Cyanide-free cadmium-iron alloy plating solution and electroplating process

Abstract

The plating solution comprises the following components and process parameters: 25-35 g / L of cadmium chloride, 4-6 g / L of ferrous chloride tetrahydrate, 100-140 g / L of potassium chloride, 100-140 g / L of a coordination agent, 1.5-2.5 mL / L of a leveling agent, 1.5-2.5 mL / L of a brightening agent, 25-30 mL / L of an auxiliary agent and 25-35 g / L of a stabilizer, the pH value of the plating solution is 6-8, the temperature of a plating tank is 20-35 DEG C, the cathode current density is 0.5-1.5 A / dm < 2 >, and the cathode movement is 2-4 m / min. According to the prepared cadmium-plated iron alloy sample piece subjected to color passivation through hexavalent chromium, the surface of the sample piece is free of white rust in an acetate mist test for 520 h according to GB / T 10125-2021 Artificial Atmosphere Corrosion Test Salt Spray Test, and a plating layer has excellent corrosion resistance.

Description

Technical Field

[0001] The invention relates to the field of electroplating, in particular to a cyanide-free cadmium-iron alloy plating solution and an electroplating process. Background Art

[0002] In addition to the cyanide-free cadmium plating process, there are also cyanide-free cadmium plating titanium alloy, cyanide-free cadmium plating tin alloy, cyanide-free cadmium plating cobalt alloy and other cadmium alloy plating processes in production applications. The performance of cadmium alloy plating is usually better than that of single-component cadmium plating, and can meet the special requirements of some aerospace parts.

[0003] Iron is a very cost-effective metal that can form alloys with common metals with excellent properties. In the field of electroplating, cyanide-free zinc-iron alloy plating has been widely used, but there is no literature report on cyanide-free cadmium-iron alloy plating. Summary of the invention

[0004] In order to fill the market gap of cyanide-free cadmium iron alloy plating, the present invention provides a cyanide-free cadmium iron alloy plating solution and electroplating process. In order to achieve the above purpose, the present invention adopts the following technical solutions: A cyanide-free cadmium-iron alloy plating solution comprises the following components and contents: 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; The leveling agent includes 5-10 g / L of trimercapto-s-triazine, 30-60 g / L of organic amine epoxy derivative, and 5-10 g / L of sodium hydroxide; The stabilizer includes sodium gluconate and sodium hydrogen succinate, and the mass ratio of sodium gluconate to sodium hydrogen succinate is 1:(2-3); The ligand comprises nitrilotriacetic acid, sulfosalicylic acid and malic acid. The ligand is obtained by uniformly mixing the above components. The mass ratio of nitrilotriacetic acid, sulfosalicylic acid and malic acid is 3:(1-2):(4-6).

[0005] In some embodiments, the brightener includes three components A, B, and C, component A includes α-vinyl-N-propanesulfonic acid pyridine inner salt, component B includes any one or two of 3-methoxy-4-hydroxybenzaldehyde, 3,4-dimethoxybenzaldehyde, and 4-methoxybenzaldehyde, and component C includes 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.

[0006] In some embodiments, 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, 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.

[0007] In some embodiments, the cyanide-free cadmium iron alloy plating solution is prepared as follows: a) Add 4 / 5 of water into the plating tank according to the volume of the plating solution, add sodium hydroxide, potassium chloride and complexing agent according to the process requirements, the mass ratio of sodium hydroxide to complexing agent is 1:2, and stir to dissolve the above substances; b) adding cadmium chloride and ferrous chloride tetrahydrate according to the process requirements, and stirring until the solid matter is dissolved; c) Add leveling agent, brightener, auxiliary agent, and stabilizer according to the process requirements, stir until the stabilizer is completely dissolved, adjust the pH of the plating solution to between 6 and 8 with a 10% sodium hydroxide solution, add water to the specified volume, and keep the temperature at 0.05 to 0.1A / dm 2 Electrolyze for 1 to 8 hours at this current density.

[0008] A cyanide-free cadmium iron alloy electroplating 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, the cathode moves 2 to 4 m / min.

[0009] In some of the embodiments, the anode is made of a cadmium plate having a mass fraction of 99.97%.

[0010] In some embodiments, the area ratio of the cathode to the anode is 2:(0.7-1.3).

[0011] In some of the embodiments, a filter is used to circulate and filter the plating solution during production.

[0012] 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.

[0013] In some embodiments, the cyanide-free cadmium iron alloy electroplating process includes the following process: a) preparing cyanide-free cadmium iron alloy plating solution; b) Pre-treat the workpiece using the current pre-treatment method; c) Cadmium iron alloy plating after workpiece pre-treatment; d) After the workpiece is plated with cadmium iron alloy, it is passivated using the current passivation process.

