A high-activity aluminum-based sacrificial anode and its preparation method and application

Abstract

The present invention relates to the field of marine engineering and energy equipment corrosion control, and discloses a high-activity aluminum-based sacrificial anode and its preparation method and application. The mass percentages of the components of the high-activity aluminum-based sacrificial anode are: Ga is 0.8%-2.0%, In is 0.5%-1.2%, Zn is 0.8%-1.2%, Sn is 0.5%-1.2%, and Al is the balance. During preparation, Al ingots, Zn ingots, Sn ingots and Ga-In intermediate alloy ingots are placed in the crucible of a vacuum induction furnace in sequence; smelting begins under argon protection, and gradually heats to 700-720°C; the smelting liquid is cast into a mold and cooled. The high-activity aluminum-based sacrificial anode of the present invention solves the problem of the performance incompatibility of conventional seawater sacrificial anodes in low-salinity seawater environments, has strong electrochemical activity, high capacitance and current efficiency, dissolves evenly, has no harmful components, is suitable for the electrochemical protection of steel facilities in low-salinity seawater environments such as tidal flats and estuaries, and achieves the purpose of corrosion control.

Description

Technical Field

[0001] The invention relates to the field of marine engineering and energy equipment corrosion control, and in particular to a high-activity aluminum-based sacrificial anode and a preparation method and application thereof. Background Art

[0002] The ocean occupies about 70% of the earth's total area, with vast space and rich resources. Therefore, the development and utilization of marine resources are of great significance to the country. Seawater is the most abundant and corrosive natural medium in nature; seawater corrosion has a serious impact on the service performance and service life of marine engineering equipment and structures. Sacrificial anode cathodic protection technology has the characteristics of economic energy saving, simple equipment, and maintenance-free, so it is widely used in cathodic protection of marine engineering structures. This is the most important anti-corrosion technology for the underwater part of the platform. However, with the need for human development of marine resources, more and more corrosion problems in special working conditions need to be solved, which in turn derives an urgent need to develop sacrificial anode materials for different special working conditions.

[0003] my country's coastline, such as the Yangtze River Delta and the Pearl River Delta, the Yellow River estuary, and other river estuaries, are all typical freshwater environments. Rivers or streams flow into the ocean, forming a mixed area of ​​freshwater and seawater. Due to the injection of fresh water, the salinity of seawater decreases and the resistivity of seawater increases. The corrosion environment of oil platforms located at the junction of rivers and seas is typical low-salinity seawater, but the anodes used on their platforms are designed for normal salinity seawater. Due to the low chloride ion concentration and unpredictable salt changes in seawater, the activity of the sacrificial anode is insufficient, the current efficiency is reduced, and the service life of the anode is shortened. Not only does it cause the cathode material to be "underprotected", it also increases the risk of corrosion damage to the platform. If appropriate measures are not taken, it will cause a continuous waste of resources. Therefore, how to effectively ensure the cathodic protection effect of sacrificial anodes for marine engineering equipment in the low-salinity environment of the tidal flat has become an engineering problem that needs to be solved urgently.

[0004] There are many types of commonly used sacrificial anodes, such as zinc-based alloys, magnesium-based alloys, and aluminum-based alloys. At present, different anode materials such as Al-Zn-In, Al-Zn-In-Si, Al-Zn-Cd, and Al-Zn-Mg are mainly used in the corrosion protection of marine engineering structures. These sacrificial anodes have high electrochemical performance in conventional seawater corrosion environments, but in freshwater environments, their anode current efficiency decreases significantly and the surface dissolution is uneven. Therefore, the application of general zinc alloy and aluminum alloy sacrificial anodes in low-salinity seawater environments is limited, and the decrease in conductivity leads to a significant decrease in the activity of the sacrificial anode. The protective effect of the sacrificial anode depends on the selection of sacrificial anode materials and alloying design, so how to select a new type of high-efficiency sacrificial anode for low-salinity seawater environments and make it have a good corrosion control effect on oil platforms is a technical problem that needs to be solved urgently.

