Spinel type ceramic coated HEA core-shell powder material as well as preparation method and application thereof

Abstract

The invention provides a spinel type ceramic (at) HEA core-shell powder material and a preparation method and application thereof, and the preparation method comprises the following steps: (1) cleaning high-entropy alloy powder to obtain a high-entropy alloy matrix; (2) preparing metal salt into a solution according to a stoichiometric ratio, dropwise adding a complexing agent and a precipitating agent into the solution, and carrying out a co-precipitation reaction to obtain ceramic coating phase slurry; (3) coating the ceramic coating phase in the slurry on the surface of the high-entropy alloy matrix through a dip-coating method or a spraying method to form a high-entropy alloy precursor; and (4) sequentially grinding and sintering the high-entropy alloy precursor to obtain the spinel type ceramic (at) HEA core-shell powder material. When the spinel type ceramic coated HEA core-shell powder material prepared by the method is applied to an aluminum electrolysis inert anode material, the corrosion resistance and the mechanical strength can be remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of electrochemical composite materials, and in particular to a spinel-type ceramic@HEA core-shell powder material and a preparation method and application thereof. Background Art

[0002] In traditional aluminum electrolysis, carbon anodes are the primary anode material used in the cryolite-alumina molten salt electrolysis process. During the electrolysis process, carbon anodes corrode and consume, requiring frequent and extensive replacement, resulting in significant labor. The consumption of carbon anodes also produces large amounts of CO2, along with toxic gases such as CF4, C2F6, and HF, which contribute to severe air pollution. Inert anodes, on the other hand, consume no or minimal oxygen during the electrolysis process, saving the electrolytic cell energy by up to 35%. Furthermore, the oxygen produced as a byproduct can be utilized in other research areas. In recent years, research on the selection of inert anode materials has focused on metals, oxide ceramics, cermets, and other composite anode materials, with the goal of improving their performance through the addition of intermediate layers and coating modification techniques.

[0003] High-entropy alloys (HEAs), as a new type of alloy material, have excellent electrical conductivity due to their special high configurational entropy and functional properties. More and more scholars are introducing them into the field of electrochemical research. However, during the aluminum electrolysis process, oxygen is continuously generated at the inert anode. HEA forms an oxide film on its surface under oxygen-rich conditions, which may make its corrosion resistance difficult to meet the requirements of an inert anode. Research on ceramic materials as inert anodes for aluminum electrolysis is still limited to their use as metal ceramics in electrolysis experiments. The product purity can reach over 98%, and the maximum oxygen production reaches 99%. However, ceramics have poor electrical conductivity. Existing HEA or ceramic coating technologies (such as CVD and PVD) rely on complex equipment, are costly, and difficult to achieve uniform nanoscale coating. They cannot provide long-term corrosion protection in harsh electrolysis environments. Mechanical mixing methods are prone to weak interface bonding and component segregation.

[0004] CN114523101A discloses a "core-shell material of high-entropy oxide or high-entropy oxide, graphene-coated high-entropy alloy and a method for preparing a bimodal structure composite material". A hydrothermal reaction and roasting process are used to prepare a core-shell material of a high-entropy ceramic oxide or a graphene-coated high-entropy alloy. The ceramic oxide or graphene particles are uniformly embedded in the high-entropy alloy powder through high-speed and low-temperature ball milling to form a mixed metal-based composite material with a bimodal structure. The effective combination of high-entropy ceramic oxide and graphene with the high-entropy alloy is achieved, and the mechanical properties of the metal-based composite material are improved, especially in terms of strength and toughness. However, there has not been much research on the corrosion resistance.

