Cyanide-free cadmium-iron alloy plating process for high-strength structural steel

Abstract

The invention discloses a cyanide-free cadmium-iron alloy plating process for high-strength structural steel. The cyanide-free cadmium-iron alloy plating process comprises the step that a nickel-titanium alloy plating layer, a cyanide-free cadmium-iron alloy plating layer and a hexavalent chromium passivation film are sequentially prepared on a high-strength structural steel substrate from inside to outside. The prepared sample piece is subjected to a hydrogen brittleness test according to HB 5067.1-2005 Part 1 of hydrogen brittleness test of plating process: Mechanical Method, and the test result meets the standard requirement; the surface of a plated part is free of white rust after being subjected to an acetate mist test for 400h according to GB / T 10125-2021 Artificial Atmosphere Corrosion Test Salt Spray Test, and a plating layer of the plated part has excellent corrosion resistance; according to GB / T 5270-2005 < GB / T 5270-2005 < GB / T > 5270-2005 < GB / T > 5270-2005 > < GB / T > 5270-2005 > < GB / T > 5270-2005 > < GB / T > 5270-2005 > < GB /

Description

Technical Field

[0001] The invention belongs to the technical field of metal surface treatment, and in particular relates to a cyanide-free cadmium iron alloy plating process for high-strength structural steel. Background Art

[0002] The aviation industry extensively utilizes high-strength structural materials to manufacture components. These materials are highly sensitive to hydrogen embrittlement and prone to stress corrosion cracking. Therefore, avoiding hydrogen embrittlement is a crucial consideration during the processing and use of high-strength structural steel. Electroplated cadmium-titanium alloys offer excellent corrosion resistance, low hydrogen embrittlement, and a simple process, making them particularly suitable for the production of protective coatings for high-strength structural steels in the aviation industry. The current cadmium-titanium alloy electroplating process typically involves direct electroplating of the alloy onto a high-strength structural steel substrate, followed by hexavalent chromium passivation. While cyanide-based cadmium-titanium alloy plating is commonly used abroad, the nitrilotriacetic acid-ammonium chloride plating process is generally used in China. A100 steel (23Co14Ni12Cr3Mo) is a highly tough, secondary-hardening, ultra-high-strength structural steel widely used in load-bearing components within the aviation industry, offering excellent application prospects. Experimental studies of cadmium-titanium alloy electroplating on A100 steel components have shown that the majority of the hydrogen in the electroplated cadmium-titanium alloy specimens resides in the coating, with only a minimal amount penetrating into the substrate. [2] It is generally believed that the titanium in the cadmium-titanium alloy coating can combine with hydrogen to form TiH3, which can effectively prevent the penetration of hydrogen into the high-strength structural steel matrix.

[0003] However, both cyanide cadmium titanium alloy plating and cyanide-free cadmium titanium alloy plating have the problem of poor bath stability. [3] , it is difficult to maintain the plating solution and the coating quality is not stable enough.

[0004] References: [1]. Naval 4805 Factory, Beijing University of Aeronautics and Astronautics, 621 Institute, etc., Effect of Cyanide-free Electroplating of Cadmium-Titanium Alloy on Hydrogen Embrittlement of Steel Matrix [J], Aviation Technology, 1980, 23(18): 29-34. [2]. Yu Bo, Tang Zhihui, Peng Chao, etc., Effect of Cyanide-free Electroplating of Cadmium-Titanium Alloy on Hydrogen Embrittlement of Steel Matrix [J], Electroplating and Finishing, 2011, 33(11): 1-4. [3]. Lin Xi, Study on Cyanide-free Electroplating Process and Electrodeposition Behavior of Cadmium-Titanium Alloy [D], Nanchang, Nanchang Hangkong University, 2018. Summary of the Invention

[0005] In order to solve the problem of poor plating solution stability faced by direct cadmium titanium alloy plating on high-strength structural steel substrates, the present invention provides a cyanide-free cadmium iron alloy plating process for high-strength structural steel. To achieve the above-mentioned purpose, the present invention adopts the following technical solutions: A cyanide-free cadmium iron alloy plating process for high-strength structural steel includes the following processes: (1) Pretreatment of high-strength structural steel, including sandblasting, degreasing, and sulfuric acid anode electrolytic activation; (2) After pre-treatment of high-strength structural steel, nickel-titanium alloy coating is prepared by nickel-titanium alloy plating process; (3) High-strength structural steel is plated with nickel-titanium alloy and then the cyanide-free cadmium iron alloy coating is prepared by potassium chloride cadmium iron alloy plating process; (4) High-strength structural steel is subjected to dehydrogenation treatment after potassium chloride cadmium iron alloy; (5) After dehydrogenation, the high-strength structural steel is subjected to the current passivation process to prepare the passivation film; The potassium chloride cadmium iron alloy plating process includes the following components and process parameters: Cadmium chloride 25-35 g / L, ferrous chloride tetrahydrate 4-6 g / L, potassium chloride 100-140 g / L, complexing agent 100-140 g / L, leveling agent 1.5-2.5 mL / L, brightener 1.5-2.5 mL / L, auxiliary agent 25-30 mL / L, stabilizer 25-35 g / L, plating solution pH 6-8, plating tank temperature 20-35 ° C, cathode current density 0.5-1.5 A / dm 2 , the cathode moves 2 to 4 m / min.

[0006] The leveling agent includes 5-10 g / L of trimercapto-s-triazine, 30-60 g / L of an organic amine epoxy derivative with the model number of GDX, and 5-10 g / L of sodium hydroxide; The stabilizer comprises sodium glucoheptanoate and sodium hydrogen succinate, and the mass ratio of sodium glucoheptanoate to sodium hydrogen succinate is 1:(2-3); The complexing agent includes nitrilotriacetic acid, sulfosalicylic acid, and malic acid, wherein the mass ratio of nitrilotriacetic acid, sulfosalicylic acid, and malic acid is 3:(1-2):(4-6), and the above components are uniformly mixed to obtain the complexing agent; The brightener comprises three components, A, B and C. Component A comprises α-vinyl-N-propanesulfonic acid pyridine inner salt; component B comprises any one or two of 3-methoxy-4-hydroxybenzaldehyde, 3,4-dimethoxybenzaldehyde and 4-methoxybenzaldehyde; and component C comprises any one or two of propargyl alcohol ethoxy ether, propargyl alcohol propoxy ether, N,N-diethylpropargylamine, N,N-diethylpropargylamine formate and N,N-diethylpropargylamine sulfate. 30 kg of isopropyl alcohol is added to 40 kg of water and mixed evenly. 3-8 kg of component A, 3-5 kg ​​of component B and 6-10 kg of component C are added, stirred to dissolve, and water is added to 100 L to obtain the brightener.

