Method and device for preparing magnesium-aluminum alloy by means of a double-membrane three-compartment electrolytic cell

Abstract

The application provides a method and device for preparing Mg-Al alloy by using a double-membrane three-chamber electrolytic cell, the method comprises the following steps: in the double-membrane three-chamber electrolytic cell with a cation exchange membrane and an anion exchange membrane as a diaphragm, the double-membrane three-chamber electrolytic cell is sequentially divided into a first anode chamber, a cathode chamber and a second anode chamber, magnesium is used as the anode of the first anode chamber, aluminum is used as the anode of the second anode chamber, and graphite is used as the cathode of the cathode chamber; constant current electrolysis is carried out, magnesium ions generated in the first anode chamber and aluminum ions generated in the second anode chamber migrate into the cathode chamber through the cation exchange membrane and the anion exchange membrane respectively, and Mg-Al alloy is deposited on the cathode of the cathode chamber. In the application, magnesium and aluminum are used as the anodes, graphite is used as the cathode, and co-deposition is realized on the cathode through the ion exchange membrane, so that a Mg-Al alloy coating with good performance and use value is formed. Compared with the prior art, the application has the advantages of no pollution, low energy consumption, high current efficiency and good application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of alloy materials, in particular to a method and device for preparing Mg-Al alloy by using a double-membrane three-chamber electrolytic cell. BACKGROUND

[0002] Mg-Al alloy has excellent corrosion resistance, decoration, oxidation resistance and good mechanical properties, and is an ideal component protection layer. Due to its light weight, it has good development prospects in the aviation industry, and due to its excellent corrosion resistance, it also plays a very important role in the marine transportation industry and the submarine industry. Therefore, developing the preparation technology of Mg-Al alloy has important theoretical significance and practical application value.

[0003] In order to make good use of Mg-Al alloy, it is necessary to prepare pure alloy with ultra-fine structure. Electrodeposition is one of the effective methods for preparing high-purity ultra-fine structure alloy, which has low cost and simple process control, and the particle size produced is uniform. However, since the standard electrode potential of aluminum and magnesium is more negative than that of hydrogen at room temperature, hydrogen will be precipitated during electrodeposition in aqueous solution, which will seriously interfere with the deposition of Mg-Al alloy. Therefore, the electrodeposition of Mg-Al alloy can only be carried out in a non-aqueous electrolyte system. In the molten salt system and organic solvent system for electrodeposition of aluminum alloy, the organic solvent system is the earliest and most widely used. For the electrodeposition of Mg-Al alloy, an organic solvent system mainly containing aluminum chloride and magnesium chloride is generally used. This system realizes the preparation of Mg-Al alloy at room temperature, which is beneficial to energy saving and consumption reduction. However, anhydrous magnesium chloride and aluminum chloride need to be prepared in the laboratory or purchased at a high price. The former has a complex process, and the latter has a high cost. In addition, due to the presence of magnesium chloride and aluminum chloride, the viscosity of the system is large, the conductivity of the electrolyte is poor at room temperature, and the electrochemical window is narrow, which affects its further large-scale application and development. SUMMARY

[0004] Based on the technical problems existing in the background art, the present application proposes a method and device for preparing Mg-Al alloy by using a double-membrane three-chamber electrolytic cell. In the method and device, magnesium and aluminum are used as anodes at room temperature, and graphite is used as a cathode. By electrolysis, magnesium ions and aluminum ions with a certain concentration are obtained, so as to replace magnesium chloride and aluminum chloride. Then, through an ion exchange membrane, co-deposition is realized on the cathode to form a Mg-Al alloy coating with good performance and use value. Compared with the prior art, the method and device of the present application are pollution-free, have low energy consumption, high current efficiency, and have good application prospect.

[0005] The application provides a method for preparing Mg-Al alloy by using a double-membrane three-chamber electrolytic cell.

[0006] Preferably, the electrolyte of the first anode chamber is an isopropyl alcohol solution containing choline chloride;

[0007] Preferably, the concentration of the choline chloride is 0.1-0.5 mol / L.

