Cyanide-free copper-zinc alloy plating solution and electroplating process

Abstract

The cyanide-free copper-zinc alloy plating solution comprises 18-24 g / L of polycuprous thiocyanate, 9-13 g / L of polyzinc thiocyanate, 130-170 g / L of polysodium thiocyanate and 8-12 mL / L of brightener, the pH value of the plating solution is 10-12, the temperature of a plating bath is 35-55 DEG C, the cathode current density is 0.5-1.5 A / dm < 2 >, the cathode movement speed is 3-5 m / min, a copper-zinc alloy plate with the copper mass fraction being 68% is used as an anode, and the anode movement speed is 3-5 m / min. The brightening agent is prepared from 60 to 100 parts of N, N '-di-n-propylethylenediamine, 10 to 20 parts of waterborne polyurethane resin, 80 to 120 parts of polyacrylamide of which the molecular weight is less than 8000 and 770 to 870 parts of deionized water. A steel matrix or zinc alloy matrix copper-zinc alloy and bright nickel plated sample piece is subjected to an acetate fog test for 72 h according to GB / T 10125-2021 Artificial Atmosphere Corrosion Test Salt Spray Test, the surface of the steel matrix or zinc alloy matrix copper-zinc alloy and bright nickel plated sample piece is free of rust, and according to GB / T 5270-2005 Metal Covering Layer Electro-Deposition and Chemical Deposition Layer Adhesive Strength Test Method, the coating binding force is tested by a thermal shock method. And the result meets the standard requirement.

Description

Technical Field

[0001] The invention belongs to the technical field of metal surface treatment, and in particular relates to a cyanide-free copper-zinc alloy plating solution and an electroplating process. Background Art

[0002] Cyanide copper plating has many excellent properties and has been widely used in electroplating production in the past. It is an indispensable copper plating process. Cyanide ions and cuprous ions have super strong complexing ability. The two form highly stable copper-cyanide complex ions, which significantly increase the deposition potential of cuprous ions. Therefore, the copper coating obtained by cyanide copper plating has strong bonding with the substrate and the coating is dense. [1] . The cyanide copper plating solution has good dispersibility and covering ability, and the plating solution is stable and easy to maintain. However, cyanide is extremely toxic. Countries around the world have successively issued bans on the use of cyanide. my country also issued relevant policies and decrees in 2003, requiring a comprehensive ban on cyanide electroplating. For many years, experts and scholars at home and abroad have been looking for a suitable cyanide-free copper plating process to replace cyanide copper plating. Although some results have been achieved, there are still deficiencies and shortcomings. Most of the existing cyanide-free copper plating processes have the problem of poor bonding between the coating and the substrate. Therefore, there is still a lot of work to be done to completely replace cyanide copper plating with cyanide-free copper plating. [2] To obtain a coating with good bonding strength, at least two key factors must be met. One is to prevent the base metal from undergoing a replacement reaction with the metal ions in the plating solution; the other is that the plating solution has a good activation ability for the base metal and can reduce the oxide film on the surface of the base.

[0003] The cyanide-free copper plating process mainly includes acid sulfate copper plating and cyanide-free alkaline copper plating. The main salts used in the mass-produced cyanide-free copper plating are all divalent copper salts, such as copper sulfate and copper pyrophosphate. Cyanide-free alkaline copper plating must use a ligand to generate ligands from copper ions. Commonly used ligands include hydroxyethylidene diphosphonic acid, pyrophosphate, citrate, ethylenediaminetetraacetic acid, etc. The ligands formed by these ligands and divalent copper ions cannot reach the polarization degree of cyanide ions to cuprous ions. These ligands all have the problem of replacement reaction with steel and zinc alloy base metals, and the configured plating solution also has the problem of insufficient activation ability for the base metal. Therefore, the divalent copper cyanide-free copper plating process developed by the industry for a long time has not achieved a breakthrough in solving the problem of bonding between the coating and the substrate. So far, many electroplating companies still have to use cyanide copper plating to prepare pre-plated copper layers on metal surfaces such as steel and zinc alloys.

[0004] References: [1] Ma Tao, Li Yungang, Yang Guiyu, et al., Research status of cyanide-free copper plating technology for steel substrates [J], Casting Technology, 2016, 37(12): 2579-2582. [2] Qin Zuzu, Li Jiansan, Xu Jinlai, Research progress of cyanide-free copper plating technology at home and abroad [J], Electroplating and Finishing, 2015, 34(3): 149-152. Summary of the invention

[0005] In order to solve the high pollution problem of preparing a pre-plated copper layer on a metal substrate using a cyanide copper plating process, the present invention provides a cyanide-free copper-zinc alloy plating solution and an electroplating process. In order to achieve the above purpose, the present invention adopts the following technical solutions: A cyanide-free copper-zinc alloy plating solution comprises the following components and contents: Polymeric cuprous thiocyanate 18-24 g / L, polymeric zinc thiocyanate 9-13 g / L, polymeric sodium thiocyanate 130-170 g / L, brightener 8-12 mL / L, plating solution pH 10-12; The brightener comprises the following components in weight fractions: 60-100 parts of N,N'-di-n-propylethylenediamine, 10-20 parts of waterborne polyurethane resin, 80-120 parts of polyacrylamide with a molecular weight less than 8000, and 770-870 parts of deionized water.

[0006] In some of the embodiments, the brightener is prepared as follows: 770 to 870 parts by weight of deionized water are added to a reaction tank, 60 to 100 parts of N,N'-di-n-propylethylenediamine, 10 to 20 parts of waterborne polyurethane resin, and 80 to 120 parts of polyacrylamide with a molecular weight of less than 8000 are added under stirring, and the brightener is obtained by stirring evenly.

