Surface copper plating method for graphite powder
By using an alkanolamine-based auxiliary complexing agent to adjust the pH value during the chemical copper plating process, the problem of uneven copper particle plating on the graphite powder surface was solved, achieving a small-particle-size and uniform copper particle plating effect.
Patent Information
- Application Number
- CN202511537037.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-27
- Publication Date
- 2026-01-30
AI Technical Summary
Existing technologies struggle to deposit small and uniform copper particles onto the surface of graphite powder with a particle size of 5-10 μm, especially under alkaline conditions where the pH of the plating solution is unstable, leading to uneven copper particle distribution.
Alkylamine auxiliary complexing agents such as ethylenediamine, triethanolamine, diethanolamine, triethylenetetramine, and diethylenetriamine are used in conjunction with the main complexing agent to adjust and maintain the pH value of the plating solution. Copper particles smaller than 200 nm are then deposited on the surface of graphite powder by chemical copper plating.
It was achieved that copper particles with a particle size of less than 200 nm and uniform particle size were deposited on the surface of graphite powder, which improved the stability of the plating solution and the uniform deposition effect of copper particles.
Smart Images
Figure CN121428540A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of chemical plating solution, in particular to a method for plating copper on the surface of graphite powder. BACKGROUND
[0002] Graphite / Cu composite material has good electrical conductivity, thermal conductivity, lubricity and mechanical strength, and is widely used in the fields of spraying material, liquid metallurgical material, self-lubricating bearing and battery negative material. However, due to poor wettability between graphite and copper, poor interface bonding and uneven plating layer, the application of graphite / Cu composite material is limited to a certain extent.
[0003] At present, the methods for preparing copper-coated graphite powder mainly include electroplating copper and chemical plating copper. However, the copper-coated graphite powder prepared by electroplating copper has problems such as graphite powder agglomeration, cathode surface caking and low current efficiency, so that the electroplating copper method is gradually abandoned by technicians.
[0004] Compared with the electroplating copper method, the chemical plating copper method has simple equipment and easy operation, and is more suitable for surface modification of non-continuous phase.
[0005] The existing technology for chemical plating copper on the surface of graphite powder is usually graphite powder with a size of dozens of microns. For example, 50-75um graphite powder is usually used as the substrate for chemical plating copper on the surface of graphite powder. However, there is no public disclosure of chemical plating copper on the surface of graphite powder with a smaller particle size of 5-10um and a larger specific surface area of 1.5m 2 / g. The main reason is that the graphite powder with a smaller particle size and a larger specific surface area has high surface energy and strong adsorption capacity for gas molecules, which seriously interferes with the plating process. The plating reaction is difficult to proceed at a low temperature, and the reaction speed will increase when the reaction temperature is increased, so that the pH of the plating solution is rapidly reduced. When the pH value is reduced to below 9, the reaction stops. It is necessary to continuously add sodium hydroxide to adjust the pH value. However, the unstable pH value of the plating solution will lead to uneven size of the copper particles plated on the surface of the graphite powder, and the reaction process is not easy to control. As far as the present applicant knows, this technical problem has not been properly solved so far. SUMMARY
[0006] The technical problem to be solved by the present application is to provide a method for plating copper on the surface of graphite powder, which can plate a layer of copper particles with a relatively small particle size of less than 200nm and a relatively uniform particle size on the surface of graphite powder with a particle size of 5-10um.
[0007] The technical solution of the present application is to provide a method for plating copper on the surface of graphite powder, which comprises pre-treating the graphite powder before plating, and chemically plating copper on the pre-treated graphite powder. The chemical plating of copper comprises the following steps:
[0008] (1) Weigh one of copper sulfate pentahydrate, copper chloride and copper nitrate, add deionized water to prepare a solution with a concentration of 30-50 g / L, and then add the main complexing agent, alcohol amine auxiliary complexing agent, pH adjuster and pH stabilizer to adjust the pH value of the above solution to 9-12.
[0009] (2) Pour the above-prepared plating solution into the reaction tank, set the reaction temperature to 50-80℃, add the pretreated 5-10μm graphite powder, and stir and disperse for 5-30 minutes.
