A method for controllably preparing core-shell type silver-copper powder by electroplating composite chemical plating

Abstract

The invention discloses a method for controllably preparing core-shell silver-copper powder by electrodeposition composite chemical plating, which comprises sequentially electrodeposition of copper, physical passivation, electrodeposition of silver, chemical silver plating and integrated post-treatment. The invention proposes a method for controllably preparing core-shell silver-copper powder by electrodeposition composite chemical plating. Compared with other conventional preparation processes, the method has the advantages of short process, simple operation, precise control of microscopic morphology, suitability for continuous production, and microscopically controllable preparation of ultrafine core-shell silver-coated copper powder.

Description

Technical Field

[0001] The invention relates to the technical field of conductive materials, in particular to a controllable preparation method of core-shell type ultrafine silver-coated copper powder by electro-deposition composite chemical plating. Background Art

[0002] Precious metal silver is widely used in electronics, petrochemicals, industrial catalysis, pharmaceutical antibacterial, jewelry and other fields due to its good electrical properties, thermal properties and processing properties. As the main raw material in the photovoltaic field, the microscopic controllable preparation technology of photovoltaic silver powder is relatively difficult and the iteration speed is relatively fast. As a major industrial country in the global photovoltaic field, my country has a large demand for photovoltaic silver powder. It is currently in the window period of domestic substitution and the period of domestic production capacity release. However, as a precious metal, silver has a high value, which is directly reflected in the comprehensive cost of photovoltaic power generation. How to reduce the use of silver is one of the focuses of the photovoltaic field, and it is also an important link in achieving cost reduction and efficiency improvement in the photovoltaic field.

[0003] Silver-coated copper can effectively reduce the amount of silver used and is currently one of the important directions for reducing the cost of photovoltaic silver powder. Traditional silver-coated copper powder preparation technology mostly uses chemical reduction method, which has the following shortcomings: First, the reaction process is difficult to accurately control, and the surface of microscopic copper particles cannot be 100% coated with silver, and is partially exposed, which affects the conductivity of the slurry after printing; second, batch stability needs to be improved. At present, the microscopic morphology of silver-coated copper powder in large-scale industrial production is difficult to accurately control, which affects the performance of downstream slurry. Therefore, in order to further meet the development needs of the photovoltaic industry and reduce the cost of photovoltaic power generation, it is urgent to develop a controllable preparation method for core-shell ultrafine silver-coated copper powder suitable for large-scale production. Summary of the invention

[0004] The main purpose of the present invention is to solve the problems existing in the above-mentioned traditional chemical reduction method, and to provide a microscopically controllable preparation method of ultrafine core-shell type silver-coated copper powder with short process, simple operation, precise control of microscopic morphology and suitable for continuous production.

[0005] In order to solve the above technical problems, the solution provided by the present invention is a method for preparing core-shell type silver-copper powder by composite chemical plating with electrodeposition, comprising the following steps:

[0006] (1) Electrodeposition of copper: Add the prepared copper sulfate electrolyte to the copper electrolytic cell, hang a 99.5% anode copper plate on the anode rod, use a titanium-plated stainless steel plate as the cathode, connect a DC power supply, the cell voltage is 0.2-0.3V, the electrolyte temperature is constant at 60°C, ultrafine copper powder is precipitated on the cathode plate, remove the cathode plate after the electrodeposition is completed, and the copper electrolyte is recycled after purification;

[0007] (2) Physical passivation: Place the cathode plate covered with ultrafine copper powder into a transfer tank filled with a passivation protective agent PVP solution for physical passivation treatment. After the passivation treatment is completed, take out the cathode plate;

[0008] (3) Electrodeposition of silver: hang the passivated cathode plate covered with ultrafine copper powder into the silver electrolytic cell, hang the anode silver plate on the anode rod, slowly add the prepared silver nitrate electrolyte, connect the DC power supply, keep the cell voltage at 5V, and keep the electrolyte temperature at 40-60°C. The ultrafine silver powder precipitated on the cathode plate will coat the underlying copper powder. The solid phase powder on the cathode plate will be scraped off by the reciprocating motion of the stirring rod between the anode and the cathode. After the electrodeposition is completed, the silver electrolyte and the solid phase powder will be transferred to the solid-liquid separator. The solid phase powder and the silver electrolyte will be separated by negative pressure filtration. The silver electrolyte will be recycled after purification.

