Sandwich structure erosion-resistant layer for aluminum electrolysis, preparation method and erosion-resistant material

Abstract

The invention provides a sandwich structure erosion-resistant layer for aluminum electrolysis, a preparation method of the sandwich structure erosion-resistant layer and an erosion-resistant material, and belongs to the field of aluminum electrolysis. The erosion-resistant layer with the sandwich structure comprises a bonding layer, a coating layer and a coating layer, wherein the bonding layer covers the surface of a base material for aluminum electrolysis; the stabilizing layer covers the surface of the bonding layer; and the functional layer covers the surface of the stable layer. By reasonably designing a composite structure and a powder material of the erosion-resistant layer of the sandwich structure, the bonding layer and the stable layer are matched through thermal expansion coefficient gradients, and the interface cracking risk under thermal circulation is reduced; and meanwhile, the bonding layer isolates matrix corrosion, the stabilizing layer strengthens interface bonding, the functional layer provides active protection, a three-stage protection system is formed, the problem that a traditional single coating loses efficacy when resisting multiple corrosion is solved, and when the coating is applied to the field of aluminum electrolysis, the service life of a matrix material can be prolonged, and the integrity and performance stability of the matrix material can be kept.

Description

Technical Field

[0001] The present application relates to the technical field of aluminum electrolysis, and in particular to a sandwich structure corrosion-resistant layer for aluminum electrolysis, a preparation method thereof, and a corrosion-resistant material. Background Art

[0002] In aluminum electrolysis production, cathode carbon blocks and cathode steel rods are key components of the electrolytic cell. However, they are exposed to a harsh environment of high temperatures (950°C to 970°C), highly corrosive electrolytes (containing fluorides, alumina, etc.), and molten aluminum. This leads to significant corrosion problems. Specifically, under the action of electric current, the molten aluminum and the cathode carbon blocks undergo electrochemical corrosion or chemical reactions, generating aluminum carbide (Al4C3) that is soluble in the molten aluminum, forming pits or cracks. Intensified corrosion in the cracks can lead to crack expansion. Simultaneously, sodium penetrates the carbon blocks and reacts with the electrolyte, causing volume expansion, leading to cathode bulging and steel rod bending, which affects the stability of the electrolytic cell and the pole-changing operation. Furthermore, electrolyte and molten aluminum can penetrate the cathode steel rod through cracks, pores, or ramming joints, causing iron to dissolve into the molten aluminum, increasing the original aluminum-iron content and, in severe cases, causing tank leakage accidents.

[0003] Currently, cathode material protection is primarily achieved through coating technology, but this has the following drawbacks: Cryolite coatings, which form a protective layer by infiltrating molten cryolite into the pores of the carbon anode, can inhibit oxidation by O₂ and CO₂, but the coating thickness is limited and it lacks resistance to corrosion from hydrogen fluoride gas and electrolytes. Composite coatings (such as TiB₂ / fluorinated graphene / CNT) leverage the corrosion resistance of fluorinated graphene and the reinforcing effect of CNTs to improve mechanical properties, but the CNT copper plating process is complex and costly, and the coating easily falls off, making long-term reliability insufficient. Therefore, improving the corrosion resistance of cathode materials for aluminum electrolysis is an urgent technical challenge. Summary of the Invention

[0004] The present application provides a sandwich structure corrosion-resistant layer for aluminum electrolysis, a preparation method, and a corrosion-resistant material to solve the following technical problem: how to improve the corrosion resistance of cathode materials for aluminum electrolysis.

[0005] In a first aspect, an embodiment of the present application provides a sandwich structure corrosion-resistant layer for aluminum electrolysis, wherein the sandwich structure corrosion-resistant layer comprises:

[0006] An adhesive layer covering the surface of the aluminum electrolysis base material, wherein the powder material of the adhesive layer includes one or more of titanium nitride, titanium tungsten, tantalum nitride, graphene, tungsten carbide, and metal nanowires;

[0007] a stabilizing layer, the stabilizing layer covering the surface of the bonding layer, the powder material of the stabilizing layer comprising: one or more of titanium diboride, titanium nitride, metal nanowires, nickel powder, nickel-based alloy powder, iron powder, and iron-based alloy powder; and

[0008] A functional layer covers the surface of the stabilizing layer, and the powder material of the functional layer includes one or more of titanium diboride, aluminum oxide, zirconium oxide, graphene, aluminum powder, silicon carbide and tungsten carbide.

[0009] Optionally, the thickness of the adhesive layer is 10 μm to 500 μm.

[0010] Optionally, the thickness of the stabilization layer is 20 μm to 300 μm.

[0011] Optionally, the thickness of the functional layer is 100 μm to 1600 μm.

[0012] Optionally, the powder material of the bonding layer is spherical or nearly spherical in shape, and has a particle size of 10 μm to 120 μm;

[0013] The powder material of the stabilization layer is spherical or nearly spherical in shape, and has a particle size of 10 μm to 120 μm;

[0014] The powder material of the functional layer is spherical or nearly spherical in shape, and has a particle size of 10 μm to 120 μm.

