Highly wear resistant electroplated ni-co-al2o3 coating and method of making same

Abstract

This invention designs a high-wear-resistant electroplated Ni-Co-Al2O3 coating and its preparation method. An aminosulfonate electrolyte system is used as the electrolyte system, and an ultrasonic-assisted DC electroplating method is employed to prepare the Ni-Co-Al2O3 composite coating. The coating preparation steps mainly include substrate pretreatment, electrolyte component proportioning, electrolyte treatment, and electroplating coating preparation. In this invention, to promote the uniform dispersion of nano-Al2O3, sodium dodecylbenzenesulfonate (SDBS) is added as a dispersant. After ionization, it adsorbs onto the surface of nano-Al2O3, forming a negatively charged layer, effectively reducing Al2O3 agglomeration, thereby obtaining an electroplated layer with high dispersibility, high density, and high wear resistance. The prepared coating has a uniform and dense structure, with an average grain size of 95~172 nm, a nano-Al2O3 agglomerate size not exceeding 132 nm, and a hardness of 353~452 HV. 0.1 The wear rate is 3.21 × 10⁻⁶. ‑8 ~4.34×10 ‑8 mm 3 / (N·m), exhibiting high wear resistance.

Description

Technical Field

[0001] This invention belongs to the field of nickel-based composite material coatings, and relates to a highly wear-resistant coating with a nanocrystalline Ni-Co alloy matrix reinforced by highly dispersed nano-Al2O3 and its electroplating method. Technical Background

[0002] Metal parts, due to long-term exposure to the service environment, are prone to wear and corrosion, leading to cracking and failure. Surface coating technology, by creating a protective layer on the metal surface, improves the service strength and lifespan of metal parts, significantly reducing application costs and service risks. Electroplating, as one of the mainstream surface coating technologies, has advantages such as low cost, simple operation, high efficiency, no limitation on the shape of the substrate material, and low thermal impact on the substrate. Among them, electroplated Ni-Co coatings exhibit excellent wear resistance and corrosion resistance. This is attributed to the nanocrystalline structure and uniform, dense microstructure of the Ni-based electroplated layer after deposition, as well as its ability to rapidly form a dense and stable passivation film in corrosive environments. Simultaneously, the addition of Co reduces the stacking fault energy of the coating, enhancing its wear resistance. Therefore, Ni-Co coatings are widely used in aerospace, machining, and industrial production, among other fields.

[0003] However, with the advancement of technology, the service environment of metal parts is becoming increasingly harsh. The insufficient wear resistance of Ni-Co coatings limits their application in various industries. Nanocomposite electroplating is a method that introduces second-phase nanoparticles into the electroplating process, thereby reducing the porosity of the coating and increasing its hardness and wear resistance. Nano Al2O3, as a nanoparticle with high hardness, high chemical stability, and low cost, is one of the preferred choices for industrial production of composite coatings. However, due to the high surface activity of nano Al2O3 itself, excessive addition will form agglomerates in the electrolyte, causing the coating porosity to increase rather than decrease, thus deteriorating the coating's various properties. Sodium dodecylbenzenesulfonate (SDBS) is an ionic dispersant commonly used in water and refrigerants to disperse nano Al2O3, which can significantly reduce its agglomeration in solution. This invention aims to obtain a Ni-Co-Al2O3 composite coating with excellent wear resistance by controlling the addition amount of nano Al2O3 and SDBS and using an ultrasonic-assisted DC electroplating method, which has very important application prospects. Summary of the Invention

