26 results about "Cathode current density" patented technology

The invention discloses an electrolyte for preparing refined antimony by electrolytically separating a lead-antimony alloy and application of the electrolyte, and belongs to the technical field of electrochemical metallurgy. According to the method, a mixed acid solution prepared from antimony sulfate, ammonium fluoride and oxalic acid is adopted as an electrolyte, a stainless steel plate, a copper plate or a pure antimony plate is adopted as a cathode, a lead-antimony alloy plate is adopted as an anode, electrolysis is conducted for 24-120 h under the conditions that the density of direct current and cathode current is 200-400 A / m < 2 >, the heteropolar distance is 40-100 mm, and the electrolysis temperature is room temperature (20-30 DEG C), and the cathode refined antimony is obtained. The electrolysis process can be one-stage electrolysis or multi-stage electrolysis. The electrolysis method has the advantages of being clean, environmentally friendly, low in energy consumption, low in cost, low in electrolytic bath voltage, high in current efficiency, low in direct current consumption and the like, and the cathode antimony product which is high in purity and compact and excellent in surface appearance can be rapidly prepared from the lead-antimony alloy through electrolysis.

The application discloses a kind of based on the coupling of electrochemical parameter gap corrosion evaluation method and device, it is related to electrochemical corrosion evaluation technical field.Gap corrosion evaluation method includes the following steps: based on gap structure establishes oxygen concentration cell, determines anode, cathode and its surface area;In the oxygen-poor medium environment, the anodic polarization curve of target material is measured, the cathodic polarization curve of target material is measured in the oxygen-rich medium environment, obtains anode current density-potential relationship and cathode current density-potential relationship;According to the electrochemical balance formula that total cathode current is equal to total anode current, the coupling potential of oxygen concentration cell is calculated, and further the gap corrosion current density corresponding to coupling potential is obtained, and the gap corrosion rate is calculated according to gap corrosion current density.The gap corrosion evaluation method provided by the application is suitable for the rapid prediction of initial stage of gap corrosion, with the characteristics of convenient, high repeatability, the result is more accurate.

This invention discloses a process and coating structure for rare earth modified trivalent chromium pearl chromium plating on zinc alloys. The process includes sequentially preparing a cyanide-free copper plating layer, a cyanide-free copper-zinc alloy plating layer, a high-corrosion-resistant nickel-phosphorus alloy plating layer, a bright nickel-cobalt alloy plating layer, a pearl nickel plating layer, a rare earth modified trivalent chromium pearl chromium plating layer, and an anti-discoloration protective film on a zinc alloy substrate. The rare earth modified trivalent chromium pearl chromium plating process is as follows: chromium chloride hexahydrate 90-130 g / L, potassium chloride 90-160 g / L, ammonium chloride 90-160 g / L, ammonium bromide 18-28 g / L, ammonium formate 40-60 g / L, boric acid 45-65 g / L, rare earth additives 8-12 mL / L, leveling agent 2-4 mL / L, accelerator 1-3 mL / L, plating bath pH 2.5-3.2, plating bath temperature 25-35℃, and cathode current density 8-16 A / dm². The rare earth additives have a synergistic effect on improving the performance of trivalent chromium plating solution. No rust was observed on the surface of the plated parts after undergoing a neutral salt spray test for 132 hours according to GB / T 10125–2021 standard.

The invention relates to the technical field of copper electrolysis, in particular to a copper electrolytic refining method and application thereof. The copper electrolytic refining method comprises the following steps: placing an anode and a cathode in an electrolytic bath containing electrolyte for electrolysis; the distance between the electrodes is 85 to 95 mm; the electrolyte is prepared from the following components: 38 to 42 g / L of CuSO4, 185 to 205 g / L of H2SO4, 1 to 2 g / L of Fe, 6 to 8 g / L of As and 13 to 16 g / L of Ni; the electrolyte further comprises bone glue, thiourea and a polyethylene glycol-amino silane copolymer. According to the invention, by reducing the inter-electrode distance, the cathode current density is reduced, and the cell voltage and the power consumption are reduced; by optimizing an electrolyte system, the ion migration rate is increased, it can be ensured that copper ions rapidly and uniformly reach the surface of an electrode for a deposition reaction, and the electrolysis efficiency is remarkably improved; by adopting the ternary additive system, the crystal morphology of the cathode copper can be improved, and the purity of the cathode copper can be improved.

