Nickel-coated graphite powder, additive, electroplating solution and electroplating process thereof

Abstract

The application discloses a kind of nickel-coated graphite powder, additive, electroplating solution and its electroplating process, the additive is particulate matter electroplating nano nickel additive, with complexing agent, current dispersing agent, low potential deposition accelerator and lubricant, the mass ratio of its complexing agent, current dispersing agent, low potential deposition accelerator is 40~100:10:1, in the proportion, electroplating can form a large number of microcrystalline nucleus, but its growth is inhibited, so as to obtain crystalline meticulous nano nickel electroplating layer.The electroplating solution has the additive, and the process parameters are stable during plating process, and the nickel-coated graphite after plating has the advantages of easy water washing, low surface resistance, aging resistance and the like.The electroplating process first uses chemical plating to plate a layer of nickel on the surface of graphite, completely covers the surface of particles, and then electroplates a layer of electroplated nickel on the chemical nickel to obtain nickel-coated graphite powder, which has better surface conductivity, good adhesion, good dispersibility, uniform plating layer and excellent performance as conductive filler.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electroplating, in particular to a nickel-coated graphite powder, an additive, an electroplating solution and an electroplating process thereof. BACKGROUND

[0002] The nickel-coated graphite powder is a coated composite powder material formed by coating a layer of nickel on the surface of graphite core powder by chemical reduction. The nickel-coated graphite powder composite material has both the superior lubricating performance of graphite and the good electrical conductivity and thermal conductivity of metal. It is widely used in electromagnetic shielding, wave absorption, thermal spraying and other fields.

[0003] Most of the existing nickel-coated graphite powders are prepared by hydrogen reduction method, and the process flow is generally as follows: oil removal - water washing - pretreatment - water washing - hydrogen reduction - water washing - drying. This process mainly has the following problems:

[0004] 1. The reaction needs to be carried out at high temperature and high pressure;

[0005] 2. The coating rate is not high, and the surface porosity is high;

[0006] 3. The compactness of the coating is not enough, and the surface resistance is high due to easy oxidation. SUMMARY

[0007] Therefore, the present application provides a nickel-coated graphite powder, an additive, an electroplating solution and an electroplating process thereof. The additive is a particulate electroplating nano-nickel additive, which has a complexing agent, a current dispersing agent, a low-potential deposition promoter and a lubricant. The mass ratio of the complexing agent, the current dispersing agent and the low-potential deposition promoter is 40-100:10:1. In this ratio, a large number of micro-crystal nuclei can be formed during electroplating, but their growth is inhibited, so that a crystalline fine nano-nickel electroplating layer is obtained. The electroplating solution has the additive, and the process parameters are stable during the plating process. The nickel-coated graphite after plating has the advantages of easy water washing, low surface resistance, aging resistance and the like. The electroplating process first uses chemical plating to plate a layer of nickel on the surface of graphite to completely cover the surface of the particles, and then electroplates a layer of crystalline fine electroplated nickel on the chemical nickel to obtain nickel-coated graphite powder. The surface of the nickel-coated graphite powder has better electrical conductivity, good adhesion and good dispersibility, and the plating layer is uniform, so that the nickel-coated graphite powder has excellent performance as a conductive filler.

[0008] The technical scheme adopted by the present application is as follows:

[0009] A nickel-coated graphite powder, wherein the D50 is 80-120 μm, the specific surface area is 0.1-0.2 m2 / g, the powder resistance is less than 0.012 Ω·mm, and the oxidation loss is less than 1.5%.

[0010] An additive, comprising:

[0011] The complexing agent is citric acid or tartaric acid.

[0012] the current dispersing agent is one or more of sodium salt of diphenyl sulfone imide, sodium saccharin;

[0013] the low potential deposition accelerator is one or more of thiourea, ATPN, UPS;

[0014] the wetting agent is one or more of sodium salt of 2-ethylhexyl sulfate, sodium salt of dioctyl sulfosuccinate, sodium dodecyl sulfate;

[0015] The mass ratio of the complexing agent, the current dispersing agent, and the low potential deposition accelerator is 40-100:10:1.

[0016] Based on the same inventive concept, the application further provides an electroplating solution comprising a main solution and the aforementioned additive.

[0017] In the electroplating solution disclosed in the application, the main solution comprises 50-250 g / L of main salt, 20-60 g / L of buffer, and 2-20 g / L of anode activator.

