Method for preparing silver powder in specific particle size range by controlling dissolution temperature of silver nitrate

Abstract

The invention discloses a method for preparing silver powder in a specific particle size range by controlling the dissolution temperature of silver nitrate, and belongs to the technical field of metal powder preparation. The preparation method comprises the following steps that a silver nitrate solution with the concentration being 50-200 g / L is prepared, and the prepared silver nitrate dissolving system is heated to the dissolving temperature needed by silver powder within the target particle size range; preparing an ascorbic acid solution with the concentration of 25-150 g / L; slowly adding the silver nitrate solution into the ascorbic acid solution while stirring, wherein the material adding time is 10-20 minutes; in the reaction process, a surfactant is synchronously added, and the addition amount is 1-6 wt.% of Ag < + >; and after the reaction is completed, the silver powder within the target particle size range is separated from the solution, cleaned and dried. According to the method, the particle size of the silver ions reduced into the silver powder is regulated and controlled by accurately controlling the temperature, the particle size controllability is high, the range is wide, the morphology controllability is high, complex additives are not needed, the process is simplified, stability is good, and the method is environmentally friendly and suitable for large-scale production.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal powder preparation, and particularly relates to a method for preparing silver powder with a specific particle size range by controlling the dissolution temperature of silver nitrate. Background Art

[0002] When preparing silver powder with different particle sizes by chemical reduction method, precise control of the silver salt dissolution temperature is crucial for regulating the nucleation and growth processes. Fast nucleation results in smaller particle sizes but may cause agglomeration, while slow reduction is more conducive to the growth of larger particles. The purpose of the present invention is to provide a method for preparing silver powder with a specific particle size range by controlling the dissolution temperature of silver nitrate. By controlling the temperature, the solubility and ionic activity of the silver salt are optimized, the nucleation rate and growth rate are coordinately controlled, and precise regulation of the silver powder particle size and particle morphology is achieved, so as to prepare silver powder within a specific particle size range to meet the special requirements of fields such as electronics, chemical industry, and medicine. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for preparing silver powder with a specific particle size range by controlling the dissolution temperature of silver nitrate.

[0004] The purpose of the present invention is achieved as follows: The method for preparing silver powder with a specific particle size range by controlling the dissolution temperature of silver nitrate includes the following steps: Prepare a silver nitrate solution with a concentration of 50 - 200 g / L, and heat the prepared silver nitrate dissolution system to the dissolution temperature required for silver powder within the target particle size range; Prepare an ascorbic acid solution with a concentration of 25 - 150 g / L; slowly add the silver nitrate solution to the ascorbic acid solution while stirring, and the feeding time is 10 - 20 min; during the reaction, a surfactant is added synchronously, and the addition amount is 1 - 6 wt.% of Ag + ; After the reaction is completed, separate the silver powder within the target particle size range from the solution, wash it, and dry it.

[0005] Compared with the prior art, the technical solution of the present invention has the following advantages: The method of the present invention realizes the preparation of silver powders with different particle size ranges by precisely controlling the dissolution temperature of the silver nitrate dissolution system. In a lower temperature range, the solubility of silver nitrate is moderate. Slowly adding it to the ascorbic acid solution can avoid excessive instantaneous nucleation density, and each single crystal nucleus can obtain more silver ions for growth, enabling the formation of silver powder particles with larger particle sizes. In a higher temperature range, the reduction rate of ascorbic acid increases, resulting in instantaneous high nucleation, and the increase in temperature accelerates the diffusion of silver ions, preventing more silver atoms from directly depositing on the existing crystal nuclei, making it easier to form silver powder particles with smaller particle sizes. The method of the present invention regulates the particle size of silver ions reduced to silver powder by precisely controlling the temperature, with high controllability of particle size, a wide range, strong controllability of morphology, no need for complex additives, simplified process, good stability, environmental friendliness, and suitability for large-scale production. Description of the Drawings

[0006] Figure 1 Particle size test results of the silver powder prepared in Example 1 Figure 2 Particle size test results of the silver powder prepared in Example 2 Figure 3 Particle size test results of the silver powder prepared in Example 3 Detailed Embodiments

[0007] The present invention will be further described below, but it is not limited in any way. Any transformation or replacement based on the teachings of the present invention falls within the protection scope of the present invention.

[0008] The method for preparing silver powders with a specific particle size range by controlling the dissolution temperature of silver nitrate includes the following processes: Prepare a silver nitrate solution with a concentration of 50 - 200 g / L, and heat the prepared silver nitrate dissolution system to the dissolution temperature required for silver powders in the target particle size range; Prepare an ascorbic acid solution with a concentration of 25 - 150 g / L; slowly add the silver nitrate solution to the ascorbic acid solution while stirring, and the feeding time is 10 - 20 min; during the reaction process, a surfactant is added synchronously, and the added amount is 1 - 6 wt.% of Ag + ; After the reaction is completed, separate the silver powders in the target particle size range from the solution, wash, and dry them.

[0009] When the dissolution temperature of the silver nitrate dissolution system is 20 - 30 °C, the particle size range of the silver powder is > 5 μm; when the dissolution temperature is 30 - 40 °C, the particle size range of the silver powder is 3 - 5 μm; when the dissolution temperature is 40 - 50 °C, the particle size range of the silver powder is < 3 μm.

[0010] The control accuracy of the dissolution temperature of the silver nitrate dissolution system is ±1 °C.

[0011] The rate of adding the silver nitrate solution to the ascorbic acid solution is 1-2 mL / min.

