A method for preparing micron-sized spherical nickel powder by mixing nickel sources

Abstract

The present invention relates to a method for preparing micron-sized spherical nickel powder by mixing nickel chloride hexahydrate as the main nickel source, assisted by nickel sulfate hexahydrate as a stabilizer, mixed with deionized water according to a molar ratio of (1‑4): 1, put into a water bath for preheating after adding a surfactant, and add sodium hydroxide aqueous solution using a peristaltic pump, then add a reducing agent and carry out heating reaction in a water bath, ultrasonic treatment and cool to room temperature, after the product solid-liquid separation, wash with water, alcohol washing and vacuum drying are respectively carried out to obtain a micron-sized spherical nickel powder with a particle size of 1 μm‑4 μm. The method is by adding nickel sulfate hexahydrate as a stabilizer, and under the premise of ensuring that nickel chloride hexahydrate is the preparation advantage of the main nickel source, not only the nickel ion concentration is enhanced, the yield is improved, and the reaction system is also stabilized, and the problem of unstable reaction rate in the preparation of a traditional single nickel source is effectively solved, and the prepared nickel powder shows significant advantages in particle size, morphology, etc.

Description

Technical Field

[0001] The invention relates to the technical field of nickel powder preparation, in particular to a method for preparing micron-sized spherical nickel powder by mixing nickel sources. Background Art

[0002] Fine nickel powder has great surface effect and volume effect, and shows many special properties in magnetism, internal pressure, thermal resistance, light absorption, chemical activity, etc. As a new material, it has broad application prospects in catalysts, power electrode materials, multilayer ceramic capacitors, conductive fibers, cemented carbide materials, absorption materials, etc., and has become one of the hot spots for the development of new functional materials at home and abroad; in addition, compared with ultrafine nickel powder, fine nickel powder is more conducive to achieving the effect of good coating and uniform coating in the process of preparing silver-coated nickel for conductive slurry technology by chemical plating. However, in the current production process, fine powder has problems such as difficult to control particle size and morphology, too fast reduction rate during the reaction, easy formation of burrs or rough surface on the particle surface, easy agglomeration when adding special reagents to reduce the reaction rate, high technical requirements and high costs, so it is difficult to achieve industrial production.

[0003] In the prior art, a nickel salt is often used as a reaction nickel source, and the reductant selection requires a variety of reductants to be mixed and used, and the operation is relatively complicated. And in the liquid phase reduction system, special reagents are required to provide mild conditions to promote the generation of nickel particle crystals and slowly grow into micron particles, but the standard potential of nickel ions is lower than that of precious metals, and conventional weak reductants cannot be reduced, so it is necessary to use strong reductants such as hydrazine hydrate and potassium borohydride for reduction synthesis, and strong reductants will also increase the reaction rate in the process of promoting nickel ion reduction, resulting in the reaction rate of micron-sized nickel powder particles cannot be controlled, and the phenomenon is severe. Therefore, for the production of micron-sized nickel powder, it is still necessary to have simple operation, a relatively mild reaction process, low equipment requirements and a controllable morphology preparation method. Therefore, it is of great significance to explore the industrial production of micron-sized nickel powder products with high purity, dispersion and uniform particle size distribution and spherical structure. Summary of the invention

[0004] Purpose of the invention: The present invention proposes a method for preparing micron-sized spherical nickel powder by mixing nickel sources, the purpose of which is to solve the problems existing in the prior art.

[0005] Technical solution: The present invention proposes a method for preparing micron-sized spherical nickel powder by mixing nickel sources, using a liquid phase reduction method, without the assistance of a hard template, to prepare micron-sized spherical nickel powder with a particle size of 1 μm-4 μm; the method comprises the following steps:

[0006] Step 1, preparing a mixed nickel source aqueous solution, using nickel chloride hexahydrate as the main nickel source, supplemented with nickel sulfate hexahydrate as a stabilizer, mixing with deionized water at a molar ratio of (1-4):1, and stirring with ultrasonic to dissolve evenly to obtain solution A;

[0007] Step 2: prepare a sodium hydroxide aqueous solution, mix sodium hydroxide and deionized water, stir and dissolve evenly, and obtain solution B;

[0008] Step 3, adding a surfactant to solution A, and subjecting the solution to ultrasonic stirring to mix the solution uniformly, to obtain solution C;

[0009] Step 4: Preheat solution C in a water bath, pump solution B into solution C using a peristaltic pump, and stir evenly to obtain solution D;

[0010] Step 5, adding a reducing agent to solution D, stirring to mix evenly, heating in a water bath for reaction, ultrasonic treatment and cooling to room temperature to obtain product E;

[0011] Step 6: After solid-liquid separation, the product E is washed with water, washed with alcohol and vacuum dried to obtain micron-sized spherical nickel powder.

