Wafer type barium titanate ceramic capacitor dielectric material and preparation method and application thereof

Abstract

The invention relates to a wafer-type barium titanate ceramic capacitor dielectric material and a preparation method and application thereof, and the preparation method comprises the steps: uniformly mixing barium titanate-based mixed powder and stearate, pressing, and sintering to obtain the wafer-type barium titanate ceramic capacitor dielectric material, the raw materials of the barium titanate-based mixed powder comprise barium titanate, rare earth oxide and a silica sol solution. The stearate is used as an internal release agent to solve the problem of large release resistance in the subsequent pressing process due to the fact that silica sol liquid is used for replacing an organic binder to produce the wafer ceramic, and is also used as a doping source, and metal carbonate obtained in the subsequent heat treatment process is firstly filled in gaps of barium titanate particles to reduce the internal porosity of a green body; gaps of barium titanate particles are further filled with trace high-activity metal oxide obtained through further heat treatment, the surfaces of the barium titanate particles are wrapped with a vitreous liquid phase formed by silicon dioxide, then the dielectric constant is increased, the performance stability is improved, and the yield is remarkably increased.

Description

Technical Field

[0001] This invention relates to the field of ceramic capacitor dielectric material preparation technology, and in particular to a disc-type barium titanate ceramic capacitor dielectric material, its preparation method, and its application. Background Technology

[0002] Disc ceramic capacitors are small, compact, high-precision electronic components with excellent frequency response. They typically possess characteristics such as high dielectric constant, low loss, good temperature stability and withstand voltage, and fast response time. These features make disc ceramic capacitors widely used in various electronic devices and indispensable components in many circuit designs. Among them, barium titanate (BaTiO3) as the main material is one of the most widely used ceramic materials and occupies a core position.

[0003] CN117185803A discloses an ultra-low temperature sintering X7R dielectric material and its preparation method. The preparation method includes weighing and mixing BaTiO3, a modifier, and a cooling agent in a certain proportion, adding paraffin wax, granulating, pressing into discs, and then sintering. CN109485409A discloses a non-aqueous casting method for barium titanate sheet ceramics, including mixing barium titanate powder with a solvent, a dispersant, a binder, polyvinyl butyral (PVB), and a plasticizer, followed by post-treatment to obtain sheet ceramics. CN117585998A discloses a preparation method for high-performance bismuth ferrite barium titanate-based lead-free high-temperature piezoelectric ceramics, including preparing BF-BT powder and BCZT powder, mixing the two to obtain a solid solution powder, adding 3wt%~7wt% polyvinyl alcohol (PVA) solution for granulation, pressing into discs, and sintering to obtain a large strain piezoelectric ceramic material.

[0004] It is evident that existing technologies for preparing barium titanate-based ceramic dielectric materials typically incorporate PVB, PVA, or paraffin as binders for granulation. Furthermore, the addition of these binders necessitates low-temperature debinding, significantly increasing sintering time and hindering production efficiency. Incomplete debinding also results in residual carbon materials from decomposition remaining in the material, reducing its density and consequently lowering product performance. Additionally, to obtain high dielectric constant disc ceramic capacitor dielectric materials, additives such as silica, lithium carbonate, or boron oxide are often added to lower the sintering temperature and prevent abnormal grain growth caused by high temperatures.

[0005] Based on this, the study found that the silica sol solution contains a certain amount of silica and also has a certain viscosity. Therefore, it can replace traditional organic binders such as PVB, PVA or paraffin and traditional powdered silica additives in the reaction system. This can greatly reduce the glue removal time during the sintering process, and while lowering the sintering temperature of barium titanate ceramic materials, it can further improve the density of the dielectric material of disc ceramic capacitors and reduce the formation of pores.

[0006] However, when using silica sol liquid, the resistance during demolding after pressing is large, which significantly increases the damage rate and defect rate of the dielectric material of the resulting disc ceramic capacitor. If an external release agent is sprayed to facilitate demolding after pressing the ceramic disc, although the damage rate and defect rate can be reduced and demolding can be easier, the residual external release agent can easily affect the density stability and dielectric properties of the ceramic.