[0009] (4) Chemical silver plating: Add the solid phase powder to a mixed solution containing an oxidizing agent, silver nitrate, and a dispersing agent, PVP, and stir at 100 to 200 r / min for 10 to 30 min. Add a reducing agent, vitamin C solution, and precisely control the chemical silver plating on the surface of the ultrafine copper powder that is not coated with electrodeposited silver. After the reaction is completed, transfer the silver-coated copper powder and the reaction solution to a solid-liquid separator, and separate the silver-coated copper powder and the reaction solution by negative pressure filtration.

[0010] (5) Integrated post-treatment: adding anhydrous ethanol to the silver-coated copper powder for washing, dispersing the washed silver-coated copper powder with an organic dispersant, placing the dispersed silver-coated copper powder in a forced air drying oven, and drying it at a drying temperature of 60 to 80°C for 8 to 12 hours to prepare a core-shell type silver-copper powder with controllable micromorphology.

[0011] Preferably, in step (1), the mass concentration of copper sulfate in the copper sulfate electrolyte is 30 to 60 g / L.

[0012] Preferably, in step (2), the mass concentration of PVP in the passivation protective agent PVP solution is 10 to 30 g / L.

[0013] Preferably, in step (3), Ag in the silver nitrate electrolyte + The mass concentration is 150~200 g / L.

[0014] Preferably, in step (4), Ag in the mixed solution + The mass concentration is 100~160 g / L.

[0015] Preferably, in step (4), the mass concentration of PVP in the mixed solution is 25-40 g / L.

[0016] Preferably, in step (4), the mass concentration of vitamin C in the vitamin C solution is 70 to 140 g / L.

[0017] Preferably, in step (5), the ratio of anhydrous ethanol to silver-coated copper powder is (2-4) mL:1 g.

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

[0019] 1. The present invention is different from the traditional chemical reduction preparation technology of silver-coated copper powder, and proposes a method for preparing core-shell type silver-copper powder by electrodeposition composite chemical plating; compared with the existing chemical reduction preparation technology, the present invention has a short process, simple operation, precise control of micromorphology, and is suitable for continuous production.

[0020] 2. The present invention proposes a composite step-by-step operation of electroplating copper and silver + chemical silver plating, and adds a passivation treatment, which can accurately control the growth process and surface micromorphology of solid phase particles during each step of the operation, and effectively solve the problem of difficult control of the surface micromorphology of silver-coated copper powder in the final link.

[0021] 3. Different from other silver-coated copper powder preparation systems, the intermediate products in the whole operation process of the present invention do not need to be washed with deionized water, and the amount of wastewater generated is greatly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the preparation process of the present invention;

[0023] Figure 2 is a scanning electron microscope image of the silver-coated copper powder prepared in Example 1 of the present invention;

[0024] Figure 3 is a scanning electron microscope image of the silver-coated copper powder prepared in Example 2 of the present invention;

[0025] Figure 4 This is a scanning electron microscope image of the silver-coated copper powder prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] The method for preparing core-shell type silver-copper powder by composite chemical plating by electrodeposition in this embodiment comprises the following steps:

[0028] (I) Electrolytic deposition of copper: Add copper sulfate electrolyte with a mass concentration of 30g / L into the copper electrolytic cell, hang a 99.5% anode copper plate on the anode rod, use a titanium-plated stainless steel plate as the cathode, connect a DC power supply, the cell voltage is 0.2V, the electrolyte temperature is constant at 60°C, ultrafine copper powder is precipitated on the cathode plate, and the cathode plate is slowly removed after the electrodeposition is completed. The copper electrolyte is recycled after purification.

[0029] (ii) Physical passivation: slowly place the cathode plate covered with ultrafine copper powder into a transfer tank filled with a 10g / L passivation protective agent PVP solution for physical passivation treatment. After the passivation treatment is completed, slowly take out the cathode plate.