[0008] Preferably, the electrochemical reaction in the first anode chamber is:

[0009] Mg-2e→Mg 2+ .

[0010] Preferably, the electrolyte of the second anode chamber is an isopropyl alcohol solution containing 1-butyl-2,3-dimethylimidazole chloride;

[0011] Preferably, the concentration of the 1-butyl-2,3-dimethylimidazole chloride is 0.2-0.8 mol / L.

[0012] Preferably, the electrochemical reaction in the second anode chamber is:

[0013] Al-3e→Al 3+ +4Cl - →AlCl4 - .

[0014] Preferably, the electrolyte of the cathode chamber is an isopropyl alcohol solution containing 1-butyl-2,3-dimethylimidazole chloride, choline chloride, ethylenediaminetetraacetic acid, potassium chloride and nicotinamide;

[0015] Preferably, the concentration of the 1-butyl-2,3-dimethylimidazole chloride is 0.2-0.8 mol / L, the concentration of the choline chloride is 0.1-0.5 mol / L, the concentration of the ethylenediaminetetraacetic acid is 0.05-0.3 mol / L, the concentration of the potassium chloride is 0.05-0.3 mol / L, and the concentration of the nicotinamide is 0.05-0.2 mol / L.

[0016] Preferably, the electrochemical reaction in the cathode chamber is:

[0017] Mg 2+ +EDTA→EDTA-Mg 2++2e→Mg+EDTA

[0018] AlCl4 - +3e→Al+4Cl - .

[0019] Preferably, the current density of the constant current electrolysis is 0.5-2mA / dm 2 .

[0020] Preferably, the cation exchange membrane is a Nafion cation exchange membrane, and the anion exchange membrane is a Piperion anion exchange membrane.

[0021] The application further provides a device for preparing Mg-Al alloy by using a double-membrane three-chamber electrolytic cell, comprising: a double-membrane three-chamber electrolytic cell with a cation exchange membrane and an anion exchange membrane as a diaphragm, which is sequentially divided into a first anode chamber, a cathode chamber and a second anode chamber.

[0022] The first anode chamber contains a first anode and a first anode electrolyte, the second anode chamber contains a second anode and a second anode electrolyte, and the cathode chamber contains a cathode and a cathode electrolyte, and the first anode, the second anode and the cathode are respectively connected to the positive and negative poles of a direct current power supply.

[0023] The first anode is magnesium, the first anode electrolyte is an isopropyl alcohol solution containing choline chloride; the second anode is aluminum, the second anode electrolyte is an isopropyl alcohol solution containing 1-butyl-2, 3-dimethyl imidazole chloride; and the cathode is graphite, and the cathode electrolyte is an isopropyl alcohol solution containing 1-butyl-2, 3-dimethyl imidazole chloride, choline chloride, ethylenediamine tetraacetic acid, potassium chloride and nicotinamide.

[0024] In the double-membrane three-chamber electrolytic cell with a cation exchange membrane and an anion exchange membrane as a diaphragm, magnesium is used as the anode of the first anode chamber, aluminum is used as the anode of the second anode chamber, and graphite is used as the cathode of the cathode chamber, and when constant current electrolysis is carried out, the first anode chamber electrochemically reacts to produce Mg 2+ , the second anode chamber electrochemically reacts to produce AlCl4 - , Mg 2+ and AlCl4 - respectively migrate to the cathode chamber through the cation exchange membrane and the anion exchange membrane, and a Mg-Al alloy coating is formed on the graphite cathode of the cathode chamber.

[0025] Compared with the prior art, the application has the following advantages:

[0026] (1) The Mg-Al alloy prepared by the method has small grain size, good surface density, high alloy purity, and good physical and mechanical properties.

[0027] (2) The method has the advantages of safe operation, good electrolyte dispersibility, high current efficiency, reasonable price, and small energy consumption. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 A device structure diagram for preparing Mg-Al alloy by the double-membrane three-chamber electrolytic cell of the present application;

[0029] Figure 2 A surface morphology diagram of the Mg-Al alloy prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0030] In the following, the technical solutions of the present application will be described in detail through specific examples, but it should be made clear that these examples are used for illustration, but not to be interpreted as limiting the scope of the present application.

