A trivalent chromium plating process for high-strength steel structural parts, a manufacturing process and a plated layer structure

Abstract

The application discloses a trivalent chromium plating process for high-strength steel structural parts, a process and a plated layer structure, which comprises sequentially plating cobalt-titanium alloy, cyanide-free copper, bright nickel, trivalent chromium and rare earth electrolytic protection on a high-strength steel base body. The trivalent chromium plating process composition and parameters comprise 90-130 g / L of chromium chloride hexahydrate, 80-120 g / L of potassium chloride, 100-150 g / L of ammonium chloride, 18-24 g / L of ammonium bromide, 45-50 g / L of ammonium formate, 50-60 g / L of boric acid, 8-12 mL / L of rare earth additive, 2-4 mL / L of trivalent chromium plating walking position agent, 1-3 mL / L of accelerator, 2.5-3.2 of plating solution pH value, 25-35 DEG C of plating bath temperature, 10-16 A / dm of cathode current density and moderate air agitation. 2 The hydrogen brittleness test is carried out according to HB 5067.1-2005 'Plating Process Hydrogen Brittleness Test Part 1: Mechanical Method', and the test result meets the standard requirement. The plated layer has excellent performance and good market prospect.

Description

Technical Field

[0001] This invention belongs to the field of metal surface treatment technology, specifically relating to a trivalent chromium plating process, manufacturing process and plating structure for high-strength steel structural components. Background Technology

[0002] Because high-strength structural steel suffers from hydrogen embrittlement during electroplating due to hydrogen evolution, researchers in the industry have been dedicated to studying and solving these problems. [1] Due to the specific needs of the aviation industry, hexavalent chromium hard chromium plating was previously used to prepare functional coatings for some aerospace structural components. [2] However, hexavalent chromium plating for hard chromium has low current efficiency and a large amount of hydrogen evolution during electroplating. After hexavalent chromium plating is performed on high-strength structural steel, a large amount of hydrogen inevitably seeps into the substrate. Therefore, this process is not suitable for preparing low-hydrogen-embrittlement electroplating layers.

[0003] Experimental studies show that most of the hydrogen in the cadmium-titanium alloy electroplated samples of A100 steel parts exists in the coating, with only a very small amount penetrating into the substrate. [2] Some scholars in the industry believe that the titanium in the cadmium-titanium alloy coating can combine with hydrogen to form titanium trihydride, which can effectively prevent hydrogen atoms from diffusing towards the high-strength structural steel substrate.

[0004] References: [1]. Xiang Keyou, Lan Yuliang, Gao Ronglong, et al. Research progress on hydrogen embrittlement sensitivity of zinc-nickel alloy plating on high-strength steel parts [J]. Electroplating & Finishing, 2024, 46(8): 51-59. [2]. Yu Bo, Tang Zhihui, Peng Chao, et al. Effect of cyanide-free electroplated cadmium-titanium alloy on hydrogen embrittlement performance of steel substrate [J]. Electroplating & Finishing, 2011, 33(11): 1-4. Summary of the Invention

[0005] To overcome the problem of hydrogen embrittlement during electroplating of high-strength steel structural components, this invention provides a trivalent chromium plating process, procedure, and plating structure for high-strength steel structural components. To achieve the above objective, this invention adopts the following technical solution: A trivalent chromium plating process for high-strength steel structural components includes the following process parameters: Chromium chloride hexahydrate 90–130 g / L, potassium chloride 80–120 g / L, ammonium chloride 100–150 g / L, ammonium bromide 18–24 g / L, ammonium formate 45–50 g / L, boric acid 50–60 g / L, rare earth additives 8–12 mL / L, trivalent chromium plating leveling agent 2–4 mL / L, accelerator 1–3 mL / L, plating bath pH 2.5–3.2, plating bath temperature 25–35℃, cathode current density 10–16 A / dm³ 2 Medium air mixing; The rare earth additives contain 30-70 g / L lanthanum chloride heptahydrate and 30-70 g / L praseodymium chloride heptahydrate, which are used to refine the grains of the trivalent chromium plating layer and improve its corrosion resistance. The trivalent chromium plating leveling agent contains 40-80 g / L of vanadium oxysulfate and 100-150 g / L of concentrated sulfuric acid; The accelerator contains 15-25 g / L of NORFOX PE-600 acid ethoxylated alcohol phosphate.

[0006] In some embodiments, the rare earth additive is prepared as follows: based on the volume of the rare earth additive to be prepared, 4 / 5 of the pure water is added to the reaction vessel, and lanthanum chloride heptahydrate and praseodymium chloride heptahydrate are added under stirring according to the formula requirements. The mixture is stirred until the solids are completely dissolved, and then pure water is added to the required volume. The mixture is stirred evenly to obtain the rare earth additive.

[0007] In some embodiments, based on the volume of the prepared trivalent chromium plating leveling agent, 4 / 5 of the pure water is added to the reaction vessel, concentrated sulfuric acid is slowly added according to the formula requirements, and then vanadium oxysulfate is added under stirring until the vanadium oxysulfate dissolves. Pure water is then added to the required volume, and the mixture is stirred evenly to obtain the trivalent chromium plating leveling agent.

[0008] A trivalent chromium plating process for high-strength steel structural components includes the following steps: (1) Pretreatment of high-strength steel structural components, including degreasing and sulfuric acid anodic electrolytic activation; (2) After the high-strength steel structural components are pretreated, a cobalt-titanium alloy coating is prepared by a cobalt-titanium alloy plating process. (3) After high-strength steel structural components are plated with cobalt-titanium alloy, a cyanide-free copper plating layer is prepared using a cyanide-free copper plating process. (4) After cyanide-free copper plating, high-strength steel structural components are prepared with a bright nickel plating process. (5) After high-strength steel structural components are plated with bright nickel, a trivalent chromium plating layer is prepared using a trivalent chromium plating process. (6) After trivalent chromium plating, high-strength steel structural components are prepared with rare earth electrolytic protection process to prepare rare earth electrolytic protective film. (7) High-strength steel structural components undergo hydrogen removal treatment after rare earth electrolytic protection; The cobalt-titanium alloy plating process includes the following process parameters: Cobalt sulfate heptahydrate 160–200 g / L, potassium fluorotitanate 8–12 g / L, sodium fluoride 2–8 g / L, sodium sulfate 80–120 g / L, sodium hydrogen succinate 30–50 g / L, cobalt-titanium alloy leveling agent 8–12 mL / L, plating bath pH 3.8–4.4, plating bath temperature 20–35℃, cathode current density 1–2 A / dm³ 2The cathode moves at a speed of 4-6 m / min. Cobalt particles are used as the anode. The cobalt particles are loaded into a titanium anode basket and covered with an anode bag. The area ratio of the anode to the cathode is (3-6):1. The cobalt-titanium alloy positioning agent comprises 20-30 g / L of the condensation reaction product of salicylic acid and epichlorohydrin, 80-120 g / L of sodium saccharin, 200-300 mL / L of sodium propylene sulfonate with a mass fraction of 35%, 4-8 mL / L of NORFOX PE-600 acid ethoxylated alcohol phosphate, and 140-160 mL / L of ethanol.

[0009] In some embodiments, the cyanide-free copper plating process employs a polymeric thiocyanate copper plating process: Polymeric cuprous thiocyanate 18–24 g / L, polymeric sodium thiocyanate 130–170 g / L, sodium hydroxyethylidene diphosphonate 20–30 g / L, copper plating brightener 8–12 mL / L, plating bath pH 12–13, plating bath temperature 30–40℃, cathode current density 0.5–1.5 A / dm³ 2 The cathode moves at a speed of 3-5 m / min. Oxygen-free electrolytic copper particles are used as the anode. The copper particles are loaded into a titanium anode basket. The area ratio of the anode to the cathode is (3-4):1. The anode moves at a speed of 3-5 m / min.