[0005] Therefore, how to improve the method of coating HEA with ceramic materials to form a core-shell structure in order to improve the corrosion resistance of the material has become the current main research focus. Summary of the Invention

[0006] In view of this, the present invention aims to provide a spinel-type ceramic@HEA core-shell powder material and a preparation method thereof. The spinel-type ceramic@HEA core-shell powder material obtained by the preparation method of the present invention can significantly improve corrosion resistance and mechanical strength when used as an inert anode material for aluminum electrolysis.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0008] The present invention provides a method for preparing a spinel ceramic@HEA core-shell powder material, comprising the following steps:

[0009] (1) washing the high entropy alloy powder to obtain a high entropy alloy matrix;

[0010] (2) preparing a solution of metal salts according to a stoichiometric ratio, and adding a complexing agent and a precipitant dropwise into the solution to perform a co-precipitation reaction to obtain a ceramic coating phase slurry;

[0011] (3) coating the ceramic coating phase in the slurry on the surface of the high entropy alloy substrate by an immersion pulling method or a spraying method to form a high entropy alloy precursor;

[0012] (4) The high entropy alloy precursor is ground and sintered in sequence to obtain a spinel ceramic@high entropy alloy core-shell powder material.

[0013] Preferably, the specific steps of step (2) are as follows:

[0014] 1) Weigh the metal salt according to the stoichiometric ratio, dissolve it in deionized water at 80-100°C, and stir it magnetically until it is completely dissolved to prepare a solution with an ion concentration of 0.1-10 mol / L;

[0015] 2) The precipitant is prepared at a molar ratio of 1.5:1 to the metal ion; the complexing agent is prepared at a molar ratio of 1:0.1 to 3 to the metal ion, the water bath temperature is controlled at 20 to 30° C., 0.5 to 2 wt % of a dispersant is added, and the precipitant and complexing agent are dripped into the metal salt solution at a rate of 1 to 2 mL / min to perform a co-precipitation reaction to obtain a ceramic coating phase slurry.

[0016] Preferably, the complexing agent includes one or more of ethylenediaminetetraacetic acid, sodium pyrophosphate, ammonia water, ammonium chloride, ammonium sulfate, ammonium nitrate, ammonium citrate, ethylenediamine, acetic acid, ammonium acetate, sodium fluoride, tartaric acid, maleic acid, succinic acid, citric acid and malonic acid.

[0017] Preferably, the metal salt includes one or more of cobalt salt, nickel salt, iron salt, manganese salt, aluminum salt, copper salt, magnesium salt, and zinc salt;

[0018] The cobalt salt comprises one or more of cobalt carbonate, cobalt chloride, cobalt nitrate, cobalt sulfate, and cobalt acetate;

[0019] The nickel salt includes one or more of nickel nitrate, nickel chloride, and nickel sulfate; the iron salt includes one or more of iron nitrate, iron chloride, and iron sulfate;

[0020] The manganese salt includes one or more of manganese nitrate, manganese chloride, and manganese sulfate;

[0021] The aluminum salt includes one or more of aluminum nitrate, aluminum chloride, and aluminum sulfate;

[0022] The copper salt includes one or more of copper nitrate, copper chloride, and copper sulfate;

[0023] The magnesium salt includes one or more of magnesium chloride and magnesium sulfate;

[0024] The zinc salt includes one or more of zinc chloride and zinc sulfate.

[0025] Preferably, the pH value of the coprecipitation reaction is 8-10.

[0026] Preferably, the precipitant includes one or more of ammonia water, urea, NH4HCO3, NaOH, KOH, Na2CO3, and Cu(OH)2.

[0027] Preferably, the dispersant includes one or more of polyvinyl alcohol, polyvinyl pyrrolidone and sodium lauryl sulfate.

[0028] Preferably, in step (4), the sintering is carried out in an oxidizing atmosphere, the sintering heating rate is 2-20° C. / min, the sintering temperature is 500-900° C., and the sintering time is 3-30 h.

[0029] The present invention also provides a spinel ceramic@HEA core-shell powder material prepared by the above method, wherein the shell thickness of the core-shell structure is 50 to 500 nm, and the molar ratio of the core layer to the shell layer is 1:0.8 to 1:1.2.

[0030] The present invention also provides an inert anode material for aluminum electrolysis, which is prepared by using the spinel ceramic@HEA core-shell powder material prepared by the above method.