[0004] This invention aims to develop a high-wear-resistant electroplated Ni-Co-Al2O3 coating and its preparation method. The electrolyte composition and dosage are as follows: Ni(NH2SO3)2·4H2O 70~90 g / L; Co(NH2SO3)2·4H2O 4~10 g / L; H3BO3 35~50 g / L; NiCl2·6H2O 6.0~7.5 g / L; C7H5O3NS 3~5 g / L; nano-α-Al2O3 2~3 g / L with a particle size of 30~50 nm; sodium dodecylbenzenesulfonate 0.8~1.2 g / L. The coating is prepared by ultrasonic-assisted direct current electroplating. The average grain size of the Ni-Co matrix metal in the coating is 95~172 nm; the agglomerate size of the nano-Al2O3 is no greater than 132 nm; and the hardness is 353~452 HV. 0.1 The wear rate was 3.21 × 10⁻⁶. -8 ~4.34×10 -8 mm 3 / (N·m); It has the characteristics of high Al2O3 dispersibility, high density and high wear resistance.

[0005] The electroplating coating preparation method of the present invention includes the following steps:

[0006] (1) Substrate Pretreatment: Surface pretreatment of the electroplated substrate is a crucial step in ensuring the adhesion, uniformity, and durability of the plating layer. Its core objectives are to remove contaminants, expose the fresh metal surface, and achieve microscopic smoothing. The main pretreatment methods include mechanical methods (sandblasting / shot peening, polishing / grinding, tumbling), chemical methods (alkaline cleaning, organic solvent cleaning, emulsion degreasing, pickling, electrolytic etching), electrochemical methods (electrolytic degreasing, electrolytic pickling), activation and surface conditioning (activation, surface conditioning), cleaning, and drying. Specific pretreatment methods depend on the type of substrate. The substrate alloys used in this invention include Cu alloys, Al alloys, Mg alloys, Ti alloys, stainless steel, low-carbon steel, alloy steel, or high-temperature alloys.

[0007] (2) Electrolyte preparation: Prepare Ni(NH2SO3)2·4H2O, Co(NH2SO3)2·4H2O, NiCl2·6H2O, C7H5O3NS, nano-Al2O3, and sodium dodecylbenzenesulfonate according to the required proportions. After weighing, pour them into the electrolytic cell. Add the corresponding volume of deionized water.

[0008] (3) Electrolyte ultrasonic dispersion treatment: Heat the prepared electrolyte to 48~52 ºC; add H3BO3 to adjust the pH of the solution to 4.5~5.0; ultrasonically disperse the electrolyte to make the nano Al2O3 uniformly dispersed.

[0009] (4) Electroplating coating preparation: Connect the substrate alloy to the cathode of the DC power supply; connect the Ni plate to the anode to replenish Ni ions during electroplating; turn on the power supply to start electroplating, and adjust the DC power supply current to 2.5~3.5 A / dm. 2 The electroplating process involves adding Co(NH2SO3)2·4H2O solution to replenish Co ions and maintaining the electrolyte temperature and pH value stable. After obtaining a coating of a certain thickness through electroplating, the power is turned off, the substrate alloy is removed, rinsed with deionized water, and dried with an air gun to obtain the electroplated coating.

[0010] For the above coating preparation, using Cu alloy as the substrate alloy and 5 L of electrolyte as an example, the specific details are as follows:

[0011] (1) Substrate pretreatment: The Cu alloy substrate was polished with 400#, 800# and 1200# sandpaper; the voltage was 4.5~5.5 V and the electrolyte was perchloric acid methanol solution with a volume ratio of HClO4:CH3OH=4:1 for 8~10 s; the substrate was immersed in 14.5~15.5 vol% HCl solution for 20~30 min to remove the surface oxide film; the substrate was immersed in 4.5~6.0 vol% H2SO4 solution for 20~40 s to activate the substrate; the substrate was rinsed with deionized water for 5~10 min to remove residual acid on the surface; and the substrate was dried with an air gun.

[0012] (2) Electrolyte preparation: Weigh 350-450 g of nickel sulfamate (Ni(NH2SO3)2·4H2O), 20-50 g of cobalt sulfamate (Co(NH2SO3)2·4H2O), 30-37.5 g of nickel chloride (NiCl2·6H2O), 15-25 g of saccharin (C7H5O3NS), 10-15 g of nano-Al2O3, and 4-6 g of sodium dodecylbenzenesulfonate (SDBS) using an electronic balance. Pour the weighed materials into the electrolytic cell. Add deionized water to the electrolytic cell to a volume of 5 L.

