PAM gel polymer electrolyte electroplating liquid for electrogalvanizing and galvanizing process
By using PAM gel polymer electrolyte electroplating solution, the environmental pollution and space limitations of traditional electroplating solutions are solved, achieving uniform deposition of zinc ions and stable electroplating effect, suitable for electroplating needs of complex shapes.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- PINGDINGSHAN UNIVERSITY
- Filing Date
- 2025-12-16
- Publication Date
- 2026-04-14
AI Technical Summary
In existing electroplating zinc processes, traditional electroplating solutions such as cyanide, zincate and chloride zinc plating have environmental pollution and equipment corrosion problems, while sulfate zinc plating system has poor dispersion ability, and traditional aqueous solution electroplating solutions are spatially limited and difficult to adapt to the electroplating requirements of complex shapes.
The PAM gel polymer electrolyte electroplating solution is used. This electroplating solution is composed of PAM polymer backbone, metal salt and liquid plasticizer to form a three-dimensional network structure, which combines the characteristics of liquid and solid electrolytes. By controlling pH value, current density and temperature, uniform deposition of zinc ions can be achieved.
It achieves uniform distribution of zinc ions in electroplating of small and large parts, suppresses hydrogen evolution reaction, provides a stable electroplating environment, is suitable for electroplating complex shapes, and is reusable, reducing the risk of environmental pollution.
Smart Images
Figure CN121853099A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the technical field of electroplating solutions for zinc electroplating, specifically relating to a PAM gel polymer electrolyte electroplating solution and zinc plating process for zinc electroplating. Background Technology
[0002] Electroplating, a traditional metal surface treatment technology, involves depositing zinc metal onto a substrate surface using an electrochemical method. This provides effective corrosion protection for the substrate material while also serving a decorative function. During the electroplating process, zinc ions in the plating bath move towards the cathode (the part to be plated) under the influence of an electric field, gaining electrons on the cathode surface and being reduced to zinc metal. This forms a uniform, dense, and well-bonded zinc deposition layer on the surface of the part—the zinc plating layer. This process requires precise control of factors such as zinc ion concentration, current density, and temperature to ensure the quality of the plating layer, and the electroplating bath is the core of this process. Electroplating zinc processes are also classified according to the type of electroplating solution, currently falling into four main categories: cyanide zinc plating is the traditional process; however, cyanide is a highly toxic substance, posing serious threats to the environment and human health. Zincate zinc plating is an environmentally friendly process evolved from cyanide zinc plating, but its process parameters are complex to control in an alkaline environment. Chloride zinc plating is currently the most widely used in the electroplating industry, producing high-quality coatings, but it is corrosive to equipment in a slightly acidic environment. Sulfate zinc plating has a simple composition, operates in a weakly acidic environment, and has poor dispersion capabilities. Therefore, the electroplating solution is the core of the electroplating process. Traditionally, electroplating has been carried out in aqueous solutions. With the application and promotion of new materials and processes, electroplating zinc technology will continue to develop towards high performance, environmental friendliness, and intelligence. Among these new materials, gel polymer electrolytes as electroplating solutions represent a promising direction.
[0003] Gel polymer electrolytes (GPEs) are ternary systems composed of a polymer backbone, metal salts, and plasticizers (organic solvents). This results in a microstructure consisting of three phase regions: a crystalline phase, an amorphous phase, and a liquid phase. The crystalline phase, composed of the crystalline portions of the polymer, provides mechanical support and strength to the gel. The amorphous phase, composed of the amorphous portions of the polymer swollen with plasticizer, is the primary site for ion transport. The liquid phase, composed of plasticizers and metal salts within the polymer pores, provides ion conduction channels similar to those of liquid electrolytes. GPEs exist in a state between liquid and all-solid electrolytes (jelly-like). The polymer molecules form a three-dimensional network structure through physical or chemical cross-linking, with pores filled with liquid plasticizers and dissolved metal salts. The state of GPEs gives them the advantages of both liquid and solid electrolytes: near-liquid ionic conductivity (due to plasticizer content reaching 70%–80%) and the flexibility and safety of polymer electrolytes. The first use of GPE (polymer-metal-ion battery) was in 1994 by Bellcore, and since then, GPE technology has undergone rapid development and improvement. Since 2017, polyacrylamide (PAM) gel electrolytes have been applied to the development of aqueous zinc-ion batteries. Research has demonstrated the electrochemical properties of zinc ions in PAM gel electrolytes: the three-dimensional network structure of PAM gel can effectively homogenize the Zn ion flow, guiding uniform zinc deposition; modified PAM gel can effectively reduce the reactivity of hydrogen ions in solution, reconstruct the hydrogen bond network, and suppress side reactions (H+) at the source. + The occurrence of ion corrosion.
