Preparation method of copper powder with four-stage dendrite structure and copper powder

Abstract

The application discloses a preparation method of copper powder with four-stage dendrite structure. The preparation method comprises the following steps: dissolving an additive M, CuSO4*5H2O and H2SO4 in deionized water to obtain an electrolyte; placing the electrolyte in an electrolytic cell to perform electrolysis; after the electrolysis is completed, collecting copper powder precipitated from the cathode, cleaning the copper powder with deionized water, placing the copper powder in a benzotriazole solution to perform antioxidation coating, cleaning the copper powder with deionized water again, naturally filtering, dehydrating and taking out, and vacuum drying, so as to obtain the copper powder with four-stage dendrite structure. The application further discloses the copper powder prepared by using the preparation method. The application has the advantages of simple preparation method, easy operation and high safety. The copper powder prepared by using the method has developed dendrite crystals, and thus has large surface roughness and specific surface area.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of material preparation, in particular to a preparation method of copper powder with four-level dendritic structure and the copper powder. BACKGROUND

[0002] As a basic material indispensable to most new materials, copper powder is widely favored and has great development prospects due to its conductivity, ductility, moderate price and other characteristics. With the continuous development of new materials, more stringent requirements are put forward for the micro-morphology of copper powder. Dendritic macromolecular copper powder has been widely studied due to its large specific surface area and special micro-morphology. However, current research reports on different morphologies and particle sizes of copper powder mainly focus on spherical and rod-shaped, and there is little research on slender dendritic copper powder.

[0003] At present, the methods for preparing copper powder mainly include physical method and chemical method. The physical method is to realize the change from large to small by powder, and the main methods include atomization method, ball milling method, etc. The chemical method mainly generates new phases through oxidation-reduction reaction, and the required copper powder is obtained by controlling the nucleation and growth of the new phases, and the representative methods include vapor deposition method, liquid phase reduction method and electrolysis method, etc.

[0004] The principle of electrolytic method for preparing copper powder is to produce directional motion electrons, so that the dissolved copper (Cu 2+ ) is reduced, Cu 2+ migrates in the electrolyte and is reduced on the surface of the cathode, and is deposited on the surface of the cathode. Under a certain current density, dendritic copper powder can be deposited on the cathode. However, the dendritic copper powder prepared by the existing method by only adjusting the current density has few dendritic branches, the loose bulk density is usually 1.5-3.0 g / cm 3 , the appearance is mostly in the form of rice husk rather than dendritic, the surface roughness and specific surface area are small, the number of contact points between copper powder particles is small, and it is difficult to meet the use requirements.

[0005] The formation of dendritic morphology of copper powder is not only affected by electrolysis process parameters, but also related to the composition of electrolyte. How to prepare developed dendritic copper powder with three-level or four-level dendritic crystals by electrolysis is a technical problem to be solved by those skilled in the art. SUMMARY

[0006] In view of the above problems existing in the prior art, the purpose of the present application is to solve the problems of few dendritic branches and large loose bulk density of copper powder prepared by the existing electrolytic method, and to provide a preparation method of copper powder with four-level dendritic structure and the copper powder. The copper powder prepared by the method has developed dendritic crystals, and therefore has a large surface roughness and specific surface area.

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

[0008] A preparation method of copper powder with four-level dendrite structure, comprising the following steps,

[0009] Dissolve the additive M, CuSO4·5H2O and H2SO4 in deionized water to obtain an electrolyte;

[0010] Place the electrolyte in an electrolytic cell for electrolysis; wherein pure copper plates (copper plate purity ≥ 99.99%) are used as anodes and cathodes, the distance between the anode and the cathode is controlled to be 5-30 cm, preferably 5-10 cm, the electrolyte temperature is 313-333 K, the current density is 1000-2000 A / m 2 , and the electrolysis time is 10-30 min;

[0011] After electrolysis, collect the copper powder precipitated from the cathode, wash it with deionized water, place it in a benzotriazole solution for antioxidant coating, wash it with deionized water again, naturally filter and dehydrate, then take it out, vacuum dry, and obtain the copper powder with four-level dendrite structure.

[0012] As a preferred embodiment, the concentration of CuSO4·5H2O in the electrolyte is 20-80 g / L, the concentration of H2SO4 is 100-200 g / L, and the amount of additive M added is 0.5-1.0 g / L.

[0013] When the concentration of additive M is less than 0.5 g / L or more than 1.0 g / L, the morphology of the electrolytic copper powder changes from four-level dendrite to irregular single-level dendrite with small size and fragmentation. It is shown that a reasonable concentration of M is more beneficial to obtain developed dendritic copper powder, and too high or too low concentration of additive will cause the dendrite to break.

