Method for improving corrosion resistance of amorphous Ni-Cu-P coating

Abstract

The invention provides a method for improving the corrosion resistance of an amorphous Ni-Cu-P coating, which comprises the following steps: polishing, grinding, cleaning and drying a metal substrate to obtain a metal substrate to be coated; mixing nickel sulfate hexahydrate, nickel acetate tetrahydrate, copper sulfate pentahydrate, trisodium citrate dihydrate, potassium sodium tartrate tetrahydrate, lauryl sodium sulfate, ammonium acetate and sodium hypophosphite, and adjusting the pH value to obtain a plating solution; and the plating solution is put into a constant-temperature heater, a to-be-plated metal substrate serves as a cathode, a Ni sheet serves as an anode, the to-be-plated metal substrate and the Ni sheet are put into the plating solution, the voltage of a power source is adjusted, energization activation and chemical plating are conducted, and the metal substrate with the amorphous Ni-Cu-P plating layer is obtained. The amorphous Ni-Cu-P plating layer has an obvious passivation phenomenon in a 3.5% NaCl solution, and is excellent in corrosion resistance.

Description

Technical Field

[0001] This invention relates to the field of surface treatment technology, and in particular to a method for improving the corrosion resistance of amorphous Ni-Cu-P coatings. Background Technology

[0002] Because electroless plating requires no power source, consumes little energy, and the plating layer is obtained through an autocatalytic reaction within the workpiece itself, resulting in better adhesion, uniform thickness, and good conformability, electroless plating technology is widely used in surface treatment of parts across various fields.

[0003] Stainless steel boasts excellent properties and is used in many fields. However, micro-scratches on the surface of stainless steel can form corrosion micro-cells, accelerating corrosion. If stainless steel workpieces are used in coastal areas, the humid climate and the corrosive effects of seawater chloride ions will accelerate aging and eventual failure. Carbon steel has even worse corrosion resistance than stainless steel. Therefore, surface treatments are necessary for both stainless steel and carbon steel to enhance their corrosion resistance.

[0004] Amorphous Ni-P coatings are widely used in many fields such as chemical engineering, machinery, and aerospace due to their excellent corrosion resistance. However, with the development of technology, many fields have placed higher demands on the performance of Ni-P. In order to obtain alloy coatings with stronger corrosion resistance, this paper upgrades and modifies the electroless Ni-P plating process, and studies and prepares amorphous Ni-Cu-P coatings with excellent corrosion resistance.

[0005] CN 117286480 A discloses a chemical plating process for preparing a Ni-Cu-P amorphous alloy coating as a diffusion barrier layer at the solder interface of electronic packaging. Since the Ni-Cu-P amorphous alloy coating has poor corrosion resistance, a method is provided to improve the corrosion resistance of the amorphous Ni-Cu-P coating. Summary of the Invention

[0006] The present invention aims to provide an amorphous Ni-Cu-P coating with excellent corrosion resistance, and the technical solution is as follows: (1) Preparation of plating solution: The main salt (nickel sulfate hexahydrate + nickel acetate tetrahydrate), copper sulfate pentahydrate, trisodium citrate dihydrate + potassium sodium tartrate tetrahydrate), sodium dodecyl sulfate, ammonium acetate and sodium hypophosphite are mixed in sequence and water is added and stirred evenly. Then the pH value is adjusted to 6-7.

[0007] (2) Activation before electroless plating: Before electroless plating, the metal substrate to be plated is pre-electro-activated, that is, the substrate is used as the cathode and the Ni sheet is used as the anode. The cathode and anode are placed in the electroless plating solution in parallel and activated by electricity. The electro-activation process parameters are: voltage 0.5V-4V and time 1s-10s. (3) The obtained Ni-Cu-P coating: The composition of the amorphous Ni-Cu-P alloy coating is Ni: 55%-93%, Cu: 2%-20%, P: 5%-25% by atomic percentage, and the coating thickness is 1-50μm.

[0008] According to one aspect of the present invention, a method for improving the corrosion resistance of amorphous Ni-Cu-P coatings is provided. The method includes the following steps: polishing and grinding a metal substrate, cleaning and drying it to obtain a metal substrate to be plated; mixing nickel sulfate hexahydrate, nickel acetate tetrahydrate, copper sulfate pentahydrate, trisodium citrate dihydrate, potassium sodium tartrate tetrahydrate, sodium dodecyl sulfate, ammonium acetate, and sodium hypophosphite, and adjusting the pH to obtain a plating solution; placing the plating solution in a constant temperature heater, using the metal substrate to be plated as the cathode and a Ni sheet as the anode, immersing it in the plating solution, adjusting the power supply voltage, activating it by energizing, and performing chemical plating to obtain a metal substrate with an amorphous Ni-Cu-P coating.