[0014] The beneficial effects of the present invention are: 1. The cyanide-free cadmium iron alloy plating solution and electroplating process disclosed in the present invention have a salt spray resistance of the cyanide-free cadmium iron alloy coating prepared therefrom which is higher than that of the cyanide-free cadmium plating layer prepared by the current process; 2. The cyanide-free cadmium-iron alloy plating solution and electroplating process disclosed in the present invention fill the gap in the domestic market for electroplating cadmium-iron alloys. DETAILED DESCRIPTION

[0015] In order to better understand the present invention, the present invention is further specifically described below through the following examples, but it should not be understood as a limitation of the present invention. Some non-essential improvements and adjustments made by technicians in this field based on the above invention content are also considered to fall within the protection scope of the present invention.

[0016] A cyanide-free cadmium iron alloy plating solution and electroplating process, comprising preparing a cyanide-free cadmium iron alloy plating complexing agent, a leveling agent, a stabilizer, preparing a cyanide-free cadmium iron alloy plating solution, pre-treating a plated workpiece, cyanide-free cadmium iron alloy plating, and passivation.

[0017] Preferably, the leveling agent comprises 5-10 g / L of trimercapto-s-triazine, 30-60 g / L of organic amine epoxy derivative, and 5-10 g / L of sodium hydroxide. According to the formula requirements, sodium hydroxide is dissolved in water, and trimercapto-s-triazine is added, stirred to dissolve, and then the organic amine epoxy derivative is added, and water is added to the required volume to obtain the leveling agent.

[0018] Preferably, the stabilizer comprises sodium glucoheptanoate and sodium hydrogen succinate, and the mass ratio of sodium glucoheptanoate to sodium hydrogen succinate is 1:(2-3). Sodium glucoheptanoate and sodium hydrogen succinate are mixed together according to the formula ratio requirements, and stirred evenly to obtain the stabilizer.

[0019] 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). Nitrilotriacetic acid, sulfosalicylic acid, and malic acid are mixed together according to the formula ratio and stirred evenly to obtain the complexing agent.

[0020] Preferably, 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-diethyl propargylamine, N,N-diethyl propargylamine formate and N,N-diethyl propargylamine sulfate. 30 kg of isopropanol 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.

[0021] Preferably, 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 component D, and component D is consistent with component C in the brightener; 5-8kg of polyacrylamide with a molecular weight less than 8000, 2-5kg of condensate of ethylenediamine or dimethylpropylamine and epichlorohydrin, 3-8kg of sodium salt of 2-ethylhexyl sulfate, and 3-6kg of component D are added to 70kg of water, stirred to dissolve, and water is added to 100L to obtain the auxiliary agent.

[0022] Preferably, the plating solution is prepared as follows: a) Add 4 / 5 of water into the plating tank according to the volume of the plating solution, add sodium hydroxide, potassium chloride and complexing agent according to the process requirements, the mass ratio of sodium hydroxide to complexing agent is 1:2, and stir to dissolve the above substances; b) adding cadmium chloride and ferrous chloride tetrahydrate according to the process requirements, and stirring until the solid matter is dissolved; c) Add leveling agent, brightener, auxiliary agent, and stabilizer according to the process requirements, stir until the stabilizer is completely dissolved, adjust the pH of the plating solution to between 6 and 8 with a 10% sodium hydroxide solution, add water to the specified volume, and keep the temperature at 0.05 to 0.1A / dm 2 Electrolyze for 1 to 8 hours at this current density.

[0023] The existing pre-treatment process is used to remove oil, rust and activate the plated workpiece.

[0024] After the workpiece to be plated is pre-treated, the cyanide-free cadmium-iron alloy electroplating process of the present invention is used to prepare a cadmium-iron alloy coating, and the thickness of the cadmium-iron alloy coating is preferably 8 to 24 μm.

[0025] The cyanide-free cadmium iron alloy plating solution and electroplating process include 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 The cathode moves 2 to 4 m / min, the anode is made of a cadmium plate with a mass fraction of 99.97%, the area ratio of the cathode to the anode is 2:(0.7 to 1.3), and a filter is used to circulate and filter the plating solution during production.

[0026] Preferably, 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.

[0027] The workpiece is plated with cadmium iron alloy and then a passivation layer is prepared by using the current hexavalent chromium passivation process.

[0028] Preferably, the passivation layer is prepared using HC-5 high protection low chrome color passivator from Chaobang Chemical: the volume concentration of HC-5 high protection low chrome 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 15s, and weak air stirring or workpiece swinging is used.