[0004] From the initial cyanide system to the current diversified and environmentally friendly processes, electroplating technology has continuously adapted to social needs and environmental requirements. The development of electroplating solutions determines the development of the electroplating industry. This invention is the first to research and develop a PAM gel polymer electrolyte electroplating solution for zinc electroplating, which differs from traditional aqueous zinc plating solutions. Summary of the Invention
[0005] The technical problem solved by this invention is to provide a PAM gel polymer electrolyte electroplating solution and zinc plating process for electroplating zinc.
[0006] To solve the above technical problems, the following technical solution is adopted: the raw materials used in the PAM gel polymer electrolyte electroplating solution include acrylamide (AM) monomer, ammonium persulfate (APS), methylenebisacrylamide (MBA), zinc chloride (ZnCl2), potassium chloride (KCl), boric acid (H3BO3), hydrochloric acid (HCl), and zinc plating brightener (Anyang Yinghao (Electroplating) Chemical Co., Ltd., brand: Yinghaole), etc. 1) A chloride zinc plating salt system is adopted, including the main salt (zinc chloride), conductive salt (potassium chloride), buffer (boric acid), and additives (zinc plating brightener); 2) In the PAM gel polymer electrolyte electroplating solution, the acrylamide (AM) monomer used in the raw material polymerizes in the aqueous phase under the initiation of initiators (APS and ZnCl2), while the crosslinking agent (MBA) connects the linear polyacrylamide molecules into a three-dimensional network structure to form a hydrogel. Based on this, the appropriate chloride zinc plating salt system is added to make it ionicly conductive and transform it into a gel electrolyte; 3) The chloride zinc plating process operating parameters are as follows: pH value between 5.0 and 6.0, which can be adjusted with 5wt% to 10wt% dilute hydrochloric acid; working temperature 20 to 30℃; current density controlled at 1 to 3A / dm². Since the prepared PAM gel polymer electrolyte electroplating solution is 2 to 5mm thick, it is easy to heat up when a large current passes through it. According to the temperature of the electroplating area and the quality requirements of the zinc plating layer, the current should not be too large.
[0007] A PAM gel polymer electrolyte electroplating solution for zinc electroplating is disclosed. The electroplating solution is mainly composed of a ternary system consisting of a PAM polymer backbone, a metal salt, and a liquid plasticizer. The PAM polymer backbone is formed by polymerizing acrylamide monomers and forming a three-dimensional network structure through physical or chemical cross-linking. The metal salt is a soluble zinc salt, and the liquid plasticizer is a liquid electrolyte containing a soluble conductive salt. The pores of the three-dimensional network structure of the PAM polymer backbone are filled with the liquid plasticizer containing dissolved metal salt, ultimately forming a PAM gel polymer electrolyte electroplating solution for zinc electroplating. This electroplating solution has a jelly-like consistency and combines the characteristics of both liquid and solid electrolytes.
[0008] Furthermore, the specific preparation process of the PAM polymer skeleton is as follows: first, acrylamide monomer and crosslinking agent methylenebisacrylamide are added to deionized water and stirred to form a mixed solution, then initiator ammonium persulfate and zinc chloride are added, stirred and poured into a glass mold, and a polymerization reaction is initiated under a water bath at 60~80℃ to obtain PAM hydrogel; the PAM hydrogel is soaked and washed with deionized water to remove ammonium persulfate, and then dried to obtain dry PAM hydrogel, i.e., PAM polymer skeleton.
