Preparation method of environment-friendly electroplating anode for long and thin pipe with large length-diameter ratio

Abstract

The preparation method of the environment-friendly electroplating anode for the long and thin pipe with the large length-diameter ratio is characterized by comprising the following steps that S1, a niobium rod is machined to form a niobium wire; s2, carrying out physical and chemical treatment on the niobium wire; and S3, the treated niobium wire is subjected to metal coating. The electroplating anode produced by the method has the characteristics of high tensile strength, rigidity in the length direction, uniform outer diameter size, good conductivity, good universality, long service life and environmental protection.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electroplating processing, in particular to a preparation method of an environmentally-friendly electroplating anode for a large-length-diameter-ratio slender tube. BACKGROUND

[0002] The inner bore surface of the slender tube is subjected to high-temperature and high-pressure gas ablation and high-speed wear, and the inner bore surface needs to be subjected to surface strengthening treatment to improve the service life. The conventional method adopts hexavalent chromium plating process, and the hexavalent chromium plating anode is prepared by adopting a steel wire lead or lead / tin alloy electroplating process. However, there are the following problems: 1. The hexavalent chromium plating process and the lead or lead / tin alloy electroplating process both involve a kind of toxic heavy metal, hexavalent chromium, which causes environmental pollution; 2. The service life of the anode is short; and 3. The single purpose is hexavalent chromium plating. In recent years, environmentally-friendly electroplating processes such as trivalent chromium plating, cobalt / nickel alloy, and nickel / tungsten alloy are gradually or partially replacing the traditional hexavalent chromium plating process. The steel wire lead or lead / tin alloy anode used in the hexavalent chromium plating process cannot meet the requirements of the electrochemical properties of the anode for the trivalent chromium plating, cobalt / nickel alloy, and nickel / tungsten alloy processes, and the toxic heavy metal lead cannot meet the environmental protection requirements. The requirements of the electroplating anode for the inner bore of the slender tube are as follows: 1. high tensile strength; 2. large length-diameter ratio reaching 100:1 and rigidity; 3. uniform outer diameter size; 4. good electrical conductivity; and 5. electrochemical properties of the anode surface. Although the metal titanium coated with an iridium oxide coating anode meets the requirements of the electrochemical properties of the anode for the trivalent chromium plating, cobalt / nickel alloy, and nickel / tungsten alloy processes, the poor electrical conductivity of the metal titanium with a resistivity of 42 us / cm leads to the attenuation of the longitudinal current of the anode, resulting in a large size taper difference of the electroplated inner bore of the slender tube, which cannot meet the requirements of the electroplating anode for the inner bore of the slender tube for the positive and negative reversal electroplating process. SUMMARY

[0003] The present application aims at the above technical problems, and provides a preparation method of an environmentally-friendly electroplating anode for a large-length-diameter-ratio slender tube, which is prepared according to the following steps:

[0004] S1: processing a niobium rod to form a niobium wire;

[0005] S2: physically and chemically treating the niobium wire;

[0006] S3: metal film plating on the treated niobium wire.

[0007] As an optional solution of the present application, the niobium rod in step S1 is processed and treated by a multi-stage cold-drawing hardening method to form the niobium wire. The niobium wire with a tensile strength of 800 MPa is formed by the method.

[0008] As an optional solution of the present application, the physical treatment in step S2 comprises shot blasting and mechanical straightening.

[0009] As an optional solution of the present application, the chemical treatment in step S2 comprises the steps of degreasing, pickling and activation in sequence.

[0010] As a preferred solution of the present application, the chemical treatment in step S2 is performed in sequence by using the following steps:

[0011] Degreasing of the niobium wire is performed by using sodium hydroxide; the sodium hydroxide is 70-100 g / L, and the temperature is 70-80 DEG C.

[0012] Pickling of the niobium wire is performed by using hydrochloric acid; the hydrochloric acid is 100-150 ml / L.

[0013] Surface activation of the niobium wire is performed by using sulfuric acid and sodium fluoride; the sulfuric acid is 40-50 ml / L, and the sodium fluoride is 8-12 g / L.

[0014] As an optional solution of the present application, the metal platinum is plated on the surface of the niobium wire in step S3.

[0015] As a preferred solution of the present application, 3-4 um metal platinum is plated on the surface of the niobium wire in step S3.

[0016] The present application provides an environmentally-friendly electroplating anode assembly for a large-length-diameter-ratio elongated tube, which comprises an electroplating anode and a stop plug, the stop plug is assembled on one end of the electroplating anode through screw threads, a limiting block is arranged on a section of the electroplating anode, the limiting block is formed by upsetting treatment on the end of the electroplating anode, and the electroplating anode is prepared by using any one of the preparation methods of the electroplating anode in claims 1-7.

