Sacrificial anode for dry-wet alternation and high-temperature environment as well as preparation method and application of sacrificial anode

Abstract

The invention relates to the technical field of corrosion prevention of marine equipment, in particular to a sacrificial anode for a dry-wet alternating and high-temperature environment and a preparation method and application of the sacrificial anode. According to the sacrificial anode, the composite material composed of the carbon nanotubes and the metal elements is added into the aluminum-based alloy, the microstructure of the aluminum alloy is improved due to the addition of the carbon nanotubes, the thermal stability of the anode is improved, surface activation of the anode is promoted, the phenomenon that the surface of the anode is crusting and even passivated due to the influence of high temperature and a dry-wet alternating environment is prevented, and the service life of the anode is prolonged. Meanwhile, good conductivity is maintained; and by optimizing the ratio of the carbon nanotubes to the metal elements, the anti-corrosion protection efficiency on a metal structure in a high-temperature and dry-wet alternating environment is enhanced. Therefore, the method is expected to be applied to ocean environments such as ocean crude oil ship ballast tanks, FPSO (Floating Production Storage and Offloading) ballast tanks and mobile oil production platforms. The preparation method provided by the invention is simple and convenient, has a good industrial application prospect, and can improve the production efficiency and reduce the environmental pollution.

Description

Technical Field

[0001] This invention relates to the field of marine equipment corrosion protection technology, and in particular to sacrificial anodes for use in alternating wet and dry and high-temperature environments, their preparation methods and applications. Background Technology

[0002] Sacrificial anode protection technology is widely used in the protection of metal structures in marine environments such as ships, offshore platforms, underwater equipment, and metal oil tanks due to its lack of external power supply, simple structure, and convenient construction. This technology uses a metal with stronger electrochemical activity than the protected metal (such as magnesium alloys, zinc alloys, and aluminum alloys) as the anode. Under the influence of an electric current, an oxidation reaction occurs, effectively inhibiting metal corrosion. In seawater environments, zinc alloys or aluminum alloys are typically selected as the anode material, providing reliable corrosion protection and extending the service life of offshore equipment and facilities. With continuous technological development, the performance of sacrificial anodes has been optimized, and their application scope has been continuously expanded, providing a more efficient and durable corrosion protection solution for metal structures in the marine field.

[0003] Ballast tanks in floating production storage and offloading (FPSO) units, crude oil ocean-going vessels, and mobile oil production platforms are mostly adjacent to crude oil tanks. These tanks experience high temperatures and, due to factors such as crude oil adhesion, are often in alternating wet and dry environments. Commonly used aluminum-based sacrificial anodes exhibit poor dissolution performance and low current efficiency under these conditions, resulting in rapid positive potential shifts and even anode surface passivation, leading to current interruption and loss of their intended protective function. Therefore, higher temperature environments place more stringent demands on the performance of anodes used for cathodic protection. During use, it is essential to ensure a reasonable driving voltage, reduce the risk of passivation failure, and mitigate the accelerated corrosion of the anode material itself due to temperature increases.

[0004] With the continuous advancement of aluminum electrolysis technology, the industry's requirements for anode materials are increasing, particularly in terms of improving current efficiency, extending service life, and reducing consumption. The relevant patented technologies for sacrificial anodes in the existing technology are as follows: CN117403235A discloses a corrosion-resistant sacrificial anode for ships and its preparation method. The sacrificial anode comprises the following elemental components in the following weight percentages: zinc 6.00-8.00%, tin 0.10%, copper 0.2%, magnesium 0.5%, yttrium 0.3%, neodymium 0.5%, nickel 0.2-0.5%, manganese 0.08-0.18%, silicon 0.1%, impurity content ≤0.10%, and the balance being aluminum.

[0005] CN117210719A discloses a Zn-Al-Sn-Li eutectic alloy sacrificial anode, its preparation method, and its application. Li and Sn elements are added to the Zn-Al sacrificial anode material. Sn and Li can form low-solid-solubility alloys or eutectic alloys with Zn, which simultaneously increases the protection potential of the zinc alloy sacrificial anode. In the Zn-Al-Sn-Li eutectic alloy, the Li content is limited to 0.1-2 wt%, the Sn content to 1-5 wt%, and the Al content to 0.1-0.6 wt%.

