Method for plating nickel on surface of carbon fiber with high binding force and special activating solution thereof

Abstract

The invention relates to the technical field of composite material surface treatment, in particular to a carbon fiber surface high-binding-force nickel plating method and a special activating solution thereof. The method provided by the invention comprises the following steps: firstly, carrying out desizing and coarsening pretreatment on carbon fibers, then activating by adopting a novel environment-friendly activating solution taking cobalt salt, a coordination agent and a reducing agent as cores, and finally, carrying out chemical nickel plating and optional electroplating thickening. According to the method, an expensive palladium catalyst is completely abandoned, a high-activity catalytic center is generated on the surface of the carbon fiber in situ through the activating solution, and the ultrahigh binding force of a plating layer and a carbon fiber matrix is achieved. The process is simple, environment-friendly and suitable for continuous production, and the prepared nickel-plated carbon fibers perfectly have light weight, high strength and excellent conductive / electromagnetic shielding functions and have wide application prospects in the high-end industrial fields of aerospace, new energy automobiles and the like.

Description

Technical Field

[0001] This invention relates to the field of composite material surface treatment technology, specifically to a method for high-adhesion nickel plating on carbon fiber surfaces and its dedicated activation solution. Background Technology

[0002] Carbon fiber is an ideal reinforcement for preparing high-performance composite materials due to its excellent properties such as high specific strength, high specific modulus, fatigue resistance, and low coefficient of thermal expansion. However, its surface inertness and poor wettability with metal matrices (such as aluminum, magnesium, and copper) make it prone to interfacial reactions that generate brittle phases, resulting in low interfacial bonding strength in composite materials and severely affecting their performance.

[0003] Nickel plating on carbon fiber surfaces is an effective way to solve the above problems. The metallic nickel layer can effectively improve the wettability between carbon fiber and the metal matrix, prevent harmful interfacial reactions, and enhance the interfacial bonding strength and thermal and electrical conductivity of the composite material. Furthermore, nickel-plated carbon fiber itself has broad application prospects in electromagnetic shielding, flexible electrodes, and other fields.

[0004] Currently, nickel plating of carbon fibers mainly adopts chemical plating technology. However, the existing technology has the following common problems: (1) The pretreatment process is complicated: the traditional two-step sensitization-activation method (SnCl2-PdCl2) has a long process, Sn² + (1) Unstable, prone to failure, and Pd is expensive. (2) Poor coating adhesion: Due to the smooth surface of carbon fiber and lack of active sites, the coating has insufficient adhesion to the fiber matrix and is easy to peel off during post-processing or composite process. (3) Poor coating uniformity: The coating is prone to "bridging" between fiber bundles, or the coating thickness on the single filament is uneven, affecting the performance of composite materials. (4) Environmental pollution: Traditional processes contain precious metals and ions that are not easy to clean, resulting in poor environmental performance.

[0005] Therefore, it is of great significance to develop a carbon fiber nickel plating method that is simple in process, low in cost, environmentally friendly, and can obtain a high-bonding and uniform nickel plating layer. Summary of the Invention

[0006] To solve the above-mentioned technical problems, the present invention provides a method for high-adhesion nickel plating on carbon fiber surfaces and a special activation solution thereof.

[0007] The specific technical solution is as follows:

[0008] A method for high-adhesion nickel plating on carbon fiber surfaces specifically includes the following steps:

[0009] (1) Surface pretreatment: The carbon fiber is desized and roughened before treatment to remove the sizing agent on the surface and introduce oxygen-containing functional groups.

[0010] (2) The pretreated carbon fibers are activated using a special activation solution;

[0011] (3) The activated carbon fiber is chemically plated with nickel to obtain nickel-plated carbon fiber.

[0012] The desizing process described in step (1) is as follows: heat-treat the carbon fiber in air at 500-600℃ for 2-5 minutes, or reflux it in concentrated nitric acid at 60-80℃ for 30-60 minutes.

[0013] The roughening process described in step (1) is as follows: the desized carbon fiber is immersed in a mixed acid solution at 70-90℃ for 5-15 minutes to perform slight etching to increase the specific surface area, and then thoroughly washed with deionized water until neutral.

[0014] The mixed acid solution is composed of concentrated nitric acid and concentrated sulfuric acid in a volume ratio of 1:3.

[0015] The activation process described in step (2) is as follows: The carbon fiber treated in step (1) is immersed in a special activation solution and soaked at a constant temperature of 40-60℃ for 10-30 minutes. After taking it out, it is rinsed lightly with water to remove the physically adsorbed ions.

[0016] The composition and concentration of the special activating solution mentioned in step (2) are as follows:

[0017] Cobalt ion source: Cobalt nitrate Co(NO3)2·6H2O 10-30 g / L

[0018] Complexing agent: Sodium citrate 20-50 g / L,

[0019] Reducing agent: Sodium borohydride 0.5-2 g / L

[0020] pH adjuster: ammonia, used to maintain the solution pH between 9.0 and 10.5.