[0031] Preferably, the method for preparing an inert anode material for aluminum electrolysis using the spinel ceramic @HEA core-shell powder material comprises the following steps: mixing the spinel ceramic @HEA powder material with a binder, pressing and molding, sintering, and heat treating to obtain the inert anode material for aluminum electrolysis.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The present invention provides a method for preparing a spinel-type ceramic@HEA core-shell powder material. The method mainly adopts a chemical coprecipitation method to disperse high entropy alloy (HEA) powder in deionized water to form uniformly distributed spherical or quasi-spherical particles in the deionized water. When a metal salt solution is slowly dripped into it, the metal ions undergo a chemical coprecipitation reaction under the action of a precipitant, forming a layer of spinel-type oxide on the surface of the particles, thereby obtaining a core-shell powder material with a high entropy alloy (HEA) core layer and a ceramic coating phase as a shell layer. The core-shell powder material is used to prepare an inert anode material for aluminum electrolysis, and can give full play to the excellent mechanical properties of the high entropy alloy core-shell structure and the corrosion resistance of the spinel ceramic.

[0034] The spinel ceramic material of the shell layer of the core-shell powder material of the present invention forms a dense passivation layer, which prevents the penetration of the corrosive medium. In addition, the metal cations in the spinel form a stable oxide / hydroxide passivation film in the electrolyte, further slowing down the oxidative dissolution of the alloy. The HEA substrate of the core layer of the present invention forms a passivation film with complex composition due to the synergistic effect of multiple principal elements, which improves the density and self-repairing ability. In this spinel ceramic @HEA core-shell powder material, a coherent or semi-coherent interface is formed between the spinel ceramic and the HEA matrix (such as the bonding of oxygen atoms in the spinel to metal atoms on the surface of the HEA), which reduces interface defects and avoids the formation of corrosion microbatteries. Through the composite design of spinel ceramics and high entropy alloys, the "passivation-conductivity" dual-functional synergistic effect is achieved, providing a new idea for the development of high-performance inert anode materials for aluminum electrolysis.

[0035] The experimental results show that the core-shell powder material prepared by the present invention is used as an inert anode material for aluminum electrolysis. The corrosion resistance test shows that the corrosion rate is <5mg / cm 2 ·h. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a scanning electron microscope spectrum of the inert anode material of Example 1 of the present disclosure. DETAILED DESCRIPTION

[0037] The present invention provides a method for preparing a spinel ceramic@HEA core-shell powder material, comprising the following steps:

[0038] (1) washing the high entropy alloy powder to obtain a high entropy alloy matrix;

[0039] (2) preparing a solution of metal salts according to a stoichiometric ratio, and adding a complexing agent and a precipitant dropwise into the solution to perform a co-precipitation reaction to obtain a ceramic coating phase slurry;

[0040] (3) coating the ceramic coating phase in the slurry on the surface of the high entropy alloy substrate by an immersion pulling method or a spraying method to form a high entropy alloy precursor;

[0041] (4) The high entropy alloy precursor is ground and sintered in sequence to obtain the spinel ceramic@HEA core-shell powder material.

[0042] In the present invention, unless otherwise specified, the raw materials used are commercially available products in the art.

[0043] The present invention cleans the high entropy alloy powder to obtain a high entropy alloy matrix;

[0044] In the present invention, the metal elements of the high entropy alloy preferably include one or more of nickel, iron, cobalt, copper, aluminum, magnesium, zinc, manganese, titanium, chromium, tantalum, niobium, tungsten, vanadium, molybdenum, hafnium and zirconium. In the present invention, the high entropy alloy is preferably composed of five or more metal elements, preferably five or more of nickel, iron, cobalt, copper, aluminum, zinc, manganese, titanium, chromium, tantalum, niobium, tungsten, vanadium, molybdenum, hafnium and zirconium; in a specific embodiment of the present invention, Co 0.1 Cr 0.1 Fe 0.1 Mn 0.1 Ni 0.1 High entropy alloy.

[0045] In the present invention, the size of the high entropy alloy powder is preferably 50 nm to 1 μm, more preferably 100 to 500 nm.