[0013] (3) Electrolyte ultrasonic dispersion treatment: Heat the electrolytic cell to 48~52 ºC; add H3BO3 and adjust the pH of the solution to 4.5~5.0; adjust the ultrasonic power to 350~400 W and ultrasonically disperse the electrolyte for 2~3 h to obtain a uniformly dispersed electrolyte of nano Al2O3.

[0014] (4) Electroplating coating preparation: Connect the substrate alloy to the cathode of the DC power supply; connect the Ni plate to the anode; turn on the power supply to start electroplating, and adjust the DC power supply current to 2.5~3.5 A / dm. 2The electroplating process involves adding Co(NH2SO3)2·4H2O solution to replenish Co ions, maintaining the electrolyte temperature at 48~52 ºC and the pH value at 4.5~5.0. After obtaining a coating of a certain thickness through electroplating, the power is turned off, the substrate alloy is removed, rinsed with deionized water, and dried with an air gun to obtain the electroplated coating.

[0015] In the above preparation, a Ni-Co-Al2O3 composite coating was prepared by ultrasonic-assisted DC electroplating, resulting in a dense structure with uniformly dispersed nano-Al2O3, achieving a hardness of 353~452 HV. 0.1 The wear rate is only 3.21×10. -8 ~4.34×10 -8 mm 3 / (N·m). It has the following advantages compared to existing Ni-Co electroplated coatings:

[0016] (1) The nano-Al2O3 in the composite coating is uniformly dispersed, and the agglomeration size of the nano-Al2O3 is no greater than 132 nm; it plays a role in grain refinement, and the average grain size of the Ni-Co matrix metal is 95~172 nm; thus giving the coating high hardness and excellent wear resistance.

[0017] (2) The nano-Al2O3 in the coating fills the pores and other defects in the coating, thereby reducing the porosity of the coating, increasing the density, and improving the hardness and wear resistance of the coating.

[0018] (3) The hardness of the composite coating reaches 353~452 HV. 0.1 The wear rate is only 3.21×10. -8 ~4.34×10 -8 mm 3 / (N·m), characterized by high hardness and high wear resistance.

[0019] (4) The electroplating method of the present invention has the advantages of simple and safe process preparation, simple equipment and low cost. Attached Figure Description

[0020] Figure 1 TEM bright-field image of Ni-Co-Al2O3 prepared in Example 1

[0021] Figure 2 This is a TEM image of nano-Al2O3 in the coating of Comparative Example 1.

[0022] Figure 3 SEM image of the coating after polishing in Example 2

[0023] Figure 4 This is a TEM image of nano-Al2O3 in the coating of Example 3.

[0024] Figure 5 Friction curve of the coating in Example 4 Detailed Implementation

[0025] Example 1

[0026] 1. Substrate pretreatment: The Cu alloy substrate was polished with 400#, 800#, and 1200# sandpaper; electropolishing was performed for 9 seconds using a 4.5 V voltage and a perchloric acid-methanol solution with a volume ratio of HClO4:CH3OH=4:1; the substrate was immersed in a 15.1 vol% HCl solution for 23 minutes to remove the surface oxide film; the substrate was then immersed in a 4.7 vol% H2SO4 solution for 25 seconds to activate it; the substrate was rinsed with deionized water for 5 minutes to remove residual acid; and finally dried with an air gun.

[0027] 2. Electrolyte preparation: Weigh out 360 g of Ni(NH2SO3)2·4H2O; 50 g of Co(NH2SO3)2·4H2O; 30 g of nickel chloride NiCl2·6H2O; 22 g of saccharin C7H5O3NS; 15 g of nano-Al2O3; and 5 g of sodium dodecylbenzenesulfonate SDBS. Pour the weighed materials into the electrolytic cell. Add deionized water to the electrolytic cell to a volume of 5 L.

