Electroplating process for nickel-tungsten-phosphorus plating layer

Abstract

The invention relates to the technical field of electroplating, and particularly discloses a nickel-tungsten-phosphorus plating layer electroplating process which comprises the following steps: S1, preparing a nano composite electroplating solution which comprises nickel salt, tungstate, hypophosphite, nano silicon carbide powder, ZIF-67 (at) MXene core-shell nanosheets, a composite complexing agent and water; s2, plasma mixed gas is adopted for conducting etching treatment on the surface of the workpiece to be plated; s3, electroplating the to-be-electroplated workpiece subjected to surface treatment under the action of pulse current and an alternating magnetic field, and performing ultrasonic stirring on the composite electroplating liquid in the electroplating process; and S4, under nitrogen protection, the workpiece is subjected to annealing treatment. According to the electroplating process, through the synergistic effect of the nano SiC and the ZIF-67 (at) MXene, the component uniformity and the structural compactness of the nickel-tungsten-phosphorus coating can be effectively improved, and then the corrosion resistance of the nickel-tungsten-phosphorus coating in the complex oil gas environment is effectively improved.

Description

Technical Field

[0001] This application relates to the field of electroplating technology, and more specifically, it relates to a nickel-tungsten-phosphorus coating electroplating process. Background Art

[0002] In the field of the petroleum industry, the electroplating process, as the core means to improve the surface performance of petroleum machinery and equipment and accessories, is crucial for ensuring the stable operation of equipment in harsh environments. During oil extraction operations, mechanical equipment is exposed to a complex environment of high temperature, high pressure, high salinity, and corrosive media rich in hydrogen sulfide, carbon dioxide, etc. At the same time, it also needs to withstand dynamic loads such as mechanical vibration and fluid erosion during the drilling process. In this context, by electroplating a nickel-based alloy coating on the surface of the equipment through the electroplating process, the corrosion resistance, wear resistance, and mechanical properties of the substrate can be effectively improved, which is the key technical approach to extend the service life of the equipment and reduce maintenance costs.

[0003] Currently, the nickel-tungsten-phosphorus coatings used for the anti-corrosion of petroleum machinery and equipment are mainly prepared by traditional electroplating or electroless plating processes. The traditional electroplating process is to make nickel ions, tungsten ions, and phosphate ions in the plating solution undergo a reduction reaction on the surface of the substrate under the action of a direct current electric field to form a coating. Electroless plating is to use an oxidation-reduction reaction to make metal ions autocatalytically deposit on the catalytic surface without an external current. The nickel-tungsten-phosphorus coatings prepared by these processes can meet the anti-corrosion requirements of petroleum machinery and equipment to a certain extent. They have a relatively dense structure, can play a protective role in a conventional corrosion environment, and the preparation process is relatively simple, with controllable costs, and has been widely used in the petroleum industry. However, the existing nickel-tungsten-phosphorus coatings and electroplating processes still have many defects. On the one hand, the coatings prepared by traditional processes have deficiencies in composition uniformity, and the distribution of tungsten and phosphorus elements is not uniform enough, resulting in large differences in the local corrosion resistance of the coatings. Especially in the complex environments of high temperature, high pressure, high salinity, and corrosive gases such as hydrogen sulfide and carbon dioxide during oil extraction, the coatings are prone to local corrosion perforation, which in turn leads to substrate corrosion. On the other hand, the existing processes have limited ability to regulate the microstructure of the coatings, and the porosity of the coatings is relatively high, unable to effectively block the penetration of corrosive media. Therefore, how to improve the composition uniformity and structural compactness of nickel-tungsten-phosphorus coatings, thereby enhancing their corrosion resistance in complex petroleum environments, is a technical problem that needs to be solved urgently at present. Summary of the Invention

[0004] In order to improve the corrosion resistance of nickel-tungsten-phosphorus coatings in complex oil and gas environments, this application provides a nickel-tungsten-phosphorus coating electroplating process.

[0005] A nickel-tungsten-phosphorus coating electroplating process provided by this application adopts the following technical solution: A nickel-tungsten-phosphorus coating electroplating process includes the following steps: S1. Prepare a nano-composite electroplating solution, where the composite electroplating solution contains nickel salt, tungstate, hypophosphite, nano silicon carbide powder, ZIF-67@MXene core-shell nanosheets, a composite complexing agent, and water; S2. Use a plasma mixed gas to etch the surface of the workpiece to be plated. The etching pressure is 50 - 100 Pa, and the treatment time is 15 - 20 min; S3. Control the electroplating solution temperature at 65 - 70 °C, and electroplate the surface-treated workpiece to be plated under the action of pulsed current and alternating magnetic field. The frequency of the pulsed current is 1 - 5 kHz, the duty cycle is 20% - 40%, the average current density is 3 - 5 A / dm², the alternating magnetic field intensity is 0.5 - 2 T, and the frequency is 50 - 200 Hz. During the electroplating process, ultrasonic stirring is performed on the composite electroplating solution; S4. Anneal the workpiece under nitrogen protection.

