Barium titanate-based ceramic material with high dielectric constant as well as solid-phase sintering preparation method and application of barium titanate-based ceramic material

Abstract

The invention relates to a high-dielectric-constant barium titanate-based ceramic material and 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 carrying out sintering treatment on the obtained mixed powder to obtain the high-dielectric-constant barium titanate-based ceramic material, the auxiliary material powder is prepared from the following raw materials: Mn3O4, Dy2 (CO3) 3 and CaCO3 in a molar ratio of (1.5-2.5): 1: (1-2); the molar ratio of the barium titanate powder to the auxiliary material powder is (10: 1)-(25: 1). According to the solid-phase sintering preparation method provided by the invention, the dielectric constant and the temperature stability of the barium titanate-based ceramic material 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-based ceramic material with the high dielectric constant.

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-based ceramic material with a high dielectric constant, a solid-phase sintering preparation method thereof, and an application thereof. Background Art

[0002] In recent years, due to its unique ferroelectricity and high dielectric constant, barium titanate has become an ideal choice for high-frequency and high-capacitance miniature capacitors and is widely used in modern electronic circuits. The dielectric coefficient of traditional BaTiO3 ceramics at the Curie point is between 6000 and 10000, and there are deficiencies in terms of thermal stability; in addition, the higher the dielectric coefficient of BaTiO3 ceramics, the greater the dielectric loss, which directly affects the service life, stability, and safety of ceramic capacitors using barium titanate as a raw material.

[0003] In the prior art, materials such as Mg2TiO4, CaSrO3, and SrZrO3 are usually added to adjust its temperature stability. However, the dielectric constants of these materials themselves are only 15 to 30. Therefore, it is difficult to obtain a BaTiO3 high-frequency ceramic material with a large dielectric constant and high temperature stability. Therefore, the present invention needs to modify the BaTiO3-based ceramics to make them have a high dielectric constant, low dielectric loss, and excellent temperature stability, so that they can better adapt to the working environment in electronic circuits.

[0004] At present, most domestic industrial production of modified BaTiO3 ceramic materials uses the liquid-phase synthesis method. In the process of liquid-phase synthesis, the raw material cost is high and the processing technology is complex. The required pressure and temperature are relatively high, resulting in a high investment and construction scale cost; at the same time, a large amount of wastewater needs to be discharged during the liquid-phase 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. At present, there is no complete, systematic, and large-scale solid-phase sintering production line in China for producing modified BaTiO3-based ceramic powder materials.

[0005] Therefore, how to realize the industrialization of the preparation of modified barium titanate-based ceramic materials with a high dielectric constant by the solid-phase sintering method 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-based ceramic material with a high dielectric constant, a solid-phase sintering preparation method thereof, and an application thereof. The solid-phase sintering preparation method can enable the barium titanate-based ceramic material with a high dielectric constant to have a relatively high dielectric constant and relatively high temperature stability, and at the same time is 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 high-dielectric-constant barium titanate-based ceramic material, and the solid-phase sintering preparation method includes:

[0009] Mix barium titanate powder with auxiliary material powder, and the obtained mixed powder is sintered to obtain the high-dielectric-constant barium titanate-based ceramic material;

[0010] The preparation raw materials of the auxiliary material powder include Mn3O4, Dy2(CO3)3 and CaCO3 with a molar ratio of (1.5 - 2.5):1:(1 - 2);

[0011] The molar ratio of the barium titanate powder to the auxiliary material powder is 10:1 to 25:1.

[0012] The solid-phase sintering preparation method provided by the present invention can improve the dielectric constant and temperature stability of the barium titanate-based ceramic material 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 the high-dielectric-constant barium titanate-based ceramic material.

[0013] Preferably, the heating rate of the sintering treatment is 2°C / min to 10°C / min.

[0014] Preferably, the highest temperature of the sintering treatment is 1200°C to 1480°C.

[0015] Preferably, the heat preservation time at the highest temperature of the sintering treatment is 0.5 h to 3 h.