A method for preparing nickel powder through electrolysis of nickel sulfate waste liquid in one step comprises the steps that the nickel sulfate waste liquid is diluted to a certain concentration by controlling the reduction degree of Ni < 2 + > under different cathode conditions, and different nickel electrolysis products are selectively prepared in the diluent; ti plated TaO2 / I rO2 alloy is used as an anode, a Ti sheet is used as a cathode, electrolysis is carried out under the conditions that the current density is 30-2000A / m < 2 >, the electrolyte temperature is 20-60 DEG C and the nickel ion concentration is 0.025-1.0 mo l / L, and nickel powder is obtained through electrodeposition on the cathode after electrolysis is finished; a circulating pump is used for recycling waste liquid; the electrolytic nickel powder prepared through the method is simple in required equipment, short in technological process, mild in condition, low in production cost, high in efficiency, environmentally friendly, suitable for one-step preparation of the nickel powder through the high-impurity nickel sulfate waste liquid and suitable for one-step preparation of the electrolytic nickel powder through the pure nickel sulfate solution. The method is especially suitable for environmental protection enterprises of nickel-containing waste liquid.

The invention discloses a process for plating high-strength structural steel with a low-hydrogen brittleness zinc-nickel alloy and a plating structure. The process comprises the steps that cobalt-titanium alloy plating, zinc-nickel alloy plating and hexavalent chromium passivation are sequentially carried out on a high-strength structural steel matrix. The cobalt-titanium alloy plating process comprises the following components and parameters: 160-200 g / L of cobalt sulfate heptahydrate, 8-12 g / L of potassium fluotitanate, 2-8 g / L of sodium fluoride, 80-120 g / L of sodium sulfate, 30-50 g / L of sodium hydrogen succinate, 8-12 mL / L of a walking agent and 1-3 mL / L of a wetting agent, the pH value of a plating solution is 3.8-4.4, the temperature of a plating tank is 20-35 DEG C, the cathode current density is 1-2 A / dm < 2 >, and the cathode movement is 4-6 m / min. The hydrogen brittleness test is carried out according to HB 5067.1-2005 Part 1 of Hydrogen brittleness Test of Plating Process: Mechanical Method, and the test result meets the standard requirement. According to the technical scheme, the problem that high-strength structural steel galvanized nickel alloy is prone to hydrogen brittleness is solved.

The present disclosure relates to the technical field of electrode materials and provides a titanium-based platinum-nickel electrode material, a preparation method, and an application thereof. The method includes: performing a first anodic oxidation and a second anodic oxidation sequentially on a titanium sheet in an ammonium fluoride solution to obtain an oxidized titanium sheet; performing calcination on the oxidized titanium sheet to obtain a titanium sheet containing a titanium dioxide layer; and performing electrodeposition on the titanium sheet containing the titanium dioxide layer in a platinum-based electrolyte to obtain the titanium-based platinum-nickel electrode material. The prepared titanium-based platinum-nickel electrode material effectively reduces the usage amount of Pt-based precious metals and can maintain high activity and stability to generate hydrogen peroxide on-line under the neutral condition; its cathode current density efficiency reaches 76.40%, the anode current density efficiency reaches 70.23%, and the bilayer capacitance value is 1.33 mF·cm−2, which is 4.2 times the bilayer capacitance value of the titanium-based platinum-nickel electrode material obtained without anodic oxidation, and has a very good industrial application prospect.

The invention relates to the technical field of electrochemical surface treatment, and discloses a platinum electroplating process for corrosion prevention and scale inhibition of an inner cavity of a converter valve aluminum radiator, which comprises the following steps: degreasing and activating the surface of an aluminum alloy radiator with a runner, and constructing a microscopic rough surface; an auxiliary counter electrode wrapped with a polypropylene net sleeve is arranged in the center of the runner; injecting an electrolyte consisting of chloroplatinic acid, phosphate and an interfacial agent into the runner; and adjusting the pressure of a circulating pump, so that the flow velocity of the electrolyte is periodically switched between a high speed and a low speed, and the cathode current density is controlled to be synchronously adjusted and increased in a flow velocity rising edge interval. And a compact platinum layer with uniform thickness and stable adhesion is formed on the inner surface of the radiator.

