High-voltage capacitor, preparation method thereof and primary and secondary fusion pole based on high-voltage capacitor

Abstract

The preparation method of the high-voltage capacitor comprises the following steps: adding yttrium oxide and lithium phosphate into calcium strontium zirconate titanate powder, and uniformly mixing to prepare a capacitor ceramic matrix; the preparation method comprises the following steps: uniformly dry-mixing titanium oxide, barium carbonate and strontium carbonate, adding a first binder, pressing into a wafer, and sintering to obtain a barium strontium metatitanate high-temperature ferroelectric; adding ethanol as a solvent into the mixed powder of the capacitor ceramic matrix and the barium strontium metatitanate high-temperature ferroelectric, then adding a second binder, a dispersant and a plasticizer to prepare a tape casting slurry, carrying out tape casting to obtain a tape casting sheet, and pressing the tape casting sheet into a thin sheet after lamination; and carrying out silk-screen printing of nickel paste on the sheet, laminating, pressing into a block, and sintering in 95% nitrogen and 5% hydrogen atmosphere to obtain the layered high-voltage capacitor. The multi-layer capacitor prepared by the invention meets the space use requirement of the pole, and the cold and hot cycle use performance of the capacitor is improved.

Description

Technical Field

[0001] The present invention belongs to the field of electric power voltage signal acquisition, and relates to a high-voltage capacitor, a preparation method thereof, and a primary-secondary fusion pole based thereon. Background Art

[0002] In today's booming power industry, power equipment, as a core component of the power system, has a significant impact on the safe and stable operation of the entire power grid through its performance and reliability. With the continuous advancement of power technology, the integration of primary and secondary equipment within power equipment is becoming increasingly evident. Primary equipment is beginning to integrate the voltage signal acquisition capabilities of some secondary equipment, significantly improving the intelligence and operational efficiency of power equipment.

[0003] The voltage transformer is a component in a fused primary / secondary pole. Currently, fused primary / secondary poles are manufactured using an integrated casting process that combines the high-voltage capacitors of the secondary equipment. This not only improves the overall performance and reliability of the pole, but also effectively reduces the equipment size and production costs, which is of great significance for promoting the miniaturization and integration of power equipment. However, in actual application, fused primary / secondary poles face many challenges. Due to distribution network requirements, the conductive rod on the outgoing side of the pole only has space reserved for the assembly of a φ37×26mm high-voltage capacitor. This space limitation places extremely high demands on the design and manufacture of the capacitors, requiring high performance and stability within such a confined space.

[0004] To meet this space requirement while maintaining capacitor performance, capacitors are currently made of strontium titanate ceramic with a dielectric constant of 700. Strontium titanate ceramics offer advantages such as high dielectric constant and low loss, enabling high capacitance within a compact size, thus meeting the required capacitance of the terminal. However, the pursuit of a high dielectric constant requires a temperature gradient of 100 ppm / °C (-40°C to 125°C), which requires the inclusion of a significant amount of lead in the ceramic formulation. While this addition improves the dielectric properties and temperature stability of the ceramic to some extent, it imposes extremely demanding production conditions. Even with complex production processes and stringent conditions, performance remains suboptimal. In actual use, terminals are subject to frequent thermal cycling. Differences in thermal expansion coefficients between different materials can lead to stress variations between internal components during operation. Over time, the low-voltage capacitor undergoes subtle internal structural changes, affecting its electrical performance. Over time, the temperature drift characteristic curve of the capacitor shifts, resulting in a decrease in the accuracy of voltage signal acquisition. To restore the performance of the capacitor, it is necessary to adjust it to match the temperature drift characteristic curve of the capacitor. This not only increases the maintenance cost and workload of the equipment, but may also affect the normal operation of the power system. Summary of the Invention

[0005] The purpose of the present invention is to provide a high-voltage capacitor and a preparation method thereof, and a primary and secondary fused pole based thereon, so as to solve the problem that the electrical performance of the existing capacitor is affected by the impact of hot and cold cycles.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: A method for preparing a high-voltage capacitor, comprising: Yttrium trioxide and lithium phosphate are added to calcium strontium zirconate titanate powder and mixed evenly to prepare a capacitor ceramic matrix; Titanium oxide, barium carbonate and strontium carbonate are dry-mixed uniformly, a first binder is added, the mixture is pressed into a disc, and sintered to obtain a barium strontium metatitanate high-temperature ferroelectric; Adding ethanol as a solvent to a mixed powder of a capacitor ceramic matrix and barium strontium metatitanate high-temperature ferroelectric, then adding a second binder, a dispersant and a plasticizer to prepare a casting slurry, casting a casting sheet, and laminating and pressing it into a sheet; Nickel paste is screen-printed on the thin sheets, which are then stacked and pressed into blocks. They are then sintered in an atmosphere of 95% nitrogen and 5% hydrogen to obtain layered high-voltage capacitors.