[0028] 3. Electrolyte ultrasonic dispersion treatment: Heat the electrolytic cell to 48 ºC; add H3BO3 to adjust the pH of the solution to 4.8; adjust the ultrasonic power to 360 W and ultrasonically disperse for 2 h to obtain an electrolyte with uniformly dispersed nano-Al2O3.

[0029] 4. Electroplating Coating Preparation: Connect the substrate alloy to the cathode of the DC power supply; connect the Ni plate to the anode; turn on the power to start electroplating, and adjust the DC power supply current to 3.2 A / dm. 2 Maintain the electrolyte temperature at 48 ºC and the pH value at 4.8; after electroplating for 1.5 h, turn off the power, remove the Cu alloy plate with Ni-Co-Al2O3 coating, rinse with deionized water, and blow dry with an air gun to obtain the electroplated coating.

[0030] Figure 1 The image shows a TEM image of the Ni-Co-Al2O3 composite coating prepared using the above method. As shown, the coating exhibits uniform grain size with no coarse grains. According to software analysis, the coating is uniform and dense, with an average matrix grain size of 95 nm. The nano-Al2O3 within the coating is well dispersed, with agglomerates no larger than 92 nm. The coating hardness is 452 HV. 0.1 After friction testing with GCr15 steel balls, the average coefficient of friction of the coating was 0.55. Based on volumetric wear rate calculations, the wear rate of this coating was 3.21 × 10⁻⁶.-8 mm 3 / (N·m).

[0031] Comparative Example 1

[0032] This comparative example is identical to Example 1 except that the dispersant SDBS was not added. The Ni-Co-Al2O3 composite coating was prepared using the above method. Testing showed that the average grain size of this coating was 232 nm, which is 137 nm coarser than that of Example 1. Figure 2 The TEM image of this comparative example shows obvious nano-Al₂O₃ agglomerates with a size of 513 nm; compared to Example 1, the agglomerate size increased by 421 nm. Numerous micropores appear within the coating; simultaneously, its hardness is significantly reduced to 315 HV. 0.1 Compared to Example 1, the wear resistance was reduced by 30%. The coating's abrasion resistance deteriorated, with an average coefficient of friction of 0.69 and a wear rate of 1.27 × 10⁻⁶. -7 mm 3 / (N·m), which is 295% higher than that of Example 1.

[0033] Example 2

[0034] 1. Substrate pretreatment: The Cu alloy substrate was polished with 400#, 800#, and 1200# sandpaper; electropolishing was performed for 8 seconds using a 5 V voltage and a perchloric acid-methanol solution with a volume ratio of HClO4:CH3OH=4:1; the substrate was immersed in a 14.5 vol% HCl solution for 24 min to remove the surface oxide film; the substrate was then immersed in a 4.5 vol% H2SO4 solution for 20 s to activate it; the substrate was rinsed with deionized water for 10 min to remove residual acid; and finally dried with an air gun.

[0035] 2. Electrolyte preparation: Weigh out 350 g of Ni(NH2SO3)2·4H2O, 50 g of Co(NH2SO3)2·4H2O, 31.5 g of NiCl2·6H2O, 20 g of C7H5O3NS, 5 g of nano-Al2O3, and 4 g of SDBS. Pour the weighed materials into the electrolytic cell. Add deionized water to the electrolytic cell to a volume of 5 L.

[0036] 3. Electrolyte ultrasonic dispersion treatment: The electrolytic cell was heated to 49 ºC; H3BO3 was added to adjust the pH of the solution to 4.9; the ultrasonic power was adjusted to 350 W, and ultrasonic dispersion was carried out for 2.5 h to obtain an electrolyte in which nano-Al2O3 was uniformly dispersed.

