Cyanide-free cadmium plating leveling agent and cadmium plating process

Abstract

The invention discloses a cyanide-free cadmium plating leveling agent and a cadmium plating process. The leveling agent is prepared from 5 g / L to 10 g / L of trimercapto-s-triazine, 30 g / L to 60 g / L of organic amine epoxy derivatives and 5 g / L to 10 g / L of sodium hydroxide. According to the cadmium plating process, 25-35 g / L of cadmium chloride, 100-140 g / L of potassium chloride, 1.5-2.5 mL / L of a leveling agent, 100-140 g / L of a coordination agent, 25-30 mL / L of an auxiliary agent and 1.5-2.5 mL / L of a brightening agent are adopted, the temperature of a plating tank is 20-35 DEG C, the pH value of a plating solution is 7-9, the cathode current density is 1.0-2.5 A / dm < 2 >, the cathode movement speed is 2-4 m / min, and the anode current density is 0.3-1.0 A / dm < 2 >. Tests show that after the leveling agent is added into the cyanide-free cadmium plating solution, the flatness of a cadmium plating layer is obviously improved, and the consumption of the brightening agent is obviously reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of metal surface treatment, and in particular relates to a cyanide-free cadmium plating leveler and a cadmium plating process. Background Art

[0002] In 2014, Chaobang Chemical launched a research project to develop a potassium chloride cyanide-free cadmium plating process. [1-3] Since 2015, this technology has been put into large-scale production in companies such as Aerospace Precision, Huafeng Electric, and AVIC Liyuan, achieving good economic and social benefits. [2-4] .

[0003] In 2016, Chaobang Chemical applied for the national invention patent "Acidic Cyanide-free Cadmium Plating Additives, Plating Solution Preparation and Electroplating Process", with the authorization announcement number CN 106245071 B. The patent discloses the process formula of complexing agent, brightener and auxiliary agent in the potassium chloride cyanide-free cadmium plating process. The process currently put into mass production is called PULIZIER NCC-617 Potassium Chloride Cyanide-free Cadmium Plating Process, and its composition and process parameters are: cadmium chloride 25-35g / L, potassium chloride 100-140g / L, PULIZIER NCC-617 AC complexing agent 100-140g / L, PULIZIER NCC-617 Base auxiliary agent 25-30mL / L, PULIZIER NCC-617 Bri brightener 1.5-2.5mL / L, plating tank temperature 20-35℃, plating solution pH 7-9, cathode current density 0.5-1.5A / dm 2 , cathode movement 2~4m / min, anode current density 1.0~2.5A / dm 2 .

[0004] During the production process, it was found that the developed potassium chloride cyanide-free cadmium plating process had the following two problems: first, the consumption of cadmium plating brightener was large, and the decomposition products of the brightener accumulated in the plating solution, resulting in the passivation of the military green coating and the appearance of flowery phenomenon; second, after the plating solution has been used for a certain period of time, the coating becomes rough, and it is necessary to increase the amount of brightener added to improve the coating quality.

[0005] References: [1]. Guo Chongwu, Research and development of a new type of acidic cyanide-free cadmium plating process [J], Electroplating and Finishing, 2016, 35(5): 250-255. [2]. Dai Pengmin, Tang Qi, Research and application of a new type of cyanide-free cadmium plating process [J], Electroplating and Finishing, 2017, 39(2): 35-38. [3]. Chen Jianrui, Guo Chongwu, Application of cyanide-free acidic cadmium plating on aerospace parts [J], Electroplating and Finishing, 2017, 39(3): 23-24+28. [4] Lai Huanwen, Guo Chongwu, Chen Mei, et al., Preparation of ultra-high corrosion resistance potassium chloride cadmium plating protective layer [J], Electroplating and Finishing, 2021, 40(3): 1762-1766. Summary of the invention

[0006] In order to solve the problems of plating solution and coating quality in potassium chloride cyanide-free cadmium plating process, the present invention provides a cyanide-free cadmium plating leveler and cadmium plating process. In order to achieve the above purpose, the present invention adopts the following technical scheme: A cyanide-free cadmium plating leveler, comprising the following ingredients and contents: Trimercapto-s-triazine 5-10 g / L, organic amine epoxy derivative 30-60 g / L, sodium hydroxide 5-10 g / L.