[0006] CN116732525A discloses a sacrificial anode for use in alternating wet and dry environments on beaches, coastlines, and the same, and its preparation method. The sacrificial anode uses Al as a matrix and also contains Zn, In, Mg, Ga, Bi, and optionally Sn and Pb metal elements, wherein the mass percentage of each metal element is as follows: Zn: 3.00-4.00%; In: 0.017-0.02%; Mg: 1.00-1.50%; Ga: 0.10-0.15%; Sn: 0-0.12%; Bi: 0.40-0.50%; Pb: 0-0.03%; with the balance being Al.

[0007] As can be seen from the publicly disclosed patent technologies mentioned above, the main research direction for sacrificial anodes in achieving cathodic protection is as follows: by screening suitable activating elements and optimizing the production process, the electrochemical performance of the anode can be improved, its dissolution uniformity can be enhanced, and the stripping effect of corrosion products can be strengthened. Research focuses on the synergistic effects of elements such as Zn, In, Sn, Mg, and Ti, as well as impurity control, to ensure the stability of anode performance. Furthermore, heat treatment methods are used to optimize the anode microstructure, reduce the adverse effects of impurities, and thus improve the current efficiency and service life of aluminum alloy anodes.

[0008] However, in alternating wet and dry environments and high-temperature conditions, existing sacrificial anodes suffer from poor dissolution performance, low current efficiency, and rapid positive shift of operating potential. These issues easily lead to passivation of the anode surface, causing current interruption and ultimately resulting in the loss of their intended corrosion protection function. Therefore, effectively improving the electrochemical performance, corrosion resistance, and mechanical properties of sacrificial anodes under extreme environments, extending their service life, and enhancing their corrosion protection effect on metal structures in high-temperature and alternating wet and dry environments has become a key challenge that engineers in the field of marine equipment corrosion protection urgently need to overcome. Summary of the Invention

[0009] This invention aims to at least solve one of the technical problems existing in the related art. Therefore, the first objective of this invention is to provide a sacrificial anode for use in alternating wet and dry environments and high-temperature environments; the second objective of this invention is to provide a method for preparing a sacrificial anode for use in alternating wet and dry environments and high-temperature environments; and the third objective of this invention is to provide applications of the sacrificial anode for use in alternating wet and dry environments and high-temperature environments.

[0010] To achieve the first objective, the technical solution adopted by this invention is as follows: The sacrificial anode used in alternating wet and dry environments and high-temperature environments has the following composition and mass percentage of each component: Metallic Zn 3.5–5.5%; Metallic Mg 0.5–1.5%; Metallic In 0.02–0.04%; Metal Ga 0.005~0.025%; Carbon nanotubes 0.2–0.5%; Balance of metallic Al.

[0011] In terms of material composition, aluminum is used as the matrix, and the electrochemical performance and corrosion resistance of aluminum-based alloys are optimized by adding multiwalled carbon nanotubes (MWCNTs) and zinc (Zn), magnesium (Mg), indium (In), and gallium (Ga). There are significant synergistic effects among the components.

[0012] First, multi-walled carbon nanotubes, as a reinforcing phase material, can improve the microstructure of aluminum-based alloys. Their large specific surface area and good electrical conductivity help improve the conductivity of the anode and reduce the resistance to electron and ion migration. Furthermore, the addition of multi-walled carbon nanotubes enhances the thermal stability and wear resistance of the anode, preventing premature physical damage at high temperatures and thus extending its service life.

[0013] The introduction of metallic elements, especially zinc, magnesium, indium, and gallium, optimizes the anodic electrochemical reaction. Zinc and magnesium exhibit high electrochemical activity in aluminum-based alloys, effectively improving the sacrificial corrosion efficiency of the anode and reducing its consumption rate. Indium further activates the anode surface, enhancing its dissolution performance and ensuring a continuous and stable output current.

[0014] The proportions of each component are also crucial; a proper ratio can optimize the synergistic effect between elements. By precisely controlling the content of multi-walled carbon nanotubes and metal elements, ideal electrochemical performance and durability can be achieved, while avoiding increased costs and decreased performance due to excessive addition.