[0007] The auxiliary agent includes polyacrylamide with a molecular weight less than 8000, sodium salt of 2-ethylhexyl sulfate, a condensate of ethylenediamine or dimethylpropylamine and epichlorohydrin, and component D, wherein component D is the same as component C in the brightener. 5-8 kg of polyacrylamide with a molecular weight less than 8000, 2-5 kg ​​of condensate of ethylenediamine or dimethylpropylamine and epichlorohydrin, 3-8 kg of sodium salt of 2-ethylhexyl sulfate, and 3-6 kg of component D are added to 70 kg of water, stirred to dissolve, and water is added to 100 L to obtain the auxiliary agent.

[0008] In some embodiments, the anode is made of a cadmium plate having a mass fraction of 99.97%.

[0009] In some embodiments, the area ratio of the cathode to the anode is 2:(0.7-1.3).

[0010] 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 4-6 g / L.

[0011] In some embodiments, the nickel-titanium alloy plating process adopts the NT-770 nickel-titanium alloy plating process, including the following components and process parameters: Nickel sulfate hexahydrate 50-60g / L, nickel chloride hexahydrate 5-15g / L, titanyl sulfate 5-15g / L, boric acid 30-40g / L, trisodium citrate 50-60g / L, succinimidyl 8-12g / L, NT-770 brightener 2-4mL / L, NT-770 auxiliary agent 8-12mL / L, plating solution pH 3.5-5.0, plating tank temperature 50-60℃, cathode current density 0.6-1.2A / dm 2 , air stirring.

[0012] In some embodiments, the high-strength structural steel substrate pretreatment includes: sandblasting, alkaline chemical degreasing, alkaline anodic electrolytic degreasing, and sulfuric acid anodic electrolytic activation.

[0013] In some embodiments, the sulfuric acid anode electrolytic activation comprises the following components and process parameters: Sulfuric acid 100-200g / L, operating at room temperature, with the workpiece to be plated as the anode and the titanium plate as the cathode, the anode current density is 1-2A / dm 2 , electrolysis for 20 to 60 seconds.

[0014] In some embodiments, the thickness of the nickel-titanium alloy coating is 4-8 μm.

[0015] In some embodiments, the thickness of the cyanide-free cadmium iron alloy coating is 6 to 22 μm.

[0016] In some embodiments, the passivation film is prepared using a hexavalent chromium passivation process.

[0017] The titanium in the coating has the property of blocking the diffusion of hydrogen into the high-strength structural steel substrate. Therefore, a nickel-titanium alloy coating is first deposited on the high-strength structural steel substrate, followed by a cadmium-iron alloy coating. During the electroplating process, the titanium in the nickel-titanium alloy coating blocks the diffusion of hydrogen into the substrate, effectively preventing hydrogen embrittlement. The cadmium-iron alloy coating is anodic relative to the nickel-titanium alloy coating, and this coating structure provides electrochemical protection.

[0018] Compared with the prior art, the present invention has the following beneficial effects: 1. The cyanide-free cadmium-iron alloy plating process for high-strength structural steel disclosed in the present invention is to plate nickel-titanium alloy on the high-strength structural steel substrate and then plate cadmium-iron alloy. The titanium in the nickel-titanium alloy coating can effectively prevent the diffusion of hydrogen elements toward the substrate, thereby avoiding hydrogen embrittlement of the high-strength structural steel substrate.

[0019] 2. The cyanide-free cadmium-iron alloy plating process for high-strength structural steel disclosed in the present invention plates cadmium on the nickel-titanium alloy coating. The cadmium-iron alloy coating has an electrochemical protective effect on the nickel-titanium alloy coating. This coating structure can effectively prevent the corrosive medium from eroding toward the substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings described herein are used to provide a further understanding of the present invention, constitute a part of this application, and do not constitute an improper limitation of the present invention. In the drawings: Figure 1 Schematic diagram of the coating structure prepared in Example 1, Example 2, Example 3, and Example 4 of the present invention. DETAILED DESCRIPTION

[0021] The present invention will be described in detail below with reference to 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.

[0022] A cyanide-free cadmium-iron alloy plating process for high-strength structural steel comprises pre-treatment of the high-strength structural steel and sequential preparation of a nickel-titanium alloy coating, a cyanide-free cadmium-iron alloy coating, and a passivation film on a substrate of the high-strength structural steel from the inside out.

[0023] The surface of the high-strength structural steel workpiece is sandblasted, degreased, and activated by sulfuric acid anodic electrolysis.

[0024] Preferably, the sulfuric acid anode electrolytic activation adopts the following process: Sulfuric acid 100-200g / L, operating at room temperature, with the workpiece to be plated as the anode and the titanium plate as the cathode, the anode current density is 1-2A / dm2 , electrolysis for 20 to 60 seconds.

[0025] After pre-treatment of the high-strength structural steel workpiece, the nickel-titanium alloy coating is prepared by the current nickel-titanium alloy plating process.

[0026] Preferably, the nickel-titanium alloy coating has a thickness of 4 to 8 μm and is prepared using the NT-770 nickel-titanium alloy plating process of Chaobang Chemical: Nickel sulfate hexahydrate 50-60g / L, nickel chloride hexahydrate 5-15g / L, titanyl sulfate 5-15g / L, boric acid 30-40g / L, trisodium citrate 50-60g / L, succinimidyl 8-12g / L, NT-770 brightener 2-4mL / L, NT-770 auxiliary agent 8-12mL / L, plating solution pH 3.5-5.0, plating tank temperature 50-60℃, cathode current density 0.6-1.2A / dm 2 , air stirring.

