Potassium chloride zinc-iron alloy plating solution and electroplating process

Abstract

The plating solution comprises the following components and process parameters: 50-70 g / L of zinc chloride, 2-12 g / L of ferrous chloride tetrahydrate, 180-220 g / L of potassium chloride, 25-35 g / L of boric acid, 8-40 g / L of a coordination agent, 0.1-0.2 mL / L of a brightening agent and 20-30 mL / L of an auxiliary agent, the pH value of the plating solution is 4.5-5.6, the temperature of a plating tank is 15-30 DEG C, the cathode current density is 1-3 A / dm < 2 >, and the cathode movement is 3-5 m / min. According to a neutral salt spray test for 480h according to GB / T 10125-2021 Artificial Atmosphere Corrosion Test Salt Spray Test, a galvanized iron alloy sample piece passivated by trivalent chromium blue and white and sealed by the graphene modified sealing agent has no white rust on the surface, and a coating has excellent corrosion resistance.

Description

Technical Field

[0001] The invention relates to the field of electroplating, in particular to a potassium chloride zinc iron alloy plating solution and an electroplating process. Background Art

[0002] With the industrial upgrading in my country, the electroplating process of zinc-nickel alloy has replaced the galvanizing process on a large scale. However, the zinc-nickel alloy plating solution contains highly antioxidant diethylenetriamine and other complexing agents, which brings great difficulties to the treatment of electroplating wastewater. [1] Based on this, the industry is trying to use a new process of electroplating zinc-iron alloy to replace zinc-nickel alloy, but no new breakthrough has been achieved so far.

[0003] Iron is a very cost-effective metal that can form alloys with common metals with excellent performance. In the field of electroplating, electroplating of alkaline zinc-iron alloys has been widely used. Due to the low iron content in the alkaline zinc-iron alloy plating solution, the mass fraction of iron in the coating is usually 0.3% to 0.7%. [2] The coating performance does not meet the requirements of zinc-nickel alloy coating. The ferrous ions in the acid zinc-iron alloy plating solution are easily oxidized by oxygen molecules to trivalent iron to form iron hydroxide precipitation, especially in the chloride acid zinc-iron alloy plating solution. Iron hydroxide precipitation will be generated after being left still for 5 days. [3] The application of acid zinc-iron alloy plating solution is limited due to the stability problem. So far, there is no report on the mass production of acid zinc-iron alloy electroplating.

[0004] The hydroxy graphene modified sealer developed in recent years can significantly improve the corrosion resistance and other properties of the coating. The prepared sealing layer has self-repairing properties. It is used to seal the zinc coating and zinc-nickel alloy coating after trivalent chromium passivation, overcoming the defect that the trivalent chromium passivation film does not have self-repairing properties. [4] .

[0005] References: [1]. Guo Chongwu, Lai Huanwen, Xia Liang, Combined treatment process of alkaline zinc-nickel alloy electroplating and passivation wastewater [J], Electroplating and Finishing, 2021, 40(7): 579-583. [2]. Zhang Zhao, Shu Yude, Li Xiaomei, Current status of electroplating of Zn-Fe alloy [J], Electroplating and Environmental Protection, 1998, 18(5): 7-11. [3]. Zhou Xiaorong, Liu Xiaobo, Hu Yu, et al., Study on electroplating of zinc-iron alloy in weakly acidic system of ammonium ferrous sulfate [J], Journal of Wuhan Polytechnic Institute, 2010, 29(1): 32-37. [4]. Guo Chongwu, Lai Huanwen, Xia Liang, Study on the performance of graphene oxide in plating sealant [J], Electroplating and Finishing, 2021, 40(9): 696-700. Summary of the invention

[0006] In order to solve the problem of poor stability of acidic zinc-iron alloy plating solution, the present invention provides a potassium chloride zinc-iron alloy plating solution and an electroplating process. In order to achieve the above purpose, the present invention adopts the following technical solutions: A potassium chloride zinc-iron alloy plating solution, comprising the following components and contents: Zinc chloride 50-70g / L, ferrous chloride tetrahydrate 2-12g / L, potassium chloride 180-220g / L, boric acid 25-35g / L, complexing agent 8-40g / L, brightener 0.1-0.2mL / L, auxiliary agent 20-30mL / L; The complexing agent includes sodium gluconate and sodium sulfosalicylate, and the mass ratio of sodium gluconate to sodium sulfosalicylate is 3:(1-3); The brightener comprises o-chlorobenzaldehyde and formic acid, and the mass ratio of o-chlorobenzaldehyde to formic acid is 1:(0.8-1.2); The auxiliary agent comprises a sulfonation product of fatty alcohol polyoxyethylene ether and aminosulfonic acid, sodium benzoate, and nicotinic acid. Calculated by weight, the sulfonation product of fatty alcohol polyoxyethylene ether and aminosulfonic acid comprises 17 to 23 parts, sodium benzoate comprises 5 to 7 parts, nicotinic acid comprises 0.4 to 0.6 parts, and water comprises 80 to 90 parts.

