A preparation method of gradient structure nickel-copper-phosphorus alloy and its product

Abstract

The present invention discloses a gradient structure nickel-copper-phosphorus alloy and a preparation method thereof, and relates to the technical field of metal materials. The preparation method provided by the present invention utilizes an electrochemical deposition process, and by computer-controlled electroplating parameters, a dual gradient structure with different distribution forms can be prepared in the nickel-copper-phosphorus ternary alloy, including a grain size gradient of micron-scale coarse crystals-ultrafine crystals-nanocrystalline crystals, and also includes a composition gradient with gradually changing copper and phosphorus content. Constructing a gradient structure in the nickel-copper-phosphorus ternary alloy system can eliminate the sudden changes in various properties caused by changes in component composition, and achieve excellent mechanical properties. At the same time, the addition of copper elements can further enhance the corrosion resistance, anti-protein adhesion and anti-algae adhesion of the alloy. The gradient structure nickel-copper-phosphorus alloy prepared by the above method has excellent mechanical properties and the multifunctionality of integrated anti-corrosion and anti-fouling, which can further broaden the application scope of nickel-based alloys and provide technical reserves for future engineering applications.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal materials, and more specifically, relates to a preparation method of a gradient structure nickel-copper-phosphorus alloy and a product thereof. Background Art

[0002] The spatial gradient distribution of microstructure, composition or atomic structure is a significant feature of gradient materials that are commonly found in nature. The introduction of the gradient concept has made researchers realize that the structure of metal materials can be constructed into a gradient structure at the microscale, thereby improving the overall performance of the metal material and realizing the multifunctionality of the overall material. Because the sample size is almost unrestricted and the controllability is good, the electrodeposition method has shown unique advantages in the current common preparation technology of gradient structured metal materials. Patent applications with publication numbers CN104862748A and CN111411377A respectively announced "A grain-scale gradient metal nickel and a controllable preparation method thereof" and "A new gradient structured nickel-phosphorus alloy and a preparation method thereof". However, the above methods have not yet involved the preparation and control of gradient structured ternary alloys.

[0003] Adding copper to nickel or nickel-phosphorus alloys can improve the overall material's thermal stability, corrosion resistance, and protein adhesion resistance. However, the standard electrode potentials of nickel and copper differ significantly, making co-deposition of nickel and copper possible only with the use of appropriate complexing agents. Based on existing electrodeposition processes, it is not yet possible to directly create gradient structures in nickel-copper-phosphorus ternary alloys.

[0004] In view of this, it is necessary to develop a gradient structure nickel-copper-phosphorus alloy and a preparation method thereof. Summary of the Invention

[0005] In response to the defects of the prior art, the purpose of the present invention is to provide a method for preparing a gradient structure nickel-copper-phosphorus alloy and its product. Through composition design and process design, combined with precise control and adjustment of process parameters, a ternary alloy with a gradient change in composition and grain size is prepared, aiming to solve the technical problem that the prior art cannot directly prepare a gradient nickel-copper-phosphorus ternary alloy.

[0006] To achieve the above objectives, the present invention provides a method for preparing a gradient structure nickel-copper-phosphorus alloy. The method adopts an electrochemical deposition method, uses nickel as a consumable anode, and controls the current density and the concentration of additives in the electroplating solution. Under the action of direct current, a gradient structure nickel-copper-phosphorus ternary alloy with both a chemical composition gradient change and a grain size gradient change is deposited and prepared. The additives in the electroplating solution are selected from copper salts, citrates, hypophosphites, sodium saccharin, phosphorous acid and / or citric acid. The current density is 20 to 200 mA / cm 2 range, or from 20 to 40 mA / cm 2Gradually changes to 80~120mA / cm 2 within the range.

[0007] Furthermore, the copper salt is copper sulfate, and the concentration of copper sulfate is controlled as follows: starting from the start of electrochemical deposition, the copper sulfate concentration is maintained at 0 until the 5th to 5.5th hour, and then the copper sulfate concentration is gradually increased until the copper sulfate concentration reaches 3 to 5 g / L within the 8th to 8.5th hour, and then the copper sulfate concentration is further gradually increased until the copper sulfate concentration reaches 7 to 12.5 g / L within the 12th to 12.5th hour, and the copper sulfate concentration is still further gradually increased until the copper sulfate concentration reaches 10 to 25 g / L within the 16th to 16.5th hour, and the electrochemical deposition is continued by maintaining this concentration, and the electrochemical deposition is completed in half an hour to one hour.

[0008] Furthermore, the hypophosphite is sodium hypophosphite, and the concentration of sodium hypophosphite is controlled as follows: starting from the start of electrochemical deposition, until the 5th to 5.5 hours, the concentration of sodium hypophosphite is maintained at 0, and then the concentration of sodium hypophosphite is gradually increased until the concentration of sodium hypophosphite reaches 0.05 to 0.15 g / L within the 8th to 8.5 hours, and then the concentration of sodium hypophosphite is further gradually increased until the concentration of sodium hypophosphite reaches 0.2 to 0.4 g / L within the 12th to 12.5 hours, and the concentration of sodium hypophosphite is still further gradually increased until the concentration of sodium hypophosphite reaches 0.5 to 5 g / L within the 16th to 16.5 hours, and the electrochemical deposition is continued at this concentration, and it takes half an hour to one hour to complete the electrochemical deposition.

[0009] Furthermore, the citrate is sodium citrate dihydrate or sodium citrate pentahydrate, and the concentration of sodium citrate dihydrate is controlled as follows: from the start of electrochemical deposition, until the 5th to 5.5th hour, the concentration of sodium citrate dihydrate is maintained at 0, and then the concentration of sodium citrate dihydrate is gradually increased until the concentration of sodium citrate dihydrate reaches 20 to 70 g / L within the 8th to 8.5th hour, and then the concentration of sodium citrate dihydrate is further gradually increased until the concentration of sodium citrate dihydrate reaches 50 to 110 g / L within the 12th to 12.5th hour, and the concentration of sodium citrate dihydrate is still further gradually increased until the concentration of sodium citrate dihydrate reaches 90 to 150 g / L within the 16th to 16.5th hour, and the electrochemical deposition is continued by maintaining this concentration, and the electrochemical deposition takes half an hour to one hour to complete.

[0010] Furthermore, the concentration of saccharin sodium is controlled as follows: from the start of electrochemical deposition, the concentration of saccharin sodium is maintained at 0.5 g / L until the 5th to 5.5 hours, and then the concentration of saccharin sodium is gradually increased until the concentration of saccharin sodium reaches 2 to 5 g / L within the 8th to 8.5 hours, and then the concentration of saccharin sodium is further gradually increased until the concentration of saccharin sodium reaches 4 to 10 g / L within the 12th to 12.5 hours, and the concentration of saccharin sodium is still further gradually increased until the concentration of saccharin sodium reaches 5 to 15 g / L within the 16th to 16.5 hours, and the electrochemical deposition is continued while maintaining this concentration. It takes half an hour to one hour to complete the electrochemical deposition.