[0012] Furthermore, the nickel ion concentration of solution A in step 1 is 0.035 mol / L-0.8 mol / L; and the concentration of solution B in step 2 is 0.15-0.95 mol / L.

[0013] Furthermore, in step three, the surfactant is polyvinyl pyrrolidone.

[0014] Furthermore, in the step three, the mass ratio of the added amount of the surfactant to the nickel source is 1:(2.5-2.8).

[0015] Furthermore, in step 4, the preheating temperature of the water bath is 80-90°C.

[0016] Furthermore, in the step 5, the reducing agent is hydrazine hydrate.

[0017] Furthermore, the concentration of the reducing agent in step five is 0.38-1.44 mol / L.

[0018] Furthermore, in step 5, the temperature of the heating reaction is 70-90° C., and the heating reaction time is 2-4 hours.

[0019] Furthermore, the heating reaction in step 5 is carried out in a water bath.

[0020] Furthermore, in step six, the vacuum drying temperature is 60° C., and the vacuum drying time is 12 h.

[0021] Beneficial effects:

[0022] 1. Compared with the prior art, this method prepares micron-sized spherical nickel powder by separately preparing a mixed nickel salt solution and a reducing solution and adopting a peristaltic pump dropwise addition method at normal pressure and a relatively low temperature. It has low equipment requirements, simple operation steps and strong operability.

[0023] 2. Compared with the prior art, this method, while ensuring the preparation advantage of a single nickel source NiCl2·6H2O as the main nickel source, increases the concentration of nickel ions in the nickel source aqueous solution and increases the output by adding a stabilizer NiSO4·6H2O, while assisting NiCl2·6H2O to achieve a stable reaction, thus overcoming the problems of unstable reaction rate and high energy consumption in the prior art of using NiCl2·6H2O as a single nickel source to prepare nickel powder.

[0024] 3. Compared with the prior art, the method, by adding a stabilizer NiSO4·6H2O and mixing the mixed nickel source aqueous solution in the addition ratio of (1-4):1, has significant advantages in nickel powder particle size, nickel powder morphology, etc., solves the problem of uncontrollable reaction in the prior art, and the steps are closely linked, the raw material ratio is properly arranged, and both good performance is maintained and the production efficiency of the reaction product is guaranteed, which meets the needs of large-scale industrial production in the fields of conductive slurries, battery materials, magnetic materials, wave absorbing and special coatings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is the SEM image of the spherical micron nickel powder prepared in Example 1 (*20000);

[0026] Figure 2 This is the SEM image (*4000) of the spherical micron nickel powder prepared in Example 1;

[0027] Figure 3 This is the SEM image of the spherical micron nickel powder prepared in Example 2 (*10000);

[0028] Figure 4 The SEM image of the spherical micron nickel powder prepared in Example 2 (*2000);

[0029] Figure 5 This is the SEM image of the spherical micron nickel powder prepared in Example 3 (*20000);

[0030] Figure 6 This is the SEM image (*4000) of the spherical micron nickel powder prepared in Example 3;

[0031] Figure 7This is the SEM image of the spherical micron nickel powder prepared in Comparative Example 1 (*20000);

[0032] Figure 8 This is the SEM image of the spherical micron nickel powder prepared in Comparative Example 1 (*4000). DETAILED DESCRIPTION

[0033] In order to make the technical means, creative features, objectives and effects of the present invention easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. 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.

[0034] Example 1

[0035] This embodiment adopts a liquid phase reduction method to prepare micron-sized spherical nickel powder with a particle size of 1-3 μm without the assistance of a hard template, comprising the following steps:

[0036] Step 1: Dissolve 0.08 mol NiCl2·6H2O and 0.02 mol NiSO4·6H2O (addition ratio is 4:1) in 125 g deionized water, mix them evenly by ultrasonic, then add 7.5 g PVP and stir them evenly by ultrasonic to obtain solution A; dissolve 0.15 mol NaOH in 125 g deionized water and mix them evenly to obtain solution B;

[0037] Step 2: preheat solution A in a water bath at 80°C, pump solution B into solution A at a pumping speed of 40 ml / min using a peristaltic pump after reaching the preheating temperature, stir with a stirring paddle for 3 h, then add 0.26 mol of 80% hydrazine hydrate and stir evenly, heat at 80°C for 1 h, sonicate for 30 min after the reaction is completed, and cool to room temperature (25°C);

[0038] Step 3: Pour off the supernatant, wash the crude product with water until the conductivity drops below 5 μs / cm, wash it twice with anhydrous ethanol, and dry it in a vacuum drying oven at 60°C for 12 hours to obtain micron-sized spherical nickel powder with a particle size of 1-3 μm.