[0007] In some embodiments, the complexing agent, brightener, and auxiliary agent are prepared by the following method: a) mixing the two components together in a mass ratio of sodium glucoheptanoate to sodium sulfosalicylate of 3:(1-3), and stirring the two components to obtain the complexing agent; b) mixing the two components together in a mass ratio of o-chlorobenzaldehyde to formic acid of 1:(0.8-1.2), and stirring until the solid matter is dissolved to obtain the brightener; c) Add 17-23 kg of the sulfonation product of fatty alcohol polyoxyethylene ether and aminosulfonic acid, 5-7 kg of sodium benzoate, and 0.4-0.6 kg of nicotinic acid into 70 kg of water, stir to dissolve the solid matter, and add water to 100 L to obtain the auxiliary agent.

[0008] In some of the embodiments, the sulfonation product of fatty alcohol polyoxyethylene ether and aminosulfonic acid adopts the sulfonation product of fatty alcohol polyoxyethylene ether and aminosulfonic acid with model OX-105.

[0009] In some of the embodiments, the pH of the potassium chloride zinc-iron alloy plating solution is 4.5-5.6.

[0010] In some embodiments, the potassium chloride zinc iron alloy plating solution is prepared as follows: a) Add 70% water into the plating tank according to the volume of the plating solution, add zinc chloride, potassium chloride, boric acid, and complexing agent according to the process requirements, and stir to dissolve the above substances; b) Add ferrous chloride tetrahydrate according to the process requirements and stir until the solid matter is dissolved; c) Add brightener and auxiliary agent according to the process requirements, stir evenly, adjust the pH of the plating solution to 4.5-5.6 with 10% sodium hydroxide solution or 3% hydrochloric acid, and add water to the specified volume; d) 0.1~0.2A / dm 2 Electrolysis at current density for 30 to 90 minutes.

[0011] A potassium chloride zinc iron alloy electroplating process, comprising the following components and process parameters: Zinc chloride 50-70g / L, ferrous chloride tetrahydrate 2-12g / L, potassium chloride 180-220g / L, boric acid 25-35g / L, complexing agent 8-40g / L, brightener 0.1-0.2mL / L, auxiliary agent 20-30mL / L, plating solution pH 4.5-5.6, plating tank temperature 15-30℃, cathode current density 1-3A / dm 2 , the cathode moves 3 to 5 m / min.

[0012] In some of the embodiments, the anode is made of a zinc plate with a mass fraction of 99.9%.

[0013] In some embodiments, the area ratio of the cathode to the anode is 2:(0.7-1.3).

[0014] In some of the embodiments, a 30% by mass ferrous chloride tetrahydrate solution is added to the plating tank during production to maintain its mass concentration at 2-12 g / L.

[0015] In some of the embodiments, a filter is used to circulate and filter the plating solution during production.

[0016] In some embodiments, the potassium chloride zinc iron alloy electroplating process includes the following process: a) Prepare potassium chloride zinc-iron alloy plating solution; b) Pre-treat the workpiece using the current pre-treatment method; c) Galvanized iron alloy after pre-treatment of the workpiece; d) After the workpiece is plated with galvanized iron alloy, a trivalent chromium passivation film is prepared using the current trivalent chromium passivation process; e) After the workpiece is passivated with trivalent chromium, a graphene-modified sealing agent is used to prepare a graphene-modified sealing layer.

[0017] The beneficial effects of the present invention are: 1. The potassium chloride zinc-iron alloy plating solution and electroplating process disclosed in the present invention use sodium glucose heptanoate and sodium sulfosalicylate as complexing agents. Sodium glucose heptanoate forms stable complex ions with ferrous ions, which can effectively inhibit the oxidation of ferrous ions into trivalent ferrous ions. Sodium sulfosalicylate forms stable complex ions with a small amount of trivalent iron in the plating solution to eliminate its adverse effects. 2. The potassium chloride zinc-iron alloy plating solution and electroplating process disclosed in the present invention overcome the defect of poor stability of the traditional chloride acid zinc-iron alloy plating solution; 3. The potassium chloride zinc-iron alloy plating solution and electroplating process disclosed in the present invention have a zinc-iron alloy coating with a salt spray resistance significantly higher than that of the current acid zinc coating; 4. The potassium chloride zinc-iron alloy plating solution and electroplating process disclosed in the present invention use formic acid as a solvent to dissolve o-chlorobenzaldehyde, which significantly increases the content of o-chlorobenzaldehyde in the brightener and improves the cost performance of the brightener; 5. In the potassium chloride zinc-iron alloy plating solution and electroplating process disclosed by the present invention, the formic acid in the brightener has a strong reducing property and has an inhibitory effect on the formation of trivalent iron in the plating solution. 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 is a schematic diagram of the coating structure of Example 1 of the present invention, Figure 2 is a schematic diagram of the coating structure of Example 2 of the present invention, Figure 3 is a schematic diagram of the coating structure of Example 3 of the present invention, Figure 4 It is a schematic diagram of the coating structure of Example 4 of the present invention. DETAILED DESCRIPTION

[0019] For a better understanding of the present invention, the exemplary embodiments and descriptions described herein are used to explain the present invention but are not intended to limit the present invention.

[0020] A potassium chloride zinc iron alloy plating solution and electroplating process, comprising the preparation of a coordination agent, a brightener, an auxiliary agent, a potassium chloride zinc iron alloy plating solution, workpiece pretreatment, zinc iron alloy plating, passivation, and sealing.