[0007] Therefore, how to solve the problem of high damage and defect rates caused by large demolding resistance when using silica sol to prepare disc barium titanate ceramic capacitor dielectric materials, and how to further improve the performance of disc barium titanate ceramic capacitor dielectric materials, has become an urgent problem to be solved. Summary of the Invention

[0008] To address the aforementioned technical problems, this invention provides a disc-type barium titanate ceramic capacitor dielectric material, its preparation method, and its applications. This invention uses stearate as an internal release agent, solving the problem of high demolding resistance during subsequent pressing caused by using silica sol to replace organic binders in the production of disc ceramics. Stearate also serves as a dopant source; during subsequent heat treatment, the resulting metal carbonate first fills the gaps between barium titanate particles, reducing the internal porosity of the blank and improving the density and density stability of the resulting disc-type barium titanate ceramic capacitor dielectric material. Further heat treatment yields trace amounts of highly active metal oxides that can further fill the gaps between barium titanate particles. The glassy liquid phase formed by silica encapsulates the surface of the barium titanate particles, forming a shell on their surface, thereby increasing the dielectric constant, improving performance stability, and significantly improving the yield.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a method for preparing a dielectric material for a disc-type barium titanate ceramic capacitor, the method comprising the following steps:

[0011] Barium titanate-based mixed powder and stearate are mixed evenly, pressed to obtain a blank, and the blank is sintered to obtain a disc-type barium titanate ceramic capacitor dielectric material.

[0012] The raw materials for the barium titanate-based mixed powder include barium titanate, rare earth oxides, and silica sol.

[0013] This invention uses stearate as a raw material to prepare disc-shaped barium titanate ceramic capacitor dielectric material by adding it to barium titanate-based mixed powder. It has the following advantages: 1) As an internal release agent, it solves the problem of high demolding resistance in the subsequent pressing process caused by using silica sol to replace organic binders in the production of disc ceramics. Compared with the impact of external release agents on the density stability of ceramics, the addition of internal release agent stearate will further improve the density stability; 2) As a doping source, the trace amounts of highly active metal oxides produced by the heat treatment process of stearate can be further doped into the obtained disc-shaped barium titanate ceramic capacitor dielectric material, filling the gaps inside the blank and promoting the glassification of interstitial silica, which forms a shell on the surface of barium titanate particles, thereby improving the density and dielectric constant of the obtained disc-shaped barium titanate ceramic capacitor dielectric material and significantly improving the yield.

[0014] As a preferred technical solution of the present invention, the stearate includes any one or a combination of at least two of calcium stearate, zinc stearate, magnesium stearate or barium stearate, preferably calcium stearate.

[0015] Preferably, the amount of stearate added is 0.2wt% to 1wt% of the mass of the barium titanate-based mixed powder, for example, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, or 1wt%.

[0016] As a preferred technical solution of the present invention, the sintering includes sequentially performing a first-stage sintering, a second-stage sintering, and a third-stage sintering.

[0017] Preferably, the sintering is carried out in an oxygen-containing atmosphere.

[0018] Preferably, the oxygen-containing atmosphere includes an air atmosphere or an oxygen atmosphere.

[0019] As a preferred technical solution of the present invention, the holding temperature of the first sintering stage is 300℃~450℃, such as 300℃, 320℃, 350℃, 380℃, 400℃, 420℃ or 450℃.

[0020] Preferably, the holding time for the first sintering stage is 0.5h to 3h, for example, 0.5h, 1h, 1.5h, 2h, 2.5h or 3h.

[0021] Preferably, the heating rate of the sintering section is 1℃ / min to 5℃ / min, for example, 1℃ / min, 2℃ / min, 3℃ / min, 4℃ / min or 5℃ / min.

[0022] Preferably, the holding temperature for the two-stage sintering is 500℃~600℃, such as 500℃, 520℃, 550℃, 580℃ or 600℃.

[0023] Preferably, the holding time for the two-stage sintering is 1h to 5h, for example, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h or 5h.

[0024] Preferably, the heating rate of the two-stage sintering is 1℃ / min to 3℃ / min, for example, 1℃ / min, 1.5℃ / min, 2℃ / min, 2.5℃ / min or 3℃ / min.

[0025] Preferably, the holding temperature for the three-stage sintering is 1200℃~1300℃, such as 1200℃, 1210℃, 1220℃, 1230℃, 1240℃, 1250℃, 1260℃, 1270℃, 1280℃, 1290℃ or 1300℃.

[0026] Preferably, the holding time for the three-stage sintering is 0.5h to 4h, for example, 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h or 4h.

