Sacrificial anode device, application thereof and raw material composition for gel-based composite material

Abstract

The invention relates to the technical field of metal corrosion and protection, in particular to a sacrificial anode device, application of the sacrificial anode device and a raw material composition for a gel-based composite material. The sacrificial anode device comprises a metal sacrificial anode and a gelling-based composite material wrapping the metal sacrificial anode, and the gelling-based composite material is of a porous structure with the micro-nano size. The sacrificial anode device is stable in current output and high in dechlorination efficiency, the risk of corrosion product expansion can be reduced, volume expansion of corrosion products can be effectively relieved, and long-term stable protection of metal can be achieved.

Description

Technical Field

[0001] The invention relates to the technical field of metal corrosion and protection, and in particular to a sacrificial anode device and its application and a raw material composition for a gel-based composite material. Background Art

[0002] Concrete is the most widely used and largest-volume building material in the world today. However, reinforced concrete structures in coastal areas are prone to steel corrosion due to the infiltration of chloride ions, which greatly shortens the service life of concrete structures. In addition, in my country, it is very common for marine engineering structures that have been in seawater environments for a long time to be damaged or even destroyed due to steel corrosion. Generally, the upper structure in the splash zone that has been in normal service for more than 10 years will be cracked due to steel corrosion.

[0003] Cathodic protection is considered to be the most effective and economical method to extend the durability of reinforced concrete, which mainly includes impressed current method and sacrificial anode method. The two methods have the same principle, which is to provide cathodic current to the steel bars in reinforced concrete to inhibit the anodic reaction of the steel bars, thereby achieving the electrochemical repair effect. Compared with the impressed current method, the sacrificial anode method has attracted more and more attention in recent years due to its advantages such as easy installation, no need for auxiliary power supply, and no need for frequent maintenance.

[0004] However, the sacrificial anode cathodic protection method has also exposed some shortcomings in practical applications: the sacrificial anode device in concrete cannot provide sufficient protection current due to its large resistance; the gel-based composite material in the device does not have enough pores to adsorb the anode corrosion products, causing the corrosion products to accumulate on the anode surface, resulting in anode passivation and deactivation, and unable to achieve long-term protection effect; the buried sacrificial anode device may have the risk of corrosion products expanding and cracking the concrete layer. In view of the above shortcomings, it is necessary to develop a safe and efficient sacrificial anode device to achieve long-term stable and effective protection of reinforced concrete structures. Summary of the invention

[0005] The purpose of the present invention is to overcome the problems of the prior art, such as too small output current, passivation deactivation, and expansion of corrosion products of the sacrificial anode device, and to provide a sacrificial anode device and its application, and a raw material composition for a gel-based composite material.

[0006] In the present invention, the micro-nano-sized porous structure means that the porosity of the material is greater than 5%, and it contains both micron-sized and nano-sized pores, and the proportion of micron-sized and nano-sized pores is not less than 10% respectively.

[0007] In order to achieve the above-mentioned object, the first aspect of the present invention provides a sacrificial anode device, wherein the sacrificial anode device comprises a metal sacrificial anode and a gel-based composite material wrapping the metal sacrificial anode, wherein the gel-based composite material has a porous structure of micro-nano size;

[0008] The porosity of the gel-based composite material is 24%-40%.

[0009] A second aspect of the present invention provides a raw material composition for a gel-based composite material.

[0010] A third aspect of the present invention provides a method for preventing metal corrosion, wherein the method comprises bringing the metal sacrificial anode in the sacrificial anode device described in the first aspect of the present invention into contact with a metal.

[0011] A fourth aspect of the present invention provides an application of the sacrificial anode device described in the first aspect of the present invention in the durability repair of concrete structures.

[0012] Through the above technical solution, the present invention has at least the following beneficial effects:

[0013] (1) The sacrificial anode device provided by the present invention has stable current output and high dechlorination efficiency, can reduce the risk of corrosion product expansion and can effectively alleviate the volume expansion of corrosion products, and can achieve long-term and stable protection of metals.

[0014] (2) The sacrificial anode device provided by the present invention has high dechlorination efficiency and can output a relatively high stable current for a long time by combining a metal sacrificial anode and a gel-based composite material.

[0015] (3) The gel-based composite material wrapped around the metal sacrificial anode can provide a strong alkaline activation environment, allowing the anode corrosion products to react with the hydroxide in the alkaline environment, reducing the risk of corrosion product expansion. At the same time, the material has a micro-nano-sized porous structure, which can further alleviate the volume expansion of the corrosion products.

