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

Abstract

The invention relates to a barium titanate high-frequency 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 additive powder, and sintering the obtained mixed powder to obtain the barium titanate high-frequency ceramic material, the additive powder is prepared from the following raw materials: BaCO3, Li2CO3 and Nb2O5 according to a molar ratio of (7 to 9): 1: (2 to 4); the molar ratio of the barium titanate powder to the additive powder is (80: 1)-(99: 1). The dielectric property of the barium titanate ceramic in a high-frequency environment can be improved only by using simple auxiliary materials; moreover, 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-frequency ceramic material.

Description

Technical Field

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

[0002] In recent years, high-frequency ceramic capacitors have been widely used in focusing circuits, high-voltage power supply circuits, and devices for processing pulsed energy. The requirements for ceramics in such applications include: low high-frequency dielectric loss, a large dielectric constant, and a suitable temperature coefficient. The higher the dielectric coefficient of traditional BaTiO3 ceramics, the greater the dielectric loss, which directly affects the service life, stability, and safety of capacitors made of BaTiO3 as raw materials in a high-frequency environment.

[0003] The prior art usually uses materials such as Mg2TiO4, CaSrO3, SrZrO3, and CaSnO3 to adjust the temperature stability. However, the dielectric constants of these materials themselves are only 15 - 30, and it is difficult to obtain a barium titanate high-frequency ceramic material with a large dielectric constant and high temperature stability. Although adding temperature-stable materials such as Bi2O3·2TiO2 and PbTiO3 can obtain high dielectric performance and temperature stability, the addition of these materials will also lead to an increase in dielectric loss and instability, and they are not suitable for use in a high-frequency environment.

[0004] Most of the prior art uses 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, and is more likely to achieve industrialized and large-scale production. However, there is no industrial method for producing barium titanate high-frequency ceramic materials.

[0005] Therefore, how to improve the solid-phase sintering process, use the solid-phase sintering process for the large-scale industrial production of barium titanate high-frequency ceramic materials, and optimize the composition of barium titanate high-frequency ceramic materials to make them have high dielectric performance, low dielectric loss, and excellent temperature stability is a technical problem that urgently needs to be solved at present. Summary of the Invention

[0006] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a barium titanate high-frequency 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-frequency ceramic material to have good dielectric performance in a high-frequency environment; at the same time, it is also conducive to realizing industrialized scale production.

[0007] To achieve the object of the present invention, the following technical solutions are adopted in the present invention:

[0008] In a first aspect, the present invention provides a solid-phase sintering preparation method for a barium titanate high-frequency ceramic material, and the solid-phase sintering preparation method includes:

[0009] Mix barium titanate powder and additive powder, and the obtained mixed powder is sintered to obtain the barium titanate high-frequency ceramic material;

[0010] The preparation raw materials of the additive powder include BaCO3, Li2CO3 and Nb2O5 with a molar ratio of (7-9):1:(2-4);

[0011] The molar ratio of the barium titanate powder to the additive powder is 80:1-99:1. For example, it can be 80:1, 85:1, 90:1, 95:1 or 99:1, but is not limited to the listed values, and the other unlisted values within the numerical range are equally applicable.

[0012] The molar ratio of BaCO3 to Li2CO3 in the additive powder is (7-9):1. For example, it can be 7:1, 8:1 or 9:1, but is not limited to the listed values, and the other unlisted values within the numerical range are equally applicable.

[0013] The molar ratio of Li2CO3 to Nb2O5 in the additive powder is 1:(2-4). For example, it can be 1:2, 1:3 or 1:4, but is not limited to the listed values, and the other unlisted values within the numerical range are equally applicable.

[0014] The solid-phase sintering preparation method provided by the present invention can improve the dielectric properties of barium titanate ceramics in a high-frequency 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-frequency ceramic materials.

[0015] Preferably, 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, and the other unlisted values within the numerical range are equally applicable.

