Potassium chloride zinc-iron alloy plating solution and electroplating process

Abstract

The application discloses a potassium chloride zinc-iron alloy plating solution and a plating process, and the plating solution composition and process parameters are as follows: zinc chloride 50-70 g / L, ferrous chloride tetrahydrate 2-12 g / L, potassium chloride 180-220 g / L, boric acid 25-35 g / L, complexing agent 8-40 g / L, brightener 0.1-0.2 mL / L, auxiliary agent 20-30 mL / L, plating solution pH value 4.5-5.6, plating bath temperature 15-30 DEG C, cathode current density 1-3 A / dm 2 , and cathode moving speed 3-5 m / min. The zinc-iron alloy sample prepared by the application and sealed by trivalent chromium blue-white passivation and graphene modified sealing agent has no white rust on the surface after neutral salt spray test for 480 h according to GB / T 10125-2021 "Salt Spray Test for Artificial Atmosphere Corrosion Test", and the plating layer has excellent corrosion resistance.

Description

Technical Field

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

[0002] With the upgrading of my country's industries, electroplating zinc-nickel alloys has largely replaced zinc plating. However, zinc-nickel alloy plating solutions contain complexing agents such as diethylenetriamine, which have high antioxidant properties, posing significant challenges to the treatment of electroplating wastewater. [1] Based on this, the industry is trying to replace zinc-nickel alloy with electroplated zinc-iron alloy in a new process, but so far no new breakthroughs have been achieved.

[0003] Iron is a cost-effective metal that can form high-performance alloys with commonly used metals. In the electroplating industry, basic zinc-iron alloy plating has been widely used. Due to the low iron content in the basic zinc-iron alloy plating solution, the iron mass fraction in the coating is typically 0.3% to 0.7%. [2] Furthermore, its coating performance does not meet the requirements of zinc-nickel alloy coatings. Ferrous ions in acidic zinc-iron alloy plating solutions are easily oxidized to ferric iron by oxygen molecules, forming ferric hydroxide precipitate. This is especially true for chloride-based acidic zinc-iron alloy plating solutions, where ferric hydroxide precipitate will form after standing for 5 days. [3] The application of acidic zinc-iron alloy plating solutions is limited due to their stability issues, and there are currently no reports of mass production applications of electroplating acidic zinc-iron alloys.

[0004] In recent years, hydroxyl graphene-modified sealing agents have been developed that can significantly improve the corrosion resistance and other properties of coatings. The prepared sealing layer has self-healing properties. When used to seal zinc plating layers and zinc-nickel alloy plating layers passivated by trivalent chromium, it overcomes the defect that trivalent chromium passivation films do not have self-healing properties. [4] .

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

[0006] To address the problem of poor stability in acidic zinc-iron alloy plating solutions, this invention provides a potassium chloride zinc-iron alloy plating solution and an electroplating process. To achieve the above objective, this invention employs the following technical solution:

[0007] A potassium chloride zinc-iron alloy plating solution comprises the following components and their contents:

[0008] Zinc chloride 50-70 g / L, ferrous chloride tetrahydrate 2-12 g / L, potassium chloride 180-220 g / L, boric acid 25-35 g / L, complexing agent 8-40 g / L, brightener 0.1-0.2 mL / L, auxiliary agent 20-30 mL / L;

[0009] The ligands include sodium gluconate heptate and sodium sulfosalicylate, with a mass ratio of sodium gluconate heptate to sodium sulfosalicylate of 3:(1-3);

[0010] The brightening agent includes o-chlorobenzaldehyde and formic acid, with a mass ratio of o-chlorobenzaldehyde to formic acid of 1:(0.8-1.2).

[0011] The auxiliary agent includes a sulfonated product of fatty alcohol polyoxyethylene ether and aminosulfonic acid, sodium benzoate, and nicotinic acid, calculated by weight fraction as follows: 17-23 parts of the sulfonated product of fatty alcohol polyoxyethylene ether and aminosulfonic acid, 5-7 parts of sodium benzoate, 0.4-0.6 parts of nicotinic acid, and 80-90 parts of water.

[0012] In some embodiments, the ligand, brightener, and auxiliary agent are formulated using the following method:

[0013] a) The two components are mixed together in a mass ratio of sodium gluconate heptate to sodium sulfosalicylate of 3:(1-3) and stirred evenly to obtain the complexing agent.

[0014] b) Mix the two components together at a mass ratio of o-chlorobenzaldehyde to formic acid of 1:(0.8-1.2) and stir until the solid is dissolved to obtain the brightener;

[0015] c) Add 17-23 kg of the sulfonated product of fatty alcohol polyoxyethylene ether and aminosulfonic acid, 5-7 kg of sodium benzoate, and 0.4-0.6 kg of nicotinic acid to 70 kg of water, stir to dissolve the solids, and add water to 100 L to obtain the aforementioned auxiliary agent.