[0031] Example 1

[0032] Reference Figure 1 The present example proposes a method for preparing Mg-Al alloy by a double-membrane three-chamber electrolytic cell. In a closed double-membrane three-chamber electrolytic cell, Nafion cation exchange membrane and Piperion anion exchange membrane are used as the separator to divide the electrolytic cell into a first anode chamber, a cathode chamber and a second anode chamber in sequence. The first anode chamber contains a first anode and a first anode electrolyte, the second anode chamber contains a second anode and a second anode electrolyte, and the cathode chamber contains a cathode and a cathode electrolyte. The first anode, the second anode and the cathode are respectively connected to the positive and negative electrodes of a direct current power supply.

[0033] The first anode is a magnesium anode with a size of 4 cm x 6 cm, and the first anode electrolyte is an isopropyl alcohol solution containing 0.4 mol / L choline chloride (ChCl). The second anode is an aluminum anode with the same size of 4 cm x 6 cm, and the second anode electrolyte is an isopropyl alcohol solution containing 0.6 mol / L 1-butyl-2,3-dimethylimidazole chloride (BDMIMCl). The cathode is a graphite cathode with a size of 6 cm x 8 cm, and the cathode electrolyte is an isopropyl alcohol solution containing 0.5 mol / L 1-butyl-2,3-dimethylimidazole chloride (BDMIMCl), 0.3 mol / L choline chloride (ChCl), 0.1 mol / L ethylenediaminetetraacetic acid (EDTA), 0.1 mol / L potassium chloride (KCl) and 0.1 mol / L nicotinamide.

[0034] In the working process, the first anode, the second anode and the cathode are respectively placed in the corresponding first anode chamber, the second anode chamber and the cathode chamber in the inert gas environment of Ar, the distance between the anode and the cathode is kept at 0.4 cm, the first anode electrolyte, the second anode electrolyte and the cathode electrolyte are respectively injected into the corresponding first anode chamber, the second anode chamber and the cathode chamber, the electrolyte is stirred at a speed of 800 r / min, the temperature of the electrolyte is kept at 30℃, the constant current electrolysis is carried out at a current density of 1 A / dm 2 After the completion, the cathode is taken out, the deposits on the cathode are washed with ethanol and deionized water in turn, and the Mg-Al alloy is obtained after being blown dry.

[0035] Example 2

[0036] With reference Figure 1 , this embodiment also proposes a method for preparing Mg-Al alloy by using a double-membrane three-chamber electrolytic cell, which is the same as that in Example 1, except that the first anode electrolyte is an isopropyl alcohol solution containing 0.5 mol / L choline chloride (ChCl), and the second anode electrolyte is an isopropyl alcohol solution containing 0.7 mol / L 1-butyl-2,3-dimethylimidazole chloride (BDMIMCl).

[0037] In the working process, the electrolyte is stirred at a speed of 1000 r / min, the temperature of the electrolyte is kept at 35℃, the constant current electrolysis is carried out at a current density of 1.2 A / dm 2 After the completion, the cathode is taken out, and the Mg-Al alloy is obtained.

[0038] The above merely describes the preferred embodiments of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can make equivalent substitutions or changes to the technical solutions and the inventive concept of the present application within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.

