Process for electroplating nickel-tungsten alloy on threaded coupling

Abstract

The invention relates to the field of electroplating of threaded couplings, in particular to an electroplating nickel-tungsten alloy process for a threaded coupling. The nickel-tungsten alloy electroplating technology for the threaded coupling comprises the following steps that S1, activating treatment is conducted; s2, nickel pre-plating treatment; s3, copper plating treatment; s4, nickel-tungsten alloy plating treatment; s5, tinned copper treatment; and S6, passivating treatment is conducted. According to the composite electroplating technology for the threaded coupling, the abrasion resistance and corrosion resistance of the threaded part are improved through multi-stage coating superposition. Bottom-layer metal nickel is formed through nickel pre-plating treatment, and the binding force of a base body and a plating layer is enhanced; the copper plating layer can improve the ductility of the plating layer and reduce internal stress; the nickel-tungsten alloy layer improves the hardness and high-temperature stability of the plating layer; the tinned copper layer further prevents extrusion deformation of the threads, reduces the friction coefficient and prevents thread gluing; a compact oxidation film is formed through passivating treatment, and the color change phenomenon on the surface is prevented. And the service life of the coupling under the working conditions of high pressure and high friction is obviously prolonged.

Description

Technical Field

[0001] The present application relates to the field of electroplating of threaded collars, and in particular to an electroplating nickel-tungsten alloy process for threaded collars. Background Art

[0002] As an important component widely used in industrial fields such as petroleum and natural gas, the performance and quality of the collar directly affect the reliability and safety of the entire pipeline system. In order to improve the corrosion resistance, wear resistance and other related properties of the collar, surface treatment processes such as copper-tin alloy plating are widely used. By plating a copper-tin alloy layer on the surface of the collar, its service performance in harsh environments can be effectively enhanced and its service life can be extended.

[0003] In view of the above-mentioned prior art, the inventor found that, different from traditional collars, the threaded structure of the new type of collar is special, and the friction at the thread is more intense during actual use. However, in the design and implementation of the existing copper-tin alloy plating process, the influence brought by this special threaded structure is not fully considered, and the coating at the thread cannot effectively withstand the intense friction during actual use, thus reducing the overall service life and reliability of the collar. Summary of the Invention

[0004] In order to improve the above technical problems, the present application provides an electroplating nickel-tungsten alloy process for threaded collars.

[0005] An electroplating nickel-tungsten alloy process for threaded collars includes the following steps: S1. Activation treatment: Take the threaded collar to be electroplated, wash it clean, perform pickling activation treatment, and after the pickling activation treatment, wash it clean and collect the activated threaded collar; S2. Pre-nickel plating treatment: Place the activated threaded collar in a pre-plating tank for pre-nickel plating treatment, adjust the electroplating current and temperature, and after the pre-nickel plating treatment is completed, wash it clean and collect the pre-nickel plated threaded collar; S3. Copper plating treatment: Place the pre-nickel plated threaded collar in a plating tank for electroplating copper treatment, adjust the electroplating current and temperature, wash it clean, and prepare the electroplated copper threaded collar; S4. Nickel-tungsten alloy plating treatment: Then place the electroplated copper threaded collar in a plating tank for nickel-tungsten alloy plating treatment, adjust the electroplating current and temperature, wash it clean and collect the nickel-tungsten plated threaded collar; S5. Tin-copper plating treatment: Then place the nickel-tungsten plated threaded collar in a plating tank for tin-copper plating treatment, adjust the electroplating current and temperature, wash it clean and collect the tin-copper plated threaded collar; S6. Passivation treatment: Place the tin-copper plated threaded collar in a passivation tank, perform passivation treatment and washing, hang it down and dry it, and after inspection is completed, the electroplating nickel-tungsten alloy process for the threaded collar can be completed.

[0006] Through the above technical scheme, the technical scheme of this application is aimed at the composite electroplating process of threaded couplings, and the wear resistance and corrosion resistance of the threaded parts are improved by multi-stage coating superposition. Pre-nickel plating treatment forms the bottom metal nickel, which enhances the bonding force between the substrate and the subsequent coating, and blocks the direct contact between the copper layer and the steel substrate to inhibit electrochemical corrosion; the copper plating layer serves as an intermediate buffer layer, effectively improving the ductility of the coating and reducing the internal stress; the nickel-tungsten alloy layer improves the hardness and high-temperature stability of the coating through the solid solution strengthening effect, and simultaneously optimizes the friction coefficient; the tin-plated copper layer improves the surface finish through the lubricating properties of tin while enhancing the corrosion resistance; the passivation treatment forms a dense chromate conversion film, which closes the micropores of the coating to extend the protection period. This process is based on the dynamic friction characteristics of the threaded coupling, and solves the defects of weakened interface bonding and insufficient wear resistance in the traditional process through the synergistic effect of the coating system. The gradient design of the nickel-tungsten alloy and the tin-copper layer takes into account both mechanical properties and corrosion resistance requirements, and cooperates with the long-term protection mechanism of the passivation film to significantly improve the service life of the coupling under high pressure and high friction conditions.

[0007] Furthermore, the activation treatment in step S1 further includes an electrolytic degreasing step: S11, electrolytic degreasing: put the cleaned threaded coupling into a degreasing tank for electrolytic degreasing, control the temperature at 50-70°C, and degrease for 1-3 minutes to complete the electrolytic degreasing step.