[0007] In some embodiments, the cyanide-free cadmium plating leveler is prepared as follows: Add 50 kg of deionized water and 0.5-1 kg of sodium hydroxide into the reaction tank, stir evenly, add 0.5-1 kg of trimercapto-s-triazine, stir until the solid is completely dissolved, then add 3-6 kg of organic amine epoxy derivatives, add water to 100 L, stir evenly to obtain the cyanide-free cadmium plating leveler.

[0008] In some embodiments, the organic amine epoxy derivative is an organic amine epoxy derivative with a product model of GDX.

[0009] In some embodiments, the amount of the cyanide-free cadmium plating leveler added to the cyanide-free cadmium plating solution is 1.5-2.5 mL / L.

[0010] In some embodiments, the cyanide-free cadmium plating leveler is applied to the existing cyanide-free cadmium plating solution.

[0011] In some embodiments, the cyanide-free cadmium plating leveler is applied to a potassium chloride cyanide-free cadmium plating solution.

[0012] A cyanide-free cadmium plating process includes the following components, contents, and process parameters: Cadmium chloride 25-35 g / L, potassium chloride 100-140 g / L, cyanide-free cadmium plating leveler 1.5-2.5 mL / L, PULIZIER NCC-617 AC complexing agent 100-140 g / L, PULIZIER NCC-617 Base auxiliary agent 25-30 mL / L, PULIZIER NCC-617 Bri brightener 1.5-2.5 mL / L, plating tank temperature 20-35 ° C, plating solution pH 7-9, cathode current density 0.5-1.5 A / dm 2 , cathode movement 2~4m / min, anode current density 1.0~2.5A / dm 2 The anode is made of cadmium plate with a mass fraction of 99.97%.

[0013] In some of the embodiments, the cadmium plating process is used to prepare a cyanide-free cadmium plating layer on a steel substrate or an aluminum alloy substrate.

[0014] In some of the embodiments, a cyanide-free cadmium plating layer is prepared on an aluminum alloy substrate, and a chemical zinc deposition layer and a cyanide-free copper-zinc alloy plating layer are further included between the aluminum alloy substrate and the cadmium plating layer.

[0015] In some embodiments, the cyanide-free copper-zinc alloy coating is prepared by a polymerized thiocyanate copper-zinc alloy electroplating process: Polymeric cuprous thiocyanate 18-24 g / L, polymeric zinc thiocyanate 9-13 g / L, polymeric sodium thiocyanate 130-170 g / L, copper-zinc alloy electroplating 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 3 to 5 m / min, 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; The copper-zinc alloy electroplating 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.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The cyanide-free cadmium plating leveler and cadmium plating process of the present invention add the cyanide-free cadmium plating leveler to the original potassium chloride cyanide-free cadmium plating process, formulate a new potassium chloride cyanide-free cadmium plating process, effectively reduce the consumption of brightener, and improve the performance of the plating solution; 2. The cyanide-free cadmium plating leveler and cadmium plating process of the present invention overcome the defects of the original potassium chloride cyanide-free cadmium plating layer being prone to roughness and the military green passivation being prone to floweriness. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] 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 It is a metallographic photograph of a cadmium-plated layer magnified 1000 times by the potassium chloride cyanide-free cadmium plating process of the present invention with a leveling agent added; Figure 2 This is a metallographic photograph of the cadmium plating layer prepared by the potassium chloride cyanide-free cadmium plating process without adding a leveling agent, magnified 1000 times. DETAILED DESCRIPTION

[0018] 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.

[0019] A cyanide-free cadmium plating leveler, comprising the following ingredients and contents: Trimercapto-s-triazine 5-10 g / L, organic amine epoxy derivative 30-60 g / L, sodium hydroxide 5-10 g / L.

[0020] Preferably, the cyanide-free cadmium plating leveler is prepared as follows: Add 50 kg of deionized water and 0.5-1 kg of sodium hydroxide into the reaction tank, stir evenly, add 0.5-1 kg of trimercapto-s-triazine, stir until the solid is completely dissolved, then add 3-6 kg of organic amine epoxy derivatives, add water to 100 L, stir evenly to obtain the cyanide-free cadmium plating leveler.

[0021] Preferably, the organic amine epoxy derivative is an organic amine epoxy derivative with a product model of GDX.