[0016] (4) The device of the present invention also has the characteristics of stable performance, simple manufacturing process, high reliability, and simple installation, and is suitable for preventing metal corrosion and repairing the durability of concrete structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic structural diagram of a sacrificial anode device according to an embodiment of the present invention;

[0018] Figure 2 is a pore size distribution diagram of the gel-based composite materials of Examples 1-4 and Comparative Example 1;

[0019] Figure 3 Graphs of output current at different times after the sacrificial anode devices obtained in Example 3, Example 4, Comparative Example 2 and Comparative Example 3 are connected to the steel bars in the reinforced concrete structure contaminated by salt.

[0020] Description of Reference Numerals

[0021] 1 is a metal sacrificial anode, 2 is a gel-based composite material, and 3 is a metal connecting wire. DETAILED DESCRIPTION

[0022] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0023] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0024] A first aspect of the present invention provides a sacrificial anode device, wherein the sacrificial anode device comprises a metal sacrificial anode 1 and a gel-based composite material 2 wrapping the metal sacrificial anode, wherein the gel-based composite material has a porous structure of micro-nano size;

[0025] The porosity of the gel-based composite material is 24%-40%.

[0026] In the present invention, the gel-based composite material with a porous structure has an absorbing effect on the expansion force generated by the expansion of the corrosion products, which helps to alleviate the volume expansion of the corrosion products.

[0027] In some embodiments, in order to further alleviate the volume expansion of corrosion products, preferably, the porosity of the gel-based composite material is 25%-30%.

[0028] In the present invention, preferably, in the gel-based composite material, in the gel-based composite material, pores having a pore size greater than 0.01 μm and less than 5 μm account for 15%-63% by volume, more preferably 20%-60%.

[0029] In the present invention, preferably, in the gel-based composite material, the pores with a pore size greater than 5 μm and less than 200 μm account for 40%-90% by volume, more preferably 40%-80%.

[0030] In the present invention, preferably, the porosity of the gel-based composite material is 24%-40%, the pores with a pore size greater than 0.01 μm and less than 5 μm account for 15%-63%, and the pores with a pore size greater than 5 μm and less than 200 μm account for 40%-90%. When the porosity and pore size distribution of the gel-based composite material are as described above, the gel-based composite material can better alleviate the volume expansion of corrosion products, is more conducive to reducing the accumulation of corrosion products on the surface of the metal sacrificial anode, and improves the stability and service life of the sacrificial anode device.

[0031] In the present invention, preferably, the porosity of the gel-based composite material is 25%-30%, the pores with a pore size greater than 0.01 μm and less than 5 μm account for 20%-60%, and the pores with a pore size greater than 5 μm and less than 200 μm account for 40%-80%. When the porosity and pore size distribution of the gel-based composite material are as described above, the gel-based composite material can further alleviate the volume expansion of corrosion products, further reduce the accumulation of corrosion products on the surface of the metal sacrificial anode, and is more conducive to improving the stability and service life of the sacrificial anode device.

[0032] In the present invention, preferably, the gel-based composite material is formed by mixing a raw material composition for the gel-based composite material with water to obtain a slurry, and then applying the slurry to the metal sacrificial anode for hardening, wherein the raw material composition for the gel-based composite material contains a gelling material, an aggregate, a water reducing agent, an expansion agent, an air entraining agent, and an activator. The gel-based composite material obtained by using the raw material composition and the above-mentioned formation method has a porous structure of micro-nano size, which can alleviate the volume expansion of corrosion products and reduce the accumulation of corrosion products on the surface of the metal sacrificial anode, which is conducive to improving the stability and service life of the sacrificial anode device.

[0033] In the present invention, the hardening method is not particularly limited and may be a method conventionally used in the art, for example, the metal sacrificial anode may be fixed in a mold and the slurry may be injected.

[0034] In the present invention, preferably, in the raw material composition for the cementitious-based composite material, the weight ratio of the cementitious material, aggregate, water reducing agent, expansion agent, air entraining agent and activator is 1: (1-5): (0.0005-0.05): (0.01-0.5): (0.005-0.08): (0.1-0.8). When the weight ratio of each component of the raw material composition for the cementitious-based composite material is within the above range, the prepared cementitious-based composite material has a porous structure of micro-nano size, low resistivity and impedance, high stability, which is conducive to the degradation of corrosion products of the metal sacrificial anode, prolonging the time for the metal sacrificial anode to maintain activity, and is conducive to improving the stability and service life of the sacrificial anode device.

[0035] In some preferred embodiments of the present invention, the weight ratio of the cementitious material, aggregate, water reducing agent, expansion agent, air entraining agent and activator is 1: (1-3): (0.001-0.04): (0.05-0.3): (0.01-0.04): (0.1-0.4). When the weight ratio of each component of the raw material composition for the cementitious-based composite material is within the above range, the prepared cementitious-based composite material has a porous structure of micro-nano size, and has lower resistivity and impedance, higher stability, and is more conducive to degrading the corrosion products of the metal sacrificial anode, so that the metal sacrificial anode remains active for a longer time.