[0016] In some embodiments, the sulfonated product of fatty alcohol polyoxyethylene ether and aminosulfonic acid is a sulfonated product of fatty alcohol polyoxyethylene ether and aminosulfonic acid with model number OX-105.

[0017] In some embodiments, the pH of the potassium chloride zinc-iron alloy plating solution is 4.5 to 5.6.

[0018] In some embodiments, the potassium chloride zinc-iron alloy plating solution is prepared by the following method:

[0019] a) Add 70% water to the plating tank according to the volume of the plating solution, and add zinc chloride, potassium chloride, boric acid and complexing agent according to the process requirements, and stir to dissolve the above substances;

[0020] b) Add ferrous chloride tetrahydrate according to the process requirements and stir until the solids dissolve;

[0021] c) Add brightener and auxiliary agents according to 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;

[0022] d) At 0.1–0.2 A / dm 2 Electrolysis at current density for 30–90 minutes.

[0023] A potassium chloride zinc-iron alloy electroplating process includes the following components and process parameters:

[0024] Zinc chloride 50–70 g / L, ferrous chloride tetrahydrate 2–12 g / L, potassium chloride 180–220 g / L, boric acid 25–35 g / L, complexing agent 8–40 g / L, brightener 0.1–0.2 mL / L, auxiliary agent 20–30 mL / L, plating bath pH 4.5–5.6, plating bath temperature 15–30℃, cathode current density 1–3 A / dm³ 2 The cathode moves at a speed of 3–5 m / min.

[0025] In some embodiments, the anode is made of zinc plate with a mass fraction of 99.9%.

[0026] In some embodiments, the area ratio of the cathode to the anode is 2:(0.7 to 1.3).

[0027] In some embodiments, a 30% (w / w) solution of ferrous chloride tetrahydrate is added to the plating bath during production to maintain its concentration at 2–12 g / L.

[0028] In some of these embodiments, the plating solution is circulated and filtered during production using a filter.

[0029] In some embodiments, the potassium chloride zinc-iron alloy electroplating process includes the following steps:

[0030] a) Prepare potassium chloride zinc-iron alloy plating solution;

[0031] b) Pre-treat the workpiece using existing pre-treatment methods;

[0032] c) Galvanized iron alloy plating after pretreatment of the workpiece;

[0033] d) After the workpiece is galvanized with iron alloy, a trivalent chromium passivation film is prepared using the current trivalent chromium passivation process;

[0034] e) After the workpiece is passivated with trivalent chromium, a graphene-modified sealing layer is prepared using a graphene-modified sealing agent.

[0035] The beneficial effects of this invention are as follows:

[0036] 1. The potassium chloride zinc-iron alloy plating solution and electroplating process disclosed in this invention use sodium gluconate heptate and sodium sulfosalicylate as complexing agents. Sodium gluconate heptate forms a stable complex ion with ferrous ions, which can effectively inhibit the oxidation of ferrous ions to ferric ions. Sodium sulfosalicylate forms a stable complex ion with a small amount of ferric ions in the plating solution, thereby eliminating its adverse effects.

[0037] 2. The potassium chloride zinc-iron alloy plating solution and electroplating process disclosed in this invention overcome the defects of poor stability of traditional chloride acidic zinc-iron alloy plating solutions.

[0038] 3. The potassium chloride zinc-iron alloy plating solution and electroplating process disclosed in this invention produce zinc-iron alloy coatings with significantly higher salt spray resistance than existing acidic zinc plating coatings.

[0039] 4. The potassium chloride zinc iron alloy plating solution and electroplating process disclosed in this 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-effectiveness of the brightener.

[0040] 5. The potassium chloride zinc-iron alloy plating solution and electroplating process disclosed in this invention have formic acid in the brightener, which has strong reducing properties and inhibits the formation of trivalent iron in the plating solution. Attached Figure Description

[0041] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, do not constitute an undue limitation of the invention. In the drawings:

[0042] Figure 1 This is a schematic diagram of the coating structure in Embodiment 1 of the present invention. Figure 2 This is a schematic diagram of the coating structure in Embodiment 2 of the present invention. Figure 3 This is a schematic diagram of the coating structure in Embodiment 3 of the present invention. Figure 4 This is a schematic diagram of the coating structure in Embodiment 4 of the present invention. Detailed Implementation

[0043] The illustrative embodiments and descriptions described herein are intended to explain the invention in order to better understand it, but are not intended to limit the invention.

[0044] A potassium chloride zinc-iron alloy plating solution and electroplating process includes 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.

[0045] Preferably, the ligand comprises sodium gluconate and sodium sulfosalicylate, wherein the mass ratio of sodium gluconate to sodium sulfosalicylate is 3:(1-3), and the ligand is obtained by mixing the two and stirring evenly.