[0022] A cyanide-free cadmium plating process includes the following components, contents, and process parameters: Cadmium chloride 25-35 g / L, potassium chloride 100-140 g / L, cyanide-free cadmium plating leveler 1.5-2.5 mL / L, PULIZIER NCC-617 AC complexing agent 100-140 g / L, PULIZIER NCC-617 Base auxiliary agent 25-30 mL / L, PULIZIER NCC-617 Bri brightener 1.5-2.5 mL / L, plating tank temperature 20-35 ° C, plating solution pH 7-9, cathode current density 0.5-1.5 A / dm 2 , cathode movement 2~4m / min, anode current density 1.0~2.5A / dm 2 The anode is made of a cadmium plate with a mass fraction of 99.97%.

[0023] Preferably, the cadmium plating process is used to prepare a cyanide-free cadmium plating layer on a steel substrate or an aluminum alloy substrate.

[0024] Preferably, a cyanide-free cadmium plating layer is prepared on the aluminum alloy substrate, and a chemical zinc deposition layer and a cyanide-free copper-zinc alloy plating layer are further included between the aluminum alloy substrate and the cadmium plating layer.

[0025] Preferably, the cyanide-free copper-zinc alloy coating is prepared by a polymerized thiocyanate copper-zinc alloy electroplating process: Polymeric cuprous thiocyanate 18-24 g / L, polymeric zinc thiocyanate 9-13 g / L, polymeric sodium thiocyanate 130-170 g / L, copper-zinc alloy electroplating 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 3 to 5 m / min, 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; The copper-zinc alloy electroplating 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.

[0026] Embodiment 1: A cyanide-free cadmium plating leveler and a cadmium plating process, comprising preparing a cyanide-free cadmium plating leveler, pre-treating a steel gold substrate, and sequentially preparing a cyanide-free cadmium plating layer and a hexavalent chromium color passivation layer from the inside to the outside on the pre-treated steel gold substrate.

[0027] 1. Pre-treatment: The existing pre-treatment process is adopted to carry out "chemical degreasing → water washing → acid washing → water washing → alkaline anodic electrolytic degreasing → water washing → activation → water washing" on the steel substrate.

[0028] 2. Cyanide-free cadmium plating: After pretreatment of the steel parts, the potassium chloride cyanide-free cadmium plating process of the present invention is adopted to prepare a cyanide-free cadmium plating layer, and the plating layer thickness is 12 μm.

[0029] 1) Preparation of cyanide-free cadmium plating leveling agent: Trimercapto-s-triazine, organic amine epoxy derivative sold by Wuhan Safek New Materials Co., Ltd. with product model GDX, and sodium hydroxide are dissolved in deionized water, and water is added to the required volume.

[0030] The prepared cyanide-free cadmium plating leveler contains 7.5 g / L of trimercapto-s-triazine, 45 g / L of organic amine epoxy derivative with product model GDX, and 7.5 g / L of sodium hydroxide.

[0031] 2) The cadmium plating layer is prepared by the following potassium chloride cyanide-free cadmium plating process: Cadmium chloride 35g / L, potassium chloride 140g / L, the cyanide-free cadmium plating leveler 2.0mL / L, PULIZIER NCC-617AC complexing agent 140g / L, PULIZIER NCC-617 Base auxiliary agent 30mL / L, PULIZIER NCC-617 Bri brightener 2.0mL / L, plating tank temperature 20°C, plating solution pH 9, cathode current density 1.0A / dm 2 , cathode movement 3m / min, anode current density 1.8A / dm 2 The anode is made of a cadmium plate with a mass fraction of 99.97%.

[0032] 3. Hydrogen removal: After cadmium plating, the steel parts are dehydrogenated at 200℃ for 24h.

[0033] 4. Hexavalent chromium color passivation: After cadmium plating, the hexavalent chromium color passivation layer is prepared using Chaobang Chemical's HC-5 high protection color passivator.

[0034] The volume concentration of HC-5 high protection color passivator is 4%, the passivation temperature is 20℃, the pH of the passivation liquid is 1.7, the passivation time is 6s, and weak air stirring is used.

[0035] The specific process is "light irradiation with 1.5% volume fraction nitric acid → water washing → passivation → water washing".

[0036] 5. Drying: After passivation, the steel parts are dried at 60℃ for 10 minutes.

