Method for plating nickel and cobalt on steel by combining direct current and pulse electrodeposition

Abstract

The invention relates to the technical field of steel material surface protection, in particular to a method for plating nickel and cobalt on steel by combining direct current and pulse electrodeposition. Comprising the following steps: removing oil from a steel strip by adopting an electrochemical method to obtain an oil-removed steel strip; the oil-removed steel strip is activated, an oxide film on the surface of the base material steel strip is removed, and the pretreated steel strip is obtained; pre-plating a nickel plating layer on the pretreated steel strip by adopting direct-current electrodeposition; and plating a nickel-cobalt alloy layer on the nickel plating layer by adopting pulse electrodeposition. The nickel-plated cobalt steel strip prepared through the method has high corrosion resistance and punch forming capacity, the production efficiency is improved, and the industrial production requirement is met.

Description

Technical Field

[0001] The invention relates to the technical field of steel material surface protection, and in particular to a method for plating steel with nickel and cobalt by combining direct current and pulse electrodeposition. Background Art

[0002] Nickel has excellent ferromagnetism, ductility, wear resistance, corrosion resistance and other characteristics. For a long time, the battery steel shell has mainly adopted the method of nickel coating to improve the rust resistance and conductivity of the battery steel shell. The process of depositing metal or alloy on the cathode surface by electrolysis is mainly divided into three steps: liquid phase mass transfer, charged particles gather near the cathode under the action of an external electric field; electron transfer, charged particles obtain electrons on the cathode surface; electrocrystallization, generating a new phase at the cathode. The similar deposition potential of the two metal elements of nickel and cobalt is the basis for their co-deposition. Although nickel-plated steel strip has good corrosion resistance, its corrosion resistance will be affected to a certain extent under special conditions such as high temperature and high humidity. This is because the nickel plating layer may undergo chemical or physical changes in these extreme environments, resulting in a decrease in protective performance. Therefore, in application scenarios that require long-term exposure to high temperature and high humidity environments, the corrosion resistance of nickel-plated steel strips may not meet the requirements.

[0003] Chinese invention patent CN110184574B discloses a treatment process for improving the adhesion of coating on the surface of steel, which specifically includes the following treatment steps: 1) cleaning treatment of the steel surface, 2) coating treatment of the steel surface, and 3) pulse electrodeposition treatment of the steel surface. The invention significantly improves the surface properties of the steel and increases the roughness of the steel surface by performing a special nickel plating treatment method on the steel surface, thereby improving the adhesion of the steel surface and enhancing the firmness of the combination of the coating and the steel. However, the corrosion resistance of the nickel plating layer will be affected to a certain extent under conditions of high temperature and high humidity. Summary of the invention

[0004] The present invention provides a method for plating nickel and cobalt on steel by combining direct current and pulse electrodeposition, comprising the following steps:

[0005] The steel strip is degreased by an electrochemical method to obtain a degreased steel strip;

[0006] The degreased steel strip is activated to remove the oxide film on the surface of the base steel strip to obtain a pretreated steel strip;

[0007] Pre-plating a nickel coating on the pre-treated steel strip by direct current deposition;

[0008] A nickel-cobalt alloy layer is plated on the nickel-plated layer by pulse electrodeposition.

[0009] The degreasing temperature is 55-60°C and the pH is 9-11.

[0010] Preferably, the degreasing temperature is 55-60°C and the pH is 10.

[0011] The degreasing solution comprises: 50-90 g / L sodium hydroxide, 30-50 g / L sodium carbonate, 20-30 g / L sodium phosphate and 8-15 g / L sodium silicate, and the solvent is deionized water.

[0012] Preferably, the degreasing solution components include: 60-90 g / L sodium hydroxide, 40-50 g / L sodium carbonate, 25-30 g / L sodium phosphate and 8-12 g / L sodium silicate, and the solvent is deionized water.

[0013] The activation is carried out using a dilute sulfuric acid aqueous solution with a volume fraction of 10-20% for 1-5 minutes.

[0014] Preferably, the activation is performed using a dilute sulfuric acid aqueous solution with a volume fraction of 11-18% for 1-3 minutes.

[0015] The current density of the pulse electrodeposition is 3-10A / dm 2 .

[0016] Preferably, the current density of the pulse electrodeposition is 5-10A / dm 2 .

