Preparation method of coral-like copper powder and copper powder

Abstract

The application discloses a preparation method of coral-like copper powder, which comprises the following steps: mixing an additive S, CuSO4*5H2O, H2SO4 and pure water to form a solution; placing the solution in a 40-60 DEG C stirrer, keeping the rotating speed at 300-480 r / min, and dissolving for 30-60 min to obtain an electrolyte; placing the electrolyte in an electrolytic cell to perform electrolysis; collecting the product separated from the cathode after the electrolysis, washing the product with pure water for 3-5 times, and performing saponification and antioxidation treatment, and then vacuum drying the product at 60 DEG C for 12 h to obtain the coral-like copper powder. The method is simple and easy to operate. The application further discloses the copper powder prepared by the method, and the copper powder has small particle size, low loose bulk density and large surface roughness.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of material preparation, in particular to a preparation method of coral-like copper powder and the copper powder. BACKGROUND

[0002] The copper powder is widely used in powder metallurgy, catalysis, friction material and other fields due to its excellent thermal conductivity, electrical conductivity, and good mechanical properties, pressing performance and sintering performance. Among them, the industries of electric carbon and electronic paste require the copper powder to have good electrical conductivity and wear resistance, so it is necessary to produce the copper powder with high specific surface area, low apparent density and developed dendritic shape.

[0003] At present, the mainstream methods for preparing the copper powder are atomization method and electrolysis deposition method. From the micro-morphology, the copper powder produced by the atomization method has natural disadvantages in dendritic morphology, and the apparent density thereof is usually 2.0-5.0 g / cm 3 . Meanwhile, the production of the copper powder by the atomization method is affected by multiple processes such as copper smelting, atomization, reduction and ball milling, so it is difficult to stably control the morphology of the product, which leads to the fact that the copper powder produced by the atomization method is difficult to meet the demand of the industries of electric carbon and electronic paste for the copper powder. The electrolysis method can produce the copper powder with low apparent density and special morphology according to the optimization of process parameters, so it has been widely studied. However, at present, the domestic production of the copper powder with low apparent density by the electrolysis method has the problem of difficulty in stable production under the coupling of multiple variable factors, and there is still a gap with the international advanced level.

[0004] Chinese patent CN104475722A discloses a low-lead low-apparent-density high-dendritic electrolytic copper powder and a preparation method thereof, and the high-dendritic low-lead electrolytic copper powder with the apparent density of 0.6-1.2 g / cm 3 is prepared by adding the chloride ions with the concentration of 0.005-0.05 g / L in the electrolyte. However, the apparent density of the electrolytic copper powder prepared by the method is still relatively high.

[0005] How to prepare the copper powder with low apparent density is still a technical problem to be solved by the person skilled in the art. SUMMARY

[0006] In view of the above problems in the prior art, the purpose of the present application is to solve the problem of high apparent density of the copper powder prepared by the existing electrolysis method, and to provide a preparation method of coral-like copper powder and the copper powder. The method has simple steps, and the prepared copper powder has small particle size and low apparent density.

[0007] In order to solve the above technical problems, the technical scheme adopted by the present application is as follows:

[0008] A preparation method of coral-like copper powder comprises the following steps,

[0009] The additive S, CuSO4·5H2O, H2SO4 and pure water are mixed to form a solution; the solution is placed in a 40-60℃ stirrer, the rotating speed is kept at 300-480r / min, and the solution is dissolved for 30-60min to obtain an electrolyte;

[0010] The electrolyte is placed in an electrolytic cell for electrolysis; pure copper plate is used as anode and cathode, the distance between anode and cathode is controlled at 3-5cm, the working electrode area is 0.01-1m 2 ; the electrolyte temperature is 40-60℃, the current density is 1200-1600A / m 2 , and the electrolysis time is 5-8min;

[0011] After the electrolysis, the product on the cathode is collected, washed with pure water for 3-5 times, and then subjected to saponification and antioxidation treatment, and then vacuum dried at 60℃ for 12h to obtain the coral-like copper powder.