[0009] Furthermore, the mass ratio of acrylamide monomer to deionized water is 1:5; the amount of initiator added is 4wt%~6wt% of the mass of acrylamide monomer, and the mass ratio of ammonium persulfate to zinc chloride in the initiator is 1:1; the amount of crosslinking agent methylenebisacrylamide added is 0.01wt%~0.5wt% of the mass of acrylamide monomer.
[0010] Furthermore, the metal salt is zinc chloride, and the content of the metal salt in the liquid plasticizer containing the dissolved metal salt is 60~90g / L, which is used to provide zinc ions (Zn²⁺) required for electrodeposition.
[0011] Furthermore, the liquid plasticizer is a liquid electrolyte containing conductive salt potassium chloride, wherein the content of conductive salt potassium chloride is 180~230g / L, which is used to improve the conductivity of the solution, improve the deep plating capability, and form a complex with Zn²⁺.
[0012] Furthermore, the electroplating solution also contains a buffer, which is one or more of boric acid or hydrochloric acid, dissolved in a liquid plasticizer at a concentration of 25-35 g / L, to stabilize the pH of the electroplating solution within the optimal range of 4.6-5.6.
[0013] Furthermore, the electroplating solution also contains an additive, which is a zinc plating brightener. The zinc plating brightener is dissolved in a liquid plasticizer at a concentration of 10~20mL / L, and is used to obtain a bright and fine coating core and increase cathode polarization.
[0014] A zinc plating process based on PAM gel polymer electrolyte plating solution, the specific steps of which are as follows: Step S1: Perform pre-plating treatment on the workpiece, and then apply PAM gel polymer electrolyte plating solution to the surface of the workpiece. Step S2: Press the zinc metal sheet onto the outer surface of the other side of the PAM gel polymer electrolyte electroplating solution to form a structure of Zn + PAM electroplating solution + plated part. Connect the anode of the power supply to the zinc metal sheet and the cathode to the plated part, and apply electricity to perform electroplating to complete the zinc electroplating operation. Remove the electrodes and PAM gel polymer electrolyte plating solution, and perform subsequent processing on the plated parts. The PAM gel polymer electrolyte plating solution can be reused. If the main components of the PAM gel polymer electrolyte plating solution have changed after use, the used PAM hydrogel electrolyte plating solution should be soaked again in a liquid plasticizer containing dissolved metal salts before reuse, so as to achieve repeated recycling of the PAM gel polymer electrolyte plating solution.
[0015] Furthermore, the specific process of pre-plating treatment of the workpiece in step S1 is as follows: chemical degreasing → hot water washing → hydrochloric acid solution pickling → cold water rinsing → running water rinsing → cold air drying.
[0016] Furthermore, the process parameters for the electroplating process in step S2 are set as follows: operating temperature 20~30℃; current density controlled at 1~3A / dm²; and the thickness of the prepared PAM gel polymer electrolyte electroplating solution is 2~5mm.
