EP3835442A1 - Alloy for use in a sacrificial anode and a sacrificial anode - Google Patents
Alloy for use in a sacrificial anode and a sacrificial anode Download PDFInfo
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- EP3835442A1 EP3835442A1 EP20204306.3A EP20204306A EP3835442A1 EP 3835442 A1 EP3835442 A1 EP 3835442A1 EP 20204306 A EP20204306 A EP 20204306A EP 3835442 A1 EP3835442 A1 EP 3835442A1
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- aluminium
- based alloy
- sacrificial anode
- zinc
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C21/00—Alloys based on aluminium
- C22C21/10—Alloys based on aluminium with zinc as the next major constituent
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- C23F13/00—Inhibiting corrosion of metals by anodic or cathodic protection
- C23F13/02—Inhibiting corrosion of metals by anodic or cathodic protection cathodic; Selection of conditions, parameters or procedures for cathodic protection, e.g. of electrical conditions
- C23F13/06—Constructional parts, or assemblies of cathodic-protection apparatus
- C23F13/08—Electrodes specially adapted for inhibiting corrosion by cathodic protection; Manufacture thereof; Conducting electric current thereto
- C23F13/12—Electrodes characterised by the material
- C23F13/14—Material for sacrificial anodes
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- C23F2213/00—Aspects of inhibiting corrosion of metals by anodic or cathodic protection
- C23F2213/30—Anodic or cathodic protection specially adapted for a specific object
- C23F2213/31—Immersed structures, e.g. submarine structures
Definitions
- the present invention relates to an aluminium-based alloy for use in a sacrificial anode and a sacrificial anode produced from the aluminium-based alloy.
- Cathodic protection using sacrificial anodes is a well-known technique within a number of areas including ships, vessels and offshore constructions, e.g. oil exploitation rigs.
- the electrochemical process taking place is generally along the following scheme for a ferrous material: Fe ⁇ Fe 2+ + 2e - O 2 + 2H 2 O + 4e - ⁇ 4OH - 2H 2 O + 2e - ⁇ H 2 + 2OH -
- ferrous hydroxide also known as rust: Fe 2+ + 2OH - ⁇ Fe(OH) 2
- anode materials are aluminium or zinc or alloys comprising aluminium or zinc as the main component, but other materials may be used as alternatives to zinc and aluminium, such as magnesium as well as alloys containing magnesium.
- the sacrificial anodes should be of a type suitable to the environment of operation, i.e. taking into consideration the chemical composition of the environment and also the temperature. Furthermore, the size of the anode(s) as well as their mutual positioning are relevant to consider in order to provide a satisfactory protection.
- the alloy compositions described herein are designed to have high operating efficiencies to make the alloy as cost-effective as possible, high current output to enable high and long-lasting performance for a given weight of anode (energy density), and optimized operating potential, which will vary depending on the application.
- An important added benefit is that in the alloys of this invention the content of zinc is very low.
- the most used commercial aluminium anode alloy is aluminium-5% zinc-0.02% indium.
- This alloy is specified in MIL-DTL-24779 and has proven to be very effective in worldwide climates to protect a variety of materials including iron, steel, and aluminium piers, ships, off-shore rigs, and bridges among other applications. It is approximately 90% efficient, which is lower than pure zinc, which is about 98% efficient, but much higher than magnesium, which is about 60% efficient.
- An object of the present invention is to provide an alloy for sacrificial anodes which is environmental friendly and can be produced in a cost-effective manner.
- a further object is to provide a sacrificial anode based on aluminium and with a very low amount of zinc, which provides good properties in respect of cathodic protection of more noble metals.
- the present invention relates to an aluminium-based alloy for use in a sacrificial anode, comprising
- balance indicates that aluminium constitutes the amount of the alloy which is required to reach 100% by weight, e.g. if the combined amount of zinc, indium, gallium, iron, copper, and optional impurities constitutes 0.85% by weight, the amount of aluminium constitutes 99.15% by weight.