[0046] Preferably, the brightener includes o-chlorobenzaldehyde and formic acid, with a mass ratio of o-chlorobenzaldehyde to formic acid of 1:(0.8-1.2). The two components are mixed and stirred until the solid is dissolved to obtain the brightener described above.

[0047] The auxiliary agent includes a sulfonated product of fatty alcohol polyoxyethylene ether and aminosulfonic acid, sodium benzoate, and nicotinic acid. 17-23 kg of the sulfonated 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 solids, and then water is added to a final volume of 100 L to obtain the auxiliary agent.

[0048] Preferably, the sulfonated product of fatty alcohol polyoxyethylene ether and aminosulfonic acid is the sulfonated product of fatty alcohol polyoxyethylene ether and aminosulfonic acid with model number OX-105.

[0049] Preferably, the potassium chloride zinc-iron alloy plating solution is prepared according to the following method:

[0050] a) Add 70% water to the plating tank according to the volume of the plating solution, and add zinc chloride, potassium chloride, boric acid and complexing agent according to the process requirements, and stir to dissolve the above substances;

[0051] b) Add ferrous chloride tetrahydrate according to the process requirements and stir until the solids dissolve;

[0052] c) Add brightener and auxiliary agents according to 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;

[0053] d) At 0.1–0.2 A / dm 2 Electrolysis at current density for 30–90 minutes.

[0054] Preferably, the potassium chloride zinc-iron alloy electroplating process includes the following components and process parameters:

[0055] Zinc chloride 50–70 g / L, ferrous chloride tetrahydrate 2–12 g / L, potassium chloride 180–220 g / L, boric acid 25–35 g / L, complexing agent 8–40 g / L, brightener 0.1–0.2 mL / L, auxiliary agent 20–30 mL / L, plating bath pH 4.5–5.6, plating bath temperature 15–30℃, cathode current density 1–3 A / dm³ 2 The cathode moves at a speed of 3-5 m / min, and the anode is made of zinc plate with a mass fraction of 99.9%. The area ratio of the cathode to the anode is 2:(0.7-1.3).

[0056] Preferably, during production, a 30% (w / w) ferrous chloride tetrahydrate solution is added to the plating bath to maintain its concentration at 2–12 g / L.

[0057] Preferably, the plating solution is circulated and filtered during production using a filter.

[0058] Preferably, the potassium chloride zinc-iron alloy electroplating process includes the following steps:

[0059] a) Prepare potassium chloride zinc-iron alloy plating solution;

[0060] b) Pre-treat the workpiece using existing pre-treatment methods;

[0061] c) Galvanized iron alloy plating after pretreatment of the workpiece;

[0062] d) After the workpiece is galvanized with iron alloy, a trivalent chromium passivation film is prepared using the current trivalent chromium passivation process;

[0063] e) After the workpiece is passivated with trivalent chromium, a graphene-modified sealing layer is prepared using a graphene-modified sealing agent.

[0064] Plating zinc-iron alloys on aluminum alloy parts also includes a chemical zinc plating process to prepare a chemical zinc plating layer on the aluminum alloy surface.

[0065] Preferably, the trivalent chromium passivation film is prepared using the TRIROS 348 zinc-iron blue-white passivation process from Chaobang Chemical Co., Ltd.

[0066] TRIROS 348 zinc-iron blue-white passivating agent 135-175 mL / L, passivation solution pH 1.8-2.6, operating temperature 30-60℃, immersion time 30-60 s, air agitation.

[0067] Preferably, the graphene-modified sealing layer is prepared using PRODICO 480 graphene-modified sealing agent developed by Chaobang Chemical.

[0068] Prepare a sealing solution by diluting PRODICO 480 graphene modified sealant with water to a ratio of 2.5 to 3.2. Immerse the plated parts in the sealing solution for 8 to 15 seconds, drain them after removal from the tank, and blow off any residual sealing solution on the surface of the plated parts with high-pressure air. After sealing, dry and cure the parts at 70 to 85°C for 20 to 35 minutes.

[0069] Preferably, the chemical zinc plating layer is prepared using the ALBUME AS-699 cyanide-free aluminum zinc plating process from Chaobang Chemical Co., Ltd.

[0070] ALBUME AS-699 cyanide-free aluminum zinc precipitation agent, 150-170 mL / L, with zinc ions in the working solution containing 6-9 g / L and copper ions in the working solution, operating temperature 20℃-30℃, zinc precipitation time 60-120 s.

[0071] Example 1:

[0072] A potassium chloride zinc-iron alloy plating solution and electroplating process includes 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.

[0073] 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 sequentially prepared from the inside to the outside on the steel substrate 01.

