A method of electrodeposition of silver

Abstract

The present application relates to the technical field of electrodeposition, and particularly relates to a method for electrodeposition of silver. The method for electrodeposition of silver comprises the following steps: placing a substrate in an electrolyte, and performing electrodeposition by using a constant potential method to obtain a silver plating layer; wherein the electrolyte comprises a eutectic ionic liquid, an additive and a silver source; and the additive comprises at least one of a chloride salt, a nitrogen-containing heterocyclic compound and an amine compound. The method for electrodeposition of silver provided by the present application can significantly improve the quality of the prepared silver plating layer by using a specific electrolyte, especially by adding a specific additive, so that the color of the prepared silver plating layer is silver white without yellowing, the thickness is appropriate, and the adhesion and the discoloration resistance of the plating layer can be enhanced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrodeposition, in particular to a method for electrodeposition of silver. BACKGROUND

[0002] Silver has been widely used in microelectronic industry, catalyst field, sensor field and preparation of magnetic resistance material due to its excellent corrosion resistance, lubricity, decoration, antibacterial property, high conductivity, high catalytic property, high sensitivity to environment and the like.

[0003] Nanomaterials have become a research hotspot due to their unique physical and chemical properties and broad application prospects. As an important functional material, nanosilver has been widely used in ceramic materials, environmental protection materials and coatings and many other fields. The synthesis methods of nanosilver include chemical reduction method, ultrasonic method, photo-reduction method and electrochemical reduction method. Electrodeposition method is suitable for many nanocrystalline materials, and nanocrystalline materials prepared by electrodeposition method can be quickly prepared and have stable properties. The selection of electrolyte plays a crucial role.

[0004] With the improvement of people's environmental protection consciousness and the proposal of green chemistry concept, novel ionic liquid (ILs) electrolyte has attracted much attention. Ionic liquid is a molten salt system composed of specific organic cations and inorganic anions, which is liquid at room temperature or near room temperature, and is a new type of medium and "soft" functional material. Due to its low melting point, wide electrochemical window, high stability, selective solubility and designability, it is used for the deposition of copper, zinc, chromium, silver and other metals and alloys.

[0005] In recent years, eutectic ionic liquid (also known as deep eutectic solvent, DESs) has become a green alternative to traditional ILs and aqueous solution due to its unique advantages of non-toxicity, low cost and high purity. The most common eutectic ionic liquid is a mixture of urea and choline chloride, which has a freezing point of 12℃ and is still liquid at room temperature. The greenness and sustainability of this new type of solvent lies in the fact that both of its components are inexpensive, biodegradable, non-toxic and widely used in nature. Without the need for expensive artificial and equipment, they can be easily mixed to form high-purity solvents.

[0006] The electrolyte composition of conventional aqueous solution system is complex, and additives such as brightener, main complexing agent, auxiliary complexing agent and leveling agent need to be added. However, these organic additives will make the solution composition more complex, cause the solution to be unstable, make the recovery and treatment of the plating solution difficult, and pollute the environment.

[0007] However, the silver coating obtained by conventional eutectic ionic liquid deposition often has problems such as yellow color, poor adhesion and poor anti-discoloration ability, which cannot meet the process use requirements.

[0008] In view of the above, the present application is provided. SUMMARY

[0009] The first object of the present application is to provide a method for electrodepositing silver, which can significantly improve the quality of the prepared silver coating, make the color of the prepared silver coating silver-white without yellowing, and make the thickness suitable, and at the same time, can enhance the adhesion of the coating and its anti-color change ability.

[0010] In order to achieve the above object of the present application, the following technical solutions are adopted:

[0011] The present application provides a method for electrodepositing silver, comprising the following steps:

[0012] The substrate is placed in the electrolyte, and electrodepositing is carried out by using the constant potential method to obtain a silver coating.

[0013] The electrolyte comprises a eutectic ionic liquid, an additive and a silver source.

[0014] The additive comprises at least one of a chloride salt, a nitrogen-containing heterocyclic compound and an amine compound.

[0015] In some specific embodiments of the present application, the additive can be selected from one of a chloride salt, a nitrogen-containing heterocyclic compound and an amine compound, or a mixture of any of the above.

[0016] The present application significantly improves the quality of the prepared silver coating by using a specific electrolyte, especially by adding a specific additive, the color of the prepared silver coating is silver-white without yellowing, and the thickness is suitable; and the adhesion of the coating to the substrate and the anti-color change ability of the silver coating are significantly enhanced.