[0011] Furthermore, the components contained in the electrochemical deposition plating solution and the content of each component are as follows: nickel sulfate hexahydrate or nickel aminosulfonate tetrahydrate with a concentration of 0.2-0.5 mol / L, nickel chloride hexahydrate with a concentration of 10-20 g / L, boric acid with a concentration of 10-40 g / L, sodium tetraborate decahydrate with a concentration of 0-40 g / L, potassium sodium tartrate with a concentration of 0-10 g / L, sodium dodecylbenzenesulfonate with a concentration of 0.3-0.6 g / L, the plating solution pH is 5.0±0.2, the plating solution temperature is 40-80°C, preferably 70-75°C, and the temperature of the plating solution is controlled as follows: first stage: the temperature of the plating solution is controlled to 75±1°C within 5-5.5 hours after the start of electrochemical deposition, and second stage: after the end of the first stage, the temperature of the plating solution is adjusted to 70±1°C and maintained until the end of deposition.

[0012] Furthermore, the substrate is pretreated before plating, and the pretreatment includes mechanical polishing and surface degreasing of the substrate. Mechanical polishing is to polish the surface of the substrate with 200#, 400# and 800# sandpaper in sequence, and surface degreasing is to clean the surface of the substrate with an organic solvent, and the organic solvent is acetone and / or ethanol.

[0013] According to a second aspect of the present invention, a gradient structure nickel-copper-phosphorus alloy prepared by a method for preparing the gradient structure nickel-copper-phosphorus alloy as described above is provided.

[0014] Furthermore, the grain size of the gradient structure nickel-copper-phosphorus alloy is gradually refined from 10 to 20 μm to 10 to 30 nm, and the closer to the surface of the electroplating layer, the finer the grains.

[0015] Furthermore, the atomic percentages of copper and phosphorus in the gradient structure nickel-copper-phosphorus alloy are 5-40% and 1-15% respectively.

[0016] In general, the above technical solutions conceived by the present invention have the following beneficial effects compared with the prior art:

[0017] The present invention provides a gradient structure nickel-copper-phosphorus alloy and a preparation method thereof. By utilizing electrochemical deposition and finely controlling the electroplating parameters, a nickel-copper-phosphorus ternary alloy with a precisely controllable gradient distribution and a gradient change in grain size with a micron-scale coarse-grained-ultrafine-grained-nanocrystalline transition can be prepared. The copper content and phosphorus content of the copper-phosphorus ternary alloy simultaneously change in a gradient. In the present invention, the multi-level construction of the gradient structure can avoid the sudden change in the metal properties of each component, thereby regulating the microstructure of the overall material within a larger composition and scale space. The gradient structure nickel-copper-phosphorus alloy prepared by the above method can give full play to the unique performance advantages corresponding to each component element and provide a technical reserve for future engineering applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The cross-sectional microstructure of the first sample of the typical electrochemically deposited gradient nickel-copper-phosphorus alloy in an embodiment of the present invention;

[0019] Figure 2 yes Figure 1 Element distribution diagram of the cross section of the first sample;

[0020] Figure 3 yes Figure 1 The cross-sectional hardness distribution of the first specimen;

[0021] Figure 4 The cross-sectional microstructure of the second sample of the typical electrochemically deposited gradient nickel-copper-phosphorus alloy according to the embodiment of the present invention;

[0022] Figure 5 In the embodiment of the present invention Figure 4 Element distribution diagram of the cross section of the second sample;

[0023] Figure 6 In the embodiment of the present invention Figure 4 The cross-sectional hardness distribution of the second specimen;

[0024] Figure 7 The cross-sectional microstructure of the third sample of the electrochemically deposited typical gradient structure nickel-copper-phosphorus alloy in the embodiment of the present invention;

[0025] Figure 8 In the embodiment of the present invention Figure 7 Cross-sectional element distribution diagram of the third specimen;

[0026] Figure 9 In the embodiment of the present invention Figure 7 The cross-sectional hardness distribution of the third specimen;

[0027] Figure 10 This is a comparison chart of the anti-protein adhesion rates of the first sample, the second sample, the third sample and No. 45 steel in the embodiment of the present invention;

[0028] Figure 11 This is a comparison chart of the weight loss rates of the first sample, the second sample, the third sample and No. 45 steel after 48 hours of seawater scouring in an embodiment of the present invention. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0030] The preparation method provided herein utilizes electrochemical deposition technology. Computer-controlled deposition parameters enable the production of gradient-structured nickel-copper-phosphorus alloys with varying distribution patterns, ranging from micron-sized coarse grains to nanocrystalline grains, and gradient changes in copper and phosphorus content. Specifically, a gradient-structured nickel-copper-phosphorus alloy and its preparation method utilize electrochemical deposition technology with nickel as a consumable anode. Computer-controlled current density and the concentration of various additives in the plating solution vary over time. Under the action of a direct current, a gradient-structured nickel-copper-phosphorus alloy with both chemical composition gradients and grain size gradients is deposited. The additives include copper salt, hypophosphite or phosphorous acid, citric acid or citrate, and sodium saccharin. The copper salt provides the copper element in the nickel-copper-phosphorus alloy coating, the hypophosphite or phosphorous acid provides the phosphorus element, the citric acid or citrate complexes the copper and nickel ions, and the sodium saccharin refines the grains and optimizes the internal stress of the coating. The anode is a 99% pure nickel plate, and the cathode is selected from steel, titanium, copper, a copper alloy, or nickel.

[0031] Among them, the change of current density over time is mainly: with the increase of deposition time, the current density is maintained at 20-100mA / cm 2 A specific value within the range, or from 20-40mA / cm 2 Gradually change to 80-120mA / cm 2 .

[0032] In a preferred embodiment of the present invention, the copper salt is copper sulfate, the hypophosphite is sodium hypophosphite, and the citrate is sodium citrate dihydrate or sodium citrate pentahydrate. In an optional embodiment, the additives include copper sulfate, sodium hypophosphite, sodium citrate dihydrate, and sodium saccharin.

[0033] The changes in the concentration of additives over time are mainly as follows: with the increase of sedimentation time, the concentrations of copper sulfate and sodium hypophosphite increase from 0 g / L to 10-25 g / L and 0.5-5 g / L, respectively; the concentration of sodium citrate dihydrate increases from 0 g / L to 90-150 g / L; and the concentration of saccharin sodium increases from 0-5 g / L to 10-15 g / L.