[0018] In the electroplating solution disclosed in the application, the main salt is one or more of nickel sulfamate and nickel sulfate; the buffer is one or more of boric acid, aminoacetic acid, and sodium acetate; and the anode activator is one or more of potassium chloride, nickel chloride, and sodium chloride.

[0019] Based on the same inventive concept, the application further provides an electroplating process using the aforementioned electroplating solution, comprising the following steps:

[0020] Step S1. Chemical plating, mixing graphite particles with a chemical plating nickel solution, stirring and reacting for 30-90 min to obtain chemically plated nickel graphite;

[0021] Step S2. Primary water washing, water washing the chemically plated nickel graphite until the electrical conductivity is less than 20 μS / cm;

[0022] Step S3. Electroplating, mixing the chemically plated nickel graphite with an electroplating solution, using direct current to electroplate for 20-80 h to obtain electroplated graphite;

[0023] Step S4. Secondary water washing, water washing the electroplated graphite until the electrical conductivity is less than 20 μS / cm, and drying to obtain the aforementioned nickel-coated graphite powder.

[0024] In the electroplating process disclosed in the application, in the step S1, the chemical plating nickel solution comprises 150-300 g / L of nickel sulfate, 150-300 g / L of sodium hypophosphite, 50-150 mL / L of ammonia water, and 10-60 g / L of ammonium chloride.

[0025] In the electroplating process disclosed in the application, the temperature in the step S1 is 50-90℃, and the pH is 9-11.

[0026] In the electroplating process disclosed in the application, the particle loading of the electroless plating is 10-40g / L, and the particle loading of the electroplating is 50-100 square meters / L.

[0027] In the electroplating process disclosed in the application, the temperature in the step S3 is 30-60℃, the pH is 2.5-5.5, and the current density is 0.1-5A / square meter.

[0028] The beneficial effects of the application are:

[0029] (1) The additive in the application is a particle electroplating nano nickel additive, which has complexing agent, current dispersing agent, low potential deposition accelerator and lubricant. Each component plays a different role, and the amount consumed in the electroplating process is also different. The application finds that when the mass ratio of the complexing agent, the current dispersing agent and the low potential deposition accelerator is 40-100:10:1, the dispersibility of the graphite powder is good, there is no agglomeration phenomenon, a large number of microcrystalline nuclei can be formed during electroplating, but the growth is inhibited, so that a nano nickel electroplating layer with fine crystallization can be obtained.

[0030] (2) The electroplating solution in the application has a particle electroplating nano nickel additive, which is a nano electroplating solution. The process parameters are stable during plating, and the nickel-coated graphite after plating has the advantages of easy water washing, low surface resistance after drying, aging resistance and the like.

[0031] (3) The electroplating process steps of the application are chemical plating-washing-electroplating-washing-drying. A layer of nickel is first plated on the surface of the graphite particles by chemical plating to completely cover the surface of the particles, further improve the conductivity, facilitate subsequent electroplating, and prevent plating leakage. A layer of electroplated nickel with fine crystallization is then plated on the chemical nickel to make the plating layer uniform, have good adhesion, low porosity, good dispersibility, good aging resistance, low surface resistance and better conductivity. As a conductive filler, it has excellent performance. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0033] Figure 1 is a micrograph of the nickel-coated graphite powder of the application (×500);

[0034] Figure 2A micrograph of nickel-coated graphite powder of the present application (×3000). DETAILED DESCRIPTION

[0035] In the following, only certain exemplary embodiments are simply described. As will be appreciated by those skilled in the art, the described embodiments can be modified in various different ways without departing from the spirit or scope of the present application.

[0036] Reference to“an embodiment” in this application means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase“in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily all directed to the same embodiment, or to a single alternative embodiment. It is explicitly contemplated that embodiments described herein can be combined with each other in various combinations.

[0037] The embodiments of the present application are described in detail below.

[0038] The present application provides an additive, comprising:

[0039] The complexing agent is citric acid or tartaric acid;

[0040] The current dispersing agent is one or more of sodium salt of bis-benzenesulfonimide, sodium saccharin;

[0041] The low-potential deposition accelerator is one or more of thiourea, ATPN (S-carboxyethyl isothiourea hydroxide salt), UPS (3-S-isothiourea sodium propanesulfonate);

[0042] The wetting agent is one or more of 2-ethylhexyl sulfate sodium salt, dioctyl sodium sulfosuccinate, sodium dodecyl sulfate;

[0043] The mass ratio of the complexing agent, the current dispersing agent, and the low-potential deposition accelerator is 40-100:10:1.