[0005] In the existing patents on sacrificial anodes, effective corrosion protection is generally provided for deep-sea engineering equipment. For example, the invention patent with application number 202011203327.0 and publication number CN112323071A, "A kind of aluminum-based sacrificial anode designed with carbide active sites": heat industrial pure aluminum to a molten state; protect the molten industrial pure aluminum melt with argon gas; spray carbon powder into the molten aluminum melt, and control the carbon powder content in the range of 0.1wt%-1wt%; spray the carbon powder into the industrial pure aluminum melt along with argon gas and keep it warm for 1 hour , allowing the carbon powder to fully react with the aluminum melt under the condition of argon stirring: 4Al+3C→AlC, reducing the vacuum degree to atmospheric pressure and cooling to 700°C, then adding the alloy block until it is completely melted and keeping it warm for 5 minutes; stirring the aluminum-based anode alloy material melt with argon to fully mix the alloy components; casting the new active aluminum-based anode material to complete the preparation of the material; the present invention effectively improves the uniform active dissolution performance of the anode material, thereby providing effective corrosion protection for steel oil pipes, casings and deep-sea and polar marine engineering equipment serving in high-temperature and high-pressure environments. Another example is the invention patent "Double-layer aluminum alloy composite sacrificial anode" with application number CN200610045992.5 and publication number CN101033552A, which is composed of two different aluminum-based sacrificial anode materials, the outer aluminum alloy anode has the following components by weight percentage: zinc 2.5-3.5%, gallium 0.05-0.20%, indium 0.01-0.05%, tin 0.01-0.03%, bismuth 0.005-0.05%, and the balance is aluminum; the inner aluminum alloy anode has the following components: zinc 2.5-7.0%, indium 0.018-0.05%, cadmium 0-0.02%, tin 0-0. 075%, magnesium 0-1.5%, silicon 0-0.15%, titanium 0-0.08%, and the balance is aluminum; the present invention makes full use of the advantages of the two aluminum anodes: in the initial protection stage, the outer aluminum anode is used to provide a larger protection current, so that the steel structure is rapidly polarized and a surface deposition layer is quickly generated, so that the current density required to maintain stable polarization is greatly reduced; after the outer layer is consumed, the inner aluminum anode can protect the steel structure at a smaller protection current, giving full play to the characteristics of the inner anode with high current efficiency and long service life. Therefore, it has the advantages of good protection effect, long service life, saving anode materials, etc., and is particularly suitable for the anti-corrosion protection of large-scale steel structure facilities in the ocean. Summary of the invention

[0006] In order to overcome the defects of the prior art, the present invention provides a high-activity aluminum-based sacrificial anode and a preparation method and application thereof.

[0007] A highly active aluminum-based sacrificial anode, which is composed of an aluminum-based component and an alloy element component of Ga, In, Zn, and Sn with activation effects;

[0008] The mass percentages of the various components are: Ga is 0.8%-2.0%, In is 0.5%-1.2%, Zn is 0.8%-1.2%, Sn is 0.5%-1.2%, and Al is the balance.

[0009] The above technical solution can be further optimized as follows:

[0010] The mass percentages of the various components are: Ga is 0.8%, In is 1.2%, Zn is 1.0%, Sn is 1.2%, and Al is the balance.

[0011] The mass percentages of the various components are: Ga is 1.5%, In is 0.9%, Zn is 1.2%, Sn is 0.9%, and Al is the balance.

[0012] The mass percentages of the various components are: Ga is 2.0%, In is 0.5%, Zn is 0.8%, Sn is 0.5%, and Al is the balance.

[0013] Ga and In components adopt Ga-In intermediate alloy ingots to refine their grains and improve their solubility.

[0014] The Zn component uses a Zn ingot, the Sn component uses a Sn ingot, and the Al component uses an Al ingot.

[0015] A method for preparing the above-mentioned high-activity aluminum-based sacrificial anode comprises the following steps:

[0016] (1) Preparation of materials

[0017] According to the mass percentage of each component in the formula of high-activity aluminum-based sacrificial anode, Al ingots, Zn ingots, Sn ingots and Ga-In intermediate alloy ingots are prepared.

[0018] (2) Unloading

[0019] An Al ingot, a Zn ingot, a Sn ingot and a Ga-In master alloy ingot are sequentially placed into a crucible of a vacuum induction furnace.

[0020] (3) Melting

[0021] The metal ingots of the above components are gradually heated to 700-720°C and fully stirred in the electromagnetic environment of a vacuum induction furnace.

[0022] (4) Casting

[0023] The molten metal of each component ingot is poured into a mold.

[0024] (5) Cooling

[0025] The casting in the mold becomes an Al-Ga-In-Zn-Sn sacrificial anode after cooling.

[0026] The above technical solution can be further optimized as follows:

[0027] After washing the furnace several times with argon, smelting begins under argon protection to precisely control its composition and meet the requirements of maintaining high activity in a low-salinity seawater environment.

[0028] An application of the above-mentioned high-activity aluminum-based sacrificial anode, the high-activity aluminum-based sacrificial anode is used for corrosion protection of marine platform facilities at river estuaries, and realizes effective electrochemical protection in low-salinity seawater on tidal flats.

