A combination wave ceramic capacitor material and preparation method thereof

Abstract

The present invention belongs to the technical field of ceramic capacitor materials, and specifically relates to a combination wave ceramic capacitor material and a preparation method thereof. The preparation method of the ceramic capacitor material provided by the present invention comprises the following steps: mixing barium titanate, yttrium oxide, cerium oxide, manganese oxide, calcium oxide, acidic silica sol and water, ball milling, and drying; grinding and crushing the primary mixture and mixing it with alkaline silica sol and water, ball milling, and drying; grinding and crushing the secondary mixture and performing a first sintering; grinding and crushing the primary sintered material, then adding anhydrous ethanol for ball milling, drying, and grinding and crushing; mixing the ball-milled mixture and a binder, granulating, pressing and forming to obtain a ceramic green body; insulating the ceramic green body, and then performing a second sintering to obtain the ceramic capacitor material. The ceramic capacitor material prepared by the preparation method provided by the present invention can effectively improve the breakdown strength of the material and reduce its dielectric loss.

Description

Technical Field

[0001] The present invention belongs to the technical field of ceramic capacitor materials, and in particular relates to a combination wave ceramic capacitor material and a preparation method thereof. Background Art

[0002] Ceramic capacitors offer excellent voltage resistance and high stability, making them widely used in power equipment, copy and printing equipment, laser equipment, aerospace equipment, and other fields. As the core material of capacitors, ceramic capacitors determine their performance. With technological advancements and the passage of time, capacitors are trending towards miniaturization and ultra-thinness, placing higher demands on the breakdown strength and dielectric loss of ceramic capacitor materials.

[0003] Barium titanate (BaTiO3) has excellent strong dielectric properties and is one of the best choices for preparing ceramic capacitor materials. However, traditional barium titanate-based ceramic capacitor materials have low breakdown strength and large dielectric loss, which is difficult to meet actual production needs. Therefore, it is necessary to improve them. Common improvement methods include using yttrium oxide, calcium oxide, etc. for doping modification, or optimizing the preparation process to achieve the purpose of improving the breakdown voltage of the material and reducing the dielectric loss. For example, the prior art adds sintering aids, such as silicon dioxide, during the material preparation process to prevent the ceramic particles from growing during the sintering process, improve its material density, and then improve the breakdown strength and dielectric loss of the material. However, the prior art generally mixes silicon dioxide powder directly with raw material powders such as barium titanate, and then obtains ceramic capacitor materials through processes such as pressing and sintering. Since the powder is easy to agglomerate, it is easy to cause uneven mixing of the raw materials. Silicon dioxide, as a sintering aid, cannot fully play the role of a sintering aid during the sintering process, resulting in some grains being too large, affecting the breakdown strength and dielectric loss of the final material. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defect that the ceramic capacitor material obtained by directly mixing, pressing and sintering the silicon dioxide sintering aid with barium titanate and other raw material powders in the preparation process of barium titanate-based ceramic capacitor materials has limited improvement in breakdown strength and dielectric loss, and thus provide a combination wave ceramic capacitor material and its preparation method.

[0005] In order to solve the above problems, the present invention provides the following solutions:

[0006] A method for preparing a ceramic capacitor material comprises the following steps:

[0007] 1) barium titanate, yttrium oxide, cerium oxide, manganese oxide, calcium oxide, acidic silica sol and water are mixed, ball-milled and dried to obtain a primary mixture;

[0008] 2) Grinding and crushing the primary mixture, mixing it with alkaline silica sol and water, ball milling it, and drying it to obtain a secondary mixture;

[0009] 3) Grinding and crushing the secondary mixture and then sintering it for the first time to obtain a primary sintered product;

[0010] 4) grinding and pulverizing the primary sintered product, then adding anhydrous ethanol and ball milling the product, drying the product after ball milling, and grinding and pulverizing the product to obtain a ball milled mixture;

[0011] 5) mixing the ball mill mixture and the binder, granulating the mixture, and pressing the mixture to obtain a ceramic green body;

[0012] 6) The ceramic green body is kept warm, and then sintered for a second time to obtain the ceramic capacitor material.