[0027] Preferably, the heating rate of the three-stage sintering is 4.5℃ / min to 5.5℃ / min, such as 4.5℃ / min, 4.8℃ / min, 5℃ / min, 5.2℃ / min or 5.5℃ / min.

[0028] The first sintering process of this invention is a pyrolysis process of stearate. By controlling the holding temperature of the first sintering to 300℃~450℃, the stearate decomposes, removes the organic matter, and decomposes into metal carbonates that fill the gaps between barium titanate particles in the green body, reducing the internal porosity of the green body and increasing the density and density stability of the resulting disc-shaped barium titanate ceramic capacitor dielectric material, thereby improving performance stability and reducing the defect rate. As the temperature increases (in the second and third sintering processes), trace amounts of highly active metal oxides and silica are decomposed to form a glassy liquid phase. The trace amounts of highly active metal oxides fill the gaps between particles, and the glassy liquid phase coats the surface of the barium titanate particles and forms a shell on the surface of the barium titanate particles, thereby increasing the dielectric constant. The resulting disc-shaped barium titanate ceramic capacitor dielectric material has a high dielectric constant. In addition, the purpose of the second sintering is to remove the carbon remaining after the decomposition of the first sintering, and the third sintering is a densification process for the disc-shaped barium titanate ceramic capacitor dielectric material.

[0029] As a preferred technical solution of the present invention, the pressing pressure is 90MPa~800MPa, such as 90MPa, 150MPa, 200MPa, 250MPa, 300MPa, 350MPa, 400MPa, 450MPa, 500MPa, 550MPa, 600MPa, 650MPa, 700MPa, 750MPa or 800MPa, etc., preferably 100MPa~300MPa.

[0030] As a preferred technical solution of the present invention, the preparation method of the barium titanate-based mixed powder includes the following steps:

[0031] Barium titanate, rare earth oxides and silica sol are mixed and granulated to obtain barium titanate-based mixed powder.

[0032] As a preferred embodiment of the present invention, the silica sol solution includes an acidic silica sol solution or a neutral silica sol solution.

[0033] Preferably, the silica sol solution comprises silica and an aqueous solution.

[0034] Preferably, in the silica sol solution, the silica accounts for 5wt% to 40wt% of the total mass of the silica sol solution, for example, 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, or 40wt%.

[0035] Preferably, the amount of silica sol added is based on the mass of the silica, and the mass of silica in the added silica sol is 0.01wt% to 2.0wt% of the mass of the barium titanate, for example, 0.01wt%, 0.1wt%, 0.3wt%, 0.5wt%, 0.8wt%, 1.0wt%, 1.2wt%, 1.5wt%, 1.8wt%, or 2.0wt%.

[0036] Preferably, the amount of rare earth oxide added is 0.1wt% to 1.5wt% of the mass of barium titanate, for example, 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, 1wt%, 1.1wt%, 1.2wt%, 1.3wt%, 1.4wt%, or 1.5wt%.

[0037] It should be noted that the present invention does not impose specific requirements or special limitations on the types of rare earth oxides. Any type commonly used by those skilled in the art is applicable to the present invention, such as oxides of cerium, yttrium, praseodymium, niobium, gadolinium, holmium, dysprosium, or iridium.

[0038] As a preferred technical solution of the present invention, the preparation method includes the following steps:

[0039] Barium titanate-based mixed powder and stearate are mixed evenly, with the amount of stearate added being 0.2wt%~1wt% of the mass of the barium titanate-based mixed powder. The mixture is pressed at 100MPa~300MPa to obtain a green body. The green body is heated to 300℃~450℃ at a heating rate of 1℃ / min~5℃ / min and held for 0.5h~3h for a first-stage sintering. Then, it is heated to 500℃~600℃ at a heating rate of 1℃ / min~3℃ / min and held for 1h~5h for a second-stage sintering. Finally, it is heated to 1200℃~1300℃ at a heating rate of 4.5℃ / min~5.5℃ / min and held for 0.5h~4h for a third-stage sintering to obtain a disc-type barium titanate ceramic capacitor dielectric material.

[0040] The raw materials for the barium titanate-based mixed powder include barium titanate, rare earth oxides, and silica sol. In the silica sol, the silica accounts for 5 wt% to 40 wt% of the total mass of the silica sol. The amount of silica sol added is based on the mass of silica, with the added silica mass being 0.01 wt% to 2.0 wt% of the mass of barium titanate, and the amount of rare earth oxides added being 0.1 wt% to 1.5 wt% of the mass of barium titanate.