[0015] In a second aspect, an embodiment of the present application provides a method for preparing the erosion-resistant layer of the sandwich structure according to any one of the embodiments of the first aspect, the method comprising:

[0016] pre-treating the base material to obtain a pre-treated base material;

[0017] Screening the powder material of the bonding layer, the powder material of the stabilizing layer and the powder material of the functional layer;

[0018] The powder material of the bonding layer, the powder material of the stabilization layer and the powder material of the functional layer are sequentially coated on the surface of the pretreated base material to form a sandwich structure corrosion-resistant layer on the surface of the pretreated base material.

[0019] Optionally, the sieve adopts one or more of an air jet screening method, a cyclone separator screening method, a laser particle size screening method and a manual screening method;

[0020] The coating is carried out by one or more of sputtering deposition, ion plating, pulsed laser deposition, plasma spraying, arc spraying and flame spraying.

[0021] In a third aspect, an embodiment of the present application provides a corrosion-resistant material for aluminum electrolysis, wherein the corrosion-resistant material:

[0022] Matrix materials for aluminum electrolysis;

[0023] The sandwich structure erosion-resistant layer described in any one of the embodiments of the first aspect is covered on the surface of the base material, and the bonding layer of the sandwich structure erosion-resistant layer is arranged adjacent to the base material.

[0024] Optionally, the matrix material includes one or more of: carbon material, metal material, alloy material, ceramic material and metal-ceramic composite material.

[0025] Optionally, the weight loss rate of the corrosion-resistant material after being immersed in molten aluminum liquid for 120 minutes is ≤5%.

[0026] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0027] An embodiment of the present application provides a sandwich structure corrosion-resistant layer for aluminum electrolysis, which includes: an adhesive layer, the adhesive layer covering the surface of a base material for aluminum electrolysis, the powder material of the adhesive layer including: one or more of titanium nitride, titanium tungsten, tantalum nitride, graphene, tungsten carbide and metal nanowires; a stabilization layer, the stabilization layer covering the surface of the adhesive layer, the powder material of the stabilization layer including: one or more of titanium diboride, titanium nitride, metal nanowires, nickel powder, nickel-based alloy powder, iron powder and iron-based alloy powder; and a functional layer, the functional layer covering the surface of the stabilization layer, the powder material of the functional layer including: one or more of titanium diboride, aluminum oxide, zirconium oxide, graphene, aluminum powder, silicon carbide and tungsten carbide. By rationally designing the composite structure and powder material of the sandwich structure's corrosion-resistant layer, the bonding layer and the stabilizing layer are matched through a gradient of thermal expansion coefficients to reduce the risk of interface cracking under thermal cycling. At the same time, the bonding layer isolates the substrate from corrosion, the stabilizing layer strengthens the interface bonding, and the functional layer provides active protection, forming a three-level protection system to solve the problem of traditional single coating failure in resisting multiple corrosion. In addition, metal nanowires (bonding layer) and graphene (functional layer) form a three-dimensional reinforced network to improve the overall mechanical properties of the coating. Nickel-based alloy (stabilizing layer) and tungsten carbide (functional layer) work together to resist high-temperature molten salt erosion. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0029] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0030] Figure 1A schematic structural diagram of a sandwich structure corrosion-resistant layer for aluminum electrolysis provided in an embodiment of the present application;

[0031] Figure 2 A schematic flow chart of a method for preparing a corrosion-resistant layer of a sandwich structure for aluminum electrolysis provided in an embodiment of the present application;

[0032] Reference numerals:

[0033] 1-base material, 2-sandwich structure corrosion resistant layer, 21-adhesive layer, 22-stabilizing layer, 23-functional layer. DETAILED DESCRIPTION

[0034] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0035] The range descriptions described in this article, such as numerical ranges, ratio ranges, etc., include all possible sub-ranges and single numerical values ​​within the range. For example, the range description of "1 to 6" or "1~6" covers all sub-ranges from 1 to 6 (such as 1 to 3, 2 to 5, etc.) and single numbers (such as 1, 2, 3, 4, 5, 6). Unless otherwise specified, the terms "including", "comprising", etc. used in this article mean "including but not limited to"; relational terms such as "first" and "second" are only used to distinguish different entities or operations, and do not imply an actual sequence or association relationship; "and / or" means that multiple situations can exist alone or at the same time; expressions such as "at least one", "multiple", and "at least one" refer to any combination of corresponding objects, including a combination of single or multiple objects. The proportional relationships involved in the article, such as mass ratios, molar ratios, etc., should be understood as the corresponding relationship between the first and second terms of the proportional formula in the order of description. The raw materials, reagents, instruments and equipment used in this article can be purchased on the market or prepared by existing methods.

[0036] Figure 1 A schematic structural diagram of a sandwich structure corrosion-resistant layer for aluminum electrolysis provided in an embodiment of the present application.