[0037] Embodiment 2: A cyanide-free cadmium plating leveler and a cadmium plating process, comprising preparing a cyanide-free cadmium plating leveler, pre-treating a steel gold substrate, and sequentially preparing a cyanide-free cadmium plating layer, a hexavalent chromium color passivation layer, and a graphene modified sealing layer on the pre-treated steel gold substrate from the inside to the outside.

[0038] 1. Pre-treatment: The existing pre-treatment process is adopted to carry out "chemical degreasing → water washing → acid washing → water washing → alkaline anodic electrolytic degreasing → water washing → activation → water washing" on the steel substrate.

[0039] 2. Cyanide-free cadmium plating: After pretreatment of the steel parts, the potassium chloride cyanide-free cadmium plating process of the present invention is adopted to prepare a cyanide-free cadmium plating layer, and the plating layer thickness is 12 μm.

[0040] 1) Preparation of cyanide-free cadmium plating leveling agent: Trimercapto-s-triazine, organic amine epoxy derivative sold by Wuhan Safek New Materials Co., Ltd. with product model GDX, and sodium hydroxide are dissolved in deionized water, and water is added to the required volume.

[0041] The prepared cyanide-free cadmium plating leveler contains 7.5 g / L of trimercapto-s-triazine, 45 g / L of organic amine epoxy derivative with product model GDX, and 7.5 g / L of sodium hydroxide.

[0042] 2) The cadmium plating layer is prepared by the following potassium chloride cyanide-free cadmium plating process: Cadmium chloride 25g / L, potassium chloride 100g / L, the cyanide-free cadmium plating leveler 2.0mL / L, PULIZIER NCC-617AC complexing agent 100g / L, PULIZIER NCC-617 Base auxiliary agent 25mL / L, PULIZIER NCC-617 Bri brightener 2.0mL / L, plating tank temperature 35°C, plating solution pH 7, cathode current density 1.0A / dm 2 , cathode movement 3m / min, anode current density 1.2A / dm 2 The anode is made of a cadmium plate with a mass fraction of 99.97%.

[0043] 3. Hydrogen removal: After cadmium plating, the steel parts are dehydrogenated at 200℃ for 24h.

[0044] 4. Hexavalent chromium color passivation: After dehydrogenation of steel parts, the hexavalent chromium color passivation layer is prepared using Chaobang Chemical's HC-5 high protection color passivator.

[0045] The volume concentration of HC-5 high protection color passivator is 2%, the passivation temperature is 35℃, the pH of the passivation solution is 1.3, the passivation time is 13s, and the workpiece swings.

[0046] The specific process is "light irradiation with 1.5% volume fraction nitric acid → water washing → passivation → water washing".

[0047] 5. Closure: After the steel parts are passivated, PRODICO 480 graphene-modified sealant developed by Chaobang Chemical is used to prepare a graphene-modified sealing layer with a thickness of 1.2 μm.

[0048] Dilute PRODICO 480 graphene-modified sealer with water to 2.8 times to prepare a sealing solution. Immerse the passivated steel parts in the sealing solution for 8 seconds. Drain the parts after exiting the tank, and use high-pressure air to blow away the sealing solution remaining on the surface of the steel parts.

[0049] 6. Drying and curing: After the steel parts are sealed, they are dried and cured at 80°C for 30 minutes.

[0050] Embodiment 3: A cyanide-free cadmium plating leveler and cadmium plating process, comprising preparing a cyanide-free cadmium plating leveler, pre-treating an aluminum alloy substrate, and sequentially preparing a chemical zinc deposition layer, a cyanide-free copper-zinc alloy plating layer, a cyanide-free cadmium plating layer, and a hexavalent chromium color passivation layer on the pre-treated aluminum alloy substrate from the inside to the outside.

[0051] 1. Pre-treatment: The existing pre-treatment process is used to perform "chemical degreasing → water washing → ultrasonic degreasing → water washing → film removal → water washing → polishing → water washing → micro-corrosion → water washing" on the aluminum alloy substrate.

[0052] 2. Chemical zinc precipitation: After pre-treatment of aluminum alloy parts, the chemical zinc deposition layer is prepared using AZIN-113 acidic aluminum zinc deposition agent produced by Chaobang Chemical.

[0053] AZIN-113 acidic aluminum zinc precipitation agent 150mL / L, working temperature 30℃, bath pH 3.8, zinc precipitation time 70s.