[0034] In an optional embodiment, starting from the electrochemical deposition, as the deposition time increases, the concentration of copper sulfate is constant at 0 g / L within 5-5.5 hours of the start of electrochemical deposition, then the concentration of the copper sulfate is controlled to reach 3-5 g / L within the 8th-8.5th hour, and then the concentration of the copper sulfate is reached to 7-12.5 g / L within the subsequent 12th-12.5th hour, and then the concentration of the copper sulfate is reached to 10-25 g / L within the 16th-16.5th hour, and finally, this concentration is maintained for half an hour to one hour, and deposition is completed. Within each concentration adjustment period, as the deposition time increases, the adjustment of the copper sulfate concentration is uniform. In addition, in other embodiments, copper sulfate can also be added to the plating solution at the beginning of electrochemical deposition.

[0035] In an optional embodiment, starting from the start of electrochemical deposition, as the deposition time increases, the concentration of sodium hypophosphite is constant at 0 g / L within the 5th to 5.5th hour from the start of electrochemical deposition, and then the concentration of sodium hypophosphite is controlled to gradually reach 0.05-0.15 g / L within the 8th to 8.5th hour, and then the concentration of the sodium hypophosphite is gradually increased to 0.2-0.4 g / L within the subsequent 12th to 12.5th hour, and then the concentration of the sodium hypophosphite is increased to 0.5-5 g / L within the 16th to 16.5th hour, and finally maintained at this concentration for half an hour to one hour thereafter to complete the electrochemical deposition. In a preferred embodiment, as the deposition time increases, the concentration of sodium hypophosphite is adjusted at a uniform rate. In addition, in other embodiments, sodium hypophosphite can also be added to the plating solution at the start of electrochemical deposition.

[0036] In an optional embodiment, starting from the start of electrochemical deposition, as the deposition time increases, the concentration of sodium citrate dihydrate is constant at 0 g / L within the 5th to 5.5th hour of the start of electrochemical deposition, and then the concentration of the sodium citrate dihydrate is controlled to reach 20-70 g / L within the 8th to 8.5th hour, and then the concentration of the sodium citrate dihydrate is reached to 50-110 g / L within the subsequent 12th to 12.5th hour, and then the concentration of the sodium citrate dihydrate is gradually increased to 90-150 g / L within the subsequent 16th to 16.5th hour, and finally maintained at this concentration within the subsequent 0.5-1 hour until the end of deposition. In a preferred embodiment, as the deposition time increases, the concentration of sodium citrate dihydrate is adjusted at a uniform rate.

[0037] In an alternative embodiment, starting from the start of electrochemical deposition, as deposition time increases, the concentration of saccharin sodium is kept constant at 0.5 g / L within the 5th to 5.5th hour after the start of electrochemical deposition, then the concentration of saccharin sodium is controlled to reach 2-5 g / L within the 8th to 8.5th hour, then the concentration of saccharin sodium is increased to 4-10 g / L within the 12th to 12.5th hour, then the concentration of saccharin sodium is increased to 5-15 g / L within the 16th to 16.5th hour, and finally this concentration is maintained for the next half hour to one hour until the end of deposition. In a preferred embodiment, as deposition time increases, the concentration of saccharin sodium is adjusted at a uniform rate.

[0038] In other embodiments, the electrochemical deposition parameters can be adaptively controlled according to the gradient structure nickel-copper-phosphorus alloy material prepared as needed.

[0039] In a preferred embodiment of the present invention, the above-mentioned process further includes preparing a plating solution before electrochemical deposition, so that the plating solution contains the following components: nickel sulfate hexahydrate or nickel sulfamate tetrahydrate at a concentration of 0.2-0.5 mol / L, nickel chloride hexahydrate at a concentration of 10-20 g / L, boric acid at a concentration of 10-40 g / L, sodium tetraborate decahydrate at a concentration of 0-40 g / L, potassium sodium tartrate at a concentration of 0-10 g / L, and sodium dodecylbenzenesulfonate at a concentration of 0.3-0.6 g / L. The pH of the plating solution is adjusted to 5.0±0.2. The temperature of the plating solution is 40-80°C, preferably 70-75°C. Preferably, during the electrochemical deposition process, the temperature of the plating solution is constant within the range of 69-71°C. More preferably, during the electrochemical deposition process, the temperature of the plating solution is controlled as follows:

[0040] Stage a: controlling the temperature of the plating solution to 75° C. within 5-5.5 hours after the start of electrochemical deposition;

[0041] Stage b: After stage a, the temperature of the plating solution is adjusted to 70° C. and maintained until the deposition is completed.

[0042] Under the above-mentioned conditions of plating solution composition, pH and temperature, efficient co-deposition of metallic nickel, metallic copper and phosphorus can be achieved on the cathode.

[0043] In an embodiment in which the present invention is preferably applied, the preparation method further comprises pre-treating the substrate before plating. In other embodiments, the pre-treatment comprises mechanically grinding and polishing the substrate and degreasing the surface. Mechanical grinding and polishing are used to eliminate fine unevenness, oxide scale and various macro defects on the substrate surface, thereby improving the flatness of the substrate surface. In other embodiments, mechanical grinding and polishing is to polish the surface of the substrate using 200#, 400# and 800# sandpaper in sequence. In other embodiments, surface degreasing is to clean the substrate surface with an organic solvent, and the organic solvent is preferably acetone or ethanol. Surface degreasing is used to facilitate the implementation of electroplating, and the oil stains on the substrate surface can be removed by utilizing the principle of similar compatibility of organic solvents.

[0044] In the gradient structure nickel-copper-phosphorus ternary alloy prepared by the above preparation method, the grain size of the gradient structure nickel-copper-phosphorus alloy is gradually refined from 10-20 μm to 10-30 nm, and the closer to the surface, the smaller the grain size.

[0045] The preparation method provided by the present invention achieves controllable preparation of a gradient nickel-copper-phosphorus alloy by computer-controlled changes in additive concentration. The resulting gradient nickel-copper-phosphorus alloy exhibits high quality and controllable microstructure and mechanical properties. In a preferred embodiment of the present invention, the atomic percentages of copper and phosphorus in the gradient nickel-copper-phosphorus alloy range from 5 to 40% and 1 to 15% respectively.

[0046] The characteristics and properties of the gradient structure ternary alloy of the present invention are further described in detail below with reference to the examples.

[0047] Example 1

[0048] This embodiment provides a method for preparing a gradient structure nickel-copper-phosphorus alloy, which includes the following steps:

[0049] (1) In this embodiment, a metal nickel plate with a purity of 99.6% is used as a consumable anode and a metal nickel plate is used as a cathode.

[0050] Prepare 1000ml of plating solution. The base plating solution contains the following chemical reagents at the following concentrations: 0.5mol / L NiSO4·6H2O, 20g / L NiCl2·6H2O, 30g / L H3BO3, and 0.5g / L CHNaOS. Weigh these chemicals using a scale and dissolve them in ultrapure water in a 1000ml beaker. Stir the solution with a magnetic stirrer until it becomes clear. Adjust the pH to 5.0±0.2 with dilute sulfuric acid or sodium hydroxide solution. Use a heater to maintain the initial bath temperature at 75±1°C.