[0012] As a preferred embodiment, in the solution, the concentration of copper ions is 0.10-0.15mol / L, the concentration of sulfuric acid is 1.2-1.6mol / L, and the concentration of the additive S is 0.0003-0.001mol / L; within this range, the current efficiency is the highest, and the coral-like dendrites of the copper powder obtained are more developed, the copper powder is more fluffy, and the bulk density is lower.

[0013] Further, the silicotungstate is a soluble silicotungstate. The silicotungstate is preferably copper silicotungstate.

[0014] As a preferred embodiment, the electrolyte temperature is preferably 55℃; at this temperature, the copper powder obtained has higher current efficiency and lower energy consumption. When the temperature is lower than 55℃, the current efficiency will decrease and the energy consumption will be higher. When the temperature is higher than 55℃, the current efficiency will not be significantly improved, but the evaporation amount of the electrolyte, acid mist, energy consumption and bulk density of the copper powder will all increase.

[0015] In a specific embodiment, the saponification and antioxidation treatment is as follows: the product on the cathode plate is scraped into pure water and washed for 5 times, then immersed in a saponification solution (50% sodium fatty acid, 10% sodium dodecylbenzenesulfonate, 2% sodium tripolyphosphate, 5% ethanol, 5% ethylene glycol and 2% sodium carbonate) for 5min; then washed with pure water for 3 times, immersed in 20% benzotriazole for 10min; then washed with pure water for 2 times, immersed in 5% disodium EDTA dihydrate for 15min, washed with pure water for 3 times, and then dehydrated, transferred to a vacuum drying oven at 343K and dried for 8-12h to obtain the copper powder.

[0016] The present invention also provides a copper powder, prepared by the aforementioned method for preparing coral-like copper powder; the copper powder has a coral-like morphology and a loose bulk density of 0.30–0.50 g / cm³. 3 The particle size is 4–10 μm, and the purity is 99.9%.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] 1. The preparation method provided by this invention involves adding silicotungstic acid or silicotungstate as an additive to the electrolyte. Due to the presence of silicotungstate ions, copper ions preferentially grow on the (331) crystal plane when they are converted into copper grains, thereby stably preparing coral-like copper powder under optimized electrolyte formulation and electrolysis process conditions. The additive is a soluble substance and will not precipitate on the cathode, thus it can remain in the electrolyte for a long time and can be recycled during production, thereby reducing production costs. The purity of the electrolytic copper powder prepared by this method exceeds 99.9%. This preparation method is simple, easy to operate, and highly safe, making it suitable for industrial production.

[0019] 2. The copper powder prepared by the method provided in this invention has a fluffy coral-like appearance with a particle size of 4–10 μm. It further expands from the long, slender columnar dendrites radially produced from the main axis, with each branch exhibiting uniform length and size distribution. Due to its fluffy coral-like shape, it possesses a more complex geometric structure, greater surface roughness, larger specific surface area, and more contact points, resulting in higher electrical conductivity, thermal conductivity, hydrophobicity, compressibility, formability, and better processability. Compared to the corn-like copper powder morphology obtained without additive S, the fluffy coral-like morphology forms more interlocking dendrites, possessing a more complex geometric structure, thus exhibiting a larger specific surface area and more contact sites. The loose bulk density of this copper powder is 0.30–0.50 g / cm³. 3 A smaller bulk density results in a higher specific surface area and adsorption capacity, making it easier to form a porous structure and reducing the amount of electrolytic copper powder used in actual production, thereby reducing usage costs. Attached Figure Description

[0020] Figure 1 This is a SEM image of the copper powder prepared in Example 1 of the present invention.

[0021] Figure 2 This is a SEM image of the copper powder prepared in Example 2 of the present invention.

[0022] Figure 3 This is a SEM image of the copper powder prepared in Example 3 of the present invention.

[0023] Figure 4 This is a SEM image of the copper powder prepared in Example 4 of the present invention.