The invention relates to non-ferrous metal industry and can be used for refining aluminium alloys from metallic impurities. The device comprises no less than one porous removable diaphragm, permeable to bath and impermeable to molten aluminium, filled with bath, wherein cathode is vertically mounted and immersed in molten aluminium with metallic impurities, placed in a vessel with an anode current lead. The method involves placing a melt of contaminated aluminium and a bath of salts of alkali or alkaline-earth metals and aluminium salt into an electrolytic refining device and performing electrolytic refining at a cathodic current density from 0.5 to 21 A / cm2 a temperature ranging from 780 °C to 920 °C. Technical effect: increased capacity, with the ability to adjust the bath composition.

The invention discloses a high-strength steel cobalt-titanium alloy plating solution, an electroplating process and a combined plating layer preparation method. The cobalt-titanium alloy plating solution and the electroplating process comprise the following components and parameters: 160-200 g / L of cobalt sulfate heptahydrate, 8-12 g / L of potassium fluotitanate, 2-8 g / L of sodium fluoride, 80-120 g / L of sodium sulfate, 30-50 g / L of sodium hydrogen succinate and 8-12 mL / L of a displacement agent, the pH value of the plating solution is 3.8-4.4, the temperature of a plating tank is 20-35 DEG C, the cathode current density is 1-2 A / dm < 2 >, and the cathode movement is 4-6 m / min. The preparation method of the coating comprises the step of sequentially preparing the cobalt-titanium alloy coating, the potassium chloride zinc-iron alloy layer, the trivalent chromium passivation layer and the graphene modified sealing layer on the high-strength steel substrate. The hydrogen brittleness test is carried out according to HB 5067.1-2005 Part 1 of Hydrogen brittleness Test of Plating Process: Mechanical Method, and the test result meets the standard requirement. The coating preparation process has a good market prospect.

The invention discloses a process method for plating nickel-cobalt alloy on high-strength steel and a plating layer structure. The process method comprises the steps that cobalt-titanium alloy plating, nickel-copper alloy plating, nickel-cobalt alloy plating and rare earth electrolysis protection are sequentially carried out on a high-strength steel substrate. The cobalt-titanium alloy plating process comprises the following components and parameters: 160-200 g / L of cobalt sulfate heptahydrate, 8-12 g / L of potassium fluotitanate, 2-8 g / L of sodium fluoride, 80-120 g / L of sodium sulfate, 30-50 g / L of sodium hydrogen succinate and 8-12 mL / L of a displacement agent, the pH value of a plating solution is 3.8-4.4, the temperature of a plating tank is 20-35 DEG C, the cathode current density is 1-2 A / dm < 2 >, and the cathode movement is 4-6 m / min. The hydrogen brittleness test is carried out according to HB 5067.1-2005 Part 1 of Hydrogen brittleness Test of Plating Process: Mechanical Method, and the test result meets the standard requirement. The plating layer of the process is excellent in performance and has a good market prospect.

The invention discloses a low-hydrogen embrittlement potassium chloride cadmium plating process for high-strength steel and a plating layer structure. The low-hydrogen embrittlement potassium chloride cadmium plating process comprises the steps that cobalt-titanium alloy plating, potassium chloride cadmium plating and hexavalent chromium passivation are sequentially carried out on a high-strength steel substrate. The cobalt-titanium alloy plating process parameters comprise 160-200 g / L of cobalt sulfate heptahydrate, 8-12 g / L of potassium fluotitanate, 2-8 g / L of sodium fluoride, 80-120 g / L of sodium sulfate, 30-50 g / L of sodium hydrogen succinate and 8-12 mL / L of a displacement agent, the pH value of a plating solution is 3.8-4.4, the temperature of a plating tank is 20-35 DEG C, the cathode current density is 1-2 A / dm < 2 >, and the cathode movement is 4-6 m / min. The hydrogen brittleness test is carried out according to HB 5067.1-2005 Part 1 of Hydrogen brittleness Test of Plating Process: Mechanical Method, and the test result meets the standard requirement. The process is stable in plating solution, excellent in plating performance and good in market prospect.

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.