[0051] (2) Use computer to control current density and additive concentration:

[0052] Current density: During the entire electrochemical deposition process, the current density remains constant at 20 mA / cm 2 .

[0053] At the same time, the concentration of the additive saccharin sodium was regulated: the concentration of saccharin sodium was kept constant at 0.5 g / L from the start of electrochemical deposition until the 5th hour, then the concentration of saccharin sodium increased from 0.5 g / L to 2 g / L within the 8th hour, then the concentration of saccharin sodium increased from 2 g / L to 4 g / L within the 12th hour, then the concentration of saccharin sodium increased from 4 g / L to 5 g / L within the 16th hour, and finally the concentration of saccharin sodium was maintained at 5 g / L within one hour.

[0054] At the same time, the concentration of the additive sodium hypophosphite was regulated: starting from the start of electrochemical deposition, the concentration of sodium hypophosphite was kept constant at 0 g / L within the 5th hour from the start of electrochemical deposition, and then the concentration of sodium hypophosphite increased from 0 g / L to 0.05 g / L within the 8th hour, and then the concentration of sodium hypophosphite increased from 0.05 g / L to 0.2 g / L within the 12th hour, and then the concentration of sodium hypophosphite increased from 0.2 g / L to 0.5 g / L within the 16th hour thereafter. Finally, the concentration of sodium hypophosphite was maintained at 0.5 g / L within one hour.

[0055] At the same time, the concentration of the additive copper sulfate was regulated: starting from the start of electrochemical deposition, the concentration of copper sulfate was kept constant at 0 g / L within the first 5 hours after the start of electrochemical deposition, and the concentration of copper sulfate gradually increased from 0 g / L to 3 g / L within the next 8 hours, and then gradually increased from 3 g / L to 7 g / L within the next 12 hours, and then gradually increased from 7 g / L to 10 g / L within the next 4 hours, and finally the concentration of copper sulfate was maintained at 10 g / L within 1 hour.

[0056] At the same time, the concentration of the additive sodium citrate dihydrate was regulated: starting from the start of electrochemical deposition, the concentration of sodium citrate dihydrate was kept constant at 0 g / L from the start of electrochemical deposition to the 5th hour, and then the concentration of sodium citrate dihydrate increased from 0 g / L to 20 g / L within the 8th hour, and then increased from 20 g / L to 50 g / L within the 12th hour, and then increased from 50 g / L to 90 g / L within the 16th hour. Finally, the electrochemical deposition took one hour, and the concentration of sodium citrate dihydrate was maintained at 90 g / L during the one hour.

[0057] Simultaneously control the temperature of the plating solution in the following manner:

[0058] Stage a: controlling the temperature of the plating solution to 75° C. within 5 hours of the start of electrochemical deposition;

[0059] Stage b: After stage a, the temperature of the plating solution is adjusted to 70° C. and maintained until the deposition is completed.

[0060] The first sample of the gradient structure nickel-copper-phosphorus alloy prepared in this embodiment is Figure 1 As shown in the figure, the grain size of the first sample gradually decreases from the micron level to the nanometer level from the surface to the inside, and there is no obvious macro interface. The coating quality is good and there are no obvious microcracks.

[0061] The cross-sectional distribution of copper and phosphorus content of the first sample of electrochemically deposited gradient structure nickel-copper-phosphorus alloy is shown in Figure 2. Figure 2 As shown in the figure, it can be seen that the atomic percentage of copper content gradually increases from 0 at% to about 12.5 at%, and the atomic percentage of phosphorus content gradually increases from 0 at% to about 1.1 at%. In this embodiment, the cross-sectional hardness value distribution of the first sample of the gradient structure nickel-copper-phosphorus alloy is referenced to Figure 3 As shown in the figure, it can be seen that its hardness gradually increases from about 2.0 GPa to about 6.5 GPa.

[0062] Example 2

[0063] This embodiment provides a method for preparing a gradient structure nickel-copper-phosphorus alloy, which includes the following steps:

[0064] (1) In this embodiment, a metal nickel plate with a purity of 99.6% is used as a consumable anode and a metal nickel plate is used as a cathode.

[0065] Prepare 1000ml of plating solution. The base plating solution contains the following chemical reagents at the following concentrations: 0.5mol / L NiSO4·6H2O, 20g / L NiCl2·6H2O, 30g / L H3BO3, and 0.5g / L CHNaOS. Weigh these chemicals using a scale and dissolve them in ultrapure water in a 1000ml beaker. Stir the solution with a magnetic stirrer until it becomes clear. Adjust the pH to 5.0±0.2 with dilute sulfuric acid or sodium hydroxide solution. Use a heater to maintain the initial bath temperature at 75±1°C.

[0066] (2) Use computer to control current density and additive concentration:

[0067] Current density: During the entire electrochemical deposition process, the current density remains constant at 30 mA / cm 2At the same time, the concentration of the additive saccharin sodium was regulated: starting from the start of electrochemical deposition, the concentration of saccharin sodium was kept constant at 0.5 g / L within the 5th hour after the start of electrochemical deposition, and then the saccharin sodium concentration increased from 0.5 g / L to 2 g / L within the 8th hour, and then the saccharin sodium concentration increased from 2 g / L to 4 g / L within the 12th hour, and then the saccharin sodium concentration increased from 4 g / L to 10 g / L within the 16th hour after that. Finally, the saccharin sodium concentration was maintained at 10 g / L for 1 hour to complete the electrochemical deposition.

[0068] At the same time, the concentration of the additive sodium hypophosphite was regulated: starting from the start of electrochemical deposition, the concentration of sodium hypophosphite was kept constant at 0 g / L within the 5th hour from the start of electrochemical deposition, and then the concentration of sodium hypophosphite increased from 0 g / L to 0.1 g / L within the 8th hour, and then the concentration of sodium hypophosphite increased from 0.1 g / L to 0.5 g / L within the 12th hour, and then the concentration of sodium hypophosphite gradually increased from 0.5 g / L to 1 g / L within the following 16 hours. Finally, the concentration of sodium hypophosphite was maintained at 1 g / L for 1 hour to complete the electrochemical deposition.

[0069] At the same time, the concentration of the additive copper sulfate was regulated: starting from the start of electrochemical deposition, the concentration of copper sulfate was kept constant at 0 g / L within the 5th hour from the start of electrochemical deposition, and then the concentration of copper sulfate increased from 0 g / L to 4 g / L within the 8th hour, and then the concentration of copper sulfate increased from 4 g / L to 10 g / L within the 12th hour, and then the concentration of copper sulfate increased from 10 g / L to 15 g / L within the 16th hour thereafter. Finally, the concentration of copper sulfate was maintained at 15 g / L for 1 hour to complete the electrochemical deposition.