[0074] 1. Preparation of zinc-iron alloy electroplating additives:

[0075] The zinc-iron alloy electroplating additives include complexing agents, brighteners, and auxiliary agents.

[0076] 1) Preparation of the complexing agent:

[0077] Sodium gluconate and sodium sulfosalicylate were mixed together in a mass ratio of 3:2 and stirred until homogeneous to obtain the complexing agent.

[0078] 2) Preparation of brightening agent:

[0079] o-chlorobenzaldehyde and formic acid were mixed in a mass ratio of 1:1 and stirred until the solid was dissolved to obtain the above-mentioned brightening agent;

[0080] 3) Preparation of auxiliary agents:

[0081] Add 20 kg of sulfonated product of fatty alcohol polyoxyethylene ether and aminosulfonic acid (model OX-105) produced by Jihechang, 6 kg of sodium benzoate, and 0.5 kg of nicotinic acid to 70 kg of water, stir to dissolve the solids, and add water to 100 L to obtain the aforementioned auxiliary agent.

[0082] 4) Preparation of potassium chloride zinc-iron alloy plating solution:

[0083] The potassium chloride zinc-iron alloy plating solution is prepared according to the following method:

[0084] a) Add 70% water to the plating tank according to the volume of the plating solution, and add zinc chloride, potassium chloride, boric acid and complexing agent according to the process requirements, and stir to dissolve the above substances;

[0085] b) Add ferrous chloride tetrahydrate according to the process requirements and stir until the solids dissolve;

[0086] c) Add brightener and auxiliary agents according to process requirements, stir evenly, adjust the pH of the plating solution to 5 with 10% sodium hydroxide solution or 3% hydrochloric acid, and add water to the specified volume;

[0087] d) At 0.15A / dm 2 Electrolysis at current density for 60 minutes.

[0088] 2. Pretreatment:

[0089] The current pretreatment process is used to process the steel substrate 01 as follows: "chemical degreasing → water washing → pickling → water washing → alkaline cathodic electrolytic degreasing → water washing → alkaline anodic electrolytic degreasing → water washing → activation → water washing".

[0090] 3. Galvanized iron alloy:

[0091] After pretreatment of steel parts, zinc-iron alloy coating 02 is prepared using the potassium chloride zinc-iron alloy electroplating process of the present invention, with a coating thickness of 12μm.

[0092] Zinc chloride 60 g / L, ferrous chloride tetrahydrate 10 g / L, potassium chloride 200 g / L, boric acid 30 g / L, complexing agent 35 g / L, brightener 0.15 mL / L, auxiliary agent 25 mL / L, plating solution pH 5, plating tank temperature 20℃, cathode current density 2 A / dm³ 2 The cathode moves at a speed of 4 m / min, and the anode is made of zinc plate with a mass fraction of 99.9%. The area ratio of the cathode to the anode is 2:1. The plating solution is circulated and filtered during production. A 30% ferrous chloride tetrahydrate solution is added to the plating tank during production to maintain its mass concentration at the required level.

[0093] 4. Passivation:

[0094] After galvanizing the steel parts with iron alloy, a trivalent chromium blue-white passivation film 03 is prepared using the TRIROS 348 zinc-iron blue-white passivation process from Chaobang Chemical.

[0095] TRIROS 348 zinc-iron blue-white passivating agent 150mL / L, passivation solution pH 2.4, operating temperature 45℃, immersion time 45s, air agitation.

[0096] The specific process is as follows: 0.2% sulfuric acid to remove the film → water washing → passivation → water washing.

[0097] 5. Enclosed:

[0098] After passivation of steel parts, a graphene-modified sealing layer 04 was prepared using PRODICO 480 graphene-modified sealing agent developed by Chaobang Chemical.

[0099] Prepare a sealing solution by diluting PRODICO 480 graphene-modified sealant with water to a ratio of 2.8. Immerse the plated parts in the sealing solution for 10 seconds, drain them after removal from the tank, and blow off the residual sealing solution on the surface of the plated parts with high-pressure air. After sealing, dry and cure at 80°C for 25 minutes.

[0100] Example 2:

[0101] A potassium chloride zinc-iron alloy plating solution and electroplating process includes 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.

[0102] 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 sequentially prepared from the inside to the outside on the zinc alloy substrate 11.

[0103] 1. Preparation of zinc-iron alloy electroplating additives:

[0104] The zinc-iron alloy electroplating additives include complexing agents, brighteners, and auxiliary agents.

[0105] 1) Preparation of the complexing agent:

[0106] Sodium gluconate and sodium sulfosalicylate were mixed together in a mass ratio of 3:2 and stirred until homogeneous to obtain the complexing agent.

