Preparation method of barium titanate-based thick-film ceramic with high breakdown field, ceramic and electrode
The high breakdown field barium titanate-based thick film ceramics are prepared by casting method, which solves the problem of easy breakdown of lead-free ceramic energy storage capacitors under high electric fields, and realizes the feasibility of high breakdown electric fields and large-scale production, which is suitable for micro devices.
Patent Information
- Application Number
- CN202510584967.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-08
- Publication Date
- 2025-08-15
AI Technical Summary
Existing lead-free ceramic energy storage capacitors are prone to breakdown under high electric fields, and the thickness and size limitations lead to low yield, difficulty in large-scale production, and poor uniformity and consistency, which affects their performance stability.
A high-breakdown field barium titanate-based thick film ceramic was prepared by casting method. Through multiple ball milling and sintering processes, thick film ceramics with uniform thickness and consistent composition were formed. Combined with screen printing of silver electrodes, the breakdown electric field strength was improved.
It achieves a high breakdown electric field strength, up to 140kV/cm, suitable for micro-device applications, reduce production costs, and is suitable for large-scale production.
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Figure CN120483709A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of thick film ceramics, and in particular to a preparation method of a high breakdown field barium titanate-based thick film ceramic, and the ceramic and an electrode. Background Art
[0002] Ceramic energy storage capacitors are widely used in advanced pulse power technologies due to their high power density, fast discharge rate, strong mechanical properties, high temperature resistance, corrosion resistance, and long service life. With the development of electronic technology, the performance and functionality requirements of electronic components and assemblies are becoming increasingly demanding, while the size of products is being reduced. Therefore, the development of lead-free ceramic energy storage capacitors with high energy storage density is of great practical and strategic significance. Currently, the high energy storage density of lead-free ceramic energy storage capacitors often requires very high electric field strengths, which limits their practical application.
[0003] The existing technology has the following defects: thickness and size limitations. Bulk piezoelectric ceramics are relatively thick. In order to increase their breakdown electric field, ultra-thin ceramic sheets (such as tens to hundreds of microns) are usually prepared. They are very easy to break during the thinning process and have a low yield rate. The thickness of ceramic sheets prepared by the casting method is very thin (even up to several microns), which is suitable for miniaturized and integrated electronic devices such as sensors and actuators. In terms of uniformity and consistency, bulk piezoelectric ceramics may have problems such as uneven sintering and uneven internal stress distribution during the preparation process. The uniformity and consistency of bulk ceramics are poor, affecting the stability of their performance. Large-scale preparation is difficult. Bulk piezoelectric ceramics are prone to introducing impurities and other large defects. The presence of defects under high electric fields will cause the sample to break down very easily. In addition, the reproducibility of ceramic bulk samples is poor, which is not conducive to large-scale production.
[0004] The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Summary of the Invention
[0005] The present invention provides a preparation method of high breakdown field barium titanate-based thick film ceramics, ceramics and electrodes, which significantly improve the breakdown electric field, can form thick film ceramics with uniform thickness and consistent composition, and can be prepared on a large scale.
[0006] A method for preparing a high breakdown field barium titanate-based thick film ceramic comprises: Step S100, according to the chemical formula (Ba 1-x A x )(B y Ti 1-y)O3 atomic percentage, weighing the raw materials, mixing them and performing a first ball milling, wherein x is 0.0 to 1.0, y is 0.0 to 1.0, A represents Ca, Sr or Cr; and B represents Zr, Sn or Hf; drying the ball-milled raw materials to obtain raw material powder; Step S200: compacting the raw material powder and pre-calcining to obtain a block, crushing the block and adding deionized water for a second ball milling, and drying to obtain a synthetic powder; Step S300: mixing the organic solvent and the synthetic powder and performing a third ball milling to obtain a slurry; Step S400: Pour the slurry evenly onto the film belt of the casting machine and level it with a scraper; Step S500, drying to obtain a green ceramic tape of high breakdown field barium titanate-based thick film ceramic; Step S600: Cut the green porcelain tape into green porcelain sheets, place the green porcelain sheets into a muffle furnace and sinter them to obtain high breakdown field barium titanate-based thick film ceramics with a thickness of 30-100 μm and a high breakdown field of 100 kV / cm-140 kV / cm.
[0007] In the method for preparing a high breakdown field barium titanate-based thick film ceramic, in step S100, the first ball milling is wet ball milling, anhydrous ethanol and agate balls are used as the medium, and the raw materials and anhydrous ethanol are mixed in a mass percentage ratio of 1:1 and ball milled for 6-8 hours.
