Preparation method of copper powder with low apparent density and copper powder

Abstract

The present invention discloses a method for preparing copper powder with low bulk density and the copper powder. The preparation method comprises mixing an additive, CuSO4·5H2O, H2SO4, and ultrapure water, and stirring thoroughly to obtain an electrolyte; placing the electrolyte in an electrolytic cell for electrolysis; wherein pure copper plates are used as anodes and cathodes, the distance between the cathode and cathode is controlled to be 20 cm, and the area ratio of the cathode to the anode is 1:1.25; the electrolyte temperature is 40-60°C, and the current density is 1000-1500A / m 2 , the electrolysis time is 8 to 20 minutes; after the electrolysis is completed, the product precipitated from the cathode is collected, rinsed with pure water 5 to 6 times, and then subjected to antioxidant treatment and vacuum drying to obtain copper powder with low apparent density. The reagents selected in this method are green, environmentally friendly, easily available, simple in preparation process, and easy to operate. The copper powder is dendritic, with a particle size of 5 to 20 μm and an apparent density of 0.4 to 0.7 g / cm 3 , with a purity of 99.95%, and a smaller bulk density, thus having a higher specific surface area and adsorption capacity.

Description

Technical Field

[0001] The present invention relates to the technical field of material preparation, and particularly relates to a preparation method and copper powder of copper powder with a low apparent density. Background Art

[0002] Copper powder is widely used in fields such as powder metallurgy, catalysis, and friction materials due to its excellent thermal conductivity, electrical conductivity, and good mechanical properties, pressing properties, and sintering properties. Among them, industries such as electrocarbon and electronic pastes require copper powder to have good electrical conductivity and wear resistance. Therefore, it is necessary to produce copper powder with a high specific surface area, a low apparent density, and well-developed dendritic morphology.

[0003] At present, the mainstream methods for preparing copper powder are the atomization method and the electrolytic deposition method. From the microscopic morphology, the copper powder produced by the atomization method has natural disadvantages in dendritic morphology, and its apparent density is usually 2.0 - 5.0 g / cm 3 . At the same time, the production of copper powder by the atomization method is affected by multiple processes such as copper melting, atomization, reduction, and ball milling, and it is difficult to stably control the morphology of the product, resulting in the copper powder produced by the atomization method being difficult to meet the requirements of industries such as electrocarbon and electronic pastes for copper powder. The electrolytic method for producing copper powder has a low apparent density and can produce special morphologies according to the optimization of process parameters, so it has been widely studied. However, at present, there are problems with the difficulty of stable production under the coupling of variable factors in the domestic production of low-apparent-density copper powder by the electrolytic method, and there is still a gap compared with the international advanced level.

[0004] Chinese Patent CN104475722A discloses a low-lead, low-apparent-density, highly dendritic electrolytic copper powder and its preparation method. By adding chloride ions with a concentration of 0.005 - 0.05 g / L to the electrolyte, highly dendritic low-lead electrolytic copper powder with an apparent density of 0.6 - 1.2 g / cm 3 was obtained. However, the apparent density of the electrolytic copper powder prepared by this method is still relatively high.

[0005] How to prepare copper powder with a low apparent density is still a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0006] Aiming at the above deficiencies existing in the prior art, the purpose of the present invention is to solve the problem of the high apparent density of copper powder prepared by the existing electrolytic method, and provide a preparation method and copper powder of copper powder with a low apparent density. The method has simple steps, and the prepared copper powder has small particle size and low apparent density.

[0007] To solve the above technical problems, the present invention adopts the following technical solutions:

[0008] A preparation method of copper powder with a low apparent density, comprising the following steps,

[0009] The additive, CuSO4·5H2O, H2SO4 and ultrapure water are mixed and stirred thoroughly to obtain an electrolyte;

[0010] The electrolyte is placed in an electrolytic cell for electrolysis; wherein, pure copper plates are used as anode and cathode, the distance between the cathode and the cathode is controlled to be 20 cm, and the area ratio of the cathode to the anode is 1:1.25; the electrolyte temperature is 40-60°C, and the current density is 1000-1500A / m 2 , electrolysis time is 8 to 20 minutes;

[0011] After the electrolysis is completed, the product precipitated at the cathode is collected, washed with pure water 5 to 6 times, and then subjected to antioxidant treatment and vacuum drying to obtain copper powder with low bulk density.