[0007] In some embodiments, the preparation process of the cyanide-free copper-zinc alloy plating solution includes: (1) Add 1 / 2 deionized water into the plating tank; (2) According to the volume of the bath solution, add 130-170 g / L of polysodium thiocyanate to the plating tank while stirring, and stir until the added solids are completely dissolved; (3) According to the volume of the bath, add 18-24 g / L of polycuprous thiocyanate and 9-13 g / L of polyzinc thiocyanate to the plating tank while stirring, stir until the added solids are completely dissolved, and add water to the specified bath volume; (4) 0.1~0.5A / dm 2 The current is electrolyzed for 60 to 180 minutes; (5) Add 8-12 mL / L of brightener to the plating tank and stir evenly; (6) Add 10% by mass sulfuric acid or 10% by mass sodium hydroxide solution into the plating tank to adjust the pH of the plating solution to 10-12 to obtain the cyanide-free copper-zinc alloy plating solution.

[0008] A cyanide-free copper-zinc alloy electroplating process includes the following components and process parameters: Polymeric cuprous thiocyanate 18-24 g / L, polymeric zinc thiocyanate 9-13 g / L, polymeric sodium thiocyanate 130-170 g / L, brightener 8-12 mL / L, plating solution pH 10-12, plating tank temperature 35-55 °C, cathode current density 0.5-1.5 A / dm 2 The cathode moves at 3 to 5 m / min, and a copper-zinc alloy plate with a copper mass fraction of 68% is used as the anode, and the anode moving speed is 3 to 5 m / min.

[0009] In some of the embodiments, an anode moving method is used to avoid passivation of the anode surface, so that the copper and zinc on the anode plate are dissolved into the cyanide-free copper-zinc alloy plating solution.

[0010] In some embodiments, the area ratio of the anode to the cathode is (1-2):1.

[0011] In some of the embodiments, the mass fraction of copper in the prepared copper-zinc alloy coating is 58% to 78%.

[0012] The cyanide-free copper-zinc alloy electroplating process is adopted, and the metal substrate is pre-treated and then the cyanide-free copper-zinc alloy plating layer is directly prepared by the cyanide-free copper-zinc alloy electroplating process.

[0013] In some embodiments, the metal substrate is a steel substrate or a zinc alloy substrate.

[0014] In some of the embodiments, the metal substrate is an aluminum alloy substrate, and the aluminum alloy substrate is electrolessly zincated and then plated with a cyanide-free copper-zinc alloy.

[0015] Polymeric sodium thiocyanate can be reduced to generate negative divalent sulfide ions on the cathode, and the negative divalent sulfide ions can react with divalent copper ions on the anode surface to generate copper sulfide, resulting in passivation of the anode surface. Polymeric sodium thiocyanate also has a certain reducibility. After the anode surface is passivated, the polymerized sodium thiocyanate will be oxidized on the anode and lose its complexing ability. The present invention adopts anode movement and a larger anode area to avoid anode surface passivation, so that the anode is normally dissolved, thereby ensuring that the polymerized sodium thiocyanate is anodic oxidized.

[0016] In the traditional electroplating process, the process method of anode movement has not been seen.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. The cyanide-free copper-zinc alloy plating solution and electroplating process of the present invention adopts polysodium thiocyanate instead of traditional sodium cyanide as a complexing agent. The copper-zinc alloy plating solution and electroplating process are green and environmentally friendly, and comply with the national industrial development policy; 2. The cyanide-free copper-zinc alloy plating solution and electroplating process of the present invention are used to perform polymerized thiocyanate copper-zinc alloy plating on steel and zinc alloy substrates, and the bonding strength of the plating layer meets the requirements of GB / T 5270-2005 standard; 3. The cyanide-free copper-zinc alloy plating solution and electroplating process of the present invention are used to replace the traditional cyanide copper plating process to prepare the bottom plating layer, thus overcoming the high pollution problem of cyanide copper plating; 4. The cyanide-free copper-zinc alloy plating solution and electroplating process of the present invention improve the corrosion resistance of the coating by using the copper-zinc alloy coating as the coating, compared with the conventional cyanide copper plating to prepare the coating; 5. The cyanide-free copper-zinc alloy plating solution and electroplating process of the present invention adopts an anode moving method for plating, thus overcoming the defect that the anode surface is easily passivated. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings described herein are used to provide a further understanding of the present invention, constitute a part of the present application, and do not constitute an improper limitation of the present invention. In the drawings: Figure 1 1 is a schematic diagram of the coating structure of Example 1 of the present invention, which is a schematic diagram of cyanide-free copper-zinc alloy plating + bright nickel plating + rare earth electrolytic protection on the steel surface, in which 1 represents the steel substrate, 2 represents the copper-zinc alloy plating, 3 represents the bright nickel plating, and 4 represents the rare earth electrolytic protective film; Figure 2 The schematic diagram of the coating structure of Example 2 of the present invention is a schematic diagram of cyanide-free copper-zinc alloy plating + red copper plating on steel surface; 1 represents the steel substrate, 2 represents the copper-zinc alloy plating, and 3 represents the red copper plating; Figure 3 1 is a schematic diagram of the coating structure of Example 3 of the present invention; 1 is a schematic diagram of cyanide-free copper-zinc alloy plating + bright nickel plating + rare earth electrolytic protection on the surface of a zinc alloy die-casting, in which 1 represents a zinc alloy substrate, 2 represents a copper-zinc alloy plating, 3 represents a bright nickel plating, and 4 represents a rare earth electrolytic protective film; Figure 4 1 is a schematic diagram of the coating structure of Example 4 of the present invention, which is a schematic diagram of chemical zinc deposition + cyanide-free copper-zinc alloy plating on the surface of an aluminum alloy. In the figure, 1 represents an aluminum alloy substrate, 2 represents a chemical zinc deposition layer, and 3 represents a copper-zinc alloy coating. DETAILED DESCRIPTION

[0019] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments. The exemplary embodiments and descriptions of the present invention are used to explain the present invention but are not intended to limit the present invention.