[0014] As a preferred embodiment, the concentration of CuSO4·5H2O in the electrolyte is 20-40 g / L, the concentration of H2SO4 is 120-150 g / L, and the amount of additive M added is 1.0 g / L. The dendritic copper powder obtained by adding 1 g / L of additive M has more developed dendrite arms.

[0015] As a preferred embodiment, the additive M is a mixture of oxalic acid and glycerol in a molar ratio of (2-3):1. The addition of M is obviously beneficial to the morphology of the electrolytic preparation of developed dendritic copper powder, and the additive can significantly reduce the bulk density of the electrolytic copper powder.

[0016] As a preferred embodiment, the additive M is a mixture of oxalic acid and glycerol in a molar ratio of 2:1.

[0017] As preferred, the collected copper powder is washed with deionized water for 4 times, then placed in a benzotriazole solution for antioxidation coating, washed with deionized water for 2 times, naturally filtered and dehydrated, and finally vacuum dried.

[0018] The application also provides a copper powder prepared by the method for preparing the copper powder with the four-stage dendrite structure, which has the four-stage dendrite structure, the main dendrite length of 11-25 μm, the secondary dendrite length of 8-20 μm, the tertiary dendrite length of 6-15 μm, and the four-stage dendrite length of 2-8 μm. The average particle size of the copper powder is 10-30 μm, and the four-stage dendrites are clearly visible.

[0019] Further, the average particle size of the copper powder is 10-30 μm, the loose bulk density is less than 0.4 g / cm 3 , and the purity is 99.99%.

[0020] Compared with the prior art, the application has the following advantages:

[0021] 1. The preparation method provided by the application establishes the synergistic effect of the combined additive and sulfate ions during electrolysis by adding the additive mixed by oxalic acid and glycerol in the electrolyte, improves the reduction rate of copper ions, the grain morphology, the structure orientation and the dispersibility during the electrolysis process, promotes the preferred orientation of the specific crystal face, and is more conducive to the directional growth of the developed dendrite copper powder, so that the copper powder with four-stage dendrites is prepared. The additive used is a hydrocarbon oxide, which avoids the influence of impurity ions introduced in the electrolysis process on the electrolysis process, thereby ensuring the high purity of the product. The purity of the electrolytic copper powder prepared by the method is more than 99.99%. The preparation method is simple, easy to operate, and safe, and is suitable for industrial production.

[0022] 2. The copper powder prepared by the method provided by the application has developed dendrite crystals, and the four-stage dendrites are clearly visible. The main dendrite length is 11-25 μm, the secondary dendrite length is 8-20 μm, the tertiary dendrite length is 6-15 μm, and the four-stage dendrite length is 2-8 μm. The average particle size of the copper powder is 10-30 μm, and the loose bulk density is less than 0.4 g / cm 3 . Since the copper powder prepared by the application has a developed dendrite morphology, it has a more complex geometric structure, a larger surface roughness, a larger specific surface area, and more contact points, so it has higher electrical conductivity, thermal conductivity, compressibility, and formability, and better processability and chemical stability. Smaller loose bulk density can have higher specific surface area and adsorption capacity, be easier to form a porous structure, and reduce the amount of electrolytic copper powder in actual production, thereby reducing the use cost. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1A schematic diagram of copper powder with four-level dendritic structure.

[0024] Figure 2 A morphology diagram of copper powder prepared in Example 1 of the present application.

[0025] Figure 3 A morphology diagram of copper powder prepared in Comparative Example 1.

[0026] Figure 4 A morphology diagram of copper powder prepared in Comparative Example 2. DETAILED DESCRIPTION

[0027] The present application provides a preparation method of copper powder with four-level dendritic structure, comprising the following steps,

[0028] The additive M is dissolved in deionized water together with CuSO4·5H2O and H2SO4 to obtain an electrolyte;

[0029] The electrolyte is placed in an electrolytic cell for electrolysis; wherein pure copper plates are used as anode and cathode, the distance between the anode and cathode is controlled to be 5-30 cm, the temperature of the electrolyte is 313-333 K, the current density is 1000-2000 A / m 2 , and the electrolysis time is 10-30 min;

[0030] After the electrolysis, the copper powder precipitated from the cathode is collected, washed with deionized water, coated with antioxidant in benzotriazole solution, washed with deionized water again, naturally filtered and dehydrated, taken out, and vacuum dried to obtain the copper powder with four-level dendritic structure. Figure 1 A schematic diagram of copper powder with four-level dendritic structure.

[0031] Example 1

[0032] Oxalic acid and glycerol are mixed in a molar ratio of 2:1 to obtain an additive M. The additive M is dissolved in deionized water together with CuSO4·5H2O and H2SO4 to obtain an electrolyte containing 1.0 g / L of the additive M, 25 g / L of CuSO4·5H2O and 130 g / L of H2SO4.

