Method for plating Fe-Co-Ni film by adopting double reference electrodes

Abstract

The invention discloses a method for plating a Fe-Co-Ni film by adopting double reference electrodes. The method comprises the following steps: S1, adding choline chloride, levulinic acid and water into a Harlin tank, and then adding chlorides of Fe, Co and Ni to obtain an electro-deposition solution; s2, respectively connecting the copper sheet and the platinum sheet with two electrodes of a power supply, and respectively grounding the two reference electrodes of the same type; and S3, an electrodeposition experiment is conducted through cyclic voltammetry, and the Fe-Co-Ni thin film is obtained on the copper sheet. According to the invention, the potential difference of the two reference electrodes is used as the reference potential, the fluctuation is extremely small (below 0.001 V), and the working potential difference can be regulated and controlled very accurately, so that side reactions possibly occurring in the battery can be accurately reduced, and a stable and reliable reference potential can be provided to ensure that the working environment of the battery is stable and the service life of the battery is prolonged. Therefore, the unexpected reaction in the electrochemical reaction is minimized.

Description

Technical Field

[0001] The invention relates to a method for plating a Fe-Co-Ni film by adopting double reference electrodes, and belongs to the field of electrochemical deposition. Background Art

[0002] There are many coating technologies that form thin films on the surface of substrate materials to improve the performance of the surface, but traditional methods such as vacuum evaporation, sputtering and ion plating have shortcomings such as high cost, difficult operation and poor coating quality. The electrochemical deposition method has simple equipment, easy to control operating conditions, a wide range of coating materials, and low cost, and is widely used in industry. Fe, Co, and Ni are three common magnetic metals, and their alloys exhibit excellent magnetic properties, including low hysteresis loss and significant magnetic anisotropy. Therefore, they are widely used in the manufacture of various magnetic devices. In addition to having good magnetic properties, the manufacturing materials of these magnetic devices must also have additional functional properties, such as excellent mechanical properties and excellent corrosion resistance.

[0003] In the method of single pulse electrodeposition of NiFe alloy magnetic coating with patent number CN105780068B, Ni-Fe alloy coating is prepared by single pulse technology, and the coating quality is improved by adjusting the pulse current density, pulse time, intermittent time and other parameters, and the alloy coating with high hardness, low cohesion and fine and tight structure layer is obtained. However, this method has the problems of relatively complex equipment, high cost, many adjustable pulse electrodeposition parameters, and difficult operation.

[0004] The electrochemical deposition three-electrode system is now widely used. In terms of electrode selection, the working electrode and the counter electrode form a circuit, and the reference electrode is introduced as a reference for measuring or applying the working electrode potential. The reference electrode must maintain a constant potential, on an absolute scale, to keep the potential stable. Commonly used reference electrodes include saturated calomel electrode (SCE) in neutral solution, Ag / AgCl electrode in acidic environment, reversible hydrogen electrode (RHE), Hg / HgO electrode in alkaline environment, etc. However, the three-electrode system still has problems such as polarization effect, limited current control, and interference from side reactions.

[0005] Based on the above-mentioned problems existing in electrochemical deposition, a new process method needs to be proposed to reduce the influence of polarization phenomenon and the occurrence of side reactions during the deposition process, so as to obtain a more delicate, tight and uniform coating with better corrosion resistance and magnetic properties, while enhancing the life of the reference electrode. Summary of the invention

[0006] The purpose of the present invention is to provide a method for plating Fe-Co-Ni thin films using double reference electrodes to solve the following problems existing in the prior art: the occurrence of side reactions caused by liquid junction potential affects the rate and limit of the target reaction, which is mainly manifested in the thickness and quality of the coating; when the potential drift exceeds the reaction electromotive force, the reaction kinetics stops, which is electrode instability and greatly affects the continuity of industrial deposition; in addition, excessive potential drift will also reduce the wastewater treatment effect or the coating quality, and affect the mechanical properties, corrosion resistance and magnetic energy of the coating film.

[0007] The method for plating a Fe-Co-Ni thin film using a double reference electrode provided by the present invention comprises the following steps:

[0008] S1, adding choline chloride, levulinic acid and water into a Haring cell, and then adding chlorides of Fe, Co and Ni to obtain an electrodeposition solution;

[0009] S2. Connect the copper sheet and the platinum sheet to the two poles of the power supply respectively, and ground two reference electrodes of the same type respectively, and use an external bridge to keep the potential difference at a constant value;

[0010] S3. Perform an electrodeposition experiment using cyclic voltammetry to obtain a Fe-Co-Ni film on the copper sheet.

[0011] In the method of the present invention, in step S1, the chloride is added in a constant temperature water bath;

[0012] The chloride of Fe is FeCl 2 ; The chloride of Co is CoCl 2 ; The chloride of Ni is NiCl 2 .

[0013] In the method of the present invention, in step S2, the copper sheet and the platinum sheet are both pre-treated as follows before being connected to the power supply:

[0014] Degrease and pickle with degreaser and sulfuric acid, then dry with cold air.