[0024] Figure 5 SEM image of copper powder prepared for Comparative Example 1. DETAILED DESCRIPTION

[0025] The present application provides a preparation method of coral-like copper powder, comprising the following steps,

[0026] The additive S, CuSO4·5H2O, H2SO4 and pure water are mixed to form a solution; the solution is placed in a 40-60℃ stirrer, the rotating speed is kept at 300-480r / min, and the solution is dissolved for 30-60min to obtain an electrolyte;

[0027] The electrolyte is placed in an electrolytic cell for electrolysis; wherein pure copper plate is used as anode and cathode, the distance between the anode and cathode is controlled at 3-5cm, the working electrode area is 0.01-1m 2 , the electrolyte temperature is 40-60℃, the current density is 1200-1600A / m 2 , and the electrolysis time is 5-8min;

[0028] After the electrolysis, the product precipitated from the cathode is collected, washed with pure water for 3-5 times in a vacuum environment, then soaked in a saponification solution (50% sodium fatty acid, 10% sodium dodecyl benzene sulfonate, 2% sodium tripolyphosphate, 5% ethanol, 5% ethylene glycol and 2% sodium carbonate) for 5min. Then washed with pure water for 3 times, soaked in 20% benzotriazole for 10min. Then washed with pure water for 2 times, soaked in 5% disodium EDTA dihydrate for 15min, washed with pure water for 3 times, and then dehydrated, transferred to a vacuum drying oven at 343K for drying for 8-12h to obtain the coral-like copper powder.

[0029] Example 1

[0030] Silicotungstic acid, copper sulfate pentahydrate, sulfuric acid and pure water are mixed, wherein the concentration of silicotungstic acid in the mixed solution is 0.0007mol / L, the concentration of copper ion is 0.12mol / L, and the concentration of sulfuric acid is 1.3mol / L. Then the mixed solution is placed in a 50℃ container, the rotating speed is kept at 300r / min, and the solution is dissolved for 30min to obtain an electrolyte.

[0031] The electrolyte is placed in an electrolytic cell for electrolysis. Pure copper plate is used as cathode plate and anode plate, the area of the cathode and the anode is both 0.01m 2 , the electrolyte temperature is kept at 55℃, the distance between the cathode and the anode is 3cm, and the current density is 1200A / m 2 . The two electrodes are powered for electrolysis for 5min to precipitate electrolytic copper powder on the cathode.

[0032] The copper powder precipitated from the cathode is collected and washed with ultrapure water for 3-5 times, then subjected to saponification and antioxidant treatment, and then vacuum dried at 60℃ for 12h before being sealed with nitrogen.

[0033] Figure 1 This is a SEM image of the copper powder prepared in this embodiment. Figure 1 The copper powder appears to be a fluffy coral-like structure with a clear main trunk. Long, slender columnar dendrites, radiating from the main axis, further extend outwards, with each branch being uniform in length and size. Numerous branches exist, and each slender cylindrical dendrite has a uniform diameter, resulting in an overall fluffy coral-like morphology. Measurements show that the copper powder has a particle size ranging from 5.24 μm to 8.87 μm, with an average particle size of 7.15 μm. The loose bulk density of the copper powder, measured using a funnel-type powder density meter, is 0.34 g / cm³. 3 (The same applies below) The purity of the copper powder was measured to be 99.9% using ICP (the same applies below).

[0034] Example 2

[0035] Silicotungstic acid, copper sulfate pentahydrate, sulfuric acid, and pure water were mixed, with the following concentrations: 0.0005 mol / L silicotungstic acid, 0.13 mol / L copper ions, and 1.4 mol / L sulfuric acid. The mixture was then placed in a container at 50°C and rotated at 300 rpm for 30 minutes to dissolve, yielding the electrolyte.

[0036] Electrolysis is carried out in an electrolytic cell with the electrolyte placed in it. Pure copper plates are used as both the cathode and anode plates, with each having an area of ​​0.01 m². 2 Maintain the electrolyte temperature at 55℃, the distance between the anode and cathode at 4cm, and the current density at 1200A / m. 2 Electrolysis was performed by passing current through the two electrodes for 5 minutes, and electrolytic copper powder was deposited on the cathode.

[0037] The copper powder deposited from the cathode was collected and washed 3 to 5 times with ultrapure water. After saponification and anti-oxidation treatment, it was vacuum dried at 60°C for 12 hours and then sealed and stored in nitrogen.