[0046] In the present invention, the cleaning is preferably ultrasonic cleaning or plasma cleaning; in the present invention, the ultrasonic cleaning frequency is preferably 20kHz to 40kHz, the ultrasonic cleaning temperature is preferably 40 to 60°C, and the ultrasonic cleaning time is preferably 5 to 10 minutes. In the present invention, the plasma cleaning preferably uses Ar plasma treatment to remove surface organic matter, followed by etching in HF solution; in the present invention, the plasma cleaning power is preferably 40 to 60W, the plasma cleaning time is preferably 5 to 10 minutes, and the etching time is preferably 10 to 20 seconds. In the present invention, the high entropy alloy is preferably polished before cleaning, and the polishing uses SiC sandpaper, and the surface Ra after polishing is <0.1um.

[0047] In the present invention, metal salts are prepared into a solution according to a stoichiometric ratio, and a complexing agent and a precipitant are added dropwise into the solution to perform a co-precipitation reaction to obtain a ceramic coating phase slurry.

[0048] In the present invention, the concentration of the solution is preferably 0.1-10 mol / L; the solution preparation method is preferably: weighing the metal salt according to the stoichiometric ratio, dissolving it in 80-100°C deionized water, and magnetically stirring until it is completely dissolved to prepare a solution.

[0049] In the present invention, the coprecipitation reaction is preferably: the precipitant is configured at a concentration of 1.5:1 in a molar ratio to the metal ion; the complexing agent is configured at a concentration of 1:0.1 to 3 in a molar ratio to the metal ion, the water bath temperature is controlled at 20 to 30°C, 0.5 to 2 wt% of a dispersant is added, and the precipitant and complexing agent are dripped into the metal salt solution at a rate of 1 to 2 mL / min to carry out a chemical coprecipitation reaction to obtain a ceramic coating phase slurry.

[0050] In the present invention, the pH value condition of the coprecipitation reaction is 8-10.

[0051] In the present invention, the metal salt metal elements preferably include one or more of nickel, iron, cobalt, copper, aluminum, magnesium, zinc, manganese, titanium, chromium, tantalum, niobium, tungsten, vanadium, molybdenum, hafnium and zirconium.

[0052] In the present invention, the metal salt preferably includes one or more of cobalt salts, nickel salts, iron salts, manganese salts, aluminum salts, copper salts, magnesium salts, and zinc salts; the cobalt salt preferably includes one or more of cobalt carbonate, cobalt chloride, cobalt nitrate, cobalt sulfate, and cobalt acetate; the nickel salt preferably includes one or more of nickel nitrate, nickel chloride, and nickel sulfate; the iron salt includes one or more of iron nitrate, iron chloride, and iron sulfate; the manganese salt preferably includes one or more of manganese nitrate, manganese chloride, and manganese sulfate; the aluminum salt preferably includes one or more of aluminum nitrate, aluminum chloride, and aluminum sulfate; the copper salt preferably includes one or more of copper nitrate, copper chloride, and copper sulfate; the magnesium salt preferably includes one or more of magnesium chloride and magnesium sulfate; and the zinc salt includes one or more of zinc chloride and zinc sulfate.

[0053] In the present invention, the complexing agent preferably includes one or more of ethylenediaminetetraacetic acid, sodium pyrophosphate, ammonia water, ammonium chloride, ammonium sulfate, ammonium nitrate, ammonium citrate, ethylenediamine, acetic acid, ammonium acetate, sodium fluoride, tartaric acid, maleic acid, succinic acid, citric acid and malonic acid.

[0054] In the present invention, the precipitant preferably includes one or more of ammonia water, urea, NH4HCO3, NaOH, KOH, Na2CO3, and Cu(OH)2.

[0055] In the present invention, the dispersant preferably includes one or more of polyvinyl alcohol, polyvinyl pyrrolidone, and sodium lauryl sulfate. During the grinding stage, the dispersant isolates the particles through steric hindrance or electrostatic repulsion, ensuring monodispersity. During the sintering stage, the nanopores left by the dispersant decomposition can relieve sintering stress, reduce cracks, and improve the thermal shock resistance of the inert anode material.