The application discloses a trivalent chromium plating process, which comprises the following process parameters: chromium chloride hexahydrate 80-140 g / L, potassium chloride 90-160 g / L, ammonium chloride 90-160 g / L, ammonium bromide 16-30 g / L, ammonium formate 40-60 g / L, boric acid 45-65 g / L, rare earth additive 8-12 mL / L, walking agent 2-4 mL / L, accelerator 1-3 mL / L, plating solution pH value 2.5-3.2, plating bath temperature 25-35 DEG C, cathode current density 10-18 A / dm 2 2, inert anode is adopted, and moderate air stirring is adopted. The rare earth additive comprises lanthanum chloride heptahydrate 40-140 g / L and praseodymium chloride heptahydrate 0-130 g / L. The steel base is subjected to cyanide-free copper plating + bright nickel plating + trivalent chromium plating + rare earth electrolytic protection, neutral salt spray test is carried out according to GB / T 10125-2021 'Salt Spray Test of Artificial Atmosphere Corrosion Test', and the prepared sample surface is free of corrosion product generation. The technical scheme obviously improves the corrosion resistance of the trivalent chromium plating layer, and has a good market prospect.

The application relates to the technical field of titanium alloy, in particular to a special electroplating base nickel process for titanium alloy. The process comprises the following steps: firstly, removing oil from a titanium alloy base body through alkaline electrolysis; secondly, activating the titanium alloy base body in an activation solution compounded by hydrochloric acid and ammonium hydrogen fluoride at 20-25 DEG C for 20-45s, and then transferring the titanium alloy base body to an electroplating tank after washing; thirdly, electroplating in a cyanide-free base nickel electroplating solution containing nickel sulfate, nickel chloride, boric acid and modified sodium sulfate, controlling the pH value to be 3.5-4.5, the temperature to be 50-65 DEG C, the cathode current density to be 2-5 A / dm 2 , and adopting two-stage current density power supply. The modified sodium sulfate is prepared through freezing-out crystallization and heterogeneous nucleation technology, takes aluminum nitride as a nucleation core, adds sodium silicate, sodium dihydrogen phosphate and sodium tetraborate decahydrate for regulation and control, and finally obtains high-purity and uniform-particle-size crystals. The process is environment-friendly and cyanide-free, the plating layer has strong adhesion, high compactness, few defects and good batch consistency.

The application discloses a potassium chloride zinc-iron alloy plating process for magnesium alloy parts, and sequentially prepares a chemical zinc deposition layer, a cyanide-free pre-copper plating layer, a pyrophosphate copper plating layer, a zinc-iron alloy plating layer, a passivation film and a graphene modified sealing layer on the magnesium alloy substrate from inside to outside. The potassium chloride zinc-iron alloy plating process is as follows: zinc chloride 50-70 g / L, ferrous chloride tetrahydrate 2-12 g / L, potassium chloride 180-220 g / L, boric acid 25-35 g / L, complexing agent 8-40 g / L, brightener 0.1-0.2 mL / L, auxiliary agent 20-30 mL / L, plating solution pH value 4.5-5.6, plating bath temperature 15-30 DEG C, cathode current density 1-3 A / dm 2 , cathode moving speed 3-5 m / min. The magnesium alloy zinc-iron alloy plated sample prepared by the application and sealed by trivalent chromium blue-white passivation and graphene modified sealing agent has no white rust on the surface after neutral salt spray test for 480 h according to the GB / T 10125-2021 standard, and the plating layer has excellent corrosion resistance.

The invention discloses a technological method for plating zinc-nickel alloy on a magnesium alloy part and a plating layer structure. The technological method comprises the step that a micro-arc oxidation layer, a chemical nickel plating layer, a cobalt-titanium alloy plating layer, a zinc-nickel alloy plating layer, a trivalent chromium passivation film and a graphene modified sealing layer are sequentially prepared on a magnesium alloy base body from inside to outside. The cobalt-titanium alloy plating process comprises the following process components and parameters: 200-240 g / L of cobalt sulfate heptahydrate, 8-12 g / L of potassium fluotitanate, 2-8 g / L of sodium fluoride, 80-120 g / L of sodium sulfate, 30-50 g / L of sodium hydrogen succinate and 8-12 mL / L of a walking agent, the pH value of a plating solution is 3.8-4.4, the temperature of a plating tank is 45-55 DEG C, the cathode current density is 2.5-3.5 A / dm < 2 >, the cathode movement is 4-6 m / min, and medium air is added for stirring. The surface of a prepared sample piece is free of white rust after being subjected to a neutral salt spray test for 1200 h according to the GB / T 10125-2021 standard, and a plating layer has excellent corrosion resistance.