[0037] like Figure 1 As shown, the embodiment of the present application provides a sandwich structure corrosion-resistant layer for aluminum electrolysis, and the sandwich structure corrosion-resistant layer includes:

[0038] An adhesive layer covering the surface of the aluminum electrolysis base material, wherein the powder material of the adhesive layer includes one or more of titanium nitride, titanium tungsten, tantalum nitride, graphene, tungsten carbide, and metal nanowires;

[0039] a stabilizing layer, the stabilizing layer covering the surface of the bonding layer, the powder material of the stabilizing layer comprising: one or more of titanium diboride, titanium nitride, metal nanowires, nickel powder, nickel-based alloy powder, iron powder, and iron-based alloy powder; and

[0040] A functional layer covers the surface of the stabilizing layer, and the powder material of the functional layer includes one or more of titanium diboride, aluminum oxide, zirconium oxide, graphene, aluminum powder, silicon carbide and tungsten carbide.

[0041] It should be noted that the reasons for selecting the powder material of the bonding layer are:

[0042] Titanium nitride, titanium tungsten, and tantalum nitride: high hardness, resistant to molten salt corrosion, forming a strong chemical bond with the substrate through metallurgical bonding (such as diffusion welding), while its own chemical stability can prevent the invasion of corrosive media.

[0043] Graphene and tungsten carbide: The two-dimensional layer structure of graphene can fill interface microcracks and disperse local stress; the high wear resistance of tungsten carbide can enhance the interface's anti-erosion ability.

[0044] Metal nanowires: Physically connect the substrate and coating through the "bridging" effect, improving the mechanical bonding strength. At the same time, the nanoscale size can fill the micron-scale pores and reduce the probability of corrosion channel formation.

[0045] Thus, the bonding layer strengthens the bond strength between the substrate (such as cathode carbon blocks or steel rods) and the coating through mechanical or metallurgical bonding, relieves stress caused by differences in thermal expansion coefficients, and prevents corrosive media from penetrating through interface defects. At the same time, cermets such as titanium nitride (TiN) and titanium tungsten (TiW) have high melting points (>2000°C) and low thermal expansion coefficients (similar to carbon-based materials), effectively blocking the penetration of fluorides and molten aluminum while providing electrical conductivity.

[0046] Reasons for choosing powder material for stabilization layer:

[0047] Titanium diboride and titanium nitride: They have strong high-temperature stability (melting point > 2800°C), and their thermal expansion coefficient is highly compatible with the aluminum electrolytic matrix (such as carbon blocks), which can reduce the accumulation of thermal stress under temperature fluctuations.

[0048] Nickel powder, nickel-based alloy powder, iron powder, iron-based alloy powder: good ductility and toughness, can buffer interfacial stress through plastic deformation; alloy components (such as Ni-Cr alloy) can form an oxidation protective layer to improve resistance to high-temperature oxidation.

[0049] Metal nanowires: Similar to the nanowires in the adhesive layer, they enhance the mechanical interlocking between layers while filling the pores between layers and improving the density of the coating.

[0050] Therefore, the stabilization layer achieves a transition in thermal expansion coefficient between the bonding layer and the functional layer through a composition gradient design (such as titanium diboride and nickel-based alloy), avoiding cracking or spalling caused by interfacial stress concentration. At the same time, nickel powder and nickel-based alloys form a stable oxide film (such as NiO) at high temperatures, resisting corrosion from fluoride and sodium vapor.

[0051] Reasons for selecting powder material for functional layer:

[0052] Titanium diboride: It has both high conductivity (reducing electrolysis energy consumption) and resistance to molten salt corrosion. It is often used in the cathode coating of aluminum electrolysis cells and can form a passivation film to prevent fluoride ion penetration.

[0053] Alumina and zirconium oxide: high hardness (Mohs hardness level 9), strong chemical inertness, forming a physical barrier to isolate corrosive media, while the phase change toughening effect of zirconium oxide can improve the coating's resistance to cracking.

[0054] Graphene, silicon carbide, and tungsten carbide: The stacked structure of graphene can delay the diffusion of corrosive media; the high wear resistance of SiC and WC can resist the flow and erosion of molten aluminum and extend the life of the coating.

[0055] Aluminum powder: Excellent electrical conductivity, can optimize the current distribution in the electrolytic cell and reduce coating failure caused by local overheating.

[0056] The functional layer, made of high-hardness materials such as aluminum oxide and silicon carbide, forms a dense protective layer, preventing direct contact between the fluoride melt and the aluminum liquid, thereby inhibiting electrochemical corrosion and mechanical erosion. At the same time, some materials (such as graphene and titanium diboride) can enhance conductivity and optimize electrolysis efficiency.

[0057] The synergistic effects of the various layers of the sandwich structure's corrosion-resistant layer are as follows:

[0058] (1) Stress gradient design: The bonding layer and the stabilizing layer are matched by a thermal expansion coefficient gradient (e.g., TiN→TiB2→SiC) to reduce the risk of interface cracking under thermal cycling.

[0059] (2) Functional complementarity: the bonding layer isolates the substrate from corrosion, the stabilizing layer strengthens the interface bonding, and the functional layer provides active protection, forming a three-level protection system to solve the problem of traditional single coating failure in resisting multiple corrosion.

[0060] (3) Synergistic enhancement of materials: Metal nanowires (adhesive layer) and graphene (functional layer) form a three-dimensional reinforcement network to improve the overall mechanical properties of the coating; nickel-based alloy (stabilization layer) and tungsten carbide (functional layer) work together to resist high-temperature molten salt erosion.