[0033] The electrolyte is placed in an electrolytic cell for electrolysis. Pure copper plates are used as anode and cathode, the distance between the anode and cathode is controlled to be 6 cm, the electrolysis time is 10 min, the temperature of the electrolyte is 323 K, and the current density is 1200 A / m 2 .

[0034] After the electrolysis, the copper powder precipitated from the cathode is collected, washed with deionized water for 4 times, coated with antioxidant in benzotriazole (BTA) solution, washed with deionized water for 2 times, naturally filtered and dehydrated, taken out, and vacuum dried at 353 K to obtain the copper powder.

[0035] The morphology of the obtained copper powder is as follows Figure 2 As shown in the diagram, 1 represents a primary dendrite (main dendrite), 2 represents a secondary dendrite, 3 represents a tertiary dendrite, and 4 represents a quaternary dendrite. From... Figure 2 As can be seen from the analysis, the prepared copper powder exhibits well-developed dendritic crystals, with all quaternary dendrites clearly visible. Measurements showed that the main dendrite length was 11–19 μm, the secondary dendrite length was 8–11 μm, the tertiary dendrite length was 7–11 μm, and the quaternary dendrite length was 4–6 μm. The average particle size was 13.8 μm, and the copper powder purity (ICP-detected) was 99.99%. The loose bulk density of the copper powder, measured using the funnel method, was 0.36 g / cm³. 3 .

[0036] Example 2

[0037] Oxalic acid and glycerol were mixed in a molar ratio of 3:1 and denoted as additive M. Additive M was dissolved in deionized water along with CuSO4·5H2O and H2SO4 to obtain an electrolyte containing 1.2 g / L additive M, 30 g / L CuSO4·5H2O, and 140 g / L H2SO4.

[0038] Electrolysis was carried out in an electrolytic cell using a pure copper plate as both the anode and cathode. The electrode distance was controlled at 10 cm, the electrolysis time at 8 min, the electrolyte temperature at 323 K, and the current density at 1400 A / m. 2 .

[0039] After electrolysis, the copper powder deposited at the cathode is collected, washed five times with deionized water, then placed in benzotriazole (BTA) solution for antioxidant coating, washed twice with deionized water, naturally filtered and dehydrated, and then vacuum dried at 353K to obtain copper powder.

[0040] The morphology of the obtained copper powder was similar to that of Example 1. Measurements showed that the main dendrite length was 12–20 μm, the secondary dendrite length was 7–10 μm, the tertiary dendrite length was 8–13 μm, and the quaternary dendrite length was 3–5 μm. The average particle size was 14.4 μm, the purity was 99.99%, and the loose bulk density of the copper powder was 0.38 g / cm³. 3 .

[0041] Example 3

[0042] Oxalic acid and glycerol were mixed in a molar ratio of 3:1 and denoted as additive M. Additive M was dissolved in deionized water with CuSO4·5H2O and H2SO4 to obtain an electrolyte containing 1.5 g / L additive M, 35 g / L CuSO4·5H2O and 160 g / L H2SO4.

[0043] The electrolyte was placed in an electrolytic cell for electrolysis. Pure copper plates were used as anode and cathode, the distance between anode and cathode was controlled to be 10 cm, the electrolysis time was 15 min, the electrolyte temperature was 323 K, and the current density was 1600 A / m 2 .

[0044] After electrolysis, the copper powder precipitated from the cathode was collected, washed with deionized water for 4 times, then placed in a benzotriazole (BTA) solution for antioxidation coating, washed with deionized water for 2 times, naturally filtered and dehydrated, and then taken out and vacuum dried at 353 K to obtain the electrolytic copper powder.

[0045] The morphology of the prepared copper powder was similar to that of Example 1. It was measured that the primary dendrite length of the copper powder was 11-21 μm, the secondary dendrite length was 8-16 μm, the tertiary dendrite length was 8-13 μm, and the quaternary dendrite length was 4-7 μm. The average particle size was 15.5 μm, and the purity was 99.99%. The loose bulk density of the copper powder was 0.38 g / cm 3 .

[0046] Comparative Example 1

[0047] CuSO4-5H2O and H2SO4 were dissolved in deionized water to obtain an electrolyte containing 25 g / L of CuSO4-5H2O and 130 g / L of H2SO4.

[0048] The electrolyte was placed in an electrolytic cell for electrolysis. Pure copper plates were used as anode and cathode, the distance between anode and cathode was controlled to be 6 cm, the electrolysis time was 10 min, the electrolyte temperature was 323 K, and the current density was 1200 A / m 2 .

[0049] After electrolysis, the copper powder precipitated from the cathode was collected, washed with deionized water for 4 times, then placed in a benzotriazole (BTA) solution for antioxidation coating, washed with deionized water for 2 times, naturally filtered and dehydrated, and then taken out and vacuum dried at 353 K to obtain the electrolytic copper powder.