- the alloy may also comprise elements in form of impurities in an amount of maximum 0.02% by weight of each element.
- the impurities may e.g. be constituted by magnesium, mangan, silicium, chrome, cadmium, tin, boron and other elements.
- the impurities may originate from the aluminium grade used.
- the high amount of aluminium combined with low amounts of zinc, indium, gallium, iron, and copper provides an alloy for a sacrificial anode with good properties and which is significantly lesser harmful to the environment than sacrificial anodes comprising higher amounts of zinc, such as above 1% by weight or more.
- the amount of zinc may vary between 0.01 - 0.8% by weight, such as between 0.01 - 0.5% by weight of zinc.
- the amount of zinc may constitute between 0.05 - 0.8%, such as between % 0.08 - 0.8%, or even between 0.1 - 0.5%, such as between 0.2 - 0.5% by weight.
- the amount of zinc may also vary between 0.3 - 0.8%, such as between 0.4 - 0.8%, or between 0.5 - 0.8% by weight.
- maximum indicates that the specified percentage is the maximum content of the metal in the alloy.
- the aluminium-based alloy comprises:
- the amount of impurities present in the alloy may be larger than the amount of some of the individual elements: zinc, indium, gallium, iron, and copper, the lower presence of these metals, however, appears to improve the electrochemical properties of the alloy.
- the aluminium in the aluminium-based alloy generally has a high purity, and in an embodiment the aluminium has a purity of at least 99,0% by weight.
- the aluminium has a purity of at least 99,5% by weight.
- the aluminium may have purities in the ranges 99.00 to 99.99% by weight, preferably in the ranges 99.50 to 99.99% by weight, such as purities in the ranges 99.90 to 99.99 % by weight.
- the aluminium-based alloy according to the invention has an excellent electrochemical efficiency, and in an embodiment the aluminium-based alloy has an electrochemical efficiency above 1500 Ah/kg, preferably above 2000 Ah/kg, such as above 2500 Ah/kg, when tested according to the standard DvN RP B401 (DvN RP B401 Annex B).
- the aluminium-based alloy according to the invention has low potential (potential vs. Ag/AgCI), and in an embodiment the potential is even lower than -800mV, such as lower than -1000mV.
- the aluminium-based alloy according to the invention is able to provide a very good cathodic protection to more noble metals, e.g. steel.
- the invention also relates to the use of an aluminium-based alloy in a sacrificial anode for protecting metallic constructions in a humid and marine environment, said aluminium-based alloy comprising:
- the aluminium may have purities in the ranges 99.00 to 99.99% by weight, preferably purities in the ranges 99.50 to 99.99% by weight, such as a purity in the ranges 99.90 to 99.99% by weight.
- the use according to the invention provides sacrificial anodes with an excellent electrochemical efficiency, and in an embodiment the anodes with the aluminium-based alloy has an electrochemical efficiency above 1500 Ah/kg, preferably above 2000 Ah/kg, such as above 2500 Ah/kg, when tested according to the standard DvN RP B401 (DvN RP B401 Annex B).
- the use according to the invention also provides sacrificial anodes with low potential (potential vs. Ag/AgCI), and in an embodiment of the invention the potential is lower than -1000mV.
- sacrificial anodes with low potential (potential vs. Ag/AgCI), and in an embodiment of the invention the potential is lower than -1000mV.
- use of the aluminium-based alloy according to the invention provides sacrificial anodes with very good cathodic protection to more noble metals, e.g. steel.
- the invention further relates to a sacrificial anode for protecting metallic constructions in a humid and marine environment, said sacrificial anode comprising
- said sacrificial anode for protecting metallic constructions in a humid and marine environment, said sacrificial anode comprising
- said sacrificial anode for protecting metallic constructions in a humid and marine environment, said sacrificial anode comprising:
- the aluminium in the aluminium-based alloy may have purities in the ranges 99.00 to 99.99% by weight, preferably purities in the ranges 99.50 to 99.99% by weight, such as a purity in the ranges 99.90 to 99.99% by weight.