[0016] Preferably, 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, and the other unlisted values within the numerical range are equally applicable.

[0017] Preferably, the holding time at the highest temperature during the sintering treatment is 0.5 h - 3 h. For example, it can be 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h, or 3 h, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0018] Preferably, the additive powder is prepared by the following method: Mix BaCO3, Li2CO3, and Nb2O5 according to the formulated amounts, dry and decarbonize the mixture, and then perform additive crushing treatment to obtain the additive powder.

[0019] The solid-phase sintering preparation method provided by the present invention can make the particle size distribution of the obtained additive powder more concentrated by adopting a specific preparation method for the additive powder, so that the barium titanate high-frequency ceramic material has good dielectric properties in a high-frequency environment.

[0020] The additive powder used in the present invention specifically selects BaCO3, Li2CO3, and Nb2O5. When any one of the three additives is missing, the technical effect of improving the dielectric properties of barium titanate ceramics in a high-frequency environment cannot be achieved.

[0021] Among them, the use of BaCO3 provides the intrinsic property of high dielectric constant of the barium titanate ceramic material; the use of Li2CO3 realizes the substitution of Li for Ba, introduces lattice distortion, inhibits abnormal grain growth, refines grains, and thus reduces grain boundary polarization loss; the use of Nb2O5 can form a (Ba,Li)(Ti,Nb)O3 solid solution, inhibit grain coarsening at high temperatures, and reduce dielectric loss. Therefore, the synergy of BaCO3, Li2CO3, and Nb2O5 further improves the dielectric properties of the barium titanate ceramic material in a high-frequency environment.

[0022] Preferably, 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 6 h - 18 h (for example, it can be 6 h, 8 h, 10 h, 12 h, 15 h, 16 h, or 18 h, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable).

[0023] Preferably, the decarbonization 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 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. Other unlisted values within the numerical range are equally applicable).

[0024] Preferably, the barium titanate powder is prepared by the following method: Mix BaCO3 and TiO2 to obtain raw material powder; then perform pre-sintering treatment on the raw material powder to obtain a pre-sintered blank; the pre-sintered blank is successively subjected to a first crushing treatment, grinding, carbon removal treatment and a second crushing treatment to obtain the barium titanate powder.

[0025] In the solid-phase sintering preparation method provided by the present invention, by adopting a specific preparation method for the barium titanate powder, the median particle size distribution of the obtained barium titanate powder can be made more concentrated, so that the barium titanate high-frequency ceramic material has good dielectric properties in a high-frequency environment.

[0026] Among them, the pre-sintering treatment causes BaCO3 and TiO2 to undergo a solid-phase reaction 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 additive powder during subsequent sintering, so that the barium titanate high-frequency ceramic material has good dielectric properties in a high-frequency environment.

[0027] Preferably, the median particle sizes of the BaCO3 and the TiO2 are independently 3 μm - 15 μm, for example, they can be 3 μm, 5 μm, 8 μm, 10 μm, 12 μm or 15 μm, but are not limited to the listed values, and the other unlisted values within the numerical range are equally applicable.

[0028] Preferably, the molar ratio of the BaCO3 to the TiO2 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.

[0029] Preferably, 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.

[0030] In order to obtain a raw material powder with a median particle size D50 satisfying 0.8 μm - 3.5 μm, the mixing of BaCO3 and TiO2 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.

[0031] In the present invention, the starting temperature of the pre-sintering 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, etc.

[0032] Preferably, the heating rate of the pre-sintering 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.

[0033] Preferably, the maximum temperature of the pre-sintering 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.

[0034] Preferably, the holding time at the maximum temperature of the pre-sintering 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.

[0035] Preferably, the method of the first crushing treatment includes depolymerization.

[0036] Optionally, the depolymerization is carried out in a jet mill.

[0037] Preferably, 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.

[0038] In some embodiments, in order to obtain a powder with a median particle size D50 satisfying 0.8 μm - 3.5 μm by a jet mill and reduce the operating pressure of the jet mill, the first crushing treatment includes coarse crushing by a jaw crusher, fine crushing by a pair of rollers, and depolymerization by a 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.