[0020] A cyanide-free copper-zinc alloy plating solution and electroplating process include preparing a copper-zinc alloy electroplating additive, preparing a cyanide-free copper-zinc alloy plating solution, and plating the copper-zinc alloy.

[0021] 1. Preparation of copper-zinc alloy electroplating brightener: The brightener is prepared as follows: 770 to 870 parts by weight of deionized water are added to a reaction tank, 60 to 100 parts of N, N'-di-n-propylethylenediamine, 10 to 20 parts of waterborne polyurethane resin, and 80 to 120 parts of polyacrylamide with a molecular weight less than 8000 are added under stirring, and the brightener is obtained by stirring evenly.

[0022] Preferably, by weight, 770 to 870 parts of deionized water are added to a reaction tank, and 60 to 100 parts of N,N'-di-n-propylethylenediamine, 10 to 20 parts of waterborne polyurethane resin, and 80 to 120 parts of polyacrylamide with model GRO-70 are added under stirring, and stirred evenly to obtain the brightener.

[0023] Preferably, by weight, 770-870 parts of deionized water are added to a reaction tank, and 60-100 parts of N,N'-di-n-propylethylenediamine, 10-20 parts of waterborne polyurethane resin, and 80-120 parts of IC-113 polyacrylamide are added under stirring, and stirred evenly to obtain the brightener.

[0024] Preferably, by weight, 770-870 parts of deionized water are added to a reaction tank, and 60-100 parts of N,N'-di-n-propylethylenediamine, 10-20 parts of waterborne polyurethane resin, and 80-120 parts of IC-125 polyacrylamide are added under stirring, and stirred evenly to obtain the brightener.

[0025] Preferably, by weight, 770-870 parts of deionized water are added to a reaction tank, and 60-100 parts of N,N'-di-n-propylethylenediamine, 10-20 parts of waterborne polyurethane resin, and 80-120 parts of IC-213 polyacrylamide are added under stirring, and stirred evenly to obtain the brightener.

[0026] 2. Preparation of cyanide-free copper-zinc alloy plating solution: The preparation process of the cyanide-free copper-zinc alloy plating solution comprises: (1) Add 1 / 2 deionized water into the plating tank; (2) According to the volume of the bath solution, add 130-170 g / L of polysodium thiocyanate to the plating tank while stirring, and stir until the added solids are completely dissolved; (3) According to the volume of the bath, add 18-24 g / L of polycuprous thiocyanate and 9-13 g / L of polyzinc thiocyanate to the plating tank while stirring, stir until the added solids are completely dissolved, and add water to the specified bath volume; (4) 0.1~0.5A / dm 2 The current is electrolyzed for 60 to 180 minutes; (5) Add 8-12 mL / L of brightener to the plating tank and stir evenly; (6) Add 10% by mass sulfuric acid or 10% by mass sodium hydroxide solution into the plating tank to adjust the pH of the plating solution to 10-12 to obtain the cyanide-free copper-zinc alloy plating solution.

[0027] 3. Electroplating of cyanide-free copper-zinc alloy: The cyanide-free copper-zinc alloy electroplating process of the present invention is used for plating. Preferably, the cyanide-free copper-zinc alloy electroplating process includes the following components and process parameters: Polymeric cuprous thiocyanate 18-24 g / L, polymeric zinc thiocyanate 9-13 g / L, polymeric sodium thiocyanate 130-170 g / L, brightener 8-12 mL / L, plating solution pH 10-12, plating tank temperature 35-55 °C, cathode current density 0.5-1.5 A / dm 2 The cathode moves at 3 to 5 m / min, and a copper-zinc alloy plate with a copper mass fraction of 68% is used as the anode, and the anode moving speed is 3 to 5 m / min.

[0028] 1) A copper-zinc alloy coating, a bright nickel coating, and a rare earth electrolytic protective film are sequentially prepared on a steel substrate.

[0029] Preferably, the copper-zinc alloy coating has a thickness of 4 to 13 μm.

[0030] Preferably, the thickness of the bright nickel plating layer is 8 to 16 μm.

[0031] Preferably, the bright nickel plating layer is prepared by using the NINFEA 8003 bright nickel plating process of Chaobang Chemical: Nickel sulfate hexahydrate 240-320g / L, nickel chloride hexahydrate 45-70g / L, boric acid 40-50g / L, NINFEASC-260 light nickel softener 15-40mL / L, NINFEA AS-250 light nickel auxiliary 3-7mL / L, NINFEA 8003 light nickel main brightener 0.4-0.8mL / L, NINFEA NI-35 light nickel wetting agent 0.5-1.5mL / L, plating solution pH 4.2-4.8, plating tank temperature 55-65℃, cathode current density 3-6A / dm 2 , uniform air stirring.

[0032] Preferably, the rare earth electrolytic protection film is prepared by the rare earth electrolytic protection process developed by Chaobang Chemical: Cerium chloride 1-5g / L, HEDP complexing agent 5-30g / L, sodium molybdate 5-10g / L, anhydrous sodium carbonate 100-150g / L, bath pH 11.5-12.5, cathode current density 0.5-1.5A / dm 2 , operate at room temperature, use the plated part as cathode and the titanium plate as anode, and electrolyze for 60 to 120 seconds.