[0017] At the same time, the electrolyte provided by the present application can be reused, and recycling not only can save costs and avoid resource waste, but also solves the problems of complex composition, difficulty in recycling and processing of conventional aqueous solution systems in the prior art.

[0018] Specifically, the mechanism of the present application for improving the quality of the silver coating, enhancing the adhesion of the coating to the substrate and the anti-color change ability of the coating by using a specific electrolyte and adding a specific additive is as follows:

[0019] The specific additive is added to make silver ions exist in the form of complex in the plating solution, so that the silver ions can present larger electrochemical polarization during deposition. The size of the electrochemical polarization is related to the energy change of the ligand around the central ion when the ligand is transformed. The energy change of the silver complex ion existing in the electrolyte when it is transformed into an activated complex is larger, and the activation energy required during reduction is higher, which leads to the increase of the electrochemical polarization, and the quality of the obtained plating layer is better. In addition, the coordination reaction occurs between the additive adsorbed on the cathode surface and the silver complex ion in the solution, and the surface complex is formed on the metal surface. The formation of the surface complex makes the discharge of the metal ion more difficult, and the overvoltage of the reaction is also obviously increased, which is beneficial to the formation of new crystal nucleus, and the silver crystal grains obtained are relatively small.

[0020] In addition, the silver plating layer with different crystal nucleus sizes can be obtained by adding different types and amounts of additives, and different deposition effects can be obtained. + The d 10 electronic configuration of Ag + is full, and it forms all the electrovalence (or outer orbital) complexes. The lone pair electrons of the ligand can only enter the outer orbital of Ag -1 , so it is active in the electronic substitution reaction. In the electrode reaction kinetics, the electrode reduction reaction is faster, and the electrode reaction rate constant value is also the highest (≥10 -1 s + ) in the metal ions. In order to greatly reduce the electrode reaction rate of Ag -1 , the additive is added to form a complex with the silver ion to control the growth speed and direction of the crystal nucleus, so that the silver plating layer with different crystal nucleus sizes can be obtained, and different deposition effects can be obtained.

[0021] Preferably, the eutectic ionic liquid comprises a mixture of choline chloride and urea, at least one of 1-ethyl-3-methylimidazolium tetrafluoroborate and 1-ethyl-3-methylimidazolium hexafluorophosphate.

[0022] The eutectic ionic liquid, also known as a low eutectic solvent, is a two-component or three-component eutectic mixture composed of a certain stoichiometric ratio of a hydrogen bond acceptor and a hydrogen bond donor, and the freezing point is significantly lower than the melting point of the pure substance of each component.

[0023] The eutectic ionic liquid as the solvent has the advantages of non-toxicity, low cost, easy preparation and biodegradability.

[0024] Preferably, the chloride salt comprises ammonium chloride and / or potassium chloride.

[0025] The chloride salt refers to the general term of salts with chloride as anion.

[0026] The [AgCl2] -1The complex can control the growth speed and direction of the crystal nucleus, so that silver plating layers with different crystal nucleus sizes are obtained.

[0027] And / or, the nitrogen-containing heterocyclic compound includes at least one of 5,5-dimethylhydantoin, hydantoin and 5-methylhydantoin.

[0028] The nitrogen-containing heterocyclic compound refers to a heterocyclic compound containing a nitrogen atom. The heterocyclic compound is an organic compound containing a heterocyclic structure in the molecule, and the atoms constituting the ring contain at least one heteroatom in addition to carbon atoms. It is the largest class of organic compounds, and the most common heteroatom is nitrogen, sulfur and oxygen.

[0029] 5,5-dimethylhydantoin, chemical formula C5H8N2O2, also known as dimethylhydantoin, 5,5-dimethylimidazolidine and DMH. Mainly used as a disinfectant, epoxy resin and amino acid raw material.

[0030] Hydantoin is an organic compound with the molecular formula C3H4N2O2, mainly used in chemical industry, medicine, textile, biochemistry and other fields, also known as hydantoin and 2,4-imidazoline dione.

[0031] 5-methylhydantoin is a chemical substance with the molecular formula C4H6N2O2. Also known as 5-methylhydantoin.

[0032] And / or, the amine compound includes ethylenediamine and / or ethylenediaminetetraacetic acid.