[0010] A trivalent chromium plating structure for a high-strength steel structural component includes a high-strength steel substrate and, sequentially prepared from the inside out, a cobalt-titanium alloy plating layer, a cyanide-free copper plating layer, a bright nickel plating layer, a trivalent chromium plating layer, and a rare earth electrolytic protective film on the high-strength steel substrate.

[0011] In some embodiments, the thickness of the cobalt-titanium alloy coating is 6–12 μm, and the mass fraction of titanium in the cobalt-titanium alloy coating is 0.5%–3%.

[0012] In some embodiments, the titanium in the cobalt-titanium alloy coating comprises 0.5% to 3% by mass, and the titanium serves to block the diffusion of hydrogen atoms toward the high-strength steel substrate.

[0013] In some embodiments, the thickness of the cyanide-free copper plating layer is 5–10 μm, the thickness of the bright nickel plating layer is 6–20 μm, and the bright nickel plating layer provides electrochemical protection for the cyanide-free copper plating layer.

[0014] In some embodiments, the thickness of the trivalent chromium plating layer is 0.4–1.2 μm.

[0015] During the trivalent chromium plating process, water electrolysis increases the pH of the plating solution on the surface of the workpiece, causing rare earth salts to hydrolyze and form a rare earth oxide film. This rare earth oxide film can effectively improve the cathodic polarization, thereby increasing the density of the trivalent chromium plating layer.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The high-strength steel structural component trivalent chromium plating process, process and coating structure disclosed in this invention do not contain high coordination ability coordination agents in the cobalt titanium alloy plating bath, the plating bath current efficiency is high, and there is very little hydrogen evolution during the cobalt titanium alloy plating process, which is conducive to the preparation of low hydrogen embrittlement coating. 2. The high-strength steel structural component trivalent chromium plating process, manufacturing process and plating structure disclosed in this invention involves plating a cobalt-titanium alloy on a high-strength steel substrate. The titanium atoms in the cobalt-titanium alloy plating can react with hydrogen atoms to generate titanium trihydride compounds, thereby effectively preventing the diffusion of hydrogen atoms towards the substrate and avoiding hydrogen embrittlement of the high-strength steel substrate. 3. The high-strength steel structural component trivalent chromium plating process, manufacturing process and plating structure disclosed in this invention involves plating a cobalt-titanium alloy onto a high-strength steel substrate and then preparing other plating layers. The cobalt-titanium alloy plating layer can effectively prevent the diffusion of hydrogen atoms towards the substrate. 4. The high-strength steel structural component trivalent chromium plating process, manufacturing process and plating structure disclosed in this invention involves plating bright nickel on a cyanide-free copper plating layer. The bright nickel plating layer provides electrochemical protection to the cyanide-free copper plating layer and can effectively improve the corrosion resistance of this plating structure. 5. The high-strength steel structural parts trivalent chromium plating process, manufacturing process and plating structure disclosed in this invention improve the corrosion resistance of the trivalent chromium plating layer by adding rare earth salts to the plating solution, overcoming the defect of poor corrosion resistance of the trivalent chromium plating layer prepared by the current process. Attached Figure Description

[0017] The accompanying drawings, which are provided to further illustrate the invention and form part of this application, do not constitute an undue limitation of the invention.

[0018] In the attached diagram, Figure 1 This is a schematic diagram of the coating structure prepared in Embodiments 1, 2, 3 and 4 of the present invention. Detailed Implementation

[0019] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The illustrative embodiments and descriptions of the present invention are used to explain the present invention, but are not intended to limit the present invention.

[0020] A process, procedure, and coating structure for trivalent chromium plating of high-strength steel structural components includes high-strength steel pretreatment and the sequential preparation of a cobalt-titanium alloy coating, a cyanide-free copper plating coating, a bright nickel plating coating, a trivalent chromium plating coating, a rare earth electrolytic protective film, and hydrogen removal on the pretreated high-strength steel substrate from the inside out.

[0021] The surface of the high-strength steel structural component substrate is degreased and activated by sulfuric acid anodic electrolysis.

[0022] Preferably, the process parameters for the sulfuric acid anodic electrolytic activation are as follows: Sulfuric acid concentration of 180–260 g / L, operating at room temperature, with the workpiece to be plated as the anode, and an anode current density of 0.6–1.2 A / dm³. 2 Electrolysis for 30–50 seconds.

[0023] After pretreatment, the high-strength steel structural components are coated with a cobalt-titanium alloy using the cobalt-titanium alloy plating process of this invention. Preferably, the thickness of the cobalt-titanium alloy plating is 6–12 μm.

[0024] Cobalt sulfate heptahydrate 160–200 g / L, potassium fluorotitanate 8–12 g / L, sodium fluoride 2–8 g / L, sodium sulfate 80–120 g / L, sodium hydrogen succinate 30–50 g / L, cobalt-titanium alloy leveling agent 8–12 mL / L, plating bath pH 3.8–4.4, plating bath temperature 20–35℃, cathode current density 1–2 A / dm³ 2 The cathode moves at a speed of 4-6 m / min. Cobalt particles are used as the anode. The cobalt particles are loaded into a titanium anode basket and covered with an anode bag. The area ratio of the anode to the cathode is (3-6):1.

[0025] Preferably, the cobalt-titanium alloy positioning agent comprises 20-30 g / L of the condensation reaction product of salicylic acid and epichlorohydrin, 80-120 g / L of sodium saccharin, 200-300 mL / L of sodium propylene sulfonate with a mass fraction of 35%, 4-8 mL / L of NORFOX PE-600 acid ethoxylated alcohol phosphate, and 140-160 mL / L of ethanol.

[0026] Preferably, pure water is added to the reaction vessel at half the volume of the prepared cobalt-titanium alloy positioning agent. Ethanol and the condensation reaction product of salicylic acid and epichlorohydrin are added according to the process formula requirements. The mixture is stirred evenly. Sodium saccharin, sodium propylene sulfonate (35% by mass), and acidic ethoxylated alcohol phosphate are added according to the process formula requirements. The mixture is stirred until the sodium saccharin dissolves. Then, pure water is added to the required volume.

[0027] Preferably, solid potassium fluorotitanate is added to the plating bath during production to maintain its mass concentration within the process range.

[0028] High-strength steel structural components are plated with cobalt-titanium alloy and then a cyanide-free copper plating layer is prepared using a polymeric thiocyanate copper plating process developed by Chaobang Chemical. Preferably, the thickness of the cyanide-free copper plating layer is 5–10 μm.

[0029] Polymeric cuprous thiocyanate 18–24 g / L, polymeric sodium thiocyanate 130–170 g / L, sodium hydroxyethylidene diphosphonate 20–30 g / L, copper plating brightener 8–12 mL / L, plating bath pH 12–13, plating bath temperature 30–40℃, cathode current density 0.5–1.5 A / dm³ 2 The cathode moves at a speed of 3-5 m / min. Oxygen-free electrolytic copper particles are used as the anode. The copper particles are loaded into a titanium anode basket. The area ratio of the anode to the cathode is (3-4):1. The anode moves at a speed of 3-5 m / min.

[0030] High-strength steel structural components are coated with copper without cyanide and then a bright nickel plating layer is prepared using the existing bright nickel plating process. Preferably, the thickness of the bright nickel plating layer is 6–20 μm.

[0031] Preferably, the bright nickel plating layer is prepared using the NINFEA 8002 high-leveling bright nickel electroplating process from Chaobang Chemical Co., Ltd. Nickel sulfate hexahydrate 240–300 g / L, nickel chloride hexahydrate 45–70 g / L, boric acid 37–45 g / L, NINFEA 8002 main brightener 0.6–1 mL / L, NINFEA SC-263 softener 8–15 mL / L, NINFEA AS-250 auxiliary agent 1–4 mL / L, NINFEA NI-35 wetting agent 0.2–1 mL / L, plating bath pH 4–4.6, plating bath temperature 55–65℃, cathode current density 2–6 A / dm³ 2 Anode current density 1-3 A / dm 2 The system circulates and filters 5-8 times per hour, ensuring uniform air agitation.