[0017] The temperature of the pulse electrodeposition is 30-50°C.

[0018] Preferably, the temperature of the pulse electrodeposition is 40-50°C.

[0019] The electroplating solution used in the pulse electrodeposition includes cobalt sulfate (CoSO4·7H2O), and the content of cobalt sulfate in the electroplating solution is 7-15 g / L.

[0020] Preferably, the electroplating solution used for the pulse electrodeposition includes cobalt sulfate, and the content of cobalt sulfate in the electroplating solution is 7-10 g / L.

[0021] The applicant has found that the current density of pulse electrodeposition is 5-10A / dm 2 The temperature is 30-50℃, which can improve the corrosion resistance of the battery steel shell, which is beneficial to the transportation and long-term storage of the battery steel shell and battery products. It may be that the specific current density effectively reduces the porosity of the coating surface, achieves the effect of sealing the pores, and protects the substrate from corrosion. At the same time, the specific temperature prevents the hydrogen bubbles generated by electrodeposition from being retained on the surface of the plated part, or the presence of non-conductive parts on the surface of the plated part, avoiding the inability of nickel ions to deposit, resulting in a large porosity on the surface.

[0022] The pH value of the electroplating solution used in the pulse electrodeposition is 2-6.

[0023] Preferably, the pH value of the plating solution used in the pulse electrodeposition is 2-5.

[0024] The electroplating solution used in the pulse electrodeposition also includes 200-280 g / L nickel sulfate (NiSO4·7H2O), 30-80 g / L nickel chloride (NiCl2·6H2O), 20-35 g / L boric acid and 3-15 g / L additives, and the solvent used in the electroplating solution is deionized water.

[0025] Preferably, the electroplating solution used in the pulse electrodeposition also includes 220-280 g / L nickel sulfate (NiSO4·7H2O), 40-80 g / L nickel chloride (NiCl2·6H2O), 25-35 g / L boric acid and 5-15 g / L additives, and the solvent used in the electroplating solution is deionized water.

[0026] The additives include a cylinder opening agent, a brightening agent, a current adjusting agent, and a wetting agent.

[0027] The electroplating solution used in the direct current electrodeposition comprises: 120-220 g / L nickel sulfate, 5-10 g / L nickel chloride and 20-40 g / L boric acid, and the solvent used in the electroplating solution is deionized water.

[0028] Preferably, the components of the electroplating solution used in the direct current electrodeposition include: 150-220 g / L nickel sulfate, 5-8 g / L nickel chloride and 20-35 g / L boric acid, and the solvent used in the electroplating solution is deionized water.

[0029] The current density of the DC electrodeposition is 1-5A / dm 2 .

[0030] Preferably, the current density of the DC electrodeposition is 3-5A / dm 2 .

[0031] The temperature of the direct current electrodeposition is 25-35°C.

[0032] Preferably, the temperature of the direct current deposition is 30-35°C.

[0033] The pH value of the electroplating solution used in the direct current electrodeposition is 3-7.

[0034] Preferably, the pH value of the electroplating solution used in the direct current electrodeposition is 4-6.

[0035] Beneficial Effects

[0036] 1. Pre-plating a layer of nickel on the pre-treated steel strip by direct current deposition can improve the bonding strength between the coating and the substrate.

[0037] 2. Pulse electrodeposition is used to coat a layer of nickel-cobalt alloy on the pre-nickel-plated steel strip, which can improve the electrical conductivity, reduce the contact resistance of the battery casing, and improve and enhance the discharge performance of the battery.

[0038] 3. The current density of pulse electrodeposition is 5-10A / dm 2 And the temperature is 30-50℃, which can improve the corrosion resistance of the battery steel shell, and is beneficial to the transportation and long-term storage of the battery steel shell and battery products.

[0039] 4. The electroplating solution used in pulse electrodeposition includes cobalt sulfate, and the content of cobalt sulfate in the electroplating solution is 7-15 g / L, which can improve the wear resistance and pulverization performance of the steel strip.

[0040] 5. The pH value of the plating solution used for DC electrodeposition is 3-7, and the pH value of the plating solution used for pulse electrodeposition is 2-6, which can improve the stamping forming ability, further improve production efficiency, and meet industrial production needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is the surface morphology of the nickel-cobalt plated steel strip prepared in Example 1 after a 56-hour salt spray test.