[0015] Through the synergistic effect among the components, the sacrificial anode microstructure provided by this invention is improved. Specifically, multi-walled carbon nanotubes effectively fill the microscopic defects in the aluminum alloy, enhancing its corrosion resistance and mechanical strength. The selective distribution of metallic elements and the uniform dispersion of multi-walled carbon nanotubes suppress surface passivation, making it less prone to the formation of dense and difficult-to-remove corrosion products on the anode surface.

[0016] The improved anode durability is a result of the combined effect of the reinforcing effect of multi-walled carbon nanotubes and the synergistic effect of metallic elements. The optimized ratio gives the sacrificial anode a longer service life, lower energy consumption, and the ability to adapt to complex marine environments, thus reducing maintenance costs.

[0017] Preferably, the components and their mass percentages are as follows: Metallic Zn 4.5%; Metallic Mg 1%; Metallic In 0.03%; Metal Ga 0.01%; Carbon nanotubes 0.3%; Balance of metallic Al.

[0018] Preferably, the carbon nanotubes have a particle size ≤20µm, a resistivity of 600~1000µΩ·m, and a specific surface area of ​​250~310m². 2 / g, bulk density is 0.02~0.08g / cm³ 3 .

[0019] Preferably, the alternating wet and dry conditions and high-temperature environment mainly refer to the marine environment with a temperature of 45℃ to 60℃.

[0020] To achieve the second objective, the technical solution adopted by this invention is as follows: A method for preparing a sacrificial anode for alternating wet and dry conditions and high-temperature environments, comprising the following melt preparation steps: S100. Anhydrous ethanol is mixed with metallic Al and carbon nanotubes to obtain a slurry mixture I. S200. Apply a pressure of 40-60 MPa to the slurry mixture I using a pressure device to uniformly disperse the carbon nanotubes into the metal Al, thereby obtaining slurry mixture II. S300. After initial melting of the slurry mixture II, Mg metal is added sequentially for the second stage of smelting, Zn metal is added for the third stage of smelting, and In metal and Ga metal are added for the fourth stage of smelting to obtain a melt.

[0021] During the smelting process, metals Al, Mg, Zn, In, and Ga are added sequentially according to their melting points from highest to lowest. The purpose is to first melt high-melting-point metals such as aluminum and magnesium at high temperatures, thus forming a stable matrix; then, the temperature is gradually lowered, and low-melting-point metals (such as zinc, indium, and gallium) are added to reduce the loss of volatile elements, avoid the formation of harmful phases, and optimize the uniformity of the alloy composition. By controlling the temperature in stages, it is possible to ensure the complete melting of high-melting-point metals while shortening the exposure time of low-melting-point metals to the high-temperature environment, thereby improving smelting efficiency and reducing energy consumption. Carbon nanotubes are preferentially mixed with aluminum, the metal added in the largest quantity, to ensure uniform dispersion.

[0022] Preferably, in step S200, the initial melting temperature is 800–1200℃ and the melting time is 20–30 min; the melting temperature in the second stage is 800–1000℃ and the melting time is 10–20 min; the melting temperature in the third stage is 700–800℃ and the melting time is 20–30 min; and the melting temperature in the fourth stage is 600–700℃ and the melting time is 10–20 min.

[0023] Preferably, in step S200, the initial melting temperature is 1000℃ and the melting time is 25min; the melting temperature in the second stage is 900℃ and the melting time is 15min; the melting temperature in the third stage is 750℃ and the melting time is 25min; and the melting temperature in the fourth stage is 650℃ and the melting time is 15min.

[0024] Preferably, the method further includes the following steps: S400. The melt is poured into a preheated mold to obtain a casting. S500 After the casting solidifies and takes shape, it is cooled and removed to obtain a sacrificial anode for use in alternating wet and dry environments and high-temperature environments.

[0025] Preferably, in step S400, the preheating temperature is 450–550°C.

[0026] To achieve the third objective, the technical solution adopted by this invention is as follows: Applications of sacrificial anodes for wet-dry and high-temperature environments, the applications including using the sacrificial anodes described in any of the above-mentioned sacrificial anodes for wet-dry and high-temperature environments in metal structures of any one or more of the following: ships, offshore platforms, underwater equipment, and metal oil tanks.