[0021] The solvent is deionized water.

[0022] The electroless nickel plating process described in step (3) is as follows: The activated carbon fiber is immediately transferred into an electroless nickel plating solution with the following components: nickel sulfate: 20-30 g / L, sodium hypophosphite: 25-35 g / L, sodium citrate: 10-20 g / L, sodium acetate: 10-20 g / L, the pH value is adjusted to 8.5-9.5 with ammonia water, the temperature is 75-85℃, and the time is adjusted to 20-60 minutes according to the required coating thickness. Slow mechanical stirring is carried out during the plating process.

[0023] Step (3) is followed by step (4) electroplating to thicken the chemically nickel-plated carbon fiber. The electroplating process is as follows: after rinsing the nickel-plated carbon fiber obtained in step (3), it is quickly transferred to the electroplating tank. After electroplating for 10-30 minutes, it is washed clean and then washed with pure water and dried.

[0024] The electroplating solution used for thickening the plating in step (4) can be a Watt-type nickel plating solution or an aminosulfonate nickel plating solution.

[0025] The nickel-plated carbon fiber is used in the preparation of metal matrix composites or electromagnetic shielding components.

[0026] A special activating solution for a method of high-adhesion nickel plating on carbon fiber surfaces, with the following composition and concentration:

[0027] Cobalt ion source: Cobalt nitrate Co(NO3)2·6H2O 10-30 g / L

[0028] Complexing agent: Sodium citrate 20-50 g / L,

[0029] Reducing agent: Sodium borohydride 0.5-2 g / L

[0030] pH adjuster: ammonia, used to maintain the solution pH between 9.0 and 10.5.

[0031] The solvent is deionized water.

[0032] Compared with the prior art, the present invention has the following beneficial technical effects:

[0033] The specialized activation solution proposed in this invention is free of precious metals, exhibits excellent stability, and effectively introduces high-density, highly active catalytic centers onto the carbon fiber surface. The method proposed in this invention first pre-treats the carbon fiber by desizing and roughening, then activates it using a novel environmentally friendly activation solution based on cobalt salts, a coordinating agent, and a reducing agent. Finally, electroless nickel plating and optional electroplating thickening are performed. This invention completely eliminates the need for expensive palladium catalysts, achieving ultra-high adhesion between the coating and the carbon fiber matrix by generating highly active catalytic centers in situ on the carbon fiber surface through the activation solution. This process is simple, environmentally friendly, and suitable for continuous production. The prepared nickel-plated carbon fiber perfectly combines lightweight, high strength, and excellent electrical conductivity / electromagnetic shielding functions, showing broad application prospects in high-end industrial fields such as aerospace and new energy vehicles.

[0034] The method of the present invention has the following advantages:

[0035] (1) Innovative activation system: Using a non-precious metal cobalt-based activation liquid, highly catalytically active cobalt nanoparticles are generated in situ on the carbon fiber surface through a coordination-reduction co-deposition mechanism, replacing the expensive palladium and significantly reducing costs.

[0036] (2) Ultra-high bonding strength: Through the combination of "heat treatment / acid washing and desizing + mixed acid roughening" pretreatment, the fiber surface is thoroughly cleaned and a micron-nano-level anchoring structure is introduced. At the same time, the surface functional groups are increased, so that the subsequent coating and the substrate can generate strong mechanical interlocking and chemical bonding.

[0037] (3) Uniform and dense coating: The small size and uniform distribution of the cobalt nanoparticles generated by activation ensure uniform nucleation and growth in the initial stage of electroless nickel plating, avoiding coating bridging and nodule formation.

[0038] (4) Environmentally friendly and efficient process: The process is simplified, avoiding tin pollution, reducing the use of precious metals, and better meeting the requirements of green production.

[0039] (5) Excellent product performance: The obtained nickel-plated carbon fiber coating is continuous and complete, with strong bonding force with the fiber. Its reinforced metal matrix composite material exhibits excellent interfacial properties and comprehensive mechanical properties. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the process for high-adhesion nickel plating on carbon fiber surface according to Embodiment 1 of the present invention; Detailed Implementation

[0041] The present invention will now be described in detail with reference to specific embodiments and accompanying drawings, but the scope of protection of the present invention is not limited to the specific embodiments and accompanying drawings.