[0036] In the present invention, preferably, the raw material composition for the gel-based composite material further contains a conductive agent, which is more conducive to reducing the resistivity and impedance of the gel-based composite material.

[0037] In the present invention, preferably, the weight ratio of the gelling material to the conductive agent is 1:(0.001-0.05). When the weight ratio is within this range, the resistivity and impedance of the gelling-based composite material are low.

[0038] In the present invention, in order to further reduce the resistivity and impedance of the gel-based composite material, more preferably, the weight ratio of the gel-based material to the conductive agent is 1:(0.005-0.03).

[0039] In the present invention, the conductive agent is not particularly limited, as long as it can increase the conductivity of the gel-based composite material and reduce the resistivity and impedance of the gel-based composite material. In some preferred embodiments of the present invention, the conductive agent is selected from at least one of graphite powder, carbon fiber, graphene and carbon nanotubes.

[0040] In the present invention, preferably, the gelling material is selected from at least one of cement, gypsum and lime, for example, it can be a combination of cement, gypsum and lime, or a combination of cement and gypsum, or a combination of cement and lime. The addition of the gelling material helps to improve the stability of the gelling material, can provide an alkaline environment for the metal sacrificial anode, and reduce the expansion of the corrosion products of the metal sacrificial anode.

[0041] In the present invention, the cement is not particularly limited and can be cement commonly used in the art. Preferably, the cement is selected from at least one of Portland cement, aluminate cement and sulphoaluminate cement. The cement can be commercially available in a commonly used specification, for example, P.O42.5 Portland cement.

[0042] In the present invention, preferably, the weight ratio of cement to any other component in the cementitious material is 1:(1-40), more preferably 1:(2-24).

[0043] In the present invention, cement, gypsum and lime are used in a specific combination and a specific weight ratio, which helps to further improve the stability of the cementitious material, provide an alkaline environment for the metal sacrificial anode, and further reduce the expansion of corrosion products of the metal sacrificial anode.

[0044] In the present invention, preferably, the aggregate is quartz sand, which is not particularly limited and can be quartz sand commonly used in the art. Preferably, the quartz sand is at least one of 20 mesh quartz sand and 40 mesh quartz sand. In the present invention, the addition of the quartz sand is beneficial to controlling the shrinkage of the cementitious-based composite material.

[0045] In the present invention, preferably, the water reducer is selected from at least one of a lignin sulfonate water reducer and a polycarboxylate water reducer.

[0046] In some embodiments of the present invention, preferably, the lignin sulfonate water reducer is selected from at least one of sodium lignin sulfonate, calcium lignin sulfonate and potassium lignin sulfonate.

[0047] In the present invention, the polycarboxylate water-reducing agent is not particularly limited, and is a polycarboxylate water-reducing agent commonly used in the art, and can be commercially available, for example, a polycarboxylate water-reducing agent purchased from Nanjing Ruidi High-tech Co., Ltd. In the present invention, the polycarboxylate water-reducing agent can be at least one of a polyester polycarboxylate water-reducing agent, a polyether polycarboxylate water-reducing agent, and an amide / imide polycarboxylate water-reducing agent.

[0048] In the present invention, the addition of the water reducing agent can reduce the amount of water used and improve the fluidity and dispersibility of the cementitious-based composite material.

[0049] In the present invention, the swelling agent is not particularly limited and can be any swelling agent conventionally used in the art, but does not include low-activity magnesium oxide. Preferably, the swelling agent is selected from at least one of sodium bentonite, lithium bentonite, calcium bentonite, montmorillonite, kaolin and vermiculite. In the present invention, the swelling agent can compensate for the shrinkage of the gel-based composite material.

[0050] In the present invention, the air entraining agent is selected from at least one of cellulose ether and hydrogen peroxide. In the present invention, the addition of the air entraining agent is beneficial to improving the microporous structure in the gel-based composite material, so that the gel-based composite material is not easy to crack after the volume expansion of the corrosion product of the metal sacrificial anode.

[0051] In the present invention, in order to further improve the microporous structure in the gel-based composite material, preferably, the cellulose ether is selected from at least one of methyl cellulose, hydroxypropyl methyl cellulose and hydroxyethyl cellulose.

[0052] In the present invention, the activator is a strong base, for example, it can be an alkali metal hydroxide, calcium hydroxide, strong barium oxide, etc. The composition of the activator can include but is not limited to a strong base compound. In some embodiments of the present invention, preferably, the activator is at least one of lithium hydroxide, sodium hydroxide and potassium hydroxide.