[0012] The surfactant is any one of polyvinylpyrrolidone (PVP), polyethylene glycol (PEG), and ethylenediaminetetraacetic acid (EDTA). The molecular weight of the polyvinylpyrrolidone is 10,000-50,000; the molecular weight of the polyethylene glycol is 1,500-4,000.

[0013] The separation is by centrifugation or filtration.

[0014] The washing is with deionized water.

[0015] The temperature of the drying is 40±1°C, and the time is 12-24 h.

[0016] Perform particle size analysis on the dried silver powder, and measure the particle size distribution of the silver powder by a laser particle size analyzer or sieve analysis method.

[0017] Example 1

[0018] —— Preparation of silver powder with a particle size range of >5 μm Prepare a silver nitrate solution with a concentration of 100 g / L, and heat the prepared silver nitrate dissolution system to 25±1°C; Prepare an ascorbic acid solution with a concentration of 100 g / L; while stirring, add the silver nitrate solution to the ascorbic acid solution at a rate of 1 mL / min, and the feeding time is 15 min; during the reaction, simultaneously add polyvinylpyrrolidone (PVP) (molecular weight 20,000), and the addition amount is 3 wt.% of Ag + ; After the reaction is completed, separate the silver powder in the target particle size range from the solution by filtration treatment, remove the impurities in the solution, wash the obtained silver powder with deionized water 3 times to remove the residual impurities or chemical substances on the surface, and dry the washed silver powder at 40±1°C for 18 h to ensure the stability and fluidity of the silver powder during storage.

[0019] Perform particle size analysis on the dried silver powder, and measure the particle size distribution of the silver powder by a laser particle size analyzer. The results are as Figure 1 shown. The particle size D50 of the silver powder is 6.00 μm, meeting the required particle size range.

[0020] Example 2 —— Preparation of silver powder with a particle size range of 3-5 μm Prepare a silver nitrate solution with a concentration of 50 g / L, and heat the prepared silver nitrate dissolution system to 35±1°C; Prepare an ascorbic acid solution with a concentration of 25 g / L; while stirring, add the silver nitrate solution to the ascorbic acid solution at a rate of 1.5 mL / min for 10 min; during the reaction, simultaneously add polyethylene glycol (PEG) (molecular weight 2000), and the addition amount is 6 wt.% of Ag + ; After the reaction is completed, separate the silver powder in the target particle size range from the solution by centrifugation, remove the impurities in the solution, wash the obtained silver powder with deionized water 3 times to remove the residual impurities or chemical substances on the surface, and dry the washed silver powder at 40 ± 1 °C for 12 h to ensure the stability and fluidity of the silver powder during storage.

[0021] Perform particle size analysis on the dried silver powder, and the method is the same as that in Example 1. The results are as Figure 2 shown, and the particle size D50 of the silver powder is 3.70 μm.

[0022] Example 3 —— Preparation of silver powder with a particle size range of < 3 μm Prepare a silver nitrate solution with a concentration of 200 g / L, and heat the prepared silver nitrate dissolution system to 45 ± 1 °C; Prepare an ascorbic acid solution with a concentration of 150 g / L; while stirring, add the silver nitrate solution to the ascorbic acid solution at a rate of 2 mL / min for 20 min; during the reaction, simultaneously add ethylenediaminetetraacetic acid (EDTA), and the addition amount is 1 wt.% of Ag + ; After the reaction is completed, separate the silver powder in the target particle size range from the solution by filtration, remove the impurities in the solution, wash the obtained silver powder with deionized water 3 times to remove the residual impurities or chemical substances on the surface, and dry the washed silver powder at 40 ± 1 °C for 24 h to ensure the stability and fluidity of the silver powder during storage.

[0023] Perform particle size analysis on the dried silver powder, and the method is the same as that in Example 1. The results are as Figure 3 shown, and the particle size D50 of the silver powder is 2.33 μm.

Claims

1. A method for preparing silver powder with a specific particle size range by controlling the dissolution temperature of silver nitrate, characterized in that: Including the following processes: Prepare a silver nitrate solution with a concentration of 50-200 g / L, and heat the prepared silver nitrate solution system to the dissolution temperature required for silver powder in the target particle size range; Prepare an ascorbic acid solution with a concentration of 25-150 g / L; The silver nitrate solution was slowly added to the ascorbic acid solution while stirring, and the addition time was 10-20 min. During the reaction, a surfactant was added simultaneously, and the addition amount was Ag. + 1-6wt.%; After the reaction is completed, the silver powder in the target particle size range is separated from the solution, washed and dried.

2. The preparation method according to claim 1, characterized in that: When the dissolution temperature of the silver nitrate dissolution system is 20-30° C., the particle size range of the silver powder is >5 μm.

3. The preparation method according to claim 1, characterized in that: When the dissolution temperature of the silver nitrate dissolution system is 30-40° C., the particle size range of the silver powder is 3-5 μm.

4. The preparation method according to claim 1, characterized in that: When the dissolution temperature of the silver nitrate dissolution system is 40-50° C., the particle size range of the silver powder is less than 3 μm.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The control accuracy of the dissolution temperature of the silver nitrate dissolution system is ±1°C.

6. The preparation method according to claim 1, characterized in that: The speed of adding the silver nitrate solution to the ascorbic acid solution is 1-2 mL / min.

7. The preparation method according to claim 1, characterized in that: The surfactant is any one of polyvinyl pyrrolidone, polyethylene glycol and ethylenediaminetetraacetic acid.

8. The preparation method according to claim 1, characterized in that: The separation is by centrifugation or filtration.

9. The preparation method according to claim 1, characterized in that: The cleaning is performed with deionized water.

10. The preparation method according to claim 1, characterized in that: The drying temperature is 40±1° C. and the drying time is 12-24 h.

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