[0107] 2) Preparation of brightening agent:

[0108] o-chlorobenzaldehyde and formic acid were mixed in a mass ratio of 1:1 and stirred until the solid was dissolved to obtain the above-mentioned brightening agent;

[0109] 3) Preparation of auxiliary agents:

[0110] Add 20 kg of sulfonated product of fatty alcohol polyoxyethylene ether and aminosulfonic acid (model OX-105) produced by Jihechang, 6 kg of sodium benzoate, and 0.5 kg of nicotinic acid to 70 kg of water, stir to dissolve the solids, and add water to 100 L to obtain the aforementioned auxiliary agent.

[0111] 4) Preparation of potassium chloride zinc-iron alloy plating solution:

[0112] The potassium chloride zinc-iron alloy plating solution is prepared according to the following method:

[0113] a) Add 70% water to the plating tank according to the volume of the plating solution, and add zinc chloride, potassium chloride, boric acid and complexing agent according to the process requirements, and stir to dissolve the above substances;

[0114] b) Add ferrous chloride tetrahydrate according to the process requirements and stir until the solids dissolve;

[0115] c) Add brightener and auxiliary agents according to 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;

[0116] d) at 0.15A / dm 2 Electrolyze for 60 minutes at the current density.

[0117] 2. Pretreatment:

[0118] The zinc alloy die-casting substrate 11 is subjected to the following pretreatment process: "chemical dewaxing → water washing → ultrasonic dewaxing → water washing → ultrasonic degreasing → water washing → activation → water washing".

[0119] 3. Galvanized iron alloy:

[0120] After pretreatment, zinc alloy die-casting parts are coated with zinc-iron alloy using the potassium chloride zinc-iron alloy electroplating process of the present invention, with a coating thickness of 16 μm.

[0121] Zinc chloride 70 g / L, ferrous chloride tetrahydrate 10 g / L, potassium chloride 220 g / L, boric acid 35 g / L, complexing agent 40 g / L, brightener 0.15 mL / L, auxiliary agent 25 mL / L, plating solution pH 4.6, plating tank temperature 25℃, cathode current density 2 A / dm³ 2 The cathode moves at a speed of 4 m / min, and the anode is made of zinc plate with a mass fraction of 99.9%. The area ratio of the cathode to the anode is 2:1. The plating solution is circulated and filtered during production. A 30% ferrous chloride tetrahydrate solution is added to the plating tank during production to maintain its mass concentration at the required level.

[0122] 4. Passivation:

[0123] After zinc alloy die castings are plated with zinc-iron alloy, trivalent chromium blue-white passivation film 13 is prepared using the TRIROS 348 zinc-iron blue-white passivation process of Chaobang Chemical.

[0124] TRIROS 348 zinc-iron blue-white passivating agent 175mL / L, passivation solution pH 2.4, operating temperature 40℃, immersion time 40s, air agitation.

[0125] The specific process is as follows: 0.2% sulfuric acid to remove the film → water washing → passivation → water washing.

[0126] 5. Enclosed:

[0127] After passivation, the zinc alloy die casting was prepared with a graphene-modified sealing layer 14 using PRODICO 480 graphene-modified sealing agent developed by Chaobang Chemical.

[0128] Prepare a sealing solution by diluting PRODICO 480 graphene-modified sealant with water to a ratio of 2.8. Immerse the plated parts in the sealing solution for 10 seconds, drain them after removal from the tank, and blow off the residual sealing solution on the surface of the plated parts with high-pressure air. After sealing, dry and cure at 85°C for 20 minutes.

[0129] Example 3:

[0130] A potassium chloride zinc-iron alloy plating solution and electroplating process includes 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.

[0131] 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 sequentially prepared from the inside to the outside on the cast iron substrate 21.

[0132] 1. Preparation of zinc-iron alloy electroplating additives:

[0133] The zinc-iron alloy electroplating additives include complexing agents, brighteners, and auxiliary agents.

[0134] 1) Preparation of the complexing agent:

[0135] Sodium gluconate and sodium sulfosalicylate were mixed together in a mass ratio of 3:2 and stirred until homogeneous to obtain the complexing agent.

[0136] 2) Preparation of brightening agent:

[0137] o-chlorobenzaldehyde and formic acid were mixed in a mass ratio of 1:1 and stirred until the solid was dissolved to obtain the above-mentioned brightening agent;

[0138] 3) Preparation of auxiliary agents:

[0139] Add 20 kg of sulfonated product of fatty alcohol polyoxyethylene ether and aminosulfonic acid (model OX-105) produced by Jihechang, 6 kg of sodium benzoate, and 0.5 kg of nicotinic acid to 70 kg of water, stir to dissolve the solids, and add water to 100 L to obtain the aforementioned auxiliary agent.