[0021] Preferably, the complexing agent includes sodium gluconate and sodium sulfosalicylate, the mass ratio of sodium gluconate to sodium sulfosalicylate is 3:(1-3), and the two are mixed and stirred evenly to obtain the complexing agent.

[0022] Preferably, the brightener comprises o-chlorobenzaldehyde and formic acid, the mass ratio of o-chlorobenzaldehyde to formic acid is 1:(0.8-1.2), and the two components are mixed and stirred until the solid matter is dissolved to obtain the above-mentioned brightener; The auxiliary agent includes a sulfonation product of fatty alcohol polyoxyethylene ether and aminosulfonic acid, sodium benzoate, and nicotinic acid. 17-23 kg of the sulfonation product of fatty alcohol polyoxyethylene ether and aminosulfonic acid, 5-7 kg of sodium benzoate, and 0.4-0.6 kg of nicotinic acid are added to 70 kg of water, stirred to dissolve the solid matter, and then water is added to 100 L to obtain the auxiliary agent.

[0023] Preferably, the sulfonation product of fatty alcohol polyoxyethylene ether and aminosulfonic acid is a sulfonation product of fatty alcohol polyoxyethylene ether and aminosulfonic acid of model OX-105.

[0024] Preferably, the potassium chloride zinc-iron alloy plating solution is prepared as follows: a) Add 70% water into the plating tank according to the volume of the plating solution, add zinc chloride, potassium chloride, boric acid, and complexing agent according to the process requirements, and stir to dissolve the above substances; b) Add ferrous chloride tetrahydrate according to the process requirements and stir until the solid matter is dissolved; c) Add brightener and auxiliary agent according to the process requirements, stir evenly, adjust the pH of the plating solution to 4.5-5.6 with 10% sodium hydroxide solution or 3% hydrochloric acid, and add water to the specified volume; d) 0.1~0.2A / dm 2 The current density is used for electrolysis for 30 to 90 minutes.

[0025] Preferably, the potassium chloride zinc iron alloy electroplating process includes the following components and process parameters: Zinc chloride 50-70g / L, ferrous chloride tetrahydrate 2-12g / L, potassium chloride 180-220g / L, boric acid 25-35g / L, complexing agent 8-40g / L, brightener 0.1-0.2mL / L, auxiliary agent 20-30mL / L, plating solution pH 4.5-5.6, plating tank temperature 15-30℃, cathode current density 1-3A / dm 2 The cathode moves 3 to 5 m / min, the anode is made of zinc plate with a mass fraction of 99.9%, and the area ratio of cathode to anode is 2:(0.7 to 1.3).

[0026] Preferably, during production, 30% by mass of ferrous chloride tetrahydrate solution is added to the plating tank to maintain its mass concentration at 2-12 g / L.

[0027] Preferably, a filter is used to circulate and filter the plating solution during production.

[0028] Preferably, the potassium chloride zinc-iron alloy electroplating process comprises the following steps: a) Prepare potassium chloride zinc-iron alloy plating solution; b) Pre-treat the workpiece using the current pre-treatment method; c) Galvanized iron alloy after pre-treatment of the workpiece; d) After the workpiece is plated with galvanized iron alloy, a trivalent chromium passivation film is prepared using the current trivalent chromium passivation process; e) After the workpiece is passivated with trivalent chromium, a graphene-modified sealing agent is used to prepare a graphene-modified sealing layer.

[0029] The method of plating galvanized iron alloy on the aluminum alloy part also includes a chemical zinc deposition process to prepare a chemical zinc deposition layer on the surface of the aluminum alloy.

[0030] Preferably, the trivalent chromium passivation film is prepared by using the TRIROS 348 zinc-iron blue-white passivation process of Chaobang Chemical: TRIROS 348 zinc iron blue-white passivator 135-175 mL / L, passivation solution pH 1.8-2.6, operating temperature 30-60°C, immersion time 30-60s, air stirring.

[0031] Preferably, the graphene-modified sealing layer is prepared using PRODICO 480 graphene-modified sealing agent developed by Chaobang Chemical: Dilute PRODICO 480 graphene modified sealer with water to 2.5-3.2 times to prepare the sealing solution. Immerse the plated parts in the sealing solution for 8-15 seconds. Drain after leaving the tank and use high-pressure air to blow away the sealing solution remaining on the surface of the plated parts. After sealing, dry and cure at 70-85°C for 20-35 minutes.

[0032] Preferably, the chemical zinc deposition layer is prepared by using the ALBUME AS-699 cyanide-free aluminum zinc deposition process of Chaobang Chemical: ALBUME AS-699 cyanide-free aluminum zinc precipitation agent 150 ~ 170mL / L, the working solution contains zinc ions 6 ~ 9g / L, copper ions 0.16 ~ 0.20g / L, the operating temperature is 20 ℃ ~ 30 ℃, the zinc precipitation time is 60 ~ 120s.

[0033] Embodiment 1: A potassium chloride zinc iron alloy plating solution and electroplating process, comprising the preparation of a complexing agent, a brightener, an auxiliary agent, a potassium chloride zinc iron alloy plating solution, workpiece pretreatment, zinc iron alloy plating, passivation, and sealing.