[0070] At the same time, the concentration of the additive sodium citrate dihydrate was regulated: starting from the start of electrochemical deposition, the concentration of sodium citrate dihydrate was kept constant at 0 g / L within 5 hours from the start of electrochemical deposition, and then the concentration of sodium citrate dihydrate increased from 0 g / L to 60 g / L within 8 hours, and then the concentration of sodium citrate dihydrate increased from 60 g / L to 80 g / L within 12 hours, and then the concentration of sodium citrate dihydrate increased from 80 g / L to 120 g / L within 16 hours thereafter. Finally, the concentration of sodium citrate dihydrate was maintained at 120 g / L for 1 hour to complete the electrochemical deposition.

[0071] Simultaneously control the temperature of the plating solution in the following manner:

[0072] Stage a: controlling the temperature of the plating solution to be 75° C. within 5 hours after the start of electrochemical deposition;

[0073] Stage b: After stage a, the temperature of the plating solution is adjusted to 70° C. and maintained until the deposition is completed.

[0074] The second sample of the gradient structure nickel-copper-phosphorus alloy prepared in this embodiment is Figure 4 As shown, the grain size of the second sample gradually refines from micron to nanometer level, and there is no obvious macro interface. The coating quality is good and there is no obvious micro crack. The cross-sectional distribution of copper content and phosphorus content of the second sample of electrochemically deposited gradient structure nickel-copper-phosphorus alloy is shown in Figure 2. Figure 5 As shown in the figure, it can be seen that the atomic percentage of copper gradually increases from 0 at% to about 20 at%, and the atomic percentage of phosphorus gradually increases from 0 at% to about 3 at%. The cross-sectional hardness value distribution of the second sample of the gradient structure nickel-copper-phosphorus alloy is shown in the figure. Figure 6 As shown in the figure, it can be seen that the hardness gradually increases from 1.9 GPa to about 6.7 GPa.

[0075] Example 3

[0076] This embodiment provides a method for preparing a gradient structure nickel-copper-phosphorus alloy, which includes the following steps:

[0077] (1) In this embodiment, a metal nickel plate with a purity of 99.6% is used as a consumable anode and a metal nickel plate is used as a cathode.

[0078] Prepare 1000ml of plating solution. The base plating solution contains the following chemical reagents at the following concentrations: 0.3mol / L Ni(NH2SO3)2·4H2O, 20g / L NiCl2·6H2O, 30g / L H3BO3, and 0.5g / L CHNaOS. Weigh these chemicals using a balance and dissolve them in ultrapure water in a 1000ml beaker. Stir the solution with a magnetic stirrer until it becomes clear. Adjust the pH to 5.0±0.2 using dilute sulfuric acid or sodium hydroxide solution. Use a heater to maintain the initial bath temperature at 70±1°C.

[0079] (2) Use computer to control current density and additive concentration:

[0080] Current density: During the entire electrochemical deposition process, the current density remains constant at 50 mA / cm 2 At the same time, the concentration of the additive saccharin sodium was regulated: the concentration of saccharin sodium was kept constant at 0.5 g / L within 5 hours after the start of electrochemical deposition, and then the concentration of saccharin sodium increased from 0.5 g / L to 5 g / L within 8 hours, and then the concentration of saccharin sodium increased from 5 g / L to 10 g / L within 12 hours, and then the concentration of saccharin sodium increased from 10 g / L to 15 g / L within 16 hours after that. Finally, the concentration of saccharin sodium was maintained at 15 g / L for 1 hour to complete the electrochemical deposition.

[0081] At the same time, the concentration of the additive sodium hypophosphite was regulated: starting from the start of electrochemical deposition, the concentration of sodium hypophosphite was kept constant at 0 g / L from the start of electrochemical deposition to the 5th hour, and then the concentration of sodium hypophosphite increased from 0 g / L to 0.15 g / L within the 8th hour, and then the concentration of sodium hypophosphite increased from 0.15 g / L to 0.4 g / L within the 12th hour, and then the concentration of sodium hypophosphite increased from 0.4 g / L to 3.5 g / L within the 16th hour. Finally, the concentration of sodium hypophosphite was maintained at 3.5 g / L for one hour to complete the electrochemical deposition.

[0082] At the same time, the concentration of the additive copper sulfate was regulated: from the start of electrochemical deposition, the concentration of copper sulfate was kept constant at 0 g / L until the 5th hour, and then the concentration of copper sulfate increased from 0 g / L to 5 g / L within the 8th hour, and then the concentration of copper sulfate increased from 5 g / L to 12.5 g / L within the 12th hour, and then the concentration of copper sulfate increased from 12.5 g / L to 25 g / L within the following 16 hours. Finally, the concentration of copper sulfate was maintained at 25 g / L for one hour to complete the electrochemical deposition.

[0083] At the same time, the concentration of the additive sodium citrate dihydrate is regulated: from the start of electrochemical deposition, the concentration of sodium citrate dihydrate is kept constant at 0 g / L until the 5th hour, and then the concentration of sodium citrate dihydrate is increased from 0 g / L to 70 g / L within the 8th hour, and then the concentration of sodium citrate dihydrate is increased from 70 g / L to 110 g / L within the 12th hour, and then the concentration of sodium citrate dihydrate is increased from 110 g / L to 150 g / L within the 16th hour, and finally, the concentration of sodium citrate dihydrate is maintained at 150 g / L for one hour to complete the electrochemical deposition. At the same time, the temperature of the plating solution is maintained at 70°C.

[0084] The third sample of the gradient structure nickel-copper-phosphorus alloy prepared in this embodiment is Figure 7 As shown, the grain size of the third sample gradually refines from micron to nanometer level, and there is no obvious macro interface. The coating quality is good and there is no obvious micro crack. The cross-sectional distribution of copper content and phosphorus content of the third sample of electrochemically deposited gradient structure nickel-copper-phosphorus alloy is shown in Figure 2. Figure 8 As shown in the figure, it can be seen that the atomic percentage of copper content gradually increases from 0at% to about 35at%, and the atomic percentage of phosphorus content gradually increases from 0at% to about 6at%. The cross-sectional hardness value distribution of the gradient structure nickel-copper-phosphorus alloy is shown in the figure. Figure 9 As shown in the figure, it can be seen that the hardness gradually increases from 1.9 GPa to about 5.8 GPa.

