A micro magnetic sacrificial anode for corrosion protection of steel sheet piles in tidal range areas

Abstract

The invention relates to the technical field of metal material anti-corrosion and the field of construction engineering, and specifically discloses a micro-magnetic sacrificial anode for corrosion protection in a tidal range area of ​​a steel sheet pile. The anode consists of a three-layer structure, which comprises a strontium ferrite magnetic core, a metal nickel transition layer, and a metal zinc functional layer from the inside to the outside. The preparation method comprises the following steps of degreasing, chemical nickel plating, hot-dip galvanizing, and magnetizing strontium ferrite particles in sequence. The sacrificial anode has the advantages of simple installation, convenient maintenance, and good anti-corrosion effect. It can form effective cathode protection when installed in a tidal range area of ​​a steel sheet pile, and can effectively solve the current problem of local corrosion in the tidal range area of ​​the steel sheet pile.

Description

Technical Field

[0001] The invention relates to the technical field of metal corrosion, in particular to a micro magnetic sacrificial anode used for corrosion protection of steel sheet piles in tidal range areas. Background Art

[0002] The ocean has huge economic benefits and an important national defense status. Ocean-related construction projects have been booming in recent years. Steel sheet piles are widely used in permanent structural buildings (piers, unloading yards, embankment revetments, breakwaters, diversion dikes, docks, gates) and temporary structures (temporary bank expansion, bridge cofferdams) because of their high strength, good water-proofing, strong durability, reusability, and the ability to significantly reduce the construction costs of marine projects and shorten the construction period. The main materials of steel sheet piles include carbon steel and low-alloy steel, which will suffer severe corrosion in seawater media (usually containing ~20,000pp chloride ions). Corrosion protection of steel sheet piles is the key to improving their service life.

[0003] In order to meet the service life requirements of marine structures, heavy-duty anti-corrosion coatings and sacrificial anode cathodic protection are usually used to protect steel sheet piles from corrosion. The coating protection method can effectively inhibit the corrosion of the atmospheric zone and the wave splash zone of the steel sheet piles, and the cathodic protection can effectively solve the corrosion problem of the underwater part and the part below the mud surface of the steel sheet piles. However, both anti-corrosion methods are not effective in protecting the steel sheet piles from corrosion in the tidal range zone. The steel sheet piles are prone to local corrosion in the tidal range zone, causing the structure to fail prematurely. There are three main reasons for local corrosion in the tidal range zone: (1) The chloride ion concentration in the thin liquid film area on the surface of the steel sheet piles in the tidal range zone is high due to the evaporation of seawater; (2) The dissolved oxygen content in the thin liquid film area on the surface of the steel sheet piles in the tidal range zone is high, which accelerates the occurrence of galvanic corrosion reactions; (3) The thin liquid film in the tidal range zone is isolated from the main body of seawater, thus forming a large number of micro-area corrosion primary cells ( Figure 2 The usual sacrificial anode is a large anode weighing tens of kilograms, which is installed below the seawater level and connected to the steel sheet piles through wires. Therefore, it can only protect the part of the steel sheet pile below the liquid level, and cannot form an effective protection circuit for the tidal range area isolated from the main body of seawater ( Figure 2 ).

[0004] Since the main seawater is isolated from the thin liquid film of the steel sheet piles, it is difficult for traditional large sacrificial anodes to effectively protect the steel sheet piles in the tidal range area. Summary of the invention

[0005] The present invention provides a micro-magnetic sacrificial anode for corrosion protection of steel sheet piles in tidal range areas. The anode can be installed in the tidal range area of ​​the steel sheet piles by magnetic attraction, and can form effective cathodic protection for the tidal range area. At the same time, the anode has the characteristics of easy and simple installation, convenient maintenance, low price and easy availability, and excellent anti-corrosion effect.

[0006] To achieve the above-mentioned purpose, the present invention provides the following technical solution: a miniature magnetic sacrificial anode for corrosion protection of steel sheet piles in tidal range areas, characterized in that it consists of a three-layer structure, wherein the inner layer is a strontium ferrite magnetic core, the middle layer is a metal nickel transition layer, and the outer layer is a metal zinc functional layer.

[0007] Preferably, the strontium ferrite magnetic core size is 100 μm-5000 μm, the metal nickel transition layer thickness is 1 μm-10 μm, and the metal zinc functional layer thickness is 100 μm-6000 μm. Preferably, the strontium ferrite composition is SrFe12O19.

[0008] Preferably, the metal zinc layer consists of Zn, Al, Cd, Fe, Pb and Cu, wherein the mass fraction of Zn is 99.0%-99.7%.

[0009] Preferably, the zinc bath temperature of the hot-dip galvanizing is 440°C-460°C.