[0027] The above-described one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects: The sacrificial anode provided by this invention for use in alternating wet and dry environments and high-temperature conditions significantly optimizes the electrochemical performance and corrosion resistance of the sacrificial anode by using a composite material composed of carbon nanotubes and metallic elements added to an aluminum-based alloy. This effectively extends the anode's service life and enhances its corrosion protection performance for metal structures under high-temperature and alternating wet and dry conditions. Therefore, this sacrificial anode is expected to be applied in sacrificial anode protection systems for metal structures in marine environments such as ballast tanks of ocean-going crude oil vessels, FPSO ballast tanks, and mobile oil production platforms.

[0028] The addition of carbon nanotubes improves the microstructure of aluminum alloys, enhances the thermal stability of the anode, promotes the activation of the anode surface, and prevents the anode surface from crusting or even passivating due to the influence of high temperature and alternating wet and dry environments, while maintaining good electrical conductivity. In addition, the addition of carbon nanotubes further enhances the anode performance, making it exhibit higher efficiency in the electrochemical protection process.

[0029] The present invention provides a method for preparing a sacrificial anode for use in alternating wet and dry environments and high-temperature conditions. During the smelting process, metals Al, Mg, Zn, In, and Ga are added sequentially according to their melting points from highest to lowest. High temperatures are used to melt high-melting-point metals such as aluminum and magnesium, thereby forming a stable matrix. Subsequently, the temperature is gradually decreased, and low-melting-point metals (such as zinc, indium, and gallium) are added to reduce the loss of volatile elements, avoid the formation of harmful phases, and optimize the uniformity of the alloy composition. By controlling the temperature in stages, the high-melting-point metals are ensured to melt completely, while the exposure time of low-melting-point metals to the high-temperature environment is shortened, thus improving smelting efficiency and reducing energy consumption. Carbon nanotubes are preferentially mixed with aluminum, the metal added in the largest quantity, to ensure uniform dispersion.

[0030] The preparation method provided by this invention is simple, has good prospects for industrial application, and can improve production efficiency and reduce environmental pollution.

[0031] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0032] Figure 1 This is a display image of the sacrificial anode product for use in alternating wet and dry environments and high-temperature environments, provided in Embodiment 5 of the present invention.

[0033] Figure 2 This is a surface corrosion and dissolution morphology image of the sacrificial anode product provided in Embodiment 5 of the present invention after electrochemical experiments in alternating wet and dry environments and high temperature environments.

[0034] Figure 3This is a surface corrosion and dissolution morphology image of a sacrificial anode product after cleaning following inspection, provided in Embodiment 5 of the present invention, for use in alternating wet and dry conditions and high-temperature environments. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. The following embodiments are used to illustrate this invention, but cannot be used to limit the scope of this invention.

[0036] In the following embodiments, unless otherwise specified, the experimental methods used are conventional methods, and the materials and reagents used are commercially available, unless otherwise specified, and are carried out in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions.

[0037] The physicochemical properties of the carbon nanotubes used in the following examples are shown in the table below:

[0038] Example 1 Sacrificial anodes are used in alternating wet and dry environments and high-temperature environments. The sacrificial anode is based on Al and also contains metallic Zn, metallic Mg, metallic In, metallic Ga, and carbon nanotubes. The mass percentages of each component are as follows: Zn (3.5%); Mg (0.5%); In (0.02%); Ga (0.005%); Carbon nanotubes (0.2%); Balance: Metallic Al; Among them, the carbon nanotubes have a particle size ≤20µm, a resistivity of 600µΩ·m, and a specific surface area of ​​250m². 2 / g, bulk density 0.02g / cm³ 3 .

[0039] Its preparation process is as follows: S100. Weigh the Al metal raw materials and carbon nanotubes according to the ratio and put them into a dry container. Add a certain amount of anhydrous ethanol and stir continuously to mix the carbon nanotubes with the Al metal raw materials to obtain a uniform slurry mixture I. S200. Place the slurry mixture in a pressure device and apply pressure to the slurry mixture. The pressure is set to 40 MPa to promote closer contact and mixing between carbon nanotubes and Al metal raw materials, so that the carbon nanotubes are uniformly dispersed in the Al metal raw materials to obtain slurry mixture II. S300: Take the slurry-like mixture II and pour it into the crucible of the gold melting furnace for initial melting. Melt it at 800℃ for 30 minutes. Then add metallic Mg and melt it at 800℃ for 20 minutes. After it is completely melted, add metallic Zn and melt it at 700℃ for 30 minutes. Finally, add metallic In and Ga and continue to melt it at 600℃ for 20 minutes to make it a melt. S400. Slowly pour the melt into a mold preheated to 500°C to obtain the casting. S500. After the casting in the mold solidifies and cools, it is removed to obtain a sacrificial anode for use in alternating wet and dry environments and high-temperature environments.