[0017] As an optional solution of the present application, the electroplating anode adopts external machining screw threads, and the stop plug adopts internal machining screw threads.

[0018] As a preferred solution of the present application, the exposed part of the anode after the stop plug is screwed in is subjected to mechanical upsetting treatment to form the limiting block. The electroplating anode assembly can withstand large stop pulling force without loosening and falling off.

[0019] The present application has the following beneficial effects:

[0020] The whole process of preparing the anode of the present application does not involve toxic heavy metal lead, which has environmental protection significance and the following performance characteristics:

[0021] 1. High tensile strength (800 MPa). 2. Length direction rigidity. 3. Uniform outer diameter size (tolerance <0.02 mm). 4. Good electrical conductivity (niobium resistivity 12.5 uΩ / cm). 5. Meet the anode electrochemical property requirements of hexavalent chromium, trivalent chromium, cobalt / nickel alloy, nickel / tungsten alloy electroplating process, have positive / negative reversing electroplating current function, suitable for hexavalent chromium, trivalent chromium, cobalt / nickel alloy, nickel / tungsten alloy and other electroplating processes, and have a general type. 6. Long service life of more than 1.5 years, when used for hexavalent chromium plating, the service life is increased by >5 times compared with steel wire electroplating lead or lead / tin alloy anode. 7. The anode preparation engineering does not involve heavy metal lead, and has environmental protection characteristics. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is a processing schematic diagram of an environmental protection type electroplating anode assembly of a large length-diameter ratio elongated pipe.

[0023] Among them: 1-electroplating anode; 2-stop plug; 3-limiting block. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0025] Embodiment 1

[0026] The present application provides a preparation method of an environmental protection type electroplating anode of a large length-diameter ratio elongated pipe:

[0027] 1. The niobium rod (purity >99.5%) is processed to the required size by multi-stage cold drawing hardening treatment, and the tensile strength is 800 MPa;

[0028] 2. Surface 200 mesh, pressure 0.4 MPa shot blasting texturing treatment, remove surface oxides, texturing surface enhances plating layer adhesion;

[0029] 3. Straightening treatment: mechanical straightening;

[0030] 4. Oil removal: sodium hydroxide 70 g / L, temperature: 75℃; Time: 20 min, mode: flow immersion type;

[0031] 5. Pickling: hydrochloric acid 100 ml / L; Temperature: 15℃, Time: 10 min, mode: flow immersion type;

[0032] 6. Activation: sulfuric acid 40 ml / L sodium fluoride 8 g / L; Temperature: 15℃, Time: 5 min, mode: flow immersion type;

[0033] 7. Surface plating thickness 3um metal platinum; dinitrosoplatinum diamine 5 grams / liter, ammonium citrate 3 grams / liter, sodium tartrate 5 grams / liter, sulfamic acid 20 grams / liter, ammonium sulfamate 5 grams / liter, PH value: 0.8 (ammonia water adjustment), temperature: 40℃, cathode current density 0.5 ampere / square decimeter, anode: metal platinum;

[0034] The application discloses a kind of preparation method of elongated tube inner bore environment-friendly electroplating anode, and Nb bar is made into Nb wire by multistage cold-drawing hardening treatment, and electroplating anode is prepared by shot blasting, mechanical straightening, oil removal, pickling, activation and surface plating thickness metal platinum process.The whole process of anode preparation does not involve toxic heavy metal lead, and has environmental protection significance.

[0035] Example 2

[0036] A preparation method of environment-friendly electroplating anode assembly of large-length-diameter ratio elongated tube

[0037] 1. Nb bar (purity > 99.5%) is processed to the required size by multistage cold-drawing hardening treatment, and the tensile strength is 800 MPa.

[0038] 2. Surface 300 mesh, shot blasting at a pressure of 0.5 MPa to remove surface oxides, and the roughened surface enhances the adhesion of the plated layer.

[0039] 3. Straightening treatment: mechanical straightening.

[0040] 4. Oil removal: sodium hydroxide 70 grams / liter, temperature: 75℃; time: 15 minutes, mode: flow immersion type.

[0041] 5. Pickling: hydrochloric acid 100 milliliters / liter; temperature: 15℃, time: 10 minutes, mode: flow immersion type.

[0042] 6. Activation: sulfuric acid 40 milliliters / liter and sodium fluoride 8 grams / liter; temperature: 15℃, time: 5 minutes, mode: flow immersion type.

[0043] 7. Surface plating thickness 3um metal platinum; dinitrosoplatinum diamine 5 grams / liter, ammonium citrate 3 grams / liter, sulfamic acid 20 grams / liter, ammonium sulfamate 10 grams / liter, PH value: 0.8 (ammonia water adjustment), temperature: 42℃, cathode current density 0.8 ampere / square decimeter, anode: metal platinum.