- the sacrificial anode according to the invention has an excellent electrochemical efficiency, and in an embodiment the sacrificial anode with the aluminium-based alloy has an electrochemical efficiency above 1500 Ah/kg, preferably above 2000 Ah/kg, such as above 2500 Ah/kg, when tested according to the standard DvN RP B401 (DvN RP B401 Annex B).
- the sacrificial anode has a low potential (potential vs. Ag/AgCI), and in an embodiment the potential is lower than -1050mV.
- potential vs. Ag/AgCI potential vs. Ag/AgCI
- use of the aluminium-based alloy provides sacrificial anodes with very good cathodic protection to more noble metals.
- Figure 1A shows an embodiment of a sacrificial anode 10.
- the sacrificial anode comprises the aluminium alloy 12 shaped as a bar and with connection pieces 14 at each end.
- the connection pieces 14 comprise holes by which the sacrificial anode 10 can be connected to the item which requires cathodic protection by means of bolts or screws.
- Figure 1B shows another embodiment of a sacrificial anode 10 with sacrificial alloy 12 and connectors 14.
- the connectors 14 can be welded to the item that requires cathodic protection.
- Figure 1C shows yet an embodiment of a sacrificial anode 10 with sacrificial alloy 12 and connectors 14.
- the connecters 14 are "S"-shaped and can be attached by welding to the structure which requires cathodic protection.
- the amount of the sacrificial alloy 12 shaped as a bar may be 100 kg or more.
- a sacrificial anode according to the invention was produced using the aluminium-based alloy with the approximate composition: Zinc: 0.5% by weight Indium: 0.02% by weight Gallium: 0.05% by weight Iron: 0.06% by weight Copper: 0.002% by weight Impurities: 0.03% by weight in total Aluminium: balance
- the aluminium-based alloy was shaped into a cylindrical rod constituting a sacrificial anode, and the electrochemical efficiency and the potential were determined.
- the sacrificial anode had an electrochemical efficiency above 2500 Ah/kg when tested according to DvN RP B401.
- the sacrificial anode had a potential (potential vs. Ag/AgCI) lower than -1050mV.
- the sacrificial anode provided very good properties in respect of cathodic protection for metallic structures.
Abstract
Description
- The present invention relates to an aluminium-based alloy for use in a sacrificial anode and a sacrificial anode produced from the aluminium-based alloy.
- Cathodic protection using sacrificial anodes is a well-known technique within a number of areas including ships, vessels and offshore constructions, e.g. oil exploitation rigs.
- The electrochemical process taking place is generally along the following scheme for a ferrous material:
Fe → Fe2+ + 2e-
O2 + 2H2O + 4e- → 4OH-
2H2O + 2e- → H2 + 2OH-
- In most environments, the hydroxide ions and ferrous ions combine to form ferrous hydroxide, also known as rust:
Fe2+ + 2OH- → Fe(OH)2
- It is desired to prevent or at least reduce the deterioration of the ferrous material, as this is the main structural material of the construction in question. Therefore, a sacrificial metal ranking lower in the electrochemical scheme, and therefore being more prone to the electrochemical reaction, is placed in electrical connection with the main construction and protects this main construction from deterioration. The most often used anode materials are aluminium or zinc or alloys comprising aluminium or zinc as the main component, but other materials may be used as alternatives to zinc and aluminium, such as magnesium as well as alloys containing magnesium.
- Relevant areas of deployment are numerous; however, constructions in operation in seawater are in particular vulnerable to corrosion and will almost always be protected from such corrosion by means of cathodic protection using sacrificial anodes. Ships, vessels and offshore oil exploitation constructions are well-known examples of such.