[0006] By adopting the above technical solution, etching is carried out with a plasma mixed gas, which can increase the effective specific surface area of the workpiece to be plated, thereby facilitating the improvement of the bonding force between the coating and the workpiece to be plated. Through the above composite electroplating solution, nickel salt, tungstate, and hypophosphite provide the main sources of nickel, tungsten, and phosphorus. Through the coordination of the composite complexing agent (glycine + hydroxyethylidene diphosphonic acid), metal ions exist in the form of stable complex ions, avoiding uneven deposition rates caused by concentration fluctuations, thereby reducing the non-uniformity of the components in the coating. The ZIF-67@MXene core-shell nanosheets provide catalytic active sites to promote the co-deposition of tungsten and phosphorus, thereby improving the component uniformity and structural compactness of the coating. Nano silicon carbide powder, as a nano-particle reinforcement phase, refines the grains and fills the pores, further improving the structural compactness. Nano SiC and ZIF-67@MXene jointly refine the grains through "particle filling + layer stacking". The composite complexing agent and pulsed current synergistically control the ion deposition rate. During the electroplating process, dendritic growth is inhibited by the pulsed current, and the Lorentz force generated by the alternating magnetic field promotes ion migration, further reducing the porosity of the coating. Finally, a coating with "uniform composition and dense structure" is formed, enabling the coating to exhibit excellent corrosion resistance in complex petroleum environments.

[0007] Optionally, the ZIF-67@MXene core-shell nanosheets are prepared by the following method: A. Add Ti3AlC2 powder to the HF solution, stir at 30 - 40 °C for 20 - 24 h, then perform ultrasonic treatment, and then perform centrifugal separation to obtain a monolayer MXene dispersion. Add thiourea to the monolayer MXene dispersion and react at 100 - 120 °C for 10 - 12 h to obtain a thiolated monolayer MXene dispersion; B. Add the 2-methylimidazole solution to the cobalt nitrate solution, stir at room temperature for 30 - 60 min, then perform centrifugal separation, collect the precipitate, wash it with methanol, and dry it to obtain ZIF-67 nanoparticles; C. Mix the ZIF-67 nanoparticles and the thiolated monolayer MXene dispersion, ultrasonically disperse for 30 - 60 min, then stir and react at room temperature for 10 - 12 h, then perform centrifugal separation, wash the solid, dry it, heat the solid to 550 - 600 °C in a nitrogen atmosphere and hold for 2 - 3 h, and cool to obtain ZIF-67@MXene core-shell nanosheets.

[0008] By adopting the above technical solution, in the prepared ZIF-67@MXene core-shell nanosheets, the ZIF-67 inner core forms a porous carbon framework and cobalt-based nanoparticles after thermal decomposition. The porous structure can adsorb metal ions and promote their uniform release; the cobalt particles act as catalytic sites to enhance the co-deposition uniformity of nickel tungsten phosphorus. The thiolated MXene shell has excellent conductivity, can conduct current uniformly, and avoid uneven deposition of metal ions caused by too high local current density. The thiol groups guide the metal ions to deposit orderly on the surface of the nanosheets through the "molecular bridge" effect, forming an alloy coating with uniform composition.

[0009] Optionally, in step A, the mass concentration of the HF solution is 8% - 10%; the mass ratio of the Ti3AlC2 powder to the HF solution is 1:(15 - 20).

[0010] By adopting the above technical solution, the HF solution concentration and the ratio of Ti3AlC2 to HF can accurately control the MXene layer exfoliation effect, ensure that the monolayer rate meets the requirements, and thus is beneficial to improving the structural stability of the ZIF-67@MXene core-shell nanosheets.

[0011] Optionally, in step A, the addition amount of thiourea is 0.5% - 0.8% of the mass of the monolayer MXene dispersion.

[0012] Optionally, in step B, the mass concentration of the 2-methylimidazole solution is 0.4 - 0.6 mol / L; the mass concentration of the cobalt nitrate solution is 0.08 - 0.12 mol / L; the mass ratio of the 2-methylimidazole solution to the cobalt nitrate solution is (4 - 5):1.

[0013] Optionally, in step C, the mass ratio of the ZIF-67 nanoparticles to the thiolated monolayer MXene dispersion is 1:(2 - 4).

[0014] Optionally, the plasma mixed gas is Ar, O2 and CF4 with a volume ratio of 7:2:1.