[0033] 2) A copper-zinc alloy coating and a red copper coating are sequentially prepared on a steel substrate.

[0034] Preferably, the copper-zinc alloy coating has a thickness of 4 to 13 μm.

[0035] Preferably, the thickness of the red copper plating layer is 10 to 20 μm.

[0036] Preferably, the red copper plating layer is prepared by using the GAFFA M-8000 acid bright copper plating process of Chaobang Chemical: Copper sulfate pentahydrate 170-220 g / L, sulfuric acid 50-90 g / L, chloride ion 30-120 mg / L, GAFFA M-8000Mu tank opener 3-8 mL / L, GAFFA M-8000 A main light agent 0.3-0.6 mL / L, GAFFA M-8000 B auxiliary light agent 0.05-0.3 mL / L, plating tank temperature 18-35 ° C, cathode current density 2-6 A / dm 2 , anode current density 0.5~3A / dm 2 , using strong and uniform air stirring.

[0037] 3) Prepare copper-zinc alloy coating, bright nickel coating and rare earth electrolytic protective coating on zinc alloy die castings.

[0038] Preferably, the copper-zinc alloy coating has a thickness of 4 to 13 μm.

[0039] Preferably, the thickness of the bright nickel plating layer is 8 to 16 μm.

[0040] Preferably, the bright nickel plating layer is prepared by using the NINFEA 300 bright nickel plating process of Chaobang Chemical: Nickel sulfate hexahydrate 240-300g / L, nickel chloride hexahydrate 50-70g / L, boric acid 40-50g / L, NINFEASC-230 auxiliary agent 12-20mL / L, NINFEA 300 main brightener 0.5-1.5mL / L, NINFEA 302 filler 0.5-1.5mL / L, NINFEA NI-35 bright nickel wetting agent 0.5-1.5mL / L, plating solution pH 4.0-4.5, plating tank temperature 55-65℃, cathode current density 2-6A / dm 2 , anode current density 1~4A / dm 2 , uniform air stirring.

[0041] Preferably, the rare earth electrolytic protection film is prepared by the rare earth electrolytic protection process developed by Chaobang Chemical: Cerium acetate 1-5g / L, HEDP complexing agent 5-30g / L, sodium molybdate 5-10g / L, anhydrous sodium carbonate 100-150g / L, bath pH 11.5-12.5, cathode current density 0.5-1.5A / dm 2 , operate at room temperature, use the plated part as cathode and the titanium plate as anode, and electrolyze for 60 to 120 seconds.

[0042] 4) Prepare chemical zinc deposition layer and copper-zinc alloy plating layer on aluminum alloy parts.

[0043] Preferably, the copper-zinc alloy coating has a thickness of 10 to 25 μm.

[0044] Preferably, the chemical zinc deposition layer is prepared using AZIN-113 acidic aluminum zinc deposition agent produced by Chaobang Chemical: AZIN-113 acidic aluminum zinc precipitation agent 150 ~ 250mL / L, working temperature 15 ℃ ~ 30 ℃, bath pH value 3.4 ~ 4.5, zinc precipitation time 30 ~ 90s.

[0045] Embodiment 1: A cyanide-free copper-zinc alloy plating solution and electroplating process comprises the steps of preparing a copper-zinc alloy electroplating additive, preparing a cyanide-free copper-zinc alloy plating solution, and sequentially performing cyanide-free copper-zinc alloy plating, bright nickel plating, and rare earth electrolytic protection on a steel substrate.

[0046] 1. Preparation of copper-zinc alloy electroplating additives: Calculated by weight, 820 parts of deionized water were added to a reaction tank, and 80 parts of N,N'-di-n-propylethylenediamine, 15 parts of waterborne polyurethane resin, and 100 parts of polyacrylamide with model GRO-70 were added under stirring, and stirred evenly to obtain the brightener.

[0047] 2. Preparation of cyanide-free copper-zinc alloy plating solution: The preparation process of the cyanide-free copper-zinc alloy plating solution comprises: (1) Add 1 / 2 deionized water into the plating tank; (2) According to the volume of the bath solution, add 150 g / L of polysodium thiocyanate to the plating tank while stirring, and stir until the added solid is completely dissolved; (3) According to the volume of the bath, add 21 g / L of polycuprous thiocyanate and 11 g / L of polyzinc thiocyanate to the plating tank while stirring, stir until the added solids are completely dissolved, and add water to the specified bath volume; (4) At 0.3A / dm 2 The current was electrolyzed for 120 min; (5) Add 10 mL / L of brightener to the plating tank and stir evenly; (6) adding 10% by mass sulfuric acid or 10% by mass sodium hydroxide solution into the plating tank to adjust the pH of the plating solution to 10.5, thereby obtaining the cyanide-free copper-zinc alloy plating solution.

[0048] 3. Electroplating: like Figure 1 As shown, a cyanide-free copper-zinc alloy coating 2, a bright nickel coating 3, and a rare earth electrolytic protective coating 4 are sequentially prepared on a steel substrate 1 from the inside to the outside.

[0049] 1) Pre-treatment: The steel substrate 1 is subjected to the current pre-treatment process of "alkaline chemical degreasing → water washing → acid washing → water washing → alkaline cathode electrolytic degreasing → water washing → alkaline anode electrolytic degreasing → water washing → activation → water washing".

[0050] 2) Cyanide-free copper-zinc alloy plating: The cyanide-free copper-zinc alloy electroplating process of the present invention is adopted to prepare a cyanide-free copper-zinc alloy coating 2, and the coating thickness is 8 μm.

