Graphene and carbon nano tube doped silver plating electroplating solution and preparation method thereof

Abstract

The invention belongs to the technical field of silver plating, and particularly relates to a graphene and carbon nano tube doped silver plating electroplating solution and a preparation method thereof.The graphene and carbon nano tube doped silver plating electroplating solution comprises 20-50 g / L of silver cyanide, 80-150 g / L of potassium cyanide, 15-30 g / L of potassium carbonate, 70-90 g / L of graphene and carbon nano tube composite powder, 5-12 g / L of electroplating additive and the balance water; wherein the graphene and carbon nanotube composite powder comprises 40-65% of graphene and carbon nanotubes in a ratio of 1: 1-1.5: 1, 15-25% of a dispersant and the balance of an organic solvent, and the electroplating additive comprises 20-35% of a surfactant, 8-17% of a dispersant, 5-10% of a stabilizer and the balance of water. The graphene and carbon nano tube doped silver plating electroplating solution provided by the invention has an obvious enhancement effect on the wear resistance, the conductivity and the hardness of a silver plating layer.

Description

Technical Field

[0001] The invention belongs to the technical field of silver plating, and in particular relates to a graphene and carbon nanotube doped silver plating solution and a preparation method thereof. Background Art

[0002] Silver plating is the process of metal cations depositing on the surface of the plated part. The silver plating solution directly affects the appearance of the final plated part. With the development of science and technology, the requirements for the conductivity, wear resistance and hardness of the plated parts are getting higher and higher, especially in the aerospace and communication terminal industries. The demand for such products is increasing.

[0003] At present, the main silver plating solutions are ordinary cyanide silver plating and cyanide-free silver plating. However, with the changes in market demand, it is difficult to obtain products with better conductivity, stronger wear resistance and higher hardness by ordinary silver plating solutions. Theoretical studies have shown that adding an appropriate amount of suitable carbon elements to the plating solution can enhance the thermal conductivity and conductivity of the coating, and can also greatly improve the lubrication between the coating and other contact surfaces, thereby improving the wear resistance of the coating. At present, the commonly used carbon element materials in various studies are graphite, graphene, and carbon nanotubes. Among them, graphite has excellent friction reduction and self-lubricating effects, but due to its internal crystal structure and chemical bonding mode, the conductivity and mechanical strength of the silver coating obtained after adding it to the silver plating solution will be greatly reduced; in contrast, graphene is a single-layer honeycomb two-dimensional material, and its own electrical conductivity, thermal conductivity and mechanical properties are very excellent. The hollow tubular structure of carbon nanotubes also provides itself with good electrical conductivity, thermal conductivity and mechanical properties. The coating obtained by mixing these two into the silver plating solution will have better electrical conductivity, thermal conductivity and wear resistance. However, due to the unique hollow structure of carbon nanotubes, adding carbon nanotubes alone to the silver plating solution for electroplating will result in poor bonding of the resulting coating. When encountering a high temperature, high humidity, and high acid and alkali environment during subsequent product transportation and processing, it is easy to cause peeling, oxidation and other adverse phenomena, ultimately affecting product quality and performance.

[0004] Based on this situation, the present invention proposes a preparation method and application of a graphene and carbon nanotube doped silver plating solution. Summary of the invention

[0005] The purpose of the present invention is to provide a graphene and carbon nanotube doped silver plating solution and a preparation method thereof, aiming to solve the technical problem in the prior art that the conductivity, wear resistance and hardness of products made from the existing silver plating solution need to be improved.

[0006] To achieve the above-mentioned purpose, the graphene and carbon nanotube doped silver plating electroplating solution provided in the embodiment of the present invention comprises 20-50 g / L of silver cyanide, 80-150 g / L of potassium cyanide, 15-30 g / L of potassium carbonate, 70-90 g / L of graphene and carbon nanotube composite powder, 5-12 g / L of electroplating additives and the balance of water; wherein the graphene and carbon nanotube composite powder comprises 40-65% of the graphene and carbon nanotubes in a ratio of 1:1-1.5:1, 15-25% of a dispersant and the balance of an organic solvent, and the electroplating additive comprises 20-35% of a surfactant, 8-17% of a dispersant, 5-10% of a stabilizer and the balance of water.

[0007] As a further solution of the present invention, the graphene is a single-layer graphene with a purity of more than 98%.

