A method for preparing silver-copper alloy powder

Abstract

The application discloses a preparation method of silver-copper alloy powder, and comprises the following steps: weighing a proper amount of dispersing agent, dissolving the dispersing agent in deionized water to obtain a reaction bottom solution, preparing a copper nitrate solution and a reducing agent solution, adding a glucose solution to pre-reduce, adding an L-ascorbic acid solution to reduce, preparing elemental copper metal powder in two steps, increasing the temperature of a reaction kettle, adding a silver nitrate solution drop by drop, lowering the temperature of the reaction kettle after the replacement reaction is completed, and adding the L-ascorbic acid solution drop by drop until the reaction is completed; the silver-copper alloy powder prepared by the method has the characteristics of uniform particle size and good dispersity, can be used for large-scale production of copper-silver alloy, and can be applied to various fields.

Description

Technical Field

[0001] This invention belongs to the field of precious metal powder material preparation technology, and relates to a method for preparing ultrafine silver-copper alloy powder. Background Technology

[0002] Silver has the highest electrical and thermal conductivity of all metals, and it is the cheapest of the precious metals. Silver also has good machinability. Adding copper increases the hardness and tensile strength of the material, while also providing good electrical conductivity. Silver-copper alloys with a copper content of 5%–30% exhibit good fluidity, wettability, and low vapor pressure, making them excellent filler metals for electro-vacuum soldering. Silver and silver-copper alloys are the most widely used electrical contact materials. The quality of parameters such as grain size, morphology, grain size distribution, tap density, and surface condition of silver-copper alloys significantly affects their performance.

[0003] Currently, silver-copper alloys are prepared using both physical and chemical methods. Chemical methods are the primary method used for large-scale production due to their lower production costs and ease of control. However, silver-copper alloy powders prepared by chemical methods currently exhibit uneven particle size distribution and poor dispersibility. Summary of the Invention

[0004] To address the aforementioned problems and the shortcomings of existing silver-copper alloy powder preparation technologies, this invention provides a method for preparing ultrafine silver-copper alloy powder with a particle size of less than 1 micrometer, uniform particle size, and high dispersibility.

[0005] The technical solution adopted by this invention to solve its technical problem is: a method for preparing silver-copper alloy powder, comprising the following steps:

[0006] Step 1: Weigh 50g of polyvinylpyrrolidone K60 into the reaction vessel and dissolve it in 1L of deionized water. Add sodium hydroxide to adjust the pH of the solution to 2-6 as the reaction base solution. The mass of the dispersant polyvinylpyrrolidone K60 is 2-10% of the final silver-copper alloy powder mass.

[0007] Step 2: Weigh 210g of copper nitrate solution and add it dropwise to the reaction vessel. First, add 200g of glucose solution for pre-reduction, and then add 200g of L-ascorbic acid solution for reduction. The two steps are used to prepare elemental copper metal powder.

[0008] Step 3: Add silver nitrate solution dropwise to the reacted solution, while raising the temperature to 70-90℃, and replace the silver ions in the silver nitrate with elemental copper metal powder.

[0009] Step 4: After the displacement reaction is complete, cool the temperature to 25-30℃ and add L-ascorbic acid solution dropwise to the reaction vessel to reduce the displaced copper ions;

[0010] Step 5: After the reaction is complete, wash with deionized water and ethanol respectively, then separate the solid and liquid phases using a centrifuge, and dry in an oven at 45-80 ℃ to obtain a silver-copper alloy powder product with a D50 of 400-1200 nm.

[0011] In the preparation method of the silver-copper alloy powder, the concentration of the copper nitrate solution in step two is diluted 5 to 10 times by adding deionized water.

[0012] In the preparation method of the silver-copper alloy powder, in step two, the concentrations of glucose solution and L-ascorbic acid solution are diluted 10 to 30 times by adding deionized water.

[0013] In the preparation method of the silver-copper alloy powder, the molar ratio of metal ions to glucose solution and L-ascorbic acid solution in step two is 1:0.6-1.2.

[0014] In the preparation method of the silver-copper alloy powder, in step two, a peristaltic pump is used to add glucose solution and L-ascorbic acid solution to the reaction base liquid in two stages. The pre-reduction drop solution is added at a rate of 50 mL / min and the addition time is controlled to be 30-50% of the total time. The reduction drop solution is added at a rate of 200 mL / min and the addition time is controlled to be 50-70% of the total time.