[0015] By adopting the above technical solutions, Ar physical sputtering forms regular array grooves, providing mechanical locking sites and enhancing the mechanical bonding force between the coating and the substrate; O2 removes surface impurities through oxidation, improving the chemical bonding force between the coating and the substrate; CF4 introduces F⁻, selectively etches the metal surface, reduces the surface energy, promotes the infiltration of the plating solution, and reduces pinhole defects. The synergistic effect of the three gases can effectively increase the effective specific surface area of the workpiece to be plated, improve the bonding force between the coating and the workpiece to be plated, and make the coating adhere more firmly to the surface of the workpiece. This helps to improve the corrosion resistance and stability of the coating in complex environments.

[0016] Optionally, in S3, during the electroplating process, the parameters of the pulsed current and the alternating magnetic field are adjusted as follows: In the initial stage of electroplating within 0 - 30 min: Apply a pulsed current of 1 kHz, duty cycle of 30%, average current density of 3 A / dm², alternating magnetic field intensity of 1.2 T, and frequency of 50 Hz to form a nanocrystalline transition layer; In the middle stage of electroplating within 31 - 60 min: Apply a pulsed current of 3 kHz, duty cycle of 20%, average current density of 4 A / dm², alternating magnetic field intensity of 0.5 T, and frequency of 100 Hz to form an amorphous / nanocrystalline composite layer; In the later stage of electroplating within 61 - 90 min: Apply a pulsed current of 5 kHz, duty cycle of 40%, average current density of 5 A / dm², alternating magnetic field intensity of 2 T, and frequency of 200 Hz to form a gradient nanocrystalline surface layer from the amorphous / nanocrystalline composite layer.

[0017] By adopting the above technical solutions, during the electroplating process, by setting the parameters of the pulsed current and the alternating magnetic field as above, the double effects of suppressing dendrites by the pulsed current and promoting ion migration by the magnetic field can effectively reduce the porosity of the coating, thus forming a dense coating structure of "no holes and no cracks". Therefore, it shows excellent corrosion resistance in complex petroleum environments.

[0018] Optionally, the composite complexing agent includes glycine and hydroxyethylidene diphosphonic acid with a mass ratio of 1:1.

[0019] By adopting the above technical solutions, the composite complexing agent composed of glycine and hydroxyethylidene diphosphonic acid with a mass ratio of 1:1 can fully exert their synergistic effect. Glycine and hydroxyethylidene diphosphonic acid form stable complexes with metal ions, control the release rate of metal ions, avoid uneven deposition rates caused by concentration fluctuations, and thus reduce the non-uniformity of the components in the coating. The stable complexing effect helps to obtain a coating with uniform composition and dense structure, improve the quality and performance of the coating, and make the coating have better corrosion resistance and stability in complex environments.

[0020] Optionally, the specific formulation of the electroplating solution is as follows: Nickel sulfate 25 - 35 parts; 30 - 40 parts of sodium tungstate; 20 - 30 parts of sodium hypophosphite; 0.5 - 2 parts of nano silicon carbide powder; 1.5 - 3 parts of ZIF-67@MXene core-shell nanosheets; 0.5 - 1 part of composite complexing agent; The balance is 900 - 920 parts of water.

[0021] In summary, the present application has the following beneficial effects: 1. Since the present application introduces ZIF-67@MXene core-shell nanosheets into the electroplating solution formula, after the thermal decomposition of its inner core ZIF-67, a porous carbon skeleton and cobalt-based nanoparticles are formed. The porous structure can adsorb metal ions and promote their uniform release; the cobalt particles serve as catalytic sites to enhance the co-deposition uniformity of nickel-tungsten-phosphorus. At the same time, the thiolated MXene shell has excellent conductivity and can conduct current uniformly, avoiding uneven deposition of metal ions caused by too high local current density. The thiol groups guide the orderly deposition of metal ions on the surface of the nanosheets through the "molecular bridge" effect. In addition, the coordination effect of the composite complexing agent (glycine + hydroxyethylidene diphosphonic acid) makes the metal ions exist in the form of stable complex ions, avoiding uneven deposition rates caused by concentration fluctuations, thereby reducing the inhomogeneity of the components in the coating. The combined action of these factors makes the distribution of elements such as nickel, tungsten, and phosphorus in the coating more uniform, avoiding the problem of large differences in local corrosion resistance. In a complex petroleum environment, the overall coating can better resist corrosion and improve its corrosion resistance.