[0029] The actual capacity of the highly active aluminum-based sacrificial anode is greater than 2000A·h / kg, the working potential of the sacrificial anode relative to the saturated calomel electrode is lower than -1200mV, and the current efficiency reaches 80%.

[0030] Compared with the prior art, the present invention has the following significant advantages:

[0031] 1. The high-activity aluminum-based sacrificial anode provided by the present invention has excellent performance in a low-salinity seawater environment, solving the problem that conventional seawater sacrificial anodes are not adaptable to this environment, maintaining high electrochemical activity, having high capacitance and current efficiency, dissolving evenly, and having no harmful components. It is suitable for electrochemical protection of steel facilities in low-salinity seawater environments such as tidal flats and estuaries, achieving the purpose of corrosion control.

[0032] 2. The highly active aluminum-based sacrificial anode has a sufficiently negative stable potential and a sufficiently large open circuit potential difference with the protected metal to achieve complete cathodic protection.

[0033] 3. The theoretical capacity of the highly active aluminum-based sacrificial anode material is large, exceeding 2200 A•h / kg, which makes the anode have a longer service life and good economy under the same protection effect.

[0034] 4. The self-corrosion rate (self-dissolution amount) of the highly active aluminum-based sacrificial anode is small during operation, and the current efficiency reaches 80%, which ensures the cathodic protection effect and economy. The current generated by the dissolution can be efficiently applied to the protected structure.

[0035] 5. The corrosion products produced by the high-activity aluminum-based sacrificial anode during operation are non-toxic and harmless and do not pollute the environment. When the high-activity aluminum-based sacrificial anode is used on marine structures such as ships, offshore platforms, docks, and buried pipelines or other buried metal structures, it will enter the environment in the form of corrosion products after dissolution, and will not pose a threat to the natural environment and the production and life of human society.

[0036] 6. The preparation method of high-activity aluminum-based sacrificial anode is simple, accurate, efficient and reliable in quality.

[0037] 7. It has good promotion prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The working potential of the highly active aluminum-based sacrificial anode changes with time in natural seawater diluted 1, 2, 4, and 8 times;

[0039] Figure 2 The current efficiency of the high-activity aluminum-based sacrificial anode in natural seawater diluted 1, 2, 4, and 8 times;

[0040] Figure 3 It is the capacitance of high-activity aluminum-based sacrificial anode in natural seawater diluted 1, 2, 4, and 8 times. DETAILED DESCRIPTION

[0041] The present invention is described in detail below in conjunction with the embodiments and drawings. Example 1

[0042] A highly active aluminum-based sacrificial anode, which is composed of an aluminum-based component and an alloy element component of Ga, In, Zn, and Sn with activation effects;

[0043] The mass percentages of the various components are: Ga is 0.8%, In is 1.2%, Zn is 1.0%, Sn is 1.2%, and Al is the balance;

[0044] Ga and In components use Ga-In master alloy ingots to refine their grains and improve their solubility;

[0045] The Zn component uses a Zn ingot, the Sn component uses a Sn ingot, and the Al component uses an Al ingot.

[0046] The preparation method thereof comprises the following steps:

[0047] (1) Preparation of materials

[0048] According to the mass percentage of each component in the formula of high-activity aluminum-based sacrificial anode, Al ingots, Zn ingots, Sn ingots and Ga-In intermediate alloy ingots are prepared.

[0049] (2) Unloading

[0050] An Al ingot, a Zn ingot, a Sn ingot and a Ga-In master alloy ingot are sequentially placed into a crucible of a vacuum induction furnace.

[0051] (3) Melting

[0052] After washing the furnace with argon several times, smelting begins under argon protection to precisely control the composition and meet the requirements of maintaining high activity in a low-salinity seawater environment;

[0053] The metal ingots of the above components are gradually heated to 700°C and fully stirred in an electromagnetic environment in a vacuum induction furnace.

[0054] (4) Casting

[0055] The molten metal of each component ingot is poured into a mold.

[0056] (5) Cooling

[0057] The casting in the mold becomes an Al-Ga-In-Zn-Sn sacrificial anode after cooling.

[0058] The electrochemical performance of the high-activity aluminum-based sacrificial anode obtained in Example 1 was tested according to the standard test method specified in GB / T17848-1999. Its open circuit potential was -1.42 V (relative to a saturated calomel electrode) in seawater, its working potential was -1.28 V (relative to a saturated calomel electrode), its capacitance was 2408 A▪h / Kg, and its corrosion and dissolution morphology was relatively uniform, meeting the performance requirements of sacrificial anodes in seawater environments. Example 2

[0059] A highly active aluminum-based sacrificial anode, which is composed of an aluminum-based component and an alloy element component of Ga, In, Zn, and Sn with activation effects;

[0060] The mass percentages of the various components are: Ga is 1.5%, In is 0.9%, Zn is 1.2%, Sn is 0.9%, and Al is the balance;

[0061] Ga and In components use Ga-In master alloy ingots to refine their grains and improve their solubility;

[0062] The Zn component uses a Zn ingot, the Sn component uses a Sn ingot, and the Al component uses an Al ingot.