- The sacrificial anodes should be of a type suitable to the environment of operation, i.e. taking into consideration the chemical composition of the environment and also the temperature. Furthermore, the size of the anode(s) as well as their mutual positioning are relevant to consider in order to provide a satisfactory protection.
- Many offshore oil exploitation constructions, pipelines or other equipment are from their very first installation provided with a cathodic protection system using sacrificial anodes, and most often the dimensioning of the anodes is designed for the design life time of the oil exploitation construction, meaning that no further exchange of the sacrificial anodes is foreseen. The oil exploitation constructions, pipelines or other equipment are however in many cases kept in operation well beyond the initial design life time, meaning that the cathodic protection obtained through the sacrificial anodes will disappear when the anodes are consumed after a certain time. For this situation, there is a need for exchanging or retrofitting the anodes of the offshore oil exploitation construction, pipelines or other equipment with new functional anodes to ensure the cathodic protection for a further life extension of the oil exploitation construction, pipelines or other equipment.
- There are a number of ways of ensuring the cathodic protection of the construction. Normally the anodes are mounted directly on the construction with a mutual distance, ensuring the most efficient protection according to the design criteria as mentioned above. Another way of ensuring the correct function is by placing the anodes remotely from the construction to be protected and connecting each anode electrically to the designed connection position of the construction, pipelines or other equipment.
- When retrofitting anodes to an offshore construction, pipelines or other equipment the remote positioning of the anodes is often the most effective way of doing this and therefore the preferred way of ensuring the continued cathodic protection.
- It is known in the art to provide an anode construction for the purpose of retrofitting anodes to an offshore construction, pipelines or other equipment where the previously known construction comprises a framework with the anodes placed in mutually distanced positions to ensure the proper functioning of the cathodic protection. The anodes are connected to suitable connection points of the construction to be protected by means of suitable wiring. Such previously known anode construction is relatively bulky and therefore difficult to transport from the production site to the actual operational site.
- The alloy compositions described herein are designed to have high operating efficiencies to make the alloy as cost-effective as possible, high current output to enable high and long-lasting performance for a given weight of anode (energy density), and optimized operating potential, which will vary depending on the application. An important added benefit is that in the alloys of this invention the content of zinc is very low. The most used commercial aluminium anode alloy is aluminium-5% zinc-0.02% indium. This alloy is specified in MIL-DTL-24779 and has proven to be very effective in worldwide climates to protect a variety of materials including iron, steel, and aluminium piers, ships, off-shore rigs, and bridges among other applications. It is approximately 90% efficient, which is lower than pure zinc, which is about 98% efficient, but much higher than magnesium, which is about 60% efficient.
- Unfortunately, zinc is an aquatic toxin and contains residual cadmium from the mining process. Zinc is known to be toxic for marine plants and animals. Consequently, there is a raising demand for alloys in which the content of zinc is very low, but which still provide the same outstanding efficiency, current output and energy density. The alloy of this invention has the potential to replace the aluminium-zinc-indium alloy for use as described above. Moreover, zinc is also more expensive than aluminium. Thus, replacing the amount of zinc in an alloy with aluminium, reduces the cost of producing the alloy. Corrosion protective anodes comprising high amount of aluminium are e.g. disclosed in the patent documents
US 2012/0084208 A1 andUS 2019/0078179 A1 . - An object of the present invention is to provide an alloy for sacrificial anodes which is environmental friendly and can be produced in a cost-effective manner.
- A further object is to provide a sacrificial anode based on aluminium and with a very low amount of zinc, which provides good properties in respect of cathodic protection of more noble metals.
- Consequently, the present invention relates to an aluminium-based alloy for use in a sacrificial anode, comprising
- between 0.01 - 0.8% by weight of zinc,
- between 0.01 - 0.04% by weight of indium,
- between 0.02 - 0.1% by weight of gallium,
- between 0.01 - 0.08% by weight of iron,
- between 0.0005 - 0.003% by weight of copper,
- elements in form of impurities in an amount of maximum 0.02% by weight of each element, and
- balance aluminium.