[0061] In some embodiments, the thickness of the adhesive layer is 10 μm to 500 μm.

[0062] The bonding layer alleviates thermal stress through mechanical or metallurgical bonding, avoids the formation of corrosion channels, and enhances the bonding strength with the substrate. If the bonding layer thickness is less than 10μm, the interface bonding area is small, and stress concentration can easily lead to coating peeling. If the bonding layer thickness is greater than 500μm, the accumulated stress due to its own weight and thermal expansion increases, which in turn reduces the bonding strength. For example, the thickness of the bonding layer can be 10μm, 25μm, 50μm, 100μm, 200μm, 300μm, 400μm, 500μm, etc.

[0063] In some embodiments, the thickness of the stabilization layer is 20 μm to 300 μm.

[0064] The stabilization layer reduces interlayer stress concentration and inhibits interface failure through composition adjustment. If the stabilization layer thickness is less than 20μm, it cannot effectively buffer thermal stress and the interface is prone to cracking. If the stabilization layer thickness is greater than 300μm, the thermal conductivity differences of the materials themselves accumulate, causing residual stress to exceed the critical value and triggering interlayer delamination. Exemplary thicknesses of the stabilization layer can be 20μm, 50μm, 100μm, 200μm, 250μm, 300μm, etc.

[0065] In some embodiments, the thickness of the functional layer is 100 μm to 1600 μm.

[0066] The functional layer can form a physical barrier, isolate the corrosive medium, and slow down the corrosion rate. The three layers complement each other and can greatly enhance the corrosion resistance. If the thickness of the functional layer is less than 100μm, the barrier effect is weak and the corrosive medium can easily penetrate into the stable layer; if the thickness of the functional layer is greater than 1600μm, the coating weight increases, and the internal stress distribution is uneven, which is easy to delaminate and peel off. For example, the thickness of the functional layer can be 200μm, 300μm, 400μm, 500μm, 1000μm, 1200μm, 1500μm, 1600μm, etc.

[0067] In some embodiments, the powder material of the bonding layer is spherical or nearly spherical in shape, and has a particle size of 10 μm to 120 μm;

[0068] The powder material of the stabilization layer is spherical or nearly spherical in shape, and has a particle size of 10 μm to 120 μm;

[0069] The powder material of the functional layer is spherical or nearly spherical in shape, and has a particle size of 10 μm to 120 μm.

[0070] Each layer of powder is spherical or nearly spherical, resulting in low porosity and high density when stacked, which reduces the penetration path of corrosive media. Furthermore, the spherical particles have a large contact area, resulting in a strong mechanical interlocking effect between layers, improving overall structural stability. For example, the particle sizes of the powder materials for the bonding layer, the stabilization layer, and the functional layer are 10μm, 20μm, 40μm, 60μm, 80μm, 100μm, 120μm, etc.

[0071] In some embodiments, the metal nanowires include one or more of silver nanowires, copper nanowires, molybdenum nanowires, and nickel-based alloy nanowires.

[0072] Figure 2 A schematic flow chart of a method for preparing a corrosion-resistant layer of a sandwich structure for aluminum electrolysis provided in an embodiment of the present application.

[0073] Based on a general inventive concept, such as Figure 2 As shown, an embodiment of the present application provides a method for preparing the erosion-resistant layer of the sandwich structure according to any one embodiment of the first aspect, the method comprising:

[0074] S1, pretreating the base material to obtain a pretreated base material;

[0075] S2. Screening powder materials for the bonding layer, the stabilizing layer, and the functional layer;

[0076] S3. Sequentially apply the powder material of the bonding layer, the powder material of the stabilization layer, and the powder material of the functional layer on the surface of the pretreated base material to form a sandwich structure corrosion-resistant layer on the surface of the pretreated base material.

[0077] In some embodiments, the sieving method adopts one or more of air jet screening method, cyclone separator screening method, laser particle size screening method and manual screening method;

[0078] The coating is carried out by one or more of sputtering deposition, ion plating, pulsed laser deposition, plasma spraying, arc spraying and flame spraying.

[0079] In some embodiments, the pretreatment steps include processing and shaping the base material, pre-treating the shaped substrate, and secondary processing of the shaped substrate.

[0080] In some embodiments, the forming substrate pretreatment method is one or more of sandpaper polishing, shot blasting, sand washing and heat treatment.

[0081] In some embodiments, the secondary treatment method of the formed substrate is one or more of alcohol cotton wiping, acetone cotton wiping, alcohol vibration cleaning, and acetone vibration cleaning.

[0082] The product prepared by the method for preparing the sandwich structure erosion-resistant layer is the above-mentioned sandwich structure erosion-resistant layer. The chemical composition and structure of the sandwich structure erosion-resistant layer prepared by the method for preparing the sandwich structure erosion-resistant layer can refer to the above-mentioned embodiment. Since the method for preparing the sandwich structure erosion-resistant layer adopts part or all of the technical solutions of the sandwich structure erosion-resistant layer embodiment, it at least has all the beneficial effects brought by the technical solutions of the sandwich structure erosion-resistant layer embodiment, which will not be repeated here.