[0016] Preferably, the preparation method of the auxiliary material powder includes: mixing Mn3O4, Dy2(CO3)3 and CaCO3 according to the formula amount, drying and decarbonizing the mixed powder, and then performing auxiliary material crushing treatment to obtain the auxiliary material powder.

[0017] Preferably, the drying temperature is 80°C to 180°C, and the time is 6 h to 18 h.

[0018] Preferably, the decarbonizing temperature is 450°C to 800°C, and the time is 8 h to 18 h.

[0019] Preferably, the preparation method of the barium titanate powder includes: mixing a barium source and a titanium source to obtain raw material powder; then performing pre-sintering treatment on the raw material powder to obtain a pre-sintered blank; and performing first crushing, grinding, decarbonizing treatment and second crushing on the pre-sintered blank in sequence to obtain the barium titanate powder.

[0020] Preferably, the median particle sizes of the barium source and the titanium source are independently 3 μm to 15 μm.

[0021] Preferably, the molar ratio of Ba in the barium source to Ti in the titanium source is 1:0.85 to 1:1.25.

[0022] Preferably, the median particle size D50 of the raw material powder is 0.8 μm to 3.5 μm.

[0023] Preferably, the heating rate of the pre-sintering is 5 °C / min to 10 °C / min.

[0024] Preferably, the highest temperature of the pre-sintering is 1150 °C to 1350 °C.

[0025] Preferably, the holding time at the highest temperature of the pre-sintering is 30 min to 180 min.

[0026] Preferably, the method of the first crushing includes depolymerization.

[0027] Preferably, the median particle size D50 of the powder after the first crushing is 0.8 μm to 3.5 μm.

[0028] 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 to 1.5 μm.

[0029] Preferably, the carbon removal treatment includes: performing carbon removal at 450 °C to 800 °C for 8 h to 18 h.

[0030] Preferably, the carbon removal treatment further includes drying before carbon removal: drying at a temperature of 80 °C to 180 °C for 6 h to 18 h.

[0031] In a second aspect, the present invention provides a high dielectric constant barium titanate-based ceramic material, and the high dielectric constant barium titanate-based ceramic material 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-temperature capacitor, and the high-temperature capacitor includes the high dielectric constant barium titanate-based ceramic material prepared by the solid-phase sintering preparation method described in the first aspect, or includes the high dielectric constant barium titanate-based ceramic material described in the second aspect.

[0033] The numerical ranges described in the present invention not only include the 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 ranges.

[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-temperature resistance of barium titanate ceramics 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 high-dielectric-constant barium titanate-based ceramic materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 SEM diagram of the high-dielectric-constant barium titanate-based ceramic material obtained in Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0037] 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 on the present invention.

[0038] An embodiment of the present invention provides a solid-phase sintering preparation method of a high-dielectric-constant barium titanate-based ceramic material, and the solid-phase sintering preparation method includes:

[0039] Mix barium titanate powder with auxiliary material powder, and the obtained mixed powder is sintered to obtain the high-dielectric-constant barium titanate-based ceramic material;

[0040] The preparation raw materials of the auxiliary material powder include Mn3O4, Dy2(CO3)3 and CaCO3 with a molar ratio of (1.5 - 2.5):1:(1 - 2).

[0041] The molar ratio of the barium titanate powder to the auxiliary material powder is 10:1 - 25:1. For example, it can be 10:1, 12:1, 15:1, 20:1 or 25:1, but is not limited to the listed values, and the other unlisted values within the numerical range are equally applicable.

[0042] The molar ratio of Mn3O4 to Dy2(CO3)3 in the auxiliary material powder is (1.5 - 2.5):1. For example, it can be 1.5:1, 2:1 or 2.5:1, but is not limited to the listed values, and the other unlisted values within the numerical range are equally applicable.

[0043] The molar ratio of Dy2(CO3)3 to CaCO3 in the auxiliary material powder is 1:(1 - 2). For example, it can be 1:1, 1:1.5 or 1:2, but is not limited to the listed values, and the other unlisted values within the numerical range are equally applicable.

[0044] The solid-phase sintering preparation method provided by the present invention can improve the dielectric constant and temperature stability of barium titanate-based ceramic materials 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 high-dielectric-constant barium titanate-based ceramic materials.