[0038] Figure 2 This is a SEM image of the copper powder prepared in this embodiment. Figure 2 As can be seen, the copper powder is loose and coral-like, with a morphology similar to that of Example 1. Measurements showed that the particle size of the copper powder ranged from 6.31 μm to 9.46 μm, with an average particle size of 7.82 μm. The loose packing density of the copper powder was 0.44 g / cm³. 3 The purity is 99.9%.

[0039] Example 3

[0040] Silicotungstic acid, copper sulfate pentahydrate, sulfuric acid, and pure water were mixed, with the following concentrations: 0.001 mol / L silicotungstic acid, 0.14 mol / L copper ions, and 1.5 mol / L sulfuric acid. The mixture was then placed in a container at 50°C and rotated at 300 rpm for 30 minutes to dissolve, yielding the electrolyte.

[0041] Electrolysis is carried out in an electrolytic cell with the electrolyte placed in it. Pure copper plates are used as both the cathode and anode plates, with each having an area of ​​0.01 m². 2 Maintain the electrolyte temperature at 52℃, the distance between the anode and cathode at 5cm, and the current density at 1200A / m. 2 Electrolysis was performed by passing current through the two electrodes for 5 minutes, and electrolytic copper powder was deposited on the cathode.

[0042] The copper powder deposited from the cathode was collected and washed 3 to 5 times with ultrapure water. After saponification and anti-oxidation treatment, it was vacuum dried at 60°C for 12 hours and then sealed and stored in nitrogen.

[0043] Figure 3 This is a SEM image of the copper powder prepared in this embodiment. Figure 3 As can be seen, the copper powder is loose and coral-like, with a morphology similar to that of Example 1. Measurements showed that the particle size of the copper powder ranged from 5.26 μm to 7.58 μm, with an average particle size of 6.89 μm. The loose packing density of the copper powder was 0.31 g / cm³. 3 The purity is 99.9%.

[0044] Example 4

[0045] Copper silicotungstenate, copper sulfate pentahydrate, sulfuric acid, and pure water were mixed, with the concentrations of copper silicotungstenate (0.0003 mol / L), copper ions (0.11 mol / L), and sulfuric acid (1.3 mol / L) in the mixture. The mixture was then placed in a container at 50°C and rotated at 300 rpm for 30 minutes to dissolve, yielding the electrolyte.

[0046] Electrolysis is carried out in an electrolytic cell with the electrolyte placed in it. Pure copper plates are used as both the cathode and anode plates, with each having an area of ​​0.01 m². 2 Maintain the electrolyte temperature at 55℃, the distance between the anode and cathode at 3cm, and the current density at 1200A / m. 2 Electrolysis was performed by passing current through the two electrodes for 5 minutes, and electrolytic copper powder was deposited on the cathode.

[0047] The copper powder deposited from the cathode was collected and washed 3 to 5 times with ultrapure water. After saponification and anti-oxidation treatment, it was vacuum dried at 60°C for 12 hours and then sealed and stored in nitrogen.

[0048] Figure 4The morphology of the copper powder obtained in this embodiment is similar to that of the copper powder prepared in Example 1, also exhibiting a fluffy, coral-like appearance. Measurements showed that the particle size of this copper powder ranged from 7.43 μm to 9.69 μm, with an average particle size of 8.56 μm. The loose bulk density of the copper powder was 0.48 g / cm³. 3 The purity is 99.9%.

[0049] Comparative Example 1

[0050] Copper sulfate pentahydrate, sulfuric acid, and pure water were mixed to obtain a solution with a copper ion concentration of 0.12 mol / L and a sulfuric acid concentration of 1.3 mol / L. The solution was then placed in a container at 50°C and rotated at 300 rpm for 30 minutes to dissolve, yielding the electrolyte. Pure copper plates were used as both the cathode and anode, with an area of ​​0.01 m². 2 Maintain the electrolyte temperature at 55℃, the distance between the anode and cathode at 3cm, and the current density at 1200A / m. 2 Electrolysis was performed by passing an electric current through the two electrodes for 5 minutes, resulting in the deposition of electrolytic copper powder on the cathode. The copper powder deposited on the cathode was collected and washed 3-5 times with ultrapure water. After saponification and anti-oxidation treatment, it was vacuum dried at 60°C for 12 hours and then stored in a nitrogen-sealed container.