[0056] The present invention coats the ceramic coating phase in the slurry on the surface of the high entropy alloy substrate by an immersion pulling method or a spraying method to obtain a high entropy alloy precursor;

[0057] In the present invention, the immersion pulling method is preferably as follows: immersing the high entropy alloy substrate in the slurry, pulling at a speed of 0.1 to 50 mm / s, and coating the surface of the high entropy alloy substrate with a ceramic coating phase to obtain a high entropy alloy precursor;

[0058] In the present invention, the spraying method is preferably to add a binder (with a concentration of 0.5-5%) to the slurry, and atomize and spray it on the surface of the high entropy alloy substrate to obtain the high entropy alloy precursor.

[0059] In the present invention, the binder includes one or more of polyvinyl alcohol, alumina, nickel ferrite, polyvinyl chloride, phenolic resin, polyethylene oxide, acrylic resin, and hydroxypropyl cellulose.

[0060] In the present invention, the solid-liquid ratio in the precursor preparation process is preferably 1:10 to 1:50. After obtaining the high entropy alloy precursor, the present invention preferably performs a drying treatment, and the drying conditions are preferably vacuum drying at 60 to 80° C. for 12 hours.

[0061] After obtaining the high entropy alloy precursor, the present invention grinds and sinters the precursor in sequence to obtain a spinel ceramic@high entropy alloy core-shell powder material.

[0062] In the present invention, the sintering is preferably performed in an oxidizing atmosphere, the sintering heating rate is preferably 2 to 20°C / min, the sintering temperature is preferably 500 to 900°C, and the sintering time is preferably 3 to 30 hours. The present invention does not specifically limit the grinding process, and conventional grinding methods can be used to form a powder structure.

[0063] The present invention also provides a spinel ceramic @HEA core-shell powder material prepared by the above method, characterized in that the core-shell powder material has a core-shell structure, the core layer is a high entropy alloy matrix, the shell layer is a ceramic coating phase, the shell layer thickness of the core-shell structure is 50 to 500 nm, and the molar ratio of the core layer to the shell layer is 1:0.8 to 1:1.2.

[0064] In the present invention, the high entropy alloy material is composed of five or more metal elements, preferably five or more of nickel, iron, cobalt, copper, aluminum, zinc, manganese, titanium, chromium, tantalum, niobium, tungsten, vanadium, molybdenum, hafnium and zirconium; the ceramic coating phase is a spinel structure, including but not limited to one or a mixture of NiFe2O4, CoFe2O4, NiAl2O4, MgAl2O4, FeAl2O4, ZnFe2O4, MnFe2O4, CuFe2O4, MgFe2O4, ZnAl2O4, FeCr2O4, MgCr2O4, ZnCrO4, Al2(CrO4)3, NiCrO4, CuCrO4, CoCrO4, and MnCrO4.

[0065] The present invention also provides an inert anode material for aluminum electrolysis, comprising a spinel ceramic @HEA powder material and a binder;

[0066] In the present invention, the aluminum electrolysis inert anode material is prepared using the above-mentioned spinel ceramic @HEA core-shell powder material, including: mixing the spinel ceramic @HEA powder with a binder, pressing and molding, and then sintering and heat treating.

[0067] In the present invention, the mass ratio of the spinel ceramic @HEA powder to the binder is 1 to 20:1. In the present invention, the sintering temperature is preferably 1000 to 1500°C, more preferably 1200°C; the sintering time is preferably 2 to 6 hours, more preferably 3 hours; the heating rate before sintering is preferably 5°C / min to 10°C / min; the heat treatment is preferably furnace cooling or rapid cooling, and the heat treatment time is preferably 1 to 4 hours; the present invention uses heat treatment to eliminate residual stress that may be generated during the sintering process and further improve the mechanical properties of the material.

[0068] In the present invention, the binder includes one or more of polyvinyl alcohol, alumina, nickel ferrite, polyvinyl chloride, phenolic resin, polyethylene oxide, acrylic resin, and hydroxypropyl cellulose.