[0050] The morphology of the prepared copper powder was as shown in Figure 3 From the Figure 3 , it can be seen that the prepared copper powder had few dendrites, only appeared as a bract-like shape, and was not a tree-like shape. The loose bulk density of the copper powder was 1.2 g / cm 3 , the average particle size was 18.2 μm, and the purity was 99.99%.

[0051] Comparative Example 2

[0052] Oxalic acid and glycerol were mixed in a molar ratio of 2:1 to obtain an additive M. The additive M, CuSO4-5H2O and H2SO4 were dissolved in deionized water to obtain an electrolyte containing 4.0 g / L of the additive M, 25 g / L of CuSO4-5H2O and 130 g / L of H2SO4.

[0053] The electrolyte is placed in the electrolytic cell for electrolysis. The pure copper plate is used as the anode and cathode, the distance between the anode and cathode is controlled to be 6 cm, the electrolysis time is 10 min, the electrolyte temperature is 323 K, and the current density is 1200 A / m 2 .

[0054] After the electrolysis, the copper powder precipitated from the cathode is collected, washed with deionized water for 4 times, placed in the benzotriazole (BTA) solution for antioxidation coating, washed with deionized water for 2 times, naturally filtered, dehydrated, taken out, vacuum dried, and then the electrolytic copper powder is obtained.

[0055] The morphology of the prepared copper powder is shown in Figure 4 , and it can be seen from Figure 4 that the prepared copper powder has certain dendritic crystals, but the dendritic crystals are not developed, and only primary and secondary dendritic crystals exist. The primary dendritic crystal of the copper powder is 13-21 μm, the secondary dendritic crystal is 8-11 μm, and there is no tertiary dendritic crystal. The average particle size is 7.4 μm, the purity is 99.99%, and the loose bulk density is 0.62 g / cm 3 .

[0056] It can be seen that the copper powder prepared by the method provided by the present application has developed dendritic crystals, the primary dendritic crystal length is 11-25 μm, the secondary dendritic crystal length is 8-20 μm, the tertiary dendritic crystal length is 6-15 μm, and the quaternary dendritic crystal length is 2-8 μm. The average particle size of the copper powder is 10-30 μm, the loose bulk density is less than 0.4 g / cm 3 . The copper powder has more complex geometric structure, larger surface roughness, larger specific surface area and more contact points.

[0057] 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 the equivalent technologies thereof, the present application also intends to include these modifications and variations.

Claims

1. A method for producing copper powder having a quaternary dendrite structure, characterized by, The method comprises the following steps, The additive M is dissolved in CuSO4·5H2O and H2SO4 in deionized water to obtain an electrolyte; The electrolyte is placed in an electrolytic cell for electrolysis; wherein pure copper plates are used as anode and cathode, the distance between anode and cathode is controlled to be 5-30 cm, the temperature of electrolyte is 313-333 K, the current density is 1000-2000 A / m 2 , and the electrolysis time is 10-30 min. After electrolysis, the copper powder separated from the cathode is collected, washed with deionized water, coated with antioxidant in benzotriazole solution, washed with deionized water again, naturally filtered and dehydrated, taken out and vacuum dried to obtain the copper powder with four-level dendritic structure. The concentration of CuSO4·5H2O in the electrolyte is 20-80 g / L, the concentration of H2SO4 is 100-200 g / L, the additive M is a mixture of oxalic acid and glycerol in a molar ratio of 2-3:1, and the additive M is added in an amount of 0.5-1.0 g / L.

2. The method for preparing copper powder with a fourth-order dendritic structure according to claim 1, characterized in that, The concentration of CuSO4·5H2O in the electrolyte is 20-40 g / L, the concentration of H2SO4 is 120-150 g / L, and the additive M is added in an amount of 1.0 g / L.

3. The method for preparing copper powder with a fourth-order dendritic structure according to claim 1, characterized in that, The additive M is a mixture of oxalic acid and glycerol in a molar ratio of 2:

1.

4. The method for preparing copper powder with a fourth-order dendritic structure according to claim 1, characterized in that, The collected copper powder is washed with deionized water for 4 times, coated with antioxidant in benzotriazole solution, washed with deionized water for 2 times, naturally filtered and dehydrated, taken out and finally vacuum dried.

5. A copper powder produced by the method of producing a copper powder having a quaternary dendrite structure according to any one of claims 1 to 4, characterized by The copper powder has four-level dendritic structure, the length of the primary dendrite is 11-25 μm, the length of the secondary dendrite is 8-20 μm, the length of the tertiary dendrite is 6-15 μm, and the length of the four-level dendrite is 2-8 μm.

6. The copper powder of claim 5, wherein, The average particle size of the copper powder is 10-30 μm, and the loose bulk density is less than 0.4 g / cm 3 with a purity of 99.99%.

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