[0083] Based on a general inventive concept, an embodiment of the present application provides a corrosion-resistant material for aluminum electrolysis, wherein the corrosion-resistant material:

[0084] Matrix materials for aluminum electrolysis;

[0085] The sandwich structure erosion-resistant layer described in any one of the above embodiments covers the surface of the base material, and the bonding layer of the sandwich structure erosion-resistant layer is arranged adjacent to the base material.

[0086] In some embodiments, the matrix material includes one or more of a carbon material, a metal material, an alloy material, a ceramic material, and a metal-ceramic composite material.

[0087] In some embodiments, the weight loss rate of the corrosion-resistant material after immersion in molten aluminum liquid for 120 minutes is ≤5%.

[0088] The corrosion-resistant material prepared in this application is not easily corroded by molten aluminum or molten electrolyte. Its application in the field of aluminum electrolysis can extend the service life of the base material, maintain the integrity and performance stability of the base material, reduce the frequency of base material repair or replacement, and reduce the cost of material replacement. Furthermore, the application of corrosion-resistant materials in the field of aluminum electrolysis can improve the purity and performance of aluminum products, enhance the operating efficiency and production efficiency of aluminum electrolysis, and thus enhance the economic benefits of enterprises.

[0089] In summary, this application, through the technical path of "multi-layer structure design - nanocomposite reinforcement - precise process control", has achieved multi-dimensional breakthroughs in bonding strength, corrosion resistance, thermal stability and conductivity of the corrosion-resistant layer for aluminum electrolysis. The core advantages are summarized as follows:

[0090] 1. Systematic advantages of multi-layer structure design

[0091] (1) Construction of a three-level protection system: the bonding layer (bottom layer) blocks the corrosion channel of the substrate, the stabilization layer (middle layer) buffers thermal stress, and the functional layer (surface layer) resists the corrosive medium, forming a full chain protection of "interface bonding-stress management-surface protection" to solve the problem of insufficient corrosion resistance of traditional single coatings.

[0092] (2) Thermal stress gradient control: The thermal expansion coefficient gradient of each layer of material is matched (such as TiN→TiB2→Al2O3), and the overall thermal expansion coefficient fluctuation is close to that of the graphite matrix, which significantly reduces the risk of thermal shock cracking.

[0093] 2. Synergistic Advantages of Material Systems

[0094] (1) Composite of nano-reinforced phase and functional materials: Nanomaterials such as graphene and metal nanowires are composited with ceramic / metal matrices. Graphene two-dimensional sheets fill microcracks and block the diffusion path of corrosive media; metal nanowires enhance the interlayer bonding strength through the "bridging effect" while reducing the porosity of the coating.

[0095] (2) Integration of conductivity and corrosion resistance: Materials such as titanium diboride and aluminum powder have both high conductivity and resistance to molten salt corrosion, which can reduce the voltage of the electrolytic cell while preventing fluoride ion penetration.

[0096] 3. Accurate matching of process parameters and structural design

[0097] (1) Thickness quantitative control: Adhesive layer (10μm~500μm): ensures the balance between interface bonding area and stress, and the bonding strength reaches its peak at 25μm; the thermal stress buffering efficiency of the stabilization layer (20μm~300μm) exceeds 70%, avoiding interlayer peeling; the functional layer (100μm~1600μm) has good corrosion resistance and penetration ability, and the self-weight and stress distribution are balanced.

[0098] (2) Optimization of spherical powder morphology: Each layer of powder is spherical or nearly spherical (particle size 10μm to 120μm), and the stacking density is improved: the penetration path of the corrosive medium is reduced, and the mechanical interlocking effect between layers is enhanced.

[0099] 4. Performance indicators and engineering application advantages

[0100] Leading corrosion resistance: after immersion in molten aluminum for 120 minutes, the weight loss rate is ≤5%, which is significantly better than traditional coatings (weight loss rate > 15%).

[0101] 5. Universality and reliability of the preparation process

[0102] (1) Diversified preparation methods: The coating process is compatible with industrial technologies such as plasma spraying and arc spraying, with a powder utilization rate of >85% and a coating uniformity error of <±5%. The pretreatment process (sandpaper polishing and acetone cleaning) removes oil and oxide layers on the substrate surface to ensure defect-free interface bonding.

[0103] (2) Strong matrix adaptability: Applicable to various matrices such as carbon materials, metal ceramics, etc., and the thermal expansion coefficient and surface properties of different matrices can be matched by adjusting the composition.

[0104] The present application will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present application only and are not intended to limit the scope of the present application. The experimental methods in the following examples where specific conditions are not specified are generally measured according to industry standards. If there are no corresponding industry standards, then the methods are carried out according to general international standards, conventional conditions, or the conditions recommended by the manufacturer.

[0105] Example 1

[0106] This embodiment provides a sandwich structure corrosion-resistant layer for aluminum electrolysis, the sandwich structure corrosion-resistant layer comprising:

[0107] An adhesive layer, the adhesive layer covers the surface of the carbon block, the powder material of the adhesive layer is titanium nitride; the thickness of the adhesive layer is 50 μm; the powder material of the adhesive layer is spherical or nearly spherical in shape, and has a particle size of 35 μm (±5 μm);

[0108] a stabilizing layer covering the surface of the bonding layer, wherein the powder material of the stabilizing layer comprises titanium diboride and titanium nitride in a mass ratio of 11:10; the thickness of the stabilizing layer is 50 μm; the powder material of the stabilizing layer is spherical or nearly spherical in shape, and has a particle size of 35 μm (±5 μm);

[0109] A functional layer covers the surface of the stabilizing layer. The powder material of the functional layer is titanium diboride. The thickness of the functional layer is 100 μm. The powder material of the functional layer is spherical or nearly spherical in shape and has a particle size of 35 μm (±5 μm).