[0027] Preferably, the thickness of the cyanide-free cadmium iron alloy coating is 6 to 22 μm, and is prepared by the potassium chloride cadmium iron alloy plating process of the present invention: Cadmium chloride 25-35 g / L, ferrous chloride tetrahydrate 4-6 g / L, potassium chloride 100-140 g / L, complexing agent 100-140 g / L, leveling agent 1.5-2.5 mL / L, brightener 1.5-2.5 mL / L, auxiliary agent 25-30 mL / L, stabilizer 25-35 g / L, plating solution pH 6-8, plating tank temperature 20-35 ° C, cathode current density 0.5-1.5 A / dm 2 The cathode moves 2 to 4 m / min, the anode is made of a cadmium plate with a mass fraction of 99.97%, and the area ratio of the cathode to the anode is 2:(0.7 to 1.3); during production, a 30% mass fraction of ferrous chloride tetrahydrate solution is added to the plating tank to keep its mass concentration within the process range.

[0028] Preferably, the leveling agent includes 5-10 g / L of trimercapto-s-triazine, 30-60 g / L of an organic amine epoxy derivative with the model number GDX sold by Safek New Materials Co., Ltd., and 5-10 g / L of sodium hydroxide.

[0029] Preferably, the stabilizer includes sodium glucoheptanoate and sodium hydrogen succinate, and the mass ratio of sodium glucoheptanoate to sodium hydrogen succinate is 1:(2-3).

[0030] Preferably, the complexing agent includes nitrilotriacetic acid, sulfosalicylic acid, and malic acid, and the mass ratio of nitrilotriacetic acid, sulfosalicylic acid, and malic acid is 3:(1-2):(4-6). The above components are mixed evenly to obtain the complexing agent.

[0031] Preferably, the brightener comprises three components A, B, and C, wherein component A comprises α-vinyl-N-propanesulfonic acid pyridine inner salt, component B comprises any one or two of 3-methoxy-4-hydroxybenzaldehyde, 3,4-dimethoxybenzaldehyde, and 4-methoxybenzaldehyde, and component C comprises any one or two of propargyl alcohol ethoxy ether, propargyl alcohol propoxy ether, N,N-diethylpropargylamine, N,N-diethylpropargylamine formate, and N,N-diethylpropargylamine sulfate; 30 kg of isopropanol is added to 40 kg of water and mixed evenly, 3 to 8 kg of component A, 3 to 5 kg of component B, and 6 to 10 kg of component C are added, stirred to dissolve, and water is added to 100 L to obtain the brightener.

[0032] Preferably, the auxiliary agent includes polyacrylamide with a molecular weight less than 8000, sodium salt of 2-ethylhexyl sulfate, a condensate composed of ethylenediamine or dimethylpropylamine and epichlorohydrin, and component D, and component D is consistent with component C in the brightener; 5-8 kg of polyacrylamide with a molecular weight less than 8000, 2-5 kg ​​of condensate of ethylenediamine or dimethylpropylamine and epichlorohydrin, 3-8 kg of sodium salt of 2-ethylhexyl sulfate, and 3-6 kg of component D are added to 70 kg of water, stirred to dissolve, and water is added to 100 L to obtain the auxiliary agent.

[0033] After the high-strength structural steel workpiece is plated with cadmium iron alloy, a dehydrogenation treatment is performed. Preferably, the plated workpiece is dehydrogenated at 200° C. for 8 to 24 hours.

[0034] After dehydrogenation, the high-strength structural steel workpiece is subjected to the current hexavalent passivation process to prepare the passivation film.

[0035] Preferably, the chromium passivation film is prepared using HC-5 high protection color passivation agent from Chaobang Chemical: The volume concentration of HC-5 high protection color passivator is 2% to 4%, the passivation temperature is 20 to 35°C, the pH value of the passivation solution is 1.3 to 2.0, the passivation time is 5 to 20s, and weak air stirring or workpiece swing is used.

[0036] Preferably, the passivation film is prepared using Chaobang Chemical's OVG-31 military green passivation process: OVG-31 military green passivation agent 80-120mL / L, passivation solution pH 1.0-1.6, passivation temperature 20-30℃, passivation time 30-90s, air stirring or swinging the plated parts; Preferably, the passivation film is prepared using Chaobang Chemical's BZ-71 cadmium black passivation process: BZ-71A cadmium black passivation agent 80~100mL / L, BZ-71B cadmium black passivation agent 80~100mL / L, passivation solution pH value 1.1~1.5, passivation temperature 20~35℃, passivation time 15~40s, air stirring or swinging the plated parts.

[0037] Preferably, the passivation film is prepared using the UC-91 cadmium olive-drab passivation process of Chaobang Chemical: Chromic anhydride 25-45g / L, phosphoric acid 8-16ml / L, UC-91 activator 4-8ml / L, UC-91 colorant 1-2g / L, passivation temperature 20-28℃, passivation time 30-60s, stir or swing the workpiece with weak air.

[0038] Preferably, the specific process of the passivation process is "lighting with nitric acid with a volume fraction of 1.5% → water washing → passivation → water washing → out of the tank → using high-pressure air to blow away the water droplets remaining on the surface of the plated part".

[0039] After passivation, high-strength structural steel workpieces should be dried at 55-60°C for 10-15 minutes.

[0040] Example 1: like Figure 1 As shown, a cyanide-free cadmium-iron alloy plating process for high-strength structural steel includes pre-treatment of a high-strength structural steel substrate 1, and sequentially preparing a nickel-titanium alloy coating 2, a cyanide-free cadmium-iron alloy coating 3, and a hexavalent chromium colored passivation film 4 on the high-strength structural steel substrate 1 from the inside to the outside.