[0034] like Figure 1 As shown, the coating structure prepared by the potassium chloride zinc-iron alloy electroplating process includes a steel substrate 01, and a zinc-iron alloy coating 02, a trivalent chromium blue-white passivation film 03, and a graphene-modified sealing layer 04 prepared on the steel substrate 01 from the inside to the outside.

[0035] 1. Preparation of zinc-iron alloy electroplating additives: The zinc-iron alloy electroplating additives include a complexing agent, a brightener, and an auxiliary agent.

[0036] 1) Preparation of complexing agent: Sodium glucose heptanate and sodium sulfosalicylate are mixed together in a mass ratio of 3:2, and stirred evenly to obtain the complexing agent.

[0037] 2) Prepare brightener: Mix o-chlorobenzaldehyde and formic acid in a mass ratio of 1:1 and stir until the solid matter is dissolved to obtain the above-mentioned brightener; 3) Preparation of auxiliary agents: In 70 kg of water, 20 kg of the sulfonation product of fatty alcohol polyoxyethylene ether model OX-105 produced by Jihechang and aminosulfonic acid, 6 kg of sodium benzoate, and 0.5 kg of nicotinic acid were added, stirred to dissolve the solid matter, and water was added to 100 L to obtain the auxiliary agent.

[0038] 4) Preparation of potassium chloride zinc-iron alloy plating solution: The potassium chloride zinc-iron alloy plating solution is prepared as follows: a) Add 70% water into the plating tank according to the volume of the plating solution, add zinc chloride, potassium chloride, boric acid, and complexing agent according to the process requirements, and stir to dissolve the above substances; b) Add ferrous chloride tetrahydrate according to the process requirements and stir until the solid matter is dissolved; c) Add brightener and auxiliary agent according to the process requirements, stir evenly, adjust the pH of the plating solution to 5 with 10% by mass sodium hydroxide solution or 3% by mass hydrochloric acid, and add water to the specified volume; d) 0.15A / dm 2 The current density was used for electrolysis for 60 min.

[0039] 2. Pre-treatment: The existing pre-treatment process is adopted to carry out "chemical degreasing → water washing → acid washing → water washing → alkaline cathode electrolytic degreasing → water washing → alkaline anode electrolytic degreasing → water washing → activation → water washing" on the steel substrate 01.

[0040] 3. Galvanized iron alloy: After pretreatment of the steel parts, the potassium chloride zinc-iron alloy electroplating process of the present invention is used to prepare the zinc-iron alloy coating 02, and the coating thickness is 12 μm.

[0041] Zinc chloride 60g / L, ferrous chloride tetrahydrate 10g / L, potassium chloride 200g / L, boric acid 30g / L, complexing agent 35g / L, brightener 0.15mL / L, auxiliary agent 25mL / L, plating solution pH 5, plating tank temperature 20℃, cathode current density 2A / dm 2The cathode moves at 4 m / min, the anode is made of a zinc plate with a mass fraction of 99.9%, and the area ratio of the cathode to the anode is 2:1; the plating solution is circulated and filtered by a filter during production; and a 30% mass fraction ferrous chloride tetrahydrate solution is added to the plating tank to maintain its mass concentration at the required concentration.

[0042] 4. Passivation: After the steel parts are plated with galvanized iron alloy, the TRIROS 348 zinc-iron blue-white passivation process of Chaobang Chemical is used to prepare the trivalent chromium blue-white passivation film 03.

[0043] TRIROS 348 zinc iron blue-white passivator 150mL / L, passivation solution pH 2.4, operating temperature 45℃, immersion time 45s, air stirring.

[0044] The specific process is: 0.2% sulfuric acid film removal → water washing → passivation → water washing.

[0045] 5. Closure: After the steel parts are passivated, the graphene-modified sealing layer 04 is prepared using PRODICO 480 graphene-modified sealing agent developed by Chaobang Chemical.

[0046] Dilute PRODICO 480 graphene-modified sealer with water to 2.8 times to prepare the sealing solution. Immerse the plated parts in the sealing solution for 10 seconds, drain them after leaving the tank, and use high-pressure air to blow away the sealing solution remaining on the surface of the plated parts. After sealing, dry and cure them at 80°C for 25 minutes.

[0047] Embodiment 2: A potassium chloride zinc iron alloy plating solution and electroplating process, comprising the preparation of a coordination agent, a brightener, an auxiliary agent, a potassium chloride zinc iron alloy plating solution, workpiece pretreatment, zinc iron alloy plating, passivation, and sealing.

[0048] like Figure 2 As shown, the coating structure prepared by the potassium chloride zinc-iron alloy electroplating process includes a zinc alloy substrate 11, and a zinc-iron alloy coating 12, a trivalent chromium blue-white passivation film 13, and a graphene modified sealing layer 14 prepared sequentially from the inside to the outside on the zinc alloy substrate 11.

[0049] 1. Preparation of zinc-iron alloy electroplating additives: The zinc-iron alloy electroplating additives include a complexing agent, a brightener, and an auxiliary agent.

[0050] 1) Preparation of complexing agent: Sodium glucose heptanate and sodium sulfosalicylate are mixed together in a mass ratio of 3:2, and stirred evenly to obtain the complexing agent.