[0053] In the present invention, the activator can provide a strong alkaline environment for the metal sacrificial anode, degrading the corrosion products of the metal sacrificial anode while maintaining the long-term activity of the metal sacrificial anode in the gel-based composite material. In addition, the sacrificial anode device can select an activator that is non-corrosive to the protected metal according to the properties of the protected metal in a specific use environment.

[0054] In the present invention, the material of the metal sacrificial anode is not particularly limited, and can be any metal sacrificial anode material conventionally used in the art. In order to prepare a sacrificial anode device with higher output current and more stability, preferably, the metal sacrificial anode is selected from at least one of zinc alloy, magnesium alloy, aluminum alloy and magnesium-aluminum alloy, more preferably magnesium alloy and / or magnesium-aluminum alloy.

[0055] In the present invention, the shape of part or all of the cross section of the metal sacrificial anode 1 is not particularly limited, for example, the cross section may be partially or entirely circular, rectangular, triangular, polygonal, multi-angled, and irregular. In order to increase the contact area between the metal sacrificial anode and the gel-based composite material, for example, part or all of the cross section of the metal sacrificial anode 1 may be a polygon, such as a five-pointed star, a six-pointed star, or a cross, a cross, etc. In some embodiments of the present invention, the cross section of the metal sacrificial anode 1 is a six-pointed star (for example, a six-pointed star with a side length of 1-10 mm), but it should be understood that the shape is not limited thereto.

[0056] In the present invention, the length, width and height of the metal sacrificial anode 1 are not particularly limited and can be reasonably adjusted according to the use environment. In some embodiments of the present invention, the metal sacrificial anode is limited to a length of 60-100 mm, but it should be understood that the length is not limited thereto.

[0057] In the present invention, the sacrificial anode device may also include a conductive wire or other conductive medium. The addition of the conductive wire or other conductive medium can make the metal sacrificial anode of the sacrificial anode device contact with the protected metal, and electrons can flow between the metal sacrificial anode and the metal. For example, a metal connecting wire can be installed on the metal sacrificial anode, and the metal connecting wire is connected to the protected metal. Further, in order to install the metal connecting wire on the metal sacrificial anode, a through hole (for example, the diameter of the through hole can be 1-4 mm) can be set on the metal sacrificial anode. For example, a through hole is set along the axis of the metal sacrificial anode and the metal connecting wire is passed through the through hole. However, it should be understood that the installation method of the metal connecting wire is not limited to this. Moreover, when the metal connecting wire is installed on the metal sacrificial anode, the material of the metal connecting wire is not limited, as long as the metal sacrificial anode and the metal connecting wire have good electrical connectivity, for example, it can be a conventional conductive wire, such as a metal wire, and the metal wire can be a steel wire, a copper wire, an aluminum wire, etc.

[0058] In the present invention, the electrical connectivity refers to the ability to transfer charges between the metal sacrificial anode and the metal connecting wire.

[0059] In the present invention, the thickness of the gel-based composite material that wraps the metal sacrificial anode is not particularly limited, as long as it can wrap the metal sacrificial anode. In order to improve the current output stability of the sacrificial anode device, alleviate the volume expansion of the corrosion products, and make the gel-based composite material less prone to cracking after the volume expansion of the corrosion products of the metal sacrificial anode, preferably, the thickness of the gel-based composite material is 5-20mm, more preferably 5-10mm. The second aspect of the present invention provides a raw material composition for a gel-based composite material, wherein the components of the raw material composition are as described in the first aspect of the present invention.

[0060] A third aspect of the present invention provides a method for preventing metal corrosion, wherein the method comprises bringing the metal sacrificial anode in the sacrificial anode device described in the first aspect of the present invention into contact with a metal.

[0061] In the present invention, the contact method is not particularly limited, as long as electrons can flow between the metal sacrificial anode and the metal. For example, the metal sacrificial anode can be in contact with the metal through a conductive wire or other conductive medium. In an application scenario of the sacrificial anode device provided by the present invention, the sacrificial anode device can be installed with a metal connecting wire, and connected to the metal that needs to be protected in the marine engineering through the metal connecting wire. For example, the metal connecting wire installed on the metal sacrificial anode is connected to the steel bars in the reinforced concrete structure of the marine engineering. When the sacrificial anode device is used in this scenario, mortar can also be used to fill the space between the sacrificial anode device and the steel bars.

[0062] A fourth aspect of the present invention provides an application of the sacrificial anode device described in the first aspect of the present invention in the durability repair of concrete structures.

[0063] The application method may be to bury the sacrificial anode device described in the first aspect of the present invention in a corroded coastal reinforced concrete structure, or other methods may be used, not limited to those described above.

[0064] The present invention will be described in detail below through examples.

[0065] In the following examples, all materials used can be commercially available products.