[0045] The present invention uses CaCO3 in the auxiliary materials, and the Ca therein 2+ can partially replace Ba in the BaTiO3 lattice 2+ , which is beneficial to obtaining a higher dielectric constant of barium titanate powder at room temperature; however, when using CaCO3 according to the conventional addition method in the prior art, lattice distortion is likely to occur. The present invention controls the components in the auxiliary material powder and improves the preparation method, so that the role of Ca can be exerted without the cooperation of CaCO3 and additional metal oxides, and the occurrence of lattice distortion can be avoided. 2+

[0046] In some embodiments, the heating rate of the sintering treatment is 2 °C / min to 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.

[0047] In some embodiments, the highest temperature of the sintering treatment is 1200 °C to 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.

[0048] In some embodiments, the holding time at the highest temperature of the sintering treatment is 0.5 h to 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, and the other unlisted values within the numerical range are equally applicable.

[0049] In some embodiments, the method for preparing the auxiliary material powder includes: mixing Mn3O4, Dy2(CO3)3 and CaCO3 according to the formula amount, drying and decarbonizing the mixed powder, and then performing auxiliary material crushing treatment to obtain the auxiliary material powder.

[0050] 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 high-dielectric-constant barium titanate-based ceramic material has good temperature stability.

[0051] The auxiliary material powder used in the present invention specifically selects specific proportions of Mn3O4, Dy2(CO3)3 and CaCO3. When any one of the three auxiliary materials is missing, the function of improving the dielectric constant and temperature stability of the barium titanate-based ceramic material cannot be exerted.

[0052] Mn3O4 in the auxiliary material powder decomposes into Mn 2+ and Mn​3+ , can replace Ti 4+ , suppress the free carrier concentration, thereby reducing the leakage current and dielectric loss; Dy3+ in Dy2(CO3)3 + can replace Ba 2+ and introduce oxygen vacancies, broaden the temperature response platform of the dielectric constant, and reduce the dielectric loss caused by grain boundary diffusion; Ca in CaCO3 2+ can partially replace Ba 2+ , which is beneficial to obtaining a higher dielectric constant for barium titanate powder at room temperature. Moreover, the small-size shrinkage effect of Ca 2+ and the large-size expansion effect of Dy 3+ offset each other, maintaining the structural stability of the barium titanate-based ceramic material; and the oxygen vacancies introduced by Dy 3+ and the synergistic cooperation of Mn 2+ , Mn 3+ can reduce the dielectric loss, enabling the barium titanate-based ceramic material to maintain a high value within a wide temperature range.

[0053] In some embodiments, the temperature of the drying is 80°C to 180°C (for example, it can be 80°C, 100°C, 120°C, 150°C, 160°C or 180°C, but not limited to the listed values), and the time is 6h to 18h (for example, it can be 6h, 8h, 10h, 12h, 15h, 16h or 18h, but not limited to the listed values).

[0054] In some embodiments, the temperature of the carbon removal is 450°C to 800°C (for example, it can be 450°C, 500°C, 600°C, 700°C or 800°C, but not limited to the listed values), and the time is 8h to 18h (for example, it can be 8h, 10h, 12h, 15h, 16h or 18h, but not limited to the listed values).

[0055] In some embodiments, the method for preparing the barium titanate powder includes: 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 first crushing, grinding, carbon removal treatment and second crushing on the pre-sintered blank to obtain the barium titanate powder.

[0056] 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-based ceramic material with a high dielectric constant has a high dielectric constant and temperature stability.

[0057] Among them, the pre-sintering treatment causes the titanium source and the barium source 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 auxiliary powder during subsequent sintering, thereby improving the dielectric constant and temperature stability of the barium titanate-based ceramic material.

[0058] In some embodiments, the barium source includes barium carbonate and / or barium oxide.

[0059] In some embodiments, the titanium source includes titanium dioxide.

[0060] In some embodiments, the median particle sizes of the barium source and the titanium source are independently 3 μm to 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.