[0039] Example 2

[0040] This embodiment adopts a liquid phase reduction method to prepare micron-sized spherical nickel powder with a particle size of 1-4 μm without the assistance of a hard template, comprising the following steps:

[0041] Step 1: Dissolve 0.14 mol NiCl2·6H2O and 0.06 mol NiSO4·6H2O (addition ratio is 2.3:1) in 250 g water and mix them evenly by ultrasonic, then add 6.8 g PVP and stir them evenly by ultrasonic to obtain solution A; dissolve 0.12 mol NaOH in 250 g water and mix them evenly to obtain solution B;

[0042] Step 2: preheat solution A in a 90°C water bath, pump solution B into solution A using a peristaltic pump at a pumping speed of 40 ml / min after reaching the preheating temperature, stir with a stirring paddle for 1.5 h, then add 0.28 mol of 80% hydrazine hydrate and stir evenly, heat at 90°C for 3 h, sonicate for 30 min after the reaction is completed, and cool to room temperature (25°C);

[0043] Step 3: Pour off the supernatant, wash the crude product with water until the conductivity drops below 5 μs / cm, wash it twice with anhydrous ethanol, and dry it in a vacuum drying oven at 60°C for 12 hours to obtain micron-sized spherical nickel powder with a particle size of 1-4 μm.

[0044] Example 3

[0045] This embodiment adopts a liquid phase reduction method to prepare micron-sized spherical nickel powder with a particle size of 1.5-2 μm without the assistance of a hard template, comprising the following steps:

[0046] Step 1: Dissolve 0.2 mol NiCl2·6H2O and 0.2 mol NiSO4·6H2O (addition ratio is 1:1) in 500 g water and mix them evenly by ultrasonic, then add 8.8 g PVP and stir them evenly by ultrasonic to obtain solution A; dissolve 0.6 mol NaOH in 500 g water and mix them evenly to obtain solution B;

[0047] Step 2: preheat solution A in a water bath at 80°C, pump solution B into solution A at a pumping speed of 40 ml / min using a peristaltic pump after reaching the preheating temperature, stir for 3 hours using a stirring paddle, then add 0.78 mol of 80% hydrazine hydrate and stir evenly, heat at 90°C for 3 hours, sonicate for 30 minutes after the reaction is completed, and cool to room temperature (25°C);

[0048] Step 3: Pour off the supernatant, wash the crude product with water until the conductivity drops below 5 μs / cm, wash it twice with anhydrous ethanol, and dry it in a vacuum drying oven at 60°C for 12 hours to obtain micron-sized spherical nickel powder with a particle size of 1.5-2 μm.

[0049] Comparative Example 1

[0050] This embodiment adopts a liquid phase reduction method to prepare micron-sized spherical nickel powder with a particle size of 1.5-2 μm without the assistance of a hard template, comprising the following steps:

[0051] Step 1: Dissolve 0.4 mol NiCl2·6H2O in 500 g water and mix evenly by ultrasonic, then add 5 g PVP and stir evenly by ultrasonic to obtain solution A; dissolve 0.3 mol NaOH in 500 g water and mix evenly to obtain solution B;

[0052] Step 2: preheat solution A in a water bath at 80°C, pump solution B into solution A at a pumping speed of 40 ml / min using a peristaltic pump after reaching the preheating temperature, stir the mixture for 3 h using a stirring paddle, then add 0.5 mol of 80% hydrazine hydrate and stir evenly, heat at 90°C for 30 min, react until overflowing, sonicate for 30 min, and cool to room temperature (25°C);

[0053] Step 3: Pour off the supernatant, wash the crude product with water until the conductivity drops below 5 μs / cm, wash it twice with anhydrous ethanol, and dry it in a vacuum drying oven at 60°C for 12 hours to obtain micron-sized spherical nickel powder with a particle size of about 1.5-2 μm.