[0007] Furthermore, the calcium strontium zirconate titanate powder is Ca y Sr 1-y (Ti x Zr 1-x )O3, where 0 <y<0.5,0<x<0.3; The barium strontium metatitanate is Ba 1-m Sr m Ti2O5, of which 0 <m<0.1。

[0008] Furthermore, the mass of the yttrium oxide is 0.1% to 1% of the mass of the calcium strontium zirconate titanate powder, and the mass of the lithium phosphate is 0.5% to 1.5% of the mass of the calcium strontium zirconate titanate powder.

[0009] Furthermore, the mass of the titanium oxide is 40% to 55% of the mass of the mixture of titanium oxide, barium carbonate and strontium carbonate, the mass of the barium carbonate is 45% to 60% of the mass of the mixture of titanium oxide, barium carbonate and strontium carbonate, and the mass of the strontium carbonate is 0.01% to 1% of the mass of the mixture of titanium oxide, barium carbonate and strontium carbonate.

[0010] Furthermore, the first binder is 17-88 PVA, and the mass of the first binder is 1% to 1.5% of the mass of the mixture of titanium oxide, barium carbonate and strontium carbonate.

[0011] Furthermore, the pressing pressure of the disc is 120 MPa, the sintering temperature of the disc is 1285° C., and the holding time is 10 h.

[0012] Furthermore, the mass of the capacitor ceramic matrix and the barium strontium metatitanate high-temperature ferroelectric mixed powder is 40% to 60% of the mass of the casting slurry, the mass of the ethanol is 30% to 35% of the mass of the casting slurry, the second binder is PVB, the mass of the second binder is 3% to 5% of the mass of the casting slurry, the dispersant is sorbitan trioleate, the mass of the dispersant is 0.1% to 0.6% of the mass of the casting slurry dry powder, and the plasticizer is dibutyl phthalate, the mass of the plasticizer is 5% to 20% of the mass of the second binder; The mass of the barium strontium metatitanate high-temperature ferroelectric is 1% to 12% of the mass of the mixed powder of the capacitor ceramic matrix and the barium strontium metatitanate high-temperature ferroelectric.

[0013] Furthermore, the pressing pressure of the sheet is 20 MPa, and the thickness of the screen-printed nickel paste on the sheet is 5 to 10 mm; The pressing pressure of the block is 120 MPa, and the sintering temperature of the block is 1150-1300°C.

[0014] A high-voltage capacitor is manufactured by the manufacturing method.