[0051] SEM images of the prepared electrolytic copper powder are shown below. Figure 5 As shown. From Figure 5 It can be seen that the copper powder prepared in this comparative example is corn-shaped and lacks well-developed, elongated dendrites. Measurements showed that the particle size of the copper powder ranged from 7.55 μm to 16.69 μm, with an average particle size of 12.37 μm and a loose packing density of 1.3 g / cm³. 3 The purity of the electrolytic copper powder is 99.9%.

[0052] pass Figures 1 to 5 The comparison shows that, compared with the corn-like copper powder prepared in Comparative Example 1, the copper powder prepared in Examples 1-4 has significantly more developed and interlocking slender dendrites, resulting in a more complex geometric structure, greater surface roughness, larger specific surface area, and more contact sites. Consequently, it possesses a larger specific surface area, higher electrical conductivity, thermal conductivity, hydrophobicity, compressibility, and formability, as well as better processability and lower bulk density. The role of additive S is that the presence of silicotungstic acid ions causes copper ions to preferentially grow on the (331) crystal plane when they are converted into copper grains. Under the conditions of optimized electrolyte formulation and electrolysis process, fluffy coral-like copper powder can be stably prepared.

[0053] It can be seen that the copper powder prepared by the method provided by the present application has a fluffy coral appearance, a particle size of 4-10 μm, and long and thin columnar branches produced from the main shaft are further unfolded, and the length and size of each long and thin columnar branch are uniformly distributed. Since the copper powder has a fluffy coral appearance, it has a more complex geometric structure, a larger surface roughness, a larger specific surface area and more contact points, and thus has higher conductivity, thermal conductivity, compressibility and formability, and better processability and chemical stability. The loose bulk density of the copper powder is 0.30-0.50 g / cm 3 A smaller loose bulk density can have a higher specific surface area and adsorption capacity, is easier to form a porous structure, and reduces the amount of electrolytic copper powder used in actual production, thereby reducing the use cost.

[0054] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application belong to the scope of the claims of the present application and equivalent technologies thereof, the present application also intends to include these modifications and variations.

Claims

1. A method for preparing coral-like copper powder, characterized in that, Includes the following steps, Additive S, CuSO4·5H2O, H2SO4 and pure water are mixed to form a solution; the solution is transferred to a stirrer at 40~60 ℃ and the speed is maintained at 300~480 r / min for 30~60 min to dissolve, thus obtaining the electrolyte; Electrolysis is carried out in an electrolytic cell with the electrolyte placed in it; pure copper plates are used as the anode and cathode, the distance between the anode and cathode is controlled to be 3-5 cm, and the working electrode area is 0.01-1 m². 2 The electrolyte temperature is 40~60 ℃, and the current density is 1200~1600 A / m. 2 The electrolysis time is 5-8 minutes; After electrolysis, the product deposited at the cathode is collected, washed with pure water 3 to 5 times, and after saponification and anti-oxidation treatment, it is vacuum dried at 60 ℃ for 8 to 12 h to obtain coral-like copper powder. In the solution, the concentration of copper ions is 0.10~0.15 mol / L, the concentration of sulfuric acid is 1.2~1.6 mol / L, and the concentration of additive S is 0.0003~0.001 mol / L; The additive S is silicotungstic acid or silicotungstate.

2. The method for preparing coral-like copper powder according to claim 1, characterized in that, The silicotungstic acid salt is a soluble silicotungstic acid salt.

3. The method for preparing coral-like copper powder according to claim 2, characterized in that, The silicotungstate is copper silicotungstate.

4. The method for preparing coral-like copper powder according to claim 1, characterized in that, The electrolyte temperature is 55°C.

5. A copper powder, characterized in that, The copper powder is prepared using the method described in claim 1; the copper powder has a coral-like morphology and a loose bulk density of 0.30~0.50 g / cm³. 3 The particle size is 4~10µm and the purity is 99.9%.

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