[0051] Polymeric cuprous thiocyanate 21g / L, polymeric zinc thiocyanate 11g / L, polymeric sodium thiocyanate 150g / L, brightener 10mL / L, plating solution pH 10.5, plating tank temperature 45℃, cathode current density 1.0A / dm 2 , the cathode moves at 4m / min, a copper-zinc alloy plate with a copper mass fraction of 68% is used as the anode, and the anode moving speed is 4m / min.

[0052] 3) Bright nickel plating: The bright nickel plating layer 3 was prepared by using the NINFEA 8003 bright nickel plating process of Chaobang Chemical, and the plating thickness was 15 μm.

[0053] Nickel sulfate hexahydrate 300g / L, nickel chloride hexahydrate 60g / L, boric acid 48g / L, NINFEA SC-260 nickel softener 28mL / L, NINFEA AS-250 nickel auxiliary 5mL / L, NINFEA 8003 nickel main brightener 0.6mL / L, NINFEA NI-35 nickel wetting agent 1.0mL / L, plating solution pH 4.5, plating tank temperature 58℃, cathode current density 4A / dm 2 , uniform air stirring.

[0054] 4) Rare earth electrolysis protection: The rare earth electrolytic protection membrane 4 was prepared using the rare earth electrolytic protection process developed by Chaobang Chemical.

[0055] Cerium chloride 3g / L, HEDP complexing agent 20g / L, sodium molybdate 10g / L, anhydrous sodium carbonate 120g / L, bath pH 12, cathode current density 1A / dm 2 , operated at room temperature, using the plated piece as cathode and the titanium plate as anode, and electrolysis for 100s. Example

[0056] A cyanide-free copper-zinc alloy plating solution and electroplating process comprises the steps of preparing a copper-zinc alloy electroplating additive, preparing a cyanide-free copper-zinc alloy plating solution, and sequentially performing cyanide-free copper-zinc alloy plating and red copper plating on a steel substrate.

[0057] 1. Preparation of copper-zinc alloy electroplating additives: Calculated by weight, 820 parts of deionized water were added to a reaction tank, and 80 parts of N,N'-di-n-propylethylenediamine, 15 parts of waterborne polyurethane resin, and 100 parts of IC-113 polyacrylamide were added under stirring, and stirred evenly to obtain the brightener.

[0058] 2. Preparation of cyanide-free copper-zinc alloy plating solution: The preparation process of the cyanide-free copper-zinc alloy plating solution comprises: (1) Add 1 / 2 deionized water into the plating tank; (2) According to the volume of the bath solution, add 170 g / L of polysodium thiocyanate to the plating tank while stirring, and stir until the added solid is completely dissolved; (3) According to the volume of the bath, add 24 g / L of polycuprous thiocyanate and 13 g / L of polyzinc thiocyanate to the plating tank while stirring, stir until the added solids are completely dissolved, and add water to the specified bath volume; (4) At 0.5A / dm 2 The current was electrolyzed for 80 min; (5) Add 10 mL / L of brightener to the plating tank and stir evenly; (6) adding 10% by mass sulfuric acid or 10% by mass sodium hydroxide solution into the plating tank to adjust the pH of the plating solution to 11.5, thereby obtaining the cyanide-free copper-zinc alloy plating solution.

[0059] 3. Electroplating: like Figure 2 As shown, a cyanide-free copper-zinc alloy coating 2 and a red copper coating 3 are sequentially prepared on a steel substrate 1 from the inside to the outside.

[0060] 1) Pre-treatment: The steel substrate 1 is subjected to the current pre-treatment process of "alkaline chemical degreasing → water washing → acid washing → water washing → alkaline cathode electrolytic degreasing → water washing → alkaline anode electrolytic degreasing → water washing → activation → water washing".

[0061] 2) Cyanide-free copper-zinc alloy plating: The cyanide-free copper-zinc alloy electroplating process of the present invention is adopted to prepare a cyanide-free copper-zinc alloy coating 2, and the coating thickness is 8 μm.

[0062] Polymeric cuprous thiocyanate 24g / L, polymeric zinc thiocyanate 13g / L, polymeric sodium thiocyanate 170g / L, brightener 10mL / L, plating solution pH 11.5, plating tank temperature 35℃, cathode current density 1.0A / dm 2 , the cathode moves at 4m / min, a copper-zinc alloy plate with a copper mass fraction of 68% is used as the anode, and the anode moving speed is 4m / min.

[0063] 3) Red copper plating: The red copper coating 3 was prepared by using GAFFA M-8000 acid bright copper plating process of Chaobang Chemical, and the coating thickness was 15 μm.

[0064] Copper sulfate pentahydrate 200g / L, sulfuric acid 70g / L, chloride ion 80mg / L, GAFFA M-8000 Mu tank opener 5.5mL / L, GAFFA M-8000 A main light agent 0.5mL / L, GAFFA M-8000 B auxiliary light agent 0.2mL / L, plating tank temperature 25℃, cathode current density 4A / dm 2 , anode current density 2A / dm 2 , using strong and uniform air stirring. Example

[0065] A cyanide-free copper-zinc alloy plating solution and electroplating process comprises the steps of preparing a copper-zinc alloy electroplating additive, preparing a cyanide-free copper-zinc alloy plating solution, and sequentially performing cyanide-free copper-zinc alloy plating, bright nickel plating, and rare earth electrolytic protection on a zinc alloy die-casting substrate.

[0066] 1. Preparation of copper-zinc alloy electroplating additives: Calculated by weight, 820 parts of deionized water were added to a reaction tank, and 80 parts of N,N'-di-n-propylethylenediamine, 15 parts of waterborne polyurethane resin, and 100 parts of IC-125 polyacrylamide were added under stirring, and stirred evenly to obtain the brightener.

