coarse crushing by a jaw crusher, fine crushing by a pair-roll crusher, and deflocculation by an air-flow crusher to obtain powder with a median particle size D50 of 2 μm; then carry out sanding treatment to reduce the median particle size D50 of the powder to 1 μm;

[0151] S14: The sanded powder is dried at a temperature of 150 °C for 10 h, and then carbon is removed at a temperature of 600 °C for 12 h; then the carbon-removed powder is subjected to coarse crushing by a crusher and fine crushing by a pair-roll crusher to obtain raw material powder;

[0152] S15: The raw material powder is filled into a crucible, vibrated and compacted on a vibrating table to make the material fully dense, and then exhaust holes arranged in a uniform honeycomb pattern are punched out, and then it is placed in a muffle furnace for sintering treatment; the initial temperature during the sintering treatment is room temperature, the highest temperature is 1400 °C, the heating rate is 8 °C / min, and it is kept warm when the highest temperature is reached, and the holding time is 2 h to obtain the barium titanate ceramic material.

[0153] Comparative Example 3

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

[0155] S11: Weigh barium carbonate (median particle size D50 is 10 μm) and titanium dioxide (median particle size D50 is 10 μm) according to a molar ratio of 1:1, and perform preliminary mixing in a three-dimensional mixer, and then crush and mix the mixed raw materials through an air flow crusher to obtain raw material powder with a median particle size D50 of 2 μm;

[0156] S12: The raw material powder is filled into a crucible, vibrated and compacted on a vibrating table to make the material fully dense, and then exhaust holes arranged in a uniform honeycomb pattern are punched out, and then it is placed in a muffle furnace for pre-sintering; the initial temperature during the pre-sintering is room temperature, the highest temperature is 1200 °C, the heating rate is 8 °C / min, and it is kept warm when the highest temperature is reached, and the holding time is 120 min to obtain a pre-sintered blank;

[0157] S13: The pre-sintered blank is successively subjected to coarse crushing by a jaw crusher, fine crushing by a pair-roll crusher, and deflocculation by an air flow crusher to obtain powder with a median particle size D50 of 2 μm; then it is subjected to sanding treatment to reduce the median particle size D50 of the powder to 1 μm;

[0158] S14: The sanded powder is dried at a temperature of 150 °C for 10 h, and then carbon is removed at a temperature of 600 °C for 12 h; then the powder after carbon removal is subjected to coarse crushing by a crusher and fine crushing by a pair-roll crusher to obtain barium titanate powder;

[0159] S15: The barium titanate powder is filled into a crucible, vibrated and compacted on a vibrating table to make the material fully dense, and then exhaust holes arranged in a uniform honeycomb pattern are punched out, and then it is placed in a muffle furnace for sintering treatment; the initial temperature during the sintering treatment is room temperature, the highest temperature is 1400 °C, the heating rate is 10 °C / min, and it is kept warm when the highest temperature is reached, and the holding time is 2 h to obtain the barium titanate ceramic material.

[0160] Performance Characterization

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

[0162] Table 1

[0163]

[0164]

[0165] In summary, the solid-phase sintering preparation method provided by the invention can improve the dielectric properties and high-voltage resistance of barium titanate ceramics only by using simple auxiliary materials; moreover, the solid-phase sintering preparation method provided by the invention is simple and feasible, and can realize the industrial-scale production of barium titanate high-voltage ceramic materials; moreover, the solid-phase sintering preparation method provided by the invention performs drying, carbon removal, and crushing treatments on barium titanate powder and auxiliary material powder respectively, improving the median particle size distribution of the raw materials, thereby improving the high-voltage resistance and dielectric properties of barium titanate ceramics in a high-voltage environment.

[0166] The applicant declares that the above description is only the specific implementation manner 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 thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A solid-phase sintering preparation method for a barium titanate high-voltage ceramic material, characterized in that, The solid-phase sintering preparation method includes: Mixing barium titanate powder and auxiliary material powder, and subjecting the obtained mixed powder to sintering treatment to obtain the barium titanate high-voltage ceramic material; The auxiliary material powder includes strontium carbonate and titanium dioxide with a molar ratio of 0.8:1 - 1.2:1; The molar ratio of the barium titanate powder to the auxiliary material powder is 5:1 - 10:

1.

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

3. The solid-phase sintering preparation method according to claim 1, characterized in that The barium titanate powder is prepared by the following solid-phase sintering preparation method: Mixing a barium source and a titanium source to obtain raw material powder; then subjecting the raw material powder to pre-sintering treatment to obtain a pre-sintered blank; and sequentially performing a first crushing treatment, grinding, carbon removal treatment, and a second crushing treatment on the pre-sintered blank to obtain the barium titanate powder.

4. The solid-phase sintering preparation method according to claim 3, 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.

5. The solid-phase sintering preparation method according to claim 3, characterized in that, The heating rate of the pre-sintering is 5°C / min - 10°C / min; And / or, the highest temperature of the pre-sintering is 1150°C - 1350°C; And / or, the holding time at the highest temperature of the pre-sintering is 30min - 180min; And / or, the method of the first crushing treatment includes depolymerization; And / or, the median particle size D50 of the powder after the first crushing treatment is 0.8μm - 3.5μm.

6. The solid-phase sintering preparation method according to claim 3, characterized in that, The method of the grinding includes sand grinding; the median particle size D50 of the powder obtained by the sand grinding is 0.6μm - 1.5μm. And / or, the carbon removal treatment includes: performing carbon removal at 450°C - 800°C for 8h - 18h; And / or, the carbon removal treatment further includes drying before carbon removal: drying at a temperature of 80°C - 180°C for 6h - 18h.

7. The solid-phase sintering preparation method according to claim 1, wherein The auxiliary material powder is prepared by the following solid-phase sintering preparation method: Mixing strontium carbonate and titanium dioxide according to the formula amount, drying and carbon removing the mixed powder, and then performing a third crushing treatment to obtain the auxiliary material powder.

8. The solid-phase sintering preparation method according to claim 7, wherein, The temperature of the drying is 80°C - 180°C, and the time is 6h - 18h; And / or, the temperature of the carbon removal is 450°C - 800°C, and the time is 8h - 18h.

9. A barium titanate high-voltage ceramic material, characterized in that, The barium titanate high-voltage ceramic material is prepared by the solid-phase sintering preparation method according to any one of claims 1 - 8.

10. A high-voltage capacitor, characterized in that, The high-voltage capacitor includes the barium titanate high-voltage ceramic material prepared by the solid-phase sintering preparation method according to any one of claims 1 - 8, or includes the barium titanate high-voltage ceramic material according to claim 9.

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