CN100404725C - Metal oxide anode components for marine cathodic protection - Google Patents

Abstract

The invention relates to a metal oxide anode assembly for cathodic protection of ships. The anode assembly is composed of an anode body, a conductive rod, an insulating bracket and a fixed frame. Metal oxide conductive coating, solid titanium rods or copper core composite titanium rods are welded on the back of the conductive rods, the anode bracket is made of glass fiber reinforced epoxy resin composite material through hot molding, the anode body is pressed with a fixed frame and fixed with bolts , The fixed frame is made of extremely corrosion-resistant polymer material. The marine auxiliary anode assembly is suitable for installation on the hull with a small radius of curvature. It has good electrochemical performance, is not easy to damage, and can work reliably for a long time; it also has the characteristics of long service life, good stability, and easy installation; it is suitable for Prevent seawater corrosion of hulls, rudder plates and propeller propellers; it can also be used to prevent corrosion of metal structures such as floating docks, barges and hydraulic gates.

Description

Metal oxide anode components for marine cathodic protection

Technical field:

The invention relates to a metal oxide anode assembly, which is suitable for the applied current cathodic protection system of ships, and is used to prevent seawater corrosion of ship hulls, rudder plates, and propeller propellers, and can also be used to prevent metal oxides such as floating docks, barges, and hydraulic gates. The invention relates to corrosion of structures, specifically a metal oxide anode assembly for ship cathodic protection belonging to the technical field of electrochemical protection.

technical background:

The combination of cathodic protection and coating can effectively prevent the corrosion of metal structures such as ships in seawater. According to different methods of providing protective current, cathodic protection can be divided into two methods: sacrificial anode and impressed current. The sacrificial anode method is to generate cathodic protection current by connecting the electronegative anode material to the hull and dissolving itself through galvanic action; while the impressed current cathodic protection method provides the required protection through an external DC power supply Current, which is characterized by high driving voltage, large output current, long protection life, and can automatically adjust the size of the output current with changes in external working conditions, so that the protected metal structure is always in the best protection state. For ships, since the impressed current cathodic protection method only needs to install a small number of auxiliary anodes, it will not produce obvious resistance to the navigation of the ship. Based on the above-mentioned advantages, impressed current cathodic protection anti-corrosion systems are usually used for large ocean-going ships or fast ships with high speed requirements.

Impressed current cathodic protection system usually consists of power supply equipment, auxiliary anode and reference electrode and other parts. The auxiliary anode assembly is an important part of the hull impressed current cathodic protection system, and its function is to transfer the protection current provided by the power supply equipment to the surface of the protected hull and appendages through the medium. The auxiliary anode assembly usually consists of an anode body for drainage and an anode bracket for fixing and insulating.

The material used as an anode body should have a small consumption rate, good stability and long service life as well as good electrical conductivity and electrochemical activity, and it should also have good economy and high performance-price ratio. At present, the anode body materials often used in the impressed current cathodic protection system of ships mainly include lead-silver alloy and platinum-titanium, platinum-niobium, and platinum-tantalum composite anodes. Lead-silver alloy anodes are slightly soluble anodes, but they are heavy, heavy, and inconvenient to install. Moreover, lead is toxic and pollutes the environment. It is used less and less in actual engineering, and is gradually favored by anode materials with better performance. replace. Platinum-titanium, platinum-niobium, and platinum-tantalum composite anodes are formed by compounding a platinum layer on an inert metal titanium, niobium, or tantalum substrate by metallurgical drawing or rolling, and have good electrochemical performance and long service life. But the preparation process is complex and expensive.

When the anode works in seawater, electrochemical reactions will occur on the surface to generate chlorine, oxygen, hypochlorous acid, etc., so the anode bracket must have good chemical stability under this medium condition, and it should also have sufficient dielectric strength. electrical properties and good mechanical properties. Polyvinyl chloride, nylon, laminated phenolic fiberglass, etc. have been used as anode insulation bracket materials. These materials are prone to aging, unstable performance, and failure when they work for a long time.