[0085] At the same time, the anti-protein adhesion rate of the first, second and third samples of the gradient structure nickel-copper-phosphorus alloy and the weight loss rate after 48 hours of seawater scouring were respectively Figure 10 、 Figure 11 As shown in the two figures, GS Ni-Cu-P I refers to the first sample, GS Ni-Cu-P II refers to the second sample, and GS Ni-Cu-P III refers to the third sample. The first sample of the gradient nickel-copper-phosphorus alloy exhibits significantly higher protein adhesion resistance than 45-steel, while its weight loss after 48 hours of seawater scouring is lower than that of 45-steel. This indicates that both the first sample of the gradient nickel-copper-phosphorus alloy exhibits significantly better protein adhesion resistance and corrosion resistance than 45-steel. The second sample of the gradient nickel-copper-phosphorus alloy also exhibits significantly higher protein adhesion resistance than 45-steel and is comparable to the first sample of the gradient nickel-copper-phosphorus alloy. Furthermore, the second sample of the gradient nickel-copper-phosphorus alloy exhibits lower weight loss after 48 hours of seawater scouring than both 45-steel and the first sample of the gradient nickel-copper-phosphorus alloy, indicating that increasing the copper content further enhances the alloy's corrosion resistance. Compared to 45-steel, the first sample of the gradient nickel-copper-phosphorus alloy, and the second sample of the gradient nickel-copper-phosphorus alloy, the third sample of the gradient nickel-copper-phosphorus alloy exhibits significantly higher protein adhesion resistance. Furthermore, the weight loss rate of the third gradient nickel-copper-phosphorus alloy sample after 48 hours of seawater erosion was significantly lower than that of 45 steel, the first gradient nickel-copper-phosphorus alloy sample, and the second gradient nickel-copper-phosphorus alloy sample. This indicates that when the copper content exceeds approximately 30 atomic percent and the phosphorus content exceeds approximately 5 atomic percent, the gradient nickel-copper-phosphorus alloy can simultaneously exhibit excellent protein resistance and corrosion resistance.

[0086] Example 4

[0087] The substrate is pretreated before plating. The pretreatment includes mechanical grinding and polishing of the substrate and surface degreasing. Mechanical grinding is to use 200#, 400# and 800# sandpaper to polish the surface of the substrate in sequence. Surface degreasing is to use an organic solvent to clean the substrate surface. The organic solvent is acetone.

[0088] In this embodiment, the additives in the electroplating solution include copper salt, citrate, hypophosphite and sodium saccharin, and the current density is 200 mA / cm 2 scope.

[0089] The copper salt is copper sulfate, and the concentration of copper sulfate is controlled as follows: starting from the start of electrochemical deposition, the copper sulfate concentration is maintained at 0 until the 5.5th hour, and then the copper sulfate concentration is gradually increased until the copper sulfate concentration reaches 5 g / L within the 8.5th hour, and then the copper sulfate concentration is further gradually increased until the copper sulfate concentration reaches 7 g / L within the 12.5th hour, and the copper sulfate concentration is still further gradually increased until the copper sulfate concentration reaches 25 g / L within the 16.5th hour. The electrochemical deposition is continued by maintaining this concentration, and the electrochemical deposition takes half an hour to one hour to complete.

[0090] The hypophosphite is sodium hypophosphite, and the concentration of sodium hypophosphite is controlled as follows: from the start of electrochemical deposition, until the 5.5th hour, the concentration of sodium hypophosphite is maintained at 0, and then the concentration of sodium hypophosphite is gradually increased until the concentration of sodium hypophosphite reaches 0.12g / L within the 8.5th hour, and then the concentration of sodium hypophosphite is further gradually increased until the concentration of sodium hypophosphite reaches 0.4g / L within the 12.5th hour, and the concentration of sodium hypophosphite is still further gradually increased until the concentration of sodium hypophosphite reaches 5g / L within the 16.5th hour, and the electrochemical deposition is continued by maintaining this concentration, which takes half an hour to one hour to complete the electrochemical deposition.

[0091] The citrate is sodium citrate dihydrate or sodium citrate pentahydrate, and the concentration of sodium citrate dihydrate is controlled as follows: from the start of electrochemical deposition, until the 5.5th hour, the concentration of sodium citrate dihydrate is maintained at 0, and then the concentration of sodium citrate dihydrate is gradually increased until the concentration of sodium citrate dihydrate reaches 70g / L within the 8.5th hour, and then the concentration of sodium citrate dihydrate is further gradually increased until the concentration of sodium citrate dihydrate reaches 110g / L within the 12.5th hour, and the concentration of sodium citrate dihydrate is still further gradually increased until the concentration of sodium citrate dihydrate reaches 150g / L within the 16.5th hour, and the electrochemical deposition is continued by maintaining this concentration, and the electrochemical deposition takes half an hour to one hour to complete.

[0092] The concentration of saccharin sodium is controlled as follows: from the start of electrochemical deposition, the concentration of saccharin sodium is maintained at 0.5 g / L until the 5.5th hour, and then the concentration of saccharin sodium is gradually increased until the concentration of saccharin sodium reaches 5 g / L within the 8.5th hour, and then the concentration of saccharin sodium is further gradually increased until the concentration of saccharin sodium reaches 10 g / L within the 12.5th hour, and the concentration of saccharin sodium is still further gradually increased until the concentration of saccharin sodium reaches 15 g / L within the 16.5th hour, and the electrochemical deposition is continued while maintaining this concentration. It takes half an hour to one hour to complete the electrochemical deposition.

[0093] The components contained in the electrochemical deposition plating solution and the content of each component are as follows: nickel sulfate hexahydrate with a concentration of 0.2 mol / L, nickel chloride hexahydrate with a concentration of 20 g / L, boric acid with a concentration of 40 g / L, sodium tetraborate decahydrate with a concentration of 40 g / L, potassium sodium tartrate with a concentration of 10 g / L, sodium dodecylbenzenesulfonate with a concentration of 0.3 g / L, the plating solution pH is 5.0, and the plating solution temperature is 40°C.

[0094] Experimental testing revealed that the grain size of the nickel-copper-phosphorus alloy obtained in this embodiment gradually refined from 10 μm to 10 nm, with the grains becoming finer closer to the surface of the electroplated layer. The atomic percentages of copper and phosphorus in the gradient-structured nickel-copper-phosphorus alloy ranged from 5 to 15% and 1 to 10%, respectively, with the concentrations increasing closer to the surface.

[0095] Example 5

[0096] The substrate is pretreated before plating. The pretreatment includes mechanical grinding and polishing of the substrate and surface degreasing. Mechanical grinding is to use 200#, 400# and 800# sandpaper to polish the surface of the substrate in sequence. Surface degreasing is to use an organic solvent to clean the substrate surface. The organic solvent is ethanol.

[0097] In this embodiment, the additives in the electroplating solution include copper salt, citric acid, phosphorous acid and sodium saccharin, and the current density is from 20 to 25 mA / cm 2 Gradually changes to 80~85mA / cm 2 within the range.

[0098] The copper salt is copper sulfate, and the concentration of copper sulfate is controlled as follows: starting from the start of electrochemical deposition, the copper sulfate concentration is maintained at 0 until the 5.3th hour, and then the copper sulfate concentration is gradually increased until the copper sulfate concentration reaches 3 g / L within the 8.3th hour, and then the copper sulfate concentration is further gradually increased until the copper sulfate concentration reaches 12.5 g / L within the 12.3th hour, and the copper sulfate concentration is still further gradually increased until the copper sulfate concentration reaches 10 g / L within the 16.2th hour. The electrochemical deposition is continued by maintaining this concentration, and the electrochemical deposition takes half an hour to one hour to complete.