[0037] 4. Electroplating Coating Preparation: Connect the substrate alloy to the cathode of the DC power supply; connect the Ni plate to the anode; turn on the power to start electroplating, and adjust the DC power supply current to 3.5 A / dm. 2 Maintain the electrolyte temperature at 49 ºC and the pH value at 4.9; after electroplating for 2 hours, turn off the power, remove the Cu alloy plate with the Ni-Co-Al2O3 coating, rinse with deionized water, and blow dry with an air gun to obtain the electroplated coating.

[0038] The Ni-Co-Al2O3 composite coating was prepared using the above method. The prepared coating has uniform grain size and no coarse grains are generated. According to software statistics, the average grain size of the coating is 172 nm. The nano-Al2O3 inside the coating is uniformly dispersed without obvious agglomeration, and the agglomeration size is no larger than 132 nm. Figure 3 The image shown is a SEM image of the coating after polishing in Example 2. The coating is uniform and dense, with no observed pores. The hardness of this coating is 353 HV. 0.1 After being rubbed by GCr15 steel balls, the average coefficient of friction of the coating was 0.60, and the wear rate calculated by volumetric wear rate was 4.34 × 10⁻⁶. -8 mm 3 / (N·m).

[0039] Comparative Example 2

[0040] Compared to Example 2, Comparative Example 2 only omitted the ultrasonic dispersion treatment of the electrolyte; all other parameters and processes were identical to Example 2. The Ni-Co-Al2O3 composite coating prepared using Comparative Example 2 exhibited uniform grain size. According to software statistics, the average grain size of this coating was 211 nm, an increase of 39 nm compared to Example 2. Furthermore, the coating of Comparative Example 2 showed large nano-Al2O3 agglomerates with a size of approximately 325 nm, an increase of 193 nm compared to Example 2. The hardness of the coating in Comparative Example 2 decreased by 37 HV compared to Example 2. 0.1 316 HV 0.1 Its wear resistance decreased, with an average friction coefficient of 0.66 and a wear rate of 9.32 × 10⁻⁶. -8 mm 3 / (N·m), which is 115% higher than that of Example 2.

[0041] Example 3

[0042] 1. Substrate pretreatment: The Cu alloy substrate was polished with 400#, 800#, and 1200# sandpaper; electropolishing was performed for 10 s using a 5.5 V voltage and a perchloric acid-methanol solution (volume ratio of HClO4:CH3OH=4:1); the substrate was immersed in a 15.2 vol% HCl solution for 20 min to remove the surface oxide film; the substrate was then immersed in a 5.6 vol% H2SO4 solution for 30 s to activate it; the substrate was rinsed with deionized water for 5 min to remove residual acid; and finally dried with an air gun.

[0043] 2. Electrolyte preparation: Weigh out 420 g of Ni(NH2SO3)2·4H2O; 40 g of Co(NH2SO3)2·4H2O; 35.5 g of NiCl2·6H2O; 18 g of C7H5O3NS; 15 g of nano-Al2O3; and 6 g of SDBS. Pour the weighed materials into the electrolytic cell. Add deionized water to the electrolytic cell to a volume of 5 L.

[0044] 3. Electrolyte ultrasonic dispersion treatment: Heat the electrolyte to 50 ºC; add H3BO3 to adjust the pH of the solution to 5.0; adjust the ultrasonic power to 390 W and ultrasonically disperse for 2 h to obtain an electrolyte with uniformly dispersed nano-Al2O3.

[0045] 4. Electroplating Coating Preparation: Connect the substrate alloy to the cathode of the DC power supply; connect the Ni plate to the anode; turn on the power to start electroplating, and adjust the DC power supply current to 3.0 A / dm. 2 Maintain the electrolyte temperature at 50 ºC and the pH value at 5.0; after electroplating for 2 hours, turn off the power, remove the Cu alloy plate with Ni-Co-Al2O3 coating, rinse with deionized water, and blow dry with an air gun to obtain the electroplated coating.