[0066] Portland cement, grade: P.O42.5, manufacturer: Nanjing Zhonglian Cement Plant;

[0067] Quartz sand, 20 mesh, manufacturer: Rongsheng Quartz Sand Factory;

[0068] Hydrated lime, calcium hydroxide content of 90% by weight, manufacturer: Changzhou Jintan Dingsheng Building Materials Factory;

[0069] Sodium lignosulfonate, solid content 99% by weight, manufacturer: Nanjing Ruidi High-tech Company;

[0070] Polycarboxylate water reducer, solid content 35% by weight, manufacturer: Nanjing Ruidi High-tech Company;

[0071] Calcium-based bentonite, pH 8, manufacturer: Sishui County Yuexin Smelting and Casting Materials Factory;

[0072] Hydroxypropyl methylcellulose, hydroxypropyl content of 8% by weight, manufacturer: Kaimaoxing Cellulose Co., Ltd.

[0073] Graphite powder, mesh number 20, ash content 0.05% by weight, manufacturer: Shandong Guohua Chemical Co., Ltd.;

[0074] Low-activity magnesium oxide, water solubility 6.2 mg / L (0°C), manufacturer: Jinan Linghang Chemical Co., Ltd.;

[0075] Hydrogen peroxide, hydrogen peroxide content of 29% by weight, manufacturer: Nanjing Liante Chemical Co., Ltd.;

[0076] Lithium hydroxide, LiOH·H 2 O content is 97% by weight, manufacturer: Nanjing Qianze New Material Technology Co., Ltd.

[0077] Example 1

[0078] The raw materials and weight ratio of the cementitious composite material are: P.O42.5 silicate cement: slaked lime: gypsum: 20 mesh quartz sand: sodium wood sulfonate: calcium-based bentonite: hydroxypropyl methylcellulose: graphite powder: lithium hydroxide = 0.694: 0.028: 0.278: 1.5: 0.0278: 0.138: 0.0138: 0.028: 0.278;

[0079] Preparation method: (1) A hexagram-shaped magnesium alloy metal sacrificial anode with a length of 60 mm and a side length of 4 mm is connected to a metal wire by mechanical connection to ensure that the wire and the metal sacrificial anode have good electrical connectivity; (2) The raw materials of the gel-based composite material are weighed in proportion, first dry-mixed for 3 minutes, and then water is added and stirred to obtain a uniformly mixed slurry; (3) The metal sacrificial anode connected to the metal wire is wrapped with the uniformly mixed slurry in a hexagonal prism mold with a length of 90 mm and a side length of 15 mm, and the sacrificial anode device is demolded after hardening to obtain the sacrificial anode device.

[0080] The thickness of the gel-based composite material is 8 mm.

[0081] Example 2

[0082] The raw materials and weight ratio of the cementitious composite material are: P.O42.5 silicate cement: slaked lime: gypsum: 20 mesh quartz sand: polycarboxylate water reducer: calcium-based bentonite: hydrogen peroxide: graphite powder: lithium hydroxide = 0.694: 0.028: 0.278: 2: 0.00138: 0.278: 0.0138: 0.0416: 0.278;

[0083] Preparation method: (1) A hexagram-shaped magnesium alloy metal sacrificial anode with a length of 60 mm and a side length of 5 mm is connected to a metal wire by mechanical connection to ensure that the wire and the metal sacrificial anode have good electrical connectivity; (2) The raw materials of the gel-based composite material are weighed in proportion, dry-mixed for 3 minutes, and then water is added and stirred to obtain a uniformly mixed slurry; (3) The metal sacrificial anode connected to the metal wire is wrapped with the uniformly mixed slurry in a hexagonal prism mold with a length of 85 mm and a side length of 15 mm, and the sacrificial anode device is demolded after hardening to obtain the sacrificial anode device.

[0084] The thickness of the gel-based composite material is 8 mm.

[0085] Example 3

[0086] The raw materials and weight ratio of the cementitious composite material are: P.O42.5 silicate cement: gypsum: 20 mesh quartz sand: sodium wood sulfonate: calcium-based bentonite: hydroxypropyl methylcellulose: graphite powder: lithium hydroxide = 0.8: 0.2: 2: 0.03: 0.2: 0.02: 0.03: 0.3;

[0087] Preparation method: (1) A hexagram-shaped magnesium alloy metal sacrificial anode with a length of 70 mm and a side length of 5 mm is connected to a metal wire by mechanical connection to ensure that the wire and the metal sacrificial anode have good electrical connectivity; (2) The raw materials of the gel-based composite material are weighed in proportion, first dry-mixed for 2 to 5 minutes, and then water is added and stirred to obtain a uniformly mixed slurry; (3) The metal sacrificial anode connected to the metal wire is wrapped with the uniformly mixed slurry in a hexagonal prism mold with a length of 100 mm and a side length of 20 mm, and demolded after hardening to obtain a sacrificial anode device.