[0030] (III) Electrodeposition of silver: Hang the passivated cathode plate covered with ultrafine copper powder into the silver electrolytic cell, hang the anode silver plate on the anode rod, and slowly add Ag + A silver nitrate electrolyte with a mass concentration of 150g / L is connected to a DC power supply, a constant cell voltage of 5V, and an electrolyte temperature of 40°C. The ultrafine silver powder precipitated on the cathode plate coats the underlying copper powder, and the solid phase powder on the cathode plate is scraped off by the reciprocating motion of the stirring rod between the anode and the cathode. After the electrodeposition is completed, the silver electrolyte and the solid phase powder are transferred to a solid-liquid separator, and the solid phase powder and the silver electrolyte are separated by negative pressure filtration. The silver electrolyte is recycled after purification.

[0031] (IV) Chemical silver plating: Add the solid powder into a mixed solution of 100 g / L silver nitrate as an oxidant and 25 g / L PVP as a dispersant, stir at 100 r / min for 10 min, add 70 g / L vitamin C solution as a reducing agent, and precisely control the chemical silver plating on the surface of the ultrafine copper powder in the area not coated by the electrodeposited silver. After the reaction is completed, transfer the silver-coated copper powder and the reaction solution to a solid-liquid separator, and separate the silver-coated copper powder and the reaction solution by negative pressure filtration.

[0032] (V) Integrated post-processing: adding anhydrous ethanol to the silver-coated copper powder for cleaning, the volume mass ratio of anhydrous ethanol to the silver-coated copper powder is 2:1, and dispersing the washed silver-coated copper powder with an organic dispersant. The dispersed silver-coated copper powder is placed in a forced air drying oven and dried at 60°C for 8 hours to prepare silver-coated copper powder with controllable micromorphology.

[0033] The obtained ultrafine core-shell silver-coated copper powder has a scanning electron microscope image as shown in Figure 2 As shown, the D50 of the prepared silver-coated copper powder was determined to be 1.8 μm by laser particle size distribution detection method.

[0034] Example 2

[0035] The method for preparing core-shell type silver-copper powder by composite chemical plating by electrodeposition in this embodiment comprises the following steps:

[0036] (I) Electrolytic deposition of copper: Add copper sulfate electrolyte with a mass concentration of 40g / L into the copper electrolytic cell, hang a 99.5% anode copper plate on the anode rod, use a titanium-plated stainless steel plate as the cathode, connect a DC power supply, the cell voltage is 0.3V, the electrolyte temperature is constant at 60°C, ultrafine copper powder is precipitated on the cathode plate, and the cathode plate is slowly removed after the electrodeposition is completed. The copper electrolyte is recycled after purification.

[0037] (ii) Physical passivation: slowly place the cathode plate covered with ultrafine copper powder into a transfer tank filled with a 20g / L passivation protective agent PVP solution for physical passivation treatment. After the passivation treatment is completed, slowly take out the cathode plate.

[0038] (III) Electrodeposition of silver: Hang the passivated cathode plate covered with ultrafine copper powder into the silver electrolytic cell, hang the anode silver plate on the anode rod, and slowly add Ag + A silver nitrate electrolyte with a mass concentration of 170g / L is connected to a DC power supply, a constant cell voltage of 5V, and an electrolyte temperature of 50°C. The ultrafine silver powder precipitated on the cathode plate coats the underlying copper powder, and the solid phase powder on the cathode plate is scraped off by the reciprocating motion of the stirring rod between the anode and the cathode. After the electrodeposition is completed, the silver electrolyte and the solid phase powder are transferred to a solid-liquid separator, and the solid phase powder and the silver electrolyte are separated by negative pressure filtration. The silver electrolyte is purified and recycled.