[0099] The concentration of phosphorous acid is controlled as follows: from the start of electrochemical deposition, the phosphorous acid concentration is maintained at 0 until the 5.3th hour, and then the concentration of phosphorous acid is gradually increased until the phosphorous acid concentration reaches 0.15 g / L within the 8.4th hour, and then the concentration of phosphorous acid is further gradually increased until the phosphorous acid concentration reaches 0.2 g / L within the 12.3th hour, and the concentration of phosphorous acid is still further gradually increased until the phosphorous acid concentration reaches 0.5 g / L within the 16.4th hour. The electrochemical deposition is continued by maintaining this concentration, and it takes half an hour to one hour to complete the electrochemical deposition.

[0100] The concentration of citric acid is controlled as follows: from the start of electrochemical deposition, the citric acid concentration is maintained at 0 until the 5.5th hour, and then the citric acid concentration is gradually increased until the citric acid concentration reaches 20 g / L within the 8.5th hour, and then the citric acid concentration is further gradually increased until the citric acid concentration reaches 50 g / L within the 12.1th hour, and the citric acid concentration is still further gradually increased until the citric acid concentration reaches 90 g / L within the 16.2th hour. The electrochemical deposition is continued by maintaining this concentration, and the electrochemical deposition takes half an hour to one hour to complete.

[0101] The concentration of saccharin sodium is controlled as follows: from the start of electrochemical deposition, the concentration of saccharin sodium is maintained at 0.5 g / L until the 5th hour, and then the concentration of saccharin sodium is gradually increased until the concentration of saccharin sodium reaches 2 g / L within the 8th hour, and then the concentration of saccharin sodium is further gradually increased until the concentration of saccharin sodium reaches 4 g / L within the 12.5th hour, and the concentration of saccharin sodium is still further gradually increased until the concentration of saccharin sodium reaches 5 g / L within the 16th hour. The electrochemical deposition is continued by maintaining this concentration, and it takes half an hour to one hour to complete the electrochemical deposition.

[0102] The components contained in the electrochemical deposition plating solution and the content of each component are as follows: nickel sulfate hexahydrate with a concentration of 0.5 mol / L, nickel chloride hexahydrate with a concentration of 10 g / L, boric acid with a concentration of 10 g / L, sodium dodecylbenzenesulfonate with a concentration of 0.6 g / L, the plating solution pH is 5.0±0.05, and the plating solution temperature is 80°C.

[0103] Experimental testing revealed that the grain size of the nickel-copper-phosphorus alloy obtained in this embodiment gradually decreased from 20 μm to 30 nm, with the grains becoming finer as they approached the surface of the electroplated layer. The atomic percentages of copper and phosphorus in the gradient-structured nickel-copper-phosphorus alloy ranged from 15 to 25% and 8 to 15%, respectively.

[0104] Example 6

[0105] The substrate is pretreated before plating. The pretreatment includes mechanical grinding and polishing of the substrate and surface degreasing. Mechanical grinding is to use 200#, 400# and 800# sandpaper to polish the surface of the substrate in sequence. Surface degreasing is to use an organic solvent to clean the substrate surface. The organic solvent is acetone.

[0106] In this embodiment, the additives in the electroplating solution include copper salt, citrate, hypophosphite, and sodium saccharin, and the current density is from 25 to 40 mA / cm 2 Gradually changes to 85~120mA / cm 2 within the range.

[0107] The copper salt is copper sulfate, and the concentration of copper sulfate is controlled as follows: starting from the start of electrochemical deposition, the copper sulfate concentration is maintained at 0 until the 5.5th hour, and then the copper sulfate concentration is gradually increased until the copper sulfate concentration reaches 4 g / L within the 8.5th hour, and then the copper sulfate concentration is further gradually increased until the copper sulfate concentration reaches 12 g / L within the 12.5th hour, and the copper sulfate concentration is still further gradually increased until the copper sulfate concentration reaches 20 g / L within the 16.5th hour. The electrochemical deposition is continued by maintaining this concentration, and the electrochemical deposition takes half an hour to one hour to complete.

[0108] The hypophosphite is sodium hypophosphite, and the concentration of sodium hypophosphite is controlled as follows: from the start of electrochemical deposition, until the 5.5th hour, the concentration of sodium hypophosphite is maintained at 0, and then the concentration of sodium hypophosphite is gradually increased until the concentration of sodium hypophosphite reaches 0.1g / L within the 8.5th hour, and then the concentration of sodium hypophosphite is further gradually increased until the concentration of sodium hypophosphite reaches 0.3g / L within the 12.5th hour, and the concentration of sodium hypophosphite is still further gradually increased until the concentration of sodium hypophosphite reaches 3g / L within the 16.5th hour, and the electrochemical deposition is continued by maintaining this concentration, which takes half an hour to one hour to complete the electrochemical deposition.

[0109] The citrate salt is sodium citrate pentahydrate, and the concentration of sodium citrate pentahydrate is controlled as follows: from the start of electrochemical deposition, until the 5.5th hour, the concentration of sodium citrate pentahydrate is maintained at 0, and then the concentration of sodium citrate pentahydrate is gradually increased until the concentration of sodium citrate pentahydrate reaches 50 g / L within the 8.5th hour, and then the concentration of sodium citrate pentahydrate is further gradually increased until the concentration of sodium citrate pentahydrate reaches 90 g / L within the 12.5th hour, and the concentration of sodium citrate pentahydrate is still further gradually increased until the concentration of sodium citrate pentahydrate reaches 130 g / L within the 16.5th hour. The electrochemical deposition is continued by maintaining this concentration, and the electrochemical deposition takes half an hour to one hour to complete.

[0110] The concentration of saccharin sodium is controlled as follows: from the start of electrochemical deposition, the concentration of saccharin sodium is maintained at 0.5 g / L until the 5.5th hour, and then the concentration of saccharin sodium is gradually increased until the concentration of saccharin sodium reaches 3 g / L within the 8.5th hour, and then the concentration of saccharin sodium is further gradually increased until the concentration of saccharin sodium reaches 8 g / L within the 12th hour, and the concentration of saccharin sodium is still further gradually increased until the concentration of saccharin sodium reaches 11 g / L within the 16.5th hour. The electrochemical deposition is continued by maintaining this concentration, and the electrochemical deposition takes half an hour to one hour to complete.

[0111] The components contained in the electrochemical deposition plating solution and the content of each component are as follows: nickel sulfate hexahydrate with a concentration of 0.4 mol / L, nickel chloride hexahydrate with a concentration of 15 g / L, boric acid with a concentration of 30 g / L, sodium tetraborate decahydrate with a concentration of 2 g / L, potassium sodium tartrate with a concentration of 1 g / L, and sodium dodecylbenzenesulfonate with a concentration of 0.4 g / L. The plating solution has a pH of 5.0±0.2 and a plating solution temperature of 65°C.