[0069] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0070] Example 1

[0071] 1. NiFe2O4@Co 0.1 Cr 0.1 Fe 0.1 Mn0.1 Ni 0.1 Preparation of HEA powder;

[0072] 1.1 Preparation of Co 0.1 Cr 0.1 Fe 0.1 Mn 0.1 Ni 0.1 HEA substrate: Co at a molar ratio of Co:Cr:Fe:Mn:Ni=0.1:0.1:0.1:0.1:0.1 0.1 Cr 0.1 Fe 0.1 Mn 0.1 Ni 0.1 The high entropy alloy was polished step by step with SiC sandpaper to Ra < 0.1 μm, treated with Ar plasma (50 W, 5 min) to remove organic matter, and etched with 5% HF solution for a short time (10-20 seconds) to obtain a HEA substrate with uniform composition and ultra-smooth surface;

[0073] 1.2 NiFe2O4@Co 0.1 Cr 0.1 Fe 0.1 Mn 0.1 Ni 0.1 Preparation of HEA powder precursor system:

[0074] Iron salt (ferric nitrate) and nickel salt (nickel nitrate) were weighed and dissolved in deionized water in a stoichiometric ratio of 2:1. The solution was stirred in a magnetic stirrer for 10 minutes until a clear solution was obtained. Acetylacetone was added as a complexing agent and PVP as a thickener to control the sol viscosity to 30 cP. The metal salt was dissolved in the mixed solvent and magnetically stirred (40 ° C, 2 h) until completely dissolved. Ammonia was added dropwise to adjust the pH to 3-4. After aging for 24 h, the HEA substrate was vertically immersed in the sol. The immersion time was 10-30 s and the pulling speed was 1-5 mm / s. An electric pulling machine was used to maintain a constant speed. The solution was allowed to stand at room temperature for 10 minutes and dried at 80 ° C for 30 minutes. After each layer was coated, it was lightly sintered (300 ° C, 10 min, Ar atmosphere) before the next layer was coated to avoid re-dissolution of the sol to obtain uniform NiFe2O4@Co 0.1 Cr 0.1 Fe 0.1 Mn 0.1 Ni 0.1 HEA powder precursor system;

[0075] 1.3 NiFe2O4@Co 0.1 Cr 0.1 Fe 0.1 Mn 0.1 Ni 0.1 Preparation of HEA powder:

[0076] The obtained NiFe2O4@HEA precursor system was centrifuged, washed twice with deionized water and anhydrous ethanol, and then the precipitate was transferred to a vacuum drying oven and vacuum dried at 70°C for 24 hours. The dried sample was transferred to a tube furnace and calcined in a mixed reducing atmosphere of hydrogen and nitrogen at a calcination temperature of 700°C, a heating rate of 3°C / min, and a calcination time of 3 hours. After calcination, it was cooled to room temperature with the furnace. 0.1 Cr 0.1 Fe 0.1 Mn 0.1 Ni 0.1 HEA powder and protective medium tert-butyl alcohol (TBA) were mechanically ball milled in a tungsten carbide tank at 240 rpm with a ball to composite material mass ratio of 20:1 for 4 h. The powder material was then dried in a freeze dryer for 24 h to fully remove TBA and sieved with 200 mesh to obtain NiFe2O4@Co 0.1 Cr 0.1 Fe 0.1 Mn 0.1 Ni 0.1 HEA core-shell powder material.

[0077] 2. Preparation and performance testing of inert anode materials for aluminum electrolysis;

[0078] 2.1、Preparation of inert anode materials for aluminum electrolysis: NiFe2O4@Co 0.1 Cr 0.1 Fe 0.1 Mn 0.1 Ni 0.1 HEA powder is uniformly mixed with 10wt% phenolic resin binder, ethanol is added as a solvent, and stirred to form a slurry (50% concentration). The slurry is poured into a mold and pressed at 10 MPa to form a green body. The green body is first dried and solidified at 150°C, then placed in a muffle furnace and sintered at 1200°C in an oxidizing atmosphere for 3 hours. The furnace is cooled to obtain an inert anode material for aluminum electrolysis.