[0067] 2. Preparation of cyanide-free copper-zinc alloy plating solution: The preparation process of the cyanide-free copper-zinc alloy plating solution comprises: (1) Add 1 / 2 deionized water into the plating tank; (2) According to the volume of the bath solution, add 140 g / L of polysodium thiocyanate to the plating tank while stirring, and stir until the added solid is completely dissolved; (3) According to the volume of the bath, add 20 g / L of polycuprous thiocyanate and 10 g / L of polyzinc thiocyanate to the plating tank while stirring, stir until the added solids are completely dissolved, and add water to the specified bath volume; (4) At 0.2A / dm 2 The current was electrolyzed for 150 min; (5) Add 10 mL / L of brightener to the plating tank and stir evenly; (6) adding 10% by mass sulfuric acid or 10% by mass sodium hydroxide solution into the plating tank to adjust the pH of the plating solution to 11, thereby obtaining the cyanide-free copper-zinc alloy plating solution.

[0068] 3. Electroplating: like Figure 3 As shown, a cyanide-free copper-zinc alloy coating 2, a bright nickel coating 3, and a rare earth electrolytic protective coating 4 are sequentially prepared on a zinc alloy die-casting substrate 1 from the inside to the outside.

[0069] 1) Pre-treatment: The zinc alloy die casting substrate 1 is subjected to "chemical wax removal → water washing → ultrasonic wax removal → water washing → ultrasonic oil removal → water washing → acid salt activation → water washing" by using the existing pre-treatment process.

[0070] 2) Cyanide-free copper-zinc alloy plating: The cyanide-free copper-zinc alloy electroplating process of the present invention is adopted to prepare a cyanide-free copper-zinc alloy coating 2, and the coating thickness is 8 μm.

[0071] Polymerized cuprous thiocyanate 20g / L, polyzinc thiocyanate 10g / L, polysodium thiocyanate 140g / L, brightener 10mL / L, plating solution pH 11, plating tank temperature 55℃, cathode current density 1.0A / dm 2 , the cathode moves at 4m / min, a copper-zinc alloy plate with a copper mass fraction of 68% is used as the anode, and the anode moving speed is 4m / min.

[0072] 3) Bright nickel plating: The bright nickel coating 3 was prepared by using the NINFEA 300 bright nickel plating process of Chaobang Chemical, and the coating thickness was 15 μm.

[0073] Nickel sulfate hexahydrate 280g / L, nickel chloride hexahydrate 65g / L, boric acid 48g / L, NINFEA SC-230 auxiliary agent 16mL / L, NINFEA 300 main brightener 1.0mL / L, NINFEA 302 filler 1.0mL / L, NINFEA NI-35 bright nickel wetting agent 1.0mL / L, plating solution pH 4.2, temperature 58℃, cathode current density 4A / dm 2 , anode current density 3A / dm 2 , uniform air stirring.

[0074] 4) Rare earth electrolysis protection: The rare earth electrolytic protection membrane 4 was prepared using the rare earth electrolytic protection process developed by Chaobang Chemical.

[0075] Cerium acetate 3g / L, HEDP complexing agent 20g / L, sodium molybdate 10g / L, anhydrous sodium carbonate 120g / L, bath pH 12, cathode current density 1A / dm 2 , operated at room temperature, using the plated piece as cathode and the titanium plate as anode, and electrolysis for 100s.

[0076] Embodiment 4: A cyanide-free copper-zinc alloy plating solution and electroplating process comprises the steps of preparing a copper-zinc alloy electroplating additive, preparing a cyanide-free copper-zinc alloy plating solution, and sequentially performing chemical zinc deposition and cyanide-free copper-zinc alloy plating on an aluminum alloy substrate.

[0077] 1. Preparation of copper-zinc alloy electroplating additives: Calculated by weight, 820 parts of deionized water were added to a reaction tank, and 80 parts of N,N'-di-n-propylethylenediamine, 15 parts of waterborne polyurethane resin, and 100 parts of IC-213 polyacrylamide were added under stirring, and stirred evenly to obtain the brightener.

[0078] 2. Preparation of cyanide-free copper-zinc alloy plating solution: The preparation process of the cyanide-free copper-zinc alloy plating solution comprises: (1) Add 1 / 2 deionized water into the plating tank; (2) According to the volume of the bath solution, add 130 g / L of polysodium thiocyanate to the plating tank while stirring, and stir until the added solid is completely dissolved; (3) According to the volume of the bath, add 18 g / L of polycuprous thiocyanate and 9 g / L of polyzinc thiocyanate to the plating tank while stirring, stir until the added solids are completely dissolved, and add water to the specified bath volume; (4) At 0.4A / dm 2The current was electrolyzed for 90 minutes; (5) Add 10 mL / L of brightener to the plating tank and stir evenly; (6) adding 10% by mass sulfuric acid or 10% by mass sodium hydroxide solution into the plating tank to adjust the pH of the plating solution to 10, thereby obtaining the cyanide-free copper-zinc alloy plating solution.

[0079] 3. Electroplating of cyanide-free copper-zinc alloy: like Figure 4 As shown, a chemical zinc deposition layer 2 and a cyanide-free copper-zinc alloy coating 3 are sequentially prepared on an aluminum alloy substrate 1 from the inside to the outside.

[0080] 1) Pre-treatment: The aluminum alloy substrate 1 is subjected to "chemical degreasing → water washing → ultrasonic degreasing → water washing → film removal → water washing → light emitting → water washing → weak corrosion → water washing" by using the current pre-treatment process.