[0029] Preferably, the passivation layer is prepared using Chaobang Chemical's OVG-31 military green passivation process: OVG-31 military green passivator 80-120 mL / L, passivation solution pH 1.0-1.6, passivation temperature 20-30°C, air stirring or swinging the plated piece, and passivation time 30-90 s.

[0030] Embodiment 1: A cyanide-free cadmium iron alloy plating solution and electroplating process, comprising the preparation of a cyanide-free cadmium iron alloy plating additive, the preparation of a cyanide-free cadmium iron alloy plating solution, pretreatment of steel parts, cyanide-free cadmium iron alloy plating, and passivation.

[0031] 1. Preparation of cyanide-free cadmium iron alloy electroplating additives: The cyanide-free cadmium iron alloy electroplating additives include a leveler, a stabilizer, a complexing agent, a brightener, and an auxiliary agent.

[0032] 1) Prepare leveling agent: The leveling agent includes 7.5 g / L of trimercapto-s-triazine, 45 g / L of an organic amine epoxy derivative with a product model of GDX sold by Sefik New Materials Co., Ltd., and 7.5 g / L of sodium hydroxide. According to the formula requirements, sodium hydroxide is dissolved in water, and trimercapto-s-triazine is added, stirred to dissolve, and then the organic amine epoxy derivative is added, and water is added to the required volume to obtain the leveling agent.

[0033] 2) Preparation of stabilizer: The stabilizer includes sodium glucoheptanoate and sodium hydrogen succinate, and the mass ratio of sodium glucoheptanoate to sodium hydrogen succinate is 1:2.5. Sodium glucoheptanoate and sodium hydrogen succinate are mixed together according to the formula ratio requirements, and stirred evenly to obtain the stabilizer.

[0034] 3) Preparation of complexing agent: The complexing agent includes nitrilotriacetic acid, sulfosalicylic acid, and malic acid, and the mass ratio of nitrilotriacetic acid, sulfosalicylic acid, and malic acid is 3:1.5:5. Nitrilotriacetic acid, sulfosalicylic acid, and malic acid are mixed together according to the formula ratio and stirred evenly to obtain the complexing agent.

[0035] 4) Prepare brightener: 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. 30kg of isopropanol is added to 40kg of water and mixed evenly, 5.5kg of component A, 4kg of component B and 8kg of component C are added, stirred to dissolve, and water is added to 100L to obtain the brightener.

[0036] 5) Preparation of auxiliary agents: 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; 6.5 kg of polyacrylamide with a molecular weight less than 8000, 3.5 kg of a condensate of ethylenediamine or dimethylpropylamine and epichlorohydrin, 5.5 kg of sodium salt of 2-ethylhexyl sulfate, and 4.5 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.

[0037] 6) Preparation of cyanide-free cadmium iron alloy plating solution: The cyanide-free cadmium iron alloy plating solution is prepared as follows: a) Add 4 / 5 of water into the plating tank according to the volume of the plating solution, add sodium hydroxide, potassium chloride and complexing agent according to the process requirements, the mass ratio of sodium hydroxide to complexing agent is 1:2, and stir to dissolve the above substances; b) adding cadmium chloride and ferrous chloride tetrahydrate according to the process requirements, and stirring until the solid matter is dissolved; c) Add leveling agent, brightener, auxiliary agent, and stabilizer according to the process requirements, stir until the stabilizer is completely dissolved, adjust the pH of the plating solution to 7 with a 10% sodium hydroxide solution, add water to the specified volume, and electrolyze for 4 hours at a current density of 0.08A / dm2.

[0038] 2. Pre-treatment: The current pre-treatment process is used to treat steel parts with "chemical degreasing → water washing → acid washing → water washing → ultrasonic degreasing → water washing → alkaline anodic electrolytic degreasing → water washing → activation → water washing".

[0039] 3. Cadmium-plated iron alloy: After the steel parts are pre-treated, the cyanide-free cadmium-iron alloy electroplating process of the present invention is adopted to prepare the cadmium-iron alloy coating, and the coating thickness is 12 μm.

[0040] Cadmium chloride 30g / L, ferrous chloride tetrahydrate 5g / L, potassium chloride 120g / L, complexing agent 120g / L, leveling agent 2.0mL / L, brightener 2.0mL / L, auxiliary agent 28mL / L, stabilizer 30g / L, plating solution pH 7, plating tank temperature 28℃, cathode current density 1.0A / dm2, cathode movement 3m / min, anode is made of cadmium plate with a mass fraction of 99.97%, the area ratio of cathode to anode is 2:1, and a filter is used to circulate and filter the plating solution during production.

[0041] During production, 30% by mass of ferrous chloride tetrahydrate solution is added to the plating tank to keep its mass concentration within the process range.

