Composite spraying material for electrolytic aluminum anode and preparation method of composite spraying material

Abstract

The invention discloses a composite spraying material for an electrolytic aluminum anode and a preparation method of the composite spraying material, and relates to the technical field of electrolytic aluminum metallurgy new materials, and the composite spraying material comprises the following components in percentage by weight: 42%-45% of aluminum-based high-entropy oxide, 18%-22% of a structure enhancer, 5%-8% of a composite glazing agent, 3%-5% of a film forming regulator, 1%-3% of a bonding system and the balance of deionized water, the aluminum-based high-entropy oxide is prepared from aluminum, iron, magnesium, copper and nickel according to the molar ratio of 0.62: 0.14: 0.04: 0.09: 0.07 through mechanical alloying and self-propagating high-temperature synthesis. The protection performance and the purity of molten aluminum are guaranteed, and the component design is more reasonable. The aluminum-based high-entropy oxide is subjected to accurate molar ratio regulation and control and matched with a structure enhancer to form a compact protection framework, the oxidation resistance is improved by 40% or above compared with a traditional aluminum oxide coating, erosion of oxygen, hydrogen fluoride and cryolite slag at the temperature of 950-1000 DEG C can be effectively resisted, core components are compatible with electrolytic raw materials, no impurity element is introduced, and the service life of the electrolytic coating is prolonged. And even if a small amount of coating falls off, molten aluminum cannot be polluted, and the quality of electrolytic products is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of new materials technology in electrolytic aluminum metallurgy, specifically to a composite spraying material for electrolytic aluminum anodes and its preparation method. Background Technology

[0002] In the electrolytic aluminum production process, prebaked carbon anodes, as core conductive components, need to operate for extended periods in a high-temperature environment of 950-1000℃, while also withstanding the corrosive effects of strong oxidizing media such as oxygen, hydrogen fluoride, and cryolite slag. Currently, carbon anode resources are becoming increasingly scarce, and trace metal elements are easily mixed into the carbon blocks, accelerating anode oxidation loss and leading to frequent problems such as anode slagging, hot bath damage, and cathode damage. This not only reduces electrolysis efficiency and increases energy consumption but also affects the purity of the molten aluminum, increasing production costs.

[0003] To address these issues, the industry commonly employs a technical solution of spraying protective coatings onto the surface of carbon anodes. Existing coating materials are mostly prepared from single base components such as alumina and aluminum ash. While the process is simple, their overall performance under complex operating conditions is insufficient. It's difficult to simultaneously achieve good high-temperature oxidation resistance, fracture toughness, and adhesion to the carbon substrate. Some patents utilize high-entropy oxides or composite fluoride salt systems to optimize coating performance. For example, aluminum-based high-entropy alloy powder is used to prepare an oxide coating to improve strength, or sodium fluoride or aluminum fluoride is added to improve corrosion resistance. However, these methods still have the following drawbacks: First, an unreasonable high-entropy oxide component ratio can easily introduce impurities that contaminate the molten aluminum, or improper melting point control can affect high-temperature stability. Second, the thermal expansion coefficients of the coating and the carbon anode are mismatched, making it prone to cracking at high temperatures, leading to protective failure.

[0004] Based on this, the development of a composite spraying material for electrolytic aluminum anodes with synergistic component optimization, high temperature corrosion resistance, strong adhesion, and simple preparation is of great significance for extending the service life of anodes and reducing the energy consumption and production cost of electrolytic aluminum. Summary of the Invention

[0005] The purpose of this invention is to provide a composite spraying material for electrolytic aluminum anodes and its preparation method, so as to solve the problems mentioned in the background art.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A composite spraying material for electrolytic aluminum anodes and its preparation method are disclosed. The material, by weight percentage, comprises the following components: 42%-45% aluminum-based high-entropy oxide, 18%-22% structural reinforcing agent, 5%-8% composite glazing agent, 3%-5% film-forming regulator, 1%-3% binder system, and the balance being deionized water. The aluminum-based high-entropy oxide is prepared by mechanical alloying and self-propagating high-temperature synthesis of aluminum, iron, magnesium, copper, and nickel in a molar ratio of 0.62:0.14:0.04:0.09:0.07.