[0054] The specific process is: "first zinc precipitation → water washing → zinc stripping → water washing → second zinc precipitation → water washing".

[0055] 3. Copper-zinc alloy plating: After chemical zinc deposition on aluminum alloy parts, the polythiocyanate copper-zinc alloy electroplating process developed by Chaobang Chemical was used to prepare a cyanide-free copper-zinc alloy coating with a coating thickness of 8μm.

[0056] Polymeric cuprous thiocyanate 17g / L, polymeric zinc thiocyanate 9g / L, polymeric sodium thiocyanate 130g / L, copper-zinc alloy electroplating brightener 8mL / L, plating solution pH 11.5, plating tank temperature 55℃, 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; The copper-zinc alloy electroplating brightener comprises the following components in weight fractions: 80 parts of N,N'-di-n-propylethylenediamine, 15 parts of waterborne polyurethane resin, 100 parts of polyacrylamide with a molecular weight less than 8000, and 820 parts of deionized water.

[0057] 4. Cyanide-free cadmium plating: After the aluminum alloy part is plated with copper-zinc alloy, the potassium chloride cyanide-free cadmium plating process of the present invention is used to prepare a cyanide-free cadmium plating layer, and the thickness of the plating layer is 12 μm.

[0058] 1) Preparation of cyanide-free cadmium plating leveling agent: Trimercapto-s-triazine, organic amine epoxy derivative sold by Wuhan Safek New Materials Co., Ltd. with product model GDX, and sodium hydroxide are dissolved in deionized water, and water is added to the required volume.

[0059] The prepared cyanide-free cadmium plating leveler contains 7.5 g / L of trimercapto-s-triazine, 45 g / L of organic amine epoxy derivative with product model GDX, and 7.5 g / L of sodium hydroxide.

[0060] 2) The cadmium plating layer is prepared by the following potassium chloride cyanide-free cadmium plating process: Cadmium chloride 30g / L, potassium chloride 120g / L, the cyanide-free cadmium plating leveler 2.0mL / L, PULIZIER NCC-617AC complexing agent 120g / L, PULIZIER NCC-617 Base auxiliary agent 28mL / L, PULIZIER NCC-617 Bri brightener 2.0mL / L, plating tank temperature 28°C, plating solution pH 8, cathode current density 1.0A / dm 2 , cathode movement 3m / min, anode current density 1.8A / dm 2 The anode is made of a cadmium plate with a mass fraction of 99.97%.

[0061] 5. Hexavalent chromium color passivation: After cadmium plating, the aluminum alloy parts are treated with HC-5 high protection color passivating agent produced by Chaobang Chemical to prepare the hexavalent chromium color passivation layer.

[0062] The volume concentration of HC-5 high protection color passivator is 3%, the passivation temperature is 28℃, the pH of the passivation solution is 1.7, the passivation time is 10s, and weak air stirring is used.

[0063] The specific process is "light irradiation with 1.5% volume fraction nitric acid → water washing → passivation → water washing".

[0064] 6. Drying: After passivation, the aluminum alloy parts were dried at 60°C for 10 minutes.

[0065] Embodiment 4: A cyanide-free cadmium plating leveler and a cadmium plating process, comprising preparing a cyanide-free cadmium plating leveler, pre-treating an aluminum alloy substrate, and sequentially preparing a chemical zinc deposition layer, a cyanide-free copper-zinc alloy plating layer, a cyanide-free cadmium plating layer, a hexavalent chromium color passivation layer, and a graphene modified sealing layer on the pre-treated aluminum alloy substrate from the inside to the outside.

[0066] 1. Pre-treatment: The existing pre-treatment process is used to perform "chemical degreasing → water washing → ultrasonic degreasing → water washing → film removal → water washing → polishing → water washing → micro-corrosion → water washing" on the aluminum alloy substrate.

[0067] 2. Chemical zinc precipitation: After pre-treatment of aluminum alloy parts, the chemical zinc deposition layer is prepared using AZIN-113 acidic aluminum zinc deposition agent produced by Chaobang Chemical.

[0068] AZIN-113 acidic aluminum zinc precipitation agent 240mL / L, working temperature 20℃, bath pH 3.8, zinc precipitation time 50s.

[0069] The specific process is: "first zinc precipitation → water washing → zinc stripping → water washing → second zinc precipitation → water washing".

