Method for reducing carbon impurity content of high-pressure tantalum powder

Abstract

The invention discloses a method for reducing the content of carbon impurities in high-pressure tantalum powder. The method comprises the following steps that the high-pressure tantalum powder is added into a mixed alcohol solution to be stirred; then filtering and cleaning the mixed alcohol solution mixed with the high-pressure tantalum powder by using a filtering piece to obtain primarily treated high-pressure tantalum powder; adding a solid substance obtained by filtering into an acid solution and stirring; filtering the acidic solution of the mixed solid substances by using a filtering piece; and carrying out vacuum drying on a solid substance obtained by filtering to finish the treatment. According to the method, the dissolving effect of the carbon compound under the high-temperature condition is remarkably improved, and deep carbon impurities of the high-pressure tantalum powder are effectively removed. The acetic acid aqueous solution is adopted as an additional treatment step, it is ensured that stubborn carbon impurities can also be effectively removed, and therefore the purity and performance of the high-pressure tantalum powder are greatly improved. After the high-pressure tantalum powder is treated by the whole treatment process, not only is the residue of carbon impurities reduced, but also the quality stability of a final product is greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of tantalum powder preparation technology, and particularly relates to a method for reducing the carbon impurity content of high-pressure tantalum powder. Background Technology

[0002] Carbon is a crucial factor affecting the withstand voltage of high-voltage tantalum powder; the higher the carbon content, the weaker the withstand voltage. Currently, a small amount of carbon is typically introduced into the production process of high-voltage tantalum powder. This carbon content reduces the withstand voltage of the high-voltage tantalum powder, usually resulting in high leakage current and low breakdown voltage in high-voltage tantalum capacitors, thus reducing the yield and reliability of high-voltage tantalum capacitors.

[0003] Although existing technologies have proposed methods for removing impurities from tantalum powder, these methods do not analyze and remove carbon content.

[0004] The patent document with publication number CN106270482A discloses a method for improving the performance of tantalum powder, as well as the tantalum powder and the tantalum capacitor anode block prepared from the tantalum powder. It uses substances including polyethylene glycol, acetone, and ethanol to treat the tantalum powder. However, this technology is used to improve the forming efficiency of tantalum blocks and reduce the friction damage rate between the tantalum blocks and the mold, but does not involve the removal of carbon elements.

[0005] Patent document with publication number CN115570127A discloses a method for preparing tantalum powder. Although the method mentions the purification of tantalum powder, it does not consider the removal of carbon elements.

[0006] Therefore, the existing technical solutions described above still need to be improved in terms of removing carbon impurities from the surface of high-pressure tantalum powder. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a method for reducing the carbon impurity content of high-voltage tantalum powder.

[0008] The present invention is achieved through the following technical solutions.

[0009] This invention provides a method for reducing the carbon impurity content of high-voltage tantalum powder, comprising the following steps: S1: Add high-pressure tantalum powder to the mixed alcohol solution and stir; S2: Then, the mixed alcohol solution of the mixed high-pressure tantalum powder is filtered and washed using a filter to obtain pre-treated high-pressure tantalum powder; S3: Add the solid substance obtained by filtration in step S2 into the acidic solution and stir; S4: Then use a filter to filter the acidic solution of the mixed solids; S5: Vacuum dry the solid material obtained from filtering in step S4 to complete the step of reducing the carbon impurity content of high-pressure tantalum powder.

[0010] Preferably, the mixed alcohol solution comprises anhydrous ethanol, polyethylene glycol, acetone, and water.

[0011] Preferably, in the mixed alcohol solution, anhydrous ethanol accounts for 20% to 95% of the total volume, polyethylene glycol accounts for 1% to 10% of the total volume, and acetone accounts for 1% to 20% of the total volume.

[0012] Preferably, the acidic solution is an aqueous solution of acetic acid.

[0013] Preferably, the acidic solution is a 1% to 10% aqueous solution of acetic acid.

[0014] Preferably, in step S1, the high-pressure tantalum powder is added to a mixed alcohol solution at 30°C to 60°C and stirred for 2 to 4 hours.

[0015] Preferably, in step S3, the solid material obtained by filtration in step S2 is added to an acidic solution at 50°C to 80°C and stirred for 2 to 4 hours.

[0016] Preferably, the pore size of the filter element in steps S2 and S4 is 0.2 micrometers to 10 micrometers.