[0063] The preparation method thereof comprises the following steps:

[0064] (1) Preparation of materials

[0065] According to the mass percentage of each component in the formula of high-activity aluminum-based sacrificial anode, Al ingots, Zn ingots, Sn ingots and Ga-In intermediate alloy ingots are prepared.

[0066] (2) Discharging

[0067] An Al ingot, a Zn ingot, a Sn ingot and a Ga-In master alloy ingot are sequentially placed into a crucible of a vacuum induction furnace.

[0068] (3) Melting

[0069] After washing the furnace with argon several times, smelting begins under argon protection to precisely control the composition and meet the requirements of maintaining high activity in a low-salinity seawater environment;

[0070] The metal ingots of the above components are gradually heated to 710°C and fully stirred in an electromagnetic environment in a vacuum induction furnace.

[0071] (4) Casting

[0072] The molten metal of each component ingot is poured into a mold.

[0073] (5) Cooling

[0074] The casting in the mold becomes an Al-Ga-In-Zn-Sn sacrificial anode after cooling.

[0075] The electrochemical performance of the high-activity aluminum-based sacrificial anode obtained in Example 2 was tested according to the standard test method specified in GB / T17848-1999. In seawater diluted 1 times with distilled water, its open circuit potential was -1.403 V (relative to a saturated calomel electrode), the working potential was -1.228 V (relative to a saturated calomel electrode), the capacitance was 2248 A ▪ h / Kg, the current efficiency was 85.2%, and the dissolution morphology was relatively uniform, with some local unevenness. Example 3

[0076] A highly active aluminum-based sacrificial anode, which is composed of an aluminum-based component and an alloy element component of Ga, In, Zn, and Sn with activation effects;

[0077] The mass percentages of the various components are: Ga is 2.0%, In is 0.5%, Zn is 0.8%, Sn is 0.5%, and Al is the balance;

[0078] Ga and In components use Ga-In master alloy ingots to refine their grains and improve their solubility;

[0079] The Zn component uses a Zn ingot, the Sn component uses a Sn ingot, and the Al component uses an Al ingot.

[0080] The preparation method thereof comprises the following steps:

[0081] (1) Preparation of materials

[0082] According to the mass percentage of each component in the formula of high-activity aluminum-based sacrificial anode, Al ingots, Zn ingots, Sn ingots and Ga-In intermediate alloy ingots are prepared.

[0083] (2) Unloading

[0084] An Al ingot, a Zn ingot, a Sn ingot and a Ga-In master alloy ingot are sequentially placed into a crucible of a vacuum induction furnace.

[0085] (3) Melting

[0086] After washing the furnace with argon several times, smelting begins under argon protection to precisely control the composition and meet the requirements of maintaining high activity in a low-salinity seawater environment;

[0087] The metal ingots of the above components are gradually heated to 720°C and fully stirred in an electromagnetic environment in a vacuum induction furnace.

[0088] (4) Casting

[0089] The molten metal of each component ingot is poured into a mold.

[0090] (5) Cooling

[0091] The casting in the mold becomes an Al-Ga-In-Zn-Sn sacrificial anode after cooling.

[0092] The electrochemical performance of the high-activity aluminum-based sacrificial anode obtained in Example 3 was tested in accordance with the standard test method specified in GB / T17848-1999. In seawater diluted 4 times with distilled water, its open circuit potential was -1.48 V (relative to a saturated calomel electrode), its working potential was -1.18 V (relative to a saturated calomel electrode), its capacitance was 2186 A▪h / Kg, and its current efficiency was 83.4%, which met the performance requirements of the sacrificial anode. Example 4

[0093] like Figure 1 As shown, according to the national standard GB / T17848-1999 "Test method for electrochemical performance of sacrificial anodes", a saturated calomel electrode (SCE) reference electrode was used to test the change in working potential of high-activity aluminum-based sacrificial anodes in natural seawater diluted 1, 2, 4, and 8 times over time.