[0013] Preferably, the pH value of the acidic silica sol is 2.5-2.8, and the mass content of silicon dioxide is 28-35%;

[0014] The pH value of the alkaline silica sol is 9.0-9.5, and the mass content of silicon dioxide is 15-20%.

[0015] Preferably, in step 1), the mass ratio of barium titanate, yttrium oxide, cerium oxide, manganese oxide, calcium oxide, acidic silica sol and water is 100:(3-3.1):(2.3-2.5):(0.5-0.8):(2.0-2.2):(1.8-2.0):(100-110).

[0016] Preferably, the first sintering temperature is 1020-1050°C and the sintering time is 3-5h;

[0017] In step 6), the holding temperature is 550-580° C., the holding time is 1-3 hours, the second sintering temperature is 1200-1250° C., and the sintering time is 2.5-3 hours.

[0018] Preferably, the average particle size of barium titanate is 200-250 nm.

[0019] Preferably, in step 1), the ball milling speed is 450-500 rpm, the ball milling time is 15-20 h, the drying temperature is 100-105° C., and the drying time is 10-15 h;

[0020] In step 2), the ball milling speed is 450-500 rpm, the ball milling time is 15-20 h, the drying temperature is 100-105° C., and the drying time is 10-15 h;

[0021] In step 4), the ball milling speed is 600-650 rpm, the ball milling time is 15-20 h, the drying temperature is 80-100° C., and the drying time is 5-10 h.

[0022] Preferably, the amount of water added in step 2) is 1-1.1 times the mass of barium titanate;

[0023] The mass ratio of barium titanate to alkaline silica sol is 100:(0.8-1).

[0024] Preferably, the amount of anhydrous ethanol added is 0.8-1.0 times the mass of the primary sintered material;

[0025] After grinding and pulverizing in step 4), the product is further screened through a 150-200 mesh sieve.

[0026] Preferably, the binder is selected from a polyvinyl alcohol solution, the mass concentration of the polyvinyl alcohol solution is 10-14%, and the amount of the polyvinyl alcohol solution added is 18-22% of the mass of the ball-milled mixture;

[0027] The pressure in the compression molding step in step 5) is 200-240 MPa.

[0028] The present invention also provides a combination wave ceramic capacitor material, which is prepared by the above-mentioned preparation method. The ceramic capacitor material prepared by the present invention has good stability and high breakdown strength, and can be used as a combination wave ceramic capacitor material.

[0029] The technical solution of the present invention has the following advantages:

[0030] The present invention provides a method for preparing a ceramic capacitor material. The method comprises the following steps: firstly, barium titanate, yttrium oxide, cerium oxide, manganese oxide, calcium oxide, acidic silica sol and water are mixed, ball-milled and dried to obtain a primary mixture; then, the primary mixture is ground and crushed, mixed with alkaline silica sol and water, ball-milled and dried to obtain a secondary mixture; then, the secondary mixture is ground and crushed, and then sintered for a first time; the primary sintered product is ground and crushed, anhydrous ethanol is added, ball-milled and dried; the ball-milled mixture is mixed with a binder, granulated and pressed to obtain a ceramic green body; and the ceramic green body is heat-insulated and sintered for a second time to obtain the ceramic capacitor material. The present invention adopts a two-mixing and two-sintering process in the preparation process of ceramic capacitor materials, wherein acidic silica sol is used in the first mixing process instead of silicon dioxide, and the sensitivity of barium titanate to acid is utilized to make the barium titanate more evenly dispersed in the acidic silica sol solution. The obtained mixture is then mixed with alkaline silica sol and ball-milled, and the acid on the surface of the mixture is neutralized while further dispersing barium titanate and other raw materials to make the mixing more even. After that, after sintering and other processes, silicon dioxide can effectively promote the generation of a liquid phase, so that the liquid phase can fully wrap the grains, prevent excessive growth of the grains, improve the density of the material, effectively improve the breakdown strength of the material, and reduce dielectric loss. DETAILED DESCRIPTION

[0031] The following examples are provided for further understanding of the present invention and are not intended to limit the best mode of implementation and the scope of protection of the present invention.