[0041] In a second aspect, the present invention also provides a disc-type barium titanate ceramic capacitor dielectric material, which is prepared according to the preparation method described in the first aspect.

[0042] As a preferred technical solution of the present invention, the dielectric constant of the dielectric material of the disc-type barium titanate ceramic capacitor is 3000~3500, such as 3000, 3050, 3100, 3150, 3200, 3250, 3300, 3350, 3400, 3450 or 3500, etc., preferably 3050~3500.

[0043] Preferably, the dielectric material of the disc-type barium titanate ceramic capacitor has a density of 5.85 g / cm³. 3 ~5.95g / cm 3 For example, 5.85 g / cm³ 3 5.86 g / cm 3 5.87 g / cm 3 5.88g / cm 3 5.89 g / cm 3 5.90g / cm 3 5.91 g / cm 3 5.92g / cm 3 5.93g / cm3 5.94g / cm 3 Or 5.95g / cm 3 The preferred value is 5.90 g / cm³. 3 ~5.95g / cm 3 .

[0044] Secondly, the present invention also provides an application of the disc-type barium titanate ceramic capacitor dielectric material, which is applied to electronic components.

[0045] Compared with the prior art, the present invention has at least the following beneficial effects:

[0046] 1) This invention uses stearate as an internal release agent, which solves the problem of high demolding resistance in the subsequent pressing process caused by using silica sol liquid to replace organic binder in the production of ceramic sheets. Compared with the situation where spraying external release agent affects the density stability of ceramics, the addition of internal release agent stearate will further make the density stability higher.

[0047] 2) In this invention, stearate is also used as a dopant source. During the subsequent heat treatment, the obtained metal carbonate first fills the gaps between barium titanate particles, reducing the porosity inside the blank and improving the density and density stability of the obtained disc-shaped barium titanate ceramic capacitor dielectric material. The trace amounts of highly active metal oxides obtained by further heat treatment can further fill the gaps between barium titanate particles. The glassy liquid phase formed by silica encapsulates the surface of barium titanate particles and forms a shell on its surface, thereby increasing the dielectric constant, improving performance stability, and significantly improving the yield. Detailed Implementation

[0048] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0049] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0050] The silica sol solution used in the specific embodiments of this invention is a commercially available aqueous colloid with a silica content of 5 wt%, wherein the sodium ion content of impurities is <0.5 wt%, and the silica particles are nanoscale with a particle size of <20 nm.

[0051] The barium titanate-based mixed powder used in the specific embodiments of this invention is prepared by the following method, which includes the following steps:

[0052] Weigh a certain mass of barium titanate, add 1.5 wt% of barium titanate mixed powder of Nb2O5 and CeO2 (mass ratio 1:1), and silica sol solution. In the added silica sol solution, the mass of silicon dioxide is 0.2 wt% of the mass of barium titanate. After mixing and granulating the above three, barium titanate-based mixed powder is obtained.

[0053] Example 1

[0054] This embodiment provides a method for preparing a dielectric material for a disc-type barium titanate ceramic capacitor, the method comprising the following steps:

[0055] Barium titanate-based mixed powder and calcium stearate were mixed evenly, with the amount of calcium stearate added being 0.5 wt% of the mass of barium titanate-based mixed powder. The mixture was pressed at 100 MPa to obtain a disc with a diameter of 10 mm and a thickness of 2 mm. Then, the temperature was increased to 300 °C at 2 °C / min and held for 1 h for a first-stage sintering. Next, the temperature was increased to 550 °C at 2 °C / min and held for 3 h for a second-stage sintering. Finally, the temperature was increased to 1250 °C at 5 °C / min and held for 2 h for a third-stage sintering. The mixture was then naturally cooled to room temperature to obtain a disc-type barium titanate ceramic capacitor dielectric material.

[0056] Example 2

[0057] This embodiment provides a method for preparing a disc-type barium titanate ceramic capacitor dielectric material. The difference between this method and that of Embodiment 1 is that the amount of calcium stearate added is 0.2 wt% of the mass of the barium titanate-based mixed powder, while the rest of the preparation method and parameters remain the same as in Embodiment 1.

[0058] Example 3

[0059] This embodiment provides a method for preparing a disc-type barium titanate ceramic capacitor dielectric material. The difference between this method and that of Embodiment 1 is that the amount of calcium stearate added is 0.3 wt% of the mass of the barium titanate-based mixed powder, while the rest of the preparation method and parameters remain the same as those of Embodiment 1.