[0008] Through the above technical scheme, the present application utilizes electrochemical action to enhance the degreasing effect, generates bubbles through electrode reaction in alkaline solution to flush the surface of the coupling, and effectively removes grease and particulate contaminants in the thread gap. Controlling the temperature at 50-70°C can accelerate the saponification reaction of the degreaser on grease, while avoiding unbalanced volatilization of the solution caused by excessive temperature; the degreasing time of 1-3min balances the cleaning efficiency and energy consumption, and prevents excessive treatment from damaging the substrate. Compared with conventional degreasing, electrolytic degreasing can clean the thread grooves and thread roots more thoroughly, reduce the burden of subsequent pickling activation, and avoid residual grease causing a decrease in the bonding strength of the coating. This step significantly improves the adhesion of the coating on the threaded part, reduces the problem of blistering or peeling of the coating caused by local contamination, and is especially suitable for surface pretreatment of high-precision threaded couplings.

[0009] Furthermore, in the electroplating solution used in the pre-nickel plating treatment in step S2, NiCl:HCl=(2.2-2.6):(1-1.5).

[0010] Through the above technical solution, the present application adjusts Cl - The concentration controls the nickel ion deposition rate and the grain size of the coating. A higher NiCl ratio can increase the conductivity of the plating solution, reduce the cell voltage, and reduce energy consumption; HCl maintains the acidity of the solution to prevent Ni 2+Hydrolysis generates precipitation while inhibiting the risk of hydrogen embrittlement. After optimizing the ratio, the pre-plated nickel layer has a stronger bonding force with the threaded substrate, avoiding cracks or peeling caused by internal stress in the coating. In addition, the uniform nickel layer can cover the microscopic defects on the threaded surface, reducing the porosity of the subsequent copper plating and nickel-tungsten alloy plating, and improving the overall coating protection performance, especially suitable for threaded couplings under high-friction working conditions.

[0011] Furthermore, the copper plating solution used in the copper plating treatment in step S3 includes the following substances by weight in grams: CuCN 30 - 50 g; NaCN 8 - 18 g; NaOH 8 - 15 g.

[0012] Through the above technical solution, in this application, CuCN in the copper plating solution provides copper ions, and NaCN acts as a complexing agent to stabilize Cu⁺ and prevent the oxidation of copper ions to Cu 2+ resulting in the failure of the plating solution; NaOH adjusts the pH value and enhances the conductivity. The concentration of CuCN is moderate to avoid rough coatings caused by excessive concentration; the synergistic effect of NaCN and NaOH maintains the stability of the solution and prevents the decomposition of cyanide to produce toxic gases. This formulation forms a dense copper layer on the threaded surface, filling the gaps in the thread profile and reducing the stress concentration in the subsequent nickel-tungsten alloy coating. The high ductility of the copper layer can buffer the local impact during thread friction, reduce the risk of coating cracking, and at the same time provide a good conductive substrate for the subsequent coating to ensure the uniform deposition of the nickel-tungsten alloy and tin-copper layers.

[0013] Furthermore, the nickel-tungsten plating solution in step S4 includes a sodium tungstate-nickel sulfate mixed solution in a mass ratio of (3.5 - 5.0):(10 - 20).

[0014] Through the above technical solution, in this application, sodium tungstate and nickel sulfate are mixed. Nickel sulfate provides the main nickel ion salt, and sodium tungstate serves as the tungsten source to form a Ni-W alloy through co-deposition. If the proportion of sodium tungstate is too low, the tungsten content in the coating will be insufficient and the hardness will decrease; if the proportion is too high, the plating solution may become turbid due to the solubility limit of tungstate. At this ratio, the tungsten content in the coating is moderate, forming an amorphous structure with both high hardness and corrosion resistance. The Ni-W alloy layer significantly improves the wear resistance and high-temperature stability of the threaded part. Its hardness far exceeds that of pure nickel or copper layers and can withstand severe friction and local high temperatures. The amorphous structure reduces the corrosion path at grain boundaries and enhances the corrosion resistance.

[0015] Furthermore, the plating solution used in the tin-copper plating treatment in step S5 includes the following substances by weight in grams: CuCN 20 - 25 g; Na2SnO3 18 - 20 g; NaCN 18 - 23 g; NaOH 8 - 12 g.

[0016] Through the above technical solution, in this application, CuCN and Na2SnO3 in the plating solution respectively provide copper and tin ions, NaCN complexes metal ions to prevent hydrolysis, and NaOH maintains an alkaline environment. Sn exists in the form of stannate and co-deposits with Cu to form a Cu-Sn alloy, where the tin content optimizes the corrosion resistance and surface finish of the coating. The tin-copper alloy layer has excellent corrosion resistance and a low friction coefficient, which can reduce the frictional resistance during thread meshing, and at the same time seal the micro-pores of the nickel-tungsten alloy layer to prevent the penetration of the medium and cause bottom-layer corrosion. The surface of this coating is smooth, reducing the torque fluctuation and galling phenomenon during thread assembly and improving the sealing performance.

[0017] Further, the passivation treatment in step S6 is a CrO3 passivation solution with a mass concentration of 30 - 50 g / L.