[0008] As a further solution of the present invention, the carbon nanotubes are multi-walled carbon nanotubes with a diameter of 50-100 nm and a length of 1-200 μm.

[0009] As a further embodiment of the present invention, the dispersant is one or more mixtures of polyvinyl alcohol (PVA) or polyacrylate (TPO) or triethylhexyl phosphoric acid (TP).

[0010] As a further embodiment of the present invention, the organic solvent is one of N,N-dimethylformamide (DMF), tetrahydrofuran (THF) or ethyl acetate (EA).

[0011] As a further embodiment of the present invention, the surfactant is a mixture of one or more of polyethylene glycol-400 (PEG) or Triton X-114 (TX) or nonylphenol polyoxyethylene ether (OP).

[0012] As a further embodiment of the present invention, the stabilizer is one or more mixtures of glycerol (GL) or carboxymethyl cellulose (CMC) or sodium stearate (SS).

[0013] As a further solution of the present invention, the water in the electroplating additive is deionized water, distilled water or double distilled water.

[0014] As the same inventive concept of the present invention, the present application also provides a method for preparing a graphene and carbon nanotube doped silver plating solution, comprising the following steps: 1. Preparation of graphene and carbon nanotube composite powder: S1: Weigh 40-65% of graphene and carbon nanotubes in a ratio of 1:1-1.5:1 and put them into a stirrer, add 15-25% of a dispersant and the remainder of an organic solvent, and stir for 4-6 hours to dissolve the solids to obtain a mixture A; S2: Spread the mixture A obtained in S1 on a tray, put it into an oven and bake it at 70-80° C. for 2-3 hours, and completely dry it to obtain the graphene and carbon nanotube composite powder; (II) Preparation of electroplating additives: S3: Add 20-35% of surfactant to 20% of water and stir to obtain mixture B; S4: add 8-17% of dispersant and 5-10% of stabilizer to the mixture B in S3, control the temperature to 30-50°C, and stir for 1 hour to obtain a mixture C; S5: Add the remaining amount of water to the mixture B in S4, maintain the temperature and stir for 2-3 hours to obtain an electroplating additive; (III) Preparation of graphene and carbon nanotube doped silver plating solution: S6: Add 2 / 3 volume of pure water into the electroplating tank; S7: Add 80-150g / L potassium cyanide to the pure water in S6, heat to 40 degrees and stir to dissolve; S8: Add 20-50 g / L silver cyanide to the potassium cyanide solution obtained in S6 and dissolve to obtain a mixture D; S9: adding 15-30 g / L potassium carbonate to the mixture D obtained in S7 to dissolve and obtain a mixture E; S10: adding 70-90 g / L of graphene and carbon nanotube composite powder and 5-12 g / L of electroplating additive to the mixture E obtained in S9, stirring and dissolving to obtain a mixture F; S11: Add the remaining amount of water to a standard volume of 200 L, and cool the temperature to 16-25° C. to obtain the required graphene and carbon nanotube doped silver plating solution.

[0015] The above one or more technical solutions in the graphene and carbon nanotube doped silver plating solution provided by the embodiment of the present invention have at least one of the following technical effects: First, the graphene and carbon nanotube doped silver plating solution prepared by the technical solution of the present invention, most particularly, contains graphene and carbon nanotube composite powder, which has a significant enhancement effect on the wear resistance, conductivity and hardness of the silver coating. Since graphene is a two-dimensional structure and carbon nanotubes are a three-dimensional structure, both have a very large specific surface area. After the graphene and carbon nanotube composite powders are doped into the silver plating solution, the dispersion, uniformity and interfacial bonding force of silver ions on the surface of the substrate can be greatly increased. In addition, due to the special physical and chemical properties of graphene and carbon nanotubes, in addition to improving the antioxidant capacity of the silver coating, the wear resistance, conductivity and hardness of the silver coating can also be greatly increased. The final product will have better performance than the product obtained by the ordinary silver plating process and can better meet the special needs of customers.

[0016] Second, the electroplating additive prepared by the technical solution of the present invention contains dispersants and stabilizers, which are all common organic or inorganic substances on the market, have excellent stability themselves, and are all non-toxic and harmless substances. When added to the silver plating solution, in addition to increasing the dispersibility of the graphene and carbon nanotube composite powder in the silver plating solution, it can also increase the dispersibility and stability of various components in the silver plating solution, so that the silver layer on the surface of the final product is deposited more evenly and smoothly.