[0110] Based on the above-mentioned sandwich structure corrosion-resistant layer for aluminum electrolysis, this embodiment also provides a method for preparing the sandwich structure corrosion-resistant layer, the method comprising:

[0111] S11, polishing a carbon block (Φ45 mm × 20 mm) with sandpaper and wiping with alcohol cotton to obtain a pretreated matrix material;

[0112] S21. Manually screening the powder material of the bonding layer, the powder material of the stabilization layer, and the powder material of the functional layer;

[0113] S31. Plasma spray the powder material of the bonding layer, the powder material of the stabilization layer and the powder material of the functional layer on the surface of the pretreated base material in sequence to form a sandwich structure corrosion-resistant layer on the surface of the pretreated base material to obtain a corrosion-resistant material.

[0114] The corrosion-resistant material weighed 63.51 g, and was then placed in molten aluminum liquid and soaked for 20 minutes, 40 minutes, 60 minutes, and 120 minutes respectively. The weighed weights were 63.24 g, 62.97 g, 61.61 g, and 60.99 g respectively. After 120 minutes, the weight loss rate of the material was 3.97%.

[0115] Example 2

[0116] The method for preparing the sandwich structure corrosion-resistant layer of Example 1 is used to form a sandwich structure corrosion-resistant layer on the surface of another carbon block.

[0117] The corrosion-resistant material weighed 63.77 g, and was then placed in a molten aluminum electrolyte and soaked for 20 min, 40 min, 60 min, and 120 min, respectively, and then taken out and weighed. The weighed weights were 63.43 g, 63.02 g, 62.64 g, and 61.17 g, respectively. After 120 min, the weight loss rate of the material was 4.08%.

[0118] Example 3

[0119] This embodiment provides a sandwich structure corrosion-resistant layer for aluminum electrolysis, the sandwich structure corrosion-resistant layer comprising:

[0120] An adhesive layer, the adhesive layer covering the surface of the carbon steel block, the powder material of the adhesive layer being silver nanowires; the thickness of the adhesive layer being 10 μm; the powder material of the adhesive layer being spherical or nearly spherical in shape, and having a particle size of 45 μm (±5 μm);

[0121] A stabilizing layer, the stabilizing layer covering the surface of the bonding layer, the powder material of the stabilizing layer being nickel powder; the thickness of the stabilizing layer being 50 μm; the powder material of the stabilizing layer being spherical or nearly spherical in shape, and having a particle size of 45 μm (±5 μm);

[0122] A functional layer covers the surface of the stabilizing layer, wherein the powder material of the functional layer is tungsten carbide; the thickness of the functional layer is 220 μm; the shape of the powder material of the functional layer is spherical or nearly spherical, and the particle size is 45 μm (±5 μm).

[0123] Based on the above-mentioned sandwich structure corrosion-resistant layer for aluminum electrolysis, this embodiment also provides a method for preparing the sandwich structure corrosion-resistant layer, the method comprising:

[0124] S11, sandblasting and wiping a carbon steel block (50 mm × 70 mm × 2 mm) with acetone to obtain a pretreated base material;

[0125] S21. Screening the powder material of the bonding layer, the powder material of the stabilization layer, and the powder material of the functional layer using a laser particle size screening method;

[0126] S31. Sequentially ion-plate the powder material of the bonding layer, the powder material of the stabilization layer, and the powder material of the functional layer on the surface of the pretreated base material to form a sandwich structure corrosion-resistant layer on the surface of the pretreated base material to obtain a corrosion-resistant material.

[0127] The corrosion-resistant material weighed 57.36 g and was then placed in molten aluminum liquid and soaked for 20 minutes, 40 minutes, 60 minutes, and 120 minutes, and then taken out and weighed. The weighed weights were 57.17 g, 57.08 g, 56.91 g, and 56.75 g, respectively. After 120 minutes, the weight loss rate of the material was 1.06%.

[0128] Example 4

[0129] The method for preparing the sandwich structure corrosion-resistant layer of Example 3 was used to form a sandwich structure corrosion-resistant layer on the surface of another carbon steel block.

[0130] The corrosion-resistant material weighed 58.71 g, and was then placed in a molten aluminum electrolyte and soaked for 20 min, 40 min, 60 min, and 120 min, respectively, and then taken out and weighed. The weighed weights were 58.53 g, 58.49 g, 58.31 g, and 57.84 g, respectively. After 120 min, the weight loss rate of the material was 1.48%.