[0018] Through the above technical solution, this application selects a CrO3 passivation solution as the passivating agent, which reacts with the coating surface under acidic conditions to form a mixed oxide film of Cr(OH)3 and Cr2O3, sealing the coating pores and improving the corrosion resistance. When the concentration is lower than 30 g / L, the passivation film is too thin and the protection effect is insufficient; when it is higher than 50 g / L, it may cause environmental pollution and operation risks due to the increase in the toxicity of Cr ions. This application significantly improves the salt spray resistance and hydrogen sulfide corrosion resistance of the coating through the passivation film, especially in marine or sulfur-containing oil and gas environments, it can extend the life of the coupling. In addition, the friction coefficient of the thread surface after passivation treatment is further reduced, reducing the wear during assembly.

[0019] Further, the pickling and activation treatment in step S1 uses an HCl solution with a mass fraction concentration of 30 - 60%.

[0020] Through the above technical solution, this application removes the oxide film and slight rust on the coupling surface through strong acid corrosion, and at the same time micro-roughens the substrate surface to enhance the adhesion of the coating. The optimized HCl concentration ensures that the thread surface is clean and moderately roughened, improving the bonding strength between the pre-plated nickel layer and the substrate, and avoiding local peeling of the coating caused by insufficient activation.

[0021] In summary, this application has the following beneficial effects: First, the technical solution of this application is aimed at the composite electroplating process of threaded couplings, and the wear resistance and corrosion resistance of the threaded parts are improved by superposition of multi-stage coatings. Pre-nickel plating forms the bottom metal nickel, which enhances the bonding force between the substrate and the subsequent coating, and blocks the direct contact between the copper layer and the steel substrate to inhibit electrochemical corrosion; the copper plating layer serves as an intermediate buffer layer, effectively improving the ductility of the coating and reducing internal stress; the nickel-tungsten alloy layer improves the hardness and high-temperature stability of the coating through the solid solution strengthening effect, and simultaneously optimizes the friction coefficient; the tin-plated copper layer improves the surface finish through the lubricating properties of tin while enhancing the corrosion resistance; the passivation treatment forms a dense chromate conversion film, which closes the micropores of the coating to extend the protection period. This process is based on the dynamic friction characteristics of the threaded coupling, and solves the defects of weakened interface bonding and insufficient wear resistance in the traditional process through the synergistic effect of the coating system. The gradient design of the nickel-tungsten alloy and the tin-copper layer takes into account both mechanical properties and corrosion resistance requirements, and cooperates with the long-term protection mechanism of the passivation film to significantly improve the service life of the coupling under high pressure and high friction conditions.

[0022] Second, this application adjusts Cl - The concentration controls the nickel ion deposition rate and the grain size of the coating. A higher NiCl ratio can increase the conductivity of the plating solution, reduce the cell voltage, and reduce energy consumption; HCl maintains the acidity of the solution to prevent Ni 2+ Hydrolysis generates precipitation, while suppressing the risk of hydrogen embrittlement. The pre-plated nickel layer with optimized ratio has stronger bonding with the thread matrix, avoiding cracks or peeling caused by internal stress in the plating layer. In addition, the uniform nickel layer can cover the microscopic defects on the thread surface, reduce the porosity of subsequent copper plating and nickel-tungsten alloy, and improve the overall coating protection performance, especially suitable for threaded couplings under high friction conditions.

[0023] Third, the present invention provides copper ions through CuCN in the copper plating solution, and NaCN is used as a complexing agent to stabilize Cu + , to prevent copper ions from being oxidized to Cu 2+ The solution is ineffective; NaOH adjusts the pH value and enhances conductivity. The CuCN concentration is moderate to avoid rough coating due to excessive concentration; the synergistic effect of NaCN and NaOH maintains the stability of the solution and prevents cyanide from decomposing and producing toxic gases. The formula forms a dense copper layer on the thread surface, filling the thread tooth gap and reducing the stress concentration of the subsequent nickel-tungsten alloy coating. The high ductility of the copper layer can buffer the local impact during thread friction and reduce the risk of coating cracking. At the same time, it provides a good conductive base for subsequent coatings and ensures the uniform deposition of nickel-tungsten alloy and tin-copper layers.

[0024] Fourth, in this application, sodium tungstate and nickel sulfate are mixed. Nickel sulfate provides the main nickel ion salt, and sodium tungstate serves as the tungsten source. The Ni-W alloy is formed through co-deposition. If the proportion of sodium tungstate is too low, the tungsten content in the coating will be insufficient and the hardness will decrease; if the proportion is too high, the plating solution may become turbid due to the solubility limit of tungstate. At this proportion, the tungsten content in the coating is moderate, forming an amorphous structure, which has both high hardness and corrosion resistance. The Ni-W alloy layer significantly improves the wear resistance and high-temperature stability of the threaded part. Its hardness far exceeds that of pure nickel or copper layers and can withstand severe friction and local high temperatures. The amorphous structure reduces the corrosion path at grain boundaries and enhances the corrosion resistance. Detailed implementation manners

[0025] The following further elaborates on this application in conjunction with embodiments.

[0026] Preparation examples Preparation example 1 Pre-plated nickel electroplating solution 1 According to NiCl:HCl = 2.2:1, take NiCl and hydrochloric acid, stir and mix them to prepare pre-plated nickel electroplating solution 1.

[0027] Preparation example 2 Pre-plated nickel electroplating solution 2 According to NiCl:HCl = 2.4:1.2, take NiCl and hydrochloric acid, stir and mix them to prepare pre-plated nickel electroplating solution 2.

[0028] Preparation example 3 Pre-plated nickel electroplating solution 3 According to NiCl:HCl = 2.6:1.5, take NiCl and hydrochloric acid, stir and mix them to prepare pre-plated nickel electroplating solution 3.