[0007] A further improvement of the technical solution of the present invention is that the structural reinforcing agent is a mixture of quartz sand and silicon carbide particles in a mass ratio of 3:1-4:1, wherein the SiO2 content in the quartz sand is ≥99wt.% and the particle size is 5-10μm, and the particle size of the silicon carbide particles is 2-5μm.

[0008] A further improvement of the technical solution of the present invention is that the composite glazing agent is composed of potassium feldspar, talc and sodium feldspar mixed in a mass ratio of 4:3:3, with a particle size ≤15μm.

[0009] A further improvement of the technical solution of the present invention is that: the film-forming regulator is a mixture of ethyl cellulose and polydimethylsiloxane in a mass ratio of 2:1; the bonding system is a mixture of silane coupling agent KH-550 and aluminum sol in a mass ratio of 1:4-1:5.

[0010] Another solution is provided: a method for preparing a composite spraying material for electrolytic aluminum anodes, comprising the following steps: (1) Preparation of aluminum-based high-entropy oxide powder; (2) Preparation of composite glaze powder; (3) Preparation of premixed powder; (4) Prepare the spraying slurry.

[0011] A further improvement of the technical solution of the present invention is that: in step (1), the mechanical alloying ball-to-material ratio is 5:1, the rotation speed is 300-320 rpm, and the ball milling is 2.5 h; the self-propagating high-temperature synthesis is carried out under argon protection, the reaction is initiated at 650-700℃, and the temperature is maintained for 30 min.

[0012] The further improvement of the technical solution of the present invention is as follows: In step (2), potassium feldspar, talc and sodium feldspar raw materials are weighed according to the ratio, crushed in a crusher to a particle size ≤5mm, and then transferred to a ball mill. Using deionized water as the medium, the mixture is ball-milled for 4 hours, filtered, and then dried in an oven at 110℃ to constant weight. The mixture is then ground through a 300-mesh sieve to obtain composite glaze powder.

[0013] A further improvement of the technical solution of the present invention is that: in step (3), aluminum-based high-entropy oxide powder, structural reinforcing agent and composite glazing agent powder are placed in a mixer, the speed is 200 rpm, and the mixture is mixed for 1 hour to obtain a uniform premixed powder.

[0014] The further improvement of the technical solution of the present invention is as follows: in step (4), a measured amount of deionized water is added to the stirring vessel, stirring is started at 400 rpm, film-forming regulator and bonding system are added in sequence, stirring for 30 minutes until completely dissolved, and after adding premixed powder, the mixture is kept at 50-60℃ and stirred for 2 hours.

[0015] A further improvement of the technical solution of the present invention is that: step (4) further includes ultrasonic dispersion for 10 minutes every 20 minutes to eliminate agglomerates; after stirring, the mixture is cooled to room temperature and filtered through a 100-mesh sieve to remove large particulate impurities, thereby obtaining a composite spraying material slurry.

[0016] Due to the adoption of the above technical solution, the technical progress achieved by this invention compared to the prior art is as follows: This invention provides a composite coating material for electrolytic aluminum anodes and its preparation method. It achieves dual protection and ensures the purity of the molten aluminum through a more rational component design. The aluminum-based high-entropy oxide, with precise molar ratio control and combined with a structural reinforcing agent, forms a dense protective skeleton. Its oxidation resistance is improved by more than 40% compared to traditional alumina coatings. It can effectively resist the erosion of oxygen, hydrogen fluoride, and cryolite slag at 950-1000℃. Furthermore, the core components are compatible with the electrolytic raw materials, and no impurity elements are introduced. Even if a small amount of coating peels off, it will not contaminate the molten aluminum, ensuring the quality of the electrolytic product.

[0017] This invention provides a composite spraying material for electrolytic aluminum anodes and its preparation method. After the composite glazing agent is melted at high temperature, it can automatically fill the thermal expansion gap and microcracks between the coating and the carbon anode. Combined with the strong bonding effect of the adhesive system, the adhesion between the coating and the carbon substrate is increased by more than 35%, the high temperature cracking rate is reduced by 60%, the protective layer is prevented from falling off and failing, the service life of the carbon anode is extended by 15%-20%, and the frequency of anode replacement is reduced.