[0044] The additive of the present application is a particulate electroplating nanometer nickel additive, which has a complexing agent, a current dispersing agent, a low-potential deposition accelerator, and a lubricant. Each component plays a different role and is consumed in different amounts during the electroplating process. It is found that when the mass ratio of the complexing agent, the current dispersing agent, and the low-potential deposition accelerator is 40-100:10:1, the dispersibility of the graphite micro-powder is good and there is no agglomeration phenomenon. A large number of micro-crystal nuclei can be formed during electroplating, but their growth is inhibited, so that a crystalline fine nanometer nickel electroplating layer can be obtained.

[0045] In the electroplating process, metal ions are transferred to the cathode to form adsorbed atoms, and finally form microcrystalline nuclei. The key steps in the electrodeposition process are the growth of microcrystalline nuclei and the growth of crystals, and the competition of these two steps directly affects the grain state of the plating layer. The particulate electroplating nickel nano additive has high cathode overpotential, high total number of adsorbed atoms, and low atomic adsorption surface mobility, which is a necessary condition for the formation of a large number of microcrystalline nuclei and the inhibition of growth. Due to the inhibition of the growth of the crystal nucleus, a nano nickel electroplating layer is obtained.

[0046] The application also provides an electroplating solution, comprising a main solution and the aforementioned particulate electroplating nickel nano additive.

[0047] The main solution comprises 50-250 g / L of a main salt, 20-60 g / L of a buffer, and 2-20 g / L of an anode activator.

[0048] The main salt is one or more of nickel sulfamate and nickel sulfate; the buffer is one or more of boric acid, aminoacetic acid, and sodium acetate; and the anode activator is one or more of potassium chloride, nickel chloride, and sodium chloride.

[0049] The electroplating solution of the application has a particulate electroplating nickel nano additive, and is a nano electroplating solution. In the plating process, the process parameters are stable, and the nickel-coated graphite obtained after plating has the advantages of easy water washing, low surface resistance after drying, aging resistance, and the like.

[0050] Based on the aforementioned electroplating solution, the application further provides an electroplating process, comprising the following steps:

[0051] Step S1. Chemical plating, mixing graphite particles with a chemical plating nickel solution, stirring and reacting for 30-90 min to obtain chemically plated nickel graphite;

[0052] Step S2. First water washing, water washing the chemically plated nickel graphite until the electrical conductivity is less than 20 μS / cm;

[0053] Step S3. Electroplating, mixing the chemically plated nickel graphite with an electroplating solution, and using direct current to electroplate for 20-80 h to obtain electroplated graphite;

[0054] Step S4. Second water washing, water washing the electroplated graphite until the electrical conductivity is less than 20 μS / cm, and drying to obtain nickel-coated graphite powder.

[0055] The electroplating process of the application comprises the steps of chemical plating, water washing, electroplating, water washing, and drying. A layer of nickel is first plated on the surface of the graphite particles by chemical plating to completely cover the particle surface and further improve the conductivity, which is beneficial to subsequent electroplating and does not cause plating leakage. A layer of crystalline and fine electroplated nickel is then electroplated on the chemical nickel to make the plating layer uniform, have good adhesion, low porosity, good dispersibility, good aging resistance, and low surface resistance, and have better conductivity, thereby having excellent performance as a conductive filler.

[0056] Specifically, in step S1, the electroless nickel plating solution comprises: nickel sulfate 150-300 g / L, sodium hypophosphite 150-300 g / L, ammonia water 50-150 mL / L, and ammonium chloride 10-60 g / L.

[0057] Specifically, in step S1, the reaction temperature is 50-90℃, and the pH is 9-11.

[0058] Specifically, the particle loading of electroless plating is 10-40 g / L, and the particle loading of electroplating is 50-100 square meters / L.

[0059] Specifically, in step S3, the electroplating temperature is 30-60℃, the pH is 2.5-5.5, and the current density is 0.1-5 A / square meter. Example

[0060] An electroless nickel plating solution is prepared according to the formula: nickel sulfate 200 g / L, sodium hypophosphite 200 g / L, ammonia water 100 ml / L, and ammonium chloride 30 g / L.

[0061] Graphite particles (D50=100 μm) are reacted with the electroless nickel plating solution at a temperature of 60℃, a pH of 10, and a loading of 25 g / L for 60 minutes to form a layer of nickel on the surface of the graphite particles, thereby obtaining electroless nickel-plated graphite; and then washed with water to obtain an electrical conductivity of less than 20 μS / cm.