[0040] Example 2 Sacrificial anodes for use in alternating wet and dry environments and high-temperature conditions, with metallic Al as the matrix, also containing metallic Zn, Mg, In, Ga and carbon nanotubes, wherein the mass percentages of each component are as follows: Zn (4.5%); Mg (1%); In (0.03%); Ga (0.01%); Carbon nanotubes (0.3%); Balance Al; The carbon nanotubes have a particle size of ≤20µm, a resistivity of 744.9µΩ·m, and a specific surface area of ​​258.3m². 2 / g, bulk density 0.039g / cm³ 3 .

[0041] Its preparation process is as follows: S100, same as in Example 1; S200, the pressure setting is changed to 50MPa, the rest is the same as in Example 1; S300: Take the slurry mixture II and pour it into the crucible of the gold melting furnace for initial melting. Melt it at 1000℃ for 25 minutes. Then add Mg metal and melt it at 900℃ for 15 minutes. After it is completely melted, add Zn metal and melt it at 750℃ for 25 minutes. Finally, add In and Ga metals and continue to melt it at 650℃ for 15 minutes to make it a melt. S400, same as in Example 1; S500, same as Example 1.

[0042] Example 3 A sacrificial anode for use in alternating wet and dry environments and high-temperature environments, the sacrificial anode being based on Al, characterized in that it further comprises metals Zn, Mg, In, and Ga, wherein the mass percentages of each component are as follows: Zn (5.5%); Mg (1.5%); In (0.04%); Ga (0.025%); Carbon nanotubes (0.5%); Balance Al; Among them, the carbon nanotubes have a particle size ≤20µm, a resistivity of 1000µΩ·m, and a specific surface area of ​​310m². 2 / g, bulk density 0.08g / cm³ 3 .

[0043] Its preparation process is as follows: S100, same as in Example 1; S200, the pressure setting is changed to 60MPa, the rest is the same as in Example 1; S300: Take the slurry-like mixture II and pour it into the crucible of the gold melting furnace for initial melting. Melt it at 1200℃ for 20 minutes. Then add metallic Mg and melt it at 1000℃ for 10 minutes. After it is completely melted, add metallic Zn and melt it at 800℃ for 20 minutes. Finally, add metallic In and Ga and continue to melt it at 700℃ for 10 minutes to make it a melt. S400, same as in Example 1; S500, same as Example 1.

[0044] Example 4 Sacrificial anodes for use in alternating wet and dry environments and high-temperature conditions, with metallic Al as the matrix, also containing metallic Zn, Mg, In, Ga and carbon nanotubes, wherein the mass percentages of each component are as follows: Zn (4.5%); Mg (1%); In (0.03%); Ga (0.01%); Carbon nanotubes (0.2%); Balance Al; The carbon nanotubes have a particle size of 5.943 µm, a resistivity of 744.9 µΩ·m, and a specific surface area of ​​258.3 m². 2 / g, bulk density 0.039g / cm³ 3 .

[0045] The preparation process is the same as in Example 2.

[0046] The electrochemical performance of the obtained Al-Zn-Mg-Ga-In-carbon nanotube aluminum sacrificial anode was tested according to the standard test method specified in GB / T 17848-1999 "Test Method for Electrochemical Performance of Sacrificial Anodes". The test medium was artificial seawater with pH = 8.2, and the experimental temperature was 45℃. An intermittent immersion test was used, with a wet-dry time ratio of 2:1. The sacrificial anode sample was first immersed in artificial seawater for 48 hours. After immersion, the sacrificial anode sample was exposed to saturated humidity air for 24 hours to simulate corrosion behavior under alternating wet-dry and high-temperature conditions. Seven cycles were performed, each lasting 72 hours. A saturated calomel electrode was used as the reference electrode. The results showed that the sacrificial anode surface dissolved uniformly, and the corrosion products were easily detached. Simultaneously, the current efficiency of the sacrificial anode provided in this embodiment was measured to be 80%. Example 5 The composition and mass percentage of each component of the sacrificial anode used in alternating wet and dry and high-temperature environments are the same as in Example 4, except that the carbon nanotube content in Example 4 is replaced with 0.3%. The preparation process is the same as in Example 4, resulting in a sacrificial anode suitable for alternating wet and dry conditions and high-temperature environments, such as... Figure 1 As shown.