[0051] 2) Prepare brightener: Mix o-chlorobenzaldehyde and formic acid in a mass ratio of 1:1 and stir until the solid matter is dissolved to obtain the above-mentioned brightener; 3) Preparation of auxiliary agents: In 70 kg of water, 20 kg of the sulfonation product of fatty alcohol polyoxyethylene ether model OX-105 produced by Jihechang and aminosulfonic acid, 6 kg of sodium benzoate, and 0.5 kg of nicotinic acid were added, stirred to dissolve the solid matter, and water was added to 100 L to obtain the auxiliary agent.

[0052] 4) Preparation of potassium chloride zinc-iron alloy plating solution: The potassium chloride zinc-iron alloy plating solution is prepared as follows: a) Add 70% water into the plating tank according to the volume of the plating solution, add zinc chloride, potassium chloride, boric acid, and complexing agent according to the process requirements, and stir to dissolve the above substances; b) Add ferrous chloride tetrahydrate according to the process requirements and stir until the solid matter is dissolved; c) Add brightener and auxiliary agent according to the process requirements, stir evenly, adjust the pH of the plating solution to 4.6 with 10% sodium hydroxide solution or 3% hydrochloric acid, and add water to the specified volume; d) at 0.15A / dm 2 The electrolysis was carried out for 60 min at the current density.

[0053] 2. Pre-treatment: The zinc alloy die casting substrate 11 is subjected to "chemical dewaxing → water washing → ultrasonic dewaxing → water washing → ultrasonic degreasing → water washing → activation → water washing" by using the existing pre-treatment process.

[0054] 3. Galvanized iron alloy: After the zinc alloy die casting is pre-treated, the potassium chloride zinc-iron alloy electroplating process of the present invention is used to prepare the zinc-iron alloy coating 12, and the coating thickness is 16 μm.

[0055] Zinc chloride 70g / L, ferrous chloride tetrahydrate 10g / L, potassium chloride 220g / L, boric acid 35g / L, complexing agent 40g / L, brightener 0.15mL / L, auxiliary agent 25mL / L, plating solution pH 4.6, plating tank temperature 25℃, cathode current density 2A / dm 2 The cathode moves at 4 m / min, the anode is made of a zinc plate with a mass fraction of 99.9%, and the area ratio of the cathode to the anode is 2:1; the plating solution is circulated and filtered by a filter during production; and a 30% mass fraction ferrous chloride tetrahydrate solution is added to the plating tank to maintain its mass concentration at the required concentration.

[0056] 4. Passivation: After zinc alloy die castings are plated with galvanized iron alloy, the trivalent chromium blue-white passivation film is prepared using the TRIROS 348 zinc-iron blue-white passivation process of Chaobang Chemical13.

[0057] TRIROS 348 zinc iron blue-white passivator 175mL / L, passivation solution pH 2.4, operating temperature 40℃, immersion time 40s, air stirring.

[0058] The specific process is: 0.2% sulfuric acid film removal → water washing → passivation → water washing.

[0059] 5. Closure: After the zinc alloy die casting is passivated, the graphene-modified sealing layer 14 is prepared using PRODICO 480 graphene-modified sealing agent developed by Chaobang Chemical.

[0060] Dilute PRODICO 480 graphene-modified sealer with water to 2.8 times to prepare the sealing solution. Immerse the plated parts in the sealing solution for 10 seconds, drain them after leaving the tank, and use high-pressure air to blow away the sealing solution remaining on the surface of the plated parts. After sealing, dry and cure them at 85°C for 20 minutes.

[0061] Embodiment 3: A potassium chloride zinc iron alloy plating solution and electroplating process, comprising the preparation of a complexing agent, a brightener, an auxiliary agent, a potassium chloride zinc iron alloy plating solution, workpiece pretreatment, zinc iron alloy plating, passivation, and sealing.

[0062] like Figure 3 As shown, the coating structure prepared by the potassium chloride zinc-iron alloy electroplating process includes a cast iron substrate 21, and a zinc-iron alloy coating 22, a trivalent chromium blue-white passivation film 23, and a graphene modified sealing layer 24 prepared sequentially from the inside to the outside on the cast iron substrate 21.

[0063] 1. Preparation of zinc-iron alloy electroplating additives: The zinc-iron alloy electroplating additives include a complexing agent, a brightener, and an auxiliary agent.

[0064] 1) Preparation of complexing agent: Sodium glucose heptanoate and sodium sulfosalicylate are mixed together in a mass ratio of 3:2, and stirred evenly to obtain the complexing agent.

[0065] 2) Prepare brightener: Mix o-chlorobenzaldehyde and formic acid in a mass ratio of 1:1 and stir until the solid matter is dissolved to obtain the above-mentioned brightener; 3) Preparation of auxiliary agents: In 70 kg of water, 20 kg of the sulfonation product of fatty alcohol polyoxyethylene ether model OX-105 produced by Jihechang and aminosulfonic acid, 6 kg of sodium benzoate, and 0.5 kg of nicotinic acid were added, stirred to dissolve the solid matter, and water was added to 100 L to obtain the auxiliary agent.