[0022] 2. The electroplating process of the present application is excellent in improving the compactness of the coating structure. The nano silicon carbide powder, as a nano-particle reinforcement phase, refines the grains and fills the pores, further improving the structural compactness. Nano-SiC and ZIF-67@MXene jointly refine the grains through "particle filling + layer stacking". During the electroplating process, the pulsed current and the alternating magnetic field act synergistically. The pulsed current inhibits the growth of dendrites, and the alternating magnetic field generates Lorentz force to promote ion migration, further reducing the porosity of the coating. Moreover, at different stages of electroplating, by precisely regulating the parameters of the pulsed current and the alternating magnetic field, such as forming a nano-crystalline transition layer in the initial stage of electroplating, an amorphous / nano-crystalline composite layer in the middle stage, and a gradient nano-crystalline surface layer in the later stage, the microstructure of the coating is further optimized, forming a dense coating structure of "no holes and no cracks". This dense structure can effectively block the penetration of corrosive media, making the coating show excellent corrosion resistance in a complex petroleum environment.

[0023] 3. The electroplating process of the present application comprehensively improves the corrosion resistance of the coating in a complex petroleum environment by enhancing the uniformity of the coating composition and the density of the structure. The plasma mixed gas etching treatment increases the effective specific surface area of the workpiece to be plated, improves the bonding force between the coating and the workpiece to be plated, and enables the coating to adhere more firmly to the surface of the workpiece. During the electroplating process, by means of the coordinated control of the ion deposition rate by the composite complexing agent and the pulsed current, and the promotion of ion migration by the alternating magnetic field, a coating with uniform composition and dense structure is formed. When facing the environment of high temperature, high pressure, high salinity and rich in corrosive media such as hydrogen sulfide and carbon dioxide during oil extraction operations, this coating can effectively resist the erosion of corrosive media and avoid the occurrence of local corrosion perforation and matrix corrosion. Compared with the traditional nickel-tungsten-phosphorus coating and electroplating process, the coating of the present application has better corrosion resistance and stability in a complex petroleum environment, provides a strong guarantee for the long-term stable operation of oil machinery and equipment, and reduces the maintenance cost. Detailed implementation manners

[0024] The following further elaborates on the present application in conjunction with embodiments.

[0025] Preparation example of ZIF-67@MXene core-shell nanosheets Preparation example 1 The ZIF-67@MXene core-shell nanosheets are prepared by the following method: A. Add 1 kg of Ti3AlC2 powder to 15 kg of an HF solution with a mass concentration of 8%, stir at 30 °C for 20 h, then perform ultrasonic treatment at a power of 300 w for 3 h, and then centrifuge at 3000 rmp to collect the supernatant to obtain a monolayer MXene dispersion. Add 50 g of thiourea to 10 kg of the monolayer MXene dispersion and react at 100 °C for 10 h to obtain a thiolated monolayer MXene dispersion. B. Add 4 kg of a 2-methylimidazole solution with a concentration of 0.4 mol / L to 1 kg of a cobalt nitrate solution with a concentration of 0.08 mol / L, stir at 5000 rmp for 30 min, then perform centrifugation to collect the precipitate, wash it with methanol, and dry it to obtain ZIF-67 nanoparticles. C. Mix 1 kg of ZIF-67 nanoparticles and 2 kg of the thiolated monolayer MXene dispersion, ultrasonically disperse for 30 min, then stir and react at room temperature for 10 h, then perform centrifugation, wash the solid, dry it, heat the solid to 550 °C in a nitrogen atmosphere and hold for 2 h, and cool to obtain ZIF-67@MXene core-shell nanosheets.

[0026] Preparation example 2 The ZIF-67@MXene core-shell nanosheets are prepared by the following method: A. Add 1 kg of Ti3AlC2 powder to 18 kg of HF solution with a mass concentration of 9%, stir at 35 °C for 22 h, then ultrasonically treat at a power of 300 w for 3 h, and then centrifuge at 3000 rmp. Collect the supernatant to obtain a monolayer MXene dispersion. Add 65 g of thiourea to 10 kg of the monolayer MXene dispersion and react at 110 °C for 11 h to obtain a thiolated monolayer MXene dispersion; B. Add 4.5 kg of 2-methylimidazole solution with a concentration of 0.5 mol / L to 1 kg of cobalt nitrate solution with a concentration of 0.10 mol / L, stir at 5000 rmp for 30 min, then centrifuge, collect the precipitate, wash with methanol, and dry to obtain ZIF-67 nanoparticles; C. Mix 1 kg of ZIF-67 nanoparticles and 3 kg of the thiolated monolayer MXene dispersion, ultrasonically disperse for 40 min, then stir and react at room temperature for 11 h, then centrifuge, wash the solid, dry, heat the solid to 580 °C in a nitrogen atmosphere and hold for 2.5 h, and cool to obtain ZIF-67@MXene core-shell nanosheets.