[0029] Preparation example 4 Copper plating solution 1 Take 30 g of CuCN, 8 g of NaCN, 8 g of NaOH and 1000 mL of water, stir and mix them to prepare copper plating solution 1.

[0030] Preparation example 5 Copper plating solution 2 Take 40 g of CuCN, 13 g of NaCN, 11 g of NaOH and 1000 mL of water, stir and mix them to prepare copper plating solution 2.

[0031] Preparation example 6 Copper plating solution 3 Take 50 g of CuCN, 18 g of NaCN, 15 g of NaOH and 1000 mL of water, stir and mix them to prepare copper plating solution 3.

[0032] Preparation example 7 According to the mass ratio of 3.5:10, take sodium tungstate and nickel sulfate, place them in 1000 g of water, stir and mix them to prepare sodium tungstate-nickel sulfate mixture 1.

[0033] Preparation Example 8 Sodium tungstate and nickel sulfate were taken in a mass ratio of 4:15 and placed in 1000 g of water, stirred and mixed to prepare sodium tungstate-nickel sulfate mixed solution 2.

[0034] Preparation Example 9 Sodium tungstate and nickel sulfate were taken in a mass ratio of 5:20 and placed in 1000 g of water, stirred and mixed to prepare sodium tungstate-nickel sulfate mixed solution 3.

[0035] Preparation Example 10 Tin-plated copper electroplating solution 1 20 g of CuCN, 18 g of Na2SnO3, 18 g of NaCN and 8 g of NaOH were taken and placed in 1000 g of water, stirred and mixed to prepare tin-plated copper electroplating solution 1.

[0036] Preparation Example 11 Tin-plated copper electroplating solution 2 22 g of CuCN, 19 g of Na2SnO3, 20 g of NaCN and 10 g of NaOH were taken and placed in 1000 g of water, stirred and mixed to prepare tin-plated copper electroplating solution 2.

[0037] Preparation Example 12 Tin-plated copper electroplating solution 3 25 g of CuCN, 20 g of Na2SnO3, 23 g of NaCN and 12 g of NaOH were taken and placed in 1000 g of water, stirred and mixed to prepare tin-plated copper electroplating solution 3.

[0038] Example 1 S1. Activation treatment: The threaded coupling to be electroplated was washed with a pH 9-10 ultrasonic cleaning agent for 5 min to remove surface oil stains. The threaded coupling after rinsing with clean water was immersed in a 30% mass fraction HCl solution at 25 °C for pickling and activation for 2 min. After pickling and activation treatment, it was rinsed 3 times with deionized water to collect the activated threaded coupling; S2. Pre-nickel plating treatment: The activated threaded coupling was placed in a pre-plating tank, and pre-nickel plating electroplating solution 1 was added for pre-nickel plating treatment. The electroplating current was adjusted to 3 A / dm 2 , at room temperature. After 8 min of electroplating treatment, it was rinsed 2 times with deionized water to obtain a pre-nickel plated threaded coupling; S3. Copper plating treatment: The pre-nickel plated threaded coupling was placed in a plating tank, copper plating solution 1 was added and copper plating treatment was carried out. The current density was adjusted to 2.5 A / dm², the temperature was 55 °C, and the electroplating time was 5 min. After electroplating, it was washed with water to obtain a copper plated threaded coupling; S4. Nickel-tungsten alloy plating treatment: Then the copper plated threaded coupling was placed in a plating tank, and sodium tungstate-nickel sulfate mixed solution 1 was added for nickel-tungsten alloy plating treatment. The current density was adjusted to 1.5 A / dm2 , at a temperature of 60 °C and an electroplating time of 60 min, wash it clean and collect the nickel-tungsten plated threaded coupling; S5. Tin-copper plating treatment: Then place the nickel-tungsten plated threaded coupling in a plating bath, add tin-copper plating solution 1 for tin-copper plating treatment, and adjust the electroplating current to 1.8 A / dm 2 , at a temperature of 58 °C, electroplate for 50 min, wash it clean and collect the tin-copper plated threaded coupling; S6. Passivation treatment: Place the tin-copper plated threaded coupling in a passivation bath, add a 30 g / L CrO3 passivation solution for passivation, hang it down to dry. After inspection is completed, the electroplating nickel-tungsten alloy process for the threaded coupling can be completed.

[0039] Example 2 S1. Activation treatment: Take the threaded coupling to be electroplated, wash it with a pH 9 - 10 ultrasonic cleaning agent for 5 min to remove surface oil stains. Immerse the threaded coupling after rinsing with clean water in a 45% mass fraction HCl solution at a temperature of 25 °C for pickling activation for 2 min. After pickling activation treatment, rinse it 3 times with deionized water and collect the activated treated threaded coupling; S2. Nickel pre-plating treatment: Take the activated treated threaded coupling and place it in a pre-plating bath, add pre-plating nickel plating solution 2 for nickel pre-plating treatment, and adjust the electroplating current to 3 A / dm 2 , at room temperature, after electroplating treatment for 8 min, rinse it 2 times with deionized water to obtain the nickel pre-plated threaded coupling; S3. Copper plating treatment: Take the nickel pre-plated threaded coupling and place it in a plating bath, add copper plating solution 1 and perform copper plating treatment. Adjust the current density to 2.5 A / dm², at a temperature of 55 °C, electroplate for 5 min, and wash it with water after electroplating to obtain the copper plated threaded coupling; S4. Nickel-tungsten alloy plating treatment: Then place the copper plated threaded coupling in a plating bath, add sodium tungstate-nickel sulfate mixture 1 for nickel-tungsten alloy plating treatment, and adjust the current density to 1.5 A / dm 2 , at a temperature of 60 °C, electroplate for 60 min, wash it clean and collect the nickel-tungsten plated threaded coupling; S5. Tin-copper plating treatment: Then place the nickel-tungsten plated threaded coupling in a plating bath, add tin-copper plating solution 1 for tin-copper plating treatment, and adjust the electroplating current to 1.8 A / dm 2 , at a temperature of 58 °C, electroplate for 50 min, wash it clean and collect the tin-copper plated threaded coupling; S6. Passivation treatment: Place the tin-copper plated threaded coupling in a passivation bath, add a 40 g / L CrO3 passivation solution for passivation, hang it down to dry. After inspection is completed, the electroplating nickel-tungsten alloy process for the threaded coupling can be completed.

