Nickle-coated copper micrometer sheet of core-shell structure and preparation method and application thereof

A technology of core-shell structure and nickel-coated copper, which is applied to the core-shell structure of nickel-coated copper micro-sheets. In the field of preparation, it can solve the problems of poor control, few methods, and high nickel content in composite powders, and achieve excellent electrical conductivity and thermal conductivity. Stability, good anti-oxidation effect

Active Publication Date: 2018-09-21

UNIV OF SCI & TECH OF CHINA

7 Cites 3 Cited by

AI-Extracted Technical Summary

Problems solved by technology

[0010] To sum up, the current copper powder nickel plating mainly has the following difficulties: (1) There are few methods for copper microflakes; (2) The nickel content in th...

Method used

Known from above embodiment, the invention provides a kind of nickel-clad copper micro-sheet of core-shell structure and preparation method thereof, nickel-clad copper micro-sheet comprises micron copper sheet and is wrapped in the nickel shell of described micron copper sheet surface ; The aspect ratio of the micron copper sheet is 1:0.9-1.1. The nickel shell maintains the high-aspect-ratio flake-like morphology of the initial micron copper flakes, retains the original high-aspect-ratio flake structure, and the nickel layer is dense and thin, making it have better oxidation properties. Nickel-clad copper microflakes also have excellent electrical conductivity and thermal stability. The preparation method is to mix ethylene glycol and micron copper flakes, then add a reducing agent and nickel salt, and react to obtain nickel-coated copper micron flakes with a core-shell structure; the mass ratio of the copper micron flakes to nickel salt is 7-8:1- 1.1. The present invention uses ethylene glycol as a solvent, which can reduce the diffusion of ions, thereby controlling the kinetics of the reaction, and electrolessly deposits a layer of continuous and dense nickel on the surface of the copper microsheet; due to the self-limiting growth effect, the nickel layer will not The overgrowth, the thickness is well controlled, and the copper sheet has good oxidation resistance under the protection of nickel. The core-shell structure nickel-clad copper microsheets have good application prospects in the preparation of conductive fillers, electromagnetic shielding materials or thermal...

Abstract

The invention provides a nickle-coated copper micrometer sheet of a core-shell structure and a preparation method and application thereof. The method comprises the steps that ethylene glycol and a micrometer copper sheet are mixed, and a reducing agent and nickle salt are added for reaction to obtain the nickle-coated copper micrometer sheet of the core-shell structure, wherein the mass ratio of the micrometer copper sheet to the nickle salt is (7-8) to (1-1).1. According to the method, the ethylene glycol is used as a solvent, and the ethylene glycol can reduce ion diffusion, so that the reaction dynamics are controlled, and a layer of continuous and compact nickle is obtained on the surface of the micrometer copper sheet through electroless deposition; due to a self-limiting growing effect, the nickle layer does not overgrow, the thickness is well controlled, nickle-coated copper still retains the sheet-like morphology with the original high length-width ratio, the original sheet-like structure with the high length-width ratio remains, the nickle-coated copper micrometer sheet of the core-shell structure is obtained, and under protection of nickle, the copper sheet has high oxidation resistance; the nickle layer is compact and thin, so that the nickle-coated copper micrometer sheet has excellent conductivity and thermal stability; the nickle-coated copper micrometer sheet hasgood application prospects in preparation of conductive filler or electromagnetic shielding materials or heat conduction materials.

Application Domain

Transportation and packagingMetal-working apparatus +1

Technology Topic

SolventIon +12

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Examples

Experimental program(2)
Comparison scheme(3)

Example Embodiment

[0045] The present invention provides a method for preparing the core-shell structure nickel-coated copper microplate according to the above technical solution, which includes the following steps:

[0046] Mix ethylene glycol and micron copper flakes, then add reducing agent and nickel salt, and react to obtain core-shell structure nickel-coated copper micro flakes;

[0047] The mass ratio of the copper microflake and the nickel salt is 7-8:1-1.1.