[0039] Preferably, the method of the grinding includes sand grinding; the median particle size D50 of the powder obtained by the sand grinding is 0.6 μm - 1.5 μm. For example, it can be 0.6 μm, 0.9 μm, 1 μm, 1.2 μm or 1.5 μm, but is not limited to the listed values. The other unlisted values within the numerical range are equally applicable.

[0040] The present invention does not specifically limit parameters such as the sanding method and time. As long as the median particle size D50 of the powder obtained by sanding is 0.6 μm - 1.5 μm, generally speaking, controlling the sanding time to be 30 min - 180 min can achieve the technical effect that the median particle size D50 of the material obtained by sanding is 0.6 μm - 1.5 μm.

[0041] Grinding can further refine the particle size of barium titanate powder. During the continuous refinement of its particle size, the specific surface area increases, which is beneficial for obtaining a dense barium titanate high-frequency ceramic material in subsequent sintering. However, during the 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, it is necessary to perform carbon removal treatment after grinding to remove the dispersant.

[0042] 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.

[0043] Preferably, the carbon removal treatment includes: performing carbon removal at 450 °C - 800 °C for 8 h - 18 h.

[0044] 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.

[0045] 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.

[0046] In some embodiments, water is used as the sanding medium during sanding. Water has a good dispersion effect. During the sanding process, it adsorbs on the surface of solid particles, reducing the interfacial tension between liquid-liquid and solid-liquid, making the surface of the aggregated solid particles easy to wet, and preventing the mutual aggregation of fine particles. However, the residual moisture is not conducive to subsequent sintering.

[0047] 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.

[0048] The temperature of the drying 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, and the other unlisted values within the numerical range are equally applicable.

[0049] 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, and the other unlisted values within the numerical range are equally applicable.

[0050] In a second aspect, the present invention provides a barium titanate high-frequency ceramic material, which is prepared by the solid-phase sintering preparation method described in the first aspect.

[0051] In a third aspect, the present invention provides a high-frequency capacitor, which includes the barium titanate high-frequency ceramic material prepared by the solid-phase sintering preparation method described in the first aspect, or includes the barium titanate high-frequency ceramic material described in the second aspect.

[0052] The numerical range described in the present invention not only includes the above-listed point values, but also includes any point values between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the range.

[0053] Compared with the prior art, the present invention has the following beneficial effects:

[0054] The solid-phase sintering preparation method provided by the present invention can improve the dielectric properties of barium titanate ceramics in a high-frequency 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-frequency ceramic materials. Detailed Embodiments

[0055] The technical solutions 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 to the present invention.

[0056] For clearly illustrating the technical solutions of the present invention, the normal temperature in the following specific embodiments is 25°C.

[0057] Example 1

[0058] This example provides a solid-phase sintering preparation method for a barium titanate high-frequency ceramic material, and the solid-phase sintering preparation method includes:

[0059] (1) Prepare barium titanate powder:

[0060] S11: Weigh BaCO3 (median particle size D50 is 10μm) and TiO2 (median particle size D50 is 10μm) 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 jet mill to obtain raw material powder with a median particle size D50 of 2μm;

[0061] S12: The raw material powder is filled into the sagger, vibrated and compacted on a vibrating compactor to make the material fully dense, and then exhaust holes arranged in a uniform honeycomb pattern are punched out and placed in a muffle furnace for pre-sintering; when pre-sintering, the initial temperature is room temperature, the highest temperature is 1200 °C, the heating rate is 8 °C / min, and when the highest temperature is reached, heat preservation is carried out for 120 min to obtain a pre-sintered blank;

[0062] 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 pulverizer to obtain a powder with a median particle size D50 of 2 μm; then it is subjected to sand grinding treatment to reduce the median particle size D50 of the powder to 1 μm;