Impressed current cathodic protection systems for ships often use strip-shaped auxiliary anode components, some of which can even reach several meters in length. Although it can reduce the water connection resistance, it cannot be installed on parts of the hull with large curvature such as the bow or stern, and Because these parts are in contact with the copper propeller or the coating is easily damaged, a large protective current is often required, so the auxiliary anode assembly should be installed in these parts as much as possible. In addition, since the auxiliary anode assembly is directly installed on the outer surface of the hull, it not only affects the streamline of the hull, but is also vulnerable to mechanical damage such as collisions, especially for ships sailing in ice regions.

Invention content:

Aiming at the deficiencies in the above-mentioned existing marine auxiliary anode assembly, the purpose of the present invention is to provide a metal oxide auxiliary anode assembly for cathodic protection, which is suitable for installation on the ship hull with large curvature and has good electrochemical performance. performance, not easy to damage, and can work reliably for a long time.

In order to realize the purpose of the above invention, the main structure of the present invention is composed of anode body, conductive rod, anode bracket, fixed frame, sealing ring, sealing packing, junction box and anode cable. The working surface of the anode body is a disc-shaped titanium The substrate has a thickness of 1.5-15mm, and the purity of titanium is 99%-100%. Its surface is compounded with conductive ceramic mixed metal oxides; the back of the anode body is welded with conductive rods; the anode body is placed on the anode formed by hot pressing of composite materials On the bracket, press it with a fixed frame and fix it with bolts, and then fix it in the prefabricated groove on the hull. The ends of the bolts are sealed with sealing putty, and the fixed frame is made of extremely corrosion-resistant polymer materials such as polytetrafluoroethylene, etc. .

The diameter of the anode assembly is smaller than the distance between the ribs of the hull, and the size of its working surface area is tailored according to the required displacement.

The titanium matrix, that is, the working surface of the titanium anode body is covered with conductive ceramic mixed metal oxides, which are mainly composed of one or more of platinum group metal oxides such as ruthenium oxide, iridium oxide, and palladium oxide, together with titanium oxide, tin oxide, and oxide oxide. One or more mixtures of non-noble metal oxides such as tantalum, the content of noble metal oxides is 30%-100% (molar ratio); the conductive rod that plays a conductive role welded on the back of the titanium substrate connects the anode cable and the anode body For electrical connection, the conductive rod is made of solid titanium rod or copper core composite titanium rod.

The anode bracket with insulating function is made of glass fiber reinforced epoxy resin composite material, modified epoxy resin is used as the basic material, chopped glass fiber is used as the reinforcement material, talc powder is used as filler, silane coupling agent and high temperature curing agent are added. Formed by hot pressing process; the anode body with the conductive rod is embedded in the molded anode bracket, and is packaged and fixed with epoxy resin coating material. The insulated anode bracket can prevent the short circuit between the conductive rod and the sealing cover on the hull; the anode body The edge of the working surface is inlaid with a fixed frame made of polytetrafluoroethylene; the anode body penetrates into the hull and is double-sealed with an O-ring and sealing packing, and the anode cable is welded to the conductive rod through the sealing packing.

Compared with the background technology, the present invention has the following advantages: (1) titanium is used as the anode substrate, which has good mechanical properties and is easy to process; the anode is light in weight, can replace the heavy lead-silver alloy anode, and is convenient for handling and installation; 2) The conductive mixed metal oxide is used as the anode coating, so that the anode has extremely high stability and low consumption rate, so it can have a long service life; due to the high electrochemical activity of the oxide coating , can adopt larger working current density and lower power supply output voltage, so it has higher efficiency; and the price is cheaper than platinum anode, which can save precious metal resources; (3) uses glass fiber reinforced epoxy resin composite material and The anode bracket is manufactured by hot pressing forming process, and the PTFE frame with extremely high corrosion resistance is used, so it has excellent mechanical properties, water resistance, electrical insulation properties and chemical stability, and can work reliably for a long time; (4 ) adopts a disc-shaped anode assembly and inlaid installation, which is suitable for installation on curved hull parts such as the bow and stern, and is not prone to mechanical damage such as collision; (5) Since the anode body and the anode bracket are packaged in the factory Integral components increase its reliability and facilitate on-site installation. (6) The part where the anode penetrates into the hull is double-sealed with O-ring and packing, which improves the watertight performance and improves the working reliability of the auxiliary anode.