[0061] In some embodiments, the molar ratio of Ba in the barium source to Ti in the titanium source is 1:0.85 to 1:1.25. For example, it can be 1:0.85, 1:0.9, 1:1, 1:1.1, or 1:1.25, but is not limited to the listed values, and the other unlisted values within the numerical range are equally applicable.

[0062] In some embodiments, the median particle size D50 of the raw material powder is 0.8 μm to 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.

[0063] In order to obtain a raw material powder with a median particle size D50 satisfying 0.8 μm to 3.5 μm, the barium source and the titanium source are first mixed in a three-dimensional mixer, and then a jet mill is used to obtain a raw material powder with a median particle size D50 satisfying 0.8 μm to 3.5 μm.

[0064] In some embodiments, the heating rate of the pre-sintering is 5 °C / min to 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, and the other unlisted values within the numerical range are equally applicable.

[0065] In the present invention, the starting temperature of the pre-sintering is room temperature. For example, it can be 15 °C to 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, and the other unlisted values within the numerical range are equally applicable.

[0066] In some embodiments, the maximum temperature of the pre-sintering is 1150°C to 1350°C, but is not limited to the listed values, and the other unlisted values within the numerical range are equally applicable.

[0067] In some embodiments, the heat preservation time of the pre-sintering at the maximum 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, and the other unlisted values within the numerical range are equally applicable.

[0068] In some embodiments, the method of the first crushing includes depolymerization.

[0069] Exemplarily, the depolymerization is carried out in a jet mill.

[0070] In some embodiments, the median particle size D50 of the powder after the first crushing is 0.8 μm to 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.

[0071] In some embodiments, in order to obtain a powder with a median particle size D50 satisfying 0.8 μm to 3.5 μm by a jet mill and reduce the operating pressure of the jet mill, the first crushing includes sequentially performing coarse crushing by a jaw crusher, fine crushing by a roll crusher, and depolymerization by a jet mill. 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 greater than that of the material obtained by fine crushing.

[0072] In some embodiments, 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 to 1.5 μm, etc.

[0073] The present invention does not specifically limit parameters such as the method and time of the sand grinding, as long as the median particle size D50 of the powder obtained by the sand grinding is 0.6 μm to 1.5 μm. Generally speaking, controlling the sand grinding time to be 30 min to 180 min can achieve the technical effect that the median particle size D50 of the material obtained by the sand grinding is 0.6 μm to 1.5 μm.

[0074] 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 high-dielectric-constant barium titanate-based 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 forces, double-layer electrostatic interactions, etc. Therefore, as a preferred technical solution, a dispersant is used during grinding to prevent the mutual aggregation of barium titanate powder. Therefore, carbon removal treatment is required after grinding to remove the dispersant.

[0075] 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.

[0076] In some embodiments, the carbon removal treatment includes: performing carbon removal at 450°C to 800°C for 8h to 18h.

[0077] 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.

[0078] The time of the carbon removal is 8h to 18h. For example, it can be 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.

[0079] In some embodiments, water is used as the sanding medium in the 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 agglomerated solid particles easy to wet, and preventing the mutual aggregation of fine particles. However, the residual moisture is not conducive to subsequent sintering.

[0080] Preferably, the carbon removal treatment further includes drying before carbon removal: drying at a temperature of 80°C to 180°C for 6h to 18h.

[0081] The temperature of the drying is 80°C to 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.

[0082] The time of the drying is 6h to 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.

[0083] An embodiment of the present invention provides a high dielectric constant barium titanate-based ceramic material, and the high dielectric constant barium titanate-based ceramic material is prepared by the solid-phase sintering preparation method described in any embodiment.

[0084] The present invention provides a high-temperature capacitor, and the high-temperature capacitor includes the high dielectric constant barium titanate-based ceramic material prepared by the solid-phase sintering preparation method described in any embodiment, or includes the high dielectric constant barium titanate-based ceramic material described in any embodiment.

[0085] In order to clearly illustrate the technical solution of the present invention, the normal temperature in the following specific embodiments is 25°C.