[0060] Example 4

[0061] This embodiment provides a method for preparing a disc-type barium titanate ceramic capacitor dielectric material. The difference between this method and that of Embodiment 1 is that the amount of calcium stearate added is 0.4 wt% of the mass of the barium titanate-based mixed powder, while the rest of the preparation method and parameters remain the same as those of Embodiment 1.

[0062] Example 5

[0063] This embodiment provides a method for preparing a disc-type barium titanate ceramic capacitor dielectric material. The difference between this method and that of Embodiment 1 is that the amount of calcium stearate added is 0.7 wt% of the mass of the barium titanate-based mixed powder, while the rest of the preparation method and parameters remain the same as those of Embodiment 1.

[0064] Example 6

[0065] This embodiment provides a method for preparing a dielectric material for a disc-type barium titanate ceramic capacitor, the method comprising the following steps:

[0066] Barium titanate-based mixed powder and magnesium stearate were mixed evenly, with the amount of magnesium stearate added being 0.6 wt% of the mass of barium titanate-based mixed powder. The mixture was pressed at 200 MPa to obtain discs with a diameter of 10 mm and a thickness of 2 mm. Then, the temperature was increased to 450 °C at 2 °C / min and held for 0.5 h for the first stage of sintering. The temperature was then increased to 500 °C at 1 °C / min and held for 5 h for the second stage of sintering. Finally, the temperature was increased to 1200 °C at 5.5 °C / min and held for 4 h for the third stage of sintering. The mixture was then naturally cooled to room temperature to obtain disc-shaped barium titanate ceramic capacitor dielectric material.

[0067] Example 7

[0068] This embodiment provides a method for preparing a dielectric material for a disc-type barium titanate ceramic capacitor, the method comprising the following steps:

[0069] Barium titanate-based mixed powder and zinc stearate were mixed evenly, with the amount of zinc stearate added being 1 wt% of the mass of barium titanate-based mixed powder. The mixture was pressed at 300 MPa to obtain discs with a diameter of 10 mm and a thickness of 2 mm. Then, the temperature was increased to 350 °C at 2 °C / min and held for 3 h for a first-stage sintering. Next, the temperature was increased to 600 °C at 3 °C / min and held for 1 h for a second-stage sintering. Finally, the temperature was increased to 1300 °C at 4.5 °C / min and held for 0.5 h for a third-stage sintering. The mixture was then naturally cooled to room temperature to obtain disc-type barium titanate ceramic capacitor dielectric material.

[0070] Example 8

[0071] This embodiment provides a method for preparing a dielectric material for a disc-type barium titanate ceramic capacitor. The difference between this method and that of Embodiment 1 is that calcium stearate is replaced with barium stearate, while the rest of the preparation method and parameters remain the same as those of Embodiment 1.

[0072] Example 9

[0073] This embodiment provides a method for preparing a disc-type barium titanate ceramic capacitor dielectric material. The difference between this method and that of Embodiment 1 is that the amount of calcium stearate added is 1.1 wt% of the mass of the barium titanate-based mixed powder, while the rest of the preparation method and parameters remain the same as those of Embodiment 1.

[0074] Example 10

[0075] This embodiment provides a method for preparing a dielectric material for a disc-type barium titanate ceramic capacitor. The difference between this method and that of Embodiment 1 is that the sintering temperature of the first stage is 250°C, while the rest of the preparation method and parameters remain the same as those of Embodiment 1.

[0076] Example 11

[0077] This embodiment provides a method for preparing a dielectric material for a disc-type barium titanate ceramic capacitor. The difference between this method and that of Embodiment 1 is that the sintering temperature of the first stage is 500°C, while the rest of the preparation method and parameters remain the same as those of Embodiment 1.

[0078] Example 12

[0079] This embodiment provides a method for preparing a dielectric material for a disc-type barium titanate ceramic capacitor. The difference between this method and that of Embodiment 1 is that the two-stage sintering is omitted. After the first-stage sintering is completed, the temperature is directly increased to 1250℃ at 5℃ / min and held for 2 hours for a third-stage sintering, followed by natural cooling to room temperature. The remaining preparation methods and parameters are consistent with those of Embodiment 1.