[0042] Figure 2 This is the surface morphology of the nickel-cobalt plated steel strip prepared in Example 2 after a 56-hour salt spray test.

[0043] Figure 3 This is the surface morphology of the nickel-cobalt plated steel strip prepared in Example 3 after a 56-hour salt spray test.

[0044] Figure 4 This is the surface morphology of the nickel-cobalt plated steel strip prepared in Example 4 after a 56-hour salt spray test.

[0045] Figure 5 This is the surface morphology of the nickel-cobalt plated steel strip prepared in Example 5 after a 56-hour salt spray test.

[0046] Figure 6 This is the surface morphology of the nickel-cobalt plated steel strip prepared in Comparative Example 1 after an 8-hour salt spray test.

[0047] Figure 7 This is the surface morphology of the nickel-cobalt plated steel strip prepared in Comparative Example 2 after an 8-hour salt spray test.

[0048] Figure 8 This is the surface morphology of the nickel-cobalt plated steel strip prepared in Comparative Example 3 after a 48-hour salt spray test.

[0049] Fig. 9 This is the surface morphology of the nickel-cobalt plated steel strip prepared in Comparative Example 4 after a 48-hour salt spray test.

[0050] Fig.10 This is the surface morphology of the nickel-cobalt plated steel strip prepared in Comparative Example 5 after a 56-hour salt spray test.

[0051] Fig.11 This is the surface morphology of the nickel-cobalt plated steel strip prepared in Comparative Example 6 after a 56-hour salt spray test. DETAILED DESCRIPTION

[0052] Example 1

[0053] A method for plating nickel and cobalt on steel by combining direct current and pulse electrodeposition, comprising the following steps:

[0054] S1, degreasing the steel strip using an electrochemical method;

[0055] S2, removing the oxide film on the surface of the base steel strip by activation treatment;

[0056] S3, pre-plating a nickel coating on the pre-treated steel strip by direct current electrodeposition, the anode being a nickel plate;

[0057] S4, using pulse electrodeposition to plate a nickel-cobalt alloy layer on the pre-nickel plated steel strip, the anode is a nickel-cobalt alloy plate, and the prepared nickel-cobalt plated steel strip is cleaned and dried.

[0058] The degreasing temperature is 55° C., the pH is 10, the degreasing solution components include: 70 g / L sodium hydroxide, 40 g / L sodium carbonate, 25 g / L sodium phosphate and 10 g / L sodium silicate, and the solvent is deionized water.

[0059] The activation was performed using a 15% by volume aqueous solution of dilute sulfuric acid for 2 minutes.

[0060] The pH value of the electroplating solution used in the pulse electrodeposition is 5.

[0061] The electroplating solution used in the pulse electrodeposition also includes 240g / L nickel sulfate (NiSO4·7H2O), 55g / L nickel chloride (NiCl2·6H2O), 30g / L boric acid and 8g / L additives. The solvent used in the electroplating solution is deionized water. The additives are 5g / L opener, 1g / L brightener, 0.2g / L current regulator and 1.8g / L wetting agent, which are purchased from Atotech China Chemical Co., Ltd.

[0062] The components of the electroplating solution used for the DC electrodeposition include: 180g / L nickel sulfate, 7g / L nickel chloride and 30g / L boric acid, the solvent used for the electroplating solution is deionized water, the current density of the DC electrodeposition is 3A / dm2, the temperature of the DC electrodeposition is 32°C, and the pH value of the electroplating solution used for the DC electrodeposition is 5.

[0063] The current density of the pulse electrodeposition is 5A / dm 2 .

[0064] The temperature of the pulse electrodeposition was 30°C.

[0065] The electroplating solution used in the pulse electrodeposition includes cobalt sulfate (CoSO4·7H2O), and the content of cobalt sulfate in the electroplating solution is 7 g / L.

[0066] Example 2

[0067] The specific implementation method is the same as that of Example 1; except that the current density of the pulse electrodeposition in Example 2 is 10 A / dm 2 .

[0068] Example 3

[0069] Specific implementation method is the same as Example 1; the difference is that the temperature of pulse electrodeposition in Example 3 is 35°C.

[0070] Example 4

[0071] Specific implementation method is the same as that of Example 1; the difference is that the temperature of the pulse electrodeposition in Example 4 is 40°C.