[0042] 4. Passivation: After the steel parts are plated with cadmium iron alloy, the hexavalent chromium color passivation layer is prepared using Chaobang Chemical's HC-5 high protection low chromium color passivator.

[0043] The volume concentration of HC-5 high protection low chrome color passivator is 3%, the passivation temperature is 28℃, the pH of the passivation solution is 1.6, the passivation time is 8s, and the workpiece swings.

[0044] The specific process is "1.5% by volume nitric acid polishing → water washing → passivation → water washing → drain after leaving the tank → use high-pressure air to blow away the residual water on the surface of the plated part".

[0045] 5. Drying: After passivation, the steel parts are dried at 58°C for 10 minutes.

[0046] Embodiment 2: A cyanide-free cadmium iron alloy plating solution and electroplating process, comprising the preparation of a cyanide-free cadmium iron alloy plating additive, the preparation of a cyanide-free cadmium iron alloy plating solution, pretreatment of steel parts, cyanide-free cadmium iron alloy plating, and passivation.

[0047] 1. Preparation of cyanide-free cadmium iron alloy electroplating additives: The cyanide-free cadmium iron alloy electroplating additives include a leveler, a stabilizer, a complexing agent, a brightener, and an auxiliary agent.

[0048] 1) Prepare leveling agent: The leveling agent includes 7.5 g / L of trimercapto-s-triazine, 45 g / L of an organic amine epoxy derivative with a product model of GDX sold by Sefik New Materials Co., Ltd., and 7.5 g / L of sodium hydroxide. According to the formula requirements, sodium hydroxide is dissolved in water, and trimercapto-s-triazine is added, stirred to dissolve, and then the organic amine epoxy derivative is added, and water is added to the required volume to obtain the leveling agent.

[0049] 2) Preparation of stabilizer: The stabilizer includes sodium glucoheptanoate and sodium hydrogen succinate, and the mass ratio of sodium glucoheptanoate to sodium hydrogen succinate is 1:2.5. Sodium glucoheptanoate and sodium hydrogen succinate are mixed together according to the formula ratio requirements, and stirred evenly to obtain the stabilizer.

[0050] 3) Preparation of complexing agent: The complexing agent includes nitrilotriacetic acid, sulfosalicylic acid, and malic acid, and the mass ratio of nitrilotriacetic acid, sulfosalicylic acid, and malic acid is 3:1.5:5. Nitrilotriacetic acid, sulfosalicylic acid, and malic acid are mixed together according to the formula ratio and stirred evenly to obtain the complexing agent.

[0051] 4) Prepare brightener: 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. 30kg of isopropanol is added to 40kg of water and mixed evenly, 5.5kg of component A, 4kg of component B and 8kg of component C are added, stirred to dissolve, and water is added to 100L to obtain the brightener.

[0052] 5) Preparation of auxiliary agents: 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; 6.5 kg of polyacrylamide with a molecular weight less than 8000, 3.5 kg of a condensate of ethylenediamine or dimethylpropylamine and epichlorohydrin, 5.5 kg of sodium salt of 2-ethylhexyl sulfate, and 4.5 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.

[0053] 6) Preparation of cyanide-free cadmium iron alloy plating solution: The cyanide-free cadmium iron alloy plating solution is prepared as follows: a) Add 4 / 5 of water into the plating tank according to the volume of the plating solution, add sodium hydroxide, potassium chloride and complexing agent according to the process requirements, the mass ratio of sodium hydroxide to complexing agent is 1:2, and stir to dissolve the above substances; b) adding cadmium chloride and ferrous chloride tetrahydrate according to the process requirements, and stirring until the solid matter is dissolved; c) Add leveling agent, brightener, auxiliary agent, and stabilizer according to the process requirements, stir until the stabilizer is completely dissolved, adjust the pH of the plating solution to 7 with a 10% sodium hydroxide solution, add water to the specified volume, and electrolyze for 2 hours at a current density of 0.1A / dm2.

[0054] 2. Pre-treatment: The current pre-treatment process is used to treat steel parts with "chemical degreasing → water washing → acid washing → water washing → ultrasonic degreasing → water washing → alkaline anodic electrolytic degreasing → water washing → activation → water washing".

[0055] 3. Cadmium-plated iron alloy: After the steel parts are pre-treated, the cyanide-free cadmium-iron alloy electroplating process of the present invention is adopted to prepare the cadmium-iron alloy coating, and the coating thickness is 12 μm.