[0008] In the method for preparing a high breakdown field barium titanate-based thick film ceramic, in step S200, the pre-firing temperature is 1150-1250°C, the pre-firing time is 2-3.5 hours, the pre-firing heating rate is 3-4°C / min, and the product after pre-firing is set to cool at a rate of 3°C / min to 300°C, then cooled to room temperature with the furnace, and then crushed.
[0009] In the method for preparing high breakdown field barium titanate-based thick film ceramics, the second ball milling includes wet ball milling for 8-12 hours. After the ball milling is completed, the powder is washed out with anhydrous ethanol and dried to obtain a synthetic powder.
[0010] In the method for preparing high breakdown field barium titanate-based thick film ceramics, in step S300, the organic solvent is an organic base solvent, which includes anhydrous ethanol, a dispersant, a binder and a plasticizer.
[0011] In the method for preparing high breakdown field barium titanate-based thick film ceramics, the third ball milling includes wet ball milling, the ball milling time is 20-24 hours, and the total mass percentage of the organic solvent and the synthetic powder is mixed with the agate ball in a ratio of 1:1.
[0012] In the method for preparing a high breakdown field barium titanate-based thick film ceramic, step S600 includes the following steps: S601, set the heating rate to 1-2°C / min and raise the temperature to 540-560°C, and keep it warm for 8-10 hours; S602, set the heating rate to 2-3°C / min to raise the temperature to 1250-1350°C, keep the temperature for 3-4 hours, set the cooling rate to 3°C / min to 300°C, and then cool to room temperature with the furnace to obtain a high breakdown field barium titanate-based thick film ceramic.
[0013] A high breakdown field barium titanate-based thick film ceramic is prepared by the method.
[0014] An electrode comprises the high breakdown field barium titanate-based thick film ceramic and a conductive metal coated thereon.
[0015] In the electrode, the conductive metal is silver, which is screen-printed on a high-breakdown-field barium titanate-based thick-film ceramic, and then calcined at 800° C. for 30 minutes to obtain a silver electrode.
[0016] Compared with existing technologies, this invention offers the following advantages: The breakdown electric field strength generally exceeds 100 kV / cm, reaching a maximum of 140 kV / cm. Compared to traditional solid-phase reaction sintering, the ceramics produced by the tape casting method have uniform grains, are breakdown-resistant, and have a reduced thickness, making them suitable for use in microdevices. The tape casting method also conserves raw materials, reduces production costs, and is suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Various other advantages and benefits of the present invention will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are intended only to illustrate preferred embodiments and are not to be construed as limiting the present invention. It should be understood that the drawings described below are merely examples of the present invention, and that those skilled in the art will be able to derive other drawings from these drawings without inventive effort. Throughout the drawings, identical reference numerals are used to denote identical components.
[0018] In the attached figure: Figure 1 A schematic diagram of the surface morphology of a high breakdown field barium titanate-based thick film ceramic according to an embodiment of the present invention; Figure 2 Schematic diagram of the PE curve of an embodiment of the present invention.
[0019] The present invention will be further explained below with reference to the accompanying drawings and embodiments. DETAILED DESCRIPTION
[0020] Specific embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although specific embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.
[0021] It should be noted that certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. This specification and claims do not use the difference in nouns as a way to distinguish components, but use the difference in the functions of the components as the criterion for distinction. As mentioned throughout the specification and claims, "including" or "comprising" is an open term, so it should be interpreted as "including but not limited to". The subsequent description of the specification is a preferred embodiment of the present invention, but the description is based on the general principles of the specification and is not intended to limit the scope of the invention. The scope of protection of the present invention shall be as defined in the attached claims.
[0022] To facilitate understanding of the embodiments of the present invention, further explanation will be given below using specific embodiments as examples in conjunction with the accompanying drawings, and the accompanying drawings do not constitute a limitation on the embodiments of the present invention.
[0023] like Figures 1 to 2 As shown, the method for preparing high breakdown field barium titanate-based thick film ceramics includes the following steps: Step S100, according to the chemical formula (Ba 1-x A x )(B y Ti 1-y )O3 atomic percentage, weighing the raw materials, mixing them and performing a first ball milling, wherein x is 0.0 to 1.0, y is 0.0 to 1.0, A represents Ca, Sr or Cr; and B represents Zr, Sn or Hf; drying the ball-milled raw materials to obtain raw material powder; Step S200: compacting the raw material powder and pre-calcining to obtain a block, crushing the block and adding deionized water for a second ball milling, and drying to obtain a synthetic powder; Step S300: mixing the organic solvent and the synthetic powder and performing a third ball milling to obtain a slurry; Step S400: Pour the slurry evenly onto the film belt of the casting machine and level it with a scraper; Step S500, drying to obtain a green ceramic tape of high breakdown field barium titanate-based thick film ceramic; Step S600: Cut the green porcelain tape into green porcelain sheets, place the green porcelain sheets into a muffle furnace and sinter them to obtain high breakdown field barium titanate-based thick film ceramics with a thickness of 30-100 μm and a high breakdown field of 100 kV / cm-140 kV / cm.