[0086] Example 1

[0087] This embodiment provides a solid-phase sintering preparation method for a high dielectric constant barium titanate-based ceramic material, and the solid-phase sintering preparation method includes:

[0088] (1) Prepare barium titanate powder:

[0089] 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;

[0090] S12: Put 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 with a uniform honeycomb arrangement, 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;

[0091] 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;

[0092] 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 carbon-removed powder by a crusher and fine crushing by a pair-roller machine to obtain barium titanate powder;

[0093] (2) Prepare auxiliary material powder:

[0094] S21: Weigh Mn3O4 (median particle size D50 is 10 μm), Dy2(CO3)3 (median particle size D50 is 10 μm) and CaCO3 (median particle size D50 is 10 μm) according to the molar ratio of 2:1:1.5, and mix them evenly in a ball mill;

[0095] S22: Dry the evenly mixed powder at 150 °C for 10 h, and then remove carbon at 600 °C for 12 h; then coarsely crush the powder after carbon removal with a crusher and finely crush it with a pair-roll mill to obtain auxiliary material powder;

[0096] (3) Prepare high dielectric constant barium titanate-based ceramic material

[0097] 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 way of depolymerization according to the molar ratio of 20:1 to obtain mixed raw material powder;

[0098] S32: 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 holes with a uniform honeycomb arrangement, and put it 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, keep the temperature at the highest temperature for insulation, and the insulation time is 2 h to obtain the high dielectric constant barium titanate-based ceramic material.

[0099] The high dielectric constant barium titanate-based ceramic material obtained in this embodiment is successively coarsely crushed by a jaw crusher, finely crushed by a pair-roll mill and depolymerized by a jet mill to obtain barium titanate ceramic particles with a median particle size D50 of 1 μm, and its SEM image is as Figure 1 shown.

[0100] Example 2

[0101] This embodiment provides a solid-phase sintering preparation method of a high dielectric constant barium titanate-based ceramic material, and the solid-phase sintering preparation method includes:

[0102] (1) Prepare barium titanate powder:

[0103] S11: Weigh barium carbonate (median particle size D50 is 3 μm) and titanium dioxide (median particle size D50 is 3 μm) according to the molar ratio of 1:0.85, conduct preliminary mixing in a three-dimensional mixer, and then crush and mix the mixed raw materials with a jet mill to obtain raw material powder with a median particle size D50 of,

[0104] S12: The raw material powder is filled into a sagger, vibrated and compacted on a vibrating compactor to make the material fully dense, 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 1150 °C, the heating rate is 5 °C / min, and it is kept at the maximum temperature for heat preservation for 180 min to obtain a pre-sintered blank;

[0105] 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 0.8 μm; then it is subjected to sanding treatment to reduce the median particle size D50 of the powder to 0.6 μm;

[0106] S14: The sanded powder is dried at 80 °C for 18 h, and then carbon is removed at 450 °C for 18 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;

[0107] (2) Preparation of auxiliary material powder:

[0108] S21: Weigh Mn3O4 (median particle size D50 is 3 μm), Dy2(CO3)3 (median particle size D50 is 3 μm) and CaCO3 (median particle size D50 is 3 μm) according to the molar ratio of 1.5:1:2, and mix them evenly in a ball mill;

[0109] S22: The evenly mixed powder is dried at 80 °C for 18 h, and then carbon is removed at 450 °C for 18 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 auxiliary material powder;

[0110] (3) Preparation of high dielectric constant barium titanate-based ceramic material

[0111] 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 the molar ratio of 10:1 to obtain a mixed raw material powder;

[0112] S32: The raw material powder is filled into a sagger, vibrated and compacted on a vibrating compactor to make the material fully dense, 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 at the maximum temperature for heat preservation for 3 h to obtain the high dielectric constant barium titanate-based ceramic material.