[0131] Example 5

[0132] This embodiment provides a sandwich structure corrosion-resistant layer for aluminum electrolysis, the sandwich structure corrosion-resistant layer comprising:

[0133] An adhesive layer, the adhesive layer covering the surface of the titanium boride ceramic block, the powder material of the adhesive layer being tantalum nitride; the thickness of the adhesive layer being 50 μm; the powder material of the adhesive layer being spherical or nearly spherical in shape, and having a particle size of 50 μm (±5 μm);

[0134] A stabilizing layer, the stabilizing layer covering the surface of the bonding layer, the powder material of the stabilizing layer being titanium nitride; the thickness of the stabilizing layer being 50 μm; the powder material of the stabilizing layer being spherical or nearly spherical in shape, and having a particle size of 50 μm (±5 μm);

[0135] A functional layer covers the surface of the stabilizing layer. The powder material of the functional layer is titanium diboride. The thickness of the functional layer is 320 μm. The powder material of the functional layer is spherical or nearly spherical in shape and has a particle size of 50 μm (±5 μm).

[0136] Based on the above-mentioned sandwich structure corrosion-resistant layer for aluminum electrolysis, this embodiment also provides a method for preparing the sandwich structure corrosion-resistant layer, the method comprising:

[0137] S11, shot blasting and wiping with alcohol cotton on a titanium boride ceramic block (30 mm × 60 mm × 10 mm) to obtain a pretreated base material;

[0138] S21. Manually screening the powder material of the bonding layer, the powder material of the stabilization layer, and the powder material of the functional layer;

[0139] S31. Plasma spray the powder material of the bonding layer, the powder material of the stabilization layer and the powder material of the functional layer on the surface of the pretreated base material in sequence to form a sandwich structure corrosion-resistant layer on the surface of the pretreated base material to obtain a corrosion-resistant material.

[0140] The corrosion-resistant material weighed 83.27 g, and was then placed in molten aluminum liquid and soaked for 20 minutes, 40 minutes, 60 minutes, and 120 minutes respectively. The weighed weights were 83.18 g, 83.11 g, 83.04 g, and 82.78 g respectively. After 120 minutes, the weight loss rate of the material was 0.59%.

[0141] Example 6

[0142] The method for preparing the sandwich structure erosion-resistant layer of Example 5 was used to form a sandwich structure erosion-resistant layer on the surface of another titanium boride ceramic block.

[0143] The corrosion-resistant material weighed 84.16 g, and was then placed in a molten aluminum electrolyte and soaked for 20 min, 40 min, 60 min, and 120 min, respectively, and then taken out and weighed. The weighed weights were 84.09 g, 83.96 g, 83.77 g, and 83.53 g, respectively. After 120 min, the weight loss rate of the material was 0.75%.

[0144] Comparative Example 1

[0145] This comparative example is modified as follows based on Example 5:

[0146] The sandwich structure erosion-resistant layer does not contain an adhesive layer, that is, the sandwich structure erosion-resistant layer consists of a stabilizing layer and a functional layer.

[0147] The corrosion-resistant material weighed 81.87g, and was then placed in a molten aluminum electrolyte and soaked for 20min, 40min, 60min, and 120min, respectively, and then taken out and weighed. The weighed weights were 79.74g, 73.33g, 70.10g, and 58.51g, respectively. After 120min, the weight loss rate of the material was 28.53%.

[0148] Comparative Example 2

[0149] This comparative example is modified as follows based on Example 5:

[0150] The erosion-resistant layer of the sandwich structure does not contain a stabilizing layer, that is, the erosion-resistant layer of the sandwich structure consists of an adhesive layer and a functional layer.

[0151] The corrosion-resistant material weighed 80.34 g and was then placed in a molten aluminum electrolyte and soaked for 20 min, 40 min, 60 min, and 120 min, respectively. The weighed weights were 78.13 g, 75.22 g, 73.64 g, and 63.67 g, respectively. After 120 min, the weight loss rate of the material was 20.75%.

[0152] Comparative Example 3

[0153] This comparative example is modified as follows based on Example 5:

[0154] The erosion-resistant layer of the sandwich structure does not contain a functional layer, that is, the erosion-resistant layer of the sandwich structure consists of an adhesive layer and a stabilizing layer.

[0155] The corrosion-resistant material weighed 81.01 g, and was then placed in a molten aluminum electrolyte and soaked for 20 min, 40 min, 60 min, and 120 min, respectively, before being taken out and weighed. The weighed weights were 78.79 g, 76.90 g, 74.85 g, and 68.22 g, respectively. After 120 min, the weight loss rate of the material was 15.79%.

[0156] The weight loss rates of the corrosion-resistant materials of Examples 1 to 6 and Comparative Examples 1 to 3 after being immersed in molten aluminum for 120 minutes are summarized, and the results are shown in Table 1.

[0157] Table 1 Weight loss rate of corrosion-resistant materials after immersion in molten aluminum for 120 minutes

[0158] Group Weight loss rate, % Example 1 3.97 Example 2 4.08 Example 3 1.06 Example 4 1.48 Example 5 0.59 Example 6 0.75 Comparative Example 1 28.53 Comparative Example 2 20.75 Comparative Example 3 15.79

[0159] It can be seen from Table 1 that the weight loss rate of the corrosion-resistant materials in Examples 1 to 6 after being immersed in molten aluminum for 120 minutes is ≤5%.