[0015] A primary-secondary fusion pole is made of the high-voltage capacitor.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a method for preparing a high-voltage capacitor. Yttrium oxide and lithium phosphate are added to calcium strontium zirconate titanate powder to prepare a capacitor ceramic matrix. Ion doping is used to modify the ceramic's crystal structure and optimize grain boundary properties, thereby increasing the dielectric constant of the ceramic. Titanium oxide, barium carbonate, and strontium carbonate are dry-mixed uniformly, a first binder is added, the mixture is pressed into a disc, and sintered to obtain a barium strontium metatitanate high-temperature ferroelectric. This method enhances the dielectric response of the capacitor, further improving the dielectric properties of the capacitor and contributing to improved performance under high-voltage conditions. Ethanol is added as a solvent to the mixed powder of the capacitor ceramic matrix and the barium strontium metatitanate high-temperature ferroelectric. A second binder, a dispersant, and a plasticizer are then added to form a casting slurry. Cast sheets are then formed, laminated, and pressed into thin sheets. This method allows for precise control of the capacitor's size and thickness, ensuring consistency and stability, and facilitates large-scale production of high-quality high-voltage capacitors. Nickel paste is screen-printed on the thin sheet. The screen-printing process accurately forms an electrode pattern on the capacitor surface, ensuring good contact between the electrodes and the capacitor matrix and improving the capacitor's conductivity. After lamination, it is pressed into a block and sintered in an atmosphere of 95% nitrogen and 5% hydrogen to obtain a layered high-voltage capacitor. Sintering in a mixed atmosphere of nitrogen and hydrogen, hydrogen has a certain reducing property, which can prevent the electrode material from being oxidized during the sintering process, ensuring the conductivity and stability of the electrode. At the same time, this specific sintering atmosphere helps to optimize the microstructure of the capacitor and improve the mechanical strength and electrical properties of the capacitor. The present invention obtains a paraelectric ceramic matrix by doping strontium calcium zirconate with yttrium and phosphorus, and at the same time introduces strontium barium metatitanate high-temperature ferroelectric compensation temperature coefficient, so that its dielectric constant reaches more than 100, the required volume content reaches 250PF, the temperature coefficient is less than 30ppm / ℃, and the performance of NP0 porcelain parts is achieved. Then, a multilayer capacitor is prepared by tape casting and lamination, which meets the space requirements of the pole and improves the hot and cold cycle performance of the capacitor. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 This is a schematic diagram of the high-voltage capacitor structure prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0019] To facilitate understanding of the features and effects of the present invention by those skilled in the art, the following provides a general description and definition of the terms and expressions used in the specification and claims. Unless otherwise indicated, all technical and scientific terms used herein have the ordinary meanings as understood by those skilled in the art regarding the present invention. In the event of conflict, the definitions in this specification shall prevail.

[0020] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0021] All features, such as values, amounts, contents, and concentrations, described herein as numerical ranges or percentage ranges are provided for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to include and specifically disclose all possible subranges and individual values ​​within the range (including integers and fractions).

[0022] In this document, unless otherwise specified, “include,” “including,” “contains,” “has” or similar terms cover the meanings of “consisting of” and “mainly consisting of,” for example, “A includes a” covers the meanings of “A includes a and other” and “A only includes a.”

[0023] In this document, for the sake of brevity, not all possible combinations of the various technical features in each embodiment or example are described. Therefore, as long as there are no contradictions in the combination of these technical features, the various technical features in each embodiment or example can be combined in any way, and all possible combinations should be considered to be within the scope of this specification.

[0024] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. The present invention will be further elaborated in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. The embodiments described are part of the embodiments of the present invention, not all of the embodiments. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. In addition, it should be understood that after reading the contents taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention.

[0025] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiments of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples, unless they are contradictory.

[0026] In order to make those skilled in the art more clearly understand the technical solutions of the present invention, the following examples are given for illustration. It should be pointed out that the following examples do not limit the scope of protection claimed by the present invention. Unless otherwise specified, the raw materials, reagents or devices used in the following examples can be obtained from conventional commercial channels, or can be obtained by existing known methods. Conventional instruments and equipment in the field are used in the following examples. The experimental methods for which specific conditions are not specified in the following examples are generally carried out under conventional conditions or under conditions recommended by the manufacturer. Various raw materials used in the following examples are conventional commercial products, unless otherwise specified, and their specifications are conventional specifications in the field. In the specification of the present invention and the following examples, unless otherwise specified, "%" represents weight percentage, "part" represents weight part, and ratio represents weight ratio.

[0027] The present invention is described in further detail below with reference to the accompanying drawings: The present invention provides a method for preparing a high-voltage capacitor, which specifically comprises the following steps: Step 1. Prepare capacitor ceramic matrix by yttrium phosphorus modified calcium strontium zirconate titanate powder Calcium strontium zirconate titanate powder is Ca y Sr 1-y (Ti x Zr 1-x )O3, where 0 <y<0.5,0<x<0.3。

[0028] Yttrium trioxide (0.1% to 1% by mass of the calcium strontium zirconate titanate powder) and lithium phosphate (0.5% to 1.5% by mass of the calcium strontium zirconate titanate powder) are added to calcium strontium zirconate titanate powder and mixed evenly to prepare a capacitor ceramic matrix.

[0029] Step 2. Barium strontium metatitanate (Ba 1-m Sr m Ti2O5) high temperature ferroelectric preparation, where 0 <m<0.1。

[0030] In a ball mill, 40% to 55% titanium oxide, 45% to 60% barium carbonate, and 0.01% to 1% strontium carbonate (by mass percentage) are added and dry-mixed for 3 hours. 17-88PVA (1% to 1.5% by mass of the titanium oxide, barium carbonate, and strontium carbonate mixture) is then added as a first binder. The mixture is pressed into 5-10 mm diameter discs at a pressure of 120 MPa. The discs are then sintered in an air-fired furnace at 1285°C and held at that temperature for 10 hours to obtain a high-temperature ferroelectric preform of barium strontium metatitanate.