[0033] Ethylenediamine, abbreviated as EDA, has the chemical formula C2H8N2, which is a typical aliphatic diamine, colorless or slightly yellow oil or water-like transparent liquid.

[0034] Ethylenediaminetetraacetic acid (EDTA) belongs to the derivative of aliphatic diamine, and its chemical formula is C 10 H 16 N2O8, white powder at room temperature and normal pressure.

[0035] The applicant accidentally found that the concentration of ammonium chloride will affect the performance of the plating layer. When the concentration of ammonium chloride is within a certain range, the performance of the plating layer is better, but the adhesion between the plating layer and the substrate is poor at this time.

[0036] Therefore, by using specific additives, i.e. using specific types of nitrogen-containing heterocyclic compounds and amine compounds, the adhesion between the plating layer and the substrate can be improved while ensuring the color and anti-color change ability of the plating layer. The obtained plating layer is not easy to fall off, and is not easy to have the phenomenon of peeling or bubbling.

[0037] Preferably, the silver source includes silver nitrate and / or silver chloride.

[0038] When silver nitrate is used as the silver source, the ionized silver ions combine with other silver ions to form [AgCl2]. -1 Complex.

[0039] Using silver chloride as the silver source, silver chloride is sparingly soluble in aqueous solution, but it can be readily dissolved into Ag in ionic liquid systems by heating and stirring. + Cl - .

[0040] Preferably, the molar concentration of the additive in the electrolyte is 0.1 to 0.6 mol / L.

[0041] In this application, the concentration of additives affects the growth rate and direction of crystal nuclei, thereby affecting the deposition effect, such as changing the quality of the silver plating (including color and silver size), the adhesion between the plating and the substrate, and the plating's resistance to discoloration.

[0042] Using the above-mentioned range of molar concentrations is beneficial for obtaining silver plating layers with superior performance.

[0043] Preferably, the potential used in the constant potential method is -1.0 to -0.7V, including but not limited to any one of -0.95V, -0.9V, -0.85V, -0.8V, and -0.75V, or any range between two of them.

[0044] Deposition potential can also affect the growth rate and direction of crystal nuclei, thereby altering the electrodeposition effect.

[0045] Using the potential within the above range is beneficial for further improving the performance of the silver plating.

[0046] Preferably, the electrodeposition time is 20 to 60 minutes; including but not limited to any one of 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, and 55 minutes, or any range between two of them.

[0047] Preferably, during the electrodeposition process, the temperature of the electrolyte is 40 to 60°C, including but not limited to any one of 42°C, 45°C, 48°C, 50°C, 53°C, 56°C, and 59°C, or a range between any two.

[0048] The electrodeposition time and the electrolyte temperature during the electrodeposition process both have a certain impact on the electrodeposition effect. By adopting the electrodeposition time and electrolyte temperature mentioned above, the performance of the silver plating layer can be further improved.

[0049] Furthermore, the silver electrodeposition method provided by this invention uses a low electrolyte temperature and consumes less energy, which is beneficial for energy saving and cost reduction.

[0050] Preferably, the matrix comprises a copper alloy and / or carbon steel;

[0051] Preferably, the copper alloy comprises brass and / or copper.

[0052] The type of substrate has a significant impact on the electrodeposition effect, especially the adhesion between the coating and the substrate. Using the aforementioned types of substrates helps to enhance the adhesion between the coating and the substrate.

[0053] Preferably, a three-electrode system is used in the electrodeposition process;

[0054] The three-electrode system uses the substrate as the working electrode, the Ag / AgCl electrode as the reference electrode, and the platinum electrode as the auxiliary electrode.

[0055] The three electrodes refer to the working electrode, the reference electrode, and the auxiliary electrode. Using a three-electrode system can more accurately control the potential difference and reduce errors.

[0056] Preferably, the average grain size D50 of the silver in the silver plating layer is 0.1 to 2.5 μm, including but not limited to any one of 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.8 μm, 1.0 μm, 1.3 μm, 1.6 μm, 1.9 μm, 2 μm, 2.2 μm, and 2.4 μm, or a range between any two.

[0057] By changing various parameters in the electrodeposition process, especially the type and amount of additives and the deposition potential, the growth rate and direction of the crystal nuclei can be controlled, thereby obtaining silver coatings with different crystal nuclei sizes.