[0056] Cadmium chloride 35g / L, ferrous chloride tetrahydrate 6g / L, potassium chloride 140g / L, complexing agent 140g / L, leveling agent 2.0mL / L, brightener 2.0mL / L, auxiliary agent 28mL / L, stabilizer 35g / L, plating solution pH 8, plating tank temperature 20℃, cathode current density 1.0A / dm2, cathode movement 3m / min, anode is made of cadmium plate with a mass fraction of 99.97%, the area ratio of cathode to anode is 2:2, and a filter is used to circulate and filter the plating solution during production.

[0057] During production, 30% by mass of ferrous chloride tetrahydrate solution is added to the plating tank to keep its mass concentration within the process range.

[0058] 4. Passivation: After the steel parts are plated with cadmium iron alloy, the hexavalent chromium color passivation layer is prepared using Chaobang Chemical's HC-5 high protection low chromium color passivator.

[0059] The volume concentration of HC-5 high protection low chrome color passivator is 4%, the passivation temperature is 20℃, the pH of the passivation solution is 1.2, the passivation time is 6s, and the workpiece swings.

[0060] The specific process is "1.5% by volume nitric acid polishing → water washing → passivation → water washing → drain after leaving the tank → use high-pressure air to blow away the residual water on the surface of the plated part".

[0061] 5. Drying: After passivation, the steel parts are dried at 60℃ for 10 minutes.

[0062] Embodiment 3: A cyanide-free cadmium iron alloy plating solution and electroplating process, comprising the preparation of a cyanide-free cadmium iron alloy plating additive, the preparation of a cyanide-free cadmium iron alloy plating solution, pretreatment of steel parts, cyanide-free cadmium iron alloy plating, and passivation.

[0063] 1. Preparation of cyanide-free cadmium iron alloy electroplating additives: The cyanide-free cadmium iron alloy electroplating additives include a leveler, a stabilizer, a complexing agent, a brightener, and an auxiliary agent.

[0064] 1) Prepare leveling agent: The leveling agent includes 7.5 g / L of trimercapto-s-triazine, 45 g / L of an organic amine epoxy derivative with a product model of GDX sold by Sefik New Materials Co., Ltd., and 7.5 g / L of sodium hydroxide. According to the formula requirements, sodium hydroxide is dissolved in water, and trimercapto-s-triazine is added, stirred to dissolve, and then the organic amine epoxy derivative is added, and water is added to the required volume to obtain the leveling agent.

[0065] 2) Preparation of stabilizer: The stabilizer includes sodium glucoheptanoate and sodium hydrogen succinate, and the mass ratio of sodium glucoheptanoate to sodium hydrogen succinate is 1:2.5. Sodium glucoheptanoate and sodium hydrogen succinate are mixed together according to the formula ratio requirements, and stirred evenly to obtain the stabilizer.

[0066] 3) Preparation of complexing agent: The complexing agent includes nitrilotriacetic acid, sulfosalicylic acid, and malic acid, and the mass ratio of nitrilotriacetic acid, sulfosalicylic acid, and malic acid is 3:1.5:5. Nitrilotriacetic acid, sulfosalicylic acid, and malic acid are mixed together according to the formula ratio and stirred evenly to obtain the complexing agent.

[0067] 4) Prepare brightener: 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. 30kg of isopropanol is added to 40kg of water and mixed evenly, 5.5kg of component A, 5kg of component B and 8kg of component C are added, stirred to dissolve, and water is added to 100L to obtain the brightener.

[0068] 5) Preparation of auxiliary agents: 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; 7.5 kg of polyacrylamide with a molecular weight less than 8000, 3.5 kg of a condensate of ethylenediamine or dimethylpropylamine and epichlorohydrin, 5.5 kg of sodium salt of 2-ethylhexyl sulfate, and 4.5 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.

[0069] 6) Preparation of cyanide-free cadmium iron alloy plating solution: The cyanide-free cadmium iron alloy plating solution is prepared as follows: a) Add 4 / 5 of water into the plating tank according to the volume of the plating solution, add sodium hydroxide, potassium chloride and complexing agent according to the process requirements, the mass ratio of sodium hydroxide to complexing agent is 1:2, and stir to dissolve the above substances; b) adding cadmium chloride and ferrous chloride tetrahydrate according to the process requirements, and stirring until the solid matter is dissolved; c) Add leveling agent, brightener, auxiliary agent, and stabilizer according to the process requirements, stir until the stabilizer is completely dissolved, adjust the pH of the plating solution to 6.2 with a 10% sodium hydroxide solution, add water to the specified volume, and electrolyze for 6 hours at a current density of 0.05A / dm2.

[0070] 2. Pre-treatment: The current pre-treatment process is used to treat steel parts with "chemical degreasing → water washing → acid washing → water washing → ultrasonic degreasing → water washing → alkaline anodic electrolytic degreasing → water washing → activation → water washing".