[0032] Any experimental steps or conditions not specified in the following embodiments of the present invention may be carried out according to conventional experimental steps and conditions used in existing literature in the field. Reagents or instruments used without specifying the manufacturer are all commercially available conventional reagents or instruments.

[0033] Example 1

[0034] This embodiment provides a method for preparing a ceramic capacitor material, comprising the following steps:

[0035] 1) 100 g of barium titanate (average particle size 230 nm), 3 g of yttrium oxide, 2.5 g of cerium oxide, 0.8 g of manganese oxide, 2.0 g of calcium oxide, 1.8 g of acidic silica sol (pH 2.8, silica content 30% by mass), and 100 g of water were mixed, ball-milled at 500 rpm for 15 h, and then dried at 100° C. for 10 h to obtain a primary mixture;

[0036] 2) The primary mixture was ground and pulverized, mixed with 1 g of alkaline silica sol (pH 9.2, silica content 18%) and 100 g of water, and ball-milled at 500 rpm for 15 h, followed by drying at 100° C. for 10 h to obtain a secondary mixture;

[0037] 3) Grinding and crushing the secondary mixture, and sintering at 1050°C for 3.5 hours to obtain a primary sintered material;

[0038] 4) Grinding the primary sintered material, then adding anhydrous ethanol (the amount of anhydrous ethanol added is 0.8 times the mass of the primary sintered material) and ball milling at a ball milling speed of 600 rpm for 15 hours. After ball milling, drying (drying temperature of 80°C for 5 hours), grinding and sieving through a 150-mesh sieve to obtain a ball-milled mixture;

[0039] 5) mixing the ball-milled mixture with a polyvinyl alcohol solution (the mass concentration of the polyvinyl alcohol solution is 10%, and the amount of the polyvinyl alcohol solution added is 18% of the mass of the ball-milled mixture), granulating the mixture, and pressing the mixture at 230 MPa to obtain a ceramic green body;

[0040] 6) The ceramic green body was kept at 550° C. for 1 hour, and then sintered at 1200° C. for 2.5 hours to obtain the ceramic capacitor material.

[0041] Example 2

[0042] This embodiment provides a method for preparing a ceramic capacitor material, comprising the following steps:

[0043] 1) 100 g of barium titanate (average particle size 230 nm), 3.1 g of yttrium oxide, 2.3 g of cerium oxide, 0.5 g of manganese oxide, 2.2 g of calcium oxide, 2.0 g of acidic silica sol (pH 2.8, silica content 30% by mass), and 110 g of water were mixed, ball-milled at 450 rpm for 18 hours, and then dried at 100° C. for 10 hours to obtain a primary mixture;

[0044] 2) The primary mixture was ground and mixed with 0.8 g of alkaline silica sol (pH 9.2, silica content 18%) and 110 g of water, and ball-milled at 450 rpm for 18 h, followed by drying at 100° C. for 10 h to obtain a secondary mixture;

[0045] 3) Grinding and crushing the secondary mixture, and sintering at 1050°C for 4.5 hours to obtain a primary sintered material;

[0046] 4) Grinding the primary sintered material, then adding anhydrous ethanol (the amount of anhydrous ethanol added is 1.0 times the mass of the primary sintered material) and ball milling at a ball milling speed of 650 rpm for 15 hours. After ball milling, drying (drying temperature of 80°C for 5 hours), grinding and sieving through a 150-mesh sieve to obtain a ball-milled mixture;

[0047] 5) mixing the ball-milled mixture with a polyvinyl alcohol solution (the mass concentration of the polyvinyl alcohol solution is 10%, and the amount of the polyvinyl alcohol solution added is 18% of the mass of the ball-milled mixture), granulating the mixture, and pressing the mixture at 230 MPa to obtain a ceramic green body;

[0048] 6) The ceramic green body was kept at 550° C. for 1 hour, and then sintered at 1200° C. for 3.0 hours to obtain the ceramic capacitor material.