[0113] Example 3

[0114] This example provides a solid-phase sintering preparation method for a high dielectric constant barium titanate-based ceramic material, and the solid-phase sintering preparation method includes:

[0115] (1) Preparation of barium titanate powder:

[0116] S11: Weigh barium carbonate (median particle size D50 is 15 μm) and titanium dioxide (median particle size D50 is 15 μm) according to a molar ratio of 1:1.25, 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 3.5 μm;

[0117] 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 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 1350 °C, the heating rate is 10 °C / min, keep the temperature at the highest temperature for heat preservation, and the heat preservation time is 30 min to obtain a pre-sintered blank;

[0118] 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 powder with a median particle size D50 of 3.5 μm; then conduct sanding treatment to reduce the median particle size D50 of the powder to 1.5 μm;

[0119] 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 conduct coarse crushing of the powder after carbon removal by a crusher and fine crushing by a pair-roller machine to obtain barium titanate powder;

[0120] (2) Preparation of auxiliary material powder:

[0121] S21: Weigh Mn3O4 (median particle size D50 is 15 μm), Dy2(CO3)3 (median particle size D50 is 15 μm) and CaCO3 (median particle size D50 is 15 μm) according to a molar ratio of 2.5:1:1, and mix them evenly in a ball mill;

[0122] 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 conduct coarse crushing of the powder after carbon removal by a crusher and fine crushing by a pair-roller machine to obtain auxiliary material powder;

[0123] (3) Preparation of high dielectric constant barium titanate-based ceramic materials

[0124] S31: Mix the barium titanate powder obtained in step S14 and the auxiliary material powder obtained in step S24 in an air-flow pulverizer in a depolymerization manner according to a molar ratio of 25:1 to obtain mixed raw material powder;

[0125] S32: The raw material powder is filled into a crucible and vibrated on a vibrotable to make the material fully dense. Then, exhaust holes arranged in a uniform honeycomb pattern are punched out, and it is placed in a muffle furnace for sintering treatment. During the sintering treatment, the initial temperature is room temperature, the maximum temperature is 1480 °C, and the heating rate is 10 °C / min. When the maximum temperature is reached, heat preservation is carried out for 0.5 h to obtain the high dielectric constant barium titanate-based ceramic material.

[0126] Example 4

[0127] This example provides a solid-phase sintering preparation method for a high dielectric constant barium titanate-based ceramic material. Except that the carbon removal temperature in step S14 is 400 °C, the rest are the same as in Example 1.

[0128] Example 5

[0129] This example provides a solid-phase sintering preparation method for a high dielectric constant barium titanate-based ceramic material. Except that the carbon removal temperature in step S14 is 850 °C, the rest are the same as in Example 1.

[0130] Example 6

[0131] This example provides a solid-phase sintering preparation method for a high dielectric constant barium titanate-based ceramic material. Except that step S14 is not carried out, the rest are the same as in Example 1.

[0132] Example 7

[0133] This example provides a solid-phase sintering preparation method for a high dielectric constant barium titanate-based ceramic material. Except that the carbon removal temperature in step S22 is 400 °C, the rest are the same as in Example 1.

[0134] Example 8

[0135] This example provides a solid-phase sintering preparation method for a high dielectric constant barium titanate-based ceramic material. Except that the carbon removal temperature in step S22 is 850 °C, the rest are the same as in Example 1.

[0136] Example 9

[0137] This example provides a solid-phase sintering preparation method for a high dielectric constant barium titanate-based ceramic material. Except that step S22 is not carried out, the rest are the same as in Example 1.

[0138] Comparative Example 1

[0139] This comparative example provides a solid-phase sintering preparation method for a barium titanate-based ceramic material. Except that the sanding in step S13 is not carried out, the rest are the same as in Example 1.

[0140] Comparative Example 2

[0141] This comparative example provides a solid-phase sintering preparation method for barium titanate-based ceramic materials. Except that the raw materials for preparing the auxiliary material powder are Mn3O4 and Dy2(CO3)3 with a molar ratio of 2:1, the rest are the same as in Example 1.

[0142] Comparative Example 3

[0143] This comparative example provides a solid-phase sintering preparation method for barium titanate-based ceramic materials. Except that the auxiliary material powder is Mn3O4 and CaCO3 with a molar ratio of 2:1.5, the rest are the same as in Example 1.

[0144] Comparative Example 4

[0145] This comparative example provides a solid-phase sintering preparation method for barium titanate-based ceramic materials. Except that the auxiliary material powder is Dy2(CO3)3 and CaCO3 with a molar ratio of 1:2, the rest are the same as in Example 1.