[0015] In the preparation method of the silver-copper alloy powder, the molar ratio of metal ions to L-ascorbic acid solution in step four is 1:0.2-0.5.

[0016] The advantages and positive effects of this invention are as follows:

[0017] 1. The method of the present invention controls the particle size of copper powder by controlling the amount of sodium hydroxide added in the base solution and adjusting the pH value of the solution, and by utilizing the principle that the reducing agent has different reducing power under different acidity and alkalinity to carry out pre-reduction and reduction in two stages, thereby achieving the goal of controllable copper powder particle size.

[0018] 3. The method of the present invention uses a substitution method to generate active sites on the surface of the copper core with silver, so that the silver ions that are not completely substituted can be reduced on the surface of the copper through the active sites, thereby achieving the goal of uniform particle size. Attached Figure Description

[0019] Figure 1 SEM image of the spherical silver-copper powder prepared in Example 1;

[0020] Figure 2 SEM image of the spherical silver-copper powder prepared in Example 2;

[0021] Figure 3 The image shows a SEM image of the spherical silver-copper powder prepared in Example 2. Detailed Implementation

[0022] The present invention will be specifically described below through embodiments to further illustrate the invention, but this should not be construed as limiting the scope of protection of the present invention. Example 1

[0023] This embodiment discloses a method for preparing silver-copper alloy powder, which includes the following steps.

[0024] Step 1: Weigh 50g of polyvinylpyrrolidone K60 into the reaction vessel and dissolve it completely in 1L of deionized water; add sodium hydroxide to adjust the pH of the solution to 2, which will serve as the reaction base solution.

[0025] Step two: Weigh 210g of copper nitrate solution and 200g of glucose solution and add them dropwise to the reaction vessel. Using a peristaltic pump, prepare elemental copper powder in two steps: pre-reduction followed by the addition of 200g of L-ascorbic acid solution. The pre-reduction solution is added at a rate of 50 mL / min for 30-50% of the total time, while the reduction solution is added at a rate of 200 mL / min for 50-70% of the total time. The copper nitrate solution concentration is diluted 5-10 times with deionized water, and the glucose and L-ascorbic acid solutions are diluted 10-30 times with deionized water, ensuring a molar ratio of metal ions to glucose and L-ascorbic acid solutions of 1:0.6-1.2.

[0026] Step 3: Add 50g of silver nitrate solution to the reacted solution, and simultaneously raise the temperature to 70℃ to replace the silver ions in the silver nitrate with elemental copper.

[0027] Step four: After the displacement reaction is complete, lower the temperature to 25°C and add 50g of L-ascorbic acid solution dropwise to the reaction vessel to reduce the displaced copper ions. Ensure that the molar ratio of metal ions to L-ascorbic acid solution is 1:0.2-0.5.

[0028] Step 5: After the reaction is complete, wash with deionized water and ethanol respectively, then separate the solid and liquid phases using a centrifuge, and dry in an oven at a set temperature of 45 ℃ to obtain the final silver-copper alloy powder product.

[0029] Using SEM electron microscopy, such as Figure 1 The analysis shows that the obtained silver-copper powder has a D50 of approximately 1200 nm, with uniform particle size and good dispersibility. This invention, by adjusting process parameters, allows for controllable preparation of silver-copper particles, resulting in silver-copper alloy powder products with uniform particle size distribution and good dispersibility. The preparation method is simple and controllable, has low production costs, and is easily scalable for large-scale production. Example 2

[0030] This embodiment discloses a method for preparing silver-copper alloy powder, which includes the following steps.

[0031] Step 1: Weigh 50g of polyvinylpyrrolidone K60 into the reaction vessel and dissolve it completely in 1L of deionized water; add sodium hydroxide to adjust the pH of the solution to 4, which will serve as the reaction base solution.

[0032] Step 2: Weigh 210g of copper nitrate solution and 200g of glucose solution and add them dropwise to the reaction vessel. After pre-reduction, add 200g of L-ascorbic acid solution dropwise to reduce the copper metal powder in two steps. The pre-reduction drop rate is 50 mL / min, and the drop time is controlled to be 30-50% of the total time. The reduction drop rate is 200 mL / min, and the drop time is controlled to be 50-70% of the total time.