[0063] S14: The powder after sand grinding 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-roller machine to obtain barium titanate powder;

[0064] (2) Preparation of additive powder:

[0065] S21: Weigh BaCO3 (median particle size D50 is 10 μm), Li2CO3 (median particle size D50 is 10 μm), and Nb2O5 (median particle size D50 is 10 μm) according to a molar ratio of 8:1:3, and mix them evenly in a ball mill;

[0066] S22: The mixture 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-roller machine to obtain additive powder;

[0067] (3) Preparation of barium titanate high-frequency ceramic material

[0068] S31: The barium titanate powder obtained in step S14 and the additive powder obtained in step S24 are mixed in an air-flow pulverizer in a depolymerization manner according to a molar ratio of 90:1 to obtain a mixed raw material powder;

[0069] S32: The raw material powder is filled into the sagger, vibrated and compacted on a vibrating compactor to make the material fully dense, and then exhaust holes arranged in a uniform honeycomb pattern are punched out and placed in a muffle furnace for sintering treatment; when sintering, the initial temperature 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-frequency ceramic material.

[0070] Example 2

[0071] This example provides a solid-phase sintering preparation method for barium titanate high-frequency ceramic materials, and the solid-phase sintering preparation method includes:

[0072] (1) Preparation of barium titanate powder:

[0073] S11: Weigh BaCO3 (median particle size D50 is 3 μm) and TiO2 (median particle size D50 is 3 μm) according to the molar ratio of 0.990:1, conduct preliminary mixing in a three-dimensional mixer, and then crush and mix the mixed raw materials through an air-flow pulverizer to obtain raw material powder with a median particle size D50 of 0.8 μm;

[0074] S12: Load the raw material powder into a sagger, vibrate and compact it on a vibrating compactor to make the material fully dense, then punch out exhaust ports with a uniform honeycomb arrangement, and place it in 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, keep the temperature at the highest temperature for heat preservation, and the heat preservation time is 180 min to obtain a pre-sintered blank;

[0075] 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 an air-flow pulverizer to obtain powder with a median particle size D50 of 0.8 μm; then conduct sanding treatment to reduce the median particle size D50 of the powder to 0.6 μm;

[0076] S14: Dry the sanded powder at a temperature of 80 °C for 18 h, and then remove carbon at a temperature of 450 °C for 18 h; then conduct coarse crushing of the carbon-removed powder by a crusher and fine crushing by a pair-roll crusher to obtain barium titanate powder;

[0077] (2) Preparation of additive powder:

[0078] S21: Weigh BaCO3 (median particle size D50 is 3 μm), Li2CO3 (median particle size D50 is 3 μm) and Nb2O5 (median particle size D50 is 3 μm) according to the molar ratio of 7:1:4, and mix them evenly in a ball mill;

[0079] S22: Dry the mixture at a temperature of 80 °C for 18 h, and then remove carbon at a temperature of 450 °C for 18 h; then conduct coarse crushing of the carbon-removed powder by a crusher and fine crushing by a pair-roll crusher to obtain additive powder;

[0080] (3) Preparation of barium titanate high-frequency ceramic material

[0081] S31: Mix the barium titanate powder obtained in step S14 and the additive powder obtained in step S24 in an air-flow pulverizer in a depolymerization manner according to the molar ratio of 80:1 to obtain mixed raw material powder;

[0082] 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 arranged in a uniform honeycomb pattern are punched out, and it is put into 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 warm when the maximum temperature is reached, and the holding time is 3 h to obtain the barium titanate high-frequency ceramic material.