[0140] 4) Preparation of potassium chloride zinc-iron alloy plating solution:

[0141] The potassium chloride zinc-iron alloy plating solution is prepared according to the following method:

[0142] a) Add 70% water to the plating tank according to the volume of the plating solution, and add zinc chloride, potassium chloride, boric acid and complexing agent according to the process requirements, and stir to dissolve the above substances;

[0143] b) Add ferrous chloride tetrahydrate according to the process requirements and stir until the solids dissolve;

[0144] c) Add brightener and auxiliary agents according to 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;

[0145] d) at 0.1A / dm 2 Electrolyze for 90 minutes at the current density.

[0146] 2. Pretreatment:

[0147] The existing pretreatment process is used to perform the following steps on the cast iron substrate 21: "chemical degreasing → water washing → pickling → water washing → alkaline cathodic electrolytic degreasing → water washing → alkaline anodic electrolytic degreasing → water washing → activation → water washing".

[0148] 3. Galvanized iron alloy:

[0149] After pretreatment of the cast iron parts, a zinc-iron alloy coating 22 is prepared using the potassium chloride zinc-iron alloy electroplating process of the present invention, with a coating thickness of 16μm.

[0150] Zinc chloride 50 g / L, ferrous chloride tetrahydrate 8 g / L, potassium chloride 180 g / L, boric acid 25 g / L, complexing agent 25 g / L, brightener 0.15 mL / L, auxiliary agent 25 mL / L, plating solution pH 5.3, plating tank temperature 23℃, cathode current density 2 A / dm³ 2 The cathode moves at a speed of 4 m / min, and the anode is made of zinc plate with a mass fraction of 99.9%. The area ratio of the cathode to the anode is 2:1. The plating solution is circulated and filtered during production. A 30% ferrous chloride tetrahydrate solution is added to the plating tank during production to maintain its mass concentration at the required level.

[0151] 4. Passivation:

[0152] After galvanizing the cast iron parts with iron alloy, a trivalent chromium blue-white passivation film was prepared using the TRIROS 348 zinc-iron blue-white passivation process from Chaobang Chemical.

[0153] TRIROS 348 zinc-iron blue-white passivating agent 135mL / L, passivation solution pH 2.0, operating temperature 50℃, immersion time 45s, air agitation.

[0154] The specific process is as follows: 0.2% sulfuric acid to remove the film → water washing → passivation → water washing.

[0155] 5. Enclosed:

[0156] After passivation of the cast iron parts, a graphene-modified sealing layer 24 was prepared using PRODICO 480 graphene-modified sealing agent developed by Chaobang Chemical.

[0157] Prepare a sealing solution by diluting PRODICO 480 graphene-modified sealant with water to a ratio of 2.8. Immerse the plated parts in the sealing solution for 10 seconds, drain them after removal from the tank, and blow off any remaining sealing solution from the surface of the plated parts with high-pressure air. After sealing, dry and cure at 70°C for 35 minutes.

[0158] Example 4:

[0159] A potassium chloride zinc-iron alloy plating solution and electroplating process includes 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.

[0160] 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 plating layer 2, a zinc-iron alloy coating layer 3, a trivalent chromium blue-white passivation film 4, and a graphene modified sealing layer 5, which are sequentially prepared from the inside to the outside on the aluminum alloy substrate 1.

[0161] 1. Preparation of zinc-iron alloy electroplating additives:

[0162] The zinc-iron alloy electroplating additives include complexing agents, brighteners, and auxiliary agents.

[0163] 1) Preparation of the complexing agent:

[0164] Sodium gluconate and sodium sulfosalicylate were mixed together in a mass ratio of 3:2 and stirred until homogeneous to obtain the complexing agent.

[0165] 2) Preparation of brightening agent:

[0166] o-chlorobenzaldehyde and formic acid were mixed in a mass ratio of 1:1 and stirred until the solid was dissolved to obtain the above-mentioned brightening agent;

[0167] 3) Preparation of auxiliary agents:

[0168] Add 20 kg of sulfonated product of fatty alcohol polyoxyethylene ether and aminosulfonic acid (model OX-105) produced by Jihechang, 6 kg of sodium benzoate, and 0.5 kg of nicotinic acid to 70 kg of water, stir to dissolve the solids, and add water to 100 L to obtain the aforementioned auxiliary agent.

[0169] 4) Preparation of potassium chloride zinc-iron alloy plating solution:

[0170] The potassium chloride zinc-iron alloy plating solution is prepared according to the following method:

[0171] a) Add 70% water to the plating tank according to the volume of the plating solution, and add zinc chloride, potassium chloride, boric acid and complexing agent according to the process requirements, and stir to dissolve the above substances;

[0172] b) Add ferrous chloride tetrahydrate according to the process requirements and stir until the solids dissolve;

[0173] c) Add brightener and auxiliary agents according to 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;

[0174] d) at 0.2A / dm 2 Electrolyze for 30 minutes at the current density.