[0017] Table 1. Dosage and Functions of Each Component in PAM Hydrogel Components Dosage Functions and uses Acrylamide monomer (AM) According to the prefabrication volume Forming the polymer backbone and providing basic mechanical properties Initiator (APS) 4wt%~6wt% of monomer mass Initiating free radical polymerization Crosslinking agent (MBA) 0.01wt%~0.5wt% of monomer mass Constructing a three-dimensional network structure Solvent (water) The monomer mass is 4 to 6 times that of the product, and the preparation process involves volatilization. Provides reaction medium and ion transport channels <![CDATA[Additive (ZnCl2)]]> Depending on the requirements of the electroplating process, it can be variable. Specific performance Table 2. Dosage and Functions of Each Component in PAM Gel Electroplating Solution Element Dosage range Main function <![CDATA[Main salt, zinc chloride (ZnCl2)]]> 60~90g / L Provides zinc ions (Zn²⁺) required for electrodeposition. Conductive salt, potassium chloride (KCl) 180~230g / L It improves the solution conductivity, enhances deep plating capability, and forms a complex with Zn²⁺. <![CDATA[Buffer, boric acid (H3BO3)]]> 25~35g / L The optimal pH range for stabilizing the plating solution is 4.6 to 5.6. Additives (zinc plating brightener) 10~20mL / L To achieve a bright, fine coating, increase cathode polarization. The present invention has the following advantages and beneficial effects: 1) The PAM gel polymer electrolyte electroplating solution of the present invention is different from the current aqueous solution electroplating solution. It is used for electroplating of small parts and re-plating of large parts. Its size and shape can be arbitrarily cut and controlled. 2) The PAM gel polymer electrolyte electroplating solution of the present invention can conduct ions quickly like a liquid electroplating solution, and can stabilize the interface like a solid. It can be arbitrarily attached to the plated part without being restricted by spatial position. 3) The PAM gel polymer electrolyte electroplating solution of the present invention "locks in" the liquid phase through its fixed polymer network and can suppress the hydrogen evolution reaction (HER) of aqueous electroplating solutions, which would lead to interfacial disturbance and damage to Zn²⁺. + (Directed migration), thereby creating a calm and stable interface environment and ensuring the uniform distribution of zinc ion flow.
[0018] 4) The polymer chains in the gel of this invention (such as sodium alginate containing carboxyl groups) can not only coordinate with Zn²⁺ through zinc-philic functional groups to provide uniform transport channels, but also reconstruct the hydrogen bond network between water molecules. This "chain-liquid synergistic" effect can optimize the solvation structure of zinc ions and effectively suppress the occurrence of side reactions. Attached Figure Description
[0019] Figure 1 An optical photograph of the PAM gel polymer electrolyte electroplating solution prepared in an embodiment of the present invention.
[0020] Figure 2 SEM results of the preparation of PAM gel polymer electrolyte in this embodiment of the invention.
[0021] Figure 3 XRD pattern of a sample surface with a Zn layer electroplated on a carbon steel plate in an embodiment of the present invention.
[0022] Figure 4 SEM results of the Zn electroplated layer in this embodiment of the invention. Detailed Implementation
[0023] The following examples further illustrate the above-described content of the present invention, but it should not be construed as limiting the scope of the subject matter of the present invention to the following examples. All technologies implemented based on the above-described content of the present invention fall within the scope of the present invention. Example
[0024] The specific steps for electroplating zinc onto carbon steel plates using a PAM gel polymer electrolyte plating solution are as follows: Preparation of PAM gel polymer electrolyte electroplating solution: Step 1: Weigh 35g of acrylamide (AM) monomer and 40mg of crosslinking agent methylenebisacrylamide (MBA), add them to 200mL of deionized water and stir to form a mixed solution. Then weigh 0.2g of ammonium persulfate (APS) and add it to the mixed solution and stir until well mixed. Next, weigh 0.2g of zinc chloride (ZnCl2) and add it to the mixed solution and stir until completely dissolved. Pour the mixed solution into a watch glass and then transfer it to a water bath at 70℃ for reaction. After reacting for 1 hour, PAM hydrogel is obtained. Step 2: After soaking and washing the obtained PAM hydrogel with deionized water, the pH value of the wastewater was measured to be approximately 6.8. 20mm×20mm sheet-shaped PAM hydrogels were cut off; the excess sample was placed in a muffle furnace and dried to obtain dry PAM gel. Step 3: Immerse the cut and cleaned PAM gel in a mixed solution containing zinc chloride (ZnCl2), potassium chloride (KCl), boric acid (H3BO3), and zinc plating brightener. The concentrations of each component are: ZnCl2 80g / L, KCl 200g / L, H3BO3 30g / L, and zinc plating brightener 15mL / L. Adjust the pH of the mixture to between 5.5 and 6.0 with hydrochloric acid and let it stand at room temperature for about 4 hours to obtain the PAM gel polymer electrolyte electroplating solution (if dry PAM gel is used, the standing time is slightly shorter).