[0094] The results show that the working potential of the highly active aluminum-based sacrificial anode is relatively stable within the 7-day test period; as the seawater salinity decreases, the working potential of the sacrificial anode material gradually shifts positively to about 200 mV; all potentials are between -1.26 V and -1.46 V, meeting the potential requirements of the highly active sacrificial anode. Example 5

[0095] like Figure 2 As shown, according to the national standard GB / T17848-1999 "Test Method for Electrochemical Performance of Sacrificial Anode", the current density on the high-activity aluminum-based sacrificial anode is 1mA / cm 2 The current efficiency of the high-activity aluminum-based sacrificial anode was tested in natural seawater diluted 1 times, 2 times, 4 times, and 8 times, and the results were 83.72%, 79.02%, 80.18%, and 81.97%, respectively.

[0096] The results show that the current efficiency of the high-activity aluminum-based sacrificial anode in natural seawater diluted 1, 2, 4, and 8 times is 81.22% on average, providing a strong guarantee for achieving a good cathodic protection effect. Example 6

[0097] like Figure 3 As shown, according to the national standard GB / T17848-1999 "Test Method for Electrochemical Performance of Sacrificial Anode", the current density on the high-activity aluminum-based sacrificial anode is 1mA / cm 2 The capacitance of high-activity aluminum-based sacrificial anode in natural seawater diluted 1, 2, 4 and 8 times was tested, and the results were 2393.7A·h / kg, 2259.3A·h / kg, 2292.4A·h / kg and 2368.0A·h / kg respectively.

[0098] The results show that the capacitance of the high-activity aluminum-based sacrificial anode in natural seawater diluted 1, 2, 4, and 8 times is greater than 2200A·h / kg, ensuring that the anode has a long service life and good economy under the same protection effect.

Claims

1. Application of a highly active aluminum-based sacrificial anode, characterized in that: The high-activity aluminum-based sacrificial anode is composed of an aluminum-based component and Ga, In, Zn, and Sn alloy elements with activation effects; the mass percentages of each component are: Ga is 0.8%-2.0%, In is 0.5%-1.2%, Zn is 0.8%-1.2%, Sn is 0.5%-1.2%, and Al is the balance; the high-activity aluminum-based sacrificial anode is used in the field of marine engineering and energy equipment corrosion control; the high-activity aluminum-based sacrificial anode solves the performance incompatibility problem of conventional seawater sacrificial anodes in low-salinity seawater environments, has strong electrochemical activity, high capacitance and current efficiency, uniform dissolution, and no harmful components, and is suitable for corrosion protection of steel facilities including offshore platforms in low-salinity seawater environments in tidal flats, estuaries, and river estuaries, and realizes effective electrochemical protection in low-salinity seawater on tidal flats; The actual capacity of the highly active aluminum-based sacrificial anode is greater than 2000A·h / kg, the working potential of the sacrificial anode relative to the saturated calomel electrode is lower than -1200mV, and the current efficiency reaches 80%.

2. The use of a highly active aluminum-based sacrificial anode according to claim 1, characterized in that: The mass percentages of the components of the high-activity aluminum-based sacrificial anode are: Ga is 0.8%, In is 1.2%, Zn is 1.0%, Sn is 1.2%, and Al is the balance.

3. The use of a highly active aluminum-based sacrificial anode according to claim 1, characterized in that: The mass percentages of the components of the high-activity aluminum-based sacrificial anode are: Ga is 1.5%, In is 0.9%, Zn is 1.2%, Sn is 0.9%, and Al is the balance.

4. The use of a highly active aluminum-based sacrificial anode according to claim 1, characterized in that: The mass percentages of the components of the high-activity aluminum-based sacrificial anode are: Ga is 2.0%, In is 0.5%, Zn is 0.8%, Sn is 0.5%, and Al is the balance.

5. A method for preparing a high-activity aluminum-based sacrificial anode according to claim 1, comprising the following steps: (1) Material preparation: Prepare the materials according to the mass percentage of each component in the formula of high-activity aluminum-based sacrificial anode; Zn ingots are used for Zn components, Sn ingots are used for Sn components, and Al ingots are used for Al components; Ga and In components use Ga-In master alloy ingots to refine their grains and improve their solubility performance; (2) Discharging: placing Al ingot, Zn ingot, Sn ingot and Ga-In master alloy ingot into the crucible of the vacuum induction furnace in sequence; (3) Melting: After washing the furnace with argon gas several times, smelting begins under argon protection to accurately control the composition and meet the requirements of maintaining high activity in a low-salinity seawater environment; gradually heat the metal ingots of the above components to 700-720°C and fully stir them in the electromagnetic environment of a vacuum induction furnace; (4) Casting: pouring the molten metal ingots of each component into a mold; (5) Cooling: After the casting in the mold is cooled, it becomes the Al-Ga-In-Zn-Sn sacrificial anode.

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