[0070] 3. Copper-zinc alloy plating: After chemical zinc deposition on aluminum alloy parts, the polythiocyanate copper-zinc alloy electroplating process developed by Chaobang Chemical was used to prepare a cyanide-free copper-zinc alloy coating with a coating thickness of 8μm.

[0071] Polymeric cuprous thiocyanate 20g / L, polymeric zinc thiocyanate 10g / L, polymeric sodium thiocyanate 140g / L, copper-zinc alloy electroplating brightener 10g / L, plating solution pH 10.5, plating tank temperature 40℃, 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; The copper-zinc alloy electroplating brightener comprises the following components in weight fractions: 80 parts of N,N'-di-n-propylethylenediamine, 15 parts of waterborne polyurethane resin, 100 parts of polyacrylamide with a molecular weight less than 8000, and 820 parts of deionized water.

[0072] 4. Cyanide-free cadmium plating: After the aluminum alloy part is plated with copper-zinc alloy, the potassium chloride cyanide-free cadmium plating process of the present invention is used to prepare a cyanide-free cadmium plating layer, and the thickness of the plating layer is 12 μm.

[0073] 1) Preparation of cyanide-free cadmium plating leveling agent: Trimercapto-s-triazine, organic amine epoxy derivative sold by Wuhan Safek New Materials Co., Ltd. with product model GDX, and sodium hydroxide are dissolved in deionized water, and water is added to the required volume.

[0074] The prepared cyanide-free cadmium plating leveler contains 7.5 g / L of trimercapto-s-triazine, 45 g / L of organic amine epoxy derivative with product model GDX, and 7.5 g / L of sodium hydroxide.

[0075] 2) The cadmium plating layer is prepared by the following potassium chloride cyanide-free cadmium plating process: Cadmium chloride 33g / L, potassium chloride 130g / L, the cyanide-free cadmium plating leveler 2.0mL / L, PULIZIER NCC-617AC complexing agent 130g / L, PULIZIER NCC-617 Base auxiliary agent 30mL / L, PULIZIER NCC-617 Bri brightener 2.0mL / L, plating tank temperature 28°C, plating solution pH 8, cathode current density 1.0A / dm 2, cathode movement 3m / min, anode current density 1.8A / dm 2 The anode is made of a cadmium plate with a mass fraction of 99.97%.

[0076] 5. Hexavalent chromium color passivation: After cadmium plating, the aluminum alloy parts are treated with HC-5 high protection color passivating agent produced by Chaobang Chemical to prepare the hexavalent chromium color passivation layer.

[0077] The volume concentration of HC-5 high protection color passivator is 3.5%, the passivation temperature is 22°C, the pH of the passivation solution is 1.8, the passivation time is 8s, and the workpiece swings.

[0078] The specific process is "light irradiation with 1.5% volume fraction nitric acid → water washing → passivation → water washing".

[0079] 6. Closure: After the aluminum alloy parts are passivated, the graphene-modified sealing layer is prepared using PRODICO 480 graphene-modified sealing agent developed by Chaobang Chemical, and the thickness of the sealing layer is 1.2 μm.

[0080] The PRODICO 480 graphene-modified sealer was diluted with water to 2.8 times to prepare a sealing solution. The passivated aluminum alloy parts were immersed in the sealing solution for 12 seconds. After leaving the tank, the parts were drained and the sealing solution remaining on the surface of the aluminum alloy parts was blown away with high-pressure air.

[0081] 6. Drying and curing: After the aluminum alloy parts are sealed, they are dried and cured at 80°C for 30 minutes.

[0082] Test Example 1: The surface quality of the cadmium plating layer prepared by the potassium chloride cyanide-free cadmium plating process with the addition of a cyanide-free cadmium plating leveler of the present invention is detected.

[0083] The following new potassium chloride cyanide-free cadmium plating process is adopted: Cadmium chloride 30g / L, potassium chloride 120g / L, cyanide-free cadmium plating leveler 2.0mL / L, PULIZIER NCC-617 AC complexing agent 120g / L, PULIZIER NCC-617 Base auxiliary agent 28mL / L, PULIZIER NCC-617 Bri brightener 2.0mL / L, plating tank temperature 28℃, plating solution pH 8, cathode current density 1.0A / dm 2 , cathode movement 3m / min, anode current density 1.8A / dm 2 .