Description of drawings:

Fig. 1 is a schematic diagram of the principle of the main structure of the present invention.

Detailed ways;

The implementation of the present invention consists of an anode body 1, a conductive rod 2, an anode bracket 3, a fixed frame 4, a sealing ring 5, a sealing packing 6, a junction box 7 and an anode cable 8 electrochemically combined into an integral structure, and its anode body 1 The working surface of the working surface adopts a disc-shaped titanium substrate, the surface of which is compounded with conductive ceramic mixed metal oxide, and the conductive rod 2 of solid titanium rod or copper core composite titanium rod is welded on the back; the anode bracket 3 is made of aging-resistant, water-absorbing Low heat-pressed glass fiber reinforced epoxy resin composite material; the anode body 1 is pressed and fixed with a fixed frame 4, and the fixed frame 4 is made of an extremely corrosion-resistant polymer material such as polytetrafluoroethylene.

The purity of the titanium anode body should be higher than 99%. Compared with other anode base materials such as niobium and tantalum, it has a lower price and a higher performance-price ratio, and can fully meet the needs of cathodic protection of ships in seawater. The anode body 1 adopts a disc-shaped structure, which has a smaller overall structural size under the condition of the same working area, and is convenient to be embedded on the surface of the hull, so that the surface of the hull is streamlined to reduce the resistance of water flow during navigation. Because the anode body 1 does not protrude from the surface of the hull, it is not easily subject to mechanical damage such as collisions. Due to the small size of the anode body 1 , it is convenient to form and install the anode assembly, especially suitable for installation on a surface with curvature such as the bow or stern of a ship. The diameter of the anode assembly should be less than the distance between the ribs of the hull. The size of the working surface area of the anode body 1 directly affects the discharge rate of the anode, and can be tailored within the allowable size range of the anode body according to the required discharge rate. The titanium thickness of the titanium anode body should ensure that the anode body 1 has sufficient structural strength.

The working surface of the titanium substrate is covered with conductive ceramic mixed metal oxides, which are mainly composed of one or more of platinum group metal oxides such as ruthenium oxide, iridium oxide, and palladium oxide and non-conductive materials such as titanium oxide, tin oxide, and tantalum oxide. One or more mixed forms of noble metal oxides, and the content of noble metal oxides should not be less than 30% (molar ratio); when the content of noble metal oxides is less than this value, the electrochemical performance of the mixed metal oxide anode will be reduced will deteriorate significantly. Due to the good electrical conductivity, large specific surface area and high chemical and electrochemical stability of the mixed metal oxide coating, the titanium-based oxide coating anode has higher electrocatalytic activity and Smaller consumption rate, it is a high-performance auxiliary anode material, and its price is lower than that of platinum anode.

A conductive rod 2 is welded on the back of the titanium anode body 1. The conductive rod 2 plays a conductive role and electrically connects the anode cable 8 and the anode body 1 together. The conductive rod 2 is made of a solid titanium rod or a copper core composite titanium rod. Lower the resistance.

The anode bracket 3 is made of glass fiber reinforced epoxy resin composite material. Modified epoxy resin is selected as the basic material of the bracket, chopped glass fiber is used as the reinforcement material, talcum powder is used as the filler, and a silane coupling agent is added to improve its water resistance. The anode bracket 3 has excellent mechanical properties, water resistance and chemical stability, and has good electrical insulation properties.

The anode body 1 with the conductive rod 2 is embedded in the molded anode bracket 3, and is packaged and fixed with epoxy resin coating material. The conductive rod 2 is packaged in the insulating anode bracket 3, which can prevent the conductive rod 2 from contacting with the The seal on the hull short circuited.

In order to reduce the damage to the anode bracket caused by the precipitation of chlorine gas on the anode surface, and to fix the auxiliary anode on the hull, a polytetrafluoroethylene fixed frame 4 is inlaid at the edge of the working surface of the anode body 1, and the polytetrafluoroethylene fixed frame 4 The composite material anode bracket 3 is connected by bolts and fixed on the hull, and the ends of the bolts are sealed with sealing putty; due to the embedded installation structure, the anode is not easily subject to mechanical damage such as collisions, and is not fluid drag on the hull surface.