[0112] Experimental testing revealed that the grain size of the nickel-copper-phosphorus alloy obtained in this embodiment gradually decreased from 15 μm to 25 nm, with the grains becoming finer as they approached the surface of the electroplated layer. The atomic percentages of copper and phosphorus in the gradient-structured nickel-copper-phosphorus alloy ranged from 25 to 40% and 5 to 10%, respectively.

[0113] A structure with gradually changing copper and phosphorus contents is prepared in nickel-copper-phosphorus alloy, and the gradient distribution is precisely controllable, which can give full play to the unique performance advantages of each component material, greatly improving the overall performance and service performance of the material, and further bringing broader application prospects for nickel-based alloys.

[0114] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A gradient structure nickel-copper-phosphorus alloy, characterized in that: The grain size of the gradient structure nickel-copper-phosphorus alloy is gradually refined from 10 to 20 μm to 10 to 30 nm. The closer to the surface of the electroplating layer, the finer the grain. The copper content and phosphorus content of the copper-phosphorus ternary alloy change in a gradient at the same time. The atomic percentage ranges of copper and phosphorus in the gradient structure nickel-copper-phosphorus alloy are 5 to 40% and 1 to 15%, respectively. Using electrochemical deposition, nickel is used as the consumable anode. By controlling the current density and the concentration of additives in the electroplating solution, a gradient structure nickel-copper-phosphorus ternary alloy with both chemical composition gradient changes and grain size gradient changes is deposited under the action of direct current. The additive in the electroplating solution is selected from copper salt, citrate, hypophosphite, sodium saccharin, phosphorous acid and / or citric acid, Copper salt is used to provide copper element in nickel-copper-phosphorus alloy coating, hypophosphite is used to provide phosphorus element in coating, citric acid can be used to complex copper ions and nickel ions, saccharin sodium can be used to refine grains and optimize internal stress of coating, anode is selected from 99% pure nickel plate, cathode is selected from steel, titanium, copper and copper alloy or nickel, Current density is 20~200 mA / cm 2 range, or from 20 to 40 mA / cm 2 Gradually changes to 80~120 mA / cm 2 Within the range, The copper salt is copper sulfate, and the concentration of copper sulfate is controlled as follows: starting from the start of electrochemical deposition, Until the 5th to 5.5th hour, maintain the copper sulfate concentration at 0, and then gradually increase the copper sulfate concentration. Until the copper sulfate concentration reaches 3-5 g / L within 8-8.5 hours, then the copper sulfate concentration is further gradually increased. Until the concentration of copper sulfate reaches 7-12.5 g / L within 12-12.5 hours, the concentration of copper sulfate is further gradually increased. Until the concentration of copper sulfate reaches 10-25 g / L within 16-16.5 hours, the electrochemical deposition is continued while maintaining this concentration, and it takes half an hour to one hour to complete the electrochemical deposition.

2. The gradient structure nickel-copper-phosphorus alloy according to claim 1, characterized in that: The hypophosphite is sodium hypophosphite, and the concentration of sodium hypophosphite is controlled as follows: starting from the electrochemical deposition, Until the 5th to 5.5th hour, maintain the concentration of sodium hypophosphite at 0, and then gradually increase the concentration of sodium hypophosphite. Until the concentration of sodium hypophosphite reaches 0.05~0.15 g / L within 8~8.5 hours, then the concentration of sodium hypophosphite is further gradually increased. Until the concentration of sodium hypophosphite reaches 0.2~0.4 g / L within 12~12.5 hours, the concentration of sodium hypophosphite is further gradually increased. Until the concentration of sodium hypophosphite reaches 0.5-5 g / L within 16-16.5 hours, the electrochemical deposition is continued while maintaining this concentration, and it takes half an hour to one hour to complete the electrochemical deposition.

3. The gradient structure nickel-copper-phosphorus alloy according to claim 2, characterized in that: The citrate is sodium citrate dihydrate or sodium citrate pentahydrate, and the concentration of sodium citrate dihydrate is controlled as follows: starting from the start of electrochemical deposition, Until the 5th to 5.5th hour, maintain the concentration of sodium citrate dihydrate at 0, and then gradually increase the concentration of sodium citrate dihydrate. Until the concentration of sodium citrate dihydrate reaches 20-70 g / L within 8-8.5 hours, then the concentration of sodium citrate dihydrate is further gradually increased. Until the concentration of sodium citrate dihydrate reaches 50-110 g / L within 12-12.5 hours, the concentration of sodium citrate dihydrate is further gradually increased. Until the concentration of sodium citrate dihydrate reaches 90-150 g / L within 16-16.5 hours, the electrochemical deposition is continued while maintaining this concentration, and it takes half an hour to one hour to complete the electrochemical deposition.

4. The gradient structure nickel-copper-phosphorus alloy according to claim 3, characterized in that: The concentration of sodium saccharin is controlled as follows: starting from the start of electrochemical deposition, Until the 5th to 5.5th hour, maintain the concentration of saccharin sodium at 0.5g / L, then gradually increase the concentration of saccharin sodium. Until the concentration of saccharin sodium reaches 2-5 g / L within 8-8.5 hours, then the concentration of saccharin sodium is further gradually increased. Until the concentration of saccharin sodium reaches 4-10 g / L within 12-12.5 hours, the concentration of saccharin sodium is further gradually increased. Until the concentration of saccharin sodium reaches 5-15 g / L within 16-16.5 hours, the electrochemical deposition is continued while maintaining this concentration, and it takes half an hour to one hour to complete the electrochemical deposition.

5. The gradient structure nickel-copper-phosphorus alloy according to claim 4, characterized in that: The components of the electrochemical deposition bath and the content of each component are as follows: Nickel sulfate hexahydrate or nickel sulfamate tetrahydrate at a concentration of 0.2-0.5 mol / L, nickel chloride hexahydrate at a concentration of 10-20 g / L, boric acid at a concentration of 10-40 g / L, sodium tetraborate decahydrate at a concentration of 0-40 g / L, potassium sodium tartrate at a concentration of 0-10 g / L, sodium dodecylbenzenesulfonate at a concentration of 0.3-0.6 g / L, and the plating solution pH is 5.0 ± 0.

2. The bath temperature is 70 ~ 75 ℃, and the bath temperature is controlled as follows: The first stage: control the temperature of the plating solution to 75±1℃ within 5~5.5 hours after the start of electrochemical deposition. Stage 2: After the first stage, the temperature of the plating solution is adjusted to 70±1°C and maintained until the deposition is completed.

6. The gradient structure nickel-copper-phosphorus alloy according to claim 5, characterized in that: The substrate is pretreated before plating. The pretreatment includes mechanical grinding and polishing of the substrate and surface degreasing. Mechanical grinding is to polish the surface of the substrate with 200#, 400# and 800# sandpaper in sequence. Surface degreasing is to clean the surface of the substrate with an organic solvent. The organic solvent is acetone and / or ethanol.

Images