[0017] Preferably, the filter element is made of ceramic or metal.

[0018] Preferably, the vacuum drying conditions are: drying at a temperature of 60℃~120℃ and a vacuum degree of 0.1Pa~10Pa for 4h~12h.

[0019] The beneficial effects of this invention are as follows: 1. The method of the present invention significantly improves the dissolution effect of carbon compounds under high temperature conditions, and achieves effective removal of deep carbon impurities in high-pressure tantalum powder.

[0020] 2. By precisely controlling the processing temperature and time, the adaptability to the characteristics of high-pressure tantalum powder and the processing efficiency during the cleaning process are improved.

[0021] 3. An additional treatment step using acetic acid aqueous solution ensures that stubborn carbon impurities can be effectively removed, thereby greatly improving the purity and performance of high-pressure tantalum powder.

[0022] 4. After the high-pressure tantalum powder undergoes the entire processing procedure, not only is the residual carbon impurities reduced, but the quality stability of the final product is also greatly improved. Detailed Implementation

[0023] The technical solution of the present invention is further described below, but the scope of protection is not limited to what is described.

[0024] Example 1: A method for reducing the carbon impurity content of high-voltage tantalum powder, comprising the following steps: S1: Add high-pressure tantalum powder to a mixed alcohol solution at 30°C and stir for 2 hours to dissolve the carbon compounds adsorbed on the surface of the tantalum powder. S2: Then, the mixed alcohol solution of the mixed high-pressure tantalum powder is filtered using a filter and preliminarily rinsed with pure water to obtain pre-treated high-pressure tantalum powder; S3: Add the solid material obtained by filtration in step S2 to a 1% acetic acid aqueous solution at 50°C and stir for 2 hours; S4: Then use a filter to filter the acidic solution of the mixed solids; S5: Vacuum dry the solid material obtained from filtering in step S4 to complete the step of reducing the carbon impurity content of high-pressure tantalum powder.

[0025] The solutes in the mixed alcohol solution are anhydrous ethanol, polyethylene glycol, and acetone, and the solvent is deionized water.

[0026] In the mixed alcohol solution, anhydrous ethanol accounts for 20% of the total volume, polyethylene glycol accounts for 10% of the total volume, acetone accounts for 20% of the total volume, and the remainder is deionized water.

[0027] The pore size of the filter element in steps S2 and S4 is 0.2 micrometers.

[0028] The filter element is made of ceramic material.

[0029] The vacuum drying conditions are as follows: high-pressure tantalum powder is placed in a high-pressure resistant container, then the container is sealed and moved into an oven, and the vacuum pump is turned on. The powder is dried for 4 hours at a temperature of 120°C and a vacuum degree of 0.1 Pa.

[0030] Example 2: A method for reducing the carbon impurity content of high-voltage tantalum powder, comprising the following steps: S1: Add high-pressure tantalum powder to a mixed alcohol solution at 60°C and stir for 4 hours to dissolve the carbon compounds adsorbed on the surface of the tantalum powder. S2: Then, the mixed alcohol solution of the mixed high-pressure tantalum powder is filtered using a filter and preliminarily rinsed with pure water to obtain pre-treated high-pressure tantalum powder; S3: Add the solid material obtained by filtration in step S2 to a 10% acetic acid aqueous solution at 80°C and stir for 4 hours; S4: Then use a filter to filter the acidic solution of the mixed solids; S5: Vacuum dry the solid material obtained from filtering in step S4 to complete the step of reducing the carbon impurity content of high-pressure tantalum powder.

[0031] The solutes in the mixed alcohol solution are polyethylene glycol and acetone, and the solvents are water and anhydrous ethanol.

[0032] In the mixed alcohol solution, anhydrous ethanol accounts for 95% of the total volume, polyethylene glycol accounts for 1% of the total volume, and acetone accounts for 1% of the total volume.

[0033] The pore size of the filter element in steps S2 and S4 is 10 micrometers.

[0034] The filter element is made of corrosion-resistant metal.

[0035] The vacuum drying conditions are as follows: high-pressure tantalum powder is placed in a high-pressure resistant container, then the container is sealed and moved into an oven, and the vacuum pump is turned on. The powder is dried for 12 hours at a temperature of 60°C and a vacuum of 0Pa.