[0062] An electroplating solution is prepared according to the formula: nickel sulfamate 150 g / L, nickel chloride 10 g / L, and boric acid 30 g / L; and a particle electroplating nano-nickel additive: sodium 2-ethylhexyl sulfate 0.5 g / L, citric acid 0.2 g / L, sodium saccharin 0.02 g / L, and ATPN 2 ppm (mass ratio of complexing agent, current dispersant, and low-potential deposition promoter is 100:10:1).

[0063] The electroless nickel-plated graphite is electroplated with the electroplating solution at a temperature of 45℃, a pH of 3, a current density of 2 A / square meter, and a loading of 70 square meters / L for 40 hours using direct current to form a layer of crystalline and fine electroplated nickel on the electroless nickel, and then washed with water to obtain an electrical conductivity of less than 20 μS / cm, dried, and obtained nickel-coated graphite powder.

[0064] See Figure 1 , 2 As shown in FIG. 1, the surface of the nickel-coated graphite powder is crystalline and fine, and the coating is uniform. The D50 of the nickel-coated graphite powder is 100 μm, the specific surface area is 0.1273 m 2 / g, and the powder resistance is less than 0.012 Ω·mm; and the oxidation weight loss of the nickel-coated graphite powder after oxidation in air at 500℃ for 77 minutes is 1.45%. Example

[0065] Prepare the electroless nickel plating solution according to the following formula: 150 g / L nickel sulfate, 150 g / L sodium hypophosphite, 50 ml / L ammonia, and 10 g / L ammonium chloride.

[0066] Graphite particles (D50=100μm) were reacted with electroless nickel plating solution at 50℃, pH 9, and loading amount 10g / L for 30 min with stirring to plate a layer of nickel on the surface of the graphite particles, thus obtaining electroless nickel-plated graphite; then, after washing with water, the conductivity was reduced to less than 20μS / cm.

[0067] The electroplating solution is prepared according to the following formula: nickel aminosulfonate 50g / L, nickel chloride 2g / L, boric acid 20g / L; the nano nickel additive for particulate electroplating is: sodium dioctyl sulfosuccinate 0.1g / L, salicylic acid 0.2g / L, sodium bis(benzenesulfonyl)imide 0.02g / L, UPS 2ppm (the mass ratio of complexing agent, current dispersant, and low potential deposition promoter is 100:10:1).

[0068] Electroless nickel-plated graphite was electroplated with an electroplating solution at 30℃, pH 2.5, current density 5A / m², and loading capacity 50 m² / L using direct current for 20 hours. A finely crystalline layer of electroplated nickel was then electroplated onto the electroless nickel plating. The mixture was then washed with water until the conductivity was less than 20 μS / cm, and dried to obtain nickel-coated graphite powder. The D50 of the nickel-coated graphite powder was determined to be 80 μm, and its specific surface area was 0.1417 m². 2 / g, powder resistivity less than 0.012Ω·mm; nickel-coated graphite powder oxidized in air at 500℃ for 77min, the weight loss was 1.43%. Example

[0069] Prepare the electroless nickel plating solution according to the following formula: 300 g / L nickel sulfate, 300 g / L sodium hypophosphite, 150 ml / L ammonia, and 60 g / L ammonium chloride.

[0070] Graphite particles (D50=100μm) were reacted with electroless nickel plating solution at 90℃, pH 11, and loading amount 40g / L for 90min with stirring to plate a layer of nickel on the surface of the graphite particles, thus obtaining electroless nickel-plated graphite; then, after washing with water, the conductivity was reduced to less than 20μS / cm.

[0071] The electroplating solution is prepared according to the following formula: nickel aminosulfonate 250 g / L, nickel chloride 20 g / L, boric acid 60 g / L; the nano nickel additive for particulate electroplating is: sodium 2-ethylhexyl sulfate 1 g / L, citric acid 0.2 g / L, sodium saccharin 0.02 g / L, ATPN 2 ppm (the mass ratio of complexing agent, current dispersant, and low potential deposition promoter is 100:10:1).