[0080] Comparative Example 1

[0081] This comparative example provides a method for preparing a disc-type barium titanate ceramic capacitor dielectric material. The difference between this preparation method and Example 1 is that the addition of calcium stearate is omitted, and the barium titanate-based mixed powder is directly pressed. The remaining preparation methods and parameters are consistent with those of Example 1.

[0082] Comparative Example 2

[0083] This comparative example provides a method for preparing a dielectric material for a disc-type barium titanate ceramic capacitor. The difference between this method and Example 1 is that calcium stearate is replaced with an equal amount of stearic acid, while the rest of the preparation method and parameters remain the same as in Example 1.

[0084] Comparative Example 3

[0085] This comparative example provides a method for preparing a disc-type barium titanate ceramic capacitor dielectric material. The difference between this preparation method and Example 1 is that calcium stearate is used as an external release agent. Calcium stearate is coated onto the inner surface of the mold, and then the barium titanate-based mixed powder is directly pressed to obtain a disc. The remaining preparation methods and parameters are consistent with Example 1.

[0086] The dielectric materials of the disc-type barium titanate ceramic capacitors provided in Examples 1-12 and Comparative Examples 1-3 were tested for density and dielectric constant, and the dielectric constant improvement rate (relative to Comparative Example 1) and yield were calculated. The specific results are shown in Table 1.

[0087] Table 1

[0088]

[0089] The test results show that:

[0090] (1) As can be seen from Examples 1 to 8 and Comparative Example 1, the present invention solves the problem of high demolding resistance in the subsequent pressing process caused by using silica sol liquid to replace organic binder in the production of disc ceramics by using stearate as an internal release agent. It also acts as a dopant source. In the subsequent heat treatment process, the obtained metal carbonate first fills the gaps between barium titanate particles, reduces the porosity inside the blank, and improves the density and density stability of the obtained disc barium titanate ceramic capacitor dielectric material. The trace amount of highly active metal oxide obtained by further heat treatment can further fill the gaps between barium titanate particles. The glassy liquid phase formed by silica encapsulates the surface of barium titanate particles and forms a shell on its surface, thereby improving the dielectric constant, improving performance stability, and significantly improving the yield. Specifically, the dielectric constant of the disc barium titanate ceramic capacitor dielectric material is improved by 2.2% to 5%, and the density is >5.90 g / cm³. 3 The highest concentration can reach 5.937 g / cm³. 3 The yield rate is >97.0%, and can reach up to 99.3%.

[0091] However, when calcium stearate was omitted in Comparative Example 1, the density of the dielectric material in the disc-type barium titanate ceramic capacitor could only reach 5.885 g / cm³. 3 The yield rate was greatly reduced.

[0092] (2) As can be seen from Examples 1 and 9, by further controlling the amount of stearate added to 0.2wt%~1wt% of the mass of the barium titanate-based mixed powder, the present invention can effectively solve the problem of large demolding resistance in the subsequent pressing process caused by using silica sol liquid to replace organic binder in the production of disc ceramics, improve the dielectric constant, improve performance stability, and significantly improve the yield. If the amount of stearate added is too much, it will have the opposite effect, resulting in a decrease in dielectric constant.

[0093] (3) As can be seen from Examples 1 and 10-11, the present invention further controls the holding temperature of the first sintering stage to 300℃~450℃ and holds it for a certain time, so that the stearate decomposes, removes the organic matter, and decomposes into metal carbonates that fill the gaps between the barium titanate particles in the green body, reducing the internal porosity of the green body, increasing the density and density stability of the obtained disc-type barium titanate ceramic capacitor dielectric material, thereby improving the performance stability and reducing the defect rate. If the holding temperature of the first sintering stage is too low or too high, it will lead to a decrease in product density and a decrease in the dielectric constant of the product.

[0094] (4) As can be seen from Examples 1 and 12, if the process of removing residual carbon after the first sintering is omitted in the second sintering process, and the third sintering is carried out by heating to 1250℃ at 5℃ / min and holding for 2 hours after the first sintering is completed, and then naturally cooled to room temperature, the residual carbon will not be completely decomposed and removed. Some residual carbon will remain inside the material, which will affect the product performance of the dielectric material of the disc barium titanate ceramic capacitor.

[0095] (5) As can be seen from Example 1 and Comparative Examples 2-3, when stearic acid is used as an internal release agent (Comparative Example 2) and calcium stearate is used as an external release agent (Comparative Example 3), neither can effectively improve the product performance of the dielectric material of the disc barium titanate ceramic capacitor.