[0012] Preferably, in the electrolyte, Cu 2+ The concentration of is 6-20 g / L, the concentration of H2SO4 is 120-170 g / L, and the concentration of additives is 1.0-3.0 g / L.

[0013] Preferably, the additive is soluble starch.

[0014] Preferably, the ultrapure water is triple-distilled water, and the purity of the solid reagents used exceeds 99.9%.

[0015] Preferably, the additive is a polymer compound. To ensure sufficient dissolution in the electrolyte and continuous subsequent electrolysis, the sufficient stirring is to maintain the electrolyte at 40-70°C, preferably 50°C; the speed is 300-400r / min, preferably 350r / min; the time is 30-60min, preferably 60min.

[0016] Preferably, the electrolyte temperature is 50° C., and the electrolysis time is 15 min.

[0017] The present invention also discloses a copper powder prepared by the method for preparing copper powder with low apparent density; the copper powder is dendritic, has a particle size of 5 to 20 μm, and a bulk density of 0.4 to 0.7 g / cm 3 , with a purity of 99.95%.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] 1. The preparation method provided by the present invention adds soluble starch to the electrolyte, so that copper atoms are deposited and grown on certain crystal planes, thereby obtaining a dendritic copper powder, and the copper powder has a small particle size and a low bulk density. The additive used is a soluble hydrocarbon, which will not precipitate on the cathode, so it can remain in the electrolyte for a long time and can be recycled during the production process, thereby reducing production costs. At the same time, the addition of soluble hydrocarbons does not introduce other impurities, which can effectively avoid the defects of environmental pollution and harmful health of operators during the electrolytic production process. The purity of the electrolytic copper powder obtained by this method exceeds 99.95%. The reagents selected for this method are green, environmentally friendly, and easy to obtain. The preparation process is simple, easy to operate, and highly safe, and is suitable for industrial production.

[0020] 2. Compared with copper powder prepared by conventional electrolyte, the copper powder prepared by the method provided by the present invention has well-developed secondary dendrites, a well-developed dendritic appearance, and a particle size of 8 to 20 μm. Due to its well-developed dendritic dendrites, it has a more complex geometric structure and a larger surface roughness, a larger specific surface area, and more contact points, thus having higher electrical conductivity, thermal conductivity, compressibility and formability, as well as better machinability and chemical stability. The bulk density of the copper powder is 0.4 to 0.7 g / cm 3 , smaller bulk density can have a higher specific surface area and adsorption capacity, and reduce the amount of electrolytic copper powder used in actual production, thereby reducing the cost of use. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is the SEM image of the copper powder prepared in Example 1 of the present invention.

[0022] Figure 2 for Figure 1 A partial enlarged view of .

[0023] Figure 3 This is the SEM image of the copper powder prepared in Comparative Example 1.

[0024] Figure 4 for Figure 2 A partial enlarged view of . DETAILED DESCRIPTION

[0025] The embodiment of the present invention provides a method for preparing copper powder with low bulk density, comprising the following steps:

[0026] The additive, CuSO4·5H2O4, H2SO4 and ultrapure water are mixed and stirred thoroughly to obtain an electrolyte;

[0027] The electrolyte is placed in an electrolytic cell for electrolysis; among them, a pure copper plate is used as the anode and the cathode, the distance between the anode and the cathode is controlled to be 20 cm, and the area ratio of the cathode to the anode is 1:1.25; the electrolyte temperature is 40-60 °C, and the current density is 1000-1500 A / m 2 , and the electrolysis time is 8-20 min;

[0028] After the electrolysis is completed, the product deposited on the cathode is collected, rinsed 5-6 times with pure water, and then, after antioxidant treatment and vacuum drying, copper powder with a low apparent density is obtained.

[0029] Example 1

[0030] Copper sulfate pentahydrate, sulfuric acid and ultrapure water are mixed, and then, soluble starch is added to the obtained electrolyte so that the concentration of copper ions in the obtained electrolyte is 6.2 g / L, the concentration of sulfuric acid is 145 g / L, and the concentration of soluble starch is 1.0 g / L. The electrolyte is placed in a container at 50 °C, the rotation speed is maintained at 350 r / min, and mixed and dissolved for 60 min.

[0031] The electrolyte is placed in an electrolytic cell for electrolysis. A 99.99% pure copper plate is used as the cathode plate and the anode plate, the area ratio of the cathode to the anode is 1:1.25, the electrolyte temperature is maintained at 52.3 °C, the distance is 20 mm, and the current density is 1500 A / m 2， The two electrodes are energized for electrolysis for 15 min.