[0015] In the method of the present invention, in step S2, the reference electrode is a calomel electrode, an Ag / AgCl electrode or a Hg / HgO electrode. Generally, the calomel electrode is suitable for iron plating in a ferric chloride system, and the Ag / AgCl electrode is suitable for copper plating with divalent copper ions.

[0016] In the method of the present invention, before step S3, the working potential is first determined: the sum of the reaction potential and the potential difference is the working potential.

[0017] In the method of the present invention, the conditions for the electrodeposition are as follows:

[0018] Reaction potential difference (E 工作电极-E 参比电极 ) is 0.05V~1.1V, the working potential difference (E 工作电极 -E 对电极 ) is 2V~20V;

[0019] The temperature of the electrodeposition is usually 40-70° C. A temperature that is too high will lead to non-electrochemical side reactions, while a temperature that is too low will cause the reaction to start too slowly.

[0020] The Fe-Co-Ni coating prepared by the method of the invention has a flat, uniform, fine and tight structure.

[0021] The chemical corrosion potential of the coating prepared by the method of the present invention is -0.437, and its self-corrosion current density is 7.143×10 -5 A.cm -2 , with better corrosion resistance.

[0022] In the present invention, since the two reference electrodes are in the same environment, the electrode drift is synchronized, the working potential difference can be controlled in a very stable range, and the theoretical instability life is consistent with the inactivation life of the reference electrode (10 6 r~10 7 r), which is much longer than the theoretical instability lifetime of the three-electrode system (10 5 r~10 6 r), so double reference can greatly reduce the cost of reference electrode and the stability of continuous production.

[0023] The present invention utilizes the potential difference between two reference electrodes as the reference potential, which has extremely small fluctuations (below 0.001V), and the working potential difference can be adjusted very accurately, so that the side reactions that may occur in the battery can be accurately reduced, and a stable and reliable reference potential can be provided to ensure the stability of the working environment of the battery, thereby minimizing undesirable reactions in the electrochemical reaction.

[0024] In the present invention, since the reference potential is a potential difference and does not change with the reaction potential, the reaction potential can be appropriately increased within the range allowed by theory. Experiments show that when the reaction potential is increased to about 20V, the deposited product is still relatively specific. In contrast, when the reaction potential of the three electrodes is 9V, the Fe(III) content in the coating increases significantly. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 are SEM images of Fe-Co-Ni coatings under different deposition conditions.

[0026] Figure 2 It is the XRD spectrum of the Fe-Co-Ni coating prepared in the temperature range of 30 to 60°C.

[0027] Figure 3It is the potentiodynamic polarization diagram of Fe-Co-Ni coating in 3.5wt% NaCl solution at different deposition temperatures. DETAILED DESCRIPTION

[0028] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0029] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0030] Embodiment 1,

[0031] Step 1: Add choline chloride (C 5 H 14 ClNO), levulinic acid (C 5 H 8 O 3 ), water, and stirred in a 30°C constant temperature water bath. Then, metal chloride FeCl 2 、NiCl 2 、CoCl 2 An electrodeposition solution is obtained.

[0032] Step 2: Use degreasing agent LP-200 and sulfuric acid to degrease and pickle the copper sheet with a size of 5×5×0.5cm and the platinum sheet with a size of 5×5×0.5cm for pretreatment, then use cold air to dry, connect the treated working electrode (Zn plated part) and counter electrode (standard Pt electrode) to the two poles of the power supply respectively, connect two calomel reference electrodes (one is the standard calomel reference electrode 0.2801V, and the other is the adjusted calomel electrode 0.5602V) to the electroplating equipment, and keep the potential difference at 0.2801V.

[0033] Step 3: Use the chronoamperometry to conduct the electrodeposition experiment, set the lower limit of the deposition potential to -17 to -17.8 V, the upper limit to 1.7 V to 2.3 V, the difference between the double references to 0.2 to 1.9 V, the total charge Q to 0.1 to 1.0 Q, the constant temperature water bath temperature to 30 ° C -70 ° C, the pH of the solution to 4-5, and the deposition time to 3600s-5400s.

[0034] Step 4: After the experiment, a silver-white metal coating was formed on the surface of the Zn-plated working electrode. After the deposition was completed, the deposited product was first washed with deionized water and anhydrous ethanol, then dried with nitrogen, and finally stored in a glove box for subsequent use and testing.

[0035] Table 1 shows the relationship between the potential difference between the reference electrode potential, the double reference electrode potential and the standard electrode potential and their cycle numbers. It can be seen that the single reference electrode potential has a large drift when the cycle number is high, while the double reference electrode, after determining the initial electrodeposition environment and potential difference, has a potential difference with the standard electrode of less than 0.0001 V when the cycle number is high and close to the theoretical cycle limit of the reference electrode.