[0027] Preparation Example 3 ZIF-67@MXene core-shell nanosheets are prepared by the following method: A. Add 1 kg of Ti3AlC2 powder to 20 kg of HF solution with a mass concentration of 10%, stir at 40 °C for 24 h, then ultrasonically treat at a power of 300 w for 3 h, and then centrifuge at 3000 rmp. Collect the supernatant to obtain a monolayer MXene dispersion. Add 80 g of thiourea to 10 kg of the monolayer MXene dispersion and react at 120 °C for 12 h to obtain a thiolated monolayer MXene dispersion; B. Add 5 kg of 2-methylimidazole solution with a concentration of 0.6 mol / L to 1 kg of cobalt nitrate solution with a concentration of 0.12 mol / L, stir at 5000 rmp for 30 min, then centrifuge, collect the precipitate, wash with methanol, and dry to obtain ZIF-67 nanoparticles; C. Mix 1 kg of ZIF-67 nanoparticles and 4 kg of the thiolated monolayer MXene dispersion, ultrasonically disperse for 60 min, then stir and react at room temperature for 12 h, then centrifuge, wash the solid, dry, heat the solid to 600 °C in a nitrogen atmosphere and hold for 3 h, and cool to obtain ZIF-67@MXene core-shell nanosheets.

[0028] Example The workpiece to be plated used in the examples of this application is a 304 stainless steel oil well pipe with an outer diameter of 114.30 mm and a wall thickness of 9.50 mm.

[0029] Example 1 A nickel-tungsten-phosphorus plating process, comprising the following steps: S1. Weigh the raw materials according to the ratio shown in Table 1, and then mix the raw materials in Table 1 and stir for 5 min to obtain a composite electroplating solution. Among them, the ZIF-67@MXene core-shell nanosheets are selected from Preparation Example 1, and the composite complexing agent is glycine and hydroxyethylidene diphosphonic acid with a mass ratio of 1:1; S2. Use a plasma mixed gas to etch the surface of the workpiece to be plated. The plasma mixed gas is Ar, O2 and CF4 with a volume ratio of 7:2:1; the etching pressure is 50 Pa, and the treatment time is 20 min; S3. Adopt a three-electrode system. The working electrode is the workpiece after etching treatment, the reference electrode is a saturated calomel electrode, and the auxiliary anode is a reticulated platinum-titanium electrode. The temperature of the composite electroplating solution is maintained at 65 °C, and the circulation flow rate is 2.5 L / min. During the electroplating process, the composite electroplating solution is stirred at a frequency of 40 kHz. Under the action of pulsed current and alternating magnetic field, electroplate the workpiece to be plated after surface treatment. The parameter regulation of the pulsed current and alternating magnetic field during the electroplating process is as follows: In the initial stage of electroplating within 0 - 30 min: Apply a 1 kHz pulsed current, duty cycle 30%, average current density 3 A / dm², alternating magnetic field strength 1.2 T, frequency 50 Hz, to form a nanocrystalline transition layer; In the middle stage of electroplating within 31 - 60 min: Apply a 3 kHz pulsed current, duty cycle 20%, average current density 4 A / dm², alternating magnetic field strength 0.5 T, frequency 100 Hz, to form an amorphous / nanocrystalline composite layer; In the later stage of electroplating within 61 - 90 min: Apply a 5 kHz pulsed current, duty cycle 40%, average current density 5 A / dm², alternating magnetic field strength 2 T, frequency 200 Hz, to form a gradient nanocrystalline surface layer with an amorphous / nanocrystalline composite layer; S4. Place the electroplated workpiece in a quartz furnace, under nitrogen protection, heat it to 200 °C at a heating rate of 5 °C / min, and keep it warm for 30 min; then continue to heat it to 350 °C at a heating rate of 3 °C / min, and keep it warm for 60 min; then heat it to 450 °C at a heating rate of 2 °C / min, and keep it warm for 120 min, and then cool it naturally.