[0096] In summary, this invention uses stearate as an internal release agent, which solves the problem of high demolding resistance during subsequent pressing caused by using silica sol liquid to replace organic binders in the production of disc ceramics. It also serves as a dopant source. During subsequent heat treatment, the obtained metal carbonate first fills the gaps between barium titanate particles, reducing the internal porosity of the green body and improving the density and density stability of the resulting disc barium titanate ceramic capacitor dielectric material. The trace amounts of highly active metal oxides obtained by further heat treatment can further fill the gaps between barium titanate particles. The glassy liquid phase formed by silica encapsulates the surface of barium titanate particles, forming a shell on its surface, thereby increasing the dielectric constant, improving performance stability, and significantly improving the yield.

[0097] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a dielectric material for a disc-type barium titanate ceramic capacitor, characterized in that, The preparation method includes the following steps: Barium titanate-based mixed powder and stearate are mixed evenly, pressed to obtain a blank, and the blank is sintered to obtain a disc-type barium titanate ceramic capacitor dielectric material. The raw materials for the barium titanate-based mixed powder include barium titanate, rare earth oxides, and silica sol.

2. The preparation method according to claim 1, characterized in that, The stearate includes any one or a combination of at least two of calcium stearate, zinc stearate, magnesium stearate or barium stearate, preferably calcium stearate; Preferably, the amount of stearate added is 0.2wt% to 1wt% of the mass of the barium titanate-based mixed powder.

3. The preparation method according to claim 1 or 2, characterized in that, The sintering includes sequentially performed first-stage sintering, second-stage sintering, and third-stage sintering; Preferably, the sintering is carried out in an oxygen-containing atmosphere; Preferably, the oxygen-containing atmosphere includes an air atmosphere or an oxygen atmosphere.

4. The preparation method according to claim 3, characterized in that, The holding temperature for the first sintering stage is 300℃~450℃; Preferably, the holding time for the first sintering stage is 0.5h to 3h; Preferably, the holding temperature for the two-stage sintering is 500℃~600℃; Preferably, the holding time for the two-stage sintering is 1 hour to 5 hours; Preferably, the heating rate of the two-stage sintering is 1℃ / min to 3℃ / min; Preferably, the holding temperature for the three-stage sintering is 1200℃~1300℃; Preferably, the holding time for the three-stage sintering is 0.5h to 4h; Preferably, the heating rate of the three-stage sintering is 4.5℃ / min to 5.5℃ / min.

5. The preparation method according to any one of claims 1 to 4, characterized in that, The pressing pressure is 90MPa~800MPa, preferably 100MPa~300MPa.

6. The preparation method according to any one of claims 1 to 5, characterized in that, The preparation method of the barium titanate-based mixed powder includes the following steps: Barium titanate, rare earth oxides and silica sol are mixed and granulated to obtain barium titanate-based mixed powder.

7. The preparation method according to any one of claims 6, characterized in that, The silica sol solution includes an acidic silica sol solution or a neutral silica sol solution; Preferably, the silica sol solution comprises silica and an aqueous solution; Preferably, in the silica sol solution, the silica accounts for 5 wt% to 40 wt% of the total mass of the silica sol solution; Preferably, the amount of silica sol added is based on the mass of the silica, and the mass of silica in the added silica sol is 0.01wt%~2.0wt% of the mass of the barium titanate. Preferably, the amount of rare earth oxide added is 0.1wt% to 1.5wt% of the mass of barium titanate.

8. A dielectric material for a disc-type barium titanate ceramic capacitor, characterized in that, The dielectric material of the disc-type barium titanate ceramic capacitor is prepared according to any one of claims 1 to 7.

9. The dielectric material of the disc-type barium titanate ceramic capacitor according to claim 8, characterized in that, The dielectric constant of the dielectric material of the disc-type barium titanate ceramic capacitor is 3000~3500, preferably 3050~3500; Preferably, the dielectric material of the disc-type barium titanate ceramic capacitor has a density of 5.85 g / cm³. 3 ~5.95g / cm 3 The preferred value is 5.90 g / cm³. 3 ~5.95g / cm 3 .

10. An application of a dielectric material for a disc-type barium titanate ceramic capacitor, characterized in that, The disc-type barium titanate ceramic capacitor dielectric material as described in claim 8 or 9 is applied to electronic components.

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