[0032] After high-strength steel structural components are plated with bright nickel, a trivalent chromium plating layer is prepared using the trivalent chromium plating process of this invention. Preferably, the thickness of the trivalent chromium plating layer is 0.4–1.2 μm, and the mass fraction of titanium in the cobalt-titanium alloy plating layer is 0.5%–3%.

[0033] Chromium chloride hexahydrate 90–130 g / L, potassium chloride 80–120 g / L, ammonium chloride 100–150 g / L, ammonium bromide 18–24 g / L, ammonium formate 45–50 g / L, boric acid 50–60 g / L, rare earth additives 8–12 mL / L, trivalent chromium plating leveling agent 2–4 mL / L, accelerator 1–3 mL / L, plating bath pH 2.5–3.2, plating bath temperature 25–35℃, cathode current density 10–16 A / dm³ 2 Medium air mixing.

[0034] Preferably, the rare earth additive contains 30-70 g / L lanthanum chloride heptahydrate and 30-70 g / L praseodymium chloride heptahydrate.

[0035] Preferably, the rare earth additive is prepared as follows: based on the volume of the rare earth additive to be prepared, add 4 / 5 of the pure water to the reaction vessel, add lanthanum chloride heptahydrate and praseodymium chloride heptahydrate according to the formula requirements while stirring, stir until the solids are completely dissolved, then add pure water to the required volume, and stir evenly to obtain the rare earth additive.

[0036] Preferably, the trivalent chromium plating leveling agent contains 40-80 g / L of vanadium oxysulfate and 100-150 g / L of concentrated sulfuric acid. Vanadium oxysulfate can improve the chromium plating leveling ability of trivalent chromium, and sulfuric acid is used to adjust the pH and promote the dissolution of vanadium oxysulfate.

[0037] Preferably, based on the volume of the prepared trivalent chromium plating leveling agent, 4 / 5 of the pure water is added to the reaction vessel, concentrated sulfuric acid is slowly added according to the formula requirements, then vanadium oxysulfate is added under stirring until the vanadium oxysulfate dissolves, pure water is added to the required volume, and the mixture is stirred evenly to obtain the trivalent chromium plating leveling agent.

[0038] Preferably, the accelerator comprises 15-25 g / L of NORFOX PE-600 acid ethoxylated alcohol phosphate.

[0039] After high-strength steel structural components are chrome-plated with trivalent chromium, a rare earth electrolytic protective film is prepared using a rare earth electrolytic protection process developed by Chaobang Chemical.

[0040] Cerium acetate 1–5 g / L, sodium molybdate 5–15 g / L, HEDP-2Na complexing agent 7–35 g / L, anhydrous sodium carbonate 100–150 g / L, electrolyte pH 11.5–12.5, cathode current density 0.5–1.5 A / dm³ 2 Operating at room temperature, using the plated part as the cathode and the titanium plate as the anode, electrolysis for 60–120 seconds.

[0041] High-strength steel structural components are dried using conventional drying processes after rare earth electrolytic protection.

[0042] High-strength steel structural components undergo hydrogen removal treatment after drying: plated parts are dehydrogenated at 190-200℃ for 10-24 hours.

[0043] Example 1: A process, procedure, and coating structure for trivalent chromium plating of high-strength steel structural components includes pretreatment of the high-strength steel substrate and sequential preparation of a cobalt-titanium alloy coating, a cyanide-free copper plating coating, a bright nickel plating coating, a trivalent chromium plating coating, a rare earth electrolytic protective film, and hydrogen removal on the pretreated high-strength steel substrate from the inside out.

[0044] like Figure 1As shown, a trivalent chromium plating structure for a high-strength steel structural component includes a high-strength steel substrate 1, and a cobalt-titanium alloy plating layer 2, a cyanide-free copper plating layer 3, a bright nickel plating layer 4, a trivalent chromium plating layer 5, and a rare earth electrolytic protective film 6, which are sequentially prepared from the inside to the outside on the high-strength steel substrate 1.

[0045] 1. Pre-processing: The high-strength steel structural component substrate 1 is subjected to the following process: "alkaline ultrasonic degreasing → water washing → alkaline anodic electrolytic degreasing → water washing → sulfuric acid anodic electrolytic activation → water washing".

[0046] The sulfuric acid anodic electrolytic activation includes the following process parameters: Sulfuric acid 220 g / L, room temperature operation, with the workpiece to be plated as the anode, anolyte current density 1 A / dm³ 2 Electrolysis for 40 seconds.

[0047] 2. Cobalt-plated titanium alloy: After pretreatment of high-strength steel structural components, a cobalt-titanium alloy coating 2 is prepared using the cobalt-titanium alloy plating process of the present invention. The coating thickness is 8μm, and the mass fraction of titanium in the cobalt-titanium alloy coating is 2%.

[0048] 1) Preparation of cobalt-plated titanium alloy positioning agent: The cobalt-titanium alloy positioning agent includes 25 g / L of the condensation reaction product of salicylic acid and epichlorohydrin, 100 g / L of sodium saccharin, 250 mL / L of sodium propylene sulfonate with a mass fraction of 35%, 6 mL / L of NORFOX PE-600 acidic ethoxylated alcohol phosphate, and 150 mL / L of ethanol.

[0049] Add 1 / 2 volume of pure water to the reaction vessel to prepare the cobalt-titanium alloy positioning agent. Add ethanol and the condensation reaction product of salicylic acid and epichlorohydrin according to the process formula. Stir evenly. Add sodium saccharin, sodium propylene sulfonate (35% by mass), and acidic ethoxylated alcohol phosphate according to the process formula. Stir until the sodium saccharin dissolves. Then add pure water to the required volume and stir evenly to obtain the cobalt-titanium alloy positioning agent.

[0050] 2) Cobalt-plated titanium alloy: Cobalt sulfate heptahydrate 180 g / L, potassium fluorotitanate 10 g / L, sodium fluoride 5 g / L, sodium sulfate 100 g / L, sodium hydrogen succinate 40 g / L, cobalt-titanium alloy leveling agent 10 mL / L, plating bath pH 4.1, plating bath temperature 25℃, cathode current density 1.5 A / dm³ 2 The cathode moves at a speed of 5 m / min. Cobalt particles are used as the anode. The cobalt particles are loaded into a titanium anode basket and covered with an anode bag. The area ratio of the anode to the cathode is 6:1. During production, solid potassium fluorotitanate is added to the plating tank to keep its mass concentration within the process range.

[0051] 3. Cyanide-free copper plating: After high-strength steel structural components are plated with cobalt-titanium alloy, a cyanide-free copper plating layer 3 is prepared using the polymer thiocyanate copper plating process developed by Chaobang Chemical, with a plating thickness of 8μm.

[0052] 1) Preparation of copper plating brightener: By weight, 820 parts of deionized water were added to a reaction vessel, and 80 parts of N,N'-di-n-propylethylenediamine, 15 parts of waterborne polyurethane resin, and 100 parts of GRO-70 polyacrylamide were added under stirring. The mixture was stirred until homogeneous to obtain the brightener.

[0053] 2) Plating: Polymeric cuprous thiocyanate 21 g / L, polymeric sodium thiocyanate 150 g / L, sodium hydroxyethylidene diphosphonate 25 g / L, copper plating brightener 8–12 mL / L, plating bath pH 12.5, plating bath temperature 35℃, cathode current density 1 A / dm³ 2 The cathode moves at a speed of 3-5 m / min. Oxygen-free electrolytic copper particles are used as the anode. The copper particles are loaded into a titanium anode basket. The area ratio of the anode to the cathode is 3.5:1. The anode moves at a speed of 4 m / min.

[0054] 4. Bright nickel plating: After cyanide-free copper plating, the high-strength steel structural components were coated with a bright nickel plating layer 4 using the NINFEA 8002 high-filling bright nickel electroplating process from Chaobang Chemical Co., Ltd. The plating layer thickness was 15μm.