[0047] The electrochemical performance testing process was the same as in Example 4, with three samples tested in parallel (referred to as Sample 1, Sample 2, and Sample 3). The test results are as follows: Figure 2 and Figure 3 As shown, the results indicate that the sacrificial anode surface is uniformly dissolved, and the corrosion products are easily detached. Furthermore, the current efficiency of the sacrificial anode provided in this embodiment was measured to be 82%. Example 6 The composition and mass percentage of each component of the sacrificial anode used in alternating wet and dry and high-temperature environments are the same as in Example 4, except that the carbon nanotube content in Example 4 is replaced with 0.4%. The preparation process is the same as in Example 4.

[0048] The electrochemical performance testing process was the same as in Example 4. The results showed that the sacrificial anode surface was uniformly dissolved, and the corrosion products were easily detached. Simultaneously, the current efficiency of the sacrificial anode provided in this example was measured to be 78%.

[0049] Example 7 The composition and mass percentage of each component of the sacrificial anode used in alternating wet and dry and high-temperature environments are the same as in Example 4, except that the carbon nanotube content in Example 4 is replaced with 0.4%. The preparation process is the same as in Example 4.

[0050] The electrochemical performance testing process was the same as in Example 4. The results showed that the sacrificial anode surface was uniformly dissolved, and the corrosion products were easily detached. Simultaneously, the current efficiency of the sacrificial anode provided in this example was measured to be 73%.

[0051] As shown in the current efficiencies measured in Examples 4-7, the current efficiency first increases and then decreases with increasing carbon nanotube content. This is mainly due to the effect and dispersion of carbon nanotubes in the aluminum sacrificial anode. At lower contents (such as in Examples 4 and 5), carbon nanotubes help improve the conductivity of the metal matrix, promote current transport, and increase current efficiency. With increasing content (such as in Examples 6 and 7), uneven dispersion may lead to unstable electrochemical reactions, reduce current efficiency, and affect the shedding of corrosion products and capacitance of the anode.

[0052] Considering current efficiency, capacitance, and corrosion product shedding, Example 5 (0.3% carbon nanotube content) performed best. The sacrificial anodes provided in Examples 4-7 of this invention for use in alternating wet and dry conditions and high-temperature environments exhibit current efficiencies of 73-82% and capacitances of 1547 Ah / kg-1668 Ah / kg, balancing conductivity and electrochemical reactions. Furthermore, the corrosion products are easily shed, improving the anode's lifespan and performance stability.

[0053] Example 8 The sacrificial anode used in wet-dry and high-temperature environments, the composition and mass percentage of each component of the sacrificial anode used in wet-dry and high-temperature environments are the same as in Example 2, except that the content of metallic Ga in Example 2 is replaced with 0.2%. The preparation process is the same as in Example 2.

[0054] The electrochemical performance testing process was the same as in Example 4, and the results showed that the sacrificial anode surface was uniformly dissolved, and the corrosion products were easily detached. Simultaneously, the current efficiency of the sacrificial anode provided in this example was measured to be 69%.

[0055] Experimental results show that increasing the gallium content did not significantly affect the basic electrochemical performance of the anode, and may even result in more stable corrosion behavior during long-term use. Therefore, considering both performance and stability, the optimal gallium content is 0.01%.