[0018] This invention provides a composite spraying material for electrolytic aluminum anodes and its preparation method. The simplified preparation process is suitable for industrial mass production, offering significant cost reduction and efficiency advantages. Eliminating the need for high-temperature sintering, the core components are prepared through a synergistic process of mechanical alloying and self-propagating high-temperature synthesis. Subsequent slurry preparation is simple and energy-efficient, with spraying and curing completed at room temperature. This increases production efficiency by more than 30% compared to traditional processes, while simultaneously reducing the unit energy consumption of electrolytic aluminum by 8%-10%, significantly compressing overall production costs. Attached Figure Description

[0019] Figure 1 This is a diagram illustrating the preparation of the aluminum-based high-entropy oxide of the present invention; Figure 2 This is a flowchart of the method of the present invention. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to embodiments: Example

[0021] A composite spraying material for electrolytic aluminum anodes comprises, by weight percentage: 43% aluminum-based high-entropy oxide, 20% structural reinforcing agent (quartz sand: silicon carbide = 3:1), 6% composite glazing agent (potassium feldspar: talc: sodium feldspar = 4:3:3), 4% film-forming regulator (ethyl cellulose: polydimethylsiloxane = 2:1), 2% binder system (KH-550: aluminum sol = 1:4), and 25% deionized water.

[0022] Its preparation method is as follows: 1. Preparation of aluminum-based high-entropy oxide powder: Weigh metal powder with a purity of 99.6% and a particle size of 150 mesh. The ball milling parameters are: ball-to-material ratio of 5:1, ball number ratio of 17:9:2, rotation speed of 310 rpm, and ball milling for 2.5 h. After mixing with an initiator, initiate a self-propagating reaction at 680℃ under argon protection, hold for 30 min, cool, and then grind through a 200-mesh sieve.

[0023] 2. Preparation of composite glaze powder: Weigh the raw materials according to the ratio, crush them, ball mill for 4 hours, dry them, and then grind them through a 300-mesh sieve.

[0024] 3. Premixed powder: Place aluminum-based high-entropy oxide, structural reinforcing agent and composite glazing agent in a mixer and mix at 200 rpm for 1 hour.

[0025] 4. Preparation of spray coating slurry: Add deionized water, and add film-forming regulator and binder system in sequence while stirring. Stir for 30 min. Add premixed powder, keep warm at 55℃ and stir for 2 h. Disperse with ultrasonication at intervals, and filter to obtain slurry.

[0026] The slurry was sprayed onto the surface of the carbon anode, with a coating thickness of 8 mm. After curing at room temperature for 2 hours, it was put into use in the electrolytic cell. Tests showed that the adhesion between the coating and the carbon anode reached 1.8 MPa. After 30 days of continuous use in a high-temperature environment of 980℃ and cryolite slag, the anode loss was reduced by 18% compared to the uncoated area, the unit energy consumption of electrolysis was reduced by 9%, and the purity of the aluminum liquid was not affected. Example

[0027] A composite spraying material for electrolytic aluminum anodes, by weight percentage, comprises: 45% aluminum-based high-entropy oxide, 18% structural reinforcing agent (quartz sand: silicon carbide = 4:1), 7% composite glazing agent, 3% film-forming regulator, 2.5% binder system (KH-550: aluminum sol = 1:5), and 24.5% deionized water.

[0028] The preparation method is the same as in Example 1, except that the molar ratio of aluminum-based high-entropy oxides is adjusted to 0.65:0.14:0.04:0.09:0.08, the self-propagating reaction temperature is 700℃, and the heat preservation temperature during the preparation of the spraying slurry is 60℃.

[0029] Tests showed that the coating adhesion reached 1.9 MPa, the anode loss was reduced by 19.5% under high-temperature corrosion environment, the unit energy consumption of electrolysis was reduced by 9.5%, and the coating showed no obvious cracks or peeling. Example

[0030] Comparative Example The coating material was prepared using existing technology, with the following components: 40% alumina, 15% sodium fluoride, 15% aluminum fluoride, 3% metallic aluminum powder, 12% water glass, 4% sodium bentonite, and 11% deionized water. The slurry was prepared and sprayed using conventional processes. Testing showed that the coating adhesion was 0.9 MPa, but noticeable cracks appeared after 20 days of use at high temperatures. The anode loss was 22% higher than in Example 1, and the unit energy consumption for electrolysis was 10% higher.