[0055] Nickel sulfate hexahydrate 270 g / L, nickel chloride hexahydrate 58 g / L, boric acid 41 g / L, NINFEA 8002 main brightener 0.8 mL / L, NINFEA SC-263 softener 12 mL / L, NINFEA AS-250 auxiliary agent 2.5 mL / L, NINFEA NI-35 wetting agent 0.6 mL / L, plating bath pH 4.3, operating temperature 60℃, cathode current density 4 A / dm³ 2 Anode current density 2A / dm 2 The system is circulated and filtered 6 times per hour, with uniform air agitation.

[0056] 5. Trivalent chromium plating: After high-strength steel structural components are plated with bright nickel, a trivalent chromium plating layer 5 is prepared using the trivalent chromium plating process of the present invention, with a plating thickness of 0.8 μm.

[0057] 1) Preparation of rare earth additives: The rare earth additives contain 50 g / L of lanthanum chloride heptahydrate and 50 g / L of praseodymium chloride heptahydrate.

[0058] Based on the volume of the prepared rare earth additive, add 4 / 5 of the pure water to the reaction vessel, and while stirring, add lanthanum chloride heptahydrate and praseodymium chloride heptahydrate according to the formula requirements. Stir until the solids are completely dissolved, then add water to the required volume and stir evenly to obtain the rare earth additive.

[0059] 2) Preparation of trivalent chromium plating leveling agent: The trivalent chromium plating leveling agent contains 60 g / L vanadium oxysulfate and 125 g / L concentrated sulfuric acid. Vanadium oxysulfate can improve the chromium plating leveling ability of trivalent chromium, and sulfuric acid is used to adjust the pH and promote the dissolution of vanadium oxysulfate.

[0060] Calculate the volume of the trivalent chromium plating leveling agent, add 4 / 5 of the pure water to the reaction vessel, slowly add concentrated sulfuric acid according to the formula requirements, then add vanadium oxysulfate under stirring, stir until the vanadium oxysulfate dissolves, add pure water to the required volume, and stir evenly to obtain the trivalent chromium plating leveling agent.

[0061] 3) Preparation of accelerator: The accelerator contains 20 g / L of NORFOX PE-600 acidic ethoxylated alcohol phosphate ester. The accelerator is obtained by dissolving NORFOX PE-600 acidic ethoxylated alcohol phosphate ester in water according to the formulation requirements.

[0062] 4) Trivalent chromium plating: The plating solution contains 110 g / L chromium chloride hexahydrate, 100 g / L potassium chloride, 130 g / L ammonium chloride, 21 g / L ammonium bromide, 48 g / L ammonium formate, 55 g / L boric acid, 10 mL / L rare earth additives, 3 mL / L trivalent chromium plating leveling agent, 2 mL / L accelerator, a pH of 2.8, a plating bath temperature of 30℃, and a cathode current density of 13 A / dm³. 2 Medium air mixing.

[0063] 6. Rare earth electrolysis protection: After high-strength steel structural components are chrome-plated with trivalent chromium, a rare earth electrolytic protective film is prepared using a rare earth electrolytic protection process developed by Chaobang Chemical.

[0064] Cerium acetate 3 g / L, sodium molybdate 10 g / L, HEDP-2Na complexing agent 23 g / L, anhydrous sodium carbonate 125 g / L, electrolyte pH 12, cathode current density 1 A / dm³ 2 Operating at room temperature, using the plated part as the cathode and the titanium plate as the anode, electrolyzing for 90 seconds.

[0065] 7. Drying: High-strength steel structural components are dried using conventional drying processes after rare earth electrolytic protection.

[0066] 8. Hydrogen removal: High-strength steel structural components undergo hydrogen removal treatment after drying: plated parts are dehydrogenated at 195℃ for 24 hours.

[0067] Example 2: A process, procedure, and coating structure for trivalent chromium plating of high-strength steel structural components includes pretreatment of the high-strength steel substrate and sequential preparation of a cobalt-titanium alloy coating, a cyanide-free copper plating coating, a bright nickel plating coating, a trivalent chromium plating coating, a rare earth electrolytic protective film, and hydrogen removal on the pretreated high-strength steel substrate from the inside out.

[0068] like Figure 1 As shown, a trivalent chromium plating structure for a high-strength steel structural component includes a high-strength steel substrate 1, and a cobalt-titanium alloy plating layer 2, a cyanide-free copper plating layer 3, a bright nickel plating layer 4, a trivalent chromium plating layer 5, and a rare earth electrolytic protective film 6, which are sequentially prepared from the inside to the outside on the high-strength steel substrate 1.

[0069] 1. Pre-processing: The high-strength steel structural component substrate 1 is subjected to the following process: "alkaline ultrasonic degreasing → water washing → alkaline anodic electrolytic degreasing → water washing → sulfuric acid anodic electrolytic activation → water washing".

[0070] The sulfuric acid anodic electrolytic activation includes the following process parameters: Sulfuric acid 260 g / L, room temperature operation, with the workpiece to be plated as the anode, anolyte current density 0.6 A / dm³ 2 Electrolysis for 30 seconds.

[0071] 2. Cobalt-plated titanium alloy: After pretreatment of high-strength steel structural components, a cobalt-titanium alloy coating 2 is prepared using the cobalt-titanium alloy plating process of the present invention. The coating thickness is 8μm, and the mass fraction of titanium in the cobalt-titanium alloy coating is 2%.

[0072] 1) Preparation of cobalt-plated titanium alloy positioning agent: The cobalt-titanium alloy positioning agent includes 25 g / L of the condensation reaction product of salicylic acid and epichlorohydrin, 100 g / L of sodium saccharin, 250 mL / L of sodium propylene sulfonate with a mass fraction of 35%, 6 mL / L of NORFOX PE-600 acidic ethoxylated alcohol phosphate, and 150 mL / L of ethanol.

[0073] Add 1 / 2 volume of pure water to the reaction vessel to prepare the cobalt-titanium alloy positioning agent. Add ethanol and the condensation reaction product of salicylic acid and epichlorohydrin according to the process formula. Stir evenly. Add sodium saccharin, sodium propylene sulfonate (35% by mass), and acidic ethoxylated alcohol phosphate according to the process formula. Stir until the sodium saccharin dissolves. Then add pure water to the required volume and stir evenly to obtain the cobalt-titanium alloy positioning agent.

[0074] 2) Cobalt-plated titanium alloy: Cobalt sulfate heptahydrate 200 g / L, potassium fluorotitanate 12 g / L, sodium fluoride 8 g / L, sodium sulfate 120 g / L, sodium hydrogen succinate 50 g / L, cobalt-titanium alloy leveling agent 10 mL / L, plating bath pH 4.4, plating bath temperature 20℃, cathode current density 1.5 A / dm³ 2 The cathode moves at a speed of 5 m / min. Cobalt particles are used as the anode. The cobalt particles are loaded into a titanium anode basket and covered with an anode bag. The area ratio of the anode to the cathode is 5:1.

[0075] 3. Cyanide-free copper plating: After high-strength steel structural components are plated with cobalt-titanium alloy, a cyanide-free copper plating layer 3 is prepared using the polymer thiocyanate copper plating process developed by Chaobang Chemical, with a plating thickness of 8μm.

[0076] 1) Preparation of copper plating brightener: By weight, 820 parts of deionized water were added to a reaction vessel, and 80 parts of N,N'-di-n-propylethylenediamine, 15 parts of waterborne polyurethane resin, and 100 parts of GRO-70 polyacrylamide were added under stirring. The mixture was stirred until homogeneous to obtain the brightener.

[0077] 2) Plating: Polymeric cuprous thiocyanate 24 g / L, polymeric sodium thiocyanate 170 g / L, sodium hydroxyethylidene diphosphonate 30 g / L, copper plating brightener 10 mL / L, plating bath pH 12.5, plating bath temperature 30℃, cathode current density 1 A / dm³ 2 The cathode moves at a speed of 4 m / min. Oxygen-free electrolytic copper particles are used as the anode. The copper particles are loaded into a titanium anode basket. The area ratio of the anode to the cathode is 3:1. The anode moves at a speed of 4 m / min.