[0031] The preform of the high-temperature ferroelectric barium metatitanate is tested and the dielectric constant at 125°C should be greater than 100. The qualified preform is ball-milled to a ball-milled ceramic particle size of less than 0.5 μm, and the preparation of the high-temperature ferroelectric barium metatitanate is completed.

[0032] Step 3. Casting substrate preparation Ethanol is added to a mixture of capacitor ceramic matrix and barium strontium metatitanate high-temperature ferroelectric powders. Ethanol is used as the solvent for the tape casting slurry, and PVB is added as a second binder, a dispersant, and a plasticizer to form the tape casting slurry. The mixture of capacitor ceramic matrix and barium strontium metatitanate high-temperature ferroelectric powders accounts for 40% to 60%, ethanol accounts for 30% to 35%, and PVB accounts for 3% to 5%. The dispersant is S85 (sorbitan trioleate), and the mass of the dispersant is 0.1% to 0.6% of the mass of the tape casting slurry dry powder. The plasticizer is DBP (dibutyl phthalate), and the mass of the plasticizer is 5% to 20% of the mass of the second binder PVB.

[0033] The mass of the barium strontium metatitanate high-temperature ferroelectric is 1% to 12% of the mass of the mixed powder of the capacitor ceramic matrix and the barium strontium metatitanate high-temperature ferroelectric.

[0034] The calcium strontium zirconate titanate and barium strontium metatitanate powders used for tape casting have a particle size of less than 0.8 μm, and the viscosity of the tape casting slurry is 6,000 to 7,000 mp·s. A 1 mm thick tape sheet is cast on a tape casting machine, then stacked into 7 to 10 sheets. This is then pressed into a 6 to 9 mm sheet using an isostatic press at 20 MPa. Nickel paste is then screen-printed onto the sheet, with a thickness of 5 to 10 mm.

[0035] Step 4. Fabrication of layered high-voltage capacitors 5-10mm thin sheets, screen-printed with nickel paste, are manually stacked in 3-4 layers and pressed into blocks using an isostatic press at 120 MPa. Sintering at 1150-1300°C in an atmosphere of 95% nitrogen and 5% hydrogen results in a layered high-voltage capacitor.

[0036] The present invention is described in further detail below through specific embodiments: Example 1: A method for preparing a high-voltage capacitor comprises the following steps: Step 1. Prepare capacitor ceramic matrix by yttrium phosphorus modified calcium strontium zirconate titanate powder Calcium strontium zirconate titanate powder is Ca 0.4 Sr 0.6 (Ti 0.2 Zr 0.8 )O3.

[0037] 1 g of yttrium trioxide and 0.6 g of lithium phosphate were added to 100 g of calcium strontium zirconate titanate powder and mixed evenly to prepare a capacitor ceramic matrix.

[0038] Step 2. Barium strontium metatitanate (Ba 0.98 Sr 0.02 Preparation of high temperature ferroelectrics 100g of titanium oxide, 110g of barium carbonate, and 0.05g of strontium carbonate were added to a ball mill and dry-mixed for 3 hours. 1% of the mass of the titanium oxide, barium carbonate, and strontium carbonate mixture was added as a first binder. The mixture was pressed into a φ5 disc at 120 MPa. The disc was placed in an air sintering furnace, sintered at 1285°C, and then held at that temperature for 10 hours to obtain a preform of a high-temperature ferroelectric barium metatitanate. The preform was ball-milled to a particle size of less than 0.5µm, completing the preparation of the high-temperature ferroelectric barium metatitanate.

[0039] Step 3. Casting substrate preparation Ethanol is added to a mixture of capacitor ceramic matrix and barium strontium metatitanate high-temperature ferroelectric powders, using ethanol as the solvent for the tape casting slurry. PVB is then added as a second binder, a dispersant, and a plasticizer to form the tape casting slurry. The mixture of capacitor ceramic matrix and barium strontium metatitanate high-temperature ferroelectric powders accounts for 40g, ethanol accounts for 55g, and PVB accounts for 5g. The dispersant is S85, which is 0.4% of the mass of the tape casting slurry dry powder. The plasticizer is DBP, which is 10% of the mass of the PVB.