[0036] Example 3: A method for reducing the carbon impurity content of high-voltage tantalum powder, comprising the following steps: S1: Add high-pressure tantalum powder to a mixed alcohol solution at 50°C and stir for 3 hours to dissolve the carbon compounds adsorbed on the surface of the tantalum powder. S2: Then, the mixed alcohol solution of the mixed high-pressure tantalum powder is filtered using a filter and preliminarily rinsed with pure water to obtain pre-treated high-pressure tantalum powder; S3: Add the solid material obtained by filtration in step S2 to a 5% acetic acid aqueous solution at 60℃ and stir for 3 hours. S4: Then use a filter to filter the acidic solution of the mixed solids; S5: Vacuum dry the solid material obtained from filtering in step S4 to complete the step of reducing the carbon impurity content of high-pressure tantalum powder.

[0037] The solutes in the mixed alcohol solution are anhydrous ethanol, polyethylene glycol, and acetone, and the solvent is deionized water.

[0038] In the mixed alcohol solution, anhydrous ethanol accounts for 60% of the total volume, polyethylene glycol accounts for 5% of the total volume, acetone accounts for 12% of the total volume, and the remainder is deionized water.

[0039] The pore size of the filter element in steps S2 and S4 is 6 micrometers.

[0040] The filter element is made of ceramic material.

[0041] The vacuum drying conditions are as follows: high-pressure tantalum powder is placed in a high-pressure resistant container, then the container is sealed and moved into an oven, and the vacuum pump is turned on. The powder is dried for 7 hours at a temperature of 90°C and a vacuum degree of 5Pa.

[0042] 1000g of FTM200 high-pressure tantalum powder with a carbon content of 20ppm was treated using the methods in Examples 1-3. The treatment results are shown in the table below.

[0043] As can be seen from the table above, the method of the present invention can effectively remove carbon from high-pressure tantalum powder and maintain the good performance of high-pressure tantalum powder.

[0044] CAK55 capacitors were produced using high-voltage tantalum powder processed in Examples 1-3. The performance of the capacitor anodes is shown in the table below.

[0045] In this invention, the selection and proportioning of anhydrous ethanol, polyethylene glycol, and acetone in the mixed alcohol solution are designed to enhance the solubility of carbon compounds under high-temperature conditions, especially for deep-seated carbon impurities that are difficult to remove, ensuring that these impurities are fully dissolved and effectively removed in subsequent processing. Next, the mixed alcohol solution is heated to a specified temperature, and the high-pressure tantalum powder to be treated is placed in the solution and held for a controlled period. This process helps improve the adaptability to high-pressure tantalum powders with different properties by adjusting the chemical activity of the solution and environmental conditions, such as temperature and soaking time, while simultaneously enhancing washing efficiency and ensuring the safety and reliability of the process.

[0046] After the soaking process, the high-pressure tantalum powder is removed and initially rinsed with pure water to remove any residual mixed alcohol solution from the surface. Then, to further remove any trace carbon impurities, an acetic acid aqueous solution is used as a second-stage treatment to further process the high-pressure tantalum powder. The introduction of the acetic acid aqueous solution not only addresses the stubborn carbon impurities not completely removed in the first stage but also ensures that the high-pressure tantalum powder reaches a higher purity standard, which is crucial for improving its final performance. The high-pressure tantalum powder treated in this way exhibits significantly improved purity and related physicochemical properties, with effective control over residual carbon impurities during production, and substantial improvements in stability and consistency, providing a high-quality raw material guarantee for subsequent electronic component manufacturing.

[0047] The microporous filtration process employed in this invention utilizes ceramic materials with excellent heat resistance or corrosion-resistant porous metal materials. The micropore diameter of these materials is set between 0.2 micrometers and 10 micrometers. This design effectively intercepts large particles during the pretreatment stage while allowing fine carbon compounds and other soluble impurities to pass through, ensuring the purity of subsequent processing. The selection of microporous materials and precise control of pore size are crucial for reducing mechanical wear under high-pressure processing environments and maintaining stable equipment operation.

[0048] To further improve the dissolution efficiency of carbon compounds and the removal efficiency of carbon impurities, precise control of temperature and time was implemented in the subsequent processing steps. Experiments revealed that the separation effect between carbon impurities and high-pressure tantalum powder was optimal within a specific temperature range. Combined with prolonged continuous heating, this allowed for a more thorough dissolution of carbon compounds, achieving deep cleaning. In this process, precise adjustment of temperature and time is crucial for improving cleaning efficiency and maintaining the properties of the high-pressure tantalum powder.