[0010] (3) Add 30-100g / L of copper plating reducing agent, keep it at the temperature for 10-60 minutes and then take it out;
[0011] The main complexing agent is one of ammonium citrate, sodium ethylenediaminetetraacetate, potassium sodium tartrate, sodium citrate, and sodium acetate, and the concentration of the main complexing agent is 30-50 g / L.
[0012] The alkanolamine-based auxiliary complexing agent is one of ethylenediamine, triethanolamine, diethanolamine, triethylenetetramine, and diethylenetriamine, and the concentration of the alkanolamine-based auxiliary complexing agent is 5-20 g / L;
[0013] The pH stabilizer is one of anhydrous sodium carbonate, sodium bicarbonate and potassium carbonate, and the concentration of the pH stabilizer is 20-60 g / L.
[0014] The pH adjuster is a 20%-30% sodium hydroxide solution or potassium hydroxide solution.
[0015] The copper plating method for graphite powder of this invention has the following advantages: The 5-10μm graphite powder of this invention has a relatively large specific surface area compared to graphite powders with larger particle sizes in the prior art, making coating more difficult. However, this invention introduces an alkanolamine-based auxiliary complexing agent, such as one of ethylenediamine, triethanolamine, diethanolamine, triethylenetetramine, and diethylenetriamine, in conjunction with the main complexing agent. The alkanolamine-based auxiliary complexing agent itself can complex with copper ions, reducing the free concentration of copper ions, improving the stability of the plating solution, enhancing the complexing effect of the main complexing agent, and overcoming the problem of insufficient complexation by a single main complexing agent under specific pH conditions. In addition, since the electroless copper plating solution reacts under alkaline conditions, the pH value of the plating solution will drop rapidly as the reaction proceeds, which will affect the reaction rate. However, the weak alkalinity of the alkaline auxiliary complexing agent can adjust the pH of the plating solution and maintain the stability of the pH value through acid-base neutralization reaction, thereby ensuring that copper ions can be deposited uniformly. Therefore, the copper plating method for graphite powder of the present invention can deposit a layer of copper particles with a relatively small particle size, such as less than 200 nm, and relatively uniform particle size on the surface of graphite powder with a particle size of 5-10 μm.
[0016] Furthermore, the mass fraction of 5-10μm graphite powder in the solution before the addition of the copper plating reducing agent is 2%-5%. Using this mass fraction further ensures the aforementioned technical effects.
[0017] Further, the pretreated graphite powder is subjected to chemical copper plating, including: weighing copper sulfate pentahydrate, dissolving it in deionized water to prepare a copper sulfate solution with a concentration of 50 g / L; adding ammonium citrate with a concentration of 50 g / L, ethylenediamine with a concentration of 20 g / L, and anhydrous sodium carbonate with a concentration of 60 g / L to the copper sulfate solution; adjusting the pH of the solution to 12 using 30% sodium hydroxide solution; introducing the above-prepared plating solution into a reaction vessel; setting the reaction temperature to 60℃; adding the pretreated 5-10 μm graphite powder; stirring and dispersing for 5-30 min; then adding 100 g / L formaldehyde solution; maintaining the temperature for 30 min before removing the solution. In the copper plating method for graphite powder of the present invention, after adopting the above-mentioned preferred technical solution, the ethylenediamine in the amine-based auxiliary complexing agent, in combination with the ammonium citrate in the main complexing agent, further reduces the free concentration of copper ions, further improves the stability of the plating solution, further enhances the complexing effect of the main complexing agent, and further overcomes the problem of insufficient complexing by a single main complexing agent under specific pH conditions. The weak alkalinity of the ethylenediamine in the amine-based auxiliary complexing agent can further adjust the pH of the plating solution, making the pH value more stable, and further ensuring that copper ions can be deposited uniformly. This preferred technical solution further ensures that a layer of copper particles with a relatively small particle size, such as less than 200 nm, and relatively uniform particle size is deposited on the surface of graphite powder with a particle size of 5-10 μm. Attached Figure Description
[0018] Figure 1 This is an electron microscope image of the surface copper plating method using the graphite powder of the present invention after copper plating in Example 1.
[0019] Figure 2 This is an electron microscope image of the surface copper plating method using the graphite powder of the present invention, as described in Example 2.
[0020] Figure 3 This is an electron microscope image of copper plating after copper plating using the copper plating method of the graphite powder of the present invention in Example 3.