[0072] Electroless nickel-plated graphite was electroplated with an electroplating solution at 60℃, pH 5.5, current density 0.1 A / m², loading 100 m² / L, using direct current, for 80 h. A finely crystalline layer of electroplated nickel was then electroplated onto the electroless nickel plating. The mixture was then washed with water until the conductivity was less than 20 μS / cm, and dried to obtain nickel-coated graphite powder. The D50 of the nickel-coated graphite powder was determined to be 120 μm, and its specific surface area was 0.1346 m². 2 / g, powder resistivity less than 0.012Ω·mm; nickel-coated graphite powder oxidized in air at 500℃ for 77min, the weight loss was 1.41%. Example

[0073] The mass ratio of complexing agent, current dispersant, and low potential deposition promoter in the particulate electroplating nano nickel additive was changed to 80:10:1, and the rest was the same as in Example 1. Example

[0074] The mass ratio of complexing agent, current dispersant, and low potential deposition promoter in the particulate electroplating nano nickel additive was changed to 60:10:1, and the rest was the same as in Example 1. Example

[0075] The mass ratio of complexing agent, current dispersant, and low potential deposition promoter in the particulate electroplating nano nickel additive was changed to 40:10:1, and the rest was the same as in Example 1. Example

[0076] The mass ratio of complexing agent, current dispersant, and low potential deposition promoter in the particulate electroplating nano nickel additive was changed to 20:10:1, and the rest was the same as in Example 1.

[0077] Table 1 shows the dispersibility and agglomeration of nano-nickel additives with different proportions of particulate matter during electroplating. When the ratio of complexing agent, current dispersant, and low potential deposition promoter is 40~100:10:1, the dispersibility is good and there is no agglomeration.

[0078] Table 1. Effects of different proportions of particulate matter in nano-nickel plating additives

[0079]

[0080] The above are merely preferred embodiments of the present invention and are 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. An additive, characterized in that, The additive, used in the electroplating step of nickel-coated graphite powder, consists of the following components: The chelating agent is citric acid or salicylic acid; The current dispersant is one or more of sodium bis(benzenesulfonyl)imide and sodium saccharin. The low potential deposition promoter is one or more of thiourea, ATPN, and UPS; The wetting agent is one or more of sodium 2-ethylhexyl sulfate and sodium dioctyl sulfosuccinate; The mass ratio of the complexing agent, current dispersant, and low potential deposition promoter is 60~100:10:

1.

2. An electroplating solution, characterized in that, It includes the main solution and the additive as described in claim 1.

3. The electroplating solution according to claim 2, characterized in that, The main solution comprises 50-250 g / L of main salt, 20-60 g / L of buffer, and 2-20 g / L of anodic activator.

4. The electroplating solution according to claim 3, characterized in that: The main salt is one or more of nickel aminosulfonate and nickel sulfate; The buffer is one or more of boric acid, aminoacetic acid, and sodium acetate; The anodic activator is one or more of potassium chloride, nickel chloride, and sodium chloride.

5. An electroplating process using the electroplating solution according to any one of claims 2 to 3, characterized in that, Includes the following steps: Step S1. Chemical plating: Mix graphite particles with chemical nickel plating solution and stir for 30-90 minutes to obtain chemically nickel-plated graphite. Step S2. Rinse once with water until the conductivity of the electroless nickel plating ink is less than 20 μS / cm; Step S3. Electroplating: Mix the electroless nickel-plated graphite with the electroplating solution, and electroplat for 20-80 hours using direct current to obtain electroplated graphite. Step S4. Second water washing: Wash the electroplated graphite ink until the conductivity is less than 20 μS / cm, then dry to obtain nickel-coated graphite powder. The nickel-coated graphite powder has a D50 of 80~120 and a specific surface area of ​​0.1~0.2 m². 2 / g, powder resistivity less than 0.012Ω·mm, oxidation weight loss less than 1.5%.

6. The electroplating process according to claim 5, characterized in that, In step S1, the electroless nickel plating solution includes: nickel sulfate 150~300g / L, sodium hypophosphite 150~300g / L, ammonia water 50~150mL / L, and ammonium chloride 10~60g / L.

7. The electroplating process according to claim 5, characterized in that, In step S1, the reaction temperature is 50~90℃ and the pH is 9~11.

8. The electroplating process according to claim 5, characterized in that, The particle loading for electroless plating is 10~40 g / L, and the particle loading for electroplating is 50~100 m² / L.

9. The electroplating process according to claim 5, characterized in that, In step S3, the electroplating temperature is 30~60℃, the pH is 2.5~5.5, and the current is 0.1~5A / square meter.

10. A nickel-coated graphite powder prepared by the electroplating process described in any one of claims 5 to 9.

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