[0175] 2. Pretreatment:

[0176] The current pretreatment process is used to process the aluminum alloy substrate 1 as follows: "chemical degreasing → water washing → ultrasonic degreasing → water washing → alkaline etching → water washing → brightening → water washing → micro-etching → water washing".

[0177] 3. Chemical zinc precipitation:

[0178] After pretreatment, the aluminum alloy parts were prepared with a chemical zinc coating using the ALBUME AS-699 cyanide-free aluminum zinc deposition process from Chaobang Chemical.

[0179] 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.

[0180] The specific process flow is as follows: first chemical zinc precipitation → water washing → zinc stripping → water washing → second chemical zinc precipitation → water washing.

[0181] 4. Galvanized iron alloy:

[0182] After chemical zinc immersion, zinc-iron alloy coating 3 is prepared using the potassium chloride zinc-iron alloy electroplating process of the present invention, with a coating thickness of 12μm.

[0183] Zinc chloride 65 g / L, ferrous chloride tetrahydrate 11 g / L, potassium chloride 210 g / L, boric acid 30 g / L, complexing agent 37 g / L, brightener 0.15 mL / L, auxiliary agent 25 mL / L, plating bath pH 5.4, plating tank temperature 25℃, cathode current density 2 A / dm³ 2 The cathode moves at a speed of 4 m / min, and the anode is made of zinc plate with a mass fraction of 99.9%. The area ratio of the cathode to the anode is 2:1. The plating solution is circulated and filtered during production. A 30% ferrous chloride tetrahydrate solution is added to the plating tank during production to maintain its mass concentration at the required level.

[0184] 5. Passivation:

[0185] After zinc-iron alloy plating, the aluminum alloy parts are treated with the TRIROS 348 zinc-iron blue-white passivation process of Chaobang Chemical to prepare a trivalent chromium blue-white passivation film.

[0186] TRIROS 348 zinc-iron blue-white passivating agent 160mL / L, passivation solution pH 2.2, operating temperature 50℃, immersion time 35s, air agitation.

[0187] The specific process is as follows: 0.2% sulfuric acid to remove the film → water washing → passivation → water washing.

[0188] 6. Enclosed:

[0189] After passivation of aluminum alloy parts, a graphene-modified sealing layer was prepared using PRODICO 480 graphene-modified sealing agent developed by Chaobang Chemical.

[0190] Prepare a sealing solution by diluting PRODICO 480 graphene-modified sealant with water to a ratio of 2.8. Immerse the plated parts in the sealing solution for 10 seconds, drain them after removal from the tank, and blow off the residual sealing solution on the surface of the plated parts with high-pressure air. After sealing, dry and cure at 75°C for 30 minutes.

[0191] Experimental Example 1:

[0192] The galvanized iron alloy samples prepared in Examples 1 to 4 showed no white rust after 480 hours of neutral salt spray testing according to GB / T 10125–2021 "Artificial Atmosphere Corrosion Test - Salt Spray Test". The salt spray resistance of the coating prepared by this invention is far superior to the requirement of 216 hours of no white rust as specified in GB-T 41950-2022 "Metallic Coatings - Electroplating of Zinc and Zinc Alloys on Steel without Hexavalent Chromium Treatment".

[0193] Experimental Example 2:

[0194] 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 Coatings on Metallic Substrates". Steel and cast iron samples were heated to 250°C and held for 30 minutes in a furnace; zinc alloy samples were heated to 150°C and held for 30 minutes; and aluminum alloy samples were heated to 220°C and held for 30 minutes. After heating, the samples were immediately removed and cooled in room temperature water. No blistering or peeling of the coating occurred. The tests show that the coating structure prepared by this invention has good adhesion.

[0195] Experimental Example 3:

[0196] 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 "Met Test Methods for Military Equipment Laboratory Environment - Part 10: Mold Test". No mold was generated on the surface of the samples, which met the environmental test requirements.

[0197] Experimental Example 4:

[0198] A 1000 mL potassium chloride-zinc-iron alloy plating bath was prepared, comprising 70 g / L zinc chloride, 12 g / L ferrous chloride tetrahydrate, 220 g / L potassium chloride, 35 g / L boric acid, 35 g / L complexing agent, 0.2 mL / L brightener, and 30 mL / L auxiliary agent. The pH of the plating bath was 5.6. After the plating bath was placed in the laboratory for one month, no precipitate was formed.

[0199] Experimental Example 5:

[0200] The potassium chloride zinc-iron alloy plating solution prepared in Example 4 was used to continuously conduct 250 mL Hull cell tests. One test piece was plated at 1 A current for 10 minutes. Brightener, auxiliary agent, complexing agent, ferrous chloride, and potassium chloride were added according to the changes observed in the test pieces. A total of 120 test pieces were plated. No ferric hydroxide precipitate appeared in the plating solution, the plating solution had good coverage, the coating was bright, and there was no significant change in the appearance of the coating during continuous electroplating.