[0079] 2.2. Performance test of inert anode materials for aluminum electrolysis:

[0080] (1) Detection of porosity and bulk density

[0081] According to Archimedes' principle, the water displacement method is used to determine the above-mentioned inert anode materials for aluminum electrolysis.

[0082] (2) Testing of bending strength

[0083] The three-point bending method was used to determine the flexural strength of the inert anode material and then characterize its thermal shock resistance.

[0084] (2) Corrosion resistance testing

[0085] The high temperature electrolytic corrosion test is used to characterize the corrosion resistance of the inert anode material. The specific operation steps are as follows:

[0086] A comparative experiment was conducted using a carbon anode and the inert anode material prepared in Example 1. The prepared anode material sample was placed in a high-temperature electrolytic cell with cryolite-alumina molten salt as the electrolyte, a molecular ratio of 2.2, an electrolysis temperature of 950°C, and an anode current of 0.8 A / cm 2 , electrolysis time 8h, record the mass loss and surface corrosion of the anode material, and evaluate the corrosion resistance of the material by calculating the corrosion rate (CR):

[0087]

[0088] Where W is the mass loss, A is the surface area of ​​the anode material, and t is the electrolysis time.

[0089] 3. Test result analysis;

[0090] In the research and development of inert anode materials for aluminum electrolysis, comparative experiments with traditional carbon anodes and uncoated ceramic materials are a key step in verifying their performance advantages. The following is a supplementary comparative experiment design and result analysis for Example 1 in the patent.

[0091] Comparative Example 1: Traditional carbon anode

[0092] Comparative Example 2: Pure NiFe2O4 ceramic material (without HEA core layer)

[0093] Comparative Example 3: Co 0.1 Cr 0.1 Fe 0.1 Mn 0.1 Ni 0.1 High entropy alloy sintered body

[0094] Test results and analysis of Example 1 and Comparative Examples 1-3

[0095]

[0096]

[0097] Experimental conclusions and key mechanism analysis

[0098] (1) Synergistic effect of core-shell structure

[0099] The ceramic shell (NiFe2O4) in the core-shell powder material prepared in Example 1 can isolate the direct contact between the molten salt electrolyte and the HEA, inhibiting chemical corrosion; the core layer spinel structure remains stable at high temperatures, reducing oxidation caused by oxygen ion diffusion. 0.1 Cr0.1 Fe 0.1 Mn 0.1 Ni 0.1 ) The high entropy effect slows down the diffusion of elements and reduces the oxidation rate. At the same time, the high conductivity ensures uniform current distribution and avoids local overheating.

[0100] The core-shell design in this Example 1 significantly improves corrosion resistance (CR is reduced by more than 80%) and mechanical strength. The prepared aluminum electrolysis inert anode material exhibits excellent corrosion resistance under high-temperature electrolysis conditions, and the corrosion rate is much lower than that of traditional carbon anode materials, indicating that the material has good corrosion resistance and is suitable for the application of aluminum electrolysis inert anodes.

[0101] Compared with the traditional carbon anode in comparative example 1, the aluminum electrolysis inert anode prepared in this embodiment 1 is not consumed, has no CO2 emissions, and reduces energy consumption by more than 30%;

[0102] Compared with the pure ceramic anode of Comparative Example 2, the conductivity of the inert anode material for aluminum electrolysis prepared in Example 1 is improved by one order of magnitude, solving the problem of preheating of the pure ceramic anode.

[0103] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation thereto. It should be noted that those skilled in the art may make various improvements and modifications without departing from the principles of the present invention, and such improvements and modifications shall also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a spinel ceramic@HEA core-shell powder material, comprising the following steps: (1) washing the high entropy alloy powder to obtain a high entropy alloy matrix; (2) preparing a solution of metal salts according to a stoichiometric ratio, and adding a complexing agent and a precipitant dropwise into the solution to perform a coprecipitation reaction to obtain a ceramic coating phase slurry; (3) coating the ceramic coating phase in the slurry on the surface of the high entropy alloy substrate by an immersion pulling method or a spraying method to form a high entropy alloy precursor; (4) The high entropy alloy precursor is ground and sintered in sequence to obtain the spinel ceramic@HEA core-shell powder material.