[0046] The Ni-Co-Al2O3 composite coating prepared by the above method has uniform grain size and no coarse grains. According to software statistics, the average grain size of this coating is 166 nm. Figure 4 This is a TEM image of the nano-Al2O3 in the coating of Example 3. It shows that the nano-Al2O3 is well dispersed with no obvious agglomeration; the agglomeration size is no larger than 100 nm. The coating is uniform and dense, with a hardness of 366 HV. 0.1 After friction testing with GCr15 steel balls, the average coefficient of friction was 0.56. The calculated wear rate was 3.53 × 10⁻⁶. -8 mm 3 / (N·m).

[0047] Comparative Example 3

[0048] Compared to Example 3, Comparative Example 3 only lacked the addition of nano-Al2O3; all other parameters and processes were identical to Example 3. The Ni-Co coating prepared using Comparative Example 3 exhibited uniform grain size, with an average grain size of approximately 423 nm, representing a grain coarsening of 257 nm compared to Example 3. The hardness of this coating decreased by 46 HV compared to Example 3. 0.1 320 HV 0.1 The coating exhibits significantly reduced wear resistance, with an average coefficient of friction of 0.72 and a wear rate of 1.68 × 10⁻⁶. -9 mm 3 / (N·m), which is 377% higher than that of Example 3.

[0049] Example 4

[0050] 1. Substrate pretreatment: The substrate alloy was polished with 400#, 800#, and 1200# sandpaper; electropolishing was performed for 10 s using a 5.5 V voltage and a perchloric acid-methanol solution with a volume ratio of HClO4:CH3OH=4:1; the substrate was immersed in a 15.2 vol% HCl solution for 20 min to remove the surface oxide film; the substrate was then immersed in a 5.6 vol% H2SO4 solution for 30 s to activate it; the substrate was rinsed with deionized water for 5 min to remove residual acid; and finally dried with an air gun.

[0051] 2. Electrolyte preparation: Weigh out 450 g of Ni(NH2SO3)2·4H2O, 30 g of Co(NH2SO3)2·4H2O, 37.5 g of nickel chloride NiCl2·6H2O, 25 g of saccharin C7H5O3NS, 12.5 g of nano-Al2O3, and 5 g of sodium dodecylbenzenesulfonate SDBS. Pour the weighed materials into the electrolytic cell. Add deionized water to the electrolytic cell to a volume of 5 L.

[0052] 3. Electrolyte ultrasonic dispersion treatment: The electrolyte was heated to 51 ºC; H3BO3 was added to adjust the pH of the solution to 4.5; the ultrasonic power was adjusted to 385 W, and ultrasonic dispersion was carried out for 3 h to obtain an electrolyte in which nano-Al2O3 was uniformly dispersed.

[0053] 4. Electroplating Coating Preparation: Connect the substrate alloy to the cathode of the DC power supply; connect the Ni plate to the anode; turn on the power to start electroplating, and adjust the DC power supply current to 2.5 A / dm. 2 Maintain the electrolyte temperature at 51 ºC and the pH value at 4.5; after electroplating for 2 hours, turn off the power, remove the Cu alloy plate with Ni-Co-Al2O3 coating, rinse with deionized water, and blow dry with an air gun to obtain the electroplated coating.

[0054] A Ni-Co-Al2O3 composite coating was prepared using the above method. The prepared coating exhibits uniform grain size with no coarse grains. According to software statistics, the average grain size of the coating is 151 nm. Furthermore, the nano-Al2O3 within the coating is uniformly dispersed with no obvious agglomeration; the agglomerate size is no larger than 95 nm. The coating is uniform and dense, with a hardness of 373 HV. 0.1 . Figure 5 The friction curve for Example 4 shows that the average coefficient of friction of the coating is 0.59; the calculated wear rate is 3.92 × 10⁻⁶. -8 mm 3 / (N·m).