[0058] In some specific embodiments of the present invention, the silver coating obtained by the present invention is micro-nano silver particles in the form of microspheres.

[0059] In some specific embodiments of the present invention, the method for preparing the electrolyte includes: mixing choline chloride and urea evenly, and then adding a silver source and an additive thereto in sequence;

[0060] Preferably, during the process of uniformly mixing choline chloride and urea, the temperature of the mixture is 70-90°C; including but not limited to any one of 72°C, 75°C, 77°C, 80°C, 85°C, and 88°C, or any range between two of them.

[0061] Preferably, the choline chloride and the urea are mixed evenly by stirring.

[0062] More preferably, the stirring speed is 400 to 600 r / min, including but not limited to any one of 450 r / min, 500 r / min, and 550 r / min, or any range between two of them.

[0063] More preferably, the stirring time is 2 to 5 hours, including but not limited to any one of 2.5 hours, 3 hours, 3.5 hours, 4 hours, and 4.5 hours, or any range between two of them.

[0064] Preferably, in the mixture of choline chloride and urea, the molar ratio of choline chloride to urea is 1:1 to 5 (1:2, 1:3 or 1:4 can also be selected); more preferably, it is 1:2.

[0065] In some specific embodiments of the present invention, the substrate undergoes pretreatment, which specifically includes: grinding, washing and activating the substrate in sequence.

[0066] Preferably, the polishing specifically includes: polishing with sandpaper of grits of 240, 400, 1200 and 2000 in sequence;

[0067] Preferably, water is used for the washing; more preferably, the water includes deionized water.

[0068] Preferably, the activation solution used for activation is an acid solution;

[0069] Preferably, the acid solution includes dilute hydrochloric acid and / or dilute sulfuric acid;

[0070] Preferably, the activation time is 20 to 60 seconds, including but not limited to any one of 25 seconds, 30 seconds, 35 seconds, 40 seconds, 45 seconds, 50 seconds, and 55 seconds, or any range between two of them.

[0071] In some specific embodiments of the present invention, after activation, the following steps are further included: ultrasonic treatment of the activated working electrode, followed by washing with water;

[0072] Preferably, the frequency of the ultrasonic wave is 20 to 40 kHz, including but not limited to the point value of any one of 25 kHz, 30 kHz, 35 kHz, and 38 kHz, or the range between any two.

[0073] Preferably, the ultrasonic treatment time is 5 to 30 minutes, including but not limited to the point value of any one of 10 minutes, 15 minutes, 20 minutes, and 25 minutes, or the range between any two.

[0074] By pre-treating the substrate, impurities on the substrate surface can be removed, making the surface smooth, uniform, and clean.

[0075] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0076] (1) The method for electrodepositing silver provided by the present invention can significantly improve the quality of the silver plating by using an electrolyte with a specific composition, especially by adding a specific type of additive. The silver plating is silvery-white in color and has a suitable thickness. It can also enhance the bonding force between the plating and the substrate and enhance the anti-discoloration ability of the silver plating.

[0077] (2) The method for electrodepositing silver provided by the present invention can obtain silver coatings with different crystal nuclei sizes by changing the type and amount of additives, thereby changing the deposition effect.

[0078] (3) The method for electrodepositing silver provided by the present invention can change the deposition effect by changing the deposition potential used in the constant potential method.

[0079] (4) The method for electrodepositing silver provided by the present invention has the advantages of non-toxic, low cost, easy preparation and biodegradability of electrolyte, and can also be recycled, saving preparation cost and processing cost and avoiding resource waste. Attached Figure Description

[0080] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0081] Figure 1 XRD pattern of the silver coating obtained in Example 1 of this invention;

[0082] Figure 2 EDX image of the silver plating layer obtained in Example 1 of this invention;

[0083] Figure 3 SEM image of the silver coating obtained in Example 1 of this invention;

[0084] Figure 4 XRD pattern of the silver plating layer prepared in Comparative Example 1 provided by the present invention;

[0085] Figure 5 EDX image of the silver plating layer prepared in Comparative Example 1 provided by the present invention;

[0086] Figure 6 SEM image of the silver coating obtained in Comparative Example 1 provided by the present invention. Detailed Implementation

[0087] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0088] Example 1

[0089] The method for electrodepositing silver provided in this embodiment includes the following steps:

[0090] (1) Mix 13.9g of choline chloride and 12g of urea (the molar ratio of choline chloride to urea is 1:2) in a beaker until homogeneous. Then place the mixture in a 70℃ oil bath and stir continuously (stirring speed is 500r / min) until it becomes transparent and clear to obtain a eutectic ionic liquid. Then add 0.82g of silver nitrate and 0.4g of NH4Cl to it in sequence and stir until homogeneous to obtain an electrolyte (the molar concentration of NH4Cl in the electrolyte is 0.3mol / L).