[0044] 8. Assembly processing: the electroplating anode 1 is externally processed with threads, the stop plug 2 is internally threaded, and the stop plug is screwed in to form a limiting block 3 (as shown in Figure 1 ) on the exposed part of the anode, which can withstand a large stop pulling force without loosening or falling off.

[0045] Example 3

[0046] A method for preparing an environmentally friendly electroplating anode assembly with a large aspect ratio and slender tube.

[0047] 1. Niobium rods (purity > 99.5%) are processed to the required dimensions through multi-stage cold drawing and hardening treatment, with a tensile strength of 800 MPa;

[0048] 2. Surface roughening treatment with 400 mesh and 0.6MPa pressure to remove surface oxides and roughen the surface to enhance the adhesion of the coating;

[0049] 3. Straightening process: Mechanical straightening;

[0050] 4. Degreasing: Sodium hydroxide 100 g / L, temperature: 80℃; time: 20 minutes, method: flowing immersion;

[0051] 5. Pickling: 150 ml / L hydrochloric acid; temperature: 25℃; time: 15 minutes; method: flowing immersion.

[0052] 6. Activation: 80 mL / L sulfuric acid, 12 g / L sodium fluoride; temperature: 25℃, time: 10 minutes, method: flowing immersion;

[0053] 7. Surface plating thickness 4µm metallic platinum; 5 g / L dinitrosodiammonium platinum, 6 g / L ammonium citrate, 20 g / L aminosulfonic acid, 6 g / L ammonium aminosulfonic acid, pH value: 1.2 (adjusted with ammonia), temperature: 40℃, cathode current density 0.5 amperes / dm², anode: metallic platinum;

[0054] 8. Component Processing: The electroplated anode 1 uses externally machined threads, while the stop plug 2 uses internal threads. After the stop plug is screwed in, the exposed portion of the anode is mechanically roughened to form a limiting block 3, which can withstand large stopping forces without loosening or slipping. Based on the insolubility of platinum, the anode shape is stable, the positioning is accurate, and the electroplated anode has a long service life.

[0055] Example 4

[0056] A method for preparing an environmentally friendly electroplating anode assembly with a large aspect ratio and slender tube.

[0057] 1. Niobium rods (purity > 99.5%) are processed to the required dimensions through multi-stage cold drawing and hardening treatment, with a tensile strength of 800 MPa;

[0058] 2. Surface roughening treatment with 300 mesh and 0.5MPa pressure to remove surface oxides and roughen the surface to enhance the adhesion of the coating;

[0059] 3. Straightening process: Mechanical straightening;

[0060] 4. Degreasing: Sodium hydroxide 85 g / L, temperature: 72℃; time: 18 minutes, method: flowing immersion;

[0061] 5. Pickling: 125 ml / L hydrochloric acid; temperature: 20℃; time: 18 minutes; method: flowing immersion.

[0062] 6. Activation: 45 mL / L sulfuric acid, 10 g / L sodium fluoride; temperature: 20℃, time: 7 minutes, method: flowing immersion;

[0063] 7. Surface plating thickness 3.5um metallic platinum; 8 g / L dinitrosodiammineplatinum, 4 g / L sodium citrate, 22 g / L aminosulfonic acid, 6 g / L ammonium aminosulfonate, pH value: 1.1 (adjusted with ammonia), temperature: 42℃, cathode current density 1 ampere / dm², anode: metallic platinum;

[0064] 8. Component Processing: The electroplated anode 1 uses externally machined threads, while the stop plug 2 uses internal threads. After the stop plug is screwed in, the exposed portion of the anode is mechanically roughened to form a limiting block 3, which can withstand large stopping forces without loosening or slipping. Based on the electrochemical properties of platinum, the electroplated anode can use positive / negative commutated electroplating currents, without electrode passivation.

[0065] Comparative Example 1

[0066] Titanium wire coated with platinum is used for electroplating anodes:

[0067] 1. Surface roughening treatment with 20 mesh and 0.4 MPa pressure to remove surface oxides and roughen the surface to enhance the adhesion of the coating;

[0068] 2. Correction Processing: Correction;

[0069] 3. Electrolytic degreasing: Sodium hydroxide 70 g / L, temperature 60℃; current density: 3 amperes / dm²; time 4 minutes;

[0070] 4. Pickling: 80 ml / L hydrochloric acid, 20 ml / L nitric acid, 20 ml / L hydrogen peroxide; temperature 15℃, time 10 minutes;

[0071] 5. Surface is coated with 3.5µm thick platinum metal;

[0072] Titanium has a resistivity of 42 μΩ / cm and poor conductivity, making it unsuitable for high-current applications, causing significant heat generation, and exhibiting longitudinal current decay at the anode. It is also unsuitable for electroplating anodes with large aspect ratios.