[0072] Example 5

[0073] The specific implementation is the same as that of Example 1; the difference is that the content of cobalt sulfate in the electroplating solution in Example 5 is 9 g / L.

[0074] Comparative Example 1

[0075] The specific implementation method is the same as that of Example 1; except that the current density of the pulse electrodeposition in Comparative Example 1 is 1 A / dm 2 .

[0076] Comparative Example 2

[0077] The specific implementation method is the same as that of Example 1; except that the current density of the pulse electrodeposition in Comparative Example 2 is 3A / dm 2 .

[0078] Comparative Example 3

[0079] Specific implementation method is the same as Example 1; the difference is that the temperature of pulse electrodeposition in Comparative Example 3 is 20°C.

[0080] Comparative Example 4

[0081] Specific implementation method is the same as Example 1; the difference is that the temperature of pulse electrodeposition in Comparative Example 4 is 25°C.

[0082] Comparative Example 5

[0083] The specific implementation is the same as Example 1; the difference is that the content of cobalt sulfate in the electroplating solution in Comparative Example 5 is 3 g / L.

[0084] Comparative Example 6

[0085] The specific implementation is the same as Example 1; the difference is that the content of cobalt sulfate in the electroplating solution in Comparative Example 6 is 5 g / L.

[0086] Performance testing methods and data

[0087] The nickel-cobalt plated steel strips prepared in the examples and comparative examples were subjected to a neutral salt spray test (NSS) at a temperature of 35° C. and a 5 wt % sodium chloride aqueous solution for 56 hours, with observations made every 8 hours.

[0088] like Figure 1-5 As shown, none of Examples 1-5 showed corrosion, while Comparative Examples 1-6 ( Figure 6-11 ) showed corrosion to varying degrees.

Claims

1. A method for nickel-cobalt plating of steel by combining direct current and pulse electrodeposition, characterized in that: The following steps are involved: The steel strip is degreased by an electrochemical method to obtain a degreased steel strip; The degreased steel strip is activated to remove the oxide film on the surface of the base steel strip to obtain a pretreated steel strip; Pre-plating a nickel coating on the pre-treated steel strip by direct current deposition; A nickel-cobalt alloy layer is plated on the nickel-plated layer by pulse electrodeposition.

2. The method for nickel-cobalt plating of steel by combining direct current and pulse electrodeposition according to claim 1, characterized in that: The current density of the pulse electrodeposition is 5-10A / dm 2 .

3. The method for nickel-cobalt plating of steel by combining direct current and pulse electrodeposition according to claim 1 or 2, characterized in that: The temperature of the pulse electrodeposition is 30-50°C.

4. The method for nickel-cobalt plating of steel by combining direct current and pulse electrodeposition according to claim 3, characterized in that: The electroplating solution used in the pulse electrodeposition includes cobalt sulfate, and the content of cobalt sulfate in the electroplating solution is 7-15 g / L.

5. The method for nickel-cobalt plating of steel by combining direct current and pulse electrodeposition according to claim 4, characterized in that: The pH value of the electroplating solution used in the pulse electrodeposition is 2-6.

6. The method for nickel-cobalt plating of steel by combining direct current and pulse electrodeposition according to claim 5, characterized in that: The electroplating solution used in the pulse electrodeposition also includes 200-280 g / L nickel sulfate, 30-80 g / L nickel chloride, 20-35 g / L boric acid and 3-15 g / L additives, and the solvent used in the electroplating solution is deionized water.

7. The method for nickel-cobalt plating of steel by combining direct current and pulse electrodeposition according to claim 6, characterized in that: The additives include a cylinder opening agent, a brightening agent, a current adjusting agent, and a wetting agent.

8. The method for nickel-cobalt plating of steel by combining direct current and pulse electrodeposition according to claim 7, characterized in that: The components of the electroplating solution used in the direct current electrodeposition include: 120-220 g / L nickel sulfate, 5-10 g / L nickel chloride and 20-40 g / L boric acid, and the solvent used in the electroplating solution is deionized water.

9. The method for nickel-cobalt plating of steel by combining direct current and pulse electrodeposition according to claim 8, characterized in that: The current density of the DC electrodeposition is 1-5A / dm 2 .

10. The method for nickel-cobalt plating of steel by combining direct current and pulse electrodeposition according to claim 9, characterized in that: The temperature of the direct current electrodeposition is 25-35°C.

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