[0049] This invention employs an acetic acid aqueous solution with a concentration ranging from 1% to 10% (by weight), and the temperature during the treatment process is strictly controlled within the range of 50°C to 80°C. This method aims to enhance the solubility of carbon compounds, especially stubborn impurities, through physical and chemical reactions under specific conditions, thereby achieving deep and comprehensive cleaning of high-pressure tantalum powder. Specifically, under this temperature and concentration environment, the acetic acid aqueous solution significantly promotes the decomposition and dissolution of carbon compound molecules, making these impurities easily detach from the surface of the high-pressure tantalum powder and dissolve into the solution. This not only improves the cleaning effect, ensuring that even fine or deeply embedded impurities are left without residue, but also better adapts to and protects the physical and chemical properties of the high-pressure tantalum powder throughout the cleaning process, avoiding product damage or property changes due to improper handling. Furthermore, by precisely controlling the treatment time and temperature parameters, the efficiency and specificity of each step are ensured, making the entire process smoother and more efficient.

[0050] In this invention, high-pressure tantalum powder is placed in a high-pressure resistant container for vacuum drying, thereby ensuring the full evaporation of moisture and solvents inside the material and reducing carbon impurities. The oven temperature is carefully selected to effectively promote the decomposition and volatilization of carbon compounds; too low a temperature will not achieve the desired drying effect, while too high a temperature may alter the material properties. Vacuum control is primarily to lower the evaporation point of the substance, allowing it to escape at a lower temperature, while also preventing secondary contamination of the high-pressure tantalum powder by external air.

[0051] The application of this method not only significantly improves the purity and performance of high-pressure tantalum powder, resulting in higher stability and reliability of the final product in practical applications, but also simplifies the production process, reduces processing costs, and ensures consistent product quality. High-pressure tantalum powder processed in this way exhibits greatly improved purity, laying a more solid foundation for subsequent processing and use.

Claims

1. A method of reducing the carbon impurity content of high pressure tantalum powder, characterized by, The method comprises the following steps: S1: adding high-pressure tantalum powder into a mixed alcohol solution and stirring; S2: filtering and cleaning the mixed alcohol solution of the high-pressure tantalum powder by using a filter to obtain initially treated high-pressure tantalum powder; S3: adding the solid substance obtained by filtering in step S2 into an acid solution and stirring; S4: filtering the acid solution of the solid substance by using a filter; S5: vacuum drying the solid substance obtained by filtering in step S4 to complete the step of reducing the carbon impurity content of the high-pressure tantalum powder.

2. The method of reducing carbon impurities in high pressure tantalum powder of claim 1, wherein: The mixed alcohol solution comprises anhydrous ethanol, polyethylene glycol, acetone and water.

3. The method of reducing carbon impurities in high pressure tantalum powder of claim 2, wherein: In the mixed alcohol solution, the anhydrous ethanol accounts for 20%-95% of the total volume, the polyethylene glycol accounts for 1%-10% of the total volume, and the acetone accounts for 1%-20% of the total volume.

4. The method of reducing carbon impurities in high pressure tantalum powder of claim 1, wherein: The acid solution is an aqueous acetic acid solution.

5. The method of reducing carbon impurities in high pressure tantalum powder of claim 4, wherein: The acid solution is an aqueous acetic acid solution with a concentration of 1%-10%.

6. The method of reducing carbon impurities in high pressure tantalum powder of claim 1, wherein: In step S1, the high-pressure tantalum powder is added into the mixed alcohol solution at 30-60°C and stirred for 2-4 hours.

7. The method of reducing carbon impurities in high pressure tantalum powder of claim 1, wherein: In step S3, the solid substance obtained by filtering in step S2 is added into the acid solution at 50-80°C and stirred for 2-4 hours.

8. The method of reducing carbon impurities in high pressure tantalum powder of claim 1, wherein: The filter hole diameter of the filter used in steps S2 and S4 is 0.2-10 microns.

9. The method of reducing carbon impurities in high pressure tantalum powder of claim 8, wherein: The filter is made of ceramic material or metal.

10. The method of reducing carbon impurities in high pressure tantalum powder of claim 1, wherein: The vacuum drying condition is that the temperature is 60-120°C, the vacuum degree is 0.1-10 Pa, and the drying time is 4-12 hours.

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