[0083] Example 3

[0084] This example provides a solid-phase sintering preparation method for a barium titanate high-frequency ceramic material, and the solid-phase sintering preparation method includes:

[0085] (1) Prepare barium titanate powder:

[0086] S11: Weigh BaCO3 (median particle size D50 is 15 μm) and TiO2 (median particle size D50 is 15 μm) according to a molar ratio of 1.010:1, perform preliminary mixing in a three-dimensional mixer, and then crush and mix the mixed raw materials with an air jet mill to obtain raw material powder with a median particle size D50 of 3.5 μm;

[0087] 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 holes arranged in a uniform honeycomb pattern are punched out, and it is put into 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, and it is kept warm when the maximum temperature is reached, and the holding time is 30 min to obtain a pre-sintered blank;

[0088] 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 jet mill to obtain powder with a median particle size D50 of 3.5 μm; then it is subjected to sanding treatment to reduce the median particle size D50 of the powder to 1.5 μm;

[0089] S14: The sanded powder is dried at 180 °C for 6 h, and then carbon is removed at 800 °C for 8 h; then the powder after carbon removal is subjected to coarse crushing by a crusher and fine crushing by a pair-roller machine to obtain barium titanate powder;

[0090] (2) Prepare additive powder:

[0091] S21: Weigh BaCO3 (median particle size D50 is 15 μm), Li2CO3 (median particle size D50 is 15 μm) and Nb2O5 (median particle size D50 is 15 μm) according to a molar ratio of 9:1:2, and mix them evenly in a ball mill;

[0092] S22: The mixture is dried at a temperature of 180 °C for 6 h, and then the carbon is removed at a temperature of 800 °C for 8 h; then the powder after carbon removal is roughly crushed by a crusher and finely crushed by a pair-roll crusher to obtain an additive powder;

[0093] (3) Preparation of barium titanate high-frequency ceramic material

[0094] S31: The barium titanate powder obtained in step S14 and the additive powder obtained in step S24 are mixed in a jet mill in a depolymerization manner according to a molar ratio of 99:1 to obtain a mixed raw material powder;

[0095] 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 arranged in a uniform honeycomb pattern are punched out, and then it is put into a muffle furnace for sintering treatment; the initial temperature during the sintering treatment is room temperature, the highest temperature is 1480 °C, the heating rate is 10 °C / min, and when the highest temperature is reached, heat preservation is carried out for 0.5 h to obtain the barium titanate high-frequency ceramic material.

[0096] Example 4

[0097] This example provides a solid-phase sintering preparation method of a barium titanate high-frequency ceramic material. Except that the carbon removal temperature in step S14 is 400 °C, the rest are the same as in Example 1.

[0098] Example 5

[0099] This example provides a solid-phase sintering preparation method of a barium titanate high-frequency ceramic material. Except that the carbon removal temperature in step S14 is 850 °C, the rest are the same as in Example 1.

[0100] Example 6

[0101] This example provides a solid-phase sintering preparation method of a barium titanate high-frequency ceramic material. Except that step S14 is not carried out, the rest are the same as in Example 1.

[0102] Example 7

[0103] This example provides a solid-phase sintering preparation method of a barium titanate high-frequency ceramic material. Except that the carbon removal temperature in step S22 is 400 °C, the rest are the same as in Example 1.

[0104] Example 8

[0105] This example provides a solid-phase sintering preparation method of a barium titanate high-frequency ceramic material. Except that the carbon removal temperature in step S22 is 850 °C, the rest are the same as in Example 1.

[0106] Example 9

[0107] This embodiment provides a solid-phase sintering preparation method for barium titanate high-frequency ceramic materials, which is the same as that of Embodiment 1 except that step S22 is not carried out.

[0108] Comparative Example 1

[0109] This comparative example provides a solid-phase sintering preparation method for barium titanate ceramic materials, which is the same as that of Embodiment 1 except that the sanding in step S13 is not carried out.

[0110] Comparative Example 2

[0111] This comparative example provides a solid-phase sintering preparation method for barium titanate ceramic materials, which is the same as that of Embodiment 1 except that the additive powder is BaCO3 and Li2CO3 with a molar ratio of 8:1.

[0112] Comparative Example 3

[0113] This comparative example provides a solid-phase sintering preparation method for barium titanate ceramic materials, which is the same as that of Embodiment 1 except that the additive powder is BaCO3 and Nb2O5 with a molar ratio of 8:3.