[0017] Third, the graphene and carbon nanotube doped silver plating solution prepared by the technical method of the present invention has a faster silver ion deposition rate, a wider range of operable current density, and a more stable pH value of the plating solution. Compared with products prepared by the traditional cyanide silver plating system, the silver-plated products prepared using the silver plating solution have stronger silver layer adhesion, smoother surface, better wear resistance, better conductivity, and higher hardness, and the overall quality of the silver-plated products is improved.

[0018] Fourth, the products plated with the graphene and carbon nanotube doped silver plating solution (YCYY-35) prepared by the technical solution of the present invention and the commercially available traditional silver plating solutions X, Y, and Z, all use their optimal process parameters to plate a silver layer on the surface of the same workpiece. After the electroplating is completed, the conductivity, wear resistance and hardness of the coating implemented by the graphene and carbon nanotube doped silver plating solution prepared by the technical solution of the present invention and the coating implemented by the traditional silver plating solution are greatly improved.

[0019] Fifth, the graphene and carbon nanotube doped silver plating solution prepared by the technical solution of the present invention has a simple preparation process, can be used for silver plating on the surface of substrates of various shapes, specifications and sizes, and has a simple and convenient use method and a wide range of applications. In addition, the production process and use process do not require high temperatures, and the production and use energy consumption is low, and it is easy to achieve large-scale production and application, with excellent economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0021] Figure 1 The graphene and carbon nanotube doped silver plating solution prepared according to the technical solution of the present invention and the common silver plating solutions X, Y, and Z on the market are used in Example 1, and the plating parameters are controlled to remain consistent. The scanning electron microscope (SEM) microscopic images of the products after plating on the workpiece surface are compared, from left to right and from top to bottom are X, Y, Z, YCYY-35.

[0022] Figure 2 The graphene and carbon nanotube doped silver plating solution prepared according to the technical solution of the present invention and the common silver plating solutions X, Y, and Z on the market in Example 1 are used, and the plating parameters are controlled to remain consistent. The hardness test indentation diagrams of the products after plating on the workpiece surface are compared, from left to right and from top to bottom are X, Y, Z, YCYY-35.

[0023] Figure 3 The wear resistance test traces of the products after plating on the workpiece surface using the graphene and carbon nanotube doped silver plating solution prepared according to the technical solution of the present invention and the common silver plating solutions X, Y, and Z on the market in Example 1, and controlling the plating parameters to remain consistent, are compared. From left to right and from top to bottom, they are X, Y, Z, YCYY-35.

[0024] Figure 4 The graphene and carbon nanotube doped silver plating solution (YCYY-35) prepared by the technical solution of the present invention and the products plated by the commercially available traditional silver plating solutions X, Y, and Z are respectively plated with a silver layer on the surface of the same workpiece using their optimal process parameters. After the electroplating is completed, the conductivity (contact resistance), wear resistance (wear cycle), and hardness (Vickers hardness) of the coating are tested, and a comparison table of some preferred results is provided. DETAILED DESCRIPTION

[0025] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the embodiments of the present invention, and should not be construed as limiting the present invention.

[0026] In the description of the embodiments of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0027] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0028] In the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances. Example

[0029] In one embodiment of the present invention, a graphene and carbon nanotube doped silver plating solution is provided, comprising 20-50 g / L of silver cyanide, 80-150 g / L of potassium cyanide, 15-30 g / L of potassium carbonate, 70-90 g / L of graphene and carbon nanotube composite powder, 5-12 g / L of electroplating additives and the balance of water; wherein the graphene and carbon nanotube composite powder comprises 40-65% of graphene and carbon nanotubes in a ratio of 1:1-1.5:1, 15-25% of a dispersant and the balance of an organic solvent, and the electroplating additive comprises 20-35% of a surfactant, 8-17% of a dispersant, 5-10% of a stabilizer and the balance of water.

[0030] In another embodiment of the present invention, the graphene is a single-layer graphene with a purity of more than 98%.

[0031] In another embodiment of the present invention, the carbon nanotubes are multi-walled carbon nanotubes with a diameter of 50-100 nm and a length of 1-200 μm.