[0025] Electro-galvanizing process: Step 1: Pre-plating treatment of carbon steel sheets: chemical degreasing → hot water washing → hydrochloric acid pickling → cold water rinsing → running water rinsing → cold air drying; Step 2: Apply the PAM gel polymer electrolyte electroplating solution prepared above to the surface of the workpiece; Step 3: Press the polished zinc metal sheet onto the other outer surface of the PAM gel polymer electrolyte plating solution, and press it to form the structure of the Zn PAM plating solution plated part; Step 4: Connect the anode of the power supply to the zinc metal sheet and the cathode to the workpiece. Detect the ambient temperature at 24℃. After calculation, design the current density to be 1.5A / dm². Turn on the power supply and turn it off after 10 minutes to complete the electroplating zinc operation.
[0026] Afterwards, the electrodes and PAM gel polymer electrolyte plating solution were removed, and the plated parts were washed with water and dried to obtain samples.
[0027] Test the prepared sample, Figure 1 This is an optical photograph of the prepared PAM gel polymer electrolyte electroplating solution. The sample is semi-transparent and has a thickness of approximately 2.6 mm. Figure 2 The image shows the SEM results of the prepared PAM gel polymer electrolyte. The SEM image reveals a network-interconnected porous structure of the hydrogel, which enables the gel electrolyte to not only store a large amount of electrolyte, but also provides a smooth path for ion migration, thereby improving its ionic conductivity. Figure 3 The XRD pattern is the surface of a sample after Zn layer is electroplated on a carbon steel plate. XRD analysis shows that Zn is the main component of the sample surface layer. There are diffraction peaks of iron and weaker peaks of other impurities, indicating that Zn metal is well deposited on the surface of the plated part. The presence of diffraction peaks of iron indicates that the coating layer is not thick. Figure 4 These are the SEM results of the Zn electroplated layer prepared by the PAM gel polymer electrolyte electroplating solution. The SEM images show Zn crystals with columnar or cuboid morphology, clearly demonstrating its typical hexagonal close-packed crystal structure. The crystal particles are uniform in size and orderly distributed, but voids are present. (Comparison...) Figure 2 It is known that these voids are caused by the PAM gel polymer backbone being occupied.
[0028] Because PAM (polyacrylamide) gel polymers undergo hydrolysis with alkalis, the amide groups (-CONH2) on its molecular chain hydrolyze under alkaline conditions, transforming into negatively charged carboxyl groups (-COO⁻). This process significantly alters the properties of PAM. The generated carboxyl groups carry a negative charge, converting the originally electrically neutral nonionic PAM into anionic PAM. The negatively charged carboxyl groups on the molecular chain, due to electrostatic repulsion, cause the originally coiled molecular chains to unwind, increasing its hydrodynamic volume in solution and its contact opportunities with particles. This leads to increased viscosity, and its stability is affected by pH and ionic strength, thus impacting its application performance. Therefore, zinc plating using PAM gel polymer electrolyte electroplating solutions is only suitable for weakly acidic environments.
[0029] The above embodiments describe the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are only illustrative of the principles of the present invention. Various changes and modifications can be made to the present invention without departing from the scope of the principles of the present invention, and all such changes and modifications fall within the protection scope of the present invention.
Claims
1. A PAM gel polymer electrolyte electroplating solution for zinc electroplating, characterized in that: This electroplating solution is mainly a ternary system composed of a PAM polymer skeleton, metal salt, and liquid plasticizer. The PAM polymer skeleton is formed by polymerizing acrylamide monomers and forming a three-dimensional network structure through physical or chemical cross-linking. The metal salt is a soluble zinc salt, and the liquid plasticizer is a liquid electrolyte containing a soluble conductive salt. The pores of the three-dimensional network structure of the PAM polymer skeleton are filled with liquid plasticizer containing dissolved metal salt, ultimately forming a PAM gel polymer electrolyte electroplating solution for zinc electroplating. This electroplating solution has a jelly-like consistency and combines the characteristics of both liquid and solid electrolytes.