[0055] Example 5

[0056] 1. Substrate pretreatment: The substrate alloy was polished with 400#, 800#, and 1200# sandpaper; electropolishing was performed for 9 s using a 5.1 V voltage and a perchloric acid-methanol solution with a volume ratio of HClO4:CH3OH=4:1; the substrate was immersed in a 14.9 vol% HCl solution for 30 min to remove the surface oxide film; the substrate was then immersed in a 5.8 vol% H2SO4 solution for 40 s to activate it; the substrate was rinsed with deionized water for 5 min to remove residual acid; and finally dried with an air gun.

[0057] 2. Electrolyte preparation: Weigh out 370 g of Ni(NH2SO3)2·4H2O, 20 g of Co(NH2SO3)2·4H2O, 32.5 g of NiCl2·6H2O, 15 g of C7H5O3NS, 12 g of nano-Al2O3, and 5 g of SDBS. Pour the weighed materials into the electrolytic cell. Add deionized water to the electrolytic cell to a volume of 5 L.

[0058] 3. Electrolyte ultrasonic dispersion treatment: Heat the electrolyte to 52 ºC; add H3BO3 to adjust the pH of the solution to 4.6; adjust the ultrasonic power to 400 W and ultrasonically disperse for 3 h to obtain an electrolyte with uniformly dispersed nano-Al2O3.

[0059] 4. Electroplating Coating Preparation: Connect the substrate alloy to the cathode of the DC power supply; connect the Ni plate to the anode; turn on the power to start electroplating, and adjust the DC power supply current to 2.6 A / dm. 2 Maintain the electrolyte temperature at 52 ºC and the pH value at 4.6; after electroplating for 2 hours, turn off the power, remove the Cu alloy plate with Ni-Co-Al2O3 coating, rinse with deionized water, and blow dry with an air gun to obtain the electroplated coating.

[0060] A Ni-Co-Al2O3 composite coating was prepared using the above method. The prepared coating exhibits uniform grain size with no coarse grains. According to software statistics, the average grain size of the coating is 145 nm. Furthermore, the nano-Al2O3 within the coating is uniformly dispersed without significant agglomeration, and its size is no greater than 98 nm. The coating is uniform and dense, with a hardness of 421 HV. 0.1 After friction testing with GCr15 steel balls, the average coefficient of friction of the coating was 0.59. The calculated wear rate was 4.13 × 10⁻⁶. -8 mm 3 / (N·m).

[0061] Friction testing was conducted using a ball-and-disc friction method. The grinding balls were 6 mm diameter GCr15 steel balls with a grinding radius of 3 mm. The applied load was 5 N, the rotational speed was 200 r / min, and the test time was 30 min. The wear rate was calculated using the Archard model, with the following formula: W V =V / S=V / (F N ×S), where W V Wear volume (mm) 3 / (N·m), V is the wear volume (mm²) 3 ), F N Let s be the applied normal load (N) and s be the sliding distance (m).

Claims

1. A high wear-resistant electroplated Ni-Co-Al2O3 coating, characterized in that: The electrolyte composition and dosage are as follows: Ni(NH2SO3)2·4H2O 70~90 g / L; Co(NH2SO3)2·4H2O 4~10 g / L; H3BO3 35~50 g / L; NiCl2·6H2O 6.0~7.5 g / L; C7H5O3NS 3~5 g / L; nano-α-Al2O3 2~3 g / L with a particle size of 30~50 nm; sodium dodecylbenzenesulfonate 0.8~1.2 g / L. The coating is prepared by ultrasonic-assisted DC electroplating. The average grain size of the Ni-Co matrix metal in the coating is 95~172 nm; the agglomerate size of the nano-Al2O3 is no greater than 132 nm; and the hardness is 353~452 HV. 0.1 The wear rate was 3.21 × 10⁻⁶. -8 ~4.34×10 -8 mm 3 / (N·m); It has the characteristics of high Al2O3 dispersibility, high density and high wear resistance.