[0078] 4. Bright nickel plating: After cyanide-free copper plating, the high-strength steel structural components were coated with a bright nickel plating layer 4 using the NINFEA 8002 high-filling bright nickel electroplating process from Chaobang Chemical Co., Ltd. The plating layer thickness was 10μm.

[0079] Nickel sulfate hexahydrate 300 g / L, nickel chloride hexahydrate 70 g / L, boric acid 37 g / L, NINFEA 8002 main brightener 0.8 mL / L, NINFEA SC-263 softener 12 mL / L, NINFEA AS-250 auxiliary agent 2.5 mL / L, NINFEA NI-35 wetting agent 0.6 mL / L, plating bath pH 4.4, operating temperature 55℃, cathode current density 4 A / dm³ 2 Anode current density 2A / dm 2 The system is circulated and filtered 6 times per hour, with uniform air agitation.

[0080] 5. Trivalent chromium plating: After high-strength steel structural components are plated with bright nickel, a trivalent chromium plating layer 5 is prepared using the trivalent chromium plating process of the present invention, with a plating thickness of 0.8 μm.

[0081] 1) Preparation of rare earth additives: The rare earth additives contain 50 g / L of lanthanum chloride heptahydrate and 50 g / L of praseodymium chloride heptahydrate.

[0082] Based on the volume of the prepared rare earth additive, add 4 / 5 of the pure water to the reaction vessel, and while stirring, add lanthanum chloride heptahydrate and praseodymium chloride heptahydrate according to the formula requirements. Stir until the solids are completely dissolved, then add water to the required volume and stir evenly to obtain the rare earth additive.

[0083] 2) Preparation of trivalent chromium plating leveling agent: The trivalent chromium plating leveling agent contains 60 g / L vanadium oxysulfate and 125 g / L concentrated sulfuric acid. Vanadium oxysulfate can improve the chromium plating leveling ability of trivalent chromium, and sulfuric acid is used to adjust the pH and promote the dissolution of vanadium oxysulfate.

[0084] Calculate the volume of the trivalent chromium plating leveling agent, add 4 / 5 of the pure water to the reaction vessel, slowly add concentrated sulfuric acid according to the formula requirements, then add vanadium oxysulfate under stirring, stir until the vanadium oxysulfate dissolves, add pure water to the required volume, and stir evenly to obtain the trivalent chromium plating leveling agent.

[0085] 3) Preparation of accelerator: The accelerator contains 20 g / L of NORFOX PE-600 acidic ethoxylated alcohol phosphate ester. The accelerator is obtained by dissolving NORFOX PE-600 acidic ethoxylated alcohol phosphate ester in water according to the formulation requirements.

[0086] 4) Trivalent chromium plating: The plating solution contains 130 g / L chromium chloride hexahydrate, 80 g / L potassium chloride, 120 g / L ammonium chloride, 24 g / L ammonium bromide, 50 g / L ammonium formate, 50 g / L boric acid, 10 mL / L rare earth additives, 3 mL / L trivalent chromium plating leveling agent, 2 mL / L accelerator, a pH of 3.2, a plating bath temperature of 25℃, and a cathode current density of 13 A / dm³. 2 Medium air mixing.

[0087] 6. Rare earth electrolysis protection: After high-strength steel structural components are chrome-plated with trivalent chromium, a rare earth electrolytic protective film is prepared using a rare earth electrolytic protection process developed by Chaobang Chemical.

[0088] 5 g / L cerium acetate, 15 g / L sodium molybdate, 35 g / L HEDP-2Na complexing agent, 150 g / L anhydrous sodium carbonate, electrolyte pH 12, cathode current density 1 A / dm³ 2Operating at room temperature, using the plated part as the cathode and the titanium plate as the anode, electrolysis for 80 seconds.

[0089] 7. Drying: High-strength steel structural components are dried using conventional drying processes after rare earth electrolytic protection.

[0090] 8. Hydrogen removal: High-strength steel structural components undergo hydrogen removal treatment after drying: plated parts are dehydrogenated at 195℃ for 24 hours.

[0091] Example 3: A process, procedure, and coating structure for trivalent chromium plating of high-strength steel structural components includes pretreatment of the high-strength steel substrate and sequential preparation of a cobalt-titanium alloy coating, a cyanide-free copper plating coating, a bright nickel plating coating, a trivalent chromium plating coating, a rare earth electrolytic protective film, and hydrogen removal on the pretreated high-strength steel substrate from the inside out.

[0092] like Figure 1 As shown, a trivalent chromium plating structure for a high-strength steel structural component includes a high-strength steel substrate 1, and a cobalt-titanium alloy plating layer 2, a cyanide-free copper plating layer 3, a bright nickel plating layer 4, a trivalent chromium plating layer 5, and a rare earth electrolytic protective film 6, which are sequentially prepared from the inside to the outside on the high-strength steel substrate 1.

[0093] 1. Pre-processing: The high-strength steel structural component substrate 1 is subjected to the following process: "alkaline ultrasonic degreasing → water washing → alkaline anodic electrolytic degreasing → water washing → sulfuric acid anodic electrolytic activation → water washing".

[0094] The sulfuric acid anodic electrolytic activation includes the following process parameters: Sulfuric acid 180 g / L, room temperature operation, with the workpiece to be plated as the anode, anolyte current density 1.2 A / dm³ 2 Electrolysis for 50 seconds.

[0095] 2. Cobalt-plated titanium alloy: After pretreatment of high-strength steel structural components, a cobalt-titanium alloy coating 2 is prepared using the cobalt-titanium alloy plating process of the present invention. The coating thickness is 8μm, and the mass fraction of titanium in the cobalt-titanium alloy coating is 2%.

[0096] 1) Preparation of cobalt-plated titanium alloy positioning agent: The cobalt-titanium alloy positioning agent includes 25 g / L of the condensation reaction product of salicylic acid and epichlorohydrin, 100 g / L of sodium saccharin, 250 mL / L of sodium propylene sulfonate with a mass fraction of 35%, 6 mL / L of NORFOX PE-600 acidic ethoxylated alcohol phosphate, and 150 mL / L of ethanol.

[0097] Add 1 / 2 volume of pure water to the reaction vessel to prepare the cobalt-titanium alloy positioning agent. Add ethanol and the condensation reaction product of salicylic acid and epichlorohydrin according to the process formula. Stir evenly. Add sodium saccharin, sodium propylene sulfonate (35% by mass), and acidic ethoxylated alcohol phosphate according to the process formula. Stir until the sodium saccharin dissolves. Then add pure water to the required volume and stir evenly to obtain the cobalt-titanium alloy positioning agent.

[0098] 2) Cobalt-plated titanium alloy: Cobalt sulfate heptahydrate 160 g / L, potassium fluorotitanate 8 g / L, sodium fluoride 2 g / L, sodium sulfate 80 g / L, sodium hydrogen succinate 30 g / L, cobalt-titanium alloy leveling agent 10 mL / L, plating bath pH 3.8, plating bath temperature 35℃, cathode current density 0.8 A / dm³ 2 The cathode moves at a speed of 5 m / min. Cobalt particles are used as the anode. The cobalt particles are loaded into a titanium anode basket and covered with an anode bag. The area ratio of the anode to the cathode is 4:1.

[0099] 3. Cyanide-free copper plating: After high-strength steel structural components are plated with cobalt-titanium alloy, a cyanide-free copper plating layer 3 is prepared using the polymer thiocyanate copper plating process developed by Chaobang Chemical, with a plating thickness of 8μm.

[0100] 1) Preparation of copper plating brightener: By weight, 820 parts of deionized water were added to a reaction vessel, and 80 parts of N,N'-di-n-propylethylenediamine, 15 parts of waterborne polyurethane resin, and 100 parts of GRO-70 polyacrylamide were added under stirring. The mixture was stirred until homogeneous to obtain the brightener.