[0040] The mass of the barium strontium metatitanate high-temperature ferroelectric is 1% of the mass of the mixed powder of the capacitor ceramic matrix and the barium strontium metatitanate high-temperature ferroelectric.

[0041] The calcium strontium zirconate titanate and barium strontium metatitanate powders used for tape casting have a particle size of less than 0.8 μm, and the slurry viscosity is 6000 mp·s. A 1mm thick sheet is cast on a tape casting machine, then stacked into eight sheets. The sheets are then pressed into 6mm sheets using an isostatic press at 20 MPa. Nickel paste is then screen-printed onto the sheets to a thickness of 5mm.

[0042] Step 4. Fabrication of layered high-voltage capacitors The 5mm thin sheets with nickel paste printed on them were manually stacked in 3 layers and pressed into blocks using an isostatic press at a pressure of 120MPa. The blocks were sintered at 1150℃ in an atmosphere of 95% nitrogen and 5% hydrogen to obtain layered high-voltage capacitors. After sintering, the high-voltage capacitors were ground to a diameter of φ37 and a total height of 27mm. Figure 1 shown.

[0043] Example 2: A method for preparing a high-voltage capacitor comprises the following steps: Step 1. Prepare capacitor ceramic matrix by yttrium phosphorus modified calcium strontium zirconate titanate powder Calcium strontium zirconate titanate powder is Ca 0.4 Sr 0.6 (Ti 0.2 Zr 0.8 )O3.

[0044] 1 g of yttrium trioxide and 0.6 g of lithium phosphate were added to 100 g of calcium strontium zirconate titanate powder and mixed evenly to prepare a capacitor ceramic matrix.

[0045] Step 2. Barium strontium metatitanate (Ba 0.98 Sr 0.02 Preparation of high temperature ferroelectrics 100g of titanium oxide, 110g of barium carbonate, and 0.05g of strontium carbonate were added to a ball mill and dry-mixed for 3 hours. 17-88PVA (1.5% by weight of the titanium oxide, barium carbonate, and strontium carbonate mixture) was then added as a first binder. The mixture was pressed into a φ7 disc at 120 MPa. The disc was placed in an air sintering furnace, sintered at 1180°C, and held at that temperature for 10 hours to obtain a barium strontium metatitanate high-temperature ferroelectric preform. The preform was ball-milled to a ceramic particle size of less than 0.5 μm, completing the preparation of the barium strontium metatitanate high-temperature ferroelectric.

[0046] Step 3. Casting substrate preparation Ethanol was added to a mixture of capacitor ceramic matrix and barium strontium metatitanate high-temperature ferroelectric powders. Ethanol was used as the solvent for the tape casting slurry. PVB was then added as a second binder, a dispersant, and a plasticizer to prepare the tape casting slurry. The mixture contained 50g of the capacitor ceramic matrix and barium strontium metatitanate high-temperature ferroelectric powders, 46g of ethanol, and 4g of PVB. The dispersant was S85, which accounted for 0.6% of the mass of the dry powder of the tape casting slurry. The plasticizer was DBP, which accounted for 15% of the mass of the PVB in the tape casting slurry.

[0047] The mass of the barium strontium metatitanate high-temperature ferroelectric is 3% of the mass of the mixed powder of the capacitor ceramic matrix and the barium strontium metatitanate high-temperature ferroelectric.

[0048] The calcium strontium zirconate titanate and barium strontium metatitanate powders used for tape casting have a particle size of less than 0.8 μm, and the slurry viscosity is 6500 mp·s. A 1mm thick sheet is cast on a tape casting machine, then stacked into seven sheets. The sheets are then pressed into 8mm sheets using an isostatic press at 20 MPa. Nickel paste is then screen-printed onto the sheets to a thickness of 8mm.

[0049] Step 4. Fabrication of layered high-voltage capacitors 8mm thin sheets, screen-printed with nickel paste, were manually stacked in three layers and pressed into blocks using an isostatic press at 120 MPa. Sintering at 1200°C in an atmosphere of 95% nitrogen and 5% hydrogen resulted in a layered high-voltage capacitor.

[0050] Example 3: A method for preparing a high-voltage capacitor comprises the following steps: Step 1. Prepare capacitor ceramic matrix by yttrium phosphorus modified calcium strontium zirconate titanate powder Calcium strontium zirconate titanate powder is Ca 0.4 Sr 0.6 (Ti 0.2 Zr 0.8 )O3.