The part where the anode penetrates into the hull is double-sealed with O-rings and fillers to prevent seawater from penetrating into the cable junction box. The anode cable 8 is welded to the conductive rod 2 of the auxiliary anode through the cable sealing filler 6 .

Example:

A titanium plate is used as the anode substrate, with a diameter of Φ300mm and a thickness of 10mm. A titanium conductive rod 2 with a diameter of 12mm is welded on the back, and the working surface of the anode body 1 is coated with ruthenium oxide, iridium oxide, titanium oxide, tantalum oxide, A mixed metal oxide conductive coating of tin oxide, wherein the content of ruthenium oxide and iridium oxide is 30% (mol). The anode bracket 3 is made of glass fiber reinforced epoxy resin composite material through compression molding. The anode body 1 is packaged in the molded anode bracket 3 with epoxy resin to make an anode assembly. The anode fixing frame 4 is made of polytetrafluoroethylene, the auxiliary anode assembly is installed in the pre-prepared groove at the stern of the hull, and fixed with 6 bolts. According to the amount of protection current required by the design, a total of 2 auxiliary anode assemblies are used, which are respectively installed on both sides of the stern of the hull. A potentiostat with a rated output of 80A/16V is used as the power supply, the positive pole is connected to the auxiliary anode, the negative pole is connected to the hull, and silver/silver chloride is used as the reference electrode to measure the protection potential of the hull. The results show that when the output current of each auxiliary anode is 20A, the protection potential of the hull has reached -0.8V, indicating that the hull is in a good state of protection. The auxiliary anode assembly has stable working performance and can meet the anticorrosion protection requirements of the hull (including attachments such as propellers).

Claims (4)

1. A metal oxide anode assembly for cathodic protection of a ship is formed by combining an anode body, a conductive rod, an anode bracket, a fixed frame, a sealing ring, a sealing packing, a junction box and an anode cable, and is characterized in that the anode body works The surface is a disc-shaped titanium substrate, its thickness is 1.5-15mm, and the purity of titanium is 99%-100%. Its surface is compounded with conductive ceramic mixed metal oxides; the back of the anode body is welded with conductive rods; The material is hot-pressed and formed on the anode bracket, which is pressed with a fixed frame and fixed with bolts and then fixed in the prefabricated groove on the hull. The ends of the bolts are sealed with sealing putty, and the fixed frame is made of extremely corrosion-resistant polymer material. Made of vinyl fluoride; the diameter of the anode assembly is smaller than the distance between the ribs of the hull, and the size of its working surface area is tailored according to the required displacement. 2. The metal oxide anode assembly for marine cathodic protection according to claim 1 is characterized in that the titanium substrate, that is, the working surface of the titanium anode body, is covered with conductive ceramic mixed metal oxides, made of ruthenium oxide, iridium oxide, palladium oxide One or more of them are mixed with one or more of titanium oxide, tin oxide, and tantalum oxide; the conductive rod that plays a conductive role welded on the back of the titanium substrate electrically connects the anode cable and the anode body, and the conductive rod The structural components are solid titanium rods or copper core composite titanium rods. 3. The metal oxide anode assembly for marine cathodic protection according to claim 1, characterized in that the anode bracket with insulation function is made of glass fiber reinforced epoxy resin composite material, and modified epoxy resin is the basic material, with short Cut glass fiber as reinforcement, talcum powder as filler, add silane coupling agent and high-temperature curing agent to form by hot pressing process; anode body with conductive rod is embedded in molded anode bracket, and epoxy resin coating material Encapsulation and fixing are carried out, and the insulating anode bracket prevents the conductive rod from short circuiting with the sealing cover on the hull. 4. The metal oxide anode assembly for marine cathodic protection according to claim 1, characterized in that the working surface edge of the anode body is inlaid with a fixed frame of polytetrafluoroethylene composition; the anode body penetrates the hull and uses an O-shaped sealing ring It is double-sealed with the sealing packing, and the anode cable is welded to the conductive rod through the sealing packing.

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