[0021] Figure 4 These are electron microscope images of the copper-plated comparative examples.
[0022] Figure 5 This is an EDS analysis diagram of Example 1 of the copper plating method for graphite powder of the present invention. Detailed Implementation
[0023] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. It should be noted that these descriptions of specific embodiments are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various specific embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.
[0024] The method for copper plating on the surface of graphite powder in this invention requires pretreatment of the graphite powder before copper plating on a 5-10μm graphite powder surface. This pretreatment includes degreasing, roughening, sensitization, activation, cleaning, and drying before chemical copper plating. The specific steps are as follows:
[0025] Step (1) Surface degreasing of 5-10μm graphite powder: Prepare a sodium hydroxide solution with a concentration of 20-50g / L. Weigh 5-10μm graphite powder with a sodium hydroxide solution mass fraction of 5%-10%, such as 0.6-1kg of graphite powder, and add it to the sodium hydroxide solution. Ultrasonically stir at 300-500rpm (r / min) for 20-60min, then allow it to settle. Remove the sodium hydroxide solution and wash the precipitate with deionized water until the pH value of the water is 7-9. The above stirring can also be described as: ultrasonically stirring for 30min followed by settling, with a stirring speed of 300rpm (r / min).
[0026] Step (2) Acid washing and roughening of 5-10μm graphite powder after degreasing: Add the 5-10μm graphite powder after degreasing and cleaning in step (1) to a sulfuric acid solution with a concentration of 100-300g / L, ultrasonically stir at 300-500rpm for 20-60min, and then let it settle. Remove the sulfuric acid solution and wash the precipitate with deionized water until the pH value of the water is 5-7.
[0027] Step (3) Sensitize the roughened graphite powder: Weigh stannous oxide, add hydrochloric acid to dissolve the stannous oxide, then dilute with water to prepare a stannous oxide sensitizing solution with a concentration of 5-50 g / L; add the 5-10 μm graphite powder roughened in Step (2) to the sensitizing solution, ultrasonically stir at 300-500 rpm for 20-60 min, and then let it settle to remove the stannous oxide sensitizing solution. Wash the precipitate with deionized water until the stannous oxide sensitizing solution on the surface of the graphite powder is cleaned.
[0028] Step (4) Activate the sensitized graphite powder: Weigh silver nitrate, dissolve it in water, add ammonia water, and prepare a silver ammonia activation solution with a concentration of 5-20 g / L. Add the 5-10 μm graphite powder sensitized in step (3) to the activation solution, stir ultrasonically at 500-800 rpm for 10-60 min, and then let it settle. Remove the silver ammonia activation solution, wash the precipitate twice with deionized water, wash it once with alcohol, and then dry it.
[0029] Step (5) involves chemically plating copper onto the activated and dried graphite powder. The chemical copper plating includes the following steps:
[0030] (1) Weigh one of copper sulfate pentahydrate, copper chloride and copper nitrate, add deionized water to prepare a solution with a concentration of 30-50 g / L, and then add the main complexing agent, alcohol amine auxiliary complexing agent, pH adjuster and pH stabilizer to adjust the pH value of the solution to 9-12; it can be understood that the pH value of the solution is adjusted after all the above substances have dissolved.
[0031] (2) Pour the above-prepared plating solution into the reaction tank and turn on the reaction tank heating system. Set the reaction temperature to 50-80℃, add the pretreated 5-10μm graphite powder, and stir and disperse for 5-30 minutes. The mass fraction of the graphite powder in the above plating solution is 2%-5%, or 0.6-1kg of graphite powder.
[0032] (3) Add 30-100g / L of copper plating reducing agent, keep it at the temperature for 10-60 minutes and then take it out;
[0033] The main complexing agent is one of ammonium citrate, sodium ethylenediaminetetraacetate, potassium sodium tartrate, sodium citrate, and sodium acetate, and the concentration of the main complexing agent is 30-50 g / L.
[0034] The alkanolamine-based auxiliary complexing agent is one of ethylenediamine, triethanolamine, diethanolamine, triethylenetetramine, and diethylenetriamine, and the concentration of the alkanolamine-based auxiliary complexing agent is 5-20 g / L;
[0035] The pH stabilizer is one of anhydrous sodium carbonate, sodium bicarbonate and potassium carbonate, and the concentration of the pH stabilizer is 20-60 g / L.