[0040] Example 3 S1. Activation treatment: Take the threaded coupling to be electroplated and wash it with an ultrasonic cleaning agent with a pH of 9 - 10 for 5 minutes to remove the surface oil. After rinsing with clean water, immerse the threaded coupling in an HCl solution with a temperature of 25°C and a mass fraction of 60% for pickling and activation for 2 minutes. After pickling and activation treatment, rinse it 3 times with deionized water, and collect the activated threaded coupling; S2. Pre - nickel plating treatment: Take the activated threaded coupling and place it in a pre - plating tank, add pre - nickel plating electroplating solution 3 for pre - nickel plating treatment, adjust the electroplating current to 3 A / dm 2 , at room temperature. After electroplating for 8 minutes, rinse it 2 times with deionized water to obtain the pre - nickel plated threaded coupling; S3. Copper plating treatment: Take the pre - nickel plated threaded coupling and place it in a plating tank, add copper plating solution 1 and carry out copper plating treatment. Adjust the current density to 2.5 A / dm², temperature to 55°C, electroplating time to 5 minutes. After electroplating, wash it with water to obtain the copper - plated threaded coupling; S4. Nickel - tungsten alloy plating treatment: Then place the copper - plated threaded coupling in a plating tank, add sodium tungstate - nickel sulfate mixture 1 for nickel - tungsten alloy plating treatment. Adjust the current density to 1.5 A / dm2, temperature to 60°C, electroplating time to 60 minutes. Wash it clean and collect the nickel - tungsten plated threaded coupling; S5. Tin - copper plating treatment: Then place the nickel - tungsten plated threaded coupling in a plating tank and add tin - copper electroplating solution 1 for tin - copper plating treatment. Adjust the electroplating current to 1.8 A / dm 2 , temperature to 58°C, electroplating for 50 minutes. Wash it clean and collect the tin - copper plated threaded coupling; S6. Passivation treatment: Place the tin - copper plated threaded coupling in a passivation tank, add a passivation solution of 50 g / L CrO3 for passivation, hang it down to dry. After inspection is completed, the electroplating process of nickel - tungsten alloy for the threaded coupling can be completed.

[0041] Example 4 S1. Activation treatment: Take the threaded coupling to be electroplated and wash it with an ultrasonic cleaning agent with a pH of 9 - 10 for 5 minutes to remove the surface oil. After rinsing with clean water, immerse the threaded coupling in an HCl solution with a temperature of 25°C and a mass fraction of 45% for pickling and activation for 2 minutes. After pickling and activation treatment, rinse it 3 times with deionized water, and collect the activated threaded coupling; S2. Pre - nickel plating treatment: Take the activated threaded coupling and place it in a pre - plating tank, add pre - nickel plating electroplating solution 2 for pre - nickel plating treatment, adjust the electroplating current to 3 A / dm 2 , at room temperature. After electroplating for 8 minutes, rinse it 2 times with deionized water to obtain the pre - nickel plated threaded coupling; S3. Copper plating treatment: Place the pre-nickel-plated threaded coupling in a plating bath, add copper plating solution 2 and perform copper plating treatment by electroplating. Adjust the current density to 2.5 A / dm², the temperature to 55 °C, and the electroplating time to 5 min. After electroplating, wash with water and dry to obtain an electroplated copper threaded coupling; S4. Nickel-tungsten alloy plating treatment: Then place the electroplated copper threaded coupling in a plating bath, add sodium tungstate-nickel sulfate mixed solution 1 for nickel-tungsten alloy plating treatment. Adjust the current density to 1.5 A / dm2, the temperature to 60 °C, and the electroplating time to 60 min. Wash clean and collect to obtain a nickel-tungsten-plated threaded coupling; S5. Tin-copper plating treatment: Then place the nickel-tungsten-plated threaded coupling in a plating bath and add tin-copper electroplating solution 1 for tin-copper plating treatment. Adjust the electroplating current to 1.8 A / dm 2 , the temperature is 58 °C, electroplate for 50 min, wash clean and collect to obtain a tin-copper-plated threaded coupling; S6. Passivation treatment: Place the tin-copper-plated threaded coupling in a passivation bath, add a 40 g / L CrO3 passivation solution for passivation, hang it down and dry. After inspection is completed, the electroplating nickel-tungsten alloy process for the threaded coupling can be completed.