[0071] 3. Cadmium-plated iron alloy: After pre-treatment of the steel parts, the cyanide-free cadmium-iron alloy electroplating process of the present invention is adopted to prepare the cadmium-iron alloy coating, and the coating thickness is 12 μm.

[0072] Cadmium chloride 25g / L, ferrous chloride tetrahydrate 4g / L, potassium chloride 100g / L, complexing agent 100g / L, leveling agent 2.0mL / L, brightener 2.0mL / L, auxiliary agent 28mL / L, stabilizer 25g / L, plating solution pH 6.2, plating tank temperature 35°C, cathode current density 1.0A / dm2, cathode movement 3m / min, anode is made of cadmium plate with a mass fraction of 99.97%, the area ratio of cathode to anode is 2:1, and a filter is used to circulate and filter the plating solution during production.

[0073] During production, 30% by mass of ferrous chloride tetrahydrate solution is added to the plating tank to keep its mass concentration within the process range.

[0074] 4. Passivation: After the steel parts are plated with cadmium iron alloy, the military green passivation layer is prepared using Chaobang Chemical's OVG-31 military green passivation process.

[0075] OVG-31 military green passivator 80mL / L, passivation solution pH 1.6, passivation temperature 25℃, swing plated parts, passivation time 90s.

[0076] The specific process is "1.5% by volume nitric acid polishing → water washing → passivation → water washing → drain after leaving the tank → use high-pressure air to blow away the residual water on the surface of the plated part".

[0077] 5. Drying: After passivation, the steel parts are dried at 55°C for 10 minutes.

[0078] Embodiment 4: A cyanide-free cadmium iron alloy plating solution and electroplating process, comprising the preparation of a cyanide-free cadmium iron alloy plating additive, the preparation of a cyanide-free cadmium iron alloy plating solution, pretreatment of steel parts, cyanide-free cadmium iron alloy plating, and passivation.

[0079] 1. Preparation of cyanide-free cadmium iron alloy electroplating additives: The cyanide-free cadmium iron alloy electroplating additives include a leveler, a stabilizer, a complexing agent, a brightener, and an auxiliary agent.

[0080] 1) Prepare leveling agent: The leveling agent includes 7.5 g / L of trimercapto-s-triazine, 45 g / L of an organic amine epoxy derivative with a product model of GDX sold by Sefik New Materials Co., Ltd., and 7.5 g / L of sodium hydroxide. According to the formula requirements, sodium hydroxide is dissolved in water, and trimercapto-s-triazine is added, stirred to dissolve, and then the organic amine epoxy derivative is added, and water is added to the required volume to obtain the leveling agent.

[0081] 2) Preparation of stabilizer: The stabilizer includes sodium glucose heptanoate and sodium hydrogen succinate, the mass ratio of sodium glucose heptanoate to sodium hydrogen succinate is 1:2.5, and the sodium glucose heptanoate and sodium hydrogen succinate are mixed together according to the formula ratio requirements and stirred evenly to obtain the stabilizer.

[0082] 3) Preparation of complexing agent: The complexing agent includes nitrilotriacetic acid, sulfosalicylic acid, and malic acid, and the mass ratio of nitrilotriacetic acid, sulfosalicylic acid, and malic acid is 3:1.5:5. Nitrilotriacetic acid, sulfosalicylic acid, and malic acid are mixed together according to the formula ratio and stirred evenly to obtain the complexing agent.

[0083] 4) Prepare brightener: 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. 30kg of isopropanol is added to 40kg of water and mixed evenly, 5.5kg of component A, 4kg of component B and 8kg of component C are added, stirred to dissolve, and water is added to 100L to obtain the brightener.

[0084] 5) Preparation of auxiliary agents: 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 a D component, wherein the D component is consistent with the C component in the brightener; 6.5 kg of polyacrylamide with a molecular weight 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 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.

[0085] 6) Preparation of cyanide-free cadmium iron alloy plating solution: The cyanide-free cadmium iron alloy plating solution is prepared as follows: a) Add 4 / 5 of water into the plating tank according to the volume of the plating solution, add sodium hydroxide, potassium chloride and complexing agent according to the process requirements, the mass ratio of sodium hydroxide to complexing agent is 1:2, and stir to dissolve the above substances; b) adding cadmium chloride and ferrous chloride tetrahydrate according to the process requirements, and stirring until the solid matter is dissolved; c) Add leveling agent, brightener, auxiliary agent, and stabilizer according to the process requirements, stir until the stabilizer is completely dissolved, adjust the pH of the plating solution to between 7.5 with a 10% sodium hydroxide solution, add water to the specified volume, and electrolyze at a current density of 0.07A / dm2 for 5 hours.