2. The method for preparing a high wear-resistant electroplated Ni-Co-Al2O3 coating as described in claim 1, characterized in that, Includes the following steps: (1) Substrate pretreatment: The specific pretreatment depends on the type of substrate; (2) Electrolyte preparation: Prepare Ni(NH2SO3)2·4H2O, Co(NH2SO3)2·4H2O, NiCl2·6H2O, C7H5O3NS, nano Al2O3 and sodium dodecylbenzenesulfonate according to the required ratio; weigh them and pour them into the electrolytic cell; add the corresponding volume of deionized water; (3) Electrolyte ultrasonic dispersion treatment: Heat the prepared electrolyte to 48~52 ºC; add H3BO3 to adjust the pH of the solution to 4.5~5.0; ultrasonically disperse the electrolyte to make the nano Al2O3 uniformly dispersed. (4) Electroplating coating preparation: Connect the substrate alloy to the cathode of the DC power supply; connect the Ni plate to the anode to replenish Ni ions during electroplating; turn on the power supply to start electroplating, and adjust the DC power supply current to 2.5~3.5 A / dm. 2 The electroplating process involves adding Co(NH2SO3)2·4H2O solution to replenish Co ions and maintaining the electrolyte temperature and pH value stable. After obtaining a coating of a certain thickness through electroplating, the power is turned off, the substrate alloy is removed, rinsed with deionized water, and dried with an air gun to obtain the electroplated coating.

3. The method for preparing a high wear-resistant electroplated Ni-Co-Al2O3 coating as described in claim 2, characterized in that: The following steps, when using a Cu alloy as the substrate alloy and a 5 L electrolyte, are as follows: (1) Substrate pretreatment: The Cu alloy substrate was polished with 400#, 800#, and 1200# sandpaper; the voltage was 4.5~5.5 V, the electrolyte was perchloric acid methanol solution with a volume ratio of HClO4:CH3OH=4:1, and the electropolishing was performed for 8~10 s; the substrate was immersed in 14.5~15.5 vol% HCl solution for 20~30 min to remove the surface oxide film; the substrate was immersed in 4.5~6.0 vol% H2SO4 solution for 20~40 s to activate the substrate; the substrate was rinsed with deionized water for 5~10 min to remove residual acid; and the substrate was dried with an air gun. (2) Electrolyte preparation: Weigh 350-450 g of nickel sulfamate Ni(NH2SO3)2·4H2O, 20-50 g of cobalt sulfamate Co(NH2SO3)2·4H2O, 30-37.5 g of nickel chloride NiCl2·6H2O, 15-25 g of saccharin C7H5O3NS, 10-15 g of nano Al2O3, and 4-6 g of sodium dodecylbenzenesulfonate SDBS using an electronic balance; pour the weighed materials into the electrolytic cell; add deionized water to the electrolytic cell to a total volume of 5 L; (3) Electrolyte ultrasonic dispersion treatment: The electrolytic cell is heated to 48~52 ºC; H3BO3 is added to adjust the pH of the solution to 4.5~5.0; the ultrasonic power is adjusted to 350~400 W, and the electrolyte is ultrasonically dispersed for 2~3 h to obtain a uniformly dispersed electrolyte of nano Al2O3. (4) Electroplating coating preparation: Connect the substrate alloy to the cathode of the DC power supply; connect the Ni plate to the anode; turn on the power supply to start electroplating, and adjust the DC power supply current to 2.5~3.5 A / dm. 2 The electroplating process involves adding Co(NH2SO3)2·4H2O solution to replenish Co ions, maintaining the electrolyte temperature at 48~52 ºC and the pH value at 4.5~5.

0. After obtaining a coating of a certain thickness through electroplating, the power is turned off, the substrate alloy is removed, rinsed with deionized water, and dried with an air gun to obtain the electroplated coating.

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