[0031] The present invention has been described in detail above. However, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, any modifications or improvements that do not depart from the spirit of the present invention are within the scope of protection of the present invention.

Claims

1. A composite spraying material for electrolytic aluminum anodes, characterized in that: The product, by weight percentage, comprises the following components: 42%-45% aluminum-based high-entropy oxide, 18%-22% structural reinforcing agent, 5%-8% composite glazing agent, 3%-5% film-forming regulator, 1%-3% binder system, and the balance being deionized water. The aluminum-based high-entropy oxide is prepared by mechanical alloying and self-propagating high-temperature synthesis of aluminum, iron, magnesium, copper, and nickel in a molar ratio of 0.62:0.14:0.04:0.09:0.

07.

2. The composite spraying material for electrolytic aluminum anodes according to claim 1, characterized in that: The structural reinforcing agent is a mixture of quartz sand and silicon carbide particles in a mass ratio of 3:1 to 4:

1. The quartz sand contains ≥99wt.% SiO2 with a particle size of 5-10μm, and the silicon carbide particles have a particle size of 2-5μm.

3. The composite spraying material for electrolytic aluminum anodes according to claim 1, characterized in that: The composite glazing agent is composed of potassium feldspar, talc, and sodium feldspar mixed in a mass ratio of 4:3:3, with a particle size ≤15μm.

4. The composite spraying material for electrolytic aluminum anodes according to claim 1, characterized in that: The film-forming regulator is a mixture of ethyl cellulose and polydimethylsiloxane in a mass ratio of 2:1; the bonding system is a mixture of silane coupling agent KH-550 and aluminum sol in a mass ratio of 1:4-1:

5.

5. A method for preparing the composite spraying material according to any one of claims 1-4, characterized in that, Includes the following steps: (1) Preparation of aluminum-based high-entropy oxide powder; (2) Preparation of composite glaze powder; (3) Preparation of premixed powder; (4) Prepare the spraying slurry.

6. The method for preparing a composite spraying material for electrolytic aluminum anodes according to claim 5, characterized in that: In step (1), the mechanical alloying ball-to-material ratio is 5:1, the rotation speed is 300-320 rpm, and the ball milling is carried out for 2.5 hours; the self-propagating high-temperature synthesis is carried out under argon protection, the reaction is initiated at 650-700℃, and the temperature is maintained for 30 minutes.

7. The method for preparing a composite spraying material for electrolytic aluminum anodes according to claim 5, characterized in that: In step (2), potassium feldspar, talc and sodium feldspar raw materials are weighed according to the ratio, crushed in a crusher until the particle size is ≤5mm, then transferred to a ball mill, ball milled for 4 hours with deionized water as the medium, filtered and dried in an oven at 110℃ until constant weight, and ground through a 300-mesh sieve to obtain composite glaze powder.

8. The method for preparing a composite spraying material for electrolytic aluminum anodes according to claim 5, characterized in that: In step (3), aluminum-based high-entropy oxide powder, structural reinforcing agent, and composite glazing agent powder are placed in a mixer and mixed at 200 rpm for 1 hour to obtain a uniform premixed powder.

9. A method for preparing a composite spraying material for electrolytic aluminum anodes according to claim 5, characterized in that: In step (4), a measured amount of deionized water is added to the mixing vessel, stirring is started at 400 rpm, and film-forming regulator and binder are added in sequence. Stirring is carried out for 30 minutes until completely dissolved. After adding the premixed powder, the mixture is kept at 50-60℃ and stirred for 2 hours.

10. A method for preparing a composite spraying material for electrolytic aluminum anodes according to claim 5, characterized in that: The step (4) also includes ultrasonic dispersion for 10 minutes every 20 minutes to eliminate agglomerates; after stirring, cooling to room temperature and filtering through a 100-mesh sieve to remove large particulate impurities to obtain composite spraying material slurry.

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