[0201] Comparative Example 1:

[0202] Following the process flow of Example 1, the zinc plating process of the iron alloy in this example was replaced by the ZINLITE 401 potassium chloride zinc plating process from Chaobang Chemical. Zinc plating, trivalent chromium blue-white passivation, and graphene-modified sealing agent were sequentially applied to the steel parts. A neutral salt spray test was conducted according to GB / T 10125–2021 "Artificial Atmosphere Corrosion Test - Salt Spray Test". No white rust was observed on the surface of the prepared zinc-plated samples after 320 hours.

[0203] The technical solutions provided by the embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the embodiments of the present invention. The descriptions of the embodiments above are only for helping to understand the principles of the embodiments of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these should all fall within the protection scope of the present invention.

Claims

1. A potassium chloride zinc-iron alloy plating solution, characterized in that, Includes the following components and their contents: Zinc chloride 50-70 g / L, ferrous chloride tetrahydrate 2-12 g / L, potassium chloride 180-220 g / L, boric acid 25-35 g / L, complexing agent 8-40 g / L, brightener 0.1-0.2 mL / L, auxiliary agent 20-30 mL / L; The ligands include sodium gluconate heptate and sodium sulfosalicylate, with a mass ratio of sodium gluconate heptate to sodium sulfosalicylate of 3:(1-3); The brightening agent includes o-chlorobenzaldehyde and formic acid, with a mass ratio of o-chlorobenzaldehyde to formic acid of 1:(0.8-1.2). The auxiliary agent, calculated by weight, includes 17-23 parts of the sulfonated product of fatty alcohol polyoxyethylene ether and aminosulfonic acid, 5-7 parts of sodium benzoate, 0.4-0.6 parts of nicotinic acid, and 80-90 parts of water. The pH of the potassium chloride zinc-iron alloy plating solution is 4.5 to 5.

6.

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

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

4. The potassium chloride zinc-iron alloy plating solution according to claim 1, characterized in that, The plating solution is prepared according to the following method: a) Add 70% water to the plating tank according to the volume of the plating solution, and 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 solids dissolve; c) Add brightener and auxiliary agents according to 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 0.1–0.2 A / dm 2 Electrolysis at current density for 30–90 minutes.

5. A potassium chloride zinc-iron alloy electroplating process, characterized in that, The potassium chloride zinc-iron alloy plating bath includes 50-70 g / L zinc chloride, 2-12 g / L ferrous chloride tetrahydrate, 180-220 g / L potassium chloride, 25-35 g / L boric acid, 8-40 g / L complexing agent, 0.1-0.2 mL / L brightener, 20-30 mL / L auxiliary agent, and a pH value of 4.5-5.

6. The ligands include sodium gluconate heptate and sodium sulfosalicylate, with a mass ratio of sodium gluconate heptate to sodium sulfosalicylate of 3:(1-3); The brightening agent includes o-chlorobenzaldehyde and formic acid, with a mass ratio of o-chlorobenzaldehyde to formic acid of 1:(0.8-1.2). The auxiliary agent, calculated by weight, consists of 17-23 parts of the sulfonated product of fatty alcohol polyoxyethylene ether and aminosulfonic acid, 5-7 parts of sodium benzoate, 0.4-0.6 parts of nicotinic acid, and 80-90 parts of water. Electroplating process parameters: plating bath temperature 15~30℃, cathode current density 1~3A / dm³ 2 The cathode moves at a rate of 3–5 m / min.

6. The potassium chloride zinc-iron alloy electroplating process according to claim 5, characterized in that: The anode is made of zinc plate with a mass fraction of 99.9%.

7. The potassium chloride zinc-iron alloy electroplating process according to claim 5, characterized in that: The area ratio of the cathode to the anode is 2:(0.7 to 1.3).

8. The potassium chloride zinc-iron alloy electroplating process according to claim 5, characterized in that: During production, a 30% (w / w) ferrous chloride tetrahydrate solution is added to the plating bath to maintain its concentration at 2–12 g / L.

9. The potassium chloride zinc-iron alloy electroplating process according to claim 5, characterized in that, The process includes the following steps: a) Prepare the potassium chloride zinc-iron alloy plating solution; b) Perform pretreatment on the workpiece; c) Galvanized iron alloy plating after pretreatment of the workpiece; d) After the workpiece is galvanized with iron alloy, a trivalent chromium passivation film is prepared using a trivalent chromium passivation process; e) After the workpiece is passivated with trivalent chromium, a graphene-modified sealing layer is prepared using a graphene-modified sealing agent.

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