[0036] The pH adjuster is a 20%-30% sodium hydroxide solution or potassium hydroxide solution;
[0037] The copper plating reducing agent is one of formaldehyde solution, sodium hypophosphite, and sodium borohydride.
[0038] The electroless copper plating also includes the steps of settling, cleaning, drying, and testing the graphite powder taken out in step "(3)". Since the settling, cleaning, drying, and testing described here are routine operations for those skilled in the art, they will not be described in detail here.
[0039] Example 1
[0040] Step (1) Surface degreasing of 5-10μm graphite powder: Prepare 20L of sodium hydroxide solution with a concentration of 50g / L, weigh 1kg of 5-10μm graphite powder, add it to the sodium hydroxide solution, ultrasonically stir for 30min and then settle, stirring speed 300rpm (i.e. r / min), remove sodium hydroxide solution, wait for complete settling, pour off the supernatant, wash the precipitate, i.e. the remaining graphite powder, with deionized water 5 times until the pH value of the deionized water is 7.
[0041] Step (2) Acid washing and roughening of 5-10μm graphite powder after degreasing: Add 5-10μm graphite powder after degreasing and cleaning in step (1) to 10L of sulfuric acid solution with a concentration of 100g / L, stir ultrasonically for 30min and then settle. Stir at 300rpm to remove sulfuric acid solution. After complete settling, pour off the supernatant and wash the precipitate, i.e. the remaining graphite powder, with deionized water 3 times until the pH value of the deionized water is 6.
[0042] Step (3) Sensitize the roughened graphite powder: Weigh 0.2 kg of stannous oxide, add 0.4 L of hydrochloric acid to dissolve the stannous oxide, then dilute with water to prepare 20 L of stannous oxide sensitizing solution with a concentration of 10 g / L; Add the 5-10 μm graphite powder roughened in step (2) to the stannous oxide sensitizing solution, stir ultrasonically for 30 min and let it settle, stirring at 300 rpm to remove the stannous oxide sensitizing solution, that is, after complete settling, pour off the supernatant, and wash the precipitate, i.e. the remaining graphite powder, with deionized water twice until the stannous oxide sensitizing solution on the surface of the graphite powder is cleaned.
[0043] Step (4) Activate the sensitized graphite powder: Weigh 0.05 kg of silver nitrate, dissolve it in water, add ammonia water, and prepare 10 L of silver ammonia activation solution with a concentration of 5 g / L. Add the 5-10 μm graphite powder sensitized in step (3) to the activation solution, stir ultrasonically for 30 min and let it settle. Stir at 500 rpm and remove the silver ammonia activation solution. After complete settling, pour off the supernatant. Wash the precipitate, i.e. the remaining graphite powder, with deionized water twice and alcohol once, and then dry it.
[0044] Step (5) involves chemically plating copper onto the pretreated graphite powder: Weigh 1 kg of copper sulfate pentahydrate and add it to the mixing tank. Add 20 L of deionized water to dissolve and prepare a copper sulfate solution with a concentration of 50 g / L. Add 1 kg of ammonium citrate, 0.2 kg of ethylenediamine, and 0.6 kg of anhydrous sodium carbonate to the copper sulfate solution. Adjust the pH of the solution to 12 using 30% sodium hydroxide solution. This can be called copper plating step (1). Pour the prepared plating solution into the reaction tank, turn on the heating system of the reaction tank, and set the reaction temperature to 60°C. Add the 5-10 μm graphite powder that has been sensitized and dried in step (4). The graphite powder is still 1 kg added in step (1). Stir and disperse for 30 min. This can be called copper plating step (2). Add 2 kg of formaldehyde solution, keep warm and react for 30 min, and then remove the solution. This can be called copper plating step (3). Then settle, clean, dry, and test. Since the sedimentation, cleaning, drying, and testing described herein are routine operations for those skilled in the art, they will not be elaborated upon here or in the following specific embodiments (this sentence indicates that they will not be repeated in the following embodiments). The copper plating steps (1), (2), and (3) described above are the same as those in Embodiments 2, 3, and the comparative embodiment, and will not be repeated in the following embodiments.