[0081] 2) Chemical zinc deposition: The chemical zinc deposition layer 2 was prepared using AZIN-113 acidic aluminum zinc deposition agent produced by Chaobang Chemical.

[0082] AZIN-113 acidic aluminum zinc precipitation agent 200mL / L, working temperature 25℃, bath pH 4.0, zinc precipitation time 60s.

[0083] The specific process is: "first zinc precipitation → water washing → zinc stripping → water washing → second zinc precipitation → water washing".

[0084] 3) Cyanide-free copper-zinc alloy plating: The cyanide-free copper-zinc alloy electroplating process of the present invention is adopted to prepare a cyanide-free copper-zinc alloy coating 3, and the coating thickness is 18 μm.

[0085] Polymeric cuprous thiocyanate 18g / L, polymeric zinc thiocyanate 9g / L, polymeric sodium thiocyanate 130g / L, brightener 10mL / L, plating solution pH 10, plating tank temperature 45℃, cathode current density 0.8A / dm 2 , the cathode moves at 4m / min, a copper-zinc alloy plate with a copper mass fraction of 68% is used as the anode, and the anode moving speed is 4m / min.

[0086] Test Example 1: The effect of the concentration change of N,N'-di-n-propylethylenediamine in the brightener of the present invention on the coating was tested.

[0087] Polymeric cuprous thiocyanate 20g / L, polymeric zinc thiocyanate 11g / L, polymeric sodium thiocyanate 145g / L, plating solution pH 11, plating tank temperature 45°C, cathode current density 1.0A / dm 2, using copper-zinc alloy plate as anode. The content of waterborne polyurethane and GRO-70 polyacrylamide in the brightener takes the middle value of the brightener formula, and the amount of N,N'-di-n-propylethylenediamine added to the plating solution is 0.2-1.4g / L. The test shows that the range of the amount of N,N'-di-n-propylethylenediamine added is not wide. The test results show that the concentration of N,N'-di-n-propylethylenediamine in the brightener is calculated according to the upper and lower limits, and the amount of the brightener added in the range of 7-13mL / L can usually obtain a good copper-zinc alloy coating.

[0088] Table 1, Effect of the amount of N,N'-di-n-propylethylenediamine added on the quality of the coating Test Example 2: The influence of the concentration change of the waterborne polyurethane resin in the brightener of the present invention on the coating was tested.

[0089] Polymeric cuprous thiocyanate 20g / L, polymeric zinc thiocyanate 11g / L, polymeric sodium thiocyanate 145g / L, plating solution pH 11, plating tank temperature 45°C, cathode current density 1.0A / dm 2 , using copper-zinc alloy plate as anode. The addition amount of N,N'-di-n-propylethylenediamine and GRO-70 polyacrylamide is the middle value of the formula, and the addition amount of waterborne polyurethane resin in the plating solution is 0.01-0.40g / L. The test shows that the concentration of waterborne polyurethane resin in the brightener is calculated according to the upper and lower limits, and the addition amount of the brightener in the range of 5-17mL / L can obtain a good copper-zinc alloy coating.

[0090] Table 2, Effect of the amount of waterborne polyurethane resin added on the quality of the coating Table 2, Effect of the amount of waterborne polyurethane resin added on the quality of the coating Test Example 3: The influence of the concentration change of polyacrylamide with a molecular weight less than 8000 in the brightener of the present invention on the coating was tested.

[0091] Polymeric cuprous thiocyanate 20g / L, polymeric zinc thiocyanate 11g / L, polymeric sodium thiocyanate 145g / L, plating solution pH 11, plating tank temperature 45°C, cathode current density 1.0A / dm 2 , using copper-zinc alloy plate as anode. The amount of waterborne polyurethane and N,N'-di-n-propylethylenediamine added to the plating solution is the middle value of the formula, and the amount of GRO-70 polyacrylamide added to the plating solution is 0.2-2.0g / L. The test shows that the range of the amount of GRO-70 polyacrylamide added is relatively wide. According to the upper and lower limits of the concentration of polyacrylamide with a molecular weight of less than 8000 in the brightener, the amount of the brightener added in the range of 5-17mL / L can obtain a good copper-zinc alloy coating.

[0092] Table 3, Effect of GRO-70 polyacrylamide addition on coating quality Table 3, Effect of GRO-70 polyacrylamide addition on coating quality The comprehensive test results of Test Examples 1-3 show that, based on the upper and lower limits of the concentration of the components contained in the brightener, a good copper-zinc alloy coating can usually be obtained when the addition amount of the brightener is within the range of 7 to 13 mL / L.

[0093] Test example 4: A 50mm×100mm×3mm steel test piece was plated with copper-zinc alloy, bright nickel, and rare earth electrolytic protection according to this process. The thickness of the copper-zinc alloy coating was 8μm, and the bright nickel coating was 15μm. According to GB / T 10125-2021 "Artificial atmosphere corrosion test salt spray test" standard, the acetic acid salt spray test was carried out for 72 hours, and there was no red rust on the surface of the sample.

[0094] Test Example 5: A 50mm×100mm×3mm steel test piece was cyanide-plated with copper, bright nickel, and rare earth electrolytic protection according to the traditional process. The thickness of the copper plating layer was 8μm and the bright nickel plating layer was 16μm. After 60 hours of acetic acid salt spray test according to GB / T 10125-2021 "Artificial atmosphere corrosion test salt spray test" standard, red rust spots began to appear on the surface of the sample. Comparing Test Example 4 with Test Example 5, it can be seen that the corrosion resistance of the base layer using cyanide-free copper-zinc alloy is higher than that of the base layer using cyanide copper plating.