2. The method for preparing the spinel ceramic@HEA core-shell powder material according to claim 1, characterized in that: The specific steps of step (2) are as follows: 1) Weigh the metal salt according to the stoichiometric ratio, dissolve it in deionized water at 80-100°C, and stir it magnetically until it is completely dissolved to prepare a solution with an ion concentration of 0.1-10 mol / L; 2) The precipitant is prepared at a molar ratio of 1.5:1 to the metal ion; the complexing agent is prepared at a molar ratio of 1:0.1 to 3 to the metal ion, the water bath temperature is controlled at 20 to 30° C., 0.5 to 2 wt % of a dispersant is added, and the precipitant and complexing agent are dripped into the metal salt solution at a rate of 1 to 2 mL / min to perform a co-precipitation reaction to obtain a ceramic coating phase slurry.

3. The method for preparing the spinel ceramic@HEA core-shell powder material according to claim 1 or 2, characterized in that: The complexing agent includes one or more of ethylenediaminetetraacetic acid, sodium pyrophosphate, ammonia water, ammonium chloride, ammonium sulfate, ammonium nitrate, ammonium citrate, ethylenediamine, acetic acid, ammonium acetate, sodium fluoride, tartaric acid, maleic acid, succinic acid, citric acid and malonic acid.

4. The method for preparing the spinel ceramic@HEA core-shell powder material according to claim 1 or 2, characterized in that: The metal salt includes one or more of cobalt salt, nickel salt, iron salt, manganese salt, aluminum salt, copper salt, magnesium salt and zinc salt; The cobalt salt comprises one or more of cobalt carbonate, cobalt chloride, cobalt nitrate, cobalt sulfate, and cobalt acetate; The nickel salt includes one or more of nickel nitrate, nickel chloride, and nickel sulfate; the iron salt includes one or more of iron nitrate, iron chloride, and iron sulfate; The manganese salt includes one or more of manganese nitrate, manganese chloride, and manganese sulfate; The aluminum salt includes one or more of aluminum nitrate, aluminum chloride, and aluminum sulfate; The copper salt includes one or more of copper nitrate, copper chloride, and copper sulfate; The magnesium salt includes one or more of magnesium chloride and magnesium sulfate; The zinc salt includes one or more of zinc chloride and zinc sulfate.

5. The method for preparing the spinel ceramic@HEA core-shell powder material according to claim 1 or 2, characterized in that: The pH value condition of the coprecipitation reaction is 8-10.

6. The method for preparing the spinel ceramic@HEA core-shell powder material according to claim 1 or 2, characterized in that: The precipitant includes one or more of ammonia water, urea, NH4HCO3, NaOH, KOH, Na2CO3, and Cu(OH)2.

7. The method for preparing the spinel ceramic@HEA core-shell powder material according to claim 1 or 2, characterized in that: The dispersant includes one or more of polyvinyl alcohol, polyvinyl pyrrolidone and sodium lauryl sulfate.

8. The method for preparing the spinel ceramic@HEA core-shell powder material according to claim 1 or 2, characterized in that: In the step (4), the sintering is carried out in an oxidizing atmosphere, the sintering heating rate is 2-20° C. / min, the sintering temperature is 500-900° C., and the sintering time is 3-30 hours.

9. The spinel ceramic@HEA core-shell powder material prepared according to the method of any one of claims 1 to 8, characterized in that: The shell thickness of the core-shell structure is 50 to 500 nm, and the molar ratio of the core layer to the shell layer is 1:0.8 to 1:1.

2.

10. An inert anode material for aluminum electrolysis, prepared by the spinel ceramic@HEA core-shell powder material prepared by the method according to any one of claims 1 to 8 or the spinel ceramic@HEA core-shell powder material according to claim 9.

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