[0010] The preparation process of the above-mentioned micro-magnetic sacrificial anode for corrosion protection of steel sheet piles in tidal range areas is as follows: first, the strontium ferrite particles are degreased and cleaned with clean water, and then a layer of metal nickel is plated on the surface of the strontium ferrite particles by chemical plating, and a layer of metal zinc is plated on the surface of the metal iron by hot-dip galvanizing, and finally the strontium ferrite magnet particles are magnetized.

[0011] The present invention has the following characteristics and beneficial effects:

[0012] The micro magnetic sacrificial anode provided by the present invention is installed in the tidal range area of ​​the steel sheet pile, which can form effective cathodic protection for the tidal range area and effectively solve the current local corrosion problem of the steel sheet pile in the tidal range area.

[0013] The micro-magnetic sacrificial anode provided by the present invention can be fixed on the steel sheet pile by magnetic attraction, and the installation method is simple and convenient for subsequent maintenance;

[0014] The micro-magnetic sacrificial anode provided by the present invention is dispersedly installed in the tidal range area of ​​the steel sheet pile, which can make the cathode protection current distribution more uniform and have a better anti-corrosion effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the structure of a micro-magnetic sacrificial anode of the present invention;

[0016] Figure 2 This is the working principle diagram of the traditional sacrificial anode;

[0017] Figure 3 This is a working principle diagram of the micro-magnetic sacrificial anode of the present invention;

[0018] In the figure: 1. Strontium ferrite magnetic core; 2. Metal nickel transition layer; 3. Metal zinc functional layer; 4. Tidal range zone; 5. Underwater zone; 6. Thin liquid film; 7. Anode; 8. Micro magnetic anode; 9. Steel sheet pile. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present invention.

[0020] In the description of the embodiments of the present invention, it should be understood that the terms "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present invention.

[0021] The present invention proposes a miniature sacrificial anode, which is composed of relatively small zinc alloy particles (0.1-10 mm). The sacrificial anode is dispersedly installed in the tidal range area of ​​the steel sheet pile. The lower part of the tidal range area of ​​the steel sheet pile is an underwater area, which can ensure that there is a sacrificial anode in each isolation thin liquid film in the tidal range area, thereby forming effective cathodic protection for the tidal range area of ​​the steel sheet pile, thereby solving the local corrosion problem of the steel sheet pile in this area. However, since the miniature sacrificial anode is relatively small and there are a large number of them, the usual wire connection is too cumbersome. Adding a magnetic core inside the sacrificial anode can make it magnetic, and it can be fixed and installed by simple magnetic attraction. Among magnetic materials, strontium ferrite has the advantages of high coercivity Hc and high magnetic energy product (BH) m, and is cheap and easy to obtain, and is an ideal miniature sacrificial anode magnetic core. However, the iron oxide in the strontium iron oxide can react chemically with the outer metal zinc, thereby destroying the structure of the sacrificial anode. Metal nickel does not react chemically with strontium ferrite or zinc metal, and is an ideal intermediate transition layer. By preparing a nickel metal transition layer between strontium ferrite and zinc metal by chemical plating, the stability of the micro magnetic anode can be significantly improved.

[0022] Example 1

[0023] In this case, SrFe12O19 strontium ferrite was used as the core, and a micro-magnetic sacrificial anode was prepared through degreasing, chemical nickel plating, hot-dip galvanizing (450oC), and magnetization processes. The core size of the strontium ferrite was 500μm, the thickness of the metal nickel transition layer was 5μm, and the thickness of the metal zinc (Zn mass fraction>99.7%) layer was 1000μm. The micro-magnetic sacrificial anode was dispersedly installed in the tidal range area of ​​a certain wharf steel sheet pile (Mariner type steel sheet pile produced by Nippon Steel Corporation, and the steel sheet pile under the water surface was normally installed with a traditional sacrificial anode) by magnetic adsorption. After 2 years of service experiments, the tidal range area of ​​the steel sheet pile was cleaned and the corrosion was measured. The measurement results showed that no obvious corrosion pits were found in the tidal range area of ​​the steel sheet pile using the micro-magnetic sacrificial anode, and local corrosion was resolved.

[0024] Comparative Example 1

[0025] In this case, only traditional sacrificial anodes were installed on steel sheet piles (Mariner steel sheet piles produced by Nippon Steel Corporation) at a certain dock. After two years of service experiment, the tidal range area of ​​the steel sheet piles was cleaned and the corrosion situation was measured. The measurement results showed that a large number of corrosion pits appeared in the tidal range area of ​​the steel sheet piles, and the local corrosion phenomenon was relatively serious.