[0088] The thickness of the gel-based composite material is 8 mm.

[0089] Example 4

[0090] The raw materials and weight ratio of the cementitious composite material are: P.O42.5 silicate cement: gypsum: 20 mesh quartz sand: polycarboxylate water reducer: calcium-based bentonite: hydrogen peroxide: lithium hydroxide = 0.8: 0.2: 1.5: 0.001: 0.2: 0.03: 0.3;

[0091] Preparation method: (1) A hexagram-shaped magnesium alloy metal sacrificial anode with a length of 70 mm and a side length of 6 mm is connected to a metal wire by mechanical connection to ensure that the wire and the metal sacrificial anode have good electrical connectivity; (2) The raw materials of the gel-based composite material are weighed in proportion, first dry-mixed for 3 minutes, and then water is added and stirred to obtain a uniformly mixed slurry; (3) The metal sacrificial anode connected to the metal wire is wrapped with the uniformly mixed slurry in a hexagonal prism mold with a length of 100 mm and a side length of 30 mm, and demolded after hardening to obtain a sacrificial anode device.

[0092] The thickness of the gel-based composite material is 8 mm.

[0093] Comparative Example 1

[0094] The raw materials and weight ratio of the cementitious composite material are: P.O42.5 silicate cement: gypsum: 20 mesh quartz sand = 0.8:0.2:1;

[0095] Preparation method: (1) A hexagram-shaped magnesium alloy metal sacrificial anode with a length of 70 mm and a side length of 6 mm is connected to a metal wire by mechanical connection to ensure that the wire and the metal sacrificial anode have good electrical connectivity; (2) The raw materials of the gel-based composite material are weighed in proportion, first dry-mixed for 3 minutes, and then water is added and stirred to obtain a uniformly mixed slurry; (3) The metal sacrificial anode connected to the metal wire is wrapped with the uniformly mixed slurry in a hexagonal prism mold with a length of 100 mm and a side length of 30 mm, and demolded after hardening to obtain a sacrificial anode device.

[0096] The thickness of the gel-based composite material is 8 mm.

[0097] Comparative Example 2

[0098] It is a commercially available sacrificial anode device. The manufacturer is Zhejiang Yuxi Corrosion Control Co., Ltd.

[0099] Comparative Example 3

[0100] It is a commercially available sacrificial anode device. The manufacturer is Zhejiang Yuxi Corrosion Control Co., Ltd.

[0101] Comparative Example 4

[0102] The raw materials and weight ratio of the cementitious composite material are: P.O42.5 silicate cement: gypsum: 20 mesh quartz sand: polycarboxylate water reducer: calcium-based bentonite: lithium hydroxide = 0.8: 0.2: 1.5: 0.001: 0.2: 0.3;

[0103] Preparation method: (1) A hexagram-shaped magnesium alloy metal sacrificial anode with a length of 70 mm and a side length of 6 mm is connected to a metal wire by mechanical connection to ensure that the wire and the metal sacrificial anode have good electrical connectivity; (2) The raw materials of the gel-based composite material are weighed in proportion, first dry-mixed for 3 minutes, and then water is added and stirred to obtain a uniformly mixed slurry; (3) The metal sacrificial anode connected to the metal wire is wrapped with the uniformly mixed slurry in a hexagonal prism mold with a length of 100 mm and a side length of 30 mm, and demolded after hardening to obtain a sacrificial anode device.

[0104] The thickness of the gel-based composite material is 8 mm.

[0105] Comparative Example 5

[0106] The raw materials and weight ratio of the cementitious composite material are: P.O42.5 silicate cement: gypsum: 20 mesh quartz sand: polycarboxylate water reducer: calcium-based bentonite: hydrogen peroxide: lithium hydroxide = 0.8: 0.2: 4: 0.06: 0.7: 0.04: 0.45;

[0107] Preparation method: (1) A hexagram-shaped magnesium alloy metal sacrificial anode with a length of 70 mm and a side length of 6 mm is connected to a metal wire by mechanical connection to ensure that the wire and the metal sacrificial anode have good electrical connectivity; (2) The raw materials of the gel-based composite material are weighed in proportion, first dry-mixed for 3 minutes, and then water is added and stirred to obtain a uniformly mixed slurry; (3) The metal sacrificial anode connected to the metal wire is wrapped with the uniformly mixed slurry in a hexagonal prism mold with a length of 100 mm and a side length of 30 mm, and demolded after hardening to obtain a sacrificial anode device.

[0108] The thickness of the gel-based composite material is 8 mm.