Claims

1. A method for preparing Mg-Al alloys using a double-membrane three-chamber electrolytic cell, characterized in that, include: In a double-membrane three-chamber electrolyzer with cation exchange membrane and anion exchange membrane as diaphragms, the double-membrane three-chamber electrolyzer is sequentially divided into a first anode chamber, a cathode chamber, and a second anode chamber. Magnesium is used as the anode of the first anode chamber, aluminum is used as the anode of the second anode chamber, and graphite is used as the cathode of the cathode chamber. Constant current electrolysis is performed so that magnesium ions generated in the first anode chamber and aluminum ions generated in the second anode chamber migrate to the cathode chamber through the cation exchange membrane and the anion exchange membrane, respectively, and deposit on the cathode of the cathode chamber to form a Mg-Al alloy. The electrolyte in the first anode chamber is an isopropanol solution containing choline chloride; the electrolyte in the second anode chamber is an isopropanol solution containing 1-butyl-2,3-dimethylimidazole chloride; and the electrolyte in the cathode chamber is an isopropanol solution containing 1-butyl-2,3-dimethylimidazole chloride, choline chloride, ethylenediaminetetraacetic acid, potassium chloride, and nicotinamide.

2. The method for preparing Mg-Al alloys using a double-membrane three-chamber electrolytic cell according to claim 1, characterized in that, The concentration of choline chloride in the electrolyte of the first anode chamber is 0.1-0.5 mol / L.

3. The method for preparing Mg-Al alloys using a double-membrane three-chamber electrolytic cell according to claim 2, characterized in that, The electrochemical reaction in the first anode chamber is as follows: Mg-2e→Mg 2+ 。 4. The method for preparing Mg-Al alloys using a double-membrane three-chamber electrolytic cell according to any one of claims 1-3, characterized in that, In the electrolyte of the second anode chamber, the concentration of 1-butyl-2,3-dimethylimidazole chloride is 0.2-0.8 mol / L.

5. The method for preparing Mg-Al alloys using a double-membrane three-chamber electrolytic cell according to claim 4, characterized in that, The electrochemical reaction in the second anode chamber is as follows: Al-3e→Al 3+ +4Cl - →AlCl4 - 。 6. The method for preparing Mg-Al alloys using a double-membrane three-chamber electrolytic cell according to any one of claims 1-3, characterized in that, In the electrolyte of the cathode chamber, the concentrations of 1-butyl-2,3-dimethylimidazole chloride are 0.2-0.8 mol / L, choline chloride is 0.1-0.5 mol / L, ethylenediaminetetraacetic acid is 0.05-0.3 mol / L, potassium chloride is 0.05-0.3 mol / L, and nicotinamide is 0.05-0.2 mol / L.

7. The method for preparing Mg-Al alloys using a double-membrane three-chamber electrolytic cell according to claim 6, characterized in that, The electrochemical reaction inside the cathode chamber is as follows: Mg 2+ +EDTA→EDTA-Mg 2+ +2e→Mg+EDTA AlCl4 - +3e→Al+4Cl - 。 8. The method for preparing Mg-Al alloys using a double-membrane three-chamber electrolytic cell according to any one of claims 1-3, characterized in that, The current density of the constant current electrolysis is 0.5-2 mA / dm³. 2 .

9. The method for preparing Mg-Al alloys using a double-membrane three-chamber electrolytic cell according to any one of claims 1-3, characterized in that, The cation exchange membrane is a Nafion cation exchange membrane, and the anion exchange membrane is a Piperion anion exchange membrane.

10. An apparatus for preparing Mg-Al alloys using a double-membrane three-chamber electrolytic cell, characterized in that, include: A double-membrane three-chamber electrolyzer with cation exchange membrane and anion exchange membrane as diaphragms is sequentially divided into a first anode chamber, a cathode chamber, and a second anode chamber. The first anode chamber contains a first anode and a first anode electrolyte, the second anode chamber contains a second anode and a second anode electrolyte, and the cathode chamber contains a cathode and a cathode electrolyte. The first anode, the second anode, and the cathode are respectively connected to the positive and negative terminals of a DC power supply. The first anode is magnesium, and the first anode electrolyte is an isopropanol solution containing choline chloride; the second anode is aluminum, and the second anode electrolyte is an isopropanol solution containing 1-butyl-2,3-dimethylimidazole chloride; the cathode is graphite, and the cathode electrolyte is an isopropanol solution containing 1-butyl-2,3-dimethylimidazole chloride, choline chloride, ethylenediaminetetraacetic acid, potassium chloride, and nicotinamide.

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