[0045] Example 2
[0046] Step (1) Surface degreasing of 5-10μm graphite powder: Prepare 20L of sodium hydroxide solution with a concentration of 50g / L, weigh 1kg of 5-10μm graphite powder, add it to the sodium hydroxide solution, ultrasonically stir for 60min and then settle, stirring at 500rpm, remove the sodium hydroxide solution, that is, after complete settling, pour off the supernatant, wash the precipitate, that is, the remaining graphite powder, with deionized water 4 times until the pH value of the deionized water is 8.
[0047] Step (2) Acid washing and roughening of 5-10μm graphite powder after degreasing: Add 5-10μm graphite powder after degreasing and cleaning in step (1) to 10L of sulfuric acid solution with a concentration of 100g / L, stir ultrasonically for 30min and then settle. Stir at 300rpm to remove sulfuric acid solution. After complete settling, pour off the supernatant and wash the precipitate, i.e. the remaining graphite powder, with deionized water 5 times until the pH value of the deionized water is 7.
[0048] Step (3) Sensitize the roughened graphite powder: Weigh 1 kg of stannous oxide, add 1 L of hydrochloric acid to dissolve the stannous oxide, then dilute with water to prepare 20 L of stannous oxide sensitizing solution with a concentration of 50 g / L; Add the 5-10 μm graphite powder roughened in step (2) to the stannous oxide sensitizing solution, stir ultrasonically for 20 min and let it settle, stir at 500 rpm to remove the stannous oxide sensitizing solution, that is, after complete settling, pour off the supernatant, and wash the precipitate, i.e. the remaining graphite powder, with deionized water twice until the stannous oxide sensitizing solution on the surface of the graphite powder is cleaned.
[0049] Step (4) Activate the sensitized graphite powder: Weigh 0.1 kg of silver nitrate, dissolve it in water, add ammonia water, and prepare 10 L of silver ammonia activation solution with a concentration of 10 g / L. Add the 5-10 μm graphite powder sensitized in step (3) to the activation solution, stir ultrasonically for 60 min and let it settle. Stir at 800 rpm and remove the silver ammonia activation solution. After complete settling, pour off the supernatant. Wash the precipitate, i.e. the remaining graphite powder, with deionized water twice and alcohol once, and then dry it.
[0050] Step (5) involves chemically plating copper onto the pretreated graphite powder: Weigh 0.8 kg of copper chloride and add it to the mixing tank. Add 20 L of deionized water to dissolve and prepare a copper chloride solution with a concentration of 40 g / L. Add 0.8 kg of disodium ethylenediaminetetraacetate, 0.2 kg of triethanolamine, and 0.6 kg of sodium bicarbonate to the copper chloride solution. Adjust the pH of the solution to 10 using a 25% potassium hydroxide solution. Pour the prepared plating solution into the reaction tank, turn on the heating system of the reaction tank, and set the reaction temperature to 70 °C. Add the 5-10 μm graphite powder that has been sensitized and dried in step (4). The amount of graphite powder is still 1 kg added in step (1). Stir and disperse for 20 min, then add 2 kg of sodium hypophosphite. Keep the reaction at the temperature for 30 min and then remove the powder. Then, allow it to settle, clean, dry, and test.
[0051] Example 3
[0052] Step (1) Surface degreasing of 5-10μm graphite powder: Prepare 20L of sodium hydroxide solution with a concentration of 50g / L, weigh 1kg of 5-10μm graphite powder, add it to the sodium hydroxide solution, ultrasonically stir for 30min and let it settle, stirring at 300rpm, remove the sodium hydroxide solution, that is, after complete settling, pour off the supernatant, wash the precipitate, that is, the remaining graphite powder, with deionized water 5 times until the pH value of the deionized water is 7.
[0053] Step (2) Acid washing and roughening of 5-10μm graphite powder after degreasing: Add 5-10μm graphite powder after degreasing and cleaning in step (1) to 10L of sulfuric acid solution with a concentration of 100g / L, stir ultrasonically for 30min and then settle. Stir at 300rpm to remove sulfuric acid solution. After complete settling, pour off the supernatant and wash the precipitate, i.e. the remaining graphite powder, with deionized water 5 times until the pH value of the deionized water is 7.