[0084] The brass test piece was degreased, wiped with a scouring pad and pickled, then plated with cadmium for 60 minutes, rinsed with water and dried with electric hot air. The surface quality of the cadmium-plated layer was observed under a microscope. Figure 1This is a metallographic photograph of the coating surface taken with a microscope and magnified 1000 times. The coating surface is flat and smooth.

[0085] Test Example 2: The surface quality of the cadmium plating layer prepared by the potassium chloride cyanide-free cadmium plating process without adding cyanide-free cadmium plating leveler was tested.

[0086] The following new potassium chloride cyanide-free cadmium plating process is adopted: Cadmium chloride 30g / L, potassium chloride 120g / L, PULIZIER NCC-617 AC complexing agent 120g / L, PULIZIERNCC-617 Base auxiliary agent 28mL / L, PULIZIER NCC-617 Bri brightener 2.0mL / L, plating tank temperature 28℃, plating solution pH 8, cathode current density 1.0A / dm 2 , cathode movement 3m / min, anode current density 1.8A / dm 2 .

[0087] The brass test piece was degreased, wiped with a scouring pad and pickled, then plated with cadmium for 60 minutes, rinsed with water and dried with electric hot air. The surface quality of the cadmium-plated layer was observed under a microscope. Figure 2 The metallographic photograph of the coating surface magnified 1000 times by a microscope shows that the coating surface is in the shape of fine branches. The comparison between Test Example 1 and Test Example 2 shows that the addition of 2.0 mL / L of the cyanide-free cadmium plating leveler of the present invention to the existing potassium chloride cyanide-free cadmium plating solution significantly improves the flatness and brightness of the cadmium plating layer.

[0088] Test Example 3: The consumption of the leveler, brightener and auxiliary agent in the new potassium chloride cyanide-free cadmium plating process of the present invention is detected.

[0089] The potassium chloride cyanide-free cadmium plating solution containing the leveler prepared in Test Example 1 was used to carry out a 267mL Hertz test. The plating was carried out at a current of 0.5A. Each test piece was plated for 1h. For each plated test piece, 0.05mL of cyanide-free cadmium plating leveler, 0.02mL of PULIZIER NCC-617Bri brightener, 0.05mL of PULIZIER NCC-617 Base auxiliary agent, and 0.5g of PULIZIER NCC-617 AC complexing agent were added. 50 test pieces were plated continuously, and the appearance of the cadmium plating layer remained basically the same. In this test example, the consumption of cyanide-free cadmium plating leveler was 100mL / kAh, the consumption of PULIZIER NCC-617 Bri brightener was 40mL / kAh, and the consumption of PULIZIER NCC-617Base auxiliary agent was 100mL / kAh.

[0090] Test example 4: To detect the consumption of brightener and auxiliary agent in the potassium chloride cyanide-free cadmium plating process without leveling agent.

[0091] The 267mL Hertz test was carried out using the potassium chloride cyanide-free cadmium plating solution without leveling agent prepared in Test Example 2. The plating was carried out at a current of 0.5A. Each test piece was plated for 1h. 0.1mL of PULIZIER NCC-617 Bri brightener, 0.05mL of PULIZIER NCC-617 Base auxiliary agent, and 0.5g of PULIZIER NCC-617 AC complexing agent were added to each plated test piece. After plating 50 test pieces continuously, it was observed that the appearance quality of the cadmium plating layer decreased with the extension of the electroplating time. In this test example, the consumption of PULIZIER NCC-617 Bri brightener was 200mL / kAh, and the consumption of PULIZIER NCC-617 Base auxiliary agent was 100mL / kAh. Comparison of Test Example 3 with Test Example 4 shows that after adding the cyanide-free cadmium plating leveler of the present invention to the current potassium chloride cyanide-free cadmium plating solution, the consumption of PULIZIER NCC-617 Bri brightener is reduced by 80%, which effectively overcomes the defect of large consumption of the current potassium chloride cyanide-free cadmium plating brightener.

[0092] Test Example 5: The 50th cadmium-plated test pieces of Test Examples 3 and 4 were respectively subjected to military green passivation using the OVG-31 military green passivation agent of Chaobang Chemical. The passivation process is as follows: OVG-31 military green passivator 100mL / L, passivation solution pH 1.3, passivation temperature 25℃, swing plated parts, passivation time 60s.