[0051] 1 g of yttrium trioxide and 0.6 g of lithium phosphate were added to 100 g of calcium strontium zirconate titanate powder and mixed evenly to prepare a capacitor ceramic matrix.

[0052] Step 2. Barium strontium metatitanate (Ba 0.98 Sr 0.02 Preparation of high temperature ferroelectrics 100g of titanium oxide, 110g of barium carbonate, and 0.05g of strontium carbonate were added to a ball mill and dry-mixed for 3 hours. 17-88PVA (1.5% by weight of the titanium oxide, barium carbonate, and strontium carbonate mixture) was then added as a first binder. The mixture was pressed into 10mm diameter discs at a pressure of 120 MPa. The discs were placed in an air sintering furnace, sintered at 1285°C, and then held at that temperature for 10 hours to obtain a preform of a high-temperature ferroelectric barium metatitanate. The preform was ball-milled to a particle size of less than 0.5µm, completing the preparation of the high-temperature ferroelectric barium metatitanate.

[0053] Step 3. Casting substrate preparation Ethanol is added to a mixed powder of a capacitor ceramic matrix and a high-temperature ferroelectric barium strontium metatitanate. Ethanol is used as the solvent for the tape casting slurry. PVB is then added as a second binder, a dispersant, and a plasticizer to form the tape casting slurry. The mixed powder of the capacitor ceramic matrix and the high-temperature ferroelectric barium strontium metatitanate accounts for 60g, ethanol accounts for 45g, and PVB accounts for 5g. The dispersant is S85, which accounts for 0.6% of the mass of the tape casting slurry. The plasticizer is DBP, which accounts for 15% of the mass of the tape casting slurry.

[0054] The mass of the barium strontium metatitanate high-temperature ferroelectric is 6% of the mass of the mixed powder of the capacitor ceramic matrix and the barium strontium metatitanate high-temperature ferroelectric.

[0055] The calcium strontium zirconate titanate and barium strontium metatitanate powders used for tape casting have a particle size of less than 0.8 μm, and the slurry viscosity is 7000 mp·s. A 1mm thick sheet is cast on a tape casting machine, then stacked into 10 sheets. This is then pressed into a 9mm sheet using an isostatic press at 20 MPa. A nickel paste is then screen-printed onto the sheet to a thickness of 9mm.

[0056] Step 4. Fabrication of layered high-voltage capacitors 9mm thin sheets, screen-printed with nickel paste, were manually stacked in four layers and pressed into blocks using an isostatic press at 120 MPa. Sintering at 1300°C in an atmosphere of 95% nitrogen and 5% hydrogen resulted in a layered high-voltage capacitor.

[0057] Example 4: A method for preparing a high-voltage capacitor comprises the following steps: Step 1. Prepare capacitor ceramic matrix by yttrium phosphorus modified calcium strontium zirconate titanate powder Calcium strontium zirconate titanate powder is Ca 0.4 Sr 0.6 (Ti 0.2 Zr 0.8 )O3.

[0058] 1 g of yttrium trioxide and 0.6 g of lithium phosphate were added to 100 g of calcium strontium zirconate titanate powder and mixed evenly to prepare a capacitor ceramic matrix.

[0059] Step 2. Barium strontium metatitanate (Ba 0.98 Sr 0.02 Preparation of high temperature ferroelectrics 100g of titanium oxide, 110g of barium carbonate, and 0.05g of strontium carbonate were added to a ball mill and dry-mixed for 3 hours. 17-88PVA (1.5% by weight of the titanium oxide, barium carbonate, and strontium carbonate mixture) was then added as a first binder. The mixture was pressed into 8mm diameter discs at a pressure of 120 MPa. The discs were placed in an air sintering furnace, sintered at 1285°C, and then held at that temperature for 10 hours to obtain a preform of a high-temperature ferroelectric barium metatitanate. The preform was ball-milled to a particle size of less than 0.5µm, completing the preparation of the high-temperature ferroelectric barium metatitanate.