[0054] Step (3) Sensitize the roughened graphite powder: Weigh 0.4 kg of stannous oxide, add 0.8 L of hydrochloric acid to dissolve the stannous oxide, then dilute with water to prepare 20 L of stannous oxide sensitizing solution with a concentration of 20 g / L; Add the 5-10 μm graphite powder roughened in step (2) to the stannous oxide sensitizing solution, stir ultrasonically for 60 min and let it settle, stirring at 300 rpm to remove the stannous oxide sensitizing solution, that is, after complete settling, pour off the supernatant, and wash the precipitate, i.e. the remaining graphite powder, with deionized water twice until the stannous oxide sensitizing solution on the surface of the graphite powder is cleaned.
[0055] Step (4) Activate the sensitized graphite powder: Weigh 0.2 kg of silver nitrate, dissolve it in water, add ammonia water, and prepare 10 L of silver ammonia activation solution with a concentration of 2 g / L. Add the 5-10 μm graphite powder sensitized in step (3) to the activation solution, stir ultrasonically for 30 min and let it settle. Stir at 500 rpm and remove the silver ammonia activation solution. After complete settling, pour off the supernatant. Wash the precipitate, i.e. the remaining graphite powder, with deionized water twice and alcohol once, and then dry it.
[0056] Step (5) involves chemically plating copper onto the pretreated, activated, and dried graphite powder: Weigh 0.6 kg of copper nitrate and add it to a mixing tank. Add 20 L of deionized water to dissolve and prepare a copper nitrate solution with a concentration of 30 g / L. Add 0.6 kg of potassium sodium tartrate, 0.1 kg of triethylenetetramine, and 0.4 kg of potassium carbonate to the copper nitrate solution. Adjust the pH of the solution to 9 using 30% sodium hydroxide solution. Pour the prepared plating solution into a reaction tank, turn on the heating system of the reaction tank, and set the reaction temperature to 80 °C. Add the 5-10 μm graphite powder that has been sensitized and dried in step (4). The amount of graphite powder is still 1 kg added in step (1). Stir and disperse for 5 min, then add 1 kg of formaldehyde solution. Keep the reaction at the temperature for 60 min and then remove the powder. Then, allow it to settle, clean, dry, and test.
[0057] Comparative Examples
[0058] Step (1) Surface degreasing of 5-10 μm graphite powder: Prepare 20 L of sodium hydroxide solution with a concentration of 20 g / L, weigh 1 kg of graphite powder, add it to the sodium hydroxide solution, ultrasonically stir for 30 min and let it settle, stirring at 300 rpm, remove the sodium hydroxide solution, that is, after complete settling, pour off the supernatant, wash the precipitate, that is, the remaining graphite powder, with deionized water 4 times until the pH value of the deionized water is 7.
[0059] Step (2) Acid washing and roughening of 5-10 μm graphite powder after degreasing: Add the graphite powder after degreasing and cleaning in step (1) to 10 L of sulfuric acid solution with a concentration of 100 g / L, stir ultrasonically for 30 min and then settle. Stir at 300 rpm to remove the sulfuric acid solution. After complete settling, pour off the supernatant and wash the precipitate, i.e. the remaining graphite powder, with deionized water 3 times until the pH value of the deionized water is 6.
[0060] Step (3) Sensitize the roughened 5-10µm graphite powder: Weigh 0.2kg stannous oxide, add 0.4L hydrochloric acid to dissolve the stannous oxide, then dilute with water to prepare 20L of stannous oxide sensitizing solution with a concentration of 10g / L; Add the roughened graphite powder from step (2) to the stannous oxide sensitizing solution, ultrasonically stir for 30min and then settle, stirring at 300rpm to remove the stannous oxide sensitizing solution, that is, after complete settling, pour off the supernatant, and wash the precipitate, i.e. the remaining graphite powder, with deionized water twice until the stannous oxide sensitizing solution on the surface of the graphite powder is cleaned.
[0061] Step (4) Activate the sensitized 5-10 μm graphite powder: Weigh 0.05 kg of silver nitrate, dissolve it in water, add ammonia water, and prepare 10 L of silver ammonia activation solution with a concentration of 5 g / L. Add the sensitized graphite powder from step (3) to the activation solution, stir ultrasonically for 30 min and let it settle. Stir at 500 rpm and remove the silver ammonia activation solution. After complete settling, pour off the supernatant. Wash the precipitate, i.e. the remaining graphite powder, twice with deionized water and once with alcohol, and then dry it.