[0146] Comparative Example 5

[0147] This comparative example provides a solid-phase sintering preparation method for barium titanate-based ceramic materials. Except that the auxiliary material powder is only Mn3O4, the rest are the same as in Example 1.

[0148] Comparative Example 6

[0149] This comparative example provides a solid-phase sintering preparation method for barium titanate-based ceramic materials. Except that the auxiliary material powder is only Dy2(CO3)3, the rest are the same as in Example 1.

[0150] Comparative Example 7

[0151] This comparative example provides a solid-phase sintering preparation method for barium titanate-based ceramic materials. Except that the auxiliary material powder is only CaCO3, the rest are the same as in Example 1.

[0152] Performance Characterization

[0153] The barium titanate ceramic materials obtained in the above examples and comparative examples were successively coarsely crushed by a jaw crusher, finely crushed by a pair-roll crusher, and depolymerized by a 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, and the dielectric properties of the disc samples were tested in the temperature range of -55 °C to 125 °C (dielectric constant ε r (F / m) and dielectric loss tanδ). The obtained results are shown in Tables 1 and 2, where the temperature-capacitance change rate is the absolute value of the measured results.

[0154] Table 1

[0155]

[0156]

[0157] Table 2

[0158] Temperature change rate Example 1 12.6％ Example 2 14.3％ Example 3 13.5％ Example 4 13.6％ Example 5 11.7％ Example 6 14.9％ Example 7 12.8％ Example 8 12.5％ Example 9 11.1％ Comparative Example 1 19.6％ Comparative Example 2 22.3％ Comparative Example 3 21.4％ Comparative Example 4 26.4％ Comparative Example 5 23.2％ Comparative Example 6 21.0％ Comparative Example 7 19.6％

[0159] In summary, the solid-phase sintering preparation method provided by the present invention can improve the dielectric constant and temperature stability of barium titanate-based ceramic materials 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-based ceramic materials with high dielectric constant.

[0160] 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 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-based ceramic material with high dielectric constant, 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 high-dielectric-constant barium titanate-based ceramic material; The raw materials for preparing the auxiliary material powder include Mn3O4, Dy2(CO3)3, and CaCO3 with a molar ratio of (1.5 to 2.5):1:(1 to 2); The molar ratio of the barium titanate powder to the auxiliary material powder is 10:1 to 25:

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 to 10 °C / min; And / or, the highest temperature of the sintering treatment is 1200 °C to 1480 °C; And / or, the holding time at the highest temperature of the sintering treatment is 0.5 h to 3 h.

3. The solid-phase sintering preparation method according to claim 1, wherein The method for preparing the auxiliary material powder includes: mixing Mn3O4, Dy2(CO3)3, and CaCO3 according to the formula amount, drying and decarbonizing the mixed powder, and then performing auxiliary material crushing treatment to obtain the auxiliary material powder.

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

5. The solid-phase sintering preparation method according to claim 1, wherein The method for preparing the barium titanate powder includes: 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 first crushing, grinding, decarbonization treatment, and second crushing on the pre-sintered blank to obtain the barium titanate powder.

6. The solid-phase sintering preparation method according to claim 5, wherein The median particle sizes of the barium source and the titanium source are independently 3 μm - 15 μm; And / or, the molar ratio of Ba in the barium source to Ti in the titanium source is 1:0.85 to 1:1.25; 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 to 10 °C / min; And / or, the highest temperature of the pre-sintering is 1150 °C to 1350 °C; And / or, the holding time at the highest temperature of the pre-sintering is 30 min to 180 min; And / or, the method of the first crushing includes deflocculation; And / or, the median particle size D50 of the powder after the first crushing 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 sanding; the median particle size D50 of the powder obtained by sanding is 0.6 μm to 1.5 μm. And / or, the decarbonization treatment includes: performing decarbonization at 450 °C to 800 °C for 8 h to 18 h; And / or, the decarbonization treatment further includes drying before decarbonization: drying at a temperature of 80 °C to 180 °C for 6 h to 18 h.

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

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

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