2. The PAM gel polymer electrolyte electroplating solution for zinc electroplating according to claim 1, characterized in that... The specific preparation process of the PAM polymer skeleton is as follows: First, acrylamide monomer and crosslinking agent methylenebisacrylamide are added to deionized water and stirred to form a mixed solution. Then, initiator ammonium persulfate and zinc chloride are added, stirred, and poured into a glass mold. The polymerization reaction is initiated under water bath conditions of 60~80℃ to obtain PAM hydrogel. The PAM hydrogel is soaked and washed with deionized water to remove ammonium persulfate, and then dried to obtain dry PAM hydrogel, i.e., PAM polymer skeleton.
3. The PAM gel polymer electrolyte electroplating solution for zinc electroplating according to claim 2, characterized in that: The mass ratio of acrylamide monomer to deionized water is 1:5; the amount of initiator added is 4wt%~6wt% of the mass of acrylamide monomer, and the mass ratio of ammonium persulfate to zinc chloride in the initiator is 1:1; the amount of crosslinking agent methylenebisacrylamide added is 0.01wt%~0.5wt% of the mass of acrylamide monomer.
4. The PAM gel polymer electrolyte electroplating solution for zinc electroplating according to claim 1, characterized in that: The metal salt is zinc chloride, and the content of the metal salt in the liquid plasticizer containing the dissolved metal salt is 60~90g / L, which is used to provide zinc ions required for electrodeposition.
5. The PAM gel polymer electrolyte electroplating solution for zinc electroplating according to claim 1, characterized in that: The liquid plasticizer is a liquid electrolyte containing conductive salt potassium chloride, wherein the content of conductive salt potassium chloride is 180~230g / L, which is used to improve the conductivity of the solution, improve the deep plating capability, and form a complex with Zn²⁺.
6. The PAM gel polymer electrolyte electroplating solution for zinc electroplating according to claim 1, characterized in that: The electroplating solution also contains a buffer, which is one or more of boric acid or hydrochloric acid. The buffer is dissolved in a liquid plasticizer and its concentration is 25~35g / L, which is used to stabilize the pH value of the electroplating solution in the optimal range of 4.6~5.
6.
7. The PAM gel polymer electrolyte electroplating solution for zinc electroplating according to claim 1, characterized in that: The electroplating solution also contains an additive, namely a zinc plating brightener, which is dissolved in a liquid plasticizer at a concentration of 10-20 mL / L. This brightener is used to obtain a core for a bright and fine coating and to increase cathodic polarization.
8. A zinc plating process based on the PAM gel polymer electrolyte plating solution according to any one of claims 1 to 7, characterized in that... The specific steps are as follows: Step S1: Perform pre-plating treatment on the workpiece, and then apply PAM gel polymer electrolyte plating solution to the surface of the workpiece. Step S2: Press the zinc metal sheet onto the outer surface of the other side of the PAM gel polymer electrolyte electroplating solution to form a structure of Zn + PAM electroplating solution for the plated part. Connect the anode of the power supply to the zinc metal sheet and the cathode to the plated part. Apply electricity to perform electroplating and complete the zinc electroplating operation. Remove the electrodes and PAM gel polymer electrolyte plating solution, and perform subsequent processing on the plated parts. The PAM gel polymer electrolyte plating solution can be reused. If the main components of the PAM gel polymer electrolyte plating solution have changed after use, the used PAM hydrogel electrolyte plating solution should be soaked again in a liquid plasticizer containing dissolved metal salts before reuse, so as to achieve repeated recycling of the PAM gel polymer electrolyte plating solution.
9. The galvanizing process according to claim 8, characterized in that... The specific process of pre-plating treatment of the workpiece in step S1 is as follows: chemical degreasing → hot water washing → hydrochloric acid solution pickling → cold water rinsing → running water rinsing → cold air drying.
10. The zinc plating process according to claim 8, characterized in that... The process parameters for the electroplating process in step S2 are set as follows: working temperature 20~30℃; current density controlled at 1~3A / dm²; and the thickness of the prepared PAM gel polymer electrolyte electroplating solution is 2~5mm.