[0093] The cadmium-plated test piece in Test Example 3 had a normal military green appearance after military green passivation, and the cadmium-plated test piece in Test Example 4 had a military green appearance after military green passivation, but there were faint signs of blooming.

[0094] Test Example 6: The cadmium-plated + hexavalent chromium color passivation samples prepared in Example 1 and Example 3 were subjected to an acetate spray test for 450 hours in accordance with GB / T 10125-2021 "Artificial Atmosphere Corrosion Test Salt Spray Test", and no white corrosion products were generated on the surface of the plated parts. The cadmium-plated + hexavalent chromium color passivation + graphene-modified sealant sealed samples prepared in Example 2 and Example 4 were subjected to an acetate spray test for 520 hours, and no white corrosion products were generated on the surface. The cadmium plating layer prepared by the present invention has excellent corrosion resistance.

[0095] 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 above embodiments 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 are also considered to fall within the protection scope of the present invention.

Claims

1. A cyanide-free cadmium plating leveler, characterized in that: Contains the following ingredients and contents: Trimercapto-s-triazine 5-10 g / L, organic amine epoxy derivative 30-60 g / L, sodium hydroxide 5-10 g / L.

2. The cyanide-free cadmium plating leveler according to claim 1, characterized in that: The cyanide-free cadmium plating leveler is prepared as follows: Add 50 kg of deionized water and 0.5-1 kg of sodium hydroxide into the reaction tank, stir evenly, add 0.5-1 kg of trimercapto-s-triazine, stir until the solid is completely dissolved, then add 3-6 kg of organic amine epoxy derivatives, add water to 100 L, stir evenly to obtain the cyanide-free cadmium plating leveler.

3. The cyanide-free cadmium plating leveler according to claim 1 or 2, characterized in that: The organic amine epoxy derivative is an organic amine epoxy derivative with a product model of GDX.

4. The cyanide-free cadmium plating leveler according to claim 1 or 3, characterized in that: The amount of the non-cyanide cadmium plating leveler added to the non-cyanide cadmium plating solution is 1.5-2.5 mL / L.

5. The cyanide-free cadmium plating leveler according to claim 1 or 3, characterized in that: The cyanide-free cadmium plating leveler is applied to the existing cyanide-free cadmium plating solution.

6. The cyanide-free cadmium plating leveler according to any one of claims 1, 3 and 5, characterized in that: The cyanide-free cadmium plating leveler is applied to a potassium chloride cyanide-free cadmium plating solution.

7. A cyanide-free cadmium plating process, characterized in that: Contains the following ingredients, contents, and process parameters: Cadmium chloride 25-35 g / L, potassium chloride 100-140 g / L, the cyanide-free cadmium plating leveler 1.5-2.5 mL / L, PULIZIERNCC-617 AC complexing agent 100-140 g / L, PULIZIER NCC-617 Base auxiliary agent 25-30 mL / L, PULIZIERNCC-617 Bri brightener 1.5-2.5 mL / L, plating tank temperature 20-35 ° C, plating solution pH 7-9, cathode current density 0.5-1.5 A / dm 2 , cathode movement 2~4m / min, anode current density 1.0~2.5A / dm 2 The anode is made of cadmium plate with a mass fraction of 99.97%.

8. The cyanide-free cadmium plating process according to claim 7, characterized in that: The cadmium plating process is adopted to prepare a cyanide-free cadmium plating layer on a steel substrate or an aluminum alloy substrate.

9. The cyanide-free cadmium plating process according to claim 7 or 8, characterized in that: A cyanide-free cadmium plating layer is prepared on an aluminum alloy substrate, and a chemical zinc deposition layer and a cyanide-free copper-zinc alloy plating layer are also included between the aluminum alloy substrate and the cadmium plating layer.

10. The cyanide-free cadmium plating process according to claim 9, characterized in that: The cyanide-free copper-zinc alloy coating is prepared by using a polymerized thiocyanate copper-zinc alloy electroplating process: Polymeric cuprous thiocyanate 18-24 g / L, polymeric zinc thiocyanate 9-13 g / L, polymeric sodium thiocyanate 130-170 g / L, copper-zinc alloy electroplating 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 3 to 5 m / min, 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; The copper-zinc alloy electroplating 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.

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