[0032] After the electrolysis is completed, the product deposited on the cathode is collected and washed 5-6 times with ultrapure water, and the washing time for each time is 30 min to 60 min. The powder after washing to remove sulfate ions is subjected to antioxidant treatment, filtration, and then dried in a vacuum drying oven at 70 °C for 12 h, and copper powder is obtained.

[0033] The SEM images of the copper powder prepared in this example are as shown in Figure 1 and 2 . Among them, Figure 4 is Figure 3 a partial enlarged view. From Figure 1 and Figure 2 , it can be seen that the copper powder prepared in this example is dendritic and the secondary dendrites are well developed. After testing, the particle size of the copper powder prepared in this example is 6.18-14.97 μm, the average particle size is 8.38 μm, and the apparent density of the copper powder measured by the funnel method (the same below) is 0.46 g / cm 3 . The purity of the copper powder measured by ICP (the same below) is 99.95%.

[0034] Example 2

[0035] Mix copper sulfate pentahydrate, sulfuric acid and ultrapure water, and then add soluble starch to the obtained electrolyte solution to make the concentration of copper ions in the obtained electrolyte solution 7.4 g / L, the concentration of sulfuric acid 156 g / L, and the concentration of soluble starch 3.0 g / L. Place the electrolyte solution in a container at 60 °C, keep the rotation speed at 350 r / min, and mix and dissolve for 60 min.

[0036] Place the electrolyte solution in an electrolytic cell for electrolysis. Use 99.99% pure copper plates as the cathode plate and the anode plate, the area ratio of the cathode to the anode is 1:1.25, keep the temperature of the electrolyte solution at 54.5 °C, the distance is 20 mm, and use a current density of 1200 A / m 2， Apply current to both electrodes for electrolysis for 15 min.

[0037] After the electrolysis is completed, collect the product deposited on the cathode and wash it with ultrapure water 5 - 6 times, with each washing time being 30 min to 60 min. Conduct antioxidant treatment and filtration on the powder after washing to remove sulfate ions, and then dry it in a vacuum drying oven at 70 °C for 12 h to obtain copper powder. The obtained copper powder is sealed and stored with inert gas.

[0038] The morphology of the copper powder prepared in this example is similar to that in Example 1. After testing, the particle size of the copper powder prepared in this example is 9.51 - 20.37 μm, and the average particle size is 14.64 μm. After testing, the loose bulk density of the tested copper powder is 0.68 g / cm 3 and the purity of the copper powder is 99.95%.

[0039] Example 3

[0040] Mix copper sulfate pentahydrate, sulfuric acid and ultrapure water, and then add soluble starch to the obtained electrolyte solution to make the concentration of copper ions in the obtained electrolyte solution 7.5 g / L, the concentration of sulfuric acid 158 g / L, and the concentration of soluble starch 2.0 g / L. Place the electrolyte solution in a container at 50 °C, keep the rotation speed at 350 r / min, and mix and dissolve for 60 min.

[0041] Place the electrolyte solution in an electrolytic cell for electrolysis. Use 99.99% pure copper plates as the cathode plate and the anode plate, the area ratio of the cathode to the anode is 1:1.25, keep the temperature of the electrolyte solution at 55.4 °C, the distance is 20 mm, and use a current density of 1450 A / m 2， Apply current to both electrodes for electrolysis for 15 min.

[0042] After the electrolysis is completed, collect the product deposited on the cathode and wash it with ultrapure water 5 - 6 times, with each washing time being 30 min to 60 min. Conduct antioxidant treatment and filtration on the powder after washing to remove sulfate ions, and then dry it in a vacuum drying oven at 80 °C for 12 h to obtain copper powder. The obtained copper powder is sealed and stored with inert gas.

[0043] The morphology of the copper powder prepared in this example is similar to that in Example 1. After testing, the particle size of the copper powder prepared in this example is 8.56 - 16.16 μm, and the average particle size is 11.81 μm. After testing, the loose bulk density of the tested copper powder is 0.59 g / cm 3 , and the purity of the copper powder is 99.95%.

[0044] Example 4

[0045] Mix copper sulfate pentahydrate, sulfuric acid and ultrapure water, and then add soluble starch to the obtained electrolyte to make the concentration of copper ions in the obtained electrolyte 8.2 g / L, the concentration of sulfuric acid 148 g / L, and the concentration of soluble starch 2 g / L. Place the electrolyte in a container at 50 °C, keep the rotation speed at 350 r / min, and mix and dissolve for 60 min.