[0032] In another embodiment of the present invention, the dispersant is polyvinyl alcohol (PVA) or polyacrylate (TPO) or a mixture of triethylhexylphosphonic acid (TP).

[0033] In another embodiment of the present invention, the organic solvent is one of N,N-dimethylformamide (DMF) or tetrahydrofuran (THF) or ethyl acetate (EA).

[0034] In another embodiment of the present invention, the surfactant is a mixture of one or more of polyethylene glycol-400 (PEG) or Triton X-114 (TX) or nonylphenol polyoxyethylene ether (OP).

[0035] In another embodiment of the present invention, the stabilizer is one or more mixtures of glycerol (GL) or carboxymethyl cellulose (CMC) or sodium stearate (SS).

[0036] In another embodiment of the present invention, the water in the electroplating additive is deionized water, distilled water or double distilled water.

[0037] In the embodiment of the present invention, the preparation process of the graphene and carbon nanotube doped silver plating solution is as follows: 1. Preparation of graphene and carbon nanotube composite powder: S1: Weigh 40% of graphene and carbon nanotubes in a ratio of 1:1 and put them into a stirrer, add 15% of PVA and 45% of DMF, and stir for 4 hours to dissolve the solids to obtain a mixture A; S2: Spread the mixture A obtained in S1 on a tray, put it in an oven and bake it at 70° C. for 2 hours, and completely dry it to obtain a graphene and carbon nanotube composite powder; (II) Preparation of electroplating additives: S3: Add 20% PEG to 20% water and stir to obtain mixture B; S4: Add 8% PVA and 5% GL to the mixture B in S3, control the temperature to 30°C, and stir for 1 hour to obtain a mixture C; S5: Add 47% of water to the mixture B in S4 and stir at the maintained temperature for 2 hours to obtain the electroplating additive.

[0038] (III) Preparation of graphene and carbon nanotube doped silver plating solution: S6: Add 2 / 3 volume of pure water into the electroplating tank; S7: Add 80-150g / L potassium cyanide to the pure water in S6, heat to 40 degrees and stir to dissolve; S8: Add 20-50 g / L silver cyanide to the potassium cyanide solution obtained in S6 and dissolve to obtain a mixture D; S9: adding 15-30 g / L potassium carbonate to the mixture D obtained in S7 to dissolve and obtain a mixture E; S10: adding 70-90 g / L of graphene and carbon nanotube composite powder and 5-12 g / L of electroplating additive to the mixture E obtained in S9, stirring and dissolving to obtain a mixture F; S11: adding the remaining amount of water to a standard volume of 200 L, and cooling the solution to 16-25° C. to obtain the desired graphene and carbon nanotube doped silver plating solution; The graphene and carbon nanotube doped silver plating solution prepared by the present invention is used to plate a silver layer on the surface of a pre-plated part. The process parameters to be controlled during the electroplating process are as follows: pH is 12-14, the use temperature is 16-25°C, the silver ion content in the bath is 20-50g / L, the graphene and carbon nanotube composite powder content is 70-90g / L, and the plating solution does not need to be filtered during use. 15g of graphene and carbon nanotube composite powder can be added for every 2kg of silver plated. After the electroplating is completed, the conductivity (contact resistance), wear cycle, and Vickers hardness test results of the product are 0.2mΩ, 2000 cycles, and 228.5HV, respectively.

[0039] Example 2: The preparation process of the graphene and carbon nanotube doped silver plating solution provided by the present invention is as follows: 1. Preparation of graphene and carbon nanotube composite powder: S1: Weigh 45% of graphene and carbon nanotubes in a ratio of 1.1:1 and put them into a stirrer, add 17% of TPO and 38% of DMF, and stir for 4 hours to dissolve the solids to obtain a mixture A; S2: Spread the mixture A obtained in S1 on a tray, put it in an oven and bake it at 70° C. for 2 hours, and completely dry it to obtain a graphene and carbon nanotube composite powder; (II) Preparation of electroplating additives: S3: Add 23% TX to 20% water and stir to obtain mixture B; S4: Add 10% TPO and 6% CMC to the mixture B in S3, control the temperature to 35°C, and stir for 1 hour to obtain a mixture C; S5: Add 41% of water to the mixture B in S4 and stir at the maintained temperature for 2 hours to obtain the electroplating additive.