[0042] Example 1:

[0043] Figure 1 The figure shows a schematic flowchart of the method for high-adhesion nickel plating on the carbon fiber surface according to Embodiment 1 of the present invention. The method for high-adhesion nickel plating on the carbon fiber surface of the present invention specifically includes the following steps:

[0044] (1) Surface pretreatment: The carbon fiber is desized and roughened before treatment to remove the sizing agent on the surface and introduce oxygen-containing functional groups. The desizing process is as follows: The carbon fiber is heat-treated in air at 500°C for 2 minutes, or refluxed in concentrated nitric acid at 60°C for 30 minutes. The roughening process is as follows: The desized carbon fiber is immersed in a mixed acid solution at 70°C for 5 minutes to perform slight etching to increase the specific surface area, and then thoroughly washed with deionized water until neutral. The mixed acid solution is a mixture of concentrated nitric acid and concentrated sulfuric acid in a volume ratio of 1:3.

[0045] (2) The pretreated carbon fibers are activated using a special activation solution. The activation process is as follows: The carbon fibers treated in step (1) are immersed in the special activation solution and soaked at a constant temperature of 40°C for 10 minutes. After being taken out, they are rinsed lightly with water to remove the physically adsorbed ions. The composition and concentration of the special activation solution are as follows:

[0046] Cobalt ion source: Cobalt nitrate Co(NO3)2·6H2O 10g / L

[0047] Complexing agent: Sodium citrate 20g / L,

[0048] Reducing agent: Sodium borohydride 0.5 g / L

[0049] pH adjuster: ammonia, used to maintain the solution pH at 9.0.

[0050] The solvent is deionized water.

[0051] (3) The activated carbon fiber is electroless nickel plating to obtain nickel-plated carbon fiber. The electroless nickel plating process is as follows: The activated carbon fiber is immediately transferred into the electroless nickel plating solution with the following components: nickel sulfate: 20 g / L, sodium hypophosphite: 25 g / L, sodium citrate: 10 g / L, sodium acetate: 10 g / L, the pH value is adjusted to 8.5 with ammonia water, the temperature is 75℃, the time is adjusted to 20 minutes according to the required coating thickness, and slow mechanical stirring is carried out during the plating process.

[0052] (4) Electroplating is performed on the chemically nickel-plated carbon fiber to further increase the coating thickness and performance. Electroplating thickening process: After rinsing the nickel-plated carbon fiber obtained in step (3), it is quickly transferred to the electroplating tank, electroplated for 10 minutes, then rinsed, followed by pure water rinsing and drying. Watt's type nickel plating solution can be used for electroplating thickening.

[0053] The aforementioned nickel-plated carbon fibers are used in the preparation of metal matrix composites or electromagnetic shielding components.

[0054] Example 2:

[0055] The difference from Example 1 is that,

[0056] Step (1) Desizing process: Heat-treat the carbon fiber in air at 550°C for 3 minutes, or reflux it in concentrated nitric acid at 70°C for 50 minutes. The roughening process is as follows: Immerse the desizing carbon fiber in a mixed acid solution at 80°C for 10 minutes;

[0057] Step (2) Activation process: Immerse the carbon fibers treated in step (1) in a special activation solution and soak them at a constant temperature of 50°C for 20 minutes. After removing them, rinse them lightly with water to remove the physically adsorbed ions. The composition and concentration of the special activation solution are as follows:

[0058] Cobalt ion source: Cobalt nitrate Co(NO3)2·6H2O 20g / L

[0059] Complexing agent: Sodium citrate 30g / L,

[0060] Reducing agent: Sodium borohydride 1.0 g / L

[0061] pH adjuster: ammonia, used to maintain the solution pH at 10.0.

[0062] The solvent is deionized water.

[0063] Step (3) Electroless nickel plating process: Immediately transfer the activated carbon fiber into an electroless nickel plating solution with the following components: nickel sulfate: 25 g / L, sodium hypophosphite: 30 g / L, sodium citrate: 15 g / L, sodium acetate: 15 g / L, adjust the pH value to 9.0 with ammonia water, the temperature to 80℃, and adjust the time to 40 minutes according to the required coating thickness. Slow mechanical stirring is carried out during the plating process.

[0064] Step (4) The electroplating solution used for thickening is aminosulfonate nickel plating solution. Electroplating thickening process: After rinsing the nickel-plated carbon fiber obtained in step (3), it is quickly transferred to the electroplating tank, electroplated for 30 minutes, then rinsed, followed by pure water washing and drying.

[0065] Example 3:

[0066] The difference from Example 1 is that,

[0067] Step (1) Desizing process: Heat-treat the carbon fiber in air at 600℃ for 5 minutes, or reflux it in concentrated nitric acid at 80℃ for 60 minutes. The roughening process is as follows: Immerse the desizing carbon fiber in a mixed acid solution at 90℃ for 15 minutes;

[0068] Step (2) Activation process: Immerse the carbon fibers treated in step (1) in a special activation solution and soak them at a constant temperature of 60°C for 30 minutes. After removing them, rinse them lightly with water to remove the physically adsorbed ions. The composition and concentration of the special activation solution are as follows:

[0069] Cobalt ion source: Cobalt nitrate Co(NO3)2·6H2O 30g / L

[0070] Complexing agent: Sodium citrate 50g / L,

[0071] Reducing agent: Sodium borohydride 2g / L

[0072] pH adjuster: ammonia, used to maintain the solution pH at 10.5.