[0046] Place the electrolyte in an electrolytic cell for electrolysis. Use 99.99% pure copper plates as the cathode plate and the anode plate, the area ratio of the cathode to the anode is 1:1.25, keep the electrolyte temperature at 52.1 °C, the distance is 20 mm, and apply an electric current density of 1300 A / m 2， Apply an electric current to both electrodes for electrolysis for 15 min.

[0047] After the electrolysis is completed, collect the product deposited on the cathode and wash it 5 - 6 times with ultrapure water, with each washing time being 30 min - 60 min. Perform antioxidant treatment and filtration on the powder after washing to remove sulfate ions, and then dry it in a vacuum drying oven at 80 °C for 12 h to obtain copper powder. The obtained copper powder is sealed and stored with inert gas.

[0048] The morphology of the copper powder prepared in this example is similar to that in Example 1. After testing, the particle size of the copper powder prepared in this example is 7.48 - 19.41 μm, and the average particle size is 13.25 μm. After testing, the loose bulk density of the tested copper powder is 0.65 g / cm 3 , and the purity of the copper powder is 99.95%.

[0049] Example 5

[0050] Mix copper sulfate pentahydrate, sulfuric acid and ultrapure water, and then add soluble starch to the obtained electrolyte to make the concentration of copper ions in the obtained electrolyte 6.6 g / L, the concentration of sulfuric acid 163 g / L, and the concentration of soluble starch 1 g / L. Place the electrolyte in a container at 50 °C, keep the rotation speed at 350 r / min, and mix and dissolve for 60 min.

[0051] Place the electrolyte in an electrolytic cell for electrolysis. Use 99.99% pure copper plates as the cathode plate and the anode plate, the area ratio of the cathode to the anode is 1:1.25, keep the electrolyte temperature at 49.8 °C, the distance is 20 mm, and apply an electric current density of 1300 A / m2， Electrolyze for 15 min with electricity applied to both electrodes.

[0052] After the electrolysis is completed, collect the product deposited on the cathode and wash it with ultrapure water 5 - 6 times. The washing time for each time is 30 min to 60 min. Perform antioxidant treatment and filtration on the powder after washing to remove sulfate ions, and then dry it in a vacuum drying oven at 80 °C for 12 h to obtain copper powder. The obtained copper powder is stored sealed with inert gas.

[0053] The morphology of the copper powder prepared in this example is similar to that in Example 1. After testing, the particle size of the copper powder prepared in this example is 7.48 - 15.35 μm, and the average particle diameter is 11.39 μm. After testing, the apparent density of the tested copper powder is 0.53 g / cm 3 , and the purity of the copper powder is 99.95%.

[0054] Example 6

[0055] Mix copper sulfate pentahydrate, sulfuric acid and ultrapure water, and then add soluble starch to the obtained electrolyte solution to make the concentration of copper ions in the obtained electrolyte solution 7.8 g / L, the concentration of sulfuric acid 157 g / L, and the concentration of soluble starch 3 g / L. Place the electrolyte solution in a container at 50 °C, keep the rotation speed at 350 r / min, and mix and dissolve for 60 min.

[0056] Place the electrolyte solution in an electrolytic cell for electrolysis. Use 99.99% pure copper plates as the cathode plate and the anode plate. The area ratio of the cathode to the anode is 1:1.25. Keep the electrolyte solution temperature at 50.4 °C, the distance is 20 mm, and the current density is 1400 A / m 2， Electrolyze for 15 min with electricity applied to both electrodes.

[0057] After the electrolysis is completed, collect the product deposited on the cathode and wash it with ultrapure water 5 - 6 times. The washing time for each time is 30 min to 60 min. Perform antioxidant treatment and filtration on the powder after washing to remove sulfate ions, and then dry it in a vacuum drying oven at 80 °C for 12 h to obtain copper powder. The obtained copper powder is stored sealed with inert gas.

[0058] The morphology of the copper powder prepared in this example is similar to that in Example 1. After testing, the particle size of the copper powder prepared in this example is 8.64 - 19.16 μm, and the average particle diameter is 12.72 μm. After testing, the apparent density of the tested copper powder is 0.63 g / cm 3 , and the purity of the copper powder is 99.95%.

[0059] Comparative Example 1

[0060] ((End)) Mix copper sulfate pentahydrate, sulfuric acid and ultrapure water to obtain an electrolyte solution, and the concentration of copper ions in the obtained electrolyte solution is 7.4 g / L, and the concentration of sulfuric acid is 156 g / L.