[0049] Comparative Example 1

[0050] This comparative example provides a method for preparing a ceramic capacitor material, comprising the following steps:

[0051] 1) 100 g of barium titanate (average particle size of 230 nm), 3 g of yttrium oxide, 2.5 g of cerium oxide, 0.8 g of manganese oxide, 2.0 g of calcium oxide, 0.54 g of silicon dioxide, and 100 g of water were mixed, ball-milled at a speed of 500 rpm for 15 h, and then dried at a drying temperature of 100° C. for 10 h to obtain a primary mixture;

[0052] 2) The primary mixture was ground and pulverized, mixed with 0.18 g of silica and 100 g of water, and ball-milled at a speed of 500 rpm for 15 h, and then dried at a drying temperature of 100° C. for 10 h to obtain a secondary mixture;

[0053] 3) Grinding and crushing the secondary mixture, and sintering at 1050°C for 3.5 hours to obtain a primary sintered material;

[0054] 4) Grinding the primary sintered material, then adding anhydrous ethanol (the amount of anhydrous ethanol added is 0.8 times the mass of the primary sintered material) and ball milling at a ball milling speed of 600 rpm for 15 hours. After ball milling, drying (drying temperature of 80°C for 5 hours), grinding and sieving through a 150-mesh sieve to obtain a ball-milled mixture;

[0055] 5) mixing the ball-milled mixture with a polyvinyl alcohol solution (the mass concentration of the polyvinyl alcohol solution is 10%, and the amount of the polyvinyl alcohol solution added is 18% of the mass of the ball-milled mixture), granulating the mixture, and pressing the mixture at 230 MPa to obtain a ceramic green body;

[0056] 6) The ceramic green body was kept at 550° C. for 1 hour, and then sintered at 1200° C. for 2.5 hours to obtain the ceramic capacitor material.

[0057] Comparative Example 2

[0058] This comparative example provides a method for preparing a ceramic capacitor material, which differs from Example 1 in that in step 1), 1.8 g of acidic silica sol is replaced with 3 g of alkaline silica sol (pH 9.2, silicon dioxide mass content 18%).

[0059] Comparative Example 3

[0060] This comparative example provides a method for preparing a ceramic capacitor material, comprising the following steps:

[0061] 1) 100 g of barium titanate (average particle size of 230 nm), 3 g of yttrium oxide, 2.5 g of cerium oxide, 0.8 g of manganese oxide, 2.0 g of calcium oxide, 1 g of alkaline silica sol (pH 9.2, silica content of 18% by mass), and 100 g of water were mixed, ball-milled at 500 rpm for 15 h, and then dried at 100° C. for 10 h to obtain a primary mixture;

[0062] 2) The primary mixture was ground and pulverized, mixed with 1.8 g of acidic silica sol (pH 2.8, silica content 30% by mass) and 100 g of water, and ball-milled at 500 rpm for 15 h, followed by drying at 100° C. for 10 h to obtain a secondary mixture;

[0063] 3) Grinding and crushing the secondary mixture, and sintering at 1050°C for 3.5 hours to obtain a primary sintered material;

[0064] 4) Grinding the primary sintered material, then adding anhydrous ethanol (the amount of anhydrous ethanol added is 0.8 times the mass of the primary sintered material) and ball milling at a ball milling speed of 600 rpm for 15 hours. After ball milling, drying (drying temperature of 80°C for 5 hours), grinding and sieving through a 150-mesh sieve to obtain a ball-milled mixture;

[0065] 5) mixing the ball-milled mixture with a polyvinyl alcohol solution (the mass concentration of the polyvinyl alcohol solution is 10%, and the amount of the polyvinyl alcohol solution added is 18% of the mass of the ball-milled mixture), granulating the mixture, and pressing the mixture at 230 MPa to obtain a ceramic green body;

[0066] 6) The ceramic green body was kept at 550° C. for 1 hour, and then sintered at 1200° C. for 2.5 hours to obtain the ceramic capacitor material.