[0109] Comparative Example 6

[0110] The raw materials and weight ratio of the cementitious composite material are: P.O42.5 silicate cement: gypsum: 20 mesh quartz sand: polycarboxylic acid water reducer: low-activity magnesium oxide: hydrogen peroxide: lithium hydroxide = 0.8: 0.2: 1.5: 0.001: 0.2: 0.03: 0.3;

[0111] Preparation method: (1) A hexagram-shaped magnesium alloy metal sacrificial anode with a length of 70 mm and a side length of 6 mm is connected to a metal wire by mechanical connection to ensure that the wire and the metal sacrificial anode have good electrical connectivity; (2) The raw materials of the gel-based composite material are weighed in proportion, first dry-mixed for 3 minutes, and then water is added and stirred to obtain a uniformly mixed slurry; (3) The metal sacrificial anode connected to the metal wire is wrapped with the uniformly mixed slurry in a hexagonal prism mold with a length of 100 mm and a side length of 30 mm, and demolded after hardening to obtain a sacrificial anode device.

[0112] The thickness of the gel-based composite material is 8 mm.

[0113] Test Case

[0114] (1) The gel-based composite materials of each embodiment and comparative example 1 were subjected to mercury intrusion testing to measure the distribution of the pore structure and porosity of the gel-based composite materials. The results are shown in Table 1. The pore size distribution of the gel-based composite materials was measured. The results are shown in Table 1. Figure 2 As shown; wherein the letter d represents the aperture.

[0115] (2) The sacrificial anode devices of the embodiments and comparative examples of the present invention were connected to the steel bars of a reinforced concrete structure that was contaminated by salt, and the initial chloride ion content of the salt-contaminated environment was 0.4% by weight. After the space between the sacrificial anode device and the steel bars was filled with mortar, the output current of the anode was continuously measured with a digital multimeter within 25 days. The results are shown in FIG. Figure 3 .

[0116] (3) Based on test example (2), a dechlorination test was carried out. According to the specification "Technical Specifications for Testing and Inspection of Concrete for Water Transport Engineering" (standard code: JTS / T 236-2019), the chloride ion content of the surface layer of reinforced concrete was measured, and compared with the initial chloride ion content, the dechlorination efficiency was calculated by the following formula. The test results are shown in Table 1.

[0117]

[0118] Among them, ω i represents the mass fraction (%) of chloride ions in concrete after dechlorination test, ω 0 It represents the mass fraction (%) of chloride ions in concrete before the dechlorination test.

[0119] Table 1

[0120]

[0121] Table 1 and Figure 2 The results show that the cementitious matrix composite material in the devices described in Examples 1-4 has a porous structure at the micro-nano scale and a high porosity. Generally speaking, compared with Comparative Examples 1-6, the proportion of pores with 0.01 μm < d < 5 μm is relatively small, while the proportion of pores with 5 μm < d < 200 μm is relatively large, which has a certain absorption effect on the expansion force generated by the expansion of corrosion products.

[0122] The results of the dechlorination efficiency at 25 days in Table 1 show that the dechlorination efficiency of the sacrificial anode devices described in Examples 1-4 is significantly higher than that of Comparative Examples 1-6, indicating that the sacrificial anode device provided by the present invention has a good dechlorination and rust inhibition effect and can achieve long-term dechlorination.

[0123] In Comparative Examples 1, 4-6, water reducing agent, expansive agent, air-entraining agent and activator are not added in Comparative Example 1, air-entraining agent is not added in Comparative Example 4, the addition amounts of water reducing agent and expansive agent in Comparative Example 5 are outside the preferred range of the present invention, and low-activity magnesium oxide is used as the expansive agent in Comparative Example 6. It can be seen from the results in Table 1 that when the composition or addition amount of the cementitious matrix composite material is not within the preferred range described in the present invention, the porosity of the cementitious matrix composite materials in Comparative Examples 1, 4-6 is lower, the proportion of pores with 0.01 μm < d < 5 μm is greater than that in Examples 1-4, and the proportion of pores with 5 μm < d < 200 μm is less than that in Examples 1-4. Such materials are not conducive to absorbing the expansion force generated by the expansion of corrosion products; moreover, compared with Examples 1-4, the dechlorination efficiency of the sacrificial anode devices obtained in Comparative Examples 1 and 4-6 is lower.

[0124] Figure 3 The results show that after the sacrificial anode device is connected to the steel bars in the reinforced concrete structure contaminated by salt, the output currents of Examples 3 and 4 are still higher than 0.6 mA at 25 days, and the current change trends of Examples 1 and 2 are close to those of Examples 3 and 4 and the output currents at 25 days are also higher than 0.6 mA; while the currents of Comparative Examples 2 and 3 (commercially available sacrificial anode devices) are extremely low at 25 days, and the currents of the sacrificial anode devices obtained in Comparative Examples 1, 4-6 are close to 0 at 25 days. The above results show that the sacrificial anode device described in the present invention can maintain a long-term high and stable output current, is not easily passivated and inactivated, and can achieve long-term stable protection of metals.