[0048] The preparation method provided by the present invention uses reducing agent, nickel salt and ethylene glycol as the plating solution, and carries out the deposition process on the micron copper sheet under simple heating and stirring, and the process flow is easy to control; the prepared nickel-coated copper micron sheet has a thin nickel coating Continuously dense, with a good core-shell structure; due to the self-limiting growth effect, the nickel layer will not grow excessively and the thickness is well controlled. The nickel-clad copper still maintains the original high aspect ratio flake morphology, resulting in a core-shell structure of nickel-clad copper Micron flakes, and copper flakes have good oxidation resistance under the protection of nickel. The nickel-coated copper microplate has a dense and thin nickel layer, which gives it excellent electrical conductivity and thermal stability. Core-shell structure nickel-coated copper microplates have good application prospects in the preparation of conductive fillers, electromagnetic shielding materials or thermal conductive materials.

[0049] The invention mixes ethylene glycol and micron copper flakes to obtain a dispersion of micron copper flakes. The ethylene glycol is used as a solvent, which can reduce the diffusion of ions, thereby controlling the kinetics of the reaction, and the obtained nickel plating layer is dense and retains the original high aspect ratio sheet structure. The ethylene glycol can submerge the micron copper flakes. In the present invention, the mass ratio of the micron copper flakes to the volume of ethylene glycol is 1 g: (10-15) mL.

[0050] The present invention does not have special restrictions on the source of the copper micron flakes. Commercially available micron copper flakes can be used. The micron copper flakes used in the present invention are purchased from Ningbo Jinlei Nano Material Technology Co., Ltd.

[0051] In the present invention, the micron copper flakes are preferably prepared according to the following method:

[0052] The micron copper flakes to be processed are ultrasonically washed in an acid solution, the supernatant liquid is removed after centrifugation, and the dispersant is added for multiple centrifugation and dispersion to obtain the micron copper flakes.

[0053] The invention removes the organic protective layer and the oxide layer on the surface of the micron copper sheet to be processed through acid solution treatment. In the present invention, the concentration of the acid solution is preferably 0.8-1.2 mol/L, more preferably 1 mol/L; the acid solution at least submerges the micron copper flakes to be processed. The acid solution is preferably selected from one or more of hydrochloric acid solution, sulfuric acid solution and nitric acid solution; more preferably, it is selected from hydrochloric acid solution. After pickling the copper flakes, prevent the copper flakes from contacting air and keep them in the solution.

[0054] In the present invention, the temperature of the ultrasound is preferably 15 to 35°C; the time of the ultrasound is preferably 3 to 6 min, more preferably 4 to 6 min; the working frequency of the ultrasound is preferably 40 kHz; the power of the ultrasound is preferably 300W. In a specific embodiment of the present invention, the ultrasound time is 5 minutes.

[0055] In the specific embodiment of the present invention, the preparation process of the dispersion of micron copper flakes specifically includes:

[0056] Mix the micron copper flakes to be treated with acid solution, ultrasonically wash, and then wash twice with water, discard the upper layer solution, add ethylene glycol and centrifuge, discard the supernatant, add ethylene glycol for dispersion, and obtain micron copper flakes The dispersion.

[0057] In the present invention, the reducing agent is preferably selected from hydrazine hydrate. The nickel salt is preferably selected from one or more of nickel nitrate, nickel acetate and nickel sulfate. The reducing agent is preferably dissolved in ethylene glycol and added to the reaction system in the form of a solution; the nickel salt is preferably dissolved in ethylene glycol and added to the reaction system in the form of a nickel salt solution. In a specific embodiment of the present invention, the nickel salt is nickel nitrate hexahydrate. The mass ratio of the micron copper flakes and the nickel salt is 7-8:1 to 1.1; in a specific embodiment of the present invention, the mass ratio of the micron copper flakes and the nickel salt is 7:1.09.

[0058] In the present invention, the reaction is preferably carried out in a flask well known to those skilled in the art; the temperature of the reaction is preferably 70-90°C, more preferably 75-85°C; the time of the reaction is preferably 50-70 min, more preferably 55 min ~65min. In a specific embodiment of the present invention, the temperature of the reaction is 80°C and the time is 60 min. After the ethylene glycol and the micron copper flakes are mixed, the present invention preferably sequentially adds a reducing agent and a nickel salt to them.

[0059] In the present invention, the reaction further includes:

[0060] The reaction product is removed from the plating solution, and washed with water and ethanol for 2 to 3 times each to obtain a core-shell structured nickel-coated copper microplate.