[0066] 4) Preparation of potassium chloride zinc-iron alloy plating solution: The potassium chloride zinc-iron alloy plating solution is prepared as follows: a) Add 70% water into the plating tank according to the volume of the plating solution, add zinc chloride, potassium chloride, boric acid, and complexing agent according to the process requirements, and stir to dissolve the above substances; b) Add ferrous chloride tetrahydrate according to the process requirements and stir until the solid matter is dissolved; c) Add brightener and auxiliary agent according to the process requirements, stir evenly, adjust the pH of the plating solution to 5.3 with 10% sodium hydroxide solution or 3% hydrochloric acid, and add water to the specified volume; d) At 0.1A / dm 2 The electrolysis was carried out for 90 min at the current density.

[0067] 2. Pre-treatment: The cast iron substrate 21 is subjected to the current pre-treatment process of "chemical degreasing → water washing → acid washing → water washing → alkaline cathode electrolytic degreasing → water washing → alkaline anode electrolytic degreasing → water washing → activation → water washing".

[0068] 3. Galvanized iron alloy: After the pretreatment of the cast iron part, the potassium chloride zinc-iron alloy electroplating process of the present invention is used to prepare the zinc-iron alloy coating 22, and the coating thickness is 16 μm.

[0069] Zinc chloride 50g / L, ferrous chloride tetrahydrate 8g / L, potassium chloride 180g / L, boric acid 25g / L, complexing agent 25g / L, brightener 0.15mL / L, auxiliary agent 25mL / L, plating solution pH 5.3, plating tank temperature 23℃, cathode current density 2A / dm 2 The cathode moves at 4 m / min, the anode is made of a zinc plate with a mass fraction of 99.9%, and the area ratio of the cathode to the anode is 2:1; the plating solution is circulated and filtered by a filter during production; and a 30% mass fraction ferrous chloride tetrahydrate solution is added to the plating tank to maintain its mass concentration at the required concentration.

[0070] 4. Passivation: After the cast iron parts are plated with galvanized iron alloy, the trivalent chromium blue-white passivation film is prepared using the TRIROS 348 zinc-iron blue-white passivation process of Chaobang Chemical23.

[0071] TRIROS 348 zinc iron blue-white passivator 135mL / L, passivation solution pH 2.0, operating temperature 50℃, immersion time 45s, air stirring.

[0072] The specific process is: 0.2% sulfuric acid film removal → water washing → passivation → water washing.

[0073] 5. Closure: After the cast iron parts are passivated, the graphene-modified sealing layer 24 is prepared using PRODICO 480 graphene-modified sealing agent developed by Chaobang Chemical.

[0074] Dilute PRODICO 480 graphene-modified sealer with water to 2.8 times to prepare the sealing solution. Immerse the plated parts in the sealing solution for 10 seconds, drain them after leaving the tank, and use high-pressure air to blow away the sealing solution remaining on the surface of the plated parts. After sealing, dry and cure them at 70°C for 35 minutes.

[0075] Embodiment 4: A potassium chloride zinc iron alloy plating solution and electroplating process, comprising the preparation of a coordination agent, a brightener, an auxiliary agent, a potassium chloride zinc iron alloy plating solution, workpiece pretreatment, zinc iron alloy plating, passivation, and sealing.

[0076] like Figure 4 As shown, the coating structure prepared by the potassium chloride zinc-iron alloy electroplating process includes an aluminum alloy substrate 1, and a chemical zinc deposition layer 2, a zinc-iron alloy coating 3, a trivalent chromium blue-white passivation film 4, and a graphene modified sealing layer 5 prepared sequentially from the inside to the outside on the aluminum alloy substrate 1.

[0077] 1. Preparation of zinc-iron alloy electroplating additives: The zinc-iron alloy electroplating additives include a complexing agent, a brightener, and an auxiliary agent.

[0078] 1) Preparation of complexing agent: Sodium glucose heptanate and sodium sulfosalicylate are mixed together in a mass ratio of 3:2, and stirred evenly to obtain the complexing agent.

[0079] 2) Prepare brightener: Mix o-chlorobenzaldehyde and formic acid in a mass ratio of 1:1 and stir until the solid matter is dissolved to obtain the above-mentioned brightener; 3) Preparation of auxiliary agents: In 70 kg of water, 20 kg of the sulfonation product of fatty alcohol polyoxyethylene ether model OX-105 produced by Jihechang and aminosulfonic acid, 6 kg of sodium benzoate, and 0.5 kg of nicotinic acid were added, stirred to dissolve the solid matter, and water was added to 100 L to obtain the auxiliary agent.

[0080] 4) Preparation of potassium chloride zinc-iron alloy plating solution: The potassium chloride zinc-iron alloy plating solution is prepared as follows: a) Add 70% water into the plating tank according to the volume of the plating solution, add zinc chloride, potassium chloride, boric acid, and complexing agent according to the process requirements, and stir to dissolve the above substances; b) Add ferrous chloride tetrahydrate according to the process requirements and stir until the solid matter is dissolved; c) Add brightener and auxiliary agent according to the process requirements, stir evenly, adjust the pH of the plating solution to 4.5-5.6 with 10% sodium hydroxide solution or 3% hydrochloric acid, and add water to the specified volume; d) At 0.2A / dm 2 Electrolysis was carried out for 30 min at the current density.

[0081] 2. Pre-treatment: The aluminum alloy substrate 1 is subjected to "chemical degreasing → water washing → ultrasonic degreasing → water washing → alkaline corrosion → water washing → polishing → water washing → micro-corrosion → water washing" by using the current pre-treatment process.