[0062] Step (5) involves chemically plating copper onto the pretreated (activated and dried) 5-10µm graphite powder: Weigh 1kg of copper sulfate pentahydrate and add it to the mixing tank. Add 20L of deionized water to dissolve and prepare a copper sulfate solution with a concentration of 50g / L. Add 1kg of ammonium citrate and 0.6kg of anhydrous sodium carbonate to the copper sulfate solution. Adjust the pH of the solution to 12 using 30% sodium hydroxide solution. Pour the prepared plating solution into the reaction tank, turn on the heating system of the reaction tank, and set the reaction temperature to 60℃. Add the pretreated (sensitized and dried) graphite powder from step (4), stir and disperse for 30min, then add 2kg of formaldehyde solution. Keep the reaction at this temperature for 30min and then remove the powder. Then, allow it to settle, clean, dry, and test.
[0063] from Figures 1-3 As can be seen from the SEM images, the copper plating method for graphite powder using this invention can deposit a layer of copper particles with relatively small particle sizes, such as less than 200 nm, onto the surface of graphite powder with a particle size of 5-10 μm. Figure 4 As can be seen, the copper particles plated in the comparative examples are relatively large, typically between 200 nm and 1 μm, and the uniformity of particle size is also relatively poor. Compared with the comparative examples without alkanolamine-based auxiliary complexing agents, the copper particles plated by the surface copper plating method of the graphite powder of the present invention are smaller and more uniform in size.
[0064] EDS analysis of the sample from Example 1 showed that... Figure 5 As shown in the EDS results, the particles plated on the surface are confirmed to be copper particles, with a copper plating amount of 9.47%, as shown in the table below:
[0065] Element wt% C 90.53 Cu 9.47 Total amount 100
[0066] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A method for copper plating the surface of graphite powder, comprising pre-treatment of the graphite powder before plating, characterized in that: The pretreated graphite powder is subjected to electroless copper plating, which comprises the following steps: (1) one of copper sulfate pentahydrate, copper chloride and copper nitrate is weighed, dissolved in deionized water to prepare a solution with a concentration of 30-50 g / L, and then a main complexing agent, an alcohol amine auxiliary complexing agent, a pH regulator and a pH stabilizer are added to the solution to adjust the pH value of the above solution to 9-12; (2) the prepared plating solution is introduced into a reaction tank, the reaction temperature is set to 50-80℃, and the pretreated 5-10 μm graphite powder is added, and stirred and dispersed for 5-30 min; (3) 30-100 g / L of copper plating reducing agent is added, and after 10-60 min of heat preservation reaction, it is taken out; The main complexing agent is one of ammonium citrate, sodium ethylenediaminetetraacetate, potassium sodium tartrate, sodium citrate and sodium acetate, and the concentration of the main complexing agent is 30-50 g / L. The alcohol amine auxiliary complexing agent is one of ethylenediamine, triethanolamine, diethanolamine, triethylenetetramine and diethylenetriamine, and the concentration of the alcohol amine auxiliary complexing agent is 5-20 g / L. The pH stabilizer is one of anhydrous sodium carbonate, sodium bicarbonate and potassium carbonate, and the concentration of the pH stabilizer is 20-60 g / L. The pH regulator is a 20%-30% sodium hydroxide solution or a potassium hydroxide solution.
2. The method of claim 1, wherein: The mass fraction of 5-10 μm graphite powder in the solution before adding the copper plating reducing agent is 2%-5%.
3. The method of claim 1, wherein the copper plating is performed by electroplating. The pretreated graphite powder is subjected to electroless copper plating, which comprises: weighing copper sulfate pentahydrate, dissolving in deionized water to prepare a copper sulfate solution with a concentration of 50 g / L; adding 50 g / L of ammonium citrate, 20 g / L of ethylenediamine and 60 g / L of anhydrous sodium carbonate to the copper sulfate solution, adjusting the pH value of the solution to 12 with a 30% sodium hydroxide solution, introducing the prepared plating solution into a reaction tank, setting the reaction temperature to 60℃, adding pretreated 5-10 μm graphite powder, stirring and dispersing for 5-30 min, adding 100 g / L of formaldehyde solution, and taking out after 30 min of heat preservation reaction.