[0042] Example 5 S1. Activation treatment: Take the threaded coupling to be electroplated and wash it with a pH 9 - 10 ultrasonic cleaning agent for 5 min to remove surface oil stains. Immerse the threaded coupling after rinsing with clean water in a 45% HCl solution at a temperature of 25 °C for pickling and activation for 2 min. After pickling and activation treatment, rinse with deionized water 3 times and collect to obtain an activated threaded coupling; S2. Pre-nickel plating treatment: Take the activated threaded coupling and place it in a pre-plating bath, add pre-nickel plating solution 2 for pre-nickel plating treatment. Adjust the electroplating current to 3 A / dm 2 , the temperature is room temperature. After electroplating treatment for 8 min, rinse with deionized water 2 times to obtain a pre-nickel-plated threaded coupling; S3. Copper plating treatment: Place the pre-nickel-plated threaded coupling in a plating bath, add copper plating solution 3 and perform copper plating treatment by electroplating. Adjust the current density to 2.5 A / dm², the temperature to 55 °C, and the electroplating time to 5 min. After electroplating, wash with water and dry to obtain an electroplated copper threaded coupling; S4. Nickel-tungsten alloy plating treatment: Then place the electroplated copper threaded coupling in a plating bath, add sodium tungstate-nickel sulfate mixed solution 1 for nickel-tungsten alloy plating treatment. Adjust the current density to 1.5 A / dm2, the temperature to 60 °C, and the electroplating time to 60 min. Wash clean and collect to obtain a nickel-tungsten-plated threaded coupling; S5. Tin-copper plating treatment: Then place the nickel-tungsten-plated threaded coupling in a plating bath and add tin-copper electroplating solution 1 for tin-copper plating treatment. Adjust the electroplating current to 1.8 A / dm 2 , the temperature is 58 °C, electroplate for 50 min, wash clean and collect to obtain a tin-copper-plated threaded coupling; S6. Passivation treatment: Place the tin-plated copper threaded coupling in a passivation tank, add a CrO3 passivation solution with a concentration of 40 g / L for passivation, hang it up for drying. After inspection is completed, the electroplating nickel-tungsten alloy process for the threaded coupling can be completed.

[0043] Example 6 S1. Activation treatment: Take the threaded coupling to be electroplated and wash it with an ultrasonic cleaner with a pH of 9 - 10 for 5 minutes to remove surface oil stains. After rinsing with clean water, immerse the threaded coupling in a 45% HCl solution at a temperature of 25 °C for pickling and activation for 2 minutes. After pickling and activation treatment, rinse it 3 times with deionized water to obtain the activated threaded coupling. S2. Pre-nickel plating treatment: Place the activated threaded coupling in a pre-plating tank, add pre-nickel plating electroplating solution 2 for pre-nickel plating treatment, adjust the electroplating current to 3 A / dm 2 , at room temperature. After electroplating treatment for 8 minutes, rinse it 2 times with deionized water to obtain the pre-nickel plated threaded coupling. S3. Copper plating treatment: Place the pre-nickel plated threaded coupling in a plating tank, add copper plating solution 2 and carry out copper plating treatment, adjust the current density to 2.5 A / dm², the temperature is 55 °C, the electroplating time is 5 minutes. After electroplating, wash it with water and dry it to obtain the electroplated copper threaded coupling. S4. Nickel-tungsten alloy plating treatment: Then place the electroplated copper threaded coupling in a plating tank, add a sodium tungstate - nickel sulfate mixed solution 2 for nickel-tungsten alloy plating treatment, adjust the current density to 1.5 A / dm2, the temperature is 60 °C, the electroplating time is 60 minutes, wash it clean and collect the nickel-tungsten plated threaded coupling. S5. Tin-copper plating treatment: Then place the nickel-tungsten plated threaded coupling in a plating tank, add tin-copper plating electroplating solution 1 for tin-copper plating treatment, adjust the electroplating current to 1.8 A / dm 2 , the temperature is 58 °C, electroplate for 50 minutes, wash it clean and collect the tin-copper plated threaded coupling. S6. Passivation treatment: Place the tin-copper plated threaded coupling in a passivation tank, add a CrO3 passivation solution with a concentration of 40 g / L for passivation, hang it up for drying. After inspection is completed, the electroplating nickel-tungsten alloy process for the threaded coupling can be completed.

[0044] Example 7 S1. Activation treatment: Take the threaded coupling to be electroplated and wash it with an ultrasonic cleaner with a pH of 9 - 10 for 5 minutes to remove surface oil stains. After rinsing with clean water, immerse the threaded coupling in a 45% HCl solution at a temperature of 25 °C for pickling and activation for 2 minutes. After pickling and activation treatment, rinse it 3 times with deionized water to obtain the activated threaded coupling. S2. Pre-nickel plating treatment: Place the activated threaded coupling in a pre-plating tank, add pre-nickel plating electroplating solution 2 for pre-nickel plating treatment, adjust the electroplating current to 3 A / dm 2, at room temperature, after electroplating for 8 minutes, rinse twice with deionized water to obtain a pre-plated nickel threaded coupling; S3. Copper plating treatment: Place the pre-plated nickel threaded coupling in a plating bath, add copper plating solution 2 and perform copper plating treatment. Adjust the current density to 2.5 A / dm², the temperature to 55 °C, and the electroplating time to 5 minutes. After electroplating, wash with water and dry to obtain a copper-plated threaded coupling; S4. Nickel-tungsten alloy plating treatment: Then place the copper-plated threaded coupling in a plating bath, add a sodium tungstate-nickel sulfate mixture 3 for nickel-tungsten alloy plating treatment. Adjust the current density to 1.5 A / dm2, the temperature to 60 °C, and the electroplating time to 60 minutes. Wash clean and collect to obtain a nickel-tungsten plated threaded coupling; S5. Tin-copper plating treatment: Then place the nickel-tungsten plated threaded coupling in a plating bath and add tin-copper electroplating solution 1 for tin-copper plating treatment. Adjust the electroplating current to 1.8 A / dm 2 , at a temperature of 58 °C, electroplate for 50 minutes, wash clean and collect to obtain a tin-copper plated threaded coupling; S6. Passivation treatment: Place the tin-copper plated threaded coupling in a passivation bath, add a 40 g / L CrO3 passivation solution for passivation, hang it down and dry. After inspection is completed, the electroplating nickel-tungsten alloy process for the threaded coupling can be completed.