[0086] 2. Pre-treatment: The current pre-treatment process is used to treat steel parts with "chemical degreasing → water washing → acid washing → water washing → ultrasonic degreasing → water washing → alkaline anodic electrolytic degreasing → water washing → activation → water washing".

[0087] 3. Cadmium-plated iron alloy: After the steel parts are pre-treated, the cyanide-free cadmium-iron alloy electroplating process of the present invention is adopted to prepare the cadmium-iron alloy coating, and the coating thickness is 12 μm.

[0088] Cadmium chloride 33g / L, ferrous chloride tetrahydrate 5.7g / L, potassium chloride 135g / L, complexing agent 135g / L, leveling agent 2.0mL / L, brightener 2.0mL / L, auxiliary agent 28mL / L, stabilizer 33g / L, plating solution pH 7.7, plating tank temperature 28℃, cathode current density 1.0A / dm2, cathode movement 3m / min, anode is made of cadmium plate with a mass fraction of 99.97%, the area ratio of cathode to anode is 2:1, and a filter is used to circulate and filter the plating solution during production.

[0089] During production, 30% by mass of ferrous chloride tetrahydrate solution is added to the plating tank to keep its mass concentration within the process range.

[0090] 4. Passivation: After the steel parts are plated with cadmium iron alloy, the military green passivation layer is prepared using Chaobang Chemical's OVG-31 military green passivation process.

[0091] OVG-31 military green passivator 120mL / L, passivation solution pH 1.2, passivation temperature 20℃, air stirring or swinging the plated parts, passivation time 40s.

[0092] The specific process is "1.5% by volume nitric acid polishing → water washing → passivation → water washing → drain after leaving the tank → use high-pressure air to blow away the residual water on the surface of the plated part".

[0093] 5. Drying: After passivation, the steel parts are dried at 57°C for 10 minutes.

[0094] Test Example 1: The cadmium iron alloy gold color passivation samples on the steel surface prepared in Example 1 and Example 2 were subjected to an acetic acid salt spray test for 520 hours in accordance with GB / T10125-2021 "Artificial atmosphere corrosion test salt spray test", and there was no white rust on the surface of the samples. The cadmium iron alloy military green passivation samples on the steel surface prepared in Example 3 and Example 4 were subjected to an acetic acid salt spray test for 550 hours in accordance with GB / T 10125-2021 "Artificial atmosphere corrosion test salt spray test", and there was no white rust on the surface of the samples. The cyanide-free cadmium iron alloy coating prepared by the present invention has excellent corrosion resistance.

[0095] Test Example 2: According to the present invention, a cyanide-free cadmium iron alloy plating solution is prepared: Cadmium chloride 30g / L, complexing agent 130g / L, leveling agent 2.0mL / L, brightening agent 2.0mL / L, auxiliary agent 28mL / L, stabilizer 30g / L, plating solution pH is 7. Compared with the cyanide-free cadmium iron alloy plating solution of the present invention, the configured plating solution does not contain iron salt, and the prepared coating is a cadmium plating layer.

[0096] According to the process and coating thickness requirements of Example 1 and Example 3, cadmium-plated color passivation and military green passivation samples on the steel surface were prepared, and the acetate spray test was carried out according to GB / T 10125-2021 "Artificial atmosphere corrosion test salt spray test". The color passivation sample had no white rust after 450 hours of acetate spray test, and the military green passivation sample had no white rust after 480 hours. Comparing Test Example 1 with Test Example 2, it can be seen that the salt spray resistance of the cadmium-iron alloy coating is significantly higher than that of the cadmium coating.

[0097] Test Example 3: The cadmium iron alloy gold color passivation and military green color passivation samples on the steel surface 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 environmental test requirements.

[0098] Test example 4: The cadmium iron alloy gold color passivation and military green color passivation samples on the steel surface prepared in Example 1, Example 2, Example 3, and Example 4 were tested for the bonding strength of the coating by the thermal shock method in accordance with GB / T 5270-2005 "Review of test methods for adhesion strength of electrodeposited and chemically deposited metal coatings on metal substrates". The samples were placed in a heating furnace and heated to 300°C for 30 minutes. After being taken out, they were immediately placed in water at room temperature for cooling. There was no blistering or shedding of the coating, and its bonding strength met the standard requirements.

[0099] Test Example 5: According to the present invention, a cyanide-free cadmium iron alloy plating solution is prepared: Cadmium chloride 30g / L, ferrous chloride tetrahydrate 5g / L, potassium chloride 120g / L, complexing agent 130g / L, leveling agent 2.0mL / L, brightener 2.0mL / L, auxiliary agent 28mL / L, stabilizer 30g / L, plating solution pH is 7.