[0095] Test Example 6: The cyanide-free copper-zinc alloy + bright nickel-plated steel surface samples prepared in Example 1 and the cyanide-free copper-zinc alloy + red copper-plated steel surface samples prepared in Example 2 were tested for coating adhesion in accordance with GB / T 5270-2005 "Review of test methods for adhesion strength of electrodeposited and chemically deposited metal coatings on metal substrates". The plated parts were placed in a heating furnace and heated to 300°C for 60 minutes. After being taken out, they were quenched in water at room temperature. There was no blistering or shedding of the coating, and the coating adhesion met the standard requirements.

[0096] Test Example 7: The zinc alloy die-casting prepared in Example 3 was plated with copper-zinc alloy and bright nickel on its surface without cyanide. The coating adhesion was tested in accordance with GB / T5270-2005 "Review of test methods for adhesion strength of electrodeposited and chemically deposited metal coatings on metal substrates". The plated part was heated to 150°C in a heating furnace and kept warm for 60 minutes. After being taken out, it was quenched in water at room temperature. There was no blistering or shedding of the coating, and the coating adhesion met the standard requirements.

[0097] Test Example 8: The aluminum alloy pressed surface chemical zinc deposition + cyanide-free copper-zinc alloy sample prepared in Example 4 was tested for coating adhesion in accordance with GB / T 5270-2005 "Review of test methods for adhesion strength of electrodeposited and chemically deposited metal coatings on metal substrates". The plated part was placed in a heating furnace and heated to 220°C for 60 minutes. After being taken out, it was quenched in water at room temperature. There was no blistering or shedding of the coating, and the coating adhesion met the standard requirements.

[0098] The technical solutions provided by the embodiments of the present invention are described in detail above. The principles and implementation methods of the embodiments of the present invention are described in detail using specific examples herein. The description of the embodiments above is only applicable to help understand the principles of the embodiments of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A cyanide-free copper-zinc alloy plating solution, characterized in that: Contains the following ingredients and contents: Polymeric cuprous thiocyanate 18-24 g / L, polymeric zinc thiocyanate 9-13 g / L, polymeric sodium thiocyanate 130-170 g / L, brightener 8-12 g / L, plating solution pH 10-12; The brightener comprises the following components in weight fractions: 60-100 parts of N,N'-di-n-propylethylenediamine, 10-20 parts of waterborne polyurethane resin, 80-120 parts of polyacrylamide with a molecular weight less than 8000, and 770-870 parts of deionized water.

2. The cyanide-free copper-zinc alloy plating solution according to claim 1, characterized in that The brightener is prepared as follows: Calculated by weight, 770-870 parts of deionized water are added to a reaction tank, and 60-100 parts of N,N'-di-n-propylethylenediamine, 10-20 parts of waterborne polyurethane resin, and 80-120 parts of polyacrylamide with a molecular weight less than 8000 are added under stirring, and stirred evenly to obtain the brightener.

3. The cyanide-free copper-zinc alloy plating solution according to claim 1, characterized in that The preparation process of the cyanide-free copper-zinc alloy plating solution comprises: (1) Add 1 / 2 deionized water into the plating tank; (2) According to the volume of the bath solution, add 130-170 g / L of polysodium thiocyanate to the plating tank while stirring, and stir until the added solids are completely dissolved; (3) According to the volume of the bath, add 18-24 g / L of polycuprous thiocyanate and 9-13 g / L of polyzinc thiocyanate to the plating tank while stirring, stir until the added solids are completely dissolved, and add water to the specified bath volume; (4) 0.1~0.5A / dm 2 The current is electrolyzed for 60 to 180 minutes; (5) Add 8-12 mL / L of brightener to the plating tank and stir evenly; (6) Add 10% by mass sulfuric acid or 10% by mass sodium hydroxide solution into the plating tank to adjust the pH of the plating solution to 10-12 to obtain the cyanide-free copper-zinc alloy plating solution.

4. A cyanide-free copper-zinc alloy electroplating process, characterized in that: Including the following ingredients and process parameters: Polymeric cuprous thiocyanate 18-24 g / L, polymeric zinc thiocyanate 9-13 g / L, polymeric sodium thiocyanate 130-170 g / L, brightener 8-12 mL / L, plating solution pH 10-12, plating tank temperature 35-55 °C, cathode current density 0.5-1.5 A / dm 2 The cathode moves at 3 to 5 m / min, and a copper-zinc alloy plate with a copper mass fraction of 68% is used as the anode, and the anode moving speed is 3 to 5 m / min.

5. The cyanide-free copper-zinc alloy electroplating process according to claim 4, characterized in that: The anode moving method is adopted to avoid the passivation of the anode surface, so that the copper and zinc on the anode plate are dissolved into the cyanide-free copper-zinc alloy plating solution.

6. The cyanide-free copper-zinc alloy electroplating process according to claim 4, characterized in that: The area ratio of the anode to the cathode is (1-2):

1.

7. The cyanide-free copper-zinc alloy electroplating process according to claim 4, characterized in that: The mass fraction of copper in the prepared copper-zinc alloy coating is 58% to 78%.

8. The cyanide-free copper-zinc alloy electroplating process according to claim 4 is characterized in that: After the metal substrate is pre-treated, the cyanide-free copper-zinc alloy electroplating process is used to directly prepare the cyanide-free copper-zinc alloy coating.

9. The cyanide-free copper-zinc alloy electroplating process according to claim 8, characterized in that: The metal matrix is ​​a steel matrix or a zinc alloy matrix.

10. The cyanide-free copper-zinc alloy electroplating process according to claim 8, characterized in that: The metal substrate is an aluminum alloy substrate, and the aluminum alloy substrate is plated with a cyanide-free copper-zinc alloy after chemical zinc deposition.

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