[0041] 1. Pre-treatment: The high-strength structural steel workpiece substrate 1 is subjected to "alkaline chemical degreasing → water washing → alkaline anodic electrolytic degreasing → water washing → sulfuric acid anodic electrolytic activation → water washing".

[0042] The sulfuric acid anode electrolytic activation adopts the following anode electrolytic activation process: Sulfuric acid 150g / L, operating at room temperature, with the workpiece to be plated as the anode and the titanium plate as the cathode, the anode current density is 1.5A / dm 2 , electrolysis for 30s.

[0043] 2. Nickel-titanium alloy plating: After pre-treatment of the high-strength structural steel workpiece, a nickel-titanium alloy coating 2 was prepared using the NT-770 nickel-titanium alloy plating process of Chaobang Chemical, and the coating thickness was 6 μm.

[0044] Nickel sulfate hexahydrate 58g / L, nickel chloride hexahydrate 12g / L, titanyl sulfate 12g / L, boric acid 35g / L, trisodium citrate 58g / L, succinimidyl 10g / L, NT-770 brightener 3mL / L, NT-770 auxiliary agent 10mL / L, plating solution pH 4.5, plating tank temperature 53℃, cathode current density 0.8A / dm 2 , air stirring.

[0045] 3. Cadmium-plated iron alloy: After high-strength structural steel workpieces were plated with nickel-titanium alloy, a cyanide-free cadmium iron alloy coating 3 was prepared using the potassium chloride cadmium iron alloy plating process developed by Chaobang Chemical. The coating thickness was 12 μm.

[0046] Cadmium chloride 30g / L, ferrous chloride tetrahydrate 5g / L, potassium chloride 120g / L, complexing agent 120g / L, leveling agent 2mL / L, brightener 2mL / L, auxiliary agent 27mL / L, stabilizer 30g / L, plating solution pH 7, plating tank temperature 30℃, cathode current density 1A / dm 2 The cathode moves 3m / min, the anode is made of cadmium plate with a mass fraction of 99.97%, the area ratio of cathode to anode is 2:1, and during production, 30% mass fraction of ferrous chloride tetrahydrate solution is added to the plating tank to keep its mass concentration within the process range.

[0047] The leveling agent includes 7.5 g / L of trimercapto-s-triazine, 45 g / L of an organic amine epoxy derivative with the model number GDX sold by Safek New Materials Co., Ltd., and 7.5 g / L of sodium hydroxide.

[0048] The stabilizer includes sodium glucose heptanate and sodium hydrogen succinate, and the mass ratio of sodium glucose heptanate to sodium hydrogen succinate is 1:2.5.

[0049] The complexing agent includes nitrilotriacetic acid, sulfosalicylic acid, and malic acid, and the above components are mixed evenly to obtain the complexing agent; the mass ratio of nitrilotriacetic acid, sulfosalicylic acid, and malic acid is 3:1.5:5.

[0050] The brightener comprises three components, A, B, and C; component A comprises α-vinyl-N-propanesulfonic acid pyridine inner salt; component B comprises any one or two of 3-methoxy-4-hydroxybenzaldehyde, 3,4-dimethoxybenzaldehyde, and 4-methoxybenzaldehyde; and component C comprises any one or two of propargyl alcohol ethoxy ether, propargyl alcohol propoxy ether, N,N-diethylpropargylamine, N,N-diethylpropargylamine formate, and N,N-diethylpropargylamine sulfate. 30 kg of isopropyl alcohol is added to 40 kg of water and mixed evenly; 5.5 kg of component A, 5.5 kg of component B, and 8 kg of component C are added, stirred to dissolve, and water is added to 100 L to obtain the brightener.

[0051] The auxiliary agent includes polyacrylamide with a molecular weight of less than 8000, sodium salt of 2-ethylhexyl sulfate, a condensate of ethylenediamine or dimethylpropylamine and epichlorohydrin, and component D, and component D is consistent with component C in the brightener; 5.5 kg of polyacrylamide with a molecular weight of less than 8000, 3.5 kg of condensate of ethylenediamine or dimethylpropylamine and epichlorohydrin, 5.5 kg of sodium salt of 2-ethylhexyl sulfate, and 4.5 kg of component D are added to 70 kg of water, stirred to dissolve, and water is added to 100 L to obtain the auxiliary agent.

[0052] 4. Hydrogen removal: After high-strength structural steel workpieces are plated with cadmium iron, the plated parts are dehydrogenated at 200°C for 24 hours.

[0053] 5. Passivation: After dehydrogenation, the high-strength structural steel workpiece was treated with HC-5 high-protection color passivator produced by Chaobang Chemical to prepare a hexavalent chromium color passivation film 4.

[0054] The volume concentration of HC-5 high protection color passivator is 3%, the passivation temperature is 30℃, the pH of the passivation solution is 1.8, the passivation time is 10s, and the workpiece is swung.

[0055] The specific process is "1.5% volume fraction nitric acid polishing → water washing → passivation → water washing → out of the tank → use high-pressure air to blow away the remaining water droplets on the surface of the plated part".

[0056] 6. Drying: After passivation, high-strength structural steel workpieces were dried at 56°C for 15 minutes.

[0057] Example 2: like Figure 1 As shown, a cyanide-free cadmium-iron alloy plating process for high-strength structural steel includes pre-treatment of a high-strength structural steel substrate 1, and sequentially preparing a nickel-titanium alloy coating 2, a cyanide-free cadmium-iron alloy coating 3, and a hexavalent chromium military green passivation film 4 on the high-strength structural steel substrate 1 from the inside to the outside.

[0058] 1. Pre-treatment: The high-strength structural steel workpiece substrate 1 is subjected to "alkaline chemical degreasing → water washing → alkaline anodic electrolytic degreasing → water washing → sulfuric acid anodic electrolytic activation → water washing".

[0059] The sulfuric acid anode electrolytic activation adopts the following anode electrolytic activation process: Sulfuric acid 200g / L, operating at room temperature, with the workpiece to be plated as the anode and the titanium plate as the cathode, the anode current density is 1.5A / dm 2 , electrolysis for 30s.