[0009] Furthermore, the metal substrate is a 20# steel substrate; The plating solution specifically comprises 10-50 g / L nickel sulfate hexahydrate, 1-10 g / L nickel acetate tetrahydrate, 0.01-4 g / L copper sulfate pentahydrate, 20-50 g / L trisodium citrate dihydrate, 1-20 g / L potassium sodium tartrate tetrahydrate, 0.1-1.5 g / L sodium dodecyl sulfate, 20-60 g / L ammonium acetate, and 10-45 g / L sodium hypophosphite, with a pH of 6-7.

[0010] Furthermore, the heating temperature of the constant temperature heater is 60-70℃; The power supply voltage is 0.5-4V, and the power-on activation time is 1s-10s.

[0011] Furthermore, the duration of the electroless plating is 0.2 to 4 hours.

[0012] Furthermore, the metal substrate of the amorphous Ni-Cu-P coating has a coating composition of Ni: 55%-93%, Cu: 2%-20%, and P: 5%-25%, by atomic percentage. The thickness of the amorphous Ni-Cu-P coating is 1-50 μm.

[0013] Furthermore, in a 3.5% NaCl aqueous solution, the amorphous Ni-Cu-P coating exhibited a significant passivation zone within a voltage range of -0.537 to -0.345 V, demonstrating excellent corrosion resistance.

[0014] Furthermore, the amorphous Ni-Cu-P coating is microscopically smooth, dense, and free of obvious pores.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The Ni-Cu-P / 20# steel obtained by the technical solution disclosed in this invention showed obvious passivation in 3.5% NaCl solution (that is, obvious passivation zone appeared in the voltage range of -0.537~-0.345V), and had excellent corrosion resistance. However, the bare steel sheet did not show passivation in 3.5% NaCl solution and had poor corrosion resistance.

[0016] (2) The amorphous Ni-Cu-P coating obtained by the technical solution disclosed in this invention has a smooth and dense surface without pores. The preparation process involves chemical plating at a temperature of about 60-70℃, which has low energy consumption, simple operation, and good activation effect. Attached Figure Description

[0017] Figure 1 This is a SEM image of the Ni-Cu-P / 20# steel prepared in Example 1 of the present invention; Figure 2 The image shows the XRD pattern of the amorphous Ni-Cu-P coating on Ni-Cu-P / 20# steel prepared in Example 1 of this invention. Figure 3 The graph shows the corrosion test results of the Ni-Cu-P / 20# steel described in the application example of this invention. Detailed Implementation

[0018] The present invention will be further described below with reference to specific embodiments, but this does not limit the present invention in any way.

[0019] Unless otherwise specified, the reagents used in the embodiments, comparative examples, and application examples of this invention were all obtained through purchase.

[0020] The present invention provides a method for improving the corrosion resistance of amorphous Ni-Cu-P coatings in the specific embodiments section, the method comprising the following steps: Step 1, Pretreatment: After polishing the metal substrate to be plated, ultrasonically clean it and blow it dry for later use.

[0021] Step 2: Prepare the plating solution: nickel sulfate hexahydrate 10-50 g / L, nickel acetate tetrahydrate 1-10 g / L, copper sulfate pentahydrate 0.01-4 g / L, trisodium citrate dihydrate 20-50 g / L, potassium sodium tartrate tetrahydrate 1-20 g / L, sodium dodecyl sulfate 0.1-1.5 g / L, ammonium acetate 20-60 g / L, sodium hypophosphite 10-45 g / L, and adjust the pH to 6-7.

[0022] Step 3: Place the plating solution into a constant temperature heater and control the temperature at 60-70℃; place the cleaned metal substrate as the cathode and the Ni sheet as the anode into the plating solution. Set the power supply voltage to 0.5-4V and activate for 1-10 seconds.

[0023] Step 4, the electroless plating duration is 0.2~4h.

[0024] Example 1 Step 1, Pretreatment: After grinding and polishing the metal substrate (20# steel substrate) to be plated, ultrasonically clean it and blow it dry for later use.