[0040] (III) Preparation of graphene and carbon nanotube doped silver plating solution: S6: Add 2 / 3 volume of pure water into the electroplating tank; S7: Add 80-150g / L potassium cyanide to the pure water in S6, heat to 40 degrees and stir to dissolve; S8: Add 20-50 g / L silver cyanide to the potassium cyanide solution obtained in S6 and dissolve to obtain a mixture D; S9: adding 15-30 g / L potassium carbonate to the mixture D obtained in S7 to dissolve and obtain a mixture E; S10: adding 70-90 g / L of graphene and carbon nanotube composite powder and 5-12 g / L of electroplating additive to the mixture E obtained in S9, stirring and dissolving to obtain a mixture F; S11: adding the remaining amount of water to a standard volume of 200 L, and cooling the solution to 16-25° C. to obtain the desired graphene and carbon nanotube doped silver plating solution; The graphene and carbon nanotube doped silver plating solution prepared by the present invention is used to plate a silver layer on the surface of a pre-plated part. The process parameters to be controlled during the electroplating process are as follows: pH is 12-14, the use temperature is 16-25°C, the silver ion content in the bath is 20-50g / L, the graphene and carbon nanotube composite powder content is 70-90g / L, and the plating solution does not need to be filtered during use. 15g of graphene and carbon nanotube composite powder can be added for every 2kg of silver plated. After the electroplating is completed, the conductivity (contact resistance), wear cycle, and Vickers hardness test results of the product are 0.25mΩ, 2100 cycles, and 254.2HV, respectively.

[0041] Example 3: The preparation process of the graphene and carbon nanotube doped silver plating solution provided by the present invention is as follows: 1. Preparation of graphene and carbon nanotube composite powder: S1: Weigh 50% of graphene and carbon nanotubes in a ratio of 1.2:1 and put them into a stirrer, add 19% of TP and 31% of THF, and stir for 5 hours to dissolve the solids to obtain a mixture A; S2: Spread the mixture A obtained in S1 on a tray, put it in an oven and bake it at 75°C for 2.5 hours, and completely dry it to obtain the graphene and carbon nanotube composite powder; (II) Preparation of electroplating additives: S3: Add 26% OP to 20% water and stir to obtain mixture B; S4: Add 12% TP and 7% SS to the mixture B in S3, control the temperature to 40°C, and stir for 1 hour to obtain a mixture C; S5: Add 35% of water to the mixture B in S4 and stir at the maintained temperature for 2 hours to obtain the electroplating additive.

[0042] (III) Preparation of graphene and carbon nanotube doped silver plating solution: S6: Add 2 / 3 volume of pure water into the electroplating tank; S7: Add 80-150g / L potassium cyanide to the pure water in S6, heat to 40 degrees and stir to dissolve; S8: Add 20-50 g / L silver cyanide to the potassium cyanide solution obtained in S6 and dissolve to obtain a mixture D; S9: adding 15-30 g / L potassium carbonate to the mixture D obtained in S7 to dissolve and obtain a mixture E; S10: adding 70-90 g / L of graphene and carbon nanotube composite powder and 5-12 g / L of electroplating additive to the mixture E obtained in S9, stirring and dissolving to obtain a mixture F; S11: adding the remaining amount of water to a standard volume of 200 L, and cooling the solution to 16-25° C. to obtain the desired graphene and carbon nanotube doped silver plating solution; The graphene and carbon nanotube doped silver plating solution prepared by the present invention is used to plate a silver layer on the surface of a pre-plated part. The process parameters to be controlled during the electroplating process are as follows: pH is 12-14, the use temperature is 16-25°C, the silver ion content in the bath is 20-50g / L, the graphene and carbon nanotube composite powder content is 70-90g / L, and the plating solution does not need to be filtered during use. 15g of graphene and carbon nanotube composite powder can be added for every 2kg of silver plated. After the electroplating is completed, the conductivity (contact resistance), wear cycle, and Vickers hardness test results of the product are 0.1mΩ, 2050 cycles, and 233.7HV, respectively.