[0060] 2. Nickel-titanium alloy plating: After pre-treatment of the high-strength structural steel workpiece, a nickel-titanium alloy coating 2 was prepared using the NT-770 nickel-titanium alloy plating process of Chaobang Chemical, and the coating thickness was 6 μm.

[0061] Nickel sulfate hexahydrate 55g / L, nickel chloride hexahydrate 10g / L, titanyl sulfate 10g / L, boric acid 35g / L, trisodium citrate 55g / L, succinimidyl 10g / L, NT-770 brightener 3mL / L, NT-770 auxiliary agent 10mL / L, plating solution pH 4.2, plating tank temperature 55℃, cathode current density 0.8A / dm 2 , air stirring.

[0062] 3. Cadmium-plated iron alloy: After high-strength structural steel workpieces were plated with nickel-titanium alloy, a cyanide-free cadmium iron alloy coating 3 was prepared using the potassium chloride cadmium iron alloy plating process developed by Chaobang Chemical. The coating thickness was 12 μm.

[0063] Cadmium chloride 35g / L, ferrous chloride tetrahydrate 6g / L, potassium chloride 100g / L, complexing agent 140g / L, leveling agent 2mL / L, brightener 2mL / L, auxiliary agent 27mL / L, stabilizer 35g / L, plating solution pH 6.5, plating tank temperature 20℃, cathode current density 1A / dm 2 The cathode moves 3m / min, the anode is made of cadmium plate with a mass fraction of 99.97%, the area ratio of cathode to anode is 2:1, and during production, 30% mass fraction of ferrous chloride tetrahydrate solution is added to the plating tank to keep its mass concentration within the process range.

[0064] The leveling agent includes 7.5 g / L of trimercapto-s-triazine, 45 g / L of an organic amine epoxy derivative with the model number GDX sold by Safek New Materials Co., Ltd., and 7.5 g / L of sodium hydroxide.

[0065] The stabilizer includes sodium glucose heptanate and sodium hydrogen succinate, and the mass ratio of sodium glucose heptanate to sodium hydrogen succinate is 1:2.5.

[0066] The complexing agent includes nitrilotriacetic acid, sulfosalicylic acid, and malic acid, and the above components are mixed evenly to obtain the complexing agent; the mass ratio of nitrilotriacetic acid, sulfosalicylic acid, and malic acid is 3:1.5:5.

[0067] The brightener comprises three components, A, B, and C; component A comprises α-vinyl-N-propanesulfonic acid pyridine inner salt; component B comprises any one or two of 3-methoxy-4-hydroxybenzaldehyde, 3,4-dimethoxybenzaldehyde, and 4-methoxybenzaldehyde; and component C comprises any one or two of propargyl alcohol ethoxy ether, propargyl alcohol propoxy ether, N,N-diethylpropargylamine, N,N-diethylpropargylamine formate, and N,N-diethylpropargylamine sulfate. 30 kg of isopropyl alcohol is added to 40 kg of water and mixed evenly; 5.5 kg of component A, 5.5 kg of component B, and 8 kg of component C are added, stirred to dissolve, and water is added to 100 L to obtain the brightener.

[0068] The auxiliary agent includes polyacrylamide with a molecular weight of less than 8000, sodium salt of 2-ethylhexyl sulfate, a condensate of ethylenediamine or dimethylpropylamine and epichlorohydrin, and component D, and component D is consistent with component C in the brightener; 5.5 kg of polyacrylamide with a molecular weight of less than 8000, 3.5 kg of condensate of ethylenediamine or dimethylpropylamine and epichlorohydrin, 5.5 kg of sodium salt of 2-ethylhexyl sulfate, and 4.5 kg of component D are added to 70 kg of water, stirred to dissolve, and water is added to 100 L to obtain the auxiliary agent.

[0069] 4. Hydrogen removal: After cadmium plating, high-strength structural steel workpieces are dehydrogenated at 200℃ for 24 hours.

[0070] 5. Passivation: After dehydrogenation, the high-strength structural steel workpiece is subjected to the military green passivation process of Chaobang Chemical's OVG-31 produced by Chaobang Chemical to prepare the military green passivation film 5.

[0071] OVG-31 military green passivation agent 100mL / L, passivation solution pH 1.3, passivation temperature 25℃, passivation time 60s, swing plated parts.

[0072] The specific process is "1.5% volume fraction nitric acid polishing → water washing → passivation → water washing → out of the tank → use high-pressure air to blow away the remaining water droplets on the surface of the plated part".

[0073] 6. Drying: After passivation, high-strength structural steel workpieces are dried at 60°C for 10 minutes.

[0074] Example 3: like Figure 1 As shown, a cyanide-free cadmium-iron alloy plating process for high-strength structural steel includes pretreatment of a high-strength structural steel substrate 1, and sequentially preparing a nickel-titanium alloy coating 2, a cyanide-free cadmium-iron alloy coating 3, and a hexavalent chromium black passivation film 4 on the high-strength structural steel substrate 1 from the inside to the outside.

[0075] 1. Pre-treatment: The high-strength structural steel workpiece substrate 1 is subjected to "alkaline chemical degreasing → water washing → alkaline anodic electrolytic degreasing → water washing → sulfuric acid anodic electrolytic activation → water washing".

[0076] The sulfuric acid anode electrolytic activation adopts the following anode electrolytic activation process: Sulfuric acid 100g / L, operating at room temperature, with the workpiece to be plated as the anode and the titanium plate as the cathode, the anode current density is 1.5A / dm 2 , electrolysis 50s.

[0077] 2. Nickel-titanium alloy plating: After pre-treatment of the high-strength structural steel workpiece, a nickel-titanium alloy coating 2 was prepared using the NT-770 nickel-titanium alloy plating process of Chaobang Chemical, and the coating thickness was 6 μm.

[0078] Nickel sulfate hexahydrate 53g / L, nickel chloride hexahydrate 8g / L, titanyl sulfate 8g / L, boric acid 38g / L, trisodium citrate 53g / L, succinimidyl 10g / L, NT-770 brightener 3mL / L, NT-770 auxiliary agent 10mL / L, plating solution pH 4, plating tank temperature 58℃, cathode current density 1A / dm 2 , air stirring.