[0024] In a preferred embodiment of the method for preparing a high breakdown field barium titanate-based thick film ceramic, in step S100, the first ball milling includes wet ball milling, using anhydrous ethanol and agate balls as the medium, and the raw materials and anhydrous ethanol are mixed in a ratio of 1:1 by mass and ball milled for 6-8 hours.
[0025] In a preferred embodiment of the method for preparing a high breakdown field barium titanate-based thick film ceramic, in step S200, the pre-firing temperature is 1150-1250°C, the pre-firing time is 2-3h, the pre-firing heating rate is 3-4°C / min, and the product after pre-firing is set to cool at a rate of 3°C / min to 300°C, then cooled to room temperature with the furnace, and then crushed.
[0026] In a preferred embodiment of the method for preparing a high breakdown field barium titanate-based thick film ceramic, the second ball milling includes wet ball milling for 8-12 hours. After the ball milling, the powder is washed out with anhydrous ethanol and dried to obtain a synthetic powder.
[0027] In a preferred embodiment of the method for preparing a high breakdown field barium titanate-based thick film ceramic, in step S300, the organic solvent is an organic base solvent, which includes anhydrous ethanol, a dispersant, a binder and a plasticizer.
[0028] In a preferred embodiment of the method for preparing a high breakdown field barium titanate-based thick film ceramic, the third ball milling includes wet ball milling, the ball milling time is 20-24 hours, and the total mass percentage of the organic solvent and the synthetic powder to the agate ball is mixed in a ratio of 1:1.
[0029] In a preferred embodiment of the method for preparing a high breakdown field barium titanate-based thick film ceramic, step S600 includes the following steps: S601, set the heating rate to 1-2°C / min and raise the temperature to 540-560°C, and keep it warm for 8-10 hours; S602, set the heating rate to 2-3°C / min to raise the temperature to 1250-1350°C, keep the temperature for 3-4 hours, set the cooling rate to 3°C / min to 300°C, and then cool to room temperature with the furnace to obtain a high breakdown field barium titanate-based thick film ceramic.
[0030] A high breakdown field barium titanate-based thick film ceramic is prepared by the method.
[0031] An electrode comprises the high breakdown field barium titanate-based thick film ceramic and a conductive metal coated thereon.
[0032] In a preferred embodiment of the electrode, the conductive metal is silver, which is screen-printed on a high breakdown field barium titanate-based thick film ceramic, and the silver is sintered at 800° C. for 30 minutes to obtain a silver electrode.
[0033] Example 1 BaCO3 with a purity of 0.99, TiO2 with a purity of 0.99 and ZrO2 with a purity of 0.99 were mixed according to the chemical composition of Ba(Zr 0.3 Ti 0.7 )O3 was mixed and wet-milled to obtain a raw material powder. The raw material powder was mixed in a ratio of 1:1 with deionized water and agate balls as the medium for 6 hours.
[0034] The raw powder was compacted in an alumina crucible and calcined at a heating rate of 3°C / min. The crucible was covered and calcined at 1150°C for 3 hours. The temperature was then cooled at a rate of 3°C / min to 300°C. The crucible was then furnace-cooled to room temperature, pulverized, wet-milled twice, and dried to obtain the synthesized powder.
[0035] Heat and mix anhydrous ethanol, dispersant, binder, and plasticizer, and add them together with the synthetic powder into a ball mill. Use wet ball milling for 20 hours.
[0036] After the ball milling is completed, the slurry is immediately taken out and evenly poured onto the film belt of the casting machine, and then scraped flat with a scraper. After drying, it is removed from the PET film belt and cut into suitable shapes.
[0037] The cut raw ceramic pieces were placed flat on a zirconium plate and placed in a muffle furnace. The heating rate was set to 1°C / min and the temperature was raised to 540°C, and kept warm for 8 hours. The heating rate was then set to 2°C / min and the temperature was raised to 1250°C. After keeping warm for 3 hours, the cooling rate was set to 3°C / min to 300°C. The ceramic pieces were then cooled to room temperature in the furnace to obtain high breakdown field BZT thick film ceramics.