[0073] The solvent is deionized water.

[0074] Step (3) Electroless nickel plating process: Immediately transfer the activated carbon fiber into an electroless nickel plating solution with the following components: nickel sulfate: 30 g / L, sodium hypophosphite: 35 g / L, sodium citrate: 20 g / L, sodium acetate: 20 g / L, adjust the pH value to 9.5 with ammonia water, the temperature to 85℃, and adjust the time to 20-60 minutes according to the required coating thickness. Slow mechanical stirring is carried out during the plating process.

[0075] No step (4).

Claims

1. A method for high-adhesion nickel plating on carbon fiber surfaces, characterized in that, Specifically, the steps include the following: (1) Surface pretreatment: The carbon fiber is desized and roughened before treatment to remove the sizing agent on the surface and introduce oxygen-containing functional groups. (2) The pretreated carbon fibers are activated using a special activation solution; (3) The activated carbon fiber is chemically plated with nickel to obtain nickel-plated carbon fiber.

2. The method for high-adhesion nickel plating on carbon fiber surface according to claim 1, characterized in that: The desizing process described in step (1) is as follows: heat-treat the carbon fiber in air at 500-600℃ for 2-5 minutes, or reflux it in concentrated nitric acid at 60-80℃ for 30-60 minutes.

3. The method for high-adhesion nickel plating on carbon fiber surface according to claim 1, characterized in that: The roughening process described in step (1) is as follows: the desized carbon fiber is immersed in a mixed acid solution at 70-90℃ for 5-15 minutes to perform slight etching to increase the specific surface area, and then thoroughly washed with deionized water until neutral.

4. The method for high-adhesion nickel plating on carbon fiber surface according to claim 3, characterized in that: The mixed acid solution is composed of concentrated nitric acid and concentrated sulfuric acid in a volume ratio of 1:

3.

5. The method for high-adhesion nickel plating on carbon fiber surface according to claim 1, characterized in that: The activation process described in step (2) is as follows: The carbon fiber treated in step (1) is immersed in a special activation solution and soaked at a constant temperature of 40-60℃ for 10-30 minutes. After taking it out, it is rinsed lightly with water to remove the physically adsorbed ions.

6. The method for high-adhesion nickel plating on carbon fiber surface according to claim 5, characterized in that: The composition and concentration of the special activating solution mentioned in step (2) are as follows: Cobalt ion source: Cobalt nitrate Co(NO3)2·6H2O 10-30 g / L Complexing agent: Sodium citrate 20-50 g / L, Reducing agent: Sodium borohydride 0.5-2 g / L pH adjuster: ammonia, used to maintain the solution pH between 9.0 and 10.

5. The solvent is deionized water.

7. The method for high-adhesion nickel plating on carbon fiber surface according to claim 1, characterized in that: The electroless nickel plating process described in step (3) is as follows: The activated carbon fiber is immediately transferred into an electroless nickel plating solution with the following components: nickel sulfate: 20-30 g / L, sodium hypophosphite: 25-35 g / L, sodium citrate: 10-20 g / L, sodium acetate: 10-20 g / L, the pH value is adjusted to 8.5-9.5 with ammonia water, the temperature is 75-85℃, and the time is adjusted to 20-60 minutes according to the required coating thickness. Slow mechanical stirring is carried out during the plating process.

8. The method for high-adhesion nickel plating on carbon fiber surface according to claim 1, characterized in that, Step (3) is followed by: Step (4) electroplating to thicken the chemically nickel-plated carbon fiber. The electroplating process is as follows: after rinsing the nickel-plated carbon fiber obtained in step (3), it is quickly transferred to the electroplating tank. After electroplating for 10-30 minutes, it is washed clean and then washed with pure water and dried. The electroplating solution for thickening can be Watt-type nickel plating solution or aminosulfonate nickel plating solution.

9. The method for high-adhesion nickel plating on carbon fiber surface according to claim 1, characterized in that: The nickel-plated carbon fiber is used in the preparation of metal matrix composites or electromagnetic shielding components.

10. A special activating solution for a method of high-adhesion nickel plating on carbon fiber surfaces, characterized in that, The ingredients and concentrations are as follows: Cobalt ion source: Cobalt nitrate Co(NO3)2·6H2O 10-30 g / L Complexing agent: Sodium citrate 20-50 g / L, Reducing agent: Sodium borohydride 0.5-2 g / L pH adjuster: ammonia, used to maintain the solution pH between 9.0 and 10.

5. The solvent is deionized water.

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