[0043] Example 4: The preparation process of the graphene and carbon nanotube doped silver plating solution provided by the present invention is as follows: 1. Preparation of graphene and carbon nanotube composite powder: S1: Weigh 55% of graphene and carbon nanotubes in a ratio of 1.3:1 and put them into a stirrer, add 21% of a mixture of PVA and TPO, and stir for 5 hours to dissolve the solids to obtain a mixture A; S2: Spread the mixture A obtained in S1 on a tray, put it into an oven and bake it at 75°C for 2.5 hours, and completely dry it to obtain the graphene and carbon nanotube composite powder; (II) Preparation of electroplating additives: S3: Add 29% of the mixture of PEG and OP to 20% of water and stir well to obtain mixture B; S4: Add 14% of a mixture of PVA and TPO and 8% of a mixture of GL and SS to the mixture B in S3, control the temperature to 40°C, and stir for 1 hour to obtain a mixture C; S5: Add 29% of water to the mixture B in S4 and stir at the maintained temperature for 3 hours to obtain the electroplating additive.

[0044] (III) Preparation of graphene and carbon nanotube doped silver plating solution: S6: Add 2 / 3 volume of pure water into the electroplating tank; S7: Add 80-150g / L potassium cyanide to the pure water in S6, heat to 40 degrees and stir to dissolve; S8: Add 20-50 g / L silver cyanide to the potassium cyanide solution obtained in S6 and dissolve to obtain a mixture D; S9: adding 15-30 g / L potassium carbonate to the mixture D obtained in S7 to dissolve and obtain a mixture E; S10: adding 70-90 g / L of graphene and carbon nanotube composite powder and 5-12 g / L of electroplating additive to the mixture E obtained in S9, stirring and dissolving to obtain a mixture F; S11: adding the remaining amount of water to a standard volume of 200 L, and cooling the solution to 16-25° C. to obtain the desired graphene and carbon nanotube doped silver plating solution; The graphene and carbon nanotube doped silver plating solution prepared by the present invention is used to plate a silver layer on the surface of a pre-plated part. The process parameters to be controlled during the electroplating process are as follows: pH is 12-14, the use temperature is 16-25°C, the silver ion content in the bath is 20-50g / L, the graphene and carbon nanotube composite powder content is 70-90g / L, and the plating solution does not need to be filtered during use. 15g of graphene and carbon nanotube composite powder can be added for every 2kg of silver plated. After the electroplating is completed, the conductivity (contact resistance), wear cycle, and Vickers hardness test results of the product are 0.22mΩ, 2250 cycles, and 282.5HV, respectively.

[0045] Example 5: The preparation process of the graphene and carbon nanotube doped silver plating solution provided in this application is as follows: 1. Preparation of graphene and carbon nanotube composite powder: S1: Weigh 60% of graphene and carbon nanotubes in a ratio of 1.4:1 and put them into a stirrer, add 23% of a mixture of TPO and TP and 17% of EA, and stir for 6 hours to dissolve the solids to obtain a mixture A; S2: Spread the mixture A obtained in S1 on a tray, put it into an oven and bake it at 80° C. for 3 hours, and completely dry it to obtain the graphene and carbon nanotube composite powder; (II) Preparation of electroplating additives: S3: Add 32% of the mixture of TX and OP to 20% of water and stir well to obtain mixture B; S4: Add 16% of a mixture of TPO and TP and 9% of a mixture of CMC and SS to the mixture B in S3, control the temperature to 45°C, and stir for 1 hour to obtain a mixture C; S5: Add 23% of water to the mixture B in S4 and stir at the maintained temperature for 3 hours to obtain the electroplating additive.

[0046] (III) Preparation of graphene and carbon nanotube doped silver plating solution: S6: Add 2 / 3 volume of pure water into the electroplating tank; S7: Add 80-150g / L potassium cyanide to the pure water in S6, heat to 40 degrees and stir to dissolve; S8: Add 20-50 g / L silver cyanide to the potassium cyanide solution obtained in S6 and dissolve to obtain a mixture D; S9: adding 15-30 g / L potassium carbonate to the mixture D obtained in S7 to dissolve and obtain a mixture E; S10: adding 70-90 g / L of graphene and carbon nanotube composite powder and 5-12 g / L of electroplating additive to the mixture E obtained in S9, stirring and dissolving to obtain a mixture F; S11: adding the remaining amount of water to a standard volume of 200 L, and cooling the solution to 16-25° C. to obtain the desired graphene and carbon nanotube doped silver plating solution; The graphene and carbon nanotube doped silver plating solution prepared by the present invention is used to plate a silver layer on the surface of a pre-plated part. The process parameters to be controlled during the electroplating process are as follows: pH is 12-14, the use temperature is 16-25°C, the silver ion content in the bath is 20-50g / L, the graphene and carbon nanotube composite powder content is 70-90g / L, and the plating solution does not need to be filtered during use. 15g of graphene and carbon nanotube composite powder can be added for every 2kg of silver plated. After the electroplating is completed, the conductivity (contact resistance), wear cycle, and Vickers hardness test results of the product are 0.3mΩ, 1850 cycles, and 202.5HV, respectively.