[0025] Step 2, prepare the plating solution: nickel sulfate hexahydrate 40 g / L, nickel acetate tetrahydrate 10 g / L, copper sulfate pentahydrate 2 g / L, trisodium citrate dihydrate 50 g / L, potassium sodium tartrate tetrahydrate 10 g / L, sodium dodecyl sulfate 0.1 g / L, ammonium acetate 40 g / L, sodium hypophosphite 25 g / L, and adjust the pH to 6.

[0026] Step 3: Place the plating solution into a constant temperature heater and control the temperature at 60℃. Place the cleaned Cu plate as the cathode and the Ni sheet as the anode into the plating solution. Set the power supply voltage to 0.5V and activate for 1 second.

[0027] Step 4, chemical plating duration 0.5 h, to obtain Ni-Cu-P / 20# steel. The SEM image of the amorphous Ni-Cu-P coating surface of the Ni-Cu-P / 20# steel is shown below. Figure 1 As shown, the coating surface is smooth and dense, without pores. The XRD pattern of the amorphous Ni-Cu-P coating is as follows. Figure 2 As shown.

[0028] Example 2 The difference from Example 1 is that the copper sulfate pentahydrate in step 2 is 2 g / L, while the rest of the steps are the same as in Example 1, and the surface of the resulting amorphous Ni-Cu-P coating is still smooth.

[0029] Application examples The Ni-Cu-P / 20# steel prepared in Example 1 was placed in a 3.5% NaCl solution for potentiodynamic scanning to test its corrosion resistance. The polarization curve is shown below. Figure 3 As shown, the prepared Ni-Cu-P / 20# steel exhibited obvious passivation in 3.5% NaCl solution, with the passivation zone appearing in the range of -0.537 to -0.345V, demonstrating excellent corrosion resistance.

[0030] The above description is merely a few embodiments of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any modifications or alterations made by those skilled in the art without departing from the scope of the technical solution of the present invention using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for improving the corrosion resistance of amorphous Ni-Cu-P coatings, characterized in that, The method includes the following steps: polishing and grinding the metal substrate, cleaning and drying it to obtain the metal substrate to be plated; mixing nickel sulfate hexahydrate, nickel acetate tetrahydrate, copper sulfate pentahydrate, trisodium citrate dihydrate, potassium sodium tartrate tetrahydrate, sodium dodecyl sulfate, ammonium acetate, and sodium hypophosphite, and adjusting the pH to obtain a plating solution; placing the plating solution in a constant temperature heater, using the metal substrate to be plated as the cathode and the Ni sheet as the anode, immersing it in the plating solution, adjusting the power supply voltage, activating it with electricity, and performing chemical plating to obtain a metal substrate with an amorphous Ni-Cu-P coating.

2. The method according to claim 1, characterized in that, The metal substrate is a 20# steel substrate; The plating solution specifically comprises 10-50 g / L nickel sulfate hexahydrate, 1-10 g / L nickel acetate tetrahydrate, 0.01-4 g / L copper sulfate pentahydrate, 20-50 g / L trisodium citrate dihydrate, 1-20 g / L potassium sodium tartrate tetrahydrate, 0.1-1.5 g / L sodium dodecyl sulfate, 20-60 g / L ammonium acetate, and 10-45 g / L sodium hypophosphite, with a pH of 6-7.

3. The method according to claim 1, characterized in that, The heating temperature of the constant temperature heater is 60-70℃; The power supply voltage is 0.5-4V, and the power-on activation time is 1s-10s.

4. The method according to claim 1, characterized in that, The duration of the electroless plating is 0.2 to 4 hours.

5. The method according to claim 1, characterized in that, The metal substrate of the amorphous Ni-Cu-P coating has a coating composition of Ni: 55%-93%, Cu: 2%-20%, P: 5%-25%, by atomic percentage. The thickness of the amorphous Ni-Cu-P coating is 1-50 μm.

6. The method according to claim 1, characterized in that, In a 3.5% NaCl aqueous solution, the amorphous Ni-Cu-P coating exhibited a significant passivation zone within a voltage range of -0.537 to -0.345 V, demonstrating excellent corrosion resistance.

7. The method according to claim 1, characterized in that, The amorphous Ni-Cu-P coating is microscopically smooth, dense, and free of obvious pores.

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