[0045] Example 8 S1. Activation treatment: Take the threaded coupling to be electroplated and wash it with a pH 9-10 ultrasonic cleaning agent for 5 minutes to remove surface oil. Immerse the threaded coupling after rinsing with clean water in a 45% mass fraction HCl solution at a temperature of 25 °C for pickling and activation for 2 minutes. After pickling and activation treatment, rinse three times with deionized water and collect to obtain an activated threaded coupling; S2. Pre-plated nickel treatment: Place the activated threaded coupling in a pre-plating bath, add pre-plated nickel electroplating solution 2 for pre-plated nickel treatment. Adjust the electroplating current to 3 A / dm 2 , at room temperature, after electroplating for 8 minutes, rinse twice with deionized water to obtain a pre-plated nickel threaded coupling; S3. Copper plating treatment: Place the pre-plated nickel threaded coupling in a plating bath, add copper plating solution 2 and perform copper plating treatment. Adjust the current density to 2.5 A / dm², the temperature to 55 °C, and the electroplating time to 5 minutes. After electroplating, wash with water and dry to obtain a copper-plated threaded coupling; S4. Nickel-tungsten alloy plating treatment: Then place the copper-plated threaded coupling in a plating bath, add a sodium tungstate-nickel sulfate mixture 2 for nickel-tungsten alloy plating treatment. Adjust the current density to 1.5 A / dm2, the temperature to 60 °C, and the electroplating time to 60 minutes. Wash clean and collect to obtain a nickel-tungsten plated threaded coupling; S5. Tin-copper plating treatment: Then place the nickel-tungsten plated threaded coupling in a plating bath and add tin-copper electroplating solution 2 for tin-copper plating treatment. Adjust the electroplating current to 1.8 A / dm 2, at a temperature of 58°C, electroplate for 50 minutes, wash thoroughly and collect the tin-plated copper threaded coupling; S6. Passivation treatment: Place the tin-plated copper threaded coupling in a passivation tank, add a CrO3 passivation solution at 40 g / L for passivation, hang it up to dry. After inspection is completed, the electroplating nickel-tungsten alloy process for the threaded coupling can be completed.

[0046] Example 9 S1. Activation treatment: Take the threaded coupling to be electroplated and wash it with a pH 9 - 10 ultrasonic cleaning agent for 5 minutes to remove surface oil stains. Immerse the threaded coupling after rinsing with clean water in a HCl solution with a temperature of 25°C and a mass fraction of 45% for pickling and activation for 2 minutes. After pickling and activation treatment, rinse it 3 times with deionized water and collect the activated threaded coupling; S2. Pre-nickel plating treatment: Place the activated threaded coupling in a pre-plating tank, add pre-nickel plating solution 2 for pre-nickel plating treatment, adjust the electroplating current to 3 A / dm 2 , at room temperature, after electroplating for 8 minutes, rinse it 2 times with deionized water to obtain the pre-nickel plated threaded coupling; S3. Copper plating treatment: Place the pre-nickel plated threaded coupling in a plating tank, add copper plating solution 2 and carry out copper plating treatment, adjust the current density to 2.5 A / dm², at a temperature of 55°C, electroplate for 5 minutes, wash and dry after electroplating to obtain the copper-plated threaded coupling; S4. Nickel-tungsten alloy plating treatment: Then place the copper-plated threaded coupling in a plating tank, add sodium tungstate-nickel sulfate mixture 2 for nickel-tungsten alloy plating treatment, adjust the current density to 1.5 A / dm2, at a temperature of 60°C, electroplate for 60 minutes, wash thoroughly and collect the nickel-tungsten plated threaded coupling; S5. Tin-copper plating treatment: Then place the nickel-tungsten plated threaded coupling in a plating tank, add tin-copper plating solution 3 for tin-copper plating treatment, adjust the electroplating current to 1.8 A / dm 2 , at a temperature of 58°C, electroplate for 50 minutes, wash thoroughly and collect the tin-plated copper threaded coupling; S6. Passivation treatment: Place the tin-plated copper threaded coupling in a passivation tank, add a CrO3 passivation solution at 40 g / L for passivation, hang it up to dry. After inspection is completed, the electroplating nickel-tungsten alloy process for the threaded coupling can be completed.

[0047] Performance testing The parameters of the threaded couplings used in Examples 1 - 9 are shown in Table 1.