[0061] (2) Place the electrolyte in an electrolytic cell for electrolysis. Use copper plates as the cathode and anode plates, with the area ratio of the cathode to the anode being 1:1.25. Keep the electrolyte temperature at 50 °C, the spacing at 20 mm, and apply an electric current density of 1200 A / m 2 , and energize the two electrodes for electrolysis for 15 minutes. Collect the copper powder deposited on the cathode and wash it 5 - 6 times with ultrapure water, with each washing time being 30 - 60 minutes. Subject the powder after washing to remove sulfate ions to antioxidant treatment, filtration, and then dry it in a vacuum drying oven at 80 °C for 12 hours to obtain copper powder.

[0062] The morphology of the copper powder is as Figure 3 and Figure 4 shown, where Figure 4 is Figure 3 a partial enlarged view. It can be seen from the figure that the prepared copper powder has certain dendrites, but the dendrites are thick and short and not well-developed. The particle size of the tested copper powder is 11.96 - 26.91 μm, and the average particle size is 15.81 μm. The apparent density of the tested copper powder is 0.76 g / cm 3 , and the purity is 99.95%

[0063] The comparison of relevant parameters in Examples 1 - 6 and Comparative Example 1 is shown in Table 1.

[0064] Table 1

[0065]

[0066] It can be seen from Table 1 that the addition of additives will improve the electrolytic deposition products. Specifically, the apparent density of the copper powder decreases (compared with the copper powder prepared without adding soluble starch), and the secondary dendrites of the copper powder are well-developed. However, when the copper ion concentration and additive concentration are high, it is not conducive to the preparation of copper powder with a low apparent density, while the increase in the current density will refine the particle size of the copper powder, which is conducive to the preparation of copper powder with a low apparent density.

[0067] Compared with the copper powder prepared from the conventional electrolyte, the copper powder prepared by the method provided by the present invention has well-developed secondary dendrites, and the appearance is in the shape of well-developed dendrites, with a particle size of 8 - 20 μm. Due to its well-developed dendritic branches, it has a more complex geometric structure, a larger surface roughness, a larger specific surface area, and more contact points, and thus has higher electrical conductivity, thermal conductivity, compressibility, and formability, as well as better processability and chemical stability. The apparent density of the copper powder is 0.4 - 0.7 g / cm 3 , and a smaller apparent density can have a higher specific surface area and adsorption capacity, and reduce the usage amount of electrolytic copper powder in actual production, thereby reducing the usage cost.

[0068] Obviously, those skilled in the art can make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these modifications and variations.

Claims

1. A method for preparing copper powder with a low tap density, characterized in that, including the following steps, The additive, CuSO4·5H2O, H2SO4 and ultrapure water are mixed and stirred thoroughly to obtain an electrolyte, wherein: Cu 2+ The concentration of is 6-20 g / L, the concentration of H2SO4 is 120-170 g / L, the concentration of the additive is 1.0-3.0 g / L, and the additive is soluble starch; The electrolyte is placed in an electrolytic cell for electrolysis; among them, a pure copper plate is used as the anode and the cathode, the distance between the anode and the cathode is controlled to be 20 cm, and the area ratio of the cathode to the anode is 1:1.25; the temperature of the electrolyte is 40-50 °C, and the current density is 1000-1500 A / m 2 , and the electrolysis time is 8-20 min; After electrolysis, the product deposited on the cathode is collected, rinsed 5 to 6 times with pure water, and then obtained dendritic copper powder with low apparent density after antioxidant treatment and vacuum drying.

2. The preparation method of copper powder with low apparent density according to claim 1, wherein The ultrapure water is triple-distilled water, and the purity of all solid reagents used exceeds 99.9%.

3. The preparation method of copper powder with low tap density according to claim 1, characterized in that, The sufficient stirring is to stir the electrolyte at 40-70°C and a rotation speed of 300-400 r / min for 30-60 min.

4. The preparation method of copper powder with low tap density according to claim 1, characterized in that, The temperature of the electrolyte is 50°C, and the electrolysis time is 15 min.

5. A copper powder, characterized in that, Prepared by using the preparation method of copper powder with low apparent density as described in claim 1; the copper powder is dendritic, with a particle size of 5-20 μm and an apparent density of 0.4-0.7 g / cm 3 , and the purity is 99.95%.

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