[0047] Example 6: The preparation process of the graphene and carbon nanotube doped silver plating solution provided in this application is as follows: 1. Preparation of graphene and carbon nanotube composite powder: S1: Weigh 65% of graphene and carbon nanotubes in a ratio of 1.5:1 and put them into a stirrer, add 25% of a mixture of PVA and TP and 10% of EA, and stir for 6 hours to dissolve the solids to obtain a mixture A; S2: Spread the mixture A obtained in S1 on a tray, put it into an oven and bake it at 80° C. for 3 hours, and completely dry it to obtain the graphene and carbon nanotube composite powder; (II) Preparation of electroplating additives: S3: Add 35% of the mixture of PEG and TX into 20% of water and stir to obtain mixture B; S4: Add 17% of the mixture of PVA and TP and 10% of the mixture of GL and CMC to the mixture B in S3, control the temperature to 50°C, and stir for 1 hour to obtain a mixture C; S5: Add 18% of water to the mixture B in S4 and stir at the maintained temperature for 3 hours to obtain the electroplating additive.

[0048] (III) Preparation of graphene and carbon nanotube doped silver plating solution: S6: Add 2 / 3 volume of pure water into the electroplating tank; S7: Add 80-150g / L potassium cyanide to the pure water in S6, heat to 40 degrees and stir to dissolve; S8: Add 20-50 g / L silver cyanide to the potassium cyanide solution obtained in S6 and dissolve to obtain a mixture D; S9: adding 15-30 g / L potassium carbonate to the mixture D obtained in S7 to dissolve and obtain a mixture E; S10: adding 70-90 g / L of graphene and carbon nanotube composite powder and 5-12 g / L of electroplating additive to the mixture E obtained in S9, stirring and dissolving to obtain a mixture F; S11: adding the remaining amount of water to a standard volume of 200 L, and cooling the solution to 16-25° C. to obtain the desired graphene and carbon nanotube doped silver plating solution; The graphene and carbon nanotube doped silver plating solution prepared by the present invention is used to plate a silver layer on the surface of a pre-plated part. The process parameters to be controlled during the electroplating process are as follows: pH is 12-14, the use temperature is 16-25°C, the silver ion content in the bath is 20-50g / L, the graphene and carbon nanotube composite powder content is 70-90g / L, and the plating solution does not need to be filtered during use. 15g of graphene and carbon nanotube composite powder can be added for every 2kg of silver plated. After the electroplating is completed, the conductivity (contact resistance), wear cycle, and Vickers hardness test results of the product are 0.17mΩ, 1950 cycles, and 213.5HV, respectively.

[0049] The products plated by the graphene and carbon nanotube doped silver plating solution (YCYY-35) prepared by the technical solution of the present invention and the conventional silver plating solutions X, Y, and Z on the market, the four systems are respectively plated with silver layers on the same workpiece surface using their optimal process parameters. After the electroplating is completed, the conductivity (contact resistance), wear resistance (wear cycle), and hardness (Vickers hardness) of the coating are tested. The attached partial preferred results are compared. Figure 4 As shown in the table.