- The term "balance" indicates that aluminium constitutes the amount of the alloy which is required to reach 100% by weight, e.g. if the combined amount of zinc, indium, gallium, iron, copper, and optional impurities constitutes 0.85% by weight, the amount of aluminium constitutes 99.15% by weight.
- The alloy may also comprise elements in form of impurities in an amount of maximum 0.02% by weight of each element. The impurities may e.g. be constituted by magnesium, mangan, silicium, chrome, cadmium, tin, boron and other elements. The impurities may originate from the aluminium grade used.
- It has surprisingly appeared that the high amount of aluminium combined with low amounts of zinc, indium, gallium, iron, and copper provides an alloy for a sacrificial anode with good properties and which is significantly lesser harmful to the environment than sacrificial anodes comprising higher amounts of zinc, such as above 1% by weight or more.
- The amount of zinc may vary between 0.01 - 0.8% by weight, such as between 0.01 - 0.5% by weight of zinc. The amount of zinc may constitute between 0.05 - 0.8%, such as between % 0.08 - 0.8%, or even between 0.1 - 0.5%, such as between 0.2 - 0.5% by weight. The amount of zinc may also vary between 0.3 - 0.8%, such as between 0.4 - 0.8%, or between 0.5 - 0.8% by weight.
- In an embodiment the aluminium-based alloy for use in a sacrificial anode comprises:
- maximum 0.8 %by weight of zinc,
- maximum 0.04% by weight of indium,
- maximum 0.1% by weight of gallium,
- maximum 0.08% by weight of iron,
- maximum 0.003% by weight of copper,
- elements in form of impurities in an amount of maximum 0.02% by weight of each element, and
- balance aluminium.
- The term "maximum" indicates that the specified percentage is the maximum content of the metal in the alloy.
- In an embodiment, the aluminium-based alloy comprises:
- between 0.01 - 0.5% by weight of zinc,
- between 0.01 - 0.04% by weight of indium,
- between 0.02 - 0.1% by weight of gallium,
- between 0.01 - 0.08% by weight of iron,
- between 0.0005 - 0.003% by weight of copper,
- elements in form of impurities in an amount of maximum 0.02% by weight of each element, and
- balance aluminium.
- Although the amount of impurities present in the alloy may be larger than the amount of some of the individual elements: zinc, indium, gallium, iron, and copper, the lower presence of these metals, however, appears to improve the electrochemical properties of the alloy.
- The aluminium in the aluminium-based alloy generally has a high purity, and in an embodiment the aluminium has a purity of at least 99,0% by weight.
- In an embodiment of the aluminium-based alloy according to the invention, the aluminium has a purity of at least 99,5% by weight.
- In the aluminium-based alloy according to the invention, the aluminium may have purities in the ranges 99.00 to 99.99% by weight, preferably in the ranges 99.50 to 99.99% by weight, such as purities in the ranges 99.90 to 99.99 % by weight.
- The aluminium-based alloy according to the invention has an excellent electrochemical efficiency, and in an embodiment the aluminium-based alloy has an electrochemical efficiency above 1500 Ah/kg, preferably above 2000 Ah/kg, such as above 2500 Ah/kg, when tested according to the standard DvN RP B401 (DvN RP B401 Annex B).
- Moreover, the aluminium-based alloy according to the invention has low potential (potential vs. Ag/AgCI), and in an embodiment the potential is even lower than -800mV, such as lower than -1000mV. Thus, the aluminium-based alloy according to the invention is able to provide a very good cathodic protection to more noble metals, e.g. steel.