[0061] In the present invention, drying is preferably carried out after the washing is completed to obtain a core-shell structured nickel-coated copper microplate.

[0062] The preparation method provided by the present invention does not need to add complicated processes and ingredients such as surfactants, dispersants, complexing agents, pH value regulators, etc., and has simple process formula and easy control.

[0063] The present invention provides an application of the core-shell structure nickel-coated copper microplate prepared by the preparation method described in the above technical solution or the application of the core-shell structured nickel-coated copper microplate in the preparation of conductive fillers, electromagnetic shielding materials or thermal conductive materials.

Example Embodiment

[0065] Example 1

[0066] Weigh 7.5g of copper microplates, add 200mL of 1mol/L hydrochloric acid, and ultrasonically wash for 5min to remove the organic protective layer and oxide layer on the surface. Then, after washing twice with water, discard the upper solution and add 100mL of ethylene glycol. Centrifuge, discard the supernatant, add 100mL ethylene glycol to disperse and add to a 500mL flask;

[0067] 5mL 85wt% hydrazine hydrate was added to 100mL ethylene glycol and dissolved, then added to the flask;

[0068] Add 1.09g nickel nitrate hexahydrate to 100mL ethylene glycol, and add the solution to the flask after dissolving;

[0069] Stir and heat at 80°C for 1 hour, then cool down to complete the reaction;

[0070] Pour the upper layer solution, wash twice with water and ethanol, and finally oven dry at 80°C to obtain core-shell structure nickel-coated copper microplates.

[0071] The present invention scans the copper microplates used in Example 1, and the results are as follows figure 1 , figure 1 This is a scanning electron micrograph of the copper microplate used in Example 1 of the present invention; figure 1 It can be seen that the length and width of the copper microplate are both about 40 microns.

[0072] figure 2 This is an enlarged view of the scanning electron micrograph of the copper microplate used in Example 1 of the present invention; figure 2 It can be seen that since the micron copper sheet has not been pretreated, there is a protective layer of organic matter on its surface, and the surface of the copper sheet is relatively smooth.

[0073] image 3 This is a scanning electron micrograph of the oxidized copper microplate in Example 1 of the present invention; it is specifically that after hydrochloric acid is used to wash off the surface protective layer, it will be rapidly oxidized when placed at room temperature. image 3 It is the situation after 3h placed in the air at room temperature.

[0074] Figure 4 It is a scanning electron micrograph at 200 times of the nickel-coated copper microplate prepared in Example 1 of the present invention; Figure 4 You can clearly see the uniform sheet-like structure with high aspect ratio.

[0075] Figure 5 This is a scanning electron micrograph at 1000 times of the nickel-coated copper microplate prepared in Example 1 of the present invention; Figure 5 It can be seen that the flat surface after nickel plating has no dendrites.

[0076] Image 6 This is a scanning electron micrograph at 10,000 times of the nickel-coated copper microplate prepared in Example 1 of the present invention; Image 6 It can be seen that the nickel coating is very dense. Unlike the smooth surface of the initial copper sheet, the surface of the micron sheet has textures. These are the grain boundaries of crystalline nickel, and the thickness of the copper sheet does not increase significantly.

[0077] Figure 7 This is the X-ray powder diffraction pattern (XRD) of the initial copper microplate and nickel-coated copper microplate prepared in Example 1 of the present invention; Figure 7 It can be seen that the peak position has shifted, which proves the formation of nickel plating.

[0078] Figure 8 It is the thermogravimetric curve (TG) and derivative thermogravimetric analysis (DTG) curve diagram of the initial copper microplate in Example 1 of the present invention; Figure 8 It can be seen that the pure copper microplates begin to oxidize at 220°C in dry air. From the peak position of DTG, the oxidation rate reaches the maximum at 280°C.

[0079] Picture 9 It is the thermogravimetric curve (TG) and derivative thermogravimetric analysis (DTG) curve of the nickel-coated copper microplate prepared in Example 1 of the present invention, Picture 9 It can be seen that the nickel-coated copper microplates begin to oxidize at 300°C in dry air. From the peak position of DTG, the oxidation speed reaches the maximum at 385°C, and the high-temperature oxidation resistance in dry air is significantly improved. .

PUM

Property	Measurement	Unit
Concentration	0.8 ~ 1.2	mol/l

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