[0026] Example 2

[0027] In this case, SrFe12O19 strontium ferrite was used as the core. A micro-magnetic sacrificial anode was prepared through degreasing, chemical nickel plating, hot-dip galvanizing (440oC), and magnetization processes. The core size of the strontium ferrite was 100μm, the thickness of the metal nickel transition layer was 1μm, and the thickness of the metal zinc (the mass fractions of Zn, Al, Cd, Fe, Pb, and Cu were 99.5%, 0.4%, 0.05%, 0.005%, 0.005%, and 0.005%, respectively) layer was 1000μm. The micro-magnetic sacrificial anode was dispersedly installed in the tidal range area of ​​a certain wharf steel sheet pile (Q235B carbon steel, the steel sheet pile under the water surface was normally installed with a traditional sacrificial anode) by magnetic adsorption. After 3 years of service experiments, the tidal range area of ​​the steel sheet pile was cleaned and the corrosion was measured. The measurement results showed that no obvious corrosion pits were found in the tidal range area of ​​the steel sheet pile using the micro-magnetic sacrificial anode, and local corrosion was solved.

[0028] Comparative Example 2

[0029] In this case, only traditional sacrificial anodes were installed on steel sheet piles (Q235B carbon steel) at a certain dock. After three years of service experiment, the tidal range area of ​​the steel sheet piles was cleaned and the corrosion situation was measured. The measurement results showed that a large number of corrosion pits appeared in the tidal range area of ​​the steel sheet piles, and the depth of the deeper corrosion pits could reach 4mm, and the local corrosion phenomenon was relatively serious.

[0030] Example 3

[0031] In this case, SrFe12O19 strontium ferrite was used as the core. A micro-magnetic sacrificial anode was prepared through degreasing, chemical nickel plating, hot-dip galvanizing (460oC), and magnetization processes. The core size of the strontium ferrite was 4000μm, the thickness of the metal nickel transition layer was 5μm, and the thickness of the metal zinc (the mass fractions of Zn, Al, Cd, Fe, Pb, and Cu were 99.7%, 0.2%, 0.02%, 0.005%, 0.005%, and 0.005%, respectively) layer was 5000μm. The micro-magnetic sacrificial anode was dispersedly installed in the tidal range area of ​​a steel sheet pile (Q345B carbon steel, and the part under the water surface of the steel sheet pile was normally installed with a traditional sacrificial anode) at a certain wharf by magnetic adsorption. After 3 years of service experiments, the tidal range area of ​​the steel sheet pile was cleaned and the corrosion was measured. The measurement results showed that no obvious corrosion pits were found in the tidal range area of ​​the steel sheet pile using the micro-magnetic sacrificial anode, and local corrosion was solved.

[0032] Comparative Example 3

[0033] In this case, only traditional sacrificial anodes were installed on steel sheet piles (Q345B carbon steel) at a certain dock. After three years of service experiment, the tidal range area of ​​the steel sheet piles was cleaned and the corrosion situation was measured. The measurement results showed that a large number of corrosion pits appeared in the tidal range area of ​​the steel sheet piles, and the depth of the deeper corrosion pits could reach 6mm, and the local corrosion phenomenon was relatively serious.

[0034] In the description of the present invention, the terms "first", "second", "another", and "yet another" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of the embodiments of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0035] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. In addition, in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0036] While embodiments of the present invention have been shown and described, those skilled in the art will appreciate that numerous changes, modifications, substitutions and variations may be made to the embodiments without departing from the spirit and scope of the present invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A micro magnetic sacrificial anode for corrosion protection of steel sheet piles in tidal range areas, characterized by: The anode is composed of a three-layer structure, in which the inner layer is a strontium ferrite magnetic core, the middle layer is a metal nickel transition layer, and the outer layer is a metal zinc functional layer; its preparation process is as follows: S1: Degreasing the strontium ferrite particles and washing them with clean water; S2: Plating a layer of metal nickel on the surface of strontium iron oxide particles by chemical plating; S3: Plating a layer of metal zinc on the surface of the metal nickel by hot-dip galvanizing; S4: magnetizing the strontium ferrite magnet particles that have completed the steps S1, S2, and S3; The anodes are dispersedly installed in the tidal range area of ​​the steel sheet piles. The lower part of the tidal range area of ​​the steel sheet piles is the underwater area, ensuring that there is a sacrificial anode in each isolation thin liquid film in the tidal range area, thereby forming effective cathodic protection for the tidal range area of ​​the steel sheet piles, thereby solving the local corrosion problem in the tidal range area of ​​the steel sheet piles; The strontium ferrite magnetic core has a size of 100 μm-5000 μm, the metal nickel transition layer has a thickness of 1 μm-10 μm, and the metal zinc functional layer has a thickness of 100 μm-6000 μm; The strontium ferrite component is SrFe 12 O 19 ; The hot-dip galvanizing bath temperature range is 440 o C-460 o C.

2. A micro magnetic sacrificial anode for corrosion protection of steel sheet piles in tidal range areas according to claim 1, characterized in that: The chemical plating times are 1-10 times, and the hot-dip galvanizing times are 1-60 times.

3. The micro magnetic sacrificial anode for corrosion protection of steel sheet piles in tidal range areas according to claim 1, characterized in that: The metal zinc functional layer consists of Zn, Al, Cd, Fe, Pb and Cu, wherein the mass fraction of Zn is 99.0%-99.7%.

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