[0079] 3. Cadmium-plated iron alloy: After high-strength structural steel workpieces were plated with nickel-titanium alloy, a cyanide-free cadmium iron alloy coating 3 was prepared using the potassium chloride cadmium iron alloy plating process developed by Chaobang Chemical. The coating thickness was 12 μm.

[0080] Cadmium chloride 25g / L, ferrous chloride tetrahydrate 4g / L, potassium chloride 140g / L, complexing agent 100g / L, leveling agent 2mL / L, brightener 2mL / L, auxiliary agent 27mL / L, stabilizer 25g / L, plating solution pH 67.5, plating tank temperature 35℃, cathode current density 1A / dm 2 The cathode moves 3m / min, the anode is made of cadmium plate with a mass fraction of 99.97%, the area ratio of cathode to anode is 2:1, and during production, 30% mass fraction of ferrous chloride tetrahydrate solution is added to the plating tank to keep its mass concentration within the process range.

[0081] The leveling agent includes 7.5 g / L of trimercapto-s-triazine, 45 g / L of an organic amine epoxy derivative with the model number GDX sold by Safek New Materials Co., Ltd., and 7.5 g / L of sodium hydroxide.

[0082] The stabilizer includes sodium glucose heptanate and sodium hydrogen succinate, and the mass ratio of sodium glucose heptanate to sodium hydrogen succinate is 1:2.5.

[0083] The complexing agent includes nitrilotriacetic acid, sulfosalicylic acid, and malic acid, and the above components are mixed evenly to obtain the complexing agent; the mass ratio of nitrilotriacetic acid, sulfosalicylic acid, and malic acid is 3:1.5:5.

[0084] The brightener comprises three components, A, B, and C; component A comprises α-vinyl-N-propanesulfonic acid pyridine inner salt; component B comprises any one or two of 3-methoxy-4-hydroxybenzaldehyde, 3,4-dimethoxybenzaldehyde, and 4-methoxybenzaldehyde; and component C comprises any one or two of propargyl alcohol ethoxy ether, propargyl alcohol propoxy ether, N,N-diethylpropargylamine, N,N-diethylpropargylamine formate, and N,N-diethylpropargylamine sulfate. 30 kg of isopropyl alcohol is added to 40 kg of water and mixed evenly; 5.5 kg of component A, 5.5 kg of component B, and 8 kg of component C are added, stirred to dissolve, and water is added to 100 L to obtain the brightener.

[0085] The auxiliary agent includes polyacrylamide with a molecular weight of less than 8000, sodium salt of 2-ethylhexyl sulfate, a condensate of ethylenediamine or dimethylpropylamine and epichlorohydrin, and component D, and component D is consistent with component C in the brightener; 5.5 kg of polyacrylamide with a molecular weight of less than 8000, 3.5 kg of condensate of ethylenediamine or dimethylpropylamine and epichlorohydrin, 5.5 kg of sodium salt of 2-ethylhexyl sulfate, and 4.5 kg of component D are added to 70 kg of water, stirred to dissolve, and water is added to 100 L to obtain the auxiliary agent.

[0086] 4. Hydrogen removal: After cadmium plating, high-strength structural steel workpieces are dehydrogenated at 200℃ for 24 hours.

[0087] 5. Passivation: After dehydrogenation, the high-strength structural steel workpiece was treated with Chaobang Chemical's BZ-71 cadmium black passivation process to prepare a hexavalent chromium black passivation film 4.

[0088] BZ-71A cadmium black passivation agent 90mL / L, BZ-71B cadmium black passivation agent 90mL / L, passivation solution pH 1.3, passivation temperature 25℃, passivation time 28s, swing plated parts.

[0089] The specific process is "1.5% volume fraction nitric acid polishing → water washing → passivation → water washing → out of the tank → use high-pressure air to blow away the remaining water droplets on the surface of the plated part".

[0090] 7. Drying: After passivation, high-strength structural steel workpieces were dried at 58°C for 10 minutes.

[0091] Example 4: like Figure 1As shown, a cyanide-free cadmium-iron alloy plating process for high-strength structural steel includes pre-treatment of a high-strength structural steel substrate 1, and sequentially preparing a nickel-titanium alloy coating 2, a cyanide-free cadmium-iron alloy coating 3, and a hexavalent chromium olive-drab passivation film 4 on the high-strength structural steel substrate 1 from the inside to the outside.

[0092] 1. Pre-treatment: The high-strength structural steel workpiece substrate 1 is subjected to "alkaline chemical degreasing → water washing → alkaline anodic electrolytic degreasing → water washing → sulfuric acid anodic electrolytic activation → water washing".

[0093] The sulfuric acid anode electrolytic activation adopts the following anode electrolytic activation process: Sulfuric acid 150g / L, operating at room temperature, with the workpiece to be plated as the anode and the titanium plate as the cathode, the anode current density is 2A / dm 2 , electrolysis for 20s.

[0094] 2. Nickel-titanium alloy plating: After pre-treatment of the high-strength structural steel workpiece, a nickel-titanium alloy coating 2 was prepared using the NT-770 nickel-titanium alloy plating process of Chaobang Chemical, and the coating thickness was 6 μm.

[0095] Nickel sulfate hexahydrate 50g / L, nickel chloride hexahydrate 5g / L, titanyl sulfate 5g / L, boric acid 30g / L, trisodium citrate 50g / L, succinimidyl 10g / L, NT-770 brightener 3mL / L, NT-770 auxiliary agent 10mL / L, plating solution pH 3.5, plating tank temperature 60℃, cathode current density 1A / dm 2 , air stirring.

[0096] 3. Cadmium-plated iron alloy: After high-strength structural steel workpieces were plated with nickel-titanium alloy, a cyanide-free cadmium iron alloy coating 3 was prepared using the potassium chloride cadmium iron alloy plating process developed by Chaobang Chemical. The coating thickness was 12 μm.