[0030] Example 2 A nickel-tungsten-phosphorus plating process, comprising the following steps: S1. Weigh the raw materials according to the ratio shown in Table 1, and then mix the raw materials in Table 1 and stir for 5 min to obtain a composite electroplating solution. Among them, the ZIF-67@MXene core-shell nanosheets are selected from Preparation Example 2, and the composite complexing agent is glycine and hydroxyethylidene diphosphonic acid with a mass ratio of 1:1; S2. Etch the surface of the workpiece to be plated with a plasma mixed gas, where the plasma mixed gas is Ar, O₂, and CF₄ with a volume ratio of 7:2:1; the etching pressure is 80 Pa, and the treatment time is 18 min; S3. Adopt a three - electrode system. The working electrode is the workpiece after etching treatment, the reference electrode is a saturated calomel electrode, and the auxiliary anode is a reticulated platinum - titanium electrode. The temperature of the composite plating solution is maintained at 68 °C, and the circulation flow rate is 2.5 L / min. During the electroplating process, the composite plating solution is stirred at a frequency of 40 kHz. Electroplate the surface - treated workpiece to be plated under the action of a pulsed current and an alternating magnetic field. The parameter regulation of the pulsed current and the alternating magnetic field during the electroplating process is as follows: In the initial stage of electroplating within 0 - 30 min: Apply a 1 kHz pulsed current, duty cycle 30%, average current density 3 A / dm², alternating magnetic field intensity 1.2 T, frequency 50 Hz to form a nanocrystalline transition layer; In the middle stage of electroplating within 31 - 60 min: Apply a 3 kHz pulsed current, duty cycle 20%, average current density 4 A / dm², alternating magnetic field intensity 0.5 T, frequency 100 Hz to form an amorphous / nanocrystalline composite layer; In the later stage of electroplating within 61 - 90 min: Apply a 5 kHz pulsed current, duty cycle 40%, average current density 5 A / dm², alternating magnetic field intensity 2 T, frequency 200 Hz to form a gradient nanocrystalline surface layer with an amorphous / nanocrystalline composite layer; S4. Place the electroplated workpiece in a quartz furnace. Under nitrogen protection, heat it to 200 °C at a heating rate of 5 °C / min and keep it warm for 30 min; then continue to heat it to 350 °C at a heating rate of 3 °C / min and keep it warm for 60 min; then heat it to 450 °C at a heating rate of 2 °C / min and keep it warm for 120 min, and then cool it naturally.

[0031] Example 3 A nickel - tungsten - phosphorus plating process, comprising the following steps: S1. Weigh the raw materials according to the ratio shown in Table 1, and then mix the raw materials in Table 1 and stir for 5 min to obtain a composite plating solution. Among them, the ZIF - 67@MXene core - shell nanosheets are selected from Preparation Example 3, and the composite complexing agent is glycine and hydroxyethylidene diphosphonic acid with a mass ratio of 1:1; S2. Etch the surface of the workpiece to be plated with a plasma mixed gas, where the plasma mixed gas is Ar, O₂, and CF₄ with a volume ratio of 7:2:1; the etching pressure is 100 Pa, and the treatment time is 15 min; S3. Adopt a three - electrode system. The working electrode is the workpiece after etching treatment, the reference electrode is a saturated calomel electrode, and the auxiliary anode is a reticulated platinum - titanium electrode. The temperature of the composite electroplating solution is maintained at 70 °C, and the circulation flow rate is 2.5 L / min. During the electroplating process, the composite electroplating solution is stirred at a frequency of 40 kHz. Under the action of pulsed current and alternating magnetic field, electroplating is carried out on the workpiece to be plated after surface treatment. The parameter regulation of pulsed current and alternating magnetic field during the electroplating process is as follows: In the initial stage of electroplating (0 - 30 min): Apply a pulsed current of 1 kHz, duty cycle 30%, average current density 3 A / dm², alternating magnetic field intensity 1.2 T, and frequency 50 Hz to form a nanocrystalline transition layer; In the middle stage of electroplating (31 - 60 min): Apply a pulsed current of 3 kHz, duty cycle 20%, average current density 4 A / dm², alternating magnetic field intensity 0.5 T, and frequency 100 Hz to form an amorphous / nanocrystalline composite layer; In the later stage of electroplating (61 - 90 min): Apply a pulsed current of 5 kHz, duty cycle 40%, average current density 5 A / dm², alternating magnetic field intensity 2 T, and frequency 200 Hz to form a gradient nanocrystalline surface layer; S4. Place the electroplated workpiece in a quartz furnace. Under nitrogen protection, heat it to 200 °C at a heating rate of 5 °C / min and hold for 30 min; then continue to heat to 350 °C at a heating rate of 3 °C / min and hold for 60 min; then heat to 450 °C at a heating rate of 2 °C / min and hold for 120 min, and then cool it naturally.

[0032] Table 1 Raw material components and ratios (g) of the composite electroplating solution in Examples 1 - 3

[0033] Example 4 A nickel - tungsten - phosphorus coating electroplating process, different from Example 1 in that: the plasma mixed gas in S2 is Ar, O2 and CF4 with a volume ratio of 4:4:2.

[0034] Example 5 A nickel-tungsten-phosphorus plating process, which is different from that of Example 1 in that: in S3, the parameters of the pulsed current and the alternating magnetic field during the electroplating process are adjusted as follows: within 0-30 minutes at the initial stage of electroplating: apply a pulsed current of 5 kHz, a duty cycle of 30%, an average current density of 5 A / dm², an alternating magnetic field strength of 0.5 T, and a frequency of 50 Hz to form a nanocrystalline transition layer; within 31-60 minutes at the middle stage of electroplating: apply a pulsed current of 3 kHz, a duty cycle of 20%, an average current density of 4 A / dm², an alternating magnetic field strength of 1.0 T, and a frequency of 100 Hz to form an amorphous / nanocrystalline composite layer; within 61-90 minutes at the later stage of electroplating: apply a pulsed current of 1 kHz, a duty cycle of 40%, an average current density of 3 A / dm², an alternating magnetic field strength of 2 T, and a frequency of 200 Hz to form a gradient nanocrystalline surface layer.