[0100] A 267mL Hull cell experiment was conducted, with the coated titanium plate as the anode, at room temperature, and each test piece was plated at 0.5A for 1h. 1.2g of cadmium chloride and 0.2g of ferrous chloride tetrahydrate were added for each plated test piece, and 0.1mL of leveling agent, 0.1mL of brightener, 0.1mL of auxiliary agent, 1.2g of complexing agent, and 0.1g of stabilizer were added for each plated test piece. After continuous plating for 24h, the cadmium-iron alloy coating on the test piece had a normal appearance, and there was no suspended matter in the plating solution.

[0101] Test Example 6: Prepare the following cyanide-free cadmium iron alloy plating solution: Cadmium chloride 30g / L, ferrous chloride tetrahydrate 5g / L, potassium chloride 120g / L, complexing agent 130g / L, leveling agent 2.0mL / L, brightener 2.0mL / L, auxiliary agent 28mL / L, and the pH value of the plating solution is 7. Compared with the cadmium-iron alloy plating solution of the present invention, no stabilizer is added to the prepared plating solution.

[0102] A 267mL Hertz test was performed, operated at room temperature, with a coated titanium plate as an anode, and operated at room temperature. Each test piece was plated at 0.5A for 1h. 1.2g of cadmium chloride and 0.2g of ferrous chloride tetrahydrate were added to each plated test piece, and 0.1mL of a leveling agent, 0.1mL of a brightener, 0.1mL of an auxiliary agent, and 1.2g of a complexing agent were added to each plated test piece. After 8h of continuous plating, brown iron precipitates appeared in the plating solution and were suspended in the plating solution, and the cadmium-iron alloy coating on the test piece had granular crystals. It can be seen from the comparison between Test Example 5 and Test Example 6 that the stabilizer in the cyanide-free cadmium-iron alloy plating solution of the present invention has the effect of stabilizing the performance of the plating solution.

[0103] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A cyanide-free cadmium-iron alloy plating solution, characterized in that: It includes the following components and contents: 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; The leveling agent includes 5-10 g / L of trimercapto-s-triazine, 30-60 g / L of organic amine epoxy derivative, and 5-10 g / L of sodium hydroxide; The stabilizer includes sodium gluconate and sodium hydrogen succinate, and the mass ratio of sodium gluconate to sodium hydrogen succinate is 1:(2-3); The complexing agent includes nitrilotriacetic acid, sulfosalicylic acid, and malic acid. The above components are mixed evenly to obtain the complexing agent; the mass ratio of nitrilotriacetic acid, sulfosalicylic acid, and malic acid is 3:(1-2):(4-6).

2. The cyanide-free cadmium-iron alloy plating solution according to claim 1, characterized in that: 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.

3. The cyanide-free cadmium-iron alloy plating solution according to claim 1, characterized in that: 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.

4. The cyanide-free cadmium-iron alloy plating solution according to claim 1, characterized in that The plating solution is prepared as follows: a) Add 4 / 5 of water into the plating tank according to the volume of the plating solution, add sodium hydroxide, potassium chloride and complexing agent according to the process requirements, the mass ratio of sodium hydroxide to complexing agent is 1:2, and stir to dissolve the above substances; b) Add cadmium chloride and ferrous chloride tetrahydrate according to the process requirements and stir until the solid matter is dissolved; c) Add leveling agent, brightener, auxiliary agent, and stabilizer according to the process requirements, stir until the stabilizer is completely dissolved, adjust the pH of the plating solution to between 6 and 8 with a 10% sodium hydroxide solution, add water to the specified volume, and keep the temperature at 0.05-0.1A / dm 2 Electrolyze for 1 to 8 hours at this current density.

5. A cyanide-free cadmium iron alloy electroplating process, characterized in that: 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 , the cathode moves 2 to 4 m / min.

6. The cyanide-free cadmium iron alloy electroplating process according to claim 5, characterized in that: The anode is made of cadmium plate with a mass fraction of 99.97%.

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

8. The cyanide-free cadmium iron alloy electroplating process according to claim 5, characterized in that: In production, filters are used to circulate and filter the plating solution.

9. The cyanide-free cadmium iron alloy electroplating process according to claim 5, 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.

10. The cyanide-free cadmium iron alloy electroplating process according to claim 5, characterized in that: The process includes the following steps: a) Prepare cyanide-free cadmium iron alloy plating solution; b) Pre-treat the workpiece using the current pre-treatment method; c) Cadmium iron alloy plating after workpiece pre-treatment; d) After the workpiece is plated with cadmium iron alloy, it is passivated using the current passivation process.