[0091] (2) The brass substrate was polished with 240 grit, 400 grit, 1200 grit and 2000 grit sandpaper in sequence, and then cleaned with deionized water. It was then activated in a mixture of dilute hydrochloric acid and dilute sulfuric acid at room temperature for 30 seconds. Then it was ultrasonically cleaned at room temperature for 10 minutes (the frequency of the ultrasonic wave was 28 kHz), and then cleaned with deionized water to obtain the pretreated brass substrate.

[0092] (3) A three-electrode system was adopted, with the pretreated brass substrate obtained in step (2) as the working electrode, the Ag / AgCl electrode as the reference electrode, and the platinum electrode as the auxiliary electrode. Electrodeposition was carried out by constant potential method, with a deposition potential of -0.8V, an electrolyte temperature of 50℃ during deposition, and a deposition time of 30min. After deposition, a silver plating layer was obtained on the substrate surface.

[0093] Example 2

[0094] The method for electrodepositing silver provided in this embodiment is basically the same as that in Example 1, except that in step (1), the amount of NH4Cl added is replaced with 0.82g, that is, the molar concentration of NH4Cl in the electrolyte is 0.6mol / L.

[0095] Example 3

[0096] The method for electrodepositing silver provided in this embodiment is basically the same as that in Example 1, except that in step (1), the amount of NH4Cl added is replaced with 0.13g, that is, the molar concentration of NH4Cl in the electrolyte is 0.1mol / L.

[0097] Example 4

[0098] The method for electrodepositing silver provided in this embodiment is basically the same as that in Example 1, except that in step (1), the additive NH4Cl is replaced with DMH (the molar concentration of DMH in the electrolyte is 0.8 mol / L).

[0099] Example 5

[0100] The method for electrodepositing silver provided in this embodiment is basically the same as that in Example 1, except that in step (1), the additive NH4Cl is replaced with EDTA (the molar concentration of EDTA in the electrolyte is 0.075 mol / L).

[0101] Example 6

[0102] The method for electrodepositing silver provided in this embodiment is basically the same as that in Example 1, except that in step (1), 0.4g NH4Cl is replaced with a mixture of 2.56g DMH and 0.18g EDTA.

[0103] Example 7

[0104] The method for electrodepositing silver provided in this example is basically the same as that in Example 1, except that in step (1), 0.4g NH4Cl is replaced with a mixture of 1.96g hydantoin and 0.037g ethylenediamine.

[0105] Comparative Example 1

[0106] The method for electrodepositing silver provided in this comparative example is basically the same as that in Example 1, except that NH4Cl is not added in step (1).

[0107] Comparative Example 2

[0108] The method for electrodepositing silver provided in this comparative example is basically the same as that in Example 6, except that in step (3), the deposition potential is replaced with -0.6V.

[0109] Comparative Example 3

[0110] The method for electrodepositing silver provided in this comparative example is basically the same as that in Example 6, except that in step (3), the deposition potential is replaced with -1.5V.

[0111] Comparative Example 4

[0112] The method for electrodepositing silver provided in this comparative example is basically the same as that in Example 6, except that in step (2), the substrate is replaced with a nickel sheet.

[0113] Experimental Example 1

[0114] The silver coating obtained in Example 1 was analyzed by XRD, EDX, and SEM, and the results are as follows: Figure 1 , Figure 2 and Figure 3 As shown. Among them, Figure 1 XRD pattern of the silver coating obtained in Example 1 of this invention ( Figure 1 Example 1 (as indicated in the text) is Example 1. Figure 2 EDX image of the silver plating layer obtained in Example 1 of this invention ( Figure 2 Example 1 (as indicated in the text) is Example 1. Figure 3 SEM image of the silver coating obtained in Example 1 of this invention.