[0125] In summary, the present invention provides a sacrificial anode device. After the sacrificial anode device contacts the metal to be protected, it can achieve long-term dechlorination and rust inhibition and output a long-term high and stable current; the cementitious matrix composite material wrapping the metal sacrificial anode has a porous structure at the micro-nano scale and can effectively relieve the volume expansion of corrosion products.

[0126] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various specific technical features in any suitable manner. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations. However, these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A sacrificial anode device, It is characterized in that The sacrificial anode device comprises a metal sacrificial anode (1) and a gel-based composite material (2) wrapping the metal sacrificial anode, wherein the gel-based composite material has a porous structure of micro-nano size; The porosity of the gel-based composite material is 24%-40%.

2. The device according to claim 1, in, The porosity of the gel-based composite material is 25%-30%; Preferably, in the gel-based composite material, the pores with a pore size greater than 0.01 μm and less than 5 μm account for 15% to 63% by volume, more preferably 20% to 60%; Preferably, in the gel-based composite material, the pores with a pore size greater than 5 μm and less than 200 μm account for 40%-90% by volume, more preferably 40%-80%.

3. The device according to claim 1 or 2, in, The gel-based composite material is formed by mixing a raw material composition for the gel-based composite material with water to obtain a slurry, and then coating the slurry on the metal sacrificial anode for hardening, wherein the raw material composition for the gel-based composite material contains a gelling material, an aggregate, a water reducing agent, an expansion agent, an air entraining agent and an activator; Preferably, the weight ratio of cementitious material, aggregate, water reducing agent, expansion agent, air entraining agent and activator is 1: (1-5): (0.0005-0.05): (0.01-0.5): (0.005-0.08): (0.1-0.8); more preferably, it is 1: (1-3): (0.001-0.04): (0.05-0.3): (0.01-0.04): (0.1-0.4).

4. The device according to claim 3, in, The raw material composition for the gel-based composite material further contains a conductive agent; Preferably, the weight ratio of the gelling material to the conductive agent is 1:(0.001-0.05), more preferably 1:(0.005-0.03); Preferably, the conductive agent is selected from at least one of graphite powder, carbon fiber, graphene and carbon nanotubes.

5. The device according to claim 3, in, The cementitious material is selected from at least one of cement, gypsum and lime; Preferably, the cement is selected from at least one of silicate cement, aluminate cement and sulphoaluminate cement; Preferably, the weight ratio of cement to any other component in the cementitious material is 1:(1-40), more preferably 1:(2-24).

6. The device according to claim 3, in, The aggregate is quartz sand, preferably at least one of 20 mesh quartz sand and 40 mesh quartz sand.

7. The device according to claim 3, in, The water reducer is selected from at least one of a lignin sulfonate water reducer and a polycarboxylate water reducer; More preferably, the lignin sulfonate water reducer is selected from at least one of sodium lignin sulfonate, calcium lignin sulfonate and potassium lignin sulfonate; More preferably, the polycarboxylate water-reducing agent is selected from at least one of a polyester polycarboxylate water-reducing agent, a polyether polycarboxylate water-reducing agent and an amide / imide polycarboxylate water-reducing agent.

8. The device according to claim 3, in, The expansion agent is selected from at least one of sodium bentonite, lithium bentonite, calcium bentonite, montmorillonite, kaolin and vermiculite; Preferably, the air entraining agent is selected from at least one of cellulose ether and hydrogen peroxide; More preferably, the cellulose ether is selected from at least one of methyl cellulose, hydroxypropyl methyl cellulose and hydroxyethyl cellulose; Preferably, the activator is an alkali metal hydroxide, more preferably at least one of lithium hydroxide, sodium hydroxide and potassium hydroxide.

9. The device according to claim 1 or 2, in, The metal sacrificial anode is selected from at least one of zinc alloy, magnesium alloy, aluminum alloy and magnesium-aluminum alloy, preferably magnesium alloy and / or magnesium-aluminum alloy.

10. The device according to claim 1 or 2, in, The thickness of the gel-based composite material is 5-20 mm, preferably 5-10 mm.

11. A raw material composition for a gel-based composite material, It is characterized in that The ingredients of the raw material composition are as described in any one of claims 3-8.

12. A method for preventing metal corrosion, It is characterized in that The method comprises contacting the metal sacrificial anode of the sacrificial anode arrangement of any one of claims 1 to 10 with the metal.

13. Use of the sacrificial anode device according to any one of claims 1 to 10 in the durability repair of concrete structures.

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