[0082] 3. Chemical zinc precipitation: After pre-treatment of the aluminum alloy parts, the chemical zinc deposition layer 2 is prepared by using the ALBUME AS-699 cyanide-free aluminum zinc deposition process of Chaobang Chemical.

[0083] ALBUME AS-699 cyanide-free aluminum zinc precipitation agent 160mL / L, the working solution contains 7.5g / L zinc ions and 0.18g / L copper ions, the operating temperature is 25℃, and the zinc precipitation time is 90s.

[0084] The specific process flow is: first chemical zinc precipitation → water washing → zinc stripping → water washing → second chemical zinc precipitation → water washing.

[0085] 4. Galvanized iron alloy: After chemical zinc deposition on the aluminum alloy part, the potassium chloride zinc-iron alloy electroplating process of the present invention is used to prepare a zinc-iron alloy coating 3, and the coating thickness is 12 μm.

[0086] Zinc chloride 65g / L, ferrous chloride tetrahydrate 11g / L, potassium chloride 210g / L, boric acid 30g / L, complexing agent 37g / L, brightener 0.15mL / L, auxiliary agent 25mL / L, plating solution pH 5.4, plating tank temperature 25℃, cathode current density 2A / dm 2 The cathode moves at 4 m / min, the anode is made of a zinc plate with a mass fraction of 99.9%, and the area ratio of the cathode to the anode is 2:1; the plating solution is circulated and filtered by a filter during production; and a 30% mass fraction ferrous chloride tetrahydrate solution is added to the plating tank to maintain its mass concentration at the required concentration.

[0087] 5. Passivation: After the aluminum alloy parts are plated with galvanized iron alloy, the trivalent chromium blue-white passivation film is prepared using the TRIROS 348 zinc-iron blue-white passivation process of Chaobang Chemical 4.

[0088] TRIROS 348 zinc iron blue-white passivator 160mL / L, passivation solution pH 2.2, operating temperature 50℃, immersion time 35s, air stirring.

[0089] The specific process is: 0.2% sulfuric acid film removal → water washing → passivation → water washing.

[0090] 6. Closure: After the aluminum alloy parts are passivated, the graphene-modified sealing layer 5 is prepared using PRODICO 480 graphene-modified sealing agent developed by Chaobang Chemical.

[0091] Dilute PRODICO 480 graphene-modified sealer with water to 2.8 times to prepare the sealing solution. Immerse the plated parts in the sealing solution for 10 seconds, drain them after leaving the tank, and use high-pressure air to blow away the sealing solution remaining on the surface of the plated parts. After sealing, dry and cure them at 75°C for 30 minutes.

[0092] Test Example 1: The galvanized iron alloy samples prepared in Examples 1 to 4 were subjected to a neutral salt spray test for 480 hours according to GB / T 10125-2021 "Artificial atmosphere corrosion test salt spray test" and had no white rust on the surface. The salt spray resistance of the coating prepared by the present invention is much higher than the requirement of no white rust for 216 hours in GB-T 41950-2022 "Zinc and zinc alloy electroplating layers on metal covering steel without hexavalent chromium treatment".

[0093] Test Example 2: The galvanized iron alloy samples prepared in Examples 1 to 4 were tested for coating adhesion according to GB / T 5270-2005 "Review of Test Methods for Adhesion Strength of Electrodeposited and Chemically Deposited Metal Coatings on Metal Substrates". The steel and cast iron plated parts were placed in a heating furnace and heated to 250°C for 30 minutes, the zinc alloy plated parts were placed in a heating furnace and heated to 150°C for 30 minutes, and the aluminum alloy plated parts were placed in a heating furnace and heated to 220°C for 30 minutes. After heating, they were taken out and immediately placed in water at room temperature for cooling. The coating did not blister or fall off. The test shows that the coating structure prepared by the present invention has good adhesion.

[0094] Test Example 3: The galvanized iron alloy samples prepared in Examples 1 to 4 were subjected to a mold test for 28 days according to GJB 150.9A-2009 "Military Equipment Laboratory Environmental Test Methods Part 10: Mold Test". No mold was generated on the surface of the samples, which met the environmental test requirements.

[0095] Test example 4: Prepare 1000mL potassium chloride zinc iron alloy plating solution, including 70g / L zinc chloride, 12g / L ferrous chloride tetrahydrate, 220g / L potassium chloride, 35g / L boric acid, 35g / L complexing agent, 0.2mL / L brightener, 30mL / L auxiliary agent, and the pH of the plating solution is 5.6. After the plating solution is placed in the laboratory for 1 month, no precipitate is generated in the plating solution.

[0096] Test Example 5: The potassium chloride zinc-iron alloy plating solution configured in Test Example 4 was used to continuously perform a 250mL Hull cell test, with 1A current for 10 minutes to plate one test piece, and brightener, auxiliary agent, complexing agent, ferrous chloride, and potassium chloride were added according to the changes in the test pieces. A total of 120 test pieces were plated, and no ferric hydroxide precipitate appeared in the plating solution. The plating solution had good covering ability, the coating was bright, and the appearance of the coating did not change significantly during the continuous electroplating.