[0038] Example 2 BaCO3 with a purity of 0.99, TiO2 with a purity of 0.99 and ZrO2 with a purity of 0.99 were mixed according to the chemical composition of Ba(Zr 0.2 Ti 0.8 )O3 was mixed and wet-milled to obtain a raw material powder. The raw material powder was mixed in a ratio of 1:1 with deionized water and agate balls as the medium for 7 hours.
[0039] The raw material powder was compacted in an alumina crucible, covered, and calcined at 1200°C for 2.5 hours. The temperature was ramped up at a rate of 3.5°C / min. The temperature was then cooled down to 300°C at a rate of 3°C / min. The product was then furnace-cooled to room temperature, pulverized, wet-milled twice, and dried to obtain a synthetic powder.
[0040] Heat and mix anhydrous ethanol, dispersant, binder, and plasticizer, and add them together with the synthetic powder into a ball mill. Use wet ball milling for 22 hours.
[0041] After the ball milling is completed, the slurry is immediately taken out and evenly poured onto the film belt of the casting machine, and then scraped flat with a scraper. After drying, it is removed from the PET film belt and cut into suitable shapes.
[0042] The cut raw ceramic pieces were placed flat on a zirconium plate and placed in a muffle furnace. The heating rate was set to 1°C / min and the temperature was raised to 550°C, which was kept for 9 hours. The heating rate was then set to 2.5°C / min and the temperature was raised to 1300°C. After keeping the temperature for 3.5 hours, the cooling rate was set to 3°C / min and the temperature was lowered to 300°C. The ceramics were then cooled to room temperature in the furnace to obtain high breakdown field BZT thick film ceramics.
[0043] Example 3 BaCO3 with a purity of 0.99, TiO2 with a purity of 0.99 and ZrO2 with a purity of 0.99 were mixed according to the chemical composition of Ba(Zr 0.1 Ti 0.9 )O3 was mixed and wet-milled to obtain a raw material powder. The raw material powder was mixed in a ratio of 1:1 with deionized water and agate balls as the medium for 8 hours.
[0044] The raw material powder was compacted in an alumina crucible, covered, and calcined at 1250°C for 2 hours. The temperature was ramped up at a rate of 4°C / min. The temperature was then cooled down at a rate of 3°C / min to 300°C. The product was then furnace-cooled to room temperature and pulverized. After a second wet ball milling process for 12 hours, the product was dried to obtain the synthesized powder.
[0045] Heat and mix anhydrous ethanol, dispersant, binder, and plasticizer, and add them together with the synthetic powder into a ball mill. Use wet ball milling for 24 hours.
[0046] After the ball milling is completed, the slurry is immediately taken out and evenly poured onto the film belt of the casting machine, and then scraped flat with a scraper. After drying, it is removed from the PET film belt and cut into suitable shapes.
[0047] The cut raw ceramic pieces were placed flat on a zirconium plate and placed in a muffle furnace. The heating rate was set to 1°C / min and the temperature was raised to 560°C, which was kept for 10 hours. The heating rate was then set to 3°C / min and the temperature was raised to 1300°C. After keeping the temperature for 4 hours, the cooling rate was set to 3°C / min and the temperature was lowered to 300°C. The ceramic was then cooled to room temperature in the furnace to obtain a high breakdown field BZT thick film ceramic.
[0048] Example 2 is (Ba 1-x A x )(B y Ti 1-y )O3 wherein B=Zr, x= 0.0, y=0.2 is a preferred embodiment, because a more appropriate primary ball milling time is selected, the raw materials are evenly mixed; the pre-firing temperature and time are appropriate, so that BZT is fully reacted into porcelain during the pre-firing process, and is fully ground in the subsequent secondary ball milling process, providing a fine and uniform powder for the casting process. Through the above-mentioned heat treatment and ball milling method mentioned in the specific implementation process, it is ensured that the casting operation can obtain a raw porcelain tape with a smooth surface and uniform thickness, and the thickness can be controlled within 30~100μm. In addition, the specific implementation process can also ensure that the ceramic thick film finally sintered has uniform grains, few defects, and is resistant to breakdown.
[0049] Figure 1 This is the surface morphology of the high breakdown field barium titanate-based thick film ceramic of a preferred embodiment 2 of the present invention. It can be seen that the grains on the ceramic surface are evenly distributed without defects such as pores.