- The invention also relates to the use of an aluminium-based alloy in a sacrificial anode for protecting metallic constructions in a humid and marine environment, said aluminium-based alloy comprising:
- between 0.01 - 0.8% by weight of zinc,
- between 0.01 - 0.04% by weight of indium,
- between 0.02 - 0.1% by weight of gallium,
- between 0.01 - 0.08% by weight of iron,
- between 0.0005 - 0.003% by weight of copper,
- elements in form of impurities in an amount of maximum 0.02% by weight of each element, and
- balance aluminium.
- In an embodiment the invention relates to use of an aluminium-based alloy comprising:
- maximum 0.8% by weight of zinc,
- maximum 0.04% by weight of indium,
- maximum 0.1% by weight of gallium,
- maximum 0.08% by weight of iron,
- maximum 0.003% by weight of copper,
- elements in form of impurities in an amount of maximum 0.02% by weight of each element, and
- balance aluminium.
- In an further embodiment the invention relates to use of an aluminium-based alloy comprising:
- between 0.01 - 0.8% by weight of zinc,
- between 0.01 - 0.04% by weight of indium,
- between 0.02 - 0.1% by weight of gallium,
- between 0.01 - 0.08% by weight of iron,
- between 0.0005 - 0.003% by weight of copper,
- elements in form of impurities in an amount of maximum 0.02% by weight of each element, and
- balance aluminium.
- According to the use of the aluminium-based alloy according to the invention, the aluminium may have purities in the ranges 99.00 to 99.99% by weight, preferably purities in the ranges 99.50 to 99.99% by weight, such as a purity in the ranges 99.90 to 99.99% by weight.
- The use according to the invention provides sacrificial anodes with an excellent electrochemical efficiency, and in an embodiment the anodes with the aluminium-based alloy has an electrochemical efficiency above 1500 Ah/kg, preferably above 2000 Ah/kg, such as above 2500 Ah/kg, when tested according to the standard DvN RP B401 (DvN RP B401 Annex B).
- Moreover, the use according to the invention also provides sacrificial anodes with low potential (potential vs. Ag/AgCI), and in an embodiment of the invention the potential is lower than -1000mV. Thus, use of the aluminium-based alloy according to the invention provides sacrificial anodes with very good cathodic protection to more noble metals, e.g. steel.
- The invention further relates to a sacrificial anode for protecting metallic constructions in a humid and marine environment, said sacrificial anode comprising
- between 0.01 - 0.8% by weight of zinc,
- between 0.01 - 0.04% by weight of indium,
- between 0.02 - 0.1% by weight of gallium,
- between 0.01 - 0.08% by weight of iron,
- between 0.0005 - 0.003% by weight of copper,
- elements in form of impurities in an amount of maximum 0.02% by weight of each element, and
- balance aluminium.
- In an embodiment of the sacrificial anode for protecting metallic constructions in a humid and marine environment, said sacrificial anode comprising
- between 0.01 - 0.5% by weight of zinc,
- between 0.01 - 0.04% by weight of indium,
- between 0.02 - 0.1% by weight of gallium,
- between 0.01 - 0.08% by weight of iron,
- between 0.0005 - 0.003% by weight of copper,
- elements in form of impurities in an amount of maximum 0.02% by weight of each element, and
- balance aluminium.
- In a further embodiment of the sacrificial anode for protecting metallic constructions in a humid and marine environment, said sacrificial anode comprising:
- maximum 0.8% by weight of zinc,
- maximum 0.04% by weight of indium,
- maximum 0.1% by weight of gallium,
- maximum 0.08% by weight of iron,
- maximum 0.003% by weight of copper,
- elements in form of impurities in an amount of maximum 0.02% by weight of each element, and
- balance aluminium.
- The aluminium in the aluminium-based alloy may have purities in the ranges 99.00 to 99.99% by weight, preferably purities in the ranges 99.50 to 99.99% by weight, such as a purity in the ranges 99.90 to 99.99% by weight.