[0039] (IV) Chemical silver plating: Add the solid powder into a mixed solution of 130 g / L silver nitrate as an oxidant and 35 g / L PVP as a dispersant, stir at 150 r / min for 20 min, add 100 g / L vitamin C solution as a reducing agent, and precisely control the chemical silver plating on the surface of the ultrafine copper powder in the area not coated by the electrodeposited silver. After the reaction is completed, transfer the silver-coated copper powder and the reaction solution to a solid-liquid separator, and separate the silver-coated copper powder and the reaction solution by negative pressure filtration.

[0040] (V) Integrated post-processing: adding anhydrous ethanol to the silver-coated copper powder for cleaning, the volume mass ratio of anhydrous ethanol to silver-coated copper powder is 3:1, using an organic dispersant to disperse the washed silver-coated copper powder, placing the dispersed silver-coated copper powder in a forced air drying oven, and drying it at 70°C for 10 hours to prepare silver-coated copper powder with controllable micromorphology.

[0041] The obtained ultrafine core-shell silver-coated copper powder has a scanning electron microscope image as shown in Figure 3 As shown, the D50 of the prepared silver-coated copper powder was measured to be 2.6 μm by laser particle size distribution detection method.

[0042] Example 3

[0043] The method for preparing core-shell type silver-copper powder by composite chemical plating by electrodeposition in this embodiment comprises the following steps:

[0044] (I) Electrolytic deposition of copper: Add copper sulfate electrolyte with a mass concentration of 60g / L into the copper electrolytic cell, hang a 99.5% anode copper plate on the anode rod, use a titanium-plated stainless steel plate as the cathode, connect a DC power supply, the cell voltage is 0.3V, the electrolyte temperature is constant at 60°C, ultrafine copper powder is precipitated on the cathode plate, and the cathode plate is slowly removed after the electrodeposition is completed. The copper electrolyte is recycled after purification.

[0045] (ii) Physical passivation: slowly place the cathode plate covered with ultrafine copper powder into a transfer tank filled with a 30g / L passivation protective agent PVP solution for physical passivation treatment. After the passivation treatment is completed, slowly take out the cathode plate.

[0046] (III) Electrodeposition of silver: Hang the passivated cathode plate covered with ultrafine copper powder into the silver electrolytic cell, hang the anode silver plate on the anode rod, and slowly add Ag + A silver nitrate electrolyte with a mass concentration of 200g / L is connected to a DC power supply, a constant cell voltage of 5V, and an electrolyte temperature of 60°C. The ultrafine silver powder precipitated on the cathode plate coats the underlying copper powder, and the solid phase powder on the cathode plate is scraped off by the reciprocating motion of the stirring rod between the anode and the cathode. After the electrodeposition is completed, the silver electrolyte and the solid phase powder are transferred to a solid-liquid separator, and the solid phase powder and the silver electrolyte are separated by negative pressure filtration. The silver electrolyte is recycled after purification.

[0047] (IV) Chemical silver plating: Add the solid powder into a mixed solution of 160 g / L silver nitrate as an oxidant and 40 g / L PVP as a dispersant, stir at 200 r / min for 30 min, add 140 g / L vitamin C solution as a reducing agent, and precisely control the chemical silver plating on the surface of the ultrafine copper powder in the area not coated by the electrodeposited silver. After the reaction is completed, transfer the silver-coated copper powder and the reaction solution to a solid-liquid separator, and separate the silver-coated copper powder and the reaction solution by negative pressure filtration.

[0048] (V) Integrated post-processing: adding anhydrous ethanol to the silver-coated copper powder for cleaning, the volume mass ratio of anhydrous ethanol to silver-coated copper powder is 4:1, using an organic dispersant to disperse the washed silver-coated copper powder, placing the dispersed silver-coated copper powder in a forced air drying oven, and drying it at 80°C for 12 hours to prepare silver-coated copper powder with controllable micromorphology.

[0049] The obtained ultrafine core-shell silver-coated copper powder has a scanning electron microscope image as shown in Figure 4 As shown, the D50 of the prepared silver-coated copper powder was measured to be 2.3 μm by laser particle size distribution detection method.

[0050] It should be noted that the above embodiments all belong to the same inventive concept, and the description of each embodiment has its own focus. For matters that are not described in detail in some embodiments, reference may be made to the description in other embodiments.