This invention discloses a cyanide-free cadmium-iron alloy plating process for NdFeB substrates suitable for the aerospace field. The process involves sequentially preparing a sulfate zinc plating layer, a cyanide-free copper-zinc alloy plating layer, a cyanide-free cadmium-iron alloy plating layer, and a passivation layer on a NdFeB substrate from the inside out. The cyanide-free cadmium-iron alloy plating process is as follows: 25-35 g / L cadmium chloride, 4-6 g / L ferrous chloride tetrahydrate, 100-140 g / L potassium chloride, 100-140 g / L complexing agent, 1.5-2.5 mL / L leveling agent, 1.5-2.5 mL / L brightener, 25-30 mL / L auxiliary agent, 25-35 g / L stabilizer, pH of the plating bath 6-8, plating bath temperature 20-35℃, and cathode current density 0.5-1.5 A / dm³. 2 The cathode moved at a speed of 2–4 m / min. The prepared NdFeB-plated cadmium-iron alloy color passivated samples were subjected to an acetic acid spray test for 360 h according to GB / T 10125–2021 standard. No white rust was found on the surface, and the coating exhibited excellent corrosion resistance.

The invention belongs to the technical field of environmental functional materials and electrochemical water treatment, and discloses a preparation method of a composite electrode, the composite electrode is prepared by using biochar derived from waste sludge and electro-polymerized polypyrrole as functional coatings through slurry coating and constant voltage electro-deposition processes; in addition, the invention further provides a composite electrode and a regeneration method, aiming at the regeneration requirement of the electrode after the electrode is saturated after adsorbing organic pollutants, the saturated electrode is placed in an alkaline regeneration solution to serve as a cathode, and the operation of three stages of pulse cleaning, enhanced oxidation and final cleaning is executed in sequence; by applying different cathode current densities, combining a'power-on-open circuit 'pulse sequence and injecting peroxy-monosulfate on line, the oxidative damage to the polypyrrole active layer is relieved while pollutants are degraded and adsorbed. The sludge waste can be recycled, the electrode preparation cost is low, the adsorption performance is excellent, the regeneration method is controllable in operation, and the service life of the electrode is long.

The application belongs to the technical field of traveling wave tubes, and particularly provides a screening method and equipment for a traveling wave tube electron gun cathode, which comprises the following steps: placing a traveling wave tube after assembly in a vacuum chamber; supplying power to the electron gun of the traveling wave tube by a power supply, and adjusting the power supply to gradually increase the actual working voltage of the cathode; measuring and obtaining the cathode current value of the electron gun, and obtaining the cathode current density by using the cathode current value of the electron gun and the cathode emission area; establishing the corresponding relationship between the actual working voltage and the cathode current density, and calculating the change rate of the cathode current density; when the change rate of the cathode current density is greater than a set value, recording the actual working voltage U1 at this time; calculating the difference ΔU between the actual working voltage U1 and a set working voltage U2; and when ΔU is greater than ΔU a , determining that the electron emission performance of the electron gun cathode in the tested traveling wave tube meets the set requirements. The application is convenient for simulating an electron gun with cathode electron emission performance meeting the requirements by using a smaller voltage.

The invention discloses a potassium chloride cadmium plating process and a plating layer structure of an alloy steel forging part. The potassium chloride cadmium plating process comprises the steps of sequentially carrying out potassium chloride impact cadmium plating, potassium chloride cadmium plating, hydrogen removal and hexavalent chromium passivation on an alloy steel matrix. According to the potassium chloride impact cadmium plating process, 15 g / L to 20 g / L of cadmium chloride, 140 g / L to 160 g / L of potassium chloride, 60 g / L to 90 g / L of a PULIZIER NCC-617 AC coordination agent, 25 mL / L to 30 mL / L of a PULIZIER NCC-617 Base adjuvant, 1.5 mL / L to 2.5 mL / L of a PULIZIER NCC-617 Bri brightener, 5 mL / L to 10 mL / L of a PULIZIER NCC-617 HCD high-area brightener and 2 mL / L to 4 mL / L of a pinhole inhibitor are included, the plating bath temperature is 20 DEG C to 35 DEG C, the pH value of a plating solution is 7 to 9, the cathode current density is 4 A / dm < 2 > to 5 A / The prepared potassium chloride cadmium-plated colorful passivated plating layer structure is free of white rust after being subjected to a neutral salt spray test for 1000 hours. The method effectively solves the problem that the potassium chloride cadmium plating layer of the alloy steel forging part is prone to black spots.