[0160] Comparative Example 1 lacks the bonding layer. The lack of the bonding layer (tantalum nitride) causes the stabilization layer (titanium nitride) to be directly bonded to the titanium boride ceramic substrate. The thermal expansion coefficients of the two are significantly different, resulting in strong thermal stress in the high-temperature molten aluminum electrolyte, causing the coating to peel off quickly.

[0161] In comparative example 2, the stabilizing layer is missing. The absence of the stabilizing layer (titanium nitride) causes the bonding layer (tantalum nitride) to be in direct contact with the functional layer (titanium diboride). The difference in thermal expansion coefficients between the two reaches 11%. The thermal stress generated at high temperature exceeds the tensile strength of the coating, forming a penetrating crack.

[0162] Comparative Example 3 lacks the functional layer. The functional layer (titanium diboride) is the first line of defense against molten electrolytes, and its passivation film prevents fluoride ion penetration. This absence directly exposes the stabilizing layer (titanium nitride), increasing the weight loss rate of the corrosion-resistant material.

[0163] In addition, one or more technical solutions in the embodiments of the present application have at least the following technical effects or advantages:

[0164] In the embodiment of the present application, the corrosion-resistant material is not easily corroded by molten aluminum or molten electrolyte. When used in the field of aluminum electrolysis, it can extend the service life of the base material, maintain the integrity and performance stability of the base material, reduce the frequency of maintenance or replacement of the base material, and reduce the cost of material renewal.

[0165] In the embodiments of the present application, the corrosion-resistant material is applied in the field of aluminum electrolysis, which can improve the purity and performance of aluminum products, improve the operating efficiency and production efficiency of aluminum electrolysis, and thus improve the economic benefits of the enterprise.

[0166] In the embodiment of the present application, the corrosion-resistant layer of the sandwich structure can also be applied to other technical fields besides the technical field of aluminum electrolysis, and has broad application prospects.

[0167] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A sandwich structure corrosion-resistant layer for aluminum electrolysis, the sandwich structure corrosion-resistant layer comprising: An adhesive layer covering the surface of the aluminum electrolysis base material, wherein the powder material of the adhesive layer includes one or more of titanium nitride, titanium tungsten, tantalum nitride, graphene, tungsten carbide, and metal nanowires; a stabilizing layer, the stabilizing layer covering the surface of the bonding layer, the powder material of the stabilizing layer comprising: one or more of titanium diboride, titanium nitride, metal nanowires, nickel powder, nickel-based alloy powder, iron powder, and iron-based alloy powder; and A functional layer covers the surface of the stabilizing layer, and the powder material of the functional layer includes one or more of titanium diboride, aluminum oxide, zirconium oxide, graphene, aluminum powder, silicon carbide and tungsten carbide.

2. The erosion-resistant layer of the sandwich structure according to claim 1, characterized in that: The thickness of the adhesive layer is 10 μm to 500 μm.

3. The erosion-resistant layer of the sandwich structure according to claim 1, characterized in that: The thickness of the stabilizing layer is 20 μm to 300 μm.

4. The erosion-resistant layer of the sandwich structure according to claim 1, characterized in that: The thickness of the functional layer is 100 μm to 1600 μm.

5. The erosion-resistant layer of the sandwich structure according to claim 1, characterized in that: The powder material of the bonding layer is spherical or nearly spherical in shape, and has a particle size of 10 μm to 120 μm; The powder material of the stabilization layer is spherical or nearly spherical in shape, and has a particle size of 10 μm to 120 μm; The powder material of the functional layer is spherical or nearly spherical in shape, and has a particle size of 10 μm to 120 μm.

6. A method for preparing the erosion-resistant layer of a sandwich structure according to any one of claims 1 to 5, the method comprising: pre-treating the base material to obtain a pre-treated base material; Screening the powder material of the bonding layer, the powder material of the stabilizing layer and the powder material of the functional layer; The powder material of the bonding layer, the powder material of the stabilization layer and the powder material of the functional layer are sequentially coated on the surface of the pretreated base material to form a sandwich structure corrosion-resistant layer on the surface of the pretreated base material.

7. The erosion-resistant layer of the sandwich structure according to claim 6, characterized in that: The sieving method adopts one or more of air jet screening method, cyclone separator screening method, laser particle size screening method and manual screening method; The coating is carried out by one or more of sputtering deposition, ion plating, pulsed laser deposition, plasma spraying, arc spraying and flame spraying.

8. A corrosion-resistant material for aluminum electrolysis, wherein: Matrix materials for aluminum electrolysis; The sandwich structure erosion-resistant layer according to any one of claims 1 to 5, wherein the sandwich structure erosion-resistant layer covers the surface of the base material, and the bonding layer of the sandwich structure erosion-resistant layer is arranged adjacent to the base material.

9. The erosion-resistant layer of the sandwich structure according to claim 8, characterized in that: The matrix material includes one or more of carbon materials, metal materials, alloy materials, ceramic materials and metal-ceramic composite materials.

10. The erosion-resistant layer of the sandwich structure according to claim 8, characterized in that: The weight loss rate of the corrosion-resistant material after being immersed in molten aluminum liquid for 120 minutes is ≤5%.

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