[0051] The above-mentioned embodiments only express the implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing core-shell type silver-copper powder by electroplating composite chemical plating, characterized in that: The steps include: (1) Electrodeposition of copper: Add the prepared copper sulfate electrolyte to the copper electrolytic cell, hang a 99.5% anode copper plate on the anode rod, use a titanium-plated stainless steel plate as the cathode, connect a DC power supply, the cell voltage is 0.2-0.3V, the electrolyte temperature is constant at 60°C, ultrafine copper powder is precipitated on the cathode plate, remove the cathode plate after the electrodeposition is completed, and the copper electrolyte is recycled after purification; (2) Physical passivation: Place the cathode plate covered with ultrafine copper powder into a transfer tank filled with a passivation protective agent PVP solution for physical passivation treatment. After the passivation treatment is completed, take out the cathode plate; (3) Electrodeposition of silver: hang the passivated cathode plate covered with ultrafine copper powder into the silver electrolytic cell, hang the anode silver plate on the anode rod, slowly add the prepared silver nitrate electrolyte, connect the DC power supply, keep the cell voltage at 5V, and keep the electrolyte temperature at 40-60°C. The ultrafine silver powder precipitated on the cathode plate will coat the underlying copper powder. The solid phase powder on the cathode plate will be scraped off by the reciprocating motion of the stirring rod between the anode and the cathode. After the electrodeposition is completed, the silver electrolyte and the solid phase powder will be transferred to the solid-liquid separator. The solid phase powder and the silver electrolyte will be separated by negative pressure filtration. The silver electrolyte will be recycled after purification. (4) Chemical silver plating: Add the solid phase powder to a mixed solution containing an oxidizing agent, silver nitrate, and a dispersing agent, PVP, and stir at 100 to 200 r / min for 10 to 30 min. Add a reducing agent, vitamin C solution, and precisely control the chemical silver plating on the surface of the ultrafine copper powder that is not coated with electrodeposited silver. After the reaction is completed, transfer the silver-coated copper powder and the reaction solution to a solid-liquid separator, and separate the silver-coated copper powder and the reaction solution by negative pressure filtration. (5) Integrated post-treatment: adding anhydrous ethanol to the silver-coated copper powder for washing, dispersing the washed silver-coated copper powder with an organic dispersant, placing the dispersed silver-coated copper powder in a forced air drying oven, and drying it at a drying temperature of 60 to 80°C for 8 to 12 hours to prepare a core-shell type silver-copper powder with controllable micromorphology.

2. The method for controllably preparing core-shell type silver-copper powder by electrodeposition composite chemical plating according to claim 1, characterized in that: In the step (1), the mass concentration of copper sulfate in the copper sulfate electrolyte is 30 to 60 g / L.

3. The method for controllably preparing core-shell type silver-copper powder by electrodeposition composite chemical plating according to claim 1, characterized in that: In the step (2), the mass concentration of PVP in the passivation protective agent PVP solution is 10 to 30 g / L.

4. The method for controllably preparing core-shell type silver-copper powder by electrodeposition composite chemical plating according to claim 1, characterized in that: In the step (3), Ag in the silver nitrate electrolyte + The mass concentration is 150~200 g / L.

5. The method for controllably preparing core-shell type silver-copper powder by electrodeposition composite chemical plating according to claim 1, characterized in that: In the step (4), Ag in the mixed solution + The mass concentration is 100~160 g / L.

6. The method for controllably preparing core-shell type silver-copper powder by electrodeposition composite chemical plating according to claim 1, characterized in that: In the step (4), the mass concentration of PVP in the mixed solution is 25-40 g / L.

7. The method for controllably preparing core-shell type silver-copper powder by electrodeposition composite chemical plating according to claim 1, characterized in that: In the step (4), the mass concentration of vitamin C in the vitamin C solution is 70 to 140 g / L.

8. The method for controllably preparing core-shell type silver-copper powder by electrodeposition composite chemical plating according to claim 1, characterized in that: In the step (5), the ratio of anhydrous ethanol to silver-coated copper powder is (2-4) mL:1 g.

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