[0050] The graphene and carbon nanotube doped silver plating solution prepared by the technical solution of the present invention is most particularly characterized in that it contains graphene and carbon nanotube composite powder, which has a significant enhancing effect on the wear resistance, conductivity and hardness of the silver plating layer. Dispersants and stabilizers can increase the dispersibility and stability of various components in the silver plating solution, so that the silver layer on the surface of the final product is deposited more evenly and smoothly. Compared with the products prepared by the traditional cyanide silver plating system, the silver-plated products prepared by the silver plating solution have stronger silver layer adhesion, smoother surface, better wear resistance, better conductivity and higher hardness, and the overall quality of the silver-plated products is improved. The conductivity, wear resistance and hardness of the coating implemented by the graphene and carbon nanotube doped silver plating solution prepared by the technical solution of the present invention are greatly improved compared with the coating implemented by the traditional silver plating solution. The production process and use process of the graphene and carbon nanotube doped silver plating solution prepared by the technical solution of the present invention do not require high temperature, the production and use energy consumption is low, it is easy to achieve large-scale production and application, and has excellent economic benefits.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A graphene and carbon nanotube doped silver plating solution, characterized in that: The invention comprises 20-50 g / L of silver cyanide, 80-150 g / L of potassium cyanide, 15-30 g / L of potassium carbonate, 70-90 g / L of graphene and carbon nanotube composite powder, 5-12 g / L of electroplating additive and the balance of water; wherein the graphene and carbon nanotube composite powder comprises 40-65% of the graphene and carbon nanotubes in a ratio of 1:1-1.5:1, 15-25% of a dispersant and the balance of an organic solvent; and the electroplating additive comprises 20-35% of a surfactant, 8-17% of a dispersant, 5-10% of a stabilizer and the balance of water.

2. The graphene and carbon nanotube doped silver plating solution according to claim 1, characterized in that: The graphene is a single-layer graphene with a purity of more than 98%.

3. The graphene and carbon nanotube doped silver plating solution according to claim 1, characterized in that: The carbon nanotubes are multi-walled carbon nanotubes with a diameter of 50-100 nm and a length of 1-200 μm.

4. The graphene and carbon nanotube doped silver plating solution according to claim 1, characterized in that: The dispersant is one or more mixtures of polyvinyl alcohol (PVA) or polyacrylate (TPO) or triethylhexyl phosphoric acid (TP).

5. The graphene and carbon nanotube doped silver plating solution according to claim 1, characterized in that: The organic solvent is one of N,N-dimethylformamide (DMF), tetrahydrofuran (THF) or ethyl acetate (EA).

6. The graphene and carbon nanotube doped silver plating solution according to claim 1, characterized in that: The surfactant is a mixture of one or more of polyethylene glycol-400 (PEG), Triton X-114 (TX), or nonylphenol polyoxyethylene ether (OP).

7. The graphene and carbon nanotube doped silver plating solution according to claim 1, characterized in that: The stabilizer is one or more mixtures of glycerol (GL) or carboxymethyl cellulose (CMC) or sodium stearate (SS).

8. The graphene and carbon nanotube doped silver plating solution according to claim 1, characterized in that: The water in the electroplating additive is deionized water, distilled water or double distilled water.

9. A method for preparing a graphene and carbon nanotube doped silver plating solution, characterized in that: The following steps are involved:

1. Preparation of graphene and carbon nanotube composite powder: S1: Weigh 40-65% of graphene and carbon nanotubes in a ratio of 1:1-1.5:1 and put them into a stirrer, add 15-25% of a dispersant and the remainder of an organic solvent, and stir for 4-6 hours to dissolve the solids to obtain a mixture A; S2: Spread the mixture A obtained in S1 on a tray, put it into an oven and bake it at 70-80° C. for 2-3 hours, and completely dry it to obtain the graphene and carbon nanotube composite powder; (II) Preparation of electroplating additives: S3: Add 20-35% of surfactant to 20% of water and stir to obtain mixture B; S4: add 8-17% of dispersant and 5-10% of stabilizer to the mixture B in S3, control the temperature to 30-50°C, and stir for 1 hour to obtain a mixture C; S5: Add the remaining amount of water to the mixture B in S4, maintain the temperature and stir for 2-3 hours to obtain an electroplating additive; (III) Preparation of graphene and carbon nanotube doped silver plating solution: S6: Add 2 / 3 volume of pure water into the electroplating tank; S7: Add 80-150g / L potassium cyanide to the pure water in S6, heat to 40 degrees and stir to dissolve; S8: Add 20-50 g / L silver cyanide to the potassium cyanide solution obtained in S6 and dissolve to obtain a mixture D; S9: adding 15-30 g / L potassium carbonate to the mixture D obtained in S7 to dissolve and obtain a mixture E; S10: adding 70-90 g / L of graphene and carbon nanotube composite powder and 5-12 g / L of electroplating additive to the mixture E obtained in S9, stirring and dissolving to obtain a mixture F; S11: Add the remaining amount of water to a standard volume of 200 L, and cool the temperature to 16-25° C. to obtain the required graphene and carbon nanotube doped silver plating solution.

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