[0035] Comparative example Comparative example 1 A nickel-tungsten-phosphorus plating process, which is different from that of Example 1 in that: in S1 of this comparative example, ZIF-67@MXene core-shell nanosheets are not added to the composite electroplating solution, and the difference is made up with water.

[0036] Comparative example 2 A nickel-tungsten-phosphorus plating process, which is different from that of Example 1 in that: in S1 of this comparative example, nano silicon carbide powder is not added to the composite electroplating solution, and the difference is made up with water.

[0037] Comparative example 3 A nickel-tungsten-phosphorus plating process, which is different from that of Example 1 in that: in this comparative example, step S2 is not carried out, that is, the workpiece to be plated is not etched, and in S3, the unetched workpiece to be plated is directly used for electroplating.

[0038] Comparative example 4 A nickel-tungsten-phosphorus plating process, which is different from that of Example 1 in that: in S3 of this comparative example, no alternating magnetic field is set.

[0039] Performance detection test Test samples: Workpieces after electroplating in Examples 1-5 and Comparative Examples 1-4.

[0040] 1. Adhesion strength Referring to the standard of "ASTM D4541", a vertical tensile force is applied to the workpiece until the coating is peeled off, and the maximum tensile force at the time of peeling is measured to evaluate the adhesion strength.

[0041] 2. Porosity The workpiece is placed in a sodium chloride solution with a concentration of 5%, left standing at 30 °C for 48 h, the sample is taken out, the surface is rinsed with clean water, and after drying, it is observed under a microscope, and the number of corrosion points with a diameter ≥ 0.1 mm is recorded.

[0042] 3. Corrosion resistance Simulate the high-temperature, high-pressure, and co-existing environment of H2S / CO2 in oil exploitation. Use 3.5% NaCl solution as the medium to simulate high salinity, introduce H2S (partial pressure 0.1 MPa) and CO2 (partial pressure 0.5 MPa), and adjust the pH to 5.5. The temperature of the medium system is 120 °C, and the pressure is 10 MPa to simulate the downhole high pressure. Then place the specimen in an autoclave, introduce the medium, and raise the temperature and pressure to the set conditions, maintain for 720 h, take out the specimen, rinse it with deionized water, dry it and weigh it, and calculate the corrosion weight loss rate.

[0043] Table 2 Test results

[0044] The test data shows that Examples 1-3 perform excellently in various performance indicators due to the complete adoption of the process of this application. Their bonding strength reaches 84.5-86.7 MPa, which is significantly improved compared with the traditional process. This benefits from the synergistic enhancement of the bonding force between the coating and the substrate by ZIF-67@MXene core-shell nanosheets and plasma etching treatment; there are only 4-5 corrosion points per dm², and the corrosion weight loss rate is as low as 0.32%-0.36%, verifying the key role of nano-silicon carbide, composite complexing agent, and pulsed current-alternating magnetic field regulation in improving the composition uniformity and structural compactness, effectively blocking the penetration of corrosive media.

[0045] Through the comparison between Examples 4, 5 and Comparative Examples 1-4, the influence of the lack of process parameters and core materials on the performance can be clearly seen. After adjusting the plasma gas ratio in Example 4, the bonding strength drops to 75.2 MPa, and the corrosion weight loss rate rises to 0.81%, indicating that the imbalance of gas ratio will damage the surface uniformity; in Example 5, changing the pulsed current and magnetic field parameters results in insufficient optimization of the coating microstructure and reduced corrosion resistance. In Comparative Example 1, the core-shell nanosheets were not added, and the bonding strength dropped sharply to 48.8 MPa, and the corrosion weight loss rate reached 1.35%; in Comparative Example 2, nano-silicon carbide was lacking, and the number of corrosion points increased to 32 per dm², both of which confirmed the decisive role of key materials in the coating compactness and corrosion resistance.