[0048] Table 1 Material and specification parameters of the pipe body and couplings

[0049] After performing 9 make-and-break tests on the threaded couplings in Examples 1-9, the corrosion resistance tests were then carried out on the corrosion-resistant composite pipes in Examples 1-9, and the test conditions are shown in Table 2 Table 2 Corrosion test conditions

[0050] After the immersion corrosion tests for 168 h, 200 h, and 400 h, the specimens were taken out, longitudinally sectioned according to four quadrants, and then the pipe body was separated from the coupling, and the surface and coating conditions of each part were observed, as shown in Table 3 below Table 3 Performance detection table Salt spray test: Detect according to standard ASTM B117; Wear resistance test: Detect according to ASTM G133; Adhesion test: Detect according to ASTM D3359.

[0051] The detection results are shown in Table 2 below: Table 3 Performance detection table

[0052] It can be found from the data of the examples that for the composite electroplating process of the threaded coupling in this application, the wear resistance and corrosion resistance of the threaded part are improved by multi-stage coating superposition. The pre-plated nickel treatment forms the bottom metal nickel, enhances the bonding force between the matrix and the subsequent coatings, and prevents the electrochemical corrosion that may be caused by the direct contact between the copper layer and the steel matrix; the copper plating layer is used as the intermediate layer, which can improve the ductility of the coating and reduce the internal stress; the nickel-tungsten alloy layer improves the hardness and high-temperature stability of the coating by introducing tungsten elements and reduces the friction coefficient; the tin-copper plating layer further improves the corrosion resistance and optimizes the surface finish at the same time; the passivation treatment forms a dense oxide film to seal the pores of the coating and extend the protection life. This process addresses the special friction requirements of the threaded coupling and, through the synergistic effect of multiple coatings, solves the problems of easy peeling and insufficient wear resistance of the coatings in the threaded part in the traditional process. The combination of the nickel-tungsten alloy and the tin-copper layer not only ensures high hardness but also enhances the corrosion resistance through the passivation film, which can significantly extend the service life of the coupling under high-pressure and high-friction working conditions.

[0053] This specific embodiment is only an interpretation of this application, and it is not a limitation of this application. Those skilled in the art can make modifications to this embodiment without creative contributions according to needs after reading this specification, but as long as it is within the scope of the claims of this application, it is protected by the patent law.

Claims

1. An electroplating nickel-tungsten alloy process for a threaded coupling, characterized in that, It includes the following steps: S1. Activation treatment: After washing the threaded casing to be electroplated clean, perform pickling activation treatment. After the pickling activation treatment, wash it clean and collect the activated threaded casing; S2. Pre-nickel plating treatment: Place the activated threaded casing in a pre-plating tank for pre-nickel plating treatment, adjust the electroplating current and temperature. After the pre-nickel plating treatment is completed, wash it clean and collect the pre-nickel-plated threaded casing; S3. Copper plating treatment: Place the pre-nickel-plated threaded casing in a plating tank for electroplating copper treatment, adjust the electroplating current and temperature, wash it clean, and prepare the copper-plated threaded casing; S4. Nickel-tungsten alloy plating treatment: Then place the copper-plated threaded casing in a plating tank for nickel-tungsten alloy plating treatment, adjust the electroplating current and temperature, wash it clean and collect the nickel-tungsten-plated threaded casing; S5. Tin-copper plating treatment: Then place the nickel-tungsten-plated threaded casing in a plating tank for tin-copper plating treatment, adjust the electroplating current and temperature, wash it clean and collect the tin-copper-plated threaded casing; S6. Passivation treatment: Place the tin-copper-plated threaded casing in a passivation tank for passivation treatment and washing. After hanging it down and drying, after inspection is completed, the electroplating nickel-tungsten alloy process for the threaded casing can be completed.

2. The electroplating nickel-tungsten alloy process for a threaded coupling according to claim 1, wherein The activation treatment described in step S1 further includes an electrolytic degreasing step: S11. Electrolytic degreasing: Place the washed threaded casing in a degreasing tank for electrolytic degreasing, control the temperature at 50 - 70 °C, and degrease for 1 - 3 minutes to complete the electrolytic degreasing step.

3. A nickel-tungsten alloy electroplating process for threaded collars according to claim 1, characterized in that, In the pre-nickel plating treatment described in step S2, the electroplating solution used has NiCl:HCl = (2.2 - 2.6):(1 - 1.5).

4. A nickel-tungsten alloy electroplating process for threaded couplings according to claim 1, characterized in that, The copper plating solution used in the copper plating treatment described in step S3 includes the following substances by weight: CuCN 30 - 50 g; NaCN 8 - 18 g; NaOH 8 - 15 g.

5. A nickel-tungsten alloy electroplating process for threaded collars, characterized in that, The nickel-tungsten plating solution described in step S4 includes a sodium tungstate-nickel sulfate mixed solution with a mass ratio of (3.5 - 5.0):(10 - 20).

6. A nickel-tungsten alloy electroplating process for threaded couplings according to claim 1, characterized in that, The plating solution used in the tin-copper plating treatment described in step S5 includes the following substances by weight: CuCN 20 - 25 g; Na2SnO3 18 - 20 g; NaCN 18 - 23 g; NaOH 8 - 12 g.

7. A nickel-tungsten alloy electroplating process for threaded couplings according to claim 1, characterized in that, The passivation treatment described in step S6 is a CrO3 passivation solution with a mass concentration of 30 - 50 g / L.

8. A nickel-tungsten alloy electroplating process for threaded couplings according to claim 1, characterized in that The pickling activation treatment described in step S1 uses an HCl solution with a mass fraction concentration of 30 - 60%.

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