[0097] Comparative Example 1: According to the process flow of Example 1, the ZINLITE 401 potassium chloride zinc plating process of Chaobang Chemical was used to replace the galvanized iron alloy process in this embodiment, and the steel parts were successively zinc plated, trivalent chromium blue-white passivated, and graphene modified sealant sealed. According to GB / T 10125-2021 "Artificial atmosphere corrosion test salt spray test", a neutral salt spray test was carried out, and the prepared galvanized sample had no white rust on the surface after 320 hours.

[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, and these should fall within the scope of protection of the present invention.

Claims

1. A potassium chloride zinc-iron alloy plating solution, characterized in that It includes the following components and contents: Zinc chloride 50-70g / L, ferrous chloride tetrahydrate 2-12g / L, potassium chloride 180-220g / L, boric acid 25-35g / L, complexing agent 8-40g / L, brightener 0.1-0.2mL / L, auxiliary agent 20-30mL / L; The complexing agent includes sodium gluconate and sodium sulfosalicylate, and the mass ratio of sodium gluconate to sodium sulfosalicylate is 3:(1-3); The brightener comprises o-chlorobenzaldehyde and formic acid, and the mass ratio of o-chlorobenzaldehyde to formic acid is 1:(0.8-1.2); The auxiliary agent comprises a sulfonation product of fatty alcohol polyoxyethylene ether and aminosulfonic acid, sodium benzoate, and nicotinic acid. Calculated by weight, the sulfonation product of fatty alcohol polyoxyethylene ether and aminosulfonic acid comprises 17 to 23 parts, sodium benzoate comprises 5 to 7 parts, nicotinic acid comprises 0.4 to 0.6 parts, and water comprises 80 to 90 parts.

2. The potassium chloride, zinc-iron alloy plating solution according to claim 1, characterized in that The complexing agent, brightener, and auxiliary agent are prepared by the following method: a) mixing the two components together in a mass ratio of sodium glucoheptanoate to sodium sulfosalicylate of 3:(1-3), and stirring the two components to obtain the complexing agent; b) mixing the two components together in a mass ratio of o-chlorobenzaldehyde to formic acid of 1:(0.8-1.2), and stirring until the solid matter is dissolved to obtain the brightener; c) Add 17-23 kg of the sulfonation product of fatty alcohol polyoxyethylene ether and aminosulfonic acid, 5-7 kg of sodium benzoate, and 0.4-0.6 kg of nicotinic acid into 70 kg of water, stir to dissolve the solid matter, and add water to 100 L to obtain the auxiliary agent.

3. The potassium chloride, zinc-iron alloy plating solution according to claim 1 or 2, characterized in that: The sulfonation product of fatty alcohol polyoxyethylene ether and aminosulfonic acid adopts the sulfonation product of fatty alcohol polyoxyethylene ether and aminosulfonic acid with model OX-105.

4. The potassium chloride, zinc-iron alloy plating solution according to claim 1, characterized in that: The pH value of the potassium chloride zinc-iron alloy plating solution is 4.5-5.

6.

5. The potassium chloride, zinc-iron alloy plating solution according to claim 1, characterized in that The plating solution is prepared as follows: a) Add 70% water into the plating tank according to the volume of the plating solution, add zinc chloride, potassium chloride, boric acid, and complexing agent according to the process requirements, and stir to dissolve the above substances; b) Add ferrous chloride tetrahydrate according to the process requirements and stir until the solid matter is dissolved; c) Add brightener and auxiliary agent according to the process requirements, stir evenly, adjust the pH of the plating solution to 4.5-5.6 with 10% sodium hydroxide solution or 3% hydrochloric acid, and add water to the specified volume; d) 0.1~0.2A / dm 2 The current density is used for electrolysis for 30 to 90 minutes.

6. A potassium chloride zinc iron alloy electroplating process, characterized in that: Includes the following components and process parameters: Zinc chloride 50-70g / L, ferrous chloride tetrahydrate 2-12g / L, potassium chloride 180-220g / L, boric acid 25-35g / L, complexing agent 8-40g / L, brightener 0.1-0.2mL / L, auxiliary agent 20-30mL / L, plating solution pH 4.5-5.6, plating tank temperature 15-30℃, cathode current density 1-3A / dm 2 , the cathode moves 3 to 5 m / min.

7. The potassium chloride, zinc-iron alloy electroplating process according to claim 6, characterized in that: The anode is made of zinc plate with a mass fraction of 99.9%.

8. The potassium chloride, zinc and iron alloy electroplating process according to claim 6, characterized in that: The area ratio of cathode to anode is 2:(0.7~1.3).

9. The potassium chloride, zinc and iron alloy electroplating process according to claim 6, characterized in that: During production, 30% by mass of ferrous chloride tetrahydrate solution is added to the plating tank to maintain its mass concentration at 2-12 g / L.

10. The potassium chloride, zinc and iron alloy electroplating process according to claim 6, characterized in that: The process includes the following steps: a) Prepare potassium chloride zinc-iron alloy plating solution; b) Pre-treat the workpiece using the current pre-treatment method; c) Galvanized iron alloy after pre-treatment of the workpiece; d) After the workpiece is plated with galvanized iron alloy, a trivalent chromium passivation film is prepared using the current trivalent chromium passivation process; e) After the workpiece is passivated with trivalent chromium, a graphene-modified sealing agent is used to prepare a graphene-modified sealing layer.

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