[0101] 2) Plating: Polymeric cuprous thiocyanate 18 g / L, polymeric sodium thiocyanate 130 g / L, sodium hydroxyethylidene diphosphonate 20 g / L, copper plating brightener 10 mL / L, plating bath pH 12.8, plating bath temperature 40℃, cathode current density 1 A / dm³ 2 The cathode moves at a speed of 4 m / min. Oxygen-free electrolytic copper particles are used as the anode. The copper particles are loaded into a titanium anode basket. The area ratio of the anode to the cathode is 4:1. The anode moves at a speed of 4 m / min.

[0102] 4. Bright nickel plating: After cyanide-free copper plating, the high-strength steel structural components were coated with a bright nickel plating layer 4 using the NINFEA 8002 high-filling bright nickel electroplating process from Chaobang Chemical Co., Ltd. The plating layer thickness was 12μm.

[0103] Nickel sulfate hexahydrate 240 g / L, nickel chloride hexahydrate 45 g / L, boric acid 45 g / L, NINFEA 8002 main brightener 0.8 mL / L, NINFEA SC-263 softener 12 mL / L, NINFEA AS-250 auxiliary agent 3 mL / L, NINFEA NI-35 wetting agent 0.6 mL / L, plating bath pH 4.2, operating temperature 65℃, cathode current density 4 A / dm³ 2 Anode current density 2A / dm 2 The system is circulated and filtered 7 times per hour, with uniform air agitation.

[0104] 5. Trivalent chromium plating: After high-strength steel structural components are plated with bright nickel, a trivalent chromium plating layer 5 is prepared using the trivalent chromium plating process of the present invention, with a plating thickness of 0.8 μm.

[0105] 1) Preparation of rare earth additives: The rare earth additives contain 50 g / L of lanthanum chloride heptahydrate and 50 g / L of praseodymium chloride heptahydrate.

[0106] Based on the volume of the prepared rare earth additive, add 4 / 5 of the pure water to the reaction vessel, and while stirring, add lanthanum chloride heptahydrate and praseodymium chloride heptahydrate according to the formula requirements. Stir until the solids are completely dissolved, then add water to the required volume and stir evenly to obtain the rare earth additive.

[0107] 2) Preparation of trivalent chromium plating leveling agent: The trivalent chromium plating leveling agent contains 60 g / L vanadium oxysulfate and 125 g / L concentrated sulfuric acid. Vanadium oxysulfate can improve the chromium plating leveling ability of trivalent chromium, and sulfuric acid is used to adjust the pH and promote the dissolution of vanadium oxysulfate.

[0108] Calculate the volume of the trivalent chromium plating leveling agent, add 4 / 5 of the pure water to the reaction vessel, slowly add concentrated sulfuric acid according to the formula requirements, then add vanadium oxysulfate under stirring, stir until the vanadium oxysulfate dissolves, add pure water to the required volume, and stir evenly to obtain the trivalent chromium plating leveling agent.

[0109] 3) Preparation of accelerator: The accelerator contains 20 g / L of NORFOX PE-600 acidic ethoxylated alcohol phosphate ester. The accelerator is obtained by dissolving NORFOX PE-600 acidic ethoxylated alcohol phosphate ester in water according to the formulation requirements.

[0110] 4) Trivalent chromium plating: The plating solution contains 90 g / L chromium chloride hexahydrate, 120 g / L potassium chloride, 100 g / L ammonium chloride, 21 g / L ammonium bromide, 45 g / L ammonium formate, 60 g / L boric acid, 10 mL / L rare earth additives, 3 mL / L trivalent chromium plating leveling agent, 2 mL / L accelerator, a pH of 2.5, a plating bath temperature of 28℃, and a cathode current density of 12 A / dm³. 2 Medium air mixing.

[0111] 6. Rare earth electrolysis protection: After high-strength steel structural components are chrome-plated with trivalent chromium, a rare earth electrolytic protective film is prepared using a rare earth electrolytic protection process developed by Chaobang Chemical.

[0112] Cerium acetate 2 g / L, sodium molybdate 8 g / L, HEDP-2Na complexing agent 15 g / L, anhydrous sodium carbonate 130 g / L, electrolyte pH 12, cathode current density 1 A / dm³ 2 Operating at room temperature, using the plated part as the cathode and the titanium plate as the anode, electrolysis for 120 seconds.

[0113] 7. Drying: High-strength steel structural components are dried using conventional drying processes after rare earth electrolytic protection.

[0114] 8. Hydrogen removal: High-strength steel structural components undergo hydrogen removal treatment after drying: plated parts are dehydrogenated at 195℃ for 24 hours.

[0115] Example 4: A process, procedure, and coating structure for trivalent chromium plating of high-strength steel structural components includes pretreatment of the high-strength steel substrate and sequential preparation of a cobalt-titanium alloy coating, a cyanide-free copper plating coating, a bright nickel plating coating, a trivalent chromium plating coating, a rare earth electrolytic protective film, and hydrogen removal on the pretreated high-strength steel substrate from the inside out.

[0116] like Figure 1 As shown, a trivalent chromium plating structure for a high-strength steel structural component includes a high-strength steel substrate 1, and a cobalt-titanium alloy plating layer 2, a cyanide-free copper plating layer 3, a bright nickel plating layer 4, a trivalent chromium plating layer 5, and a rare earth electrolytic protective film 6, which are sequentially prepared from the inside to the outside on the high-strength steel substrate 1.

[0117] 1. Pre-processing: The high-strength steel structural component substrate 1 is subjected to the following process: "alkaline ultrasonic degreasing → water washing → alkaline anodic electrolytic degreasing → water washing → sulfuric acid anodic electrolytic activation → water washing".

[0118] The sulfuric acid anodic electrolytic activation includes the following process parameters: Sulfuric acid 240 g / L, room temperature operation, with the workpiece to be plated as the anode, anolyte current density 0.8 A / dm³ 2 Electrolysis for 45 seconds.

[0119] 2. Cobalt-plated titanium alloy: After pretreatment of high-strength steel structural components, a cobalt-titanium alloy coating 2 is prepared using the cobalt-titanium alloy plating process of the present invention. The coating thickness is 8μm, and the mass fraction of titanium in the cobalt-titanium alloy coating is 2%.

[0120] 1) Preparation of cobalt-plated titanium alloy positioning agent: The cobalt-titanium alloy positioning agent includes 25 g / L of the condensation reaction product of salicylic acid and epichlorohydrin, 100 g / L of sodium saccharin, 250 mL / L of sodium propylene sulfonate with a mass fraction of 35%, 6 mL / L of NORFOX PE-600 acidic ethoxylated alcohol phosphate, and 150 mL / L of ethanol.

[0121] Add 1 / 2 volume of pure water to the reaction vessel to prepare the cobalt-titanium alloy positioning agent. Add ethanol and the condensation reaction product of salicylic acid and epichlorohydrin according to the process formula. Stir evenly. Add sodium saccharin, sodium propylene sulfonate (35% by mass), and acidic ethoxylated alcohol phosphate according to the process formula. Stir until the sodium saccharin dissolves. Then add pure water to the required volume and stir evenly to obtain the cobalt-titanium alloy positioning agent.

[0122] 2) Cobalt-plated titanium alloy: Cobalt sulfate heptahydrate 190 g / L, potassium fluorotitanate 11 g / L, sodium fluoride 7 g / L, sodium sulfate 110 g / L, sodium hydrogen succinate 45 g / L, cobalt-titanium alloy leveling agent 10 mL / L, plating bath pH 4.2, plating bath temperature 25℃, cathode current density 1.2 A / dm³ 2 The cathode moves at a speed of 5 m / min. Cobalt particles are used as the anode. The cobalt particles are loaded into a titanium anode basket and covered with an anode bag. The area ratio of the anode to the cathode is 3:1.

[0123] 3. Cyanide-free copper plating: After high-strength steel structural components are plated with cobalt-titanium alloy, a cyanide-free copper plating layer 3 is prepared using the polymer thiocyanate copper plating process developed by Chaobang Chemical, with a plating thickness of 8μm.