- The sacrificial anode according to the invention has an excellent electrochemical efficiency, and in an embodiment the sacrificial anode with the aluminium-based alloy has an electrochemical efficiency above 1500 Ah/kg, preferably above 2000 Ah/kg, such as above 2500 Ah/kg, when tested according to the standard DvN RP B401 (DvN RP B401 Annex B).
- The sacrificial anode has a low potential (potential vs. Ag/AgCI), and in an embodiment the potential is lower than -1050mV. Thus, use of the aluminium-based alloy provides sacrificial anodes with very good cathodic protection to more noble metals.
- The invention will now be described in further details with reference to the drawings in which:
-
Figure 1A shows a first embodiment of a sacrificial anode; -
Figure 1B shows a second embodiment of a sacrificial anode; and -
Figure 1C shows a third embodiment of a sacrificial anode. - The figures are only intended to illustrate the principles of the invention and may not be accurate in every detail. Moreover, parts which do not form part of the invention may be omitted. The same reference numbers are used for the same parts throughout.
-
Figure 1A shows an embodiment of asacrificial anode 10. The sacrificial anode comprises thealuminium alloy 12 shaped as a bar and withconnection pieces 14 at each end. Theconnection pieces 14 comprise holes by which thesacrificial anode 10 can be connected to the item which requires cathodic protection by means of bolts or screws. -
Figure 1B shows another embodiment of asacrificial anode 10 withsacrificial alloy 12 andconnectors 14. Theconnectors 14 can be welded to the item that requires cathodic protection. -
Figure 1C shows yet an embodiment of asacrificial anode 10 withsacrificial alloy 12 andconnectors 14. Theconnecters 14 are "S"-shaped and can be attached by welding to the structure which requires cathodic protection. The amount of thesacrificial alloy 12 shaped as a bar may be 100 kg or more. - A sacrificial anode according to the invention was produced using the aluminium-based alloy with the approximate composition:
Zinc: 0.5% by weight Indium: 0.02% by weight Gallium: 0.05% by weight Iron: 0.06% by weight Copper: 0.002% by weight Impurities: 0.03% by weight in total Aluminium: balance - The aluminium-based alloy was shaped into a cylindrical rod constituting a sacrificial anode, and the electrochemical efficiency and the potential were determined.
- The sacrificial anode had an electrochemical efficiency above 2500 Ah/kg when tested according to DvN RP B401.
- The sacrificial anode had a potential (potential vs. Ag/AgCI) lower than -1050mV.
- Thus, the sacrificial anode provided very good properties in respect of cathodic protection for metallic structures.
Claims (10)
- An aluminium-based alloy for use in a sacrificial anode, characterized in that it comprisesbetween 0.01 - 0.8% by weight of zinc,between 0.01 - 0.04% by weight of indium,between 0.02 - 0.1% by weight of gallium,between 0.01 - 0.08% by weight of iron,between 0.0005 - 0.003% by weight of copper,elements in form of impurities in an amount of maximum 0.02% by weight of each element, andbalance aluminium.
- Aluminium-based alloy according to claim 1 comprising:between 0.01 - 0.5% by weight of zinc,between 0.01 - 0.04% by weight of indium,between 0.02 - 0.1% by weight of gallium,between 0.01 - 0.08% by weight of iron,between 0.0005 - 0.003% by weight of copper,elements in form of impurities in an amount of maximum 0.02% by weight of each element, andbalance aluminium.
- Aluminium-based alloy according to claim 1 or 2, wherein the aluminium has a purity of at least 99,0% by weight.
- Aluminium-based alloy according to claim 1 or 2, wherein the aluminium has a purity of at least 99,5% by weight.
- Aluminium-based alloy according to claim 1 or 2, wherein the aluminium has a purity in the ranges 99.90 to 99.99% by weight.
- Aluminium-based alloy according to anyone of the preceding claims, wherein the aluminium-based alloy has an electrochemical efficiency above 1500 Ah/kg, preferably above 2000 Ah/kg, such as above 2500 Ah/kg, when tested according to DvN RP B401.