[0097] Cadmium chloride 28g / L, ferrous chloride tetrahydrate 4.5g / L, potassium chloride 130g / L, complexing agent 115g / L, leveling agent 2mL / L, brightener 2mL / L, auxiliary agent 28mL / L, stabilizer 28g / L, plating solution pH 8, plating tank temperature 30℃, cathode current density 1A / dm 2 The cathode moves 3m / min, the anode is made of cadmium plate with a mass fraction of 99.97%, the area ratio of cathode to anode is 2:1, and during production, 30% mass fraction of ferrous chloride tetrahydrate solution is added to the plating tank to keep its mass concentration within the process range.

[0098] The leveling agent includes 7.5 g / L of trimercapto-s-triazine, 45 g / L of an organic amine epoxy derivative with the model number GDX sold by Safek New Materials Co., Ltd., and 7.5 g / L of sodium hydroxide.

[0099] The stabilizer includes sodium glucose heptanate and sodium hydrogen succinate, and the mass ratio of sodium glucose heptanate to sodium hydrogen succinate is 1:2.5.

[0100] The complexing agent includes nitrilotriacetic acid, sulfosalicylic acid, and malic acid, and the above components are mixed evenly to obtain the complexing agent; the mass ratio of nitrilotriacetic acid, sulfosalicylic acid, and malic acid is 3:1.5:5.

[0101] The brightener comprises three components, A, B, and C; component A comprises α-vinyl-N-propanesulfonic acid pyridine inner salt; component B comprises any one or two of 3-methoxy-4-hydroxybenzaldehyde, 3,4-dimethoxybenzaldehyde, and 4-methoxybenzaldehyde; and component C comprises any one or two of propargyl alcohol ethoxy ether, propargyl alcohol propoxy ether, N,N-diethylpropargylamine, N,N-diethylpropargylamine formate, and N,N-diethylpropargylamine sulfate. 30 kg of isopropyl alcohol is added to 40 kg of water and mixed evenly; 5.5 kg of component A, 5.5 kg of component B, and 8 kg of component C are added, stirred to dissolve, and water is added to 100 L to obtain the brightener.

[0102] The auxiliary agent includes polyacrylamide with a molecular weight of less than 8000, sodium salt of 2-ethylhexyl sulfate, a condensate of ethylenediamine or dimethylpropylamine and epichlorohydrin, and component D, and component D is consistent with component C in the brightener; 5.5 kg of polyacrylamide with a molecular weight of less than 8000, 3.5 kg of condensate of ethylenediamine or dimethylpropylamine and epichlorohydrin, 5.5 kg of sodium salt of 2-ethylhexyl sulfate, and 4.5 kg of component D are added to 70 kg of water, stirred to dissolve, and water is added to 100 L to obtain the auxiliary agent.

[0103] 4. Hydrogen removal: After cadmium plating, high-strength structural steel workpieces are dehydrogenated at 200℃ for 24 hours.

[0104] 5. Passivation: After dehydrogenation, the high-strength structural steel workpiece was treated with Chaobang Chemical's UC-91 cadmium hexavalent chromium olive passivation process to prepare a hexavalent chromium olive passivation film 4.

[0105] Chromic anhydride 30g / L, phosphoric acid 12ml / L, UC-91 activator 6ml / L, UC-91 colorant 1.5g / L, passivation temperature 25℃, passivation time 45s, swing the workpiece.

[0106] The specific process is "1.5% volume fraction nitric acid polishing → water washing → passivation → water washing → out of the tank → use high-pressure air to blow away the remaining water droplets on the surface of the plated part".

[0107] 6. Drying: After passivation, high-strength structural steel workpieces are dried at 55°C for 15 minutes.

[0108] Test Example 1: The high-strength structural steel is 23Co14Ni12Cr3Mo. A hydrogen embrittlement test bar was prepared in accordance with HB 5067.1–2005 "Hydrogen Embrittlement Test for Coating Processes Part 1: Mechanical Method." A nickel-titanium alloy coating and a potassium chloride-cyanide-free cadmium iron alloy coating were sequentially prepared on the degreased surface of the test bar according to the process requirements of Example 1. The test bar was then dehydrogenated at 200°C for 24 hours. According to the HB5067.1–2005 standard, the test bar was stretched for 200 hours without breaking, and the test results met the standard requirements.

[0109] Test Example 2: Acetate salt spray tests were conducted in accordance with GB / T 10125–2021, "Artificial Atmosphere Corrosion Test - Salt Spray Test." The cadmium-iron alloy hexavalent chromium color passivation sample prepared in Example 1 showed no white rust on its surface after 400 hours. The cadmium-iron alloy hexavalent chromium military green passivation sample prepared in Example 2 showed no white rust on its surface after 420 hours. The cadmium-iron alloy hexavalent chromium black passivation sample prepared in Example 3 showed no white rust on its surface after 368 hours. The cadmium-iron alloy hexavalent chromium olive drab passivation sample prepared in Example 4 showed no white rust on its surface after 400 hours. These tests demonstrate that the cadmium-iron alloy coatings prepared in the present invention have excellent corrosion resistance.

[0110] Test Example 3: The high-strength structural steel cadmium-plated iron alloy samples prepared in Example 1, Example 2, Example 3, and Example 4 were tested for coating adhesion using a thermal shock test method in accordance with GB / T 5270-2005 "Review of test methods for adhesion strength of electrodeposited and chemically deposited metallic coatings on metal substrates." The samples were heated to 300° C. in a heating furnace for 30 minutes, then removed and quenched in room temperature water. No blistering or shedding of the coating occurred, indicating good coating adhesion.

[0111] Test Example 4: The high-strength steel cadmium-plated iron alloy samples prepared in Example 1, Example 2, Example 3, and Example 4 were subjected to a mold test for 28 days in accordance with GJB 150.9A-2009 "Military Equipment Laboratory Environmental Test Method Part 10: Mold Test". No mold grew on the surface of the samples, which met the industry standard requirements.