[0124] 1) Preparation of copper plating brightener: By weight, 820 parts of deionized water were added to a reaction vessel, and 80 parts of N,N'-di-n-propylethylenediamine, 15 parts of waterborne polyurethane resin, and 100 parts of GRO-70 polyacrylamide were added under stirring. The mixture was stirred until homogeneous to obtain the brightener.

[0125] 2) Plating: Polymeric cuprous thiocyanate 23 g / L, polymeric sodium thiocyanate 160 g / L, sodium hydroxyethylidene diphosphonate 28 g / L, copper plating brightener 10 mL / L, plating bath pH 12.2, plating bath temperature 33℃, cathode current density 1 A / dm³2 The cathode moves at a speed of 4 m / min. Oxygen-free electrolytic copper particles are used as the anode. The copper particles are loaded into a titanium anode basket. The area ratio of the anode to the cathode is 3.2:1. The anode moves at a speed of 4 m / min.

[0126] 4. Bright nickel plating: After cyanide-free copper plating, the high-strength steel structural components were coated with a bright nickel plating layer 4 using the NINFEA 8002 high-filling bright nickel electroplating process from Chaobang Chemical Co., Ltd. The plating layer thickness was 18μm.

[0127] Nickel sulfate hexahydrate 280 g / L, nickel chloride hexahydrate 65 g / L, boric acid 40 g / L, NINFEA 8002 main brightener 0.8 mL / L, NINFEA SC-263 softener 12 mL / L, NINFEA AS-250 auxiliary agent 3 mL / L, NINFEA NI-35 wetting agent 0.6 mL / L, plating bath pH 4.6, operating temperature 58℃, cathode current density 4 A / dm³ 2 Anode current density 2A / dm 2 The system is circulated and filtered 6 times per hour, with uniform air agitation.

[0128] 5. Trivalent chromium plating: After high-strength steel structural components are plated with bright nickel, a trivalent chromium plating layer 5 is prepared using the trivalent chromium plating process of the present invention, with a plating thickness of 0.8 μm.

[0129] 1) Preparation of rare earth additives: The rare earth additives contain 50 g / L of lanthanum chloride heptahydrate and 50 g / L of praseodymium chloride heptahydrate.

[0130] Based on the volume of the prepared rare earth additive, add 4 / 5 of the pure water to the reaction vessel, and while stirring, add lanthanum chloride heptahydrate and praseodymium chloride heptahydrate according to the formula requirements. Stir until the solids are completely dissolved, then add water to the required volume and stir evenly to obtain the rare earth additive.

[0131] 2) Preparation of trivalent chromium plating leveling agent: The trivalent chromium plating leveling agent contains 60 g / L vanadium oxysulfate and 125 g / L concentrated sulfuric acid. Vanadium oxysulfate can improve the chromium plating leveling ability of trivalent chromium, and sulfuric acid is used to adjust the pH and promote the dissolution of vanadium oxysulfate.

[0132] Calculate the volume of the trivalent chromium plating leveling agent, add 4 / 5 of the pure water to the reaction vessel, slowly add concentrated sulfuric acid according to the formula requirements, then add vanadium oxysulfate under stirring, stir until the vanadium oxysulfate dissolves, add pure water to the required volume, and stir evenly to obtain the trivalent chromium plating leveling agent.

[0133] 3) Preparation of accelerator: The accelerator contains 20 g / L of NORFOX PE-600 acidic ethoxylated alcohol phosphate ester. The accelerator is obtained by dissolving NORFOX PE-600 acidic ethoxylated alcohol phosphate ester in water according to the formulation requirements.

[0134] 4) Trivalent chromium plating: The plating solution contained 120 g / L chromium chloride hexahydrate, 110 g / L potassium chloride, 140 g / L ammonium chloride, 24 g / L ammonium bromide, 48 g / L ammonium formate, 58 g / L boric acid, 10 mL / L rare earth additives, 3 mL / L trivalent chromium plating leveling agent, and 2 mL / L accelerator. The pH of the plating solution was 3.1, the plating bath temperature was 32℃, and the cathode current density was 12 A / dm³. 2 Medium air mixing.

[0135] 6. Rare earth electrolysis protection: After high-strength steel structural components are chrome-plated with trivalent chromium, a rare earth electrolytic protective film is prepared using a rare earth electrolytic protection process developed by Chaobang Chemical.

[0136] Cerium acetate 4 g / L, sodium molybdate 12 g / L, HEDP-2Na complexing agent 32 g / L, anhydrous sodium carbonate 100 g / L, electrolyte pH 12, cathode current density 1 A / dm³ 2 Operating at room temperature, using the plated part as the cathode and the titanium plate as the anode, electrolysis for 80 seconds.

[0137] 7. Drying: High-strength steel structural components are dried using conventional drying processes after rare earth electrolytic protection.

[0138] 8. Hydrogen removal: High-strength steel structural components undergo hydrogen removal treatment after drying: plated parts are dehydrogenated at 195℃ for 24 hours.

[0139] Experimental Example 1: The high-strength steel is designated as 23Co14Ni12Cr3Mo. Hydrogen embrittlement test bars were prepared according to HB 5067.1–2005 "Hydrogen embrittlement test of plating process - Part 1: Mechanical method". Following the process requirements of Example 1, a cobalt-titanium alloy coating, a cyanide-free copper plating, a bright nickel plating, and a trivalent chromium plating were sequentially prepared on the surface of the degreased test bar. Then, hydrogen was removed at 200°C for 24 hours. According to the HB 5067.1–2005 standard, the test bar did not break after being stretched for 200 hours, and the test results met the standard requirements.

[0140] Experimental Example 2: Acetic acid salt spray test was conducted according to GB / T 10125–2021 "Artificial Atmosphere Corrosion Test - Salt Spray Test". The high-strength steel trivalent chromium-plated sample prepared in Example 1 showed no white rust on the surface after 96 hours, meeting the requirements of GB / T 9797–2022 "Metallic and Other Inorganic Coatings - Nickel, Nickel + Chromium, Copper + Nickel and Copper + Nickel + Chromium Electroplating Coatings".

[0141] Experimental Example 3: The high-strength steel trivalent chromium-plated samples prepared in Examples 1, 2, 3 and 4 were tested for adhesion strength using the thermal shock test method according to GB / T 5270–2005 "Review of Test Methods for Adhesion Strength of Electrodeposition and Chemical Deposition of Metallic Coatings on Metal Substrates". The samples were heated to 300°C in a heating furnace and held for 60 minutes. They were then removed and rapidly cooled in water at room temperature. No blistering or peeling of the coating was observed, indicating good adhesion.

[0142] Experimental Example 4: The high-strength steel trivalent chromium-plated samples prepared in Examples 1, 2, 3, and 4 were tested for 500 hours at 40°C and 93% relative humidity according to GB / T 2423.3–2016 "Basic Environmental Testing Procedures for Electrical and Electronic Products - Test Ca: Constant Damp Heat Test Method". The coatings showed no visible changes, which is far higher than the requirement of no coating change after 168 hours of constant damp heat test.

[0143] Experimental Example 5: Preparation of cobalt-titanium alloy plating bath: 180 g / L cobalt sulfate heptahydrate, 10 g / L potassium fluorotitanate, 5 g / L sodium fluoride, 100 g / L sodium sulfate, 40 g / L sodium hydrogen succinate, 10 mL / L leveling agent; pH of the plating bath: 4.1; temperature: 25℃. A 267 mL Hull cell test was conducted at 1.5 A / dm². 2 The current plating was applied for 20 minutes. The mass fraction of titanium in the cobalt-titanium alloy coating was determined using X-ray spectroscopy (HITACHI FT-160S), and the results are listed in Table 1.