[0054] The nickel source in Examples 1-3 is NiCl2·6H2O as the main nickel source and NiSO4·6H2O as the stabilizer. The two are mixed in a ratio of (1-4):1 to prepare a mixed nickel source aqueous solution with a nickel ion concentration of 0.8 mol / L. Micron-sized spherical nickel powder is prepared by mixing the nickel source aqueous solution. Figures 1 to 6 It can be seen that the mixed nickel source aqueous solution obtained by adding the stabilizer NiSO4·6H2O and controlling the addition ratio of NiCl2·6H2O to NiSO4·6H2O to be (1-4):1, after adding NiSO4·6H2O during the experiment, compared with the addition of other stabilizers, NiSO4·6H2O not only provides additional Ni 2+ , and in SO4 2- The reaction rate is stable and controllable under the adjustment reaction. At the same time, under the auxiliary stabilization of NiSO4·6H2O, the average particle size of the prepared spherical micron nickel particles is 1-4μm, and they have a complete spherical structure, a smooth particle surface, a controllable particle size, a narrow distribution, high purity and a large specific surface area. Comparative Example 1 is relative to Examples 1-3, and only a single nickel source NiCl2·6H2O is used to prepare a nickel source aqueous solution with a nickel ion concentration of 0.8mol / L. Specifically, no stabilizer is added to the nickel source aqueous solution prepared in Comparative Example 1, resulting in the experimental process relying only on the NiCl2·6H2O aqueous solution, the reaction rate is unstable, and the nickel ion concentration is 0.8mol / L. Figure 7 , Figure 8It can be seen that the prepared spherical micron nickel particles have incomplete spherical structures and are even adhered to each other. The particle surface is not smooth, the particle size is difficult to control, the distribution range is large, the purity is low, and the specific surface area is small.

[0055] In general, the method of the present invention improves the existing method of using NiCl2·6H2O as a single nickel source to prepare nickel powder, which has unstable reaction, uncontrollable nickel powder particle size and nickel powder morphology. The micron-sized spherical nickel powder prepared by adding stabilizer NiSO4·6H2O and the mixed nickel source aqueous solution obtained by adding the ratio of (1-4):1 has significant advantages in nickel powder particle size, nickel powder morphology and the like. By adding stabilizer NiSO4·6H2O, the method not only increases the nickel ion concentration and improves the yield, but also stabilizes the reaction system, effectively solving the problem of unstable reaction rate in the traditional single nickel source preparation, and the steps are closely linked, the raw material ratio is properly arranged, and both good performance is maintained and the production efficiency of the reaction product is guaranteed, which meets the needs of large-scale industrial production.

[0056] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. A method for preparing micron-sized spherical nickel powder by mixing nickel sources, wherein the micron-sized spherical nickel powder is prepared by liquid phase reduction method without the assistance of a hard template, characterized in that: The specific steps of this method are as follows: Step 1: prepare a mixed nickel source aqueous solution, dissolve nickel chloride hexahydrate and nickel sulfate hexahydrate in a molar ratio of (1-4):1 in deionized water, and stir ultrasonically to dissolve them uniformly to obtain a solution A with a nickel ion concentration of 0.035 mol / L-0.8 mol / L; Step 2: prepare a sodium hydroxide aqueous solution, mix sodium hydroxide with deionized water, stir and dissolve evenly, and obtain a solution B with a concentration of 0.15-0.95 mol / L; Step 3, adding a surfactant to solution A, and subjecting the solution to ultrasonic stirring to mix the solution uniformly, to obtain solution C; Step 4: Preheat solution C in a water bath, pump solution B into solution C at a rate of 40 ml / min using a peristaltic pump, and stir evenly to obtain solution D; Step 5, adding hydrazine hydrate to solution D, stirring to mix evenly, heating reaction in a water bath, ultrasonic treatment and cooling to room temperature to obtain product E; in step 5, the concentration of hydrazine hydrate is 0.38-1.44 mol / L, the heating reaction temperature is 70-90° C., and the heating reaction time is 2-4 h; Step 6: After solid-liquid separation, the product E is washed with water, washed with alcohol and vacuum dried to obtain micron-sized spherical nickel powder with a particle size of 1 μm-4 μm, a complete spherical structure and a smooth surface.

2. The method for preparing micron-sized spherical nickel powder by mixing nickel sources according to claim 1, characterized in that: The surfactant in step three is polyvinyl pyrrolidone.

3. The method for preparing micron-sized spherical nickel powder by mixing nickel sources according to claim 1, characterized in that: In the step three, the mass ratio of the added amount of the surfactant to the nickel source is 1:(2.5-2.8).

4. The method for preparing micron-sized spherical nickel powder by mixing nickel sources according to claim 1, characterized in that: The preheating temperature of the water bath in step 4 is 80-90°C.

5. The method for preparing micron-sized spherical nickel powder by mixing nickel sources according to claim 1, characterized in that: The heating reaction in step 5 is carried out by water bath heating reaction.

6. The method for preparing micron-sized spherical nickel powder by mixing nickel sources according to claim 1, characterized in that: The vacuum drying temperature in step 6 is 60° C. and the vacuum drying time is 12 h.

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