This invention discloses a rare earth modified trivalent chromium plating process and coating structure for magnesium alloys. The process includes sequentially preparing a chemical zinc plating layer, a cyanide-free copper plating layer, a cyanide-free copper-tin alloy plating layer, a bright nickel-copper alloy plating layer, a bright nickel-cobalt alloy plating layer, a rare earth modified trivalent chromium plating layer, and an anti-discoloration protective film on a magnesium alloy substrate. The rare earth-modified trivalent chromium plating process is as follows: 80-140 g / L chromium chloride hexahydrate, 90-160 g / L potassium chloride, 90-160 g / L ammonium chloride, 16-30 g / L ammonium bromide, 40-60 g / L ammonium formate, 45-65 g / L boric acid, 8-12 mL / L rare earth additives, 2-4 mL / L leveling agent, 1-3 mL / L accelerator, pH of the plating solution 2.5-3.2, plating tank temperature 25-35℃, cathode current density 8-16 A / dm², using an inert graphite rod as the anode, and moderate air agitation. The rare earth additives have a synergistic effect on improving the performance of the trivalent chromium plating solution. The plated parts undergo a neutral salt spray test for 140 hours according to GB / T 10125–2021, and no surface corrosion is observed.

The invention discloses a neodymium-iron-boron zinc plating method for maintaining shearing force performance based on high and low temperature circulation. The neodymium-iron-boron zinc plating method comprises the following steps: carrying out electroplating pretreatment on a neodymium-iron-boron magnet; carrying out first-layer zinc plating on the pretreated magnet, wherein the first-layer zinc plating is carried out in a sulfate-containing zinc plating solution; carrying out second-layer zinc plating on the magnet subjected to first-layer zinc plating, wherein the second-layer zinc plating is carried out in a potassium salt-containing zinc plating solution; carrying out electroplating post-treatment on the magnet after the second layer of zinc plating is completed; the cathode current density adopted by the first layer of galvanization is greater than that adopted by the second layer of galvanization. The problems that an existing neodymium-iron-boron magnet is insufficient in shearing force in an extreme temperature environment, and potential safety hazards are likely to be caused are solved, the second-layer current density reducing technology releases coating stress, the high-low-temperature cyclic shearing force of the magnet is improved, meanwhile, the salt mist performance of the magnet is further improved, and the service life of the magnet is prolonged. And the sintered neodymium-iron-boron magnet and the galvanized magnet have high corrosion resistance at the same time.

A complexing agent for zinc-iron alloy electroplating, including component A selected from the group consisting of sodium gluconate, sodium glucoheptonate, potassium sodium tartrate, sodium citrate and a combination thereof, component B being sodium sulfosalicylate. An electroplating solution is provided, including 50-70 g / L of zinc chloride, 2-12 g / L of ferrous chloride tetrahydrate, 160-240 g / L of potassium chloride, 25-35 g / L of boric acid, 6-55 g / L of the complexing agent, 0.1-0.2 mL / L of a brightener and 20-30 mL / L of an electroplating additive, with a pH of 4.5-5.6. During the electroplating process, a temperature of a plating bath is controlled at 15-30° C., a cathode current density is 1-3 A / dm2 and a swept rate of cathode is 3-5 m / min.

The application discloses a rare earth modified trivalent chromium plating method for magnesium alloy after micro-arc oxidation and a plated layer structure, which comprises, from inside to outside on a magnesium alloy substrate, a micro-arc oxidation layer, a high-phosphorus chemical nickel plating layer, a bright nickel-cobalt alloy plating layer, a rare earth modified trivalent chromium plating layer and a rare earth electrolytic protective film. The rare earth modified trivalent chromium plating process comprises the following steps: 90-130 g / L of chromium chloride hexahydrate, 90-160 g / L of potassium chloride, 90-160 g / L of ammonium chloride, 18-28 g / L of ammonium bromide, 40-60 g / L of ammonium formate, 45-65 g / L of boric acid, 8-12 mL / L of a rare earth additive, 2-4 mL / L of a walking agent, 1-3 mL / L of a promoter, a plating solution pH value of 2.5-3.2, a plating bath temperature of 25-35 DEG C, a cathode current density of 8-16 A / dm2, an inert graphite rod as an anode and moderate-strength air agitation. The rare earth additive has a synergistic effect on improving the performance of the trivalent chromium plating solution. The plated part is subjected to a neutral salt spray test according to the GB / T 10125-2021 standard for 136 h, and the surface is free of rust.