- Use of an aluminium-based alloy in a sacrificial anode for protecting metallic constructions in a humid and marine environment, said aluminium-based alloy comprising:between 0.01 - 0.8% by weight of zinc,between 0.01 - 0.04% by weight of indium,between 0.02 - 0.1% by weight of gallium,between 0.01 - 0.08% by weight of iron,between 0.0005 - 0.003% by weight of copper,elements in form of impurities in an amount of maximum 0.02% by weight of each element, andbalance aluminium.
- Use according to claim 7, wherein the aluminium-based alloy has an electrochemical efficiency above 1500 Ah/kg, preferably above 2000 Ah/kg, such as above 2500 Ah/kg, when tested according to DvN RP B401.
- A sacrificial anode for protecting metallic constructions in a humid and marine environment, said sacrificial anode comprises an aluminium-based alloy comprisingbetween 0.01 - 0.8% by weight of zinc,between 0.01 - 0.04% by weight of indium,between 0.02 - 0.1% by weight of gallium,between 0.01 - 0.08% by weight of iron,between 0.0005 - 0.003% by weight of copper,elements in form of impurities in an amount of maximum 0.02% by weight of each element, andbalance aluminium.
- Sacrificial anode according to claim 9, wherein the aluminium-based alloy has an electrochemical efficiency above 1500 Ah/kg, preferably above 2000 Ah/kg, such as above 2500 Ah/kg, when tested according to DvN RP B401.
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EP19215052.2A EP3835441A1 (en) | 2019-12-10 | 2019-12-10 | Alloy for use in a sacrificial anode and a sactificial anode |
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EP19215052.2A Withdrawn EP3835441A1 (en) | 2019-12-10 | 2019-12-10 | Alloy for use in a sacrificial anode and a sactificial anode |
EP20204306.3A Pending EP3835442A1 (en) | 2019-12-10 | 2020-10-28 | Alloy for use in a sacrificial anode and a sacrificial anode |
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Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4885045A (en) * | 1987-06-16 | 1989-12-05 | Comalco Aluminum Limited | Aluminium alloys suitable for sacrificial anodes |
US20120084208A1 (en) | 2007-12-31 | 2012-04-05 | Jonathan Robert Powell | Methods and system for cardholder initiated transactions |
US20130084208A1 (en) * | 2011-09-30 | 2013-04-04 | Questek Innovations Llc | Aluminum-based alloys |
US20190078179A1 (en) | 2017-09-14 | 2019-03-14 | United States Of America As Represented By The Secretary Of The Navy | Aluminum Anode Alloy |
-
2019
- 2019-12-10 EP EP19215052.2A patent/EP3835441A1/en not_active Withdrawn
-
2020
- 2020-10-28 EP EP20204306.3A patent/EP3835442A1/en active Pending
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4885045A (en) * | 1987-06-16 | 1989-12-05 | Comalco Aluminum Limited | Aluminium alloys suitable for sacrificial anodes |
US20120084208A1 (en) | 2007-12-31 | 2012-04-05 | Jonathan Robert Powell | Methods and system for cardholder initiated transactions |
US20130084208A1 (en) * | 2011-09-30 | 2013-04-04 | Questek Innovations Llc | Aluminum-based alloys |
US20190078179A1 (en) | 2017-09-14 | 2019-03-14 | United States Of America As Represented By The Secretary Of The Navy | Aluminum Anode Alloy |
Non-Patent Citations (1)
Title |
---|
ANSHUMAN SHARMA ET AL: "and thermodynamic modelling of alloying effects on activity of sacrificial aluminium anodes", CORROSION SCIENCE, OXFORD, GB, vol. 53, no. 5, 20 January 2011 (2011-01-20), pages 1724 - 1731, XP028156793, ISSN: 0010-938X, [retrieved on 20110128], DOI: 10.1016/J.CORSCI.2011.01.046 * |
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