[0033] Step 3: Add 50g of silver nitrate solution to the reacted solution, and simultaneously raise the temperature to 80℃ to replace the silver ions in the silver nitrate with elemental copper.

[0034] Step 4: After the displacement reaction is complete, lower the temperature to 28°C and add 50g of L-ascorbic acid solution to the reaction vessel to reduce the displaced copper ions.

[0035] Step 5: After the reaction is complete, wash with deionized water and ethanol respectively, then separate the solid and liquid phases using a centrifuge, and dry in an oven at a set temperature of 60 ℃ to obtain the final silver-copper alloy powder product.

[0036] Using SEM electron microscopy, such as Figure 2 The analysis shows that the obtained silver-copper powder has a D50 of about 900 nm, with uniform particle size and good dispersibility. Example 3

[0037] This embodiment discloses a method for preparing silver-copper alloy powder, which includes the following steps.

[0038] Step 1: Weigh 50g of polyvinylpyrrolidone K60 into the reaction vessel and dissolve it completely in 1L of deionized water; add sodium hydroxide to adjust the pH of the solution to 6, which will serve as the reaction base solution.

[0039] Step 2: Weigh 210g of copper nitrate solution and 200g of glucose solution and add them dropwise to the reaction vessel. After pre-reduction, add 200g of L-ascorbic acid solution dropwise to reduce the copper metal powder in two steps. The pre-reduction drop rate is 50 mL / min, and the drop time is controlled to be 30-50% of the total time. The reduction drop rate is 200 mL / min, and the drop time is controlled to be 50-70% of the total time.

[0040] Step 3: Add 50g of silver nitrate solution to the reacted solution, and simultaneously raise the temperature to 90℃ to replace the silver ions in the silver nitrate with elemental copper.

[0041] Step 4: After the displacement reaction is complete, lower the temperature to 30°C and add 50g of L-ascorbic acid solution to the reaction vessel to reduce the displaced copper ions.

[0042] Step 5: After the reaction is complete, wash with deionized water and ethanol respectively, then separate the solid and liquid phases using a centrifuge, and dry in an oven at a set temperature of 80 ℃ to obtain the final silver-copper alloy powder product.

[0043] Using SEM electron microscopy, such as Figure 3 The analysis shows that the obtained silver-copper powder has a D50 of about 400 nm, with uniform particle size and good dispersibility.

[0044] The technical content and features of the present invention are as described above, but the scope of protection of the present invention should not be limited to the content described in the embodiments, but should include various substitutions and modifications that do not depart from the present invention, and are covered by the claims of this patent application.

Claims

1. A method for preparing silver-copper alloy powder, characterized in that: Includes the following steps Step 1: Weigh out polyvinylpyrrolidone K60 and dissolve it in deionized water in the reaction vessel, and add sodium hydroxide to adjust the pH of the solution to 2-6, which will serve as the reaction base solution. Step 2: Weigh out copper nitrate solution and add it dropwise to the reaction vessel. The concentration of the copper nitrate solution is diluted 5-10 times with deionized water, and the concentrations of the glucose solution and L-ascorbic acid solution are diluted 10-30 times with deionized water. Using a peristaltic pump, prepare elemental copper metal powder in two stages: first, add glucose solution for pre-reduction, and then add L-ascorbic acid solution for reduction. The pre-reduction drop rate is 50 mL / min, and the drop time is 30-50% of the total time. The reduction drop rate is 200 mL / min, and the drop time is 50-70% of the total time. The molar ratio of metal ions to glucose solution and L-ascorbic acid solution is 1:0.6-1.

2. Step 3: Add silver nitrate solution dropwise to the reacted solution, while raising the temperature to 70-90℃, and replace the silver ions in the silver nitrate with elemental copper metal powder. Step 4: After the displacement reaction is complete, cool the temperature to 25-30℃ and add L-ascorbic acid solution dropwise to the reaction vessel to reduce the displaced copper ions. The molar ratio of metal ions to L-ascorbic acid solution is 1:0.2-0.

5. Step 5: Wash with deionized water and ethanol respectively, then separate the solid and liquid phases using a centrifuge, and dry in an oven at 45-80 ℃ to obtain silver-copper alloy powder.

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