[0050] Silver electrodes were obtained by screen-printing silver on two parallel surfaces of a sintered high-breakdown-field barium titanate-based thick-film ceramic. The silver was then sintered at 800°C for 30 minutes. Hysteresis loop measurements revealed that the BZT thick film remained relatively stable at a breakdown electric field of 100 kV / cm, and could reach a maximum breakdown electric field of 140 kV / cm.
[0051] Figure 2 This is the hysteresis loop (PE curve) of the high breakdown field barium titanate-based thick film ceramic according to a preferred embodiment 2 of the present invention.
[0052] Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to the above-mentioned specific embodiments and application fields. The above-mentioned specific embodiments are merely illustrative and instructive, and are not restrictive. A person skilled in the art, guided by this specification and without departing from the scope of protection of the claims of the present invention, may also devise various forms, all of which fall within the scope of protection of the present invention.
Claims
1. A method for preparing high breakdown field barium titanate-based thick film ceramics, characterized in that: The steps include: Step S100, according to the chemical formula (Ba 1-x A x )(B y Ti 1-y )O3 atomic percentage, weighing the raw materials, mixing them and performing the first ball milling, wherein x is 0.0 to 1.0, y is 0.0 to 1.0, A represents Ca, Sr or Cr; B represents Zr, Sn or Hf; drying the ball-milled raw materials to obtain raw material powder; Step S200: compacting the raw material powder and pre-calcining to obtain a block, crushing the block and adding deionized water for a second ball milling, and drying to obtain a synthetic powder; Step S300: mixing the organic solvent and the synthetic powder and performing a third ball milling to obtain a slurry; Step S400: Pour the slurry evenly onto the film belt of the casting machine and level it with a scraper; Step S500, drying to obtain a green ceramic tape of high breakdown field barium titanate-based thick film ceramic; Step S600: Cut the green porcelain tape into green porcelain sheets, place the green porcelain sheets into a muffle furnace and sinter them to obtain high breakdown field barium titanate-based thick film ceramics with a thickness of 30-100 μm and a high breakdown field of 100 kV / cm-140 kV / cm.
2. The method for preparing a high breakdown field barium titanate-based thick film ceramic according to claim 1, characterized in that: Preferably, in step S100, the first ball milling is wet ball milling, with anhydrous ethanol and agate balls as the medium, and the raw materials and anhydrous ethanol are mixed in a ratio of 1:1 by mass and ball milled for 6-8 hours.
3. The method for preparing a high breakdown field barium titanate-based thick film ceramic according to claim 1, characterized in that: In step S200, the pre-firing temperature is 1150-1250°C, the pre-firing time is 2-3.5h, the pre-firing heating rate is 3-4°C / min, and the product after pre-firing is set to cool at a rate of 3°C / min to 300°C, then cooled to room temperature with the furnace, and then crushed.
4. The method for preparing a high breakdown field barium titanate-based thick film ceramic according to claim 1, characterized in that: The second ball milling includes wet ball milling for 8-12 hours. After the ball milling is completed, the powder is washed out with anhydrous ethanol and dried to obtain a synthetic powder.
5. The method for preparing a high breakdown field barium titanate-based thick film ceramic according to claim 1, characterized in that: In step S300 , the organic solvent is an organic base solvent, which includes anhydrous ethanol, a dispersant, a binder, and a plasticizer.
6. The method for preparing a high breakdown field barium titanate-based thick film ceramic according to claim 1, characterized in that: The third ball milling includes wet ball milling, the ball milling time is 20-24 hours, and the total mass percentage of the organic solvent and the synthetic powder to the agate ball is 1:
1.
7. The method for preparing a high breakdown field barium titanate-based thick film ceramic according to claim 1, characterized in that: Step S600 includes the following steps: S601, set the heating rate to 1-2°C / min and raise the temperature to 540-560°C, and keep it warm for 8-10 hours; S602, set the heating rate to 2-3°C / min to raise the temperature to 1250-1350°C, keep the temperature for 3-4 hours, set the cooling rate to 3°C / min to 300°C, and then cool to room temperature with the furnace to obtain a high breakdown field barium titanate-based thick film ceramic.
8. A high breakdown field barium titanate-based thick film ceramic, characterized in that: It is prepared by the method according to any one of claims 1 to 7.
9. An electrode, characterized in that The invention comprises the high breakdown field barium titanate-based thick film ceramic according to claim 8 and a conductive metal coated thereon.
10. An electrode according to claim 9, characterized in that: The conductive metal is silver, which is screen-printed on a high-breakdown-field barium titanate-based thick-film ceramic, and the silver is calcined at 800° C. for 30 minutes to obtain a silver electrode.