[0036] Table 1 Relationship between the potential difference between the reference electrode potential, the double reference electrode potential and the standard electrode potential and their cycle times

[0037] Cycle times <![CDATA[10 4 ]]> <![CDATA[10 5 ]]> <![CDATA[10 6 ]]> <![CDATA[10 7 ]]> The potential difference between the reference electrode and the standard reference electrode 0.003 0.022 0.19 0.82 Potential difference between double reference electrode and standard reference electrode ＜0.0001 ＜0.0001 ＜0.0001 0.0001

[0038] Figure 1 The solution pH is 4.5 (left) and 5.5 (right), and the coatings of the single reference electrode (top) and the double reference electrode (bottom) are deposited on the Zn-plated parts at a unified temperature of 50°C and a deposition time of 60s. The SEM image of the Fe-Co-Ni coating obtained shows that the coating using the double reference electrode has better coating flatness.

[0039] The XRD spectra of the Fe-Co-Ni coating prepared in the temperature range of 30 to 60 °C are shown in Figure 2 As shown. Figure 2 It can be observed that the diffraction peaks at 43.5°, 50.8° and 74.5° correspond to the (111), (200) and (220) crystal planes of the Cu substrate, respectively. At a deposition temperature of 60°C, the coating is composed of four crystal structures: FeCo(200), FeCo(220), FeNi(110) and FeCo(110). At this time, the peak intensity of FeCo(200) and FeCo(220) is significantly reduced, indicating a trend of preferential growth, and the crystal structure is transformed from a single body-centered cubic (bcc) to a composite structure containing both body-centered cubic (bcc) and face-centered cubic (fcc).

[0040] Depend on Figure 3 It can be seen that the horizontal axis represents the corrosion potential, the vertical axis represents the corrosion current, and the corrosion tendency of the polarization curve can be reflected by the self-corrosion potential, and the corrosion tendency decreases with the decrease of the corrosion potential, and the smaller the corrosion tendency, the less likely the coating is to be corroded. Therefore, when the temperature is 60°C (other conditions are the same as above), the corrosion resistance is the best.

[0041] The S and Hc detailed lines of the hysteresis loop matrix perpendicular to and parallel to the film surface of the Fe-Co-Ni coating obtained at different temperatures are significantly different, indicating that the coating has magnetic anisotropy. The data parallel and perpendicular to Cu in the hysteresis loop are listed in Table 2. It can be seen that with the increase of temperature, the S∥ of the Fe-Co-Ni coating increases first and then decreases, and S∥ is greater than S⊥, which proves that the Fe-Co-Ni coating exhibits significant parallel magnetic anisotropy and is more likely to be magnetized parallel to the direction of the Fe-Co-Ni coating. The S∥ and S⊥ of the Fe-Co-Ni coating obtained at an electrodeposition temperature of 60°C show the largest difference, and the magnetic anisotropy of the coating is the strongest at this time.

[0042] Table 2 Magnetic data extracted from hysteresis loops of Fe-Co-Ni coatings at different deposition temperatures

[0043]

[0044]

[0045] Table 3 Corrosion electromotive force and self-corrosion current density of single-reference and double-reference Co-based protective films at different deposition temperatures

[0046]

[0047] As shown in Table 3, under the same conditions, the film plated with double reference electrodes has lower corrosion potential and self-corrosion current density than the film plated with single reference electrode. At the same time, the lower the temperature, the lower the corrosion current, and the more corrosion-resistant the coating is.

Claims

1. A method for plating Fe-Co-Ni thin film using double reference electrodes, comprising the following steps: S1, adding choline chloride, levulinic acid and water into a Haring cell, and then adding chlorides of Fe, Co and Ni to obtain an electrodeposition solution; S2. Connect the copper sheet and the platinum sheet to the two poles of the power supply respectively, and ground two reference electrodes of the same type respectively; S3. Perform an electrodeposition experiment using cyclic voltammetry to obtain a Fe-Co-Ni film on the copper sheet.

2. The method according to claim 1, characterized in that: In step S1, the chloride is added in a constant temperature water bath; The chloride of Fe is FeCl2; the chloride of Co is CoCl2; and the chloride of Ni is NiCl2.

3. The method according to claim 1 or 2, characterized in that: In step S2, the copper sheet and the platinum sheet are both pre-treated as follows before being connected to the power supply: Degrease and pickle with degreaser and sulfuric acid, then dry with cold air.

4. The method according to any one of claims 1 to 3, characterized in that: In step S2, the reference electrode is a calomel electrode, an Ag / AgCl electrode or a Hg / HgO electrode.

5. The method according to any one of claims 1 to 4, characterized in that: Before step S3, the working potential is first determined: the sum of the reaction potential and the potential difference is the working potential.

6. The method according to any one of claims 1 to 5, characterized in that: The conditions of the electrodeposition are as follows: The working potential difference is 0.05V~1.1V, and the reaction potential difference is 2V~20V.

7. A Fe-Co-Ni thin film prepared by the method according to any one of claims 1 to 6.

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