[0060] Step 3. Casting substrate preparation Ethanol is added to a mixed powder of a capacitor ceramic matrix and a high-temperature ferroelectric barium strontium metatitanate. Ethanol is used as the solvent for the tape casting slurry. PVB is then added as a second binder, a dispersant, and a plasticizer to form the tape casting slurry. The mixed powder of the capacitor ceramic matrix and the high-temperature ferroelectric barium strontium metatitanate accounts for 60g, ethanol accounts for 45g, and PVB accounts for 5g. The dispersant is S85, which accounts for 0.6% of the mass of the tape casting slurry. The plasticizer is DBP, which accounts for 15% of the mass of the tape casting slurry.

[0061] The mass of the barium strontium metatitanate high-temperature ferroelectric is 9% of the mass of the mixed powder of the capacitor ceramic matrix and the barium strontium metatitanate high-temperature ferroelectric.

[0062] The calcium strontium zirconate titanate and barium strontium metatitanate powders used for tape casting have a particle size of less than 0.8 μm, and the slurry viscosity is 7000 mp·s. A 1mm thick sheet is cast on a tape casting machine, then stacked into 7 sheets. This is then pressed into a 9mm sheet using an isostatic press at 20 MPa. A nickel paste is then screen-printed onto the sheet to a thickness of 10 mm.

[0063] Step 4. Fabrication of layered high-voltage capacitors 10mm thin sheets, screen-printed with nickel paste, were manually stacked in three layers and pressed into blocks using an isostatic press at 120 MPa. Sintering at 1150°C in an atmosphere of 95% nitrogen and 5% hydrogen resulted in a layered high-voltage capacitor.

[0064] Example 5: A method for preparing a high-voltage capacitor comprises the following steps: Step 1. Prepare capacitor ceramic matrix by yttrium phosphorus modified calcium strontium zirconate titanate powder Calcium strontium zirconate titanate powder is Ca 0.4 Sr 0.6 (Ti 0.2 Zr 0.8 )O3.

[0065] 1 g of yttrium trioxide and 0.6 g of lithium phosphate were added to 100 g of calcium strontium zirconate titanate powder and mixed evenly to prepare a capacitor ceramic matrix.

[0066] Step 2. Barium strontium metatitanate (Ba 0.98 Sr 0.02 Preparation of high temperature ferroelectrics 100g of titanium oxide, 110g of barium carbonate, and 0.05g of strontium carbonate were added to a ball mill and dry-mixed for 3 hours. 17-88PVA (1.5% by weight of the titanium oxide, barium carbonate, and strontium carbonate mixture) was then added as a first binder. The mixture was pressed into a 9mm diameter disc at 120 MPa. The disc was placed in an air sintering furnace, sintered at 1285°C, and then held at that temperature for 10 hours to obtain a preform of a high-temperature ferroelectric barium metatitanate. The preform was ball-milled to a particle size of less than 0.5µm, completing the preparation of the high-temperature ferroelectric barium metatitanate.

[0067] Step 3. Casting substrate preparation Ethanol is added to a mixed powder of a capacitor ceramic matrix and a high-temperature ferroelectric barium strontium metatitanate. Ethanol is used as the solvent for the tape casting slurry. PVB is then added as a second binder, a dispersant, and a plasticizer to form the tape casting slurry. The mixed powder of the capacitor ceramic matrix and the high-temperature ferroelectric barium strontium metatitanate accounts for 60g, ethanol accounts for 45g, and PVB accounts for 5g. The dispersant is S85, which accounts for 0.6% of the mass of the tape casting slurry. The plasticizer is DBP, which accounts for 15% of the mass of the tape casting slurry.

[0068] The mass of the barium strontium metatitanate high-temperature ferroelectric is 12% of the mass of the mixed powder of the capacitor ceramic matrix and the barium strontium metatitanate high-temperature ferroelectric.

[0069] The calcium strontium zirconate titanate and barium strontium metatitanate powders used for tape casting have a particle size of less than 0.8 μm, and the slurry viscosity is 6800 mp·s. A 1mm thick sheet is cast on a tape casting machine, then stacked into seven sheets. The sheets are then pressed into 8mm sheets using an isostatic press at 20 MPa. Nickel paste is then screen-printed onto the sheets to a thickness of 6mm.

[0070] Step 4. Fabrication of layered high-voltage capacitors Four layers of 6mm nickel-screened sheets were manually stacked and pressed into blocks using an isostatic press at 120 MPa. The blocks were then sintered at 1150°C in an atmosphere of 95% nitrogen and 5% hydrogen to create a layered high-voltage capacitor.