[0046] This specific embodiment is only an explanation of this application, and it is not a limitation of this application. Those skilled in the art can make modifications without creative contributions to this embodiment 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. A nickel-tungsten-phosphorus plating process, characterized in that, It includes the following steps: S1. Prepare a nano-composite electroplating solution, which contains nickel salt, tungstate, hypophosphite, nano-silicon carbide powder, ZIF-67@MXene core-shell nanosheets, a composite complexing agent and water; S2. Use a plasma mixed gas to etch the surface of the workpiece to be plated, with an etching pressure of 50 - 100 Pa and a treatment time of 15 - 20 min; S3. Control the electroplating solution temperature at 65 - 70 °C, and electroplate the surface-treated workpiece to be plated under the action of a pulsed current and an alternating magnetic field. The frequency of the pulsed current is 1 - 5 kHz, the duty cycle is 20% - 40%, the average current density is 3 - 5 A / dm², the alternating magnetic field intensity is 0.5 - 2 T, and the frequency is 50 - 200 Hz. During the electroplating process, ultrasonic stirring is carried out on the composite electroplating solution; S4. Under nitrogen protection, anneal the workpiece.

2. A nickel-tungsten-phosphorus plating process according to claim 1, characterized in that: The ZIF-67@MXene core-shell nanosheets are prepared by the following method: A. Add Ti3AlC2 powder to an HF solution, stir at 30 - 40 °C for 20 - 24 h, then carry out ultrasonic treatment, and then carry out centrifugal separation to obtain a monolayer MXene dispersion. Add thiourea to the monolayer MXene dispersion and react to obtain a mercapto-functionalized monolayer MXene dispersion; B. Add a 2-methylimidazole solution to a cobalt nitrate solution, stir at room temperature for 30 - 60 min, then carry out centrifugal separation, collect the precipitate, wash with methanol, and dry to obtain ZIF-67 nanoparticles; C. Mix the ZIF-67 nanoparticles and the mercapto-functionalized monolayer MXene dispersion, stir for 10 - 12 h after ultrasonic treatment, then carry out centrifugal separation, wash and dry the solid, heat the solid to 550 - 600 °C in a nitrogen atmosphere and keep it warm for 2 - 3 h, and cool to obtain ZIF-67@MXene core-shell nanosheets.

3. A nickel-tungsten-phosphorus plating process according to claim 2, characterized in that: In step A, the mass concentration of the HF solution is 8% - 10%; the mass ratio of the Ti3AlC2 powder to the HF solution is 1:(15 - 20).

4. A nickel-tungsten-phosphorus plating process according to claim 3, characterized in that: In step A, the addition amount of thiourea is 0.5% - 0.8% of the mass of the monolayer MXene dispersion.

5. A nickel-tungsten-phosphorus plating process according to claim 4, characterized in that: In step B, the mass concentration of the 2-methylimidazole solution is 0.4 - 0.6 mol / L; the mass concentration of the cobalt nitrate solution is 0.08 - 0.12 mol / L; the mass ratio of the 2-methylimidazole solution to the cobalt nitrate solution is (4 - 5):

1.

6. A nickel-tungsten-phosphorus plating process according to claim 5, characterized in that: In step C, the mass ratio of the ZIF-67 nanoparticles to the mercapto-functionalized monolayer MXene dispersion is 1:(2 - 4).

7. A nickel-tungsten-phosphorus plating process according to claim 1, characterized in that: The plasma mixed gas is Ar, O2 and CF4 with a volume ratio of 7:2:

1.

8. A nickel-tungsten-phosphorus plating process according to claim 1, characterized in that: In S3, the parameter regulation of the pulsed current and the alternating magnetic field during the electroplating process is as follows: Within the initial 0 - 30 min of electroplating: Apply a 1 kHz pulsed current, with a duty cycle of 30%, an average current density of 3 A / dm², an alternating magnetic field intensity of 1.2 T, and a frequency of 50 Hz to form a nano-crystalline transition layer; During the middle stage of electroplating (31 - 60 min): Apply a pulsed current of 3 kHz, duty cycle of 20%, average current density of 4 A / dm², alternating magnetic field intensity of 0.5 T, and frequency of 100 Hz to form an amorphous / nanocrystalline composite layer; During the later stage of electroplating (61 - 90 min): Apply a pulsed current of 5 kHz, duty cycle of 40%, average current density of 5 A / dm², alternating magnetic field intensity of 2 T, and frequency of 200 Hz to form a gradient nanocrystalline surface layer on the amorphous / nanocrystalline composite layer.

9. A nickel-tungsten-phosphorus plating process according to claim 1, characterized in that: The composite complexing agent includes glycine and hydroxyethylidene diphosphonic acid with a mass ratio of 1:

1.

10. A nickel-tungsten-phosphorus plating process according to claim 1, characterized in that: The specific formulation of the electroplating solution is as follows: 25 - 35 parts of nickel sulfate; 30 - 40 parts of sodium tungstate; 20 - 30 parts of sodium hypophosphite; 0.5 - 2 parts of nano silicon carbide powder; 1.5 - 3 parts of ZIF-67@MXene core-shell nanosheets; 0.5 - 1 part of composite complexing agent; The balance is 900 - 920 parts of water.

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