[0144] Table 1. Variation of mass fraction of titanium in cobalt-titanium alloy coating with current density Comparative Example 1: Following the process described in Example 1, a cobalt-titanium alloy plating layer, a cyanide-free copper plating layer, and a bright nickel plating layer were sequentially prepared on a high-strength steel structural component. Then, a trivalent chromium plating layer was prepared using the following trivalent chromium plating process.

[0145] The plating solution contains 110 g / L chromium chloride hexahydrate, 110 g / L potassium chloride, 110 g / L ammonium chloride, 21 g / L ammonium bromide, 48 g / L ammonium formate, 55 g / L boric acid, 3 mL / L leveling agent, 2 mL / L trivalent chromium plating accelerator, a plating solution pH of 2.8, a plating bath temperature of 30°C, and a cathode current density of 13 A / dm³. 2 Medium air mixing.

[0146] The difference from Example 1 is that no rare earth additives were added to the plating solution.

[0147] After the high-strength steel structural components are chrome-plated with trivalent chromium, they are subjected to rare earth electrolytic protection, drying, and hydrogen removal in sequence according to the process in Example 1.

[0148] Acetic acid salt spray test was conducted according to GB / T 10125–2021 "Artificial Atmosphere Corrosion Test - Salt Spray Test". Grayish-white corrosion products appeared on the surface of the prepared samples after 60 hours. Comparison of the acetic acid salt spray test results of Example 2 and Comparative Example 1 shows that the addition of rare earth additives to the trivalent chromium plating solution extended the acetic acid salt spray test time by 60%.

[0149] The technical solutions provided by the embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the embodiments of the present invention. The descriptions of the embodiments above are only for helping to understand the principles of the embodiments of the present invention. It should be noted that, for those skilled in the art, based on the principles and concepts of the embodiments of the present invention, several modifications and improvements can be made in specific implementation methods and application scope, and these should all fall within the protection scope of the present invention.

Claims

1. A trivalent chromium plating process for high-strength steel structural components, characterized in that, Including the following process parameters: Chromium chloride hexahydrate 90–130 g / L, potassium chloride 80–120 g / L, ammonium chloride 100–150 g / L, ammonium bromide 18–24 g / L, ammonium formate 45–50 g / L, boric acid 50–60 g / L, rare earth additives 8–12 mL / L, trivalent chromium plating leveling agent 2–4 mL / L, accelerator 1–3 mL / L, plating bath pH 2.5–3.2, plating bath temperature 25–35℃, cathode current density 10–16 A / dm³ 2 Medium air mixing; The rare earth additives contain 30-70 g / L lanthanum chloride heptahydrate and 30-70 g / L praseodymium chloride heptahydrate, which are used to refine the grains of the trivalent chromium plating layer and improve its corrosion resistance. The trivalent chromium plating leveling agent contains 40-80 g / L of vanadium oxysulfate and 100-150 g / L of concentrated sulfuric acid; The accelerator contains 15-25 g / L of NORFOX PE-600 acid ethoxylated alcohol phosphate.

2. The trivalent chromium plating process for high-strength steel structural components as described in claim 1, characterized in that, The rare earth additives are prepared according to the following method: Based on the volume of the prepared rare earth additive, add 4 / 5 of the pure water to the reaction vessel, and while stirring, add lanthanum chloride heptahydrate and praseodymium chloride heptahydrate according to the formula requirements. Stir until the solids are completely dissolved, then add pure water to the required volume and stir evenly to obtain the rare earth additive.

3. The trivalent chromium plating process for high-strength steel structural components as described in claim 1, characterized in that, The trivalent chromium plating leveling agent is prepared according to the following method: Calculate the volume of the prepared trivalent chromium plating leveling agent, add 4 / 5 of the pure water to the reaction vessel, slowly add concentrated sulfuric acid according to the formula requirements, then add vanadium oxysulfate under stirring, stir until the vanadium oxysulfate dissolves, add pure water to the required volume, and stir evenly to obtain the trivalent chromium plating leveling agent.

4. A trivalent chromium plating process for high-strength steel structural components, characterized in that, The process includes the following steps: (1) Pretreatment of high-strength steel structural components, including degreasing and sulfuric acid anodic electrolytic activation; (2) After the high-strength steel structural components are pretreated, a cobalt-titanium alloy coating is prepared by a cobalt-titanium alloy plating process. (3) After high-strength steel structural components are plated with cobalt-titanium alloy, a cyanide-free copper plating layer is prepared using a cyanide-free copper plating process. (4) After cyanide-free copper plating, high-strength steel structural components are prepared with a bright nickel plating process. (5) After high-strength steel structural components are plated with bright nickel, a trivalent chromium plating layer is prepared using the aforementioned trivalent chromium plating process. (6) After trivalent chromium plating, high-strength steel structural components are prepared with rare earth electrolytic protection process to prepare rare earth electrolytic protective film. (7) High-strength steel structural components undergo hydrogen removal treatment after rare earth electrolytic protection; The cobalt-titanium alloy plating process includes the following process parameters: Cobalt sulfate heptahydrate 160–200 g / L, potassium fluorotitanate 8–12 g / L, sodium fluoride 2–8 g / L, sodium sulfate 80–120 g / L, sodium hydrogen succinate 30–50 g / L, cobalt-titanium alloy leveling agent 8–12 mL / L, plating bath pH 3.8–4.4, plating bath temperature 20–35℃, cathode current density 1–2 A / dm³ 2 The cathode moves at a speed of 4-6 m / min. Cobalt particles are used as the anode. The cobalt particles are loaded into a titanium anode basket and covered with an anode bag. The area ratio of the anode to the cathode is (3-6):

1. The cobalt-titanium alloy positioning agent comprises 20-30 g / L of the condensation reaction product of salicylic acid and epichlorohydrin, 80-120 g / L of sodium saccharin, 200-300 mL / L of sodium propylene sulfonate with a mass fraction of 35%, 4-8 mL / L of NORFOX PE-600 acid ethoxylated alcohol phosphate, and 140-160 mL / L of ethanol.

5. The trivalent chromium plating process for high-strength steel structural components as described in claim 4, characterized in that, The aforementioned cyanide-free copper plating process employs a polymeric thiocyanate copper plating process: The process includes 18-24 g / L of polymerized cuprous thiocyanate, 130-170 g / L of polymerized sodium thiocyanate, 20-30 g / L of sodium hydroxyethylidene diphosphonate, 8-12 mL / L of copper plating brightener, a plating bath pH of 12-13, a plating bath temperature of 30-40℃, and a cathode current density of 0.5-1.5 A / dm³. 2 The cathode moves at a speed of 3-5 m / min. Oxygen-free electrolytic copper particles are used as the anode. The copper particles are loaded into a titanium anode basket. The area ratio of the anode to the cathode is (3-4):

1. The anode moves at a speed of 3-5 m / min.

6. A trivalent chromium plating structure for high-strength steel structural components, characterized in that: It includes a high-strength steel substrate, and a cobalt-titanium alloy coating, a cyanide-free copper plating layer, a bright nickel plating layer, a trivalent chromium plating layer, and a rare earth electrolytic protective film sequentially prepared from the inside to the outside on the high-strength steel substrate.

7. The trivalent chromium plating structure for high-strength steel structural components as described in claim 6, characterized in that: The thickness of the cobalt-titanium alloy coating is 6–12 μm.

8. The trivalent chromium plating structure of high-strength steel structural components as described in claim 6 or 7, characterized in that: The mass fraction of titanium in the cobalt-titanium alloy coating is 0.5% to 3%, and the titanium is used to block the diffusion of hydrogen atoms toward the high-strength steel substrate.

9. The trivalent chromium plating structure for high-strength steel structural components as described in claim 6, characterized in that: The thickness of the cyanide-free copper plating layer is 5-10 μm, and the thickness of the bright nickel plating layer is 6-20 μm. The bright nickel plating layer provides electrochemical protection for the cyanide-free copper plating layer.

10. The trivalent chromium plating structure for high-strength steel structural components as described in claim 6, characterized in that: The thickness of the trivalent chromium plating layer is 0.4–1.2 μm.

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