[0071] The test results of high-voltage capacitors prepared in Examples 1 to 5 of the present invention by mixing 1%, 3%, 6%, 9%, and 12% of barium strontium metatitanate high-temperature ferroelectric into the capacitor ceramic matrix are shown in Table 1: Table 1 High voltage capacitor test results

[0072] As can be seen from Table 1, the high-voltage capacitor prepared by the preparation method of the present invention meets the power frequency withstand voltage, partial discharge, lightning impulse, high-voltage capacitance and pole accuracy requirements of the primary and secondary fusion poles.

[0073] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for preparing a high-voltage capacitor, characterized in that: include: Yttrium trioxide and lithium phosphate are added to calcium strontium zirconate titanate powder and mixed evenly to prepare a capacitor ceramic matrix; Titanium oxide, barium carbonate and strontium carbonate are dry-mixed uniformly, a first binder is added, the mixture is pressed into a disc, and sintered to obtain a barium strontium metatitanate high-temperature ferroelectric; Adding ethanol as a solvent to a mixed powder of a capacitor ceramic matrix and barium strontium metatitanate high-temperature ferroelectric, then adding a second binder, a dispersant and a plasticizer to prepare a casting slurry, casting a casting sheet, and laminating and pressing it into a sheet; Nickel paste is screen-printed on the thin sheets, which are then stacked and pressed into blocks. They are then sintered in an atmosphere of 95% nitrogen and 5% hydrogen to obtain layered high-voltage capacitors.

2. The method for preparing a high-voltage capacitor according to claim 1, wherein: The calcium strontium zirconate titanate powder is Ca y Sr 1-y (Ti x Zr 1-x )O3, where 0 <y<0.5,0<x<0.3; The barium strontium metatitanate is Ba 1-m Sr m Ti2O5, of which 0 <m<0.1。 3. The method for preparing a high-voltage capacitor according to claim 1, wherein: The mass of the yttrium oxide is 0.1% to 1% of the mass of the calcium strontium zirconate titanate powder, and the mass of the lithium phosphate is 0.5% to 1.5% of the mass of the calcium strontium zirconate titanate powder.

4. The method for preparing a high-voltage capacitor according to claim 1, wherein: The mass of the titanium oxide is 40% to 55% of the mass of the mixture of titanium oxide, barium carbonate and strontium carbonate, the mass of the barium carbonate is 45% to 60% of the mass of the mixture of titanium oxide, barium carbonate and strontium carbonate, and the mass of the strontium carbonate is 0.01% to 1% of the mass of the mixture of titanium oxide, barium carbonate and strontium carbonate.

5. The method for preparing a high-voltage capacitor according to claim 1, wherein: The first binder is 17-88 PVA, and the mass of the first binder is 1% to 1.5% of the mass of the mixture of titanium oxide, barium carbonate and strontium carbonate.

6. The method for preparing a high-voltage capacitor according to claim 1, wherein: The pressing pressure of the disc is 120 MPa, the sintering temperature of the disc is 1285° C., and the holding time is 10 h.

7. The method for preparing a high-voltage capacitor according to claim 1, wherein: The mass of the capacitor ceramic matrix and the barium strontium metatitanate high-temperature ferroelectric mixed powder is 40% to 60% of the mass of the casting slurry, the mass of the ethanol is 30% to 35% of the mass of the casting slurry, the second binder is PVB, the mass of the second binder is 3% to 5% of the mass of the casting slurry, the dispersant is sorbitan trioleate, the mass of the dispersant is 0.1% to 0.6% of the mass of the casting slurry dry powder, and the plasticizer is dibutyl phthalate, the mass of the plasticizer is 5% to 20% of the mass of the second binder; The mass of the barium strontium metatitanate high-temperature ferroelectric is 1% to 12% of the mass of the mixed powder of the capacitor ceramic matrix and the barium strontium metatitanate high-temperature ferroelectric.

8. The method for preparing a high-voltage capacitor according to claim 1, wherein: The pressing pressure of the sheet is 20 MPa, and the thickness of the screen-printed nickel paste on the sheet is 5 to 10 mm; The pressing pressure of the block is 120 MPa, and the sintering temperature of the block is 1150-1300°C.

9. A high-voltage capacitor manufactured by the method according to any one of claims 1 to 8.

10. A primary and secondary fusion pole, characterized in that: Made from the high-voltage capacitor described in claim 9.

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