[0056] Based on the sacrificial anodes provided in Examples 1 to 8, it can be seen that adding carbon nanotubes and metallic elements (such as zinc, magnesium, gallium, and indium) to the aluminum matrix can effectively improve the electrical conductivity, corrosion resistance, and mechanical strength of the sacrificial anode. Therefore, carbon nanotubes can optimize the structure of aluminum alloys, enhance their thermal stability and wear resistance, and thus reduce anode consumption. In applications such as electrolytic smelting and electrochemical protection, this aluminum anode is expected to exhibit a longer service life, lower energy consumption, and better environmental adaptability. By optimizing the ratio of carbon nanotubes to metallic elements, this invention can improve anode performance while reducing costs. The preparation method provided by this invention is simple, has good industrial application prospects, and can improve production efficiency and reduce environmental pollution.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A sacrificial anode for use in alternating wet and dry environments and high-temperature environments, characterized in that, The composition and the mass percentage of each component are as follows: Metallic Zn 3.5–5.5%; Metallic Mg 0.5–1.5%; Metallic In 0.02–0.04%; Metal Ga 0.005~0.025%; Carbon nanotubes 0.2–0.5%; Balance of metallic Al.

2. The sacrificial anode for use in alternating wet and dry environments and high-temperature environments as described in claim 1, characterized in that, The composition and the mass percentage of each component are as follows: Metallic Zn 4.5%; Metallic Mg 1%; Metallic In 0.03%; Metal Ga 0.01%; Carbon nanotubes 0.3%; Balance of metallic Al.

3. The sacrificial anode for alternating wet and dry conditions and high-temperature environments as described in claim 1, characterized in that, The carbon nanotubes have a particle size ≤20µm, a resistivity of 600~1000µΩ·m, and a specific surface area of ​​250~310m². 2 / g, bulk density is 0.02~0.08g / cm³ 3 .

4. The sacrificial anode for use in alternating wet and dry environments and high-temperature environments as described in claim 1, characterized in that, The alternating wet and dry conditions and high-temperature environment mainly refer to the marine environment, with temperatures ranging from 45°C to 60°C.

5. A method for preparing a sacrificial anode for use in alternating wet and dry environments and high-temperature environments, characterized in that, The preparation of a sacrificial anode for use in alternating wet and dry environments and high-temperature environments as described in any one of claims 1 to 4 comprises the following melt preparation steps: S100. Anhydrous ethanol is mixed with metallic Al and carbon nanotubes to obtain a slurry mixture I. S200. Apply a pressure of 40-60 MPa to the slurry mixture I using a pressure device to uniformly disperse the carbon nanotubes into the metal Al, thereby obtaining slurry mixture II. S300. After initial melting of the slurry mixture II, Mg metal is added sequentially for the second stage of smelting, Zn metal is added for the third stage of smelting, and In metal and Ga metal are added for the fourth stage of smelting to obtain a melt.

6. The method for preparing a sacrificial anode for alternating wet and dry conditions and high-temperature environments as described in claim 5, characterized in that, In step S200, the initial melting temperature is 800–1200℃ and the melting time is 20–30 min; the melting temperature in the second stage is 800–1000℃ and the melting time is 10–20 min; the melting temperature in the third stage is 700–800℃ and the melting time is 20–30 min; and the melting temperature in the fourth stage is 600–700℃ and the melting time is 10–20 min.

7. The method for preparing a sacrificial anode for alternating wet and dry conditions and high-temperature environments as described in claim 6, characterized in that, In step S200, the initial melting temperature is 1000℃ and the melting time is 25 min; the melting temperature in the second stage is 900℃ and the melting time is 15 min; the melting temperature in the third stage is 750℃ and the melting time is 25 min; and the melting temperature in the fourth stage is 650℃ and the melting time is 15 min.

8. The method for preparing a sacrificial anode for alternating wet and dry conditions and high-temperature environments as described in claim 5, characterized in that, It also includes the following steps: S400. The melt is poured into a preheated mold to obtain a casting. S500 After the casting solidifies and takes shape, it is cooled and removed to obtain a sacrificial anode for use in alternating wet and dry environments and high-temperature environments.

9. The method for preparing a sacrificial anode for alternating wet and dry conditions and high-temperature environments as described in claim 8, characterized in that, In step S400, the preheating temperature is 450–550°C.

10. Application of sacrificial anodes in alternating wet and dry environments and high-temperature environments, characterized in that, The application includes using the sacrificial anode as described in any one of claims 1 to 4 for wet-dry and high-temperature environments in metal structures of any one or more of the following: ships, offshore platforms, underwater equipment, and metal oil tanks.

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