[0115] from Figure 1 , Figure 2 and Figure 3 As can be seen, in Example 1 of the present invention, microspherical silver particles were obtained after electrodeposition. XRD results show that the coating is composed of pure silver, and the trace amounts of AgO2 are due to trace amounts of water reduction and AgOH decomposition. EDX results show that the mass percentage of silver is 97%. Therefore, Example 1 of the present invention has prepared a silver coating with microspherical shape and high purity.

[0116] The silver coating obtained in Comparative Example 1 was analyzed by XRD, EDX, and SEM, and the results are as follows: Figure 4 , Figure 5 and Figure 6 As shown. Among them, Figure 4 XRD pattern of the silver plating layer prepared in Comparative Example 1 provided by the present invention; Figure 5 EDX image of the silver plating layer prepared in Comparative Example 1 provided by the present invention; Figure 6 SEM image of the silver coating obtained in Comparative Example 1 provided by the present invention.

[0117] from Figure 4 , Figure 5 and Figure 6 It can be seen that Comparative Example 1 electrodeposited dendritic silver. Due to its dispersed structure, the dendritic silver resulted in poor adhesion and uneven coating. Furthermore, the XRD results of Comparative Example 1 show that the coating is composed of pure silver; the EDX results show that the silver mass percentage is 84% ​​due to the thin coating. Therefore, the silver coating obtained in Comparative Example 1 not only has low purity but also exhibits a dendritic structure.

[0118] Experimental Example 2

[0119] The appearance (including color and thickness), anti-discoloration ability, and adhesion between the silver coatings obtained in the above embodiments and comparative examples were tested and statistically analyzed. The results are shown in Table 1 below.

[0120] Table 1. Test results of appearance, anti-tarnishing properties, and adhesion of silver plating in each group.

[0121]

[0122] By comparing Example 1 and Comparative Example 1 in Table 1, it can be found that the addition of ammonium chloride increases the coating thickness and enhances the resistance to discoloration. Comparing Examples 1, 2, and 3 shows that the concentration of ammonium chloride affects the coating performance; the coating performance is best when the ammonium chloride concentration is 0.3 mol / L, but the adhesion between the coating and the substrate is poor.

[0123] Examples 4, 5, 6, and 7, by changing the type of additives, all improved the adhesion between the coating and the substrate to a certain extent, thus enhancing the coating performance. Example 6, in particular, using DMH as the main complexing agent and EDTA as the auxiliary complexing agent, maximized the improvement of coating performance.

[0124] By comparing Example 6 with Comparative Examples 2, 3, and 4, it can be found that both high and low potentials reduce the coating performance, and no significant coating is observed when a nickel sheet is used as the deposition substrate. This demonstrates that both the deposition potential and the type of substrate affect the coating performance. Using the deposition potential and substrate provided by this invention is beneficial for further improving the coating performance.

[0125] Although the present invention has been illustrated and described with specific embodiments, it should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and scope of the present invention; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such substitutions and modifications that fall within the scope of the present invention are included in the appended claims.

Claims

1. A method for electrodepositing silver, characterized in that, Includes the following steps: The substrate is placed in an electrolyte, and electrodeposition is performed using a constant potential method to obtain a silver plating layer. The electrolyte comprises a eutectic ionic liquid, additives, and a silver source; The additive is a mixture of DMH and EDTA; The eutectic ionic liquid comprises a mixture of choline chloride and urea; In the electrolyte, the molar concentration of the additive is 0.1~0.6 mol / L; The potential used in the constant potential method is -1.0 to -0.7V.

2. The method for electrodepositing silver according to claim 1, characterized in that, The silver source includes silver nitrate and / or silver chloride.

3. The method for electrodepositing silver according to claim 2, characterized in that, The electrodeposition time is 20-60 minutes.

4. The method for electrodepositing silver according to claim 2, characterized in that, During the electrodeposition process, the temperature of the electrolyte is 40~60℃.

5. The method for electrodepositing silver according to claim 2, characterized in that, The substrate includes copper alloys and / or carbon steel.

6. The method for electrodepositing silver according to claim 5, characterized in that, The copper alloy includes brass and / or copper.

7. The method for electrodepositing silver according to claim 2, characterized in that, A three-electrode system is used in the electrodeposition process; The three-electrode system uses the substrate as the working electrode, the Ag / AgCl electrode as the reference electrode, and the platinum electrode as the auxiliary electrode.

8. The method for electrodepositing silver according to claim 2, characterized in that, The average grain size of silver in the silver plating is D50 = 0.1~2.5 μm.

Images