[0067] Test Example 1

[0068] The performance of the ceramic capacitor materials prepared in the above examples and comparative examples was tested (25° C., 1 KHz). The test results are shown in Table 1.

[0069] Table 1

[0070]

[0071] Obviously, for those skilled in the art, other variations can be made based on the above embodiments, and the obvious variations thus brought about are still within the scope of protection of the present invention.

Claims

1. A method for preparing a ceramic capacitor material, characterized in that: The steps include: 1) barium titanate, yttrium oxide, cerium oxide, manganese oxide, calcium oxide, acidic silica sol and water are mixed, ball-milled and dried to obtain a primary mixture; 2) Grind the primary mixture, mix it with alkaline silica sol and water, ball mill it, and dry it to obtain a secondary mixture; 3) Grinding and crushing the secondary mixture and then sintering it for the first time to obtain a primary sintered material; 4) Grinding the primary sintered material into powder, then adding anhydrous ethanol to perform ball milling, drying after the ball milling, and grinding to obtain a ball milled mixture; 5) The ball mill mixture and the binder are mixed and granulated, and then pressed into a shape to obtain a ceramic green body; 6) keeping the ceramic green body warm, and then sintering it a second time to obtain the ceramic capacitor material; In step 1), the mass ratio of barium titanate, yttrium oxide, cerium oxide, manganese oxide, calcium oxide, acidic silica sol and water is 100: (3-3.1): (2.3-2.5): (0.5-0.8): (2.0-2.2): (1.8-2.0): (100-110).

2. The preparation method according to claim 1, characterized in that The pH value of acidic silica sol is 2.5-2.8, and the silica mass content is 28-35%; The pH value of the alkaline silica sol is 9.0-9.5, and the mass content of silicon dioxide is 15-20%.

3. The preparation method according to claim 1 or 2, characterized in that The first sintering temperature is 1020-1050℃ and the sintering time is 3-5h; In step 6), the holding temperature is 550-580°C for 1-3 hours, and the second sintering temperature is 1200-1250°C for 2.5-3 hours.

4. The preparation method according to claim 1 or 2, characterized in that The average particle size of barium titanate is 200-250 nm.

5. The preparation method according to claim 1 or 2, characterized in that In step 1), the ball milling speed is 450-500 rpm, the ball milling time is 15-20 hours, the drying temperature is 100-105° C., and the drying time is 10-15 hours; In step 2), the ball milling speed is 450-500 rpm, the ball milling time is 15-20 hours, the drying temperature is 100-105° C., and the drying time is 10-15 hours; In step 4), the ball milling speed is 600-650 rpm, the ball milling time is 15-20 h, the drying temperature is 80-100° C., and the drying time is 5-10 h.

6. The preparation method according to claim 1 or 2, characterized in that Step 2) The amount of water added is 1-1.1 times the mass of barium titanate; The mass ratio of barium titanate to alkaline silica sol is 100:(0.8-1).

7. The preparation method according to claim 1 or 2, characterized in that The amount of anhydrous ethanol added is 0.8-1.0 times the mass of the primary sintered material; After grinding and pulverizing in step 4), the product is further screened through a 150-200 mesh sieve.

8. The preparation method according to claim 1 or 2, characterized in that The binder is selected from polyvinyl alcohol solution, the mass concentration of the polyvinyl alcohol solution is 10-14%, and the amount of polyvinyl alcohol solution added is 18-22% of the mass of the ball-milled mixture; The pressure in the compression molding step in step 5) is 200-240 MPa.

9. A combination wave ceramic capacitor material, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 8.

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