Classifications

• • 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
• • 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
• • 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

Definitions

• This invention relates to aluminous metal galvanic anodes for the cathodic protection of metals and an alloy composition for the same to improve their performance and relates particularly to consumable anodes of an aluminium base alloy for the cathodic protection of nonaluminous metal structures exposed to the corrosive action of aqueous media, and particularly aqueous saline media, and a composition for improving the output of such anodes.
• Cathodic protection systems are well known in which a metal article immersed in an electrolyte is protected from corrosion by means of a sacrificial or a consumable anode which is also immersed in the electrolyte and is electrically connected to the metal structure (cathode) which is to be protected. Protection against corrosion is particularly important when the metal article is exposed to the corrosive action of an aqueous saline media. Sacrificial anodes are employed to provide cathodic protection for such structures as steel pipe lines, ship hulls, ship ballast tanks, metal sea walls, and drilling rigs.
• Sacrificial or consumable anodes are generally made in any desired shape or size to suit the structure to be protected and must be composed of a metal which is anodic to the metal body to be protected.
• the anodes may be in wrought or cast form but the latter has generally been preferred.
• Some convenient means for attaching the anode to the article to be protected is usually necessary such as an embedded metal core strap, rod or cable.
• the object of this invention is to provide an improved aluminum base alloy galvanic anode which has a longer useful life per unit weight of anode material than prior commercial aluminum base alloy anodes.
• Another object is to provide an aluminum base alloy galvanic anode having both a high current efficiency and a substantially constant low electrode potential during its life to continuously protect the metal structures with which it is connected.
• the zinc component of the alloy is necessary to provide the desired electrode potential for the anode. Smaller amounts than 3.5% do not supply the desired characteristics in the anode while more than 9.0% does not produce any added improvement in performance.
• the indium component also favorably afiects the behavior of the anodes by helping to maintain a high current output over the life of the anode. Smaller amounts than the stated minimums have an insignificant effect upon the performance of the anodes whereas larger quantities have an adverse elfect.
• the anodes can be made in either cast or wrought form but generally it is most convenient to produce them in the form of castings since the supporting rod or cable can be cast in place.
• the sand or permanent mold casting procedures are generally most convenient to employ.
• anodes will vary with the type of installation, and anodes for commercial purposes generally weigh between 10 and 50 pounds.
• the alloy anodes described above are capable of yielding more ampere hours per pound of metal consumed at a substantially constant potential under the same conditions than anodes of an aluminum-5.5% zinc alloy of the type heretofore used for cathodic protection purposes.
• My improved aluminum base alloy anodes provide a substantially constant difierence of 0.2 to 0.4 volt in electrode potential between the anodes and a steel structure and thus afford adequate protection on the one hand, while on the other hand avoiding what is known as over protection.
• the anodes Were placed in circuit with a conventional device for delivering and maintaining a constant current density in which the potential is automatically adjusted to compensate for variations in resistance.
• the externally applied potential did not exceed a few volts and the current density was maintained at 2 milliamperes per square inch of anode surface.
• the current values were ascertained by use of milliampere meter in the circuit.
• all the anodes were removed, cleaned and weighed to determine the loss of metal. It was found that the anodes of Lot #1 lost 2.8% of their weight and those of Lot #2 lost 1.7% of their weight.
• a galvanic anode in the non-heat treated condition composed of an aluminum base alloy consisting essentially of aluminum, 3.5% to 9.0% by weight of zinc and 0.008% to 0.05% by weight of indium, the total of all impurities not being over 0.50%, said anode in the ascast or as-worked condition being characterized by a higher current efiiciency than the same anode without indium.
• a galvanic anode in the non-heat treated condition composed of an aluminum base alloy consisting essentially of aluminum, 3.5% to 9.0% by weight of zinc and 0.008% to 0.05% by weight of indium, and containing as impurities a maximum of 0.20% iron, 0.20% silicon, 0.02% copper, and 0.05% each of all other impurities, the total amount of said impurities not exceeding 0.5 0%, said anode being characterized by a higher current efficiency than the same anode without indium.
• a galvanic anode in the non-heat treated condition composed of an aluminum base alloy consisting of aluminum, 3.5% to 9.0% by weight of zinc, 0.008% to 0.05% by weight of indium and 0.05% to 0.2% by Weight of tin, and containing as impurities a maximum of 0.20% iron, 0.20% silicon, 0.02% copper and 0.05% each of all other impurities, the total amount of said impurities not exceeding 0.50%
• An aluminum alloy for galvanic anodes consisting of less than 0.05 and more than 0.008 weight percent indium; 3.5 to 9.0 weight percent zinc, the balance being aluminum.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Prevention Of Electric Corrosion (AREA)

Priority Applications (8)

Applications Claiming Priority (1)

Publications (1)

Family

ID=22502354

Family Applications (1)

Country Status (6)

Cited By (8)

Citations (8)

Family Cites Families (2)

• 0
  • NL NL279640D patent/NL279640A/xx unknown
  • NL NL125961D patent/NL125961C/xx active
• 1961
  • 1961-10-05 US US143041A patent/US3418230A/en not_active Expired - Lifetime
• 1962
  • 1962-05-25 DE DEA40301A patent/DE1294140B/de active Pending
  • 1962-05-26 ES ES277727A patent/ES277727A1/es not_active Expired
  • 1962-05-30 GB GB20790/62A patent/GB962494A/en not_active Expired
  • 1962-06-05 BE BE618568A patent/BE618568A/fr unknown

Patent Citations (8)

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