[0112] The technical solutions provided by the embodiments of the present invention are described in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the embodiments of the present invention. The description of the above embodiments is only intended to help understand the principles of the embodiments of the present invention. It should be noted that for those skilled in the art, based on the principles and concepts of the embodiments of the present invention, there may be changes in the specific implementation methods and scope of application, but all of these should fall within the scope of protection of the present invention.

Claims

1. A cyanide-free cadmium iron alloy plating process for high-strength structural steel, characterized in that: Including the following process: (1) Pretreatment of high-strength structural steel, including sandblasting, degreasing, and sulfuric acid anode activation; (2) After pretreatment of high-strength structural steel, a nickel-titanium alloy coating is prepared by a nickel-titanium alloy plating process; (3) After high-strength structural steel is plated with nickel-titanium alloy, a cyanide-free cadmium iron alloy coating is prepared using a potassium chloride cadmium iron alloy plating process; (4) High-strength structural steel is subjected to dehydrogenation treatment after potassium chloride, cadmium and iron alloying; (5) After dehydrogenation of high-strength structural steel, a passivation film is prepared using the current passivation process; The potassium chloride cadmium iron alloy plating process includes the following components and process parameters: Cadmium chloride 25-35g / L, ferrous chloride tetrahydrate 4-6g / L, potassium chloride 100-140g / L, complexing agent 100-140g / L, leveling agent 1.5-2.5mL / L, brightener 1.5-2.5mL / L, auxiliary agent 25-30mL / L, stabilizer 25-35g / L, plating solution pH 6-8, plating tank temperature 20-35℃, cathode current density 0.5-1.5A / dm 2 , cathode moves 2-4 m / min; The leveling agent includes 5-10 g / L of trimercapto-s-triazine, 30-60 g / L of organic amine epoxy derivative with model number GDX, and 5-10 g / L of sodium hydroxide; The stabilizer comprises sodium glucoheptanoate and sodium hydrogen succinate, and the mass ratio of sodium glucoheptanoate to sodium hydrogen succinate is 1:(2-3); The complexing agent includes nitrilotriacetic acid, sulfosalicylic acid, and malic acid, wherein the mass ratio of nitrilotriacetic acid, sulfosalicylic acid, and malic acid is 3:(1-2):(4-6), and the above components are mixed uniformly to obtain the complexing agent; The brightener comprises three components, A, B and C, wherein the component A comprises α-vinyl-N-propanesulfonic acid pyridine inner salt, the component B comprises any one or two of 3-methoxy-4-hydroxybenzaldehyde, 3,4-dimethoxybenzaldehyde and 4-methoxybenzaldehyde, and the component C comprises any one or two of propargyl alcohol ethoxy ether, propargyl alcohol propoxy ether, N,N-diethylpropargylamine, N,N-diethylpropargylamine formate and N,N-diethylpropargylamine sulfate; 30 kg of isopropanol is added to 40 kg of water and mixed evenly, 3-8 kg of the component A, 3-5 kg ​​of the component B and 6-10 kg of the component C are added, stirred to dissolve, and water is added to 100 L to obtain the brightener; The auxiliary agent comprises polyacrylamide with a molecular weight less than 8000, sodium salt of 2-ethylhexyl sulfate, a condensate of ethylenediamine or dimethylpropylamine and epichlorohydrin, and a D component, wherein the D component is consistent with the C component in the brightener; 5-8 kg of polyacrylamide with a molecular weight less than 8000, 2-5 kg ​​of a condensate of ethylenediamine or dimethylpropylamine and epichlorohydrin, 3-8 kg of sodium salt of 2-ethylhexyl sulfate, and 3-6 kg of the D component are added to 70 kg of water, stirred to dissolve, and water is added to 100 L to obtain the auxiliary agent.

2. The cyanide-free cadmium iron alloy electroplating process according to claim 1, characterized in that: The anode is made of cadmium plate with a mass fraction of 99.97%.

3. The cyanide-free cadmium iron alloy electroplating process according to claim 1, characterized in that: The area ratio of the cathode to the anode is 2:(0.7-1.3).

4. The cyanide-free cadmium iron alloy electroplating process according to claim 1, 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 4-6 g / L.

5. The cyanide-free cadmium iron alloy electroplating process according to claim 1, characterized in that: The nickel-titanium alloy plating process adopts the NT-770 nickel-titanium alloy plating process, including the following components and process parameters: Nickel sulfate hexahydrate 50-60g / L, nickel chloride hexahydrate 5-15g / L, titanyl sulfate 5-15g / L, boric acid 30-40g / L, trisodium citrate 50-60g / L, succinimidyl 8-12g / L, NT-770 brightener 2-4mL / L, NT-770 auxiliary agent 8-12mL / L, plating solution pH 3.5-5.0, plating tank temperature 50-60℃, cathode current density 0.6-1.2A / dm 2 , air stirring.

6. The cyanide-free cadmium iron alloy plating process for high-strength structural steel according to claim 1, characterized in that: The high-strength structural steel matrix pretreatment includes: sandblasting, alkaline chemical degreasing, alkaline anodic electrolytic degreasing, and sulfuric acid anodic electrolytic activation.

7. The cyanide-free cadmium iron alloy plating process for high-strength structural steel according to claim 1 or 6, characterized in that: The sulfuric acid anode electrolytic activation includes the following components and process parameters: Sulfuric acid 100-200g / L, operating at room temperature, with the workpiece to be plated as the anode and the titanium plate as the cathode, the anode current density is 1-2A / dm 2 , electrolysis for 20 to 60 seconds.

8. The cyanide-free cadmium iron alloy plating process for high-strength structural steel according to claim 1, characterized in that: The thickness of the nickel-titanium alloy coating is 4-8 μm.

9. The cyanide-free cadmium iron alloy plating process for high-strength structural steel as claimed in claim 1, characterized in that: The thickness of the cyanide-free cadmium iron alloy coating is 6 to 22 μm.

10. The cyanide-free cadmium iron alloy plating process for high-strength structural steel according to claim 1, characterized in that: The passivation film is prepared by a hexavalent chromium passivation process.

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