[0073] Comparative Example 2

[0074] Titanium wire coated with iridium oxide is used for electroplating anodes:

[0075] 1. Surface roughening treatment with 200 mesh and 0.4MPa pressure to remove surface oxides and roughen the surface to enhance the adhesion of the coating;

[0076] 2. Correction Processing: Correction;

[0077] 3. Electrolytic degreasing: Sodium hydroxide 70 g / L, temperature 60℃; current density: 3 amperes / dm²; time 5 minutes;

[0078] 4. Pickling: 80 ml / L hydrochloric acid, 30 ml / L nitric acid, 20 ml / L hydrogen peroxide; temperature 15℃, time 10 minutes;

[0079] 5. Apply iridium oxide slurry, bake at high temperature, apply iridium oxide slurry a second time, bake at high temperature, and repeat the above process 5-7 times.

[0080] Due to the electrochemical characteristics of iridium oxide plating, positive current can be used, but negative current cannot. It lacks positive / negative commutation current plating functionality. Iridium oxide plating is also soft and easily damaged, resulting in a short anode lifespan.

[0081] Comparative Example 3

[0082] Steel wire plated with lead / lead-tin alloy for use as anode in hexavalent chromium plating:

[0083] 1. Surface roughening treatment with 200 mesh and 0.6MPa pressure to remove surface oxides and roughen the surface to enhance the adhesion of the coating;

[0084] 2. Correction Processing: Correction;

[0085] 3. Electrolytic degreasing: Sodium hydroxide 70 g / L, temperature 60℃; current density: 3.5 amperes / dm²; time 4 minutes;

[0086] 4. Pickling: 80 ml / L hydrochloric acid; temperature 15℃, time 10 minutes;

[0087] 5. Plating metallic lead / lead-tin alloy 300um: lead methanesulfonate 80 g / L, tin methanesulfonate 4 g / L, methanesulfonic acid 40 g / L, temperature 40℃, current density: 3.5 amperes / dm²;

[0088] The preparation process of lead / lead-tin alloy anodes involves heavy metal lead contamination. The lead / lead-tin alloy plating layer is soft and easily damaged. When used as a hexavalent chromium electroplating anode, the lead chromate film on the surface transforms and detaches, resulting in lead plating loss and a short anode lifespan.

[0089] The electroplated anodes of Examples 1-4 and Comparative Examples 1-3 were subjected to performance tests, and the results are shown in the table below:

[0090]

[0091] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing an environmentally friendly electroplating anode with a large aspect ratio and slender tube shape, characterized in that, Prepare according to the following steps: S1: Niobium rods are processed to form niobium wires; S2: Physical and chemical treatment of niobium wire; S3: Metal coating on the treated niobium wire.

2. The method for preparing a high aspect ratio slender tube environmentally friendly electroplating anode as described in claim 1, characterized in that, In step S1, the niobium rod is specifically processed into niobium wire through a multi-stage cold drawing and hardening process.

3. The method for preparing a high aspect ratio slender tube environmentally friendly electroplating anode as described in claim 1, characterized in that, The physical treatment in step S2 includes shot peening and roughening, and mechanical straightening.

4. The method for preparing a high aspect ratio slender tube environmentally friendly electroplating anode as described in claim 1, characterized in that, The chemical treatment in step S2 includes degreasing, pickling, and activation in sequence.

5. The method for preparing a high aspect ratio slender tube environmentally friendly electroplating anode as described in claim 1, characterized in that, The chemical treatment in step S2 is carried out in the following steps: Sodium hydroxide was used to degrease the niobium wire; Hydrochloric acid was used to pickle the niobium wire; Surface activation of niobium wire was performed using sulfuric acid and sodium fluoride.

6. The method for preparing a high aspect ratio slender tube environmentally friendly electroplating anode as described in claim 1, characterized in that, In step S3, platinum is specifically plated onto the surface of the niobium wire.

7. The method for preparing a high aspect ratio slender tube environmentally friendly electroplating anode as described in claim 1, characterized in that, In step S3, a 3-4 μm metal platinum layer is deposited on the surface of the niobium wire.

8. A high aspect ratio slender tube environmentally friendly electroplating anode assembly, characterized in that, The device includes an electroplated anode and a stop plug. The stop plug is threaded onto one end of the electroplated anode. A limiting block is provided on one end of the electroplated anode. The limiting block is formed by upsetting the end of the electroplated anode. The electroplated anode is prepared using any one of the electroplated anode preparation methods as described in claims 1-7.

9. The environmentally friendly electroplating anode assembly with a large aspect ratio and slender tube as described in claim 8, characterized in that, The electroplated anode uses externally machined threads, while the stop plug uses internally machined threads.

10. The environmentally friendly electroplating anode assembly with a large aspect ratio and slender tube as described in claim 8, characterized in that, After the stop plug is screwed in, the exposed part of the anode is mechanically roughened to form a limiting block.

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