[0114] Comparative Example 4

[0115] This comparative example provides a solid-phase sintering preparation method for barium titanate ceramic materials, which is the same as that of Embodiment 1 except that the additive powder is Li2CO3 and Nb2O5 with a molar ratio of 1:3.

[0116] Comparative Example 5

[0117] This comparative example provides a solid-phase sintering preparation method for barium titanate ceramic materials, which is the same as that of Embodiment 1 except that the additive powder is only BaCO3.

[0118] Comparative Example 6

[0119] This comparative example provides a solid-phase sintering preparation method for barium titanate ceramic materials, which is the same as that of Embodiment 1 except that the additive powder is only Li2CO3.

[0120] Comparative Example 7

[0121] This comparative example provides a solid-phase sintering preparation method for barium titanate ceramic materials, which is the same as that of Embodiment 1 except that the additive powder is only Nb2O5.

[0122] Performance Characterization

[0123] 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 to obtain the dielectric constant ε r (F / m) and dielectric loss tanδ. The obtained results are shown in Table 1.

[0124] Table 1

[0125]

[0126] In summary, the solid-phase sintering preparation method provided by the invention can improve the dielectric properties of barium titanate ceramics in a high-frequency environment 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-frequency ceramic materials; moreover, in the solid-phase sintering preparation method provided by the invention, the barium titanate powder and the additive powder are respectively dried, carbon-discharged, and crushed, so that the median particle size distribution of the raw materials is improved, thereby improving the dielectric properties of barium titanate ceramics in a high-frequency environment.

[0127] 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 thought of by any person 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-frequency ceramic material, characterized in that, The solid-phase sintering preparation method includes: Mixing barium titanate powder and additive powder, and subjecting the obtained mixed powder to sintering treatment to obtain the barium titanate high-frequency ceramic material; The preparation raw materials of the additive powder include BaCO3, Li2CO3 and Nb2O5 with a molar ratio of (7-9):1:(2-4); The molar ratio of the barium titanate powder to the additive powder is 80:1 - 99:

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 0.5 h - 3 h.

3. The solid-phase sintering preparation method according to claim 1, wherein The additive powder is prepared by the following preparation method: Mix BaCO3, Li2CO3 and Nb2O5 according to the formula amount, dry and degasify the mixture, and then perform additive crushing treatment to obtain the additive powder.

4. The solid-phase sintering preparation method according to claim 3, wherein The temperature of the drying is 80°C - 180°C, and the time is 6 h - 18 h; And / or, the temperature of the degassing is 450°C - 800°C, and the time is 8 h - 18 h.

5. The solid-phase sintering preparation method according to claim 1, characterized in that The barium titanate powder is prepared by the following preparation method: Mix BaCO3 and TiO2 to obtain raw material powder; then perform pre-sintering treatment on the raw material powder to obtain a pre-sintered blank; the pre-sintered blank is successively subjected to first crushing treatment, grinding, degassing treatment and second crushing treatment to obtain the barium titanate powder.

6. The solid-phase sintering preparation method according to claim 5, characterized in that, The median particle sizes of the BaCO3 and the TiO2 are independently 3 μm - 15 μm; And / or, the molar ratio of the BaCO3 to the TiO2 is 0.990:1 - 1.010:1; And / or, the median particle size D50 of the raw material powder is 0.8 μm - 3.5 μm.

7. The solid-phase sintering preparation method according to claim 5, 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 30 min - 180 min; 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 0.8 μm - 3.5 μm.

8. The solid-phase sintering preparation method according to claim 5, 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 0.6 μm - 1.5 μm. And / or, the degassing treatment includes: degassing at 450°C - 800°C for 8 h - 18 h; And / or, the degassing treatment further includes drying before degassing: drying at a temperature of 80°C - 180°C for 6 h - 18 h.

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

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

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