Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
  • C25D5/10—Electroplating with more than one layer of the same or of different metals
  • C25D5/12—Electroplating with more than one layer of the same or of different metals at least one layer being of nickel or chromium
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
  • Y10T428/12708—Sn-base component
  • Y10T428/12722—Next to Group VIII metal-base component
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
  • Y10T428/12729—Group IIA metal-base component
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
  • Y10T428/12736—Al-base component
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
  • Y10T428/12771—Transition metal-base component
  • Y10T428/12861—Group VIII or IB metal-base component
  • Y10T428/12896—Ag-base component
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/12—All metal or with adjacent metals
  • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
  • Y10T428/12771—Transition metal-base component
  • Y10T428/12861—Group VIII or IB metal-base component
  • Y10T428/12944—Ni-base component

Definitions

• This invention relates to an abrasion resistant coating for an aluminum and aluminum alloy conductor and to a method for applying the coating.
• fretting due to either mechanical wear or corrosion.
• fretting is wear resulting from oscillating or vibratory motion of a limited amplitude.
• Another form of fretting results from actual wear, frictional changes,'
• Aluminum is particularly susceptible to fretting corrosion which is the formation of hard abrasive oxides (A1 as debris and by an excessive rate of oxygen absorption.
• A1 hard abrasive oxides
• the invention also comprises a method for applying the several layers in the indicated sequence.
• the first step comprises cleaning the surface with a caustic solution to remove oxides, dirt and the like, and removes about /2 to 1 mil of aluminum surface.
• the preferred solution forthis purpose is about 8 to 10 ounces of sodium hydroxide per gallon of water at F which is applied to the aluminum surface for a time of from about A to 1 minute.
• Other alkali metal hydroxides such as potassium hydroxide may be used.
• a chelating agent is preferably added to the solution to slow down the action: :A common chelating agent is ethylenediaminetetraacetic acid (EDTA). The advantage of the chelating agent is to maintain the material removed from the aluminum surface in solution.
• the second step is a water rinse to remove all traces of the caustic solution of the first step because the third step involves an acid solution.
• a thick viscous coating or smut of sodium zincate (Na ZnO adheres to the member. This coating is removed better by a double rinse in water.
• the third step is a surface cleaning or desmutting operation with an acid solution such as a 1:1 mixture of nitric acid (67%) in water for the purpose of deoxidizing and removing impurities in aluminum such as iron and manganese.
• an acid solution such as a 1:1 mixture of nitric acid (67%) in water for the purpose of deoxidizing and removing impurities in aluminum such as iron and manganese.
• hydrofluoric acid is preferably added to make the aluminum surface more uniformly active and to prevent blistering of some subsequently deposited metal, such as tin. The blistering often occurs due to poor metal preparation.
• the fourth step is another rinse in water to remove all traces of acid of the previous rinse, because the next step involves an alkaline bath.
• the fifth step has the dual purpose of activating the aluminum surface and depositing a thin layer of tin or zinc.
• the aluminum member is immersed in aqueous solution, the primary constituent of which is at least one tincontaining compound selected from the group consisting of a stannate of an alkali metal, such as sodium stannate and potassium stannate, together with a chelating agent such as EDTA.
• a chelating agent such as EDTA.
• the composition of the solution is shown in The constituents, sodium stannate and potassium stannate, may be used either alone or mixed to make up the required composition.
• Sodium stannate and potassium stannate used here and in subsequent steps may be used either in the anhydrous or the trihydrate form; it being immaterial, because the operating conditions required the solution to be maintained at an elevated temperature of from 75 to 85F with a preferred temperature of 80F.
• the immersion time may range from 15 to 45 seconds with a preferred time of 30 seconds.
• a partial or wholly substitute chelating agent is preferably used for stabilizing the time to prevent it from settling to the bottom of the container. It is a mixture of zinc acetate, Zn (C H O in an amount of about 2 ounces per gallon of water and m-cresolsulfonic acid in the amount of about 4 ounces per gallon of water.
• step 5 the surface of the aluminum member is completely activated and the protective layer of tin is deposited.
• the weight of tin deposited varies from about 0.1 to 0.3 mg/in
• the aluminum member is immersed in an aqueous solution having at least one zinccontaining compound, such as zinc oxide and sodium hydroxide.
• the immersion time may range from to 45 seconds with a preferred time of about 30 seconds at a temperature of from 75 to 85F with a preferred temperature of 80F.
• the composition of the zinc solution is shown in Table II as follows:
• the chelating agent is preferably used as a stabilizer of the solution.
• the sixth step is the application of a coating of copper or a copper-base alloy. Where in step 5 tin is applied, a coating of a copper-base alloy such as a bronze strike is applied on the tin in step 6. However, where zinc is applied in Step 5, a copper strike is applied in step 6. Where tin is applied, a rinse between steps 5 and 6 is unnecessary because the solutions of both steps are alkaline. But where zinc is applied, a rinse is preferred before the application of copper.
• the sixth step is ac complished by immersing the aluminum member into an electrolyte consisting essentially of a stannate of an alkali metal such as sodium stannate and copper cyanide. A partial or complete substitute for sodium stannate may be potassium stannate.
• Table III The constituents and the amounts used for the bronze strike are shown in Table III as follows:
• the seventh step is a water rinse for the purpose of The ninth stepvis a water rinse removing the bronze or copper str1ke solutions and for preventing contamination of the nickel plate solution which is the eighth step.
• the tenth step is the application of tin or silver as The eighth step is the application of a relatively thick preferred. A rinse in two baths of cold water is required layer of nickel on the bronze or copper strike. The alubefore plating of tin or silver.
• minum member is immersed in electrolyte having the Where the choice is tin, the copper plated aluminum constituents listed in Table VI as follows: member is immersed into the plating solution having Table VI the formula and operating conditions set forth in Tables VIII and IX as follows:
• Nickel Plate Table VIII (Ounces per gallon of water) Constituent Preferred Range Tm Plate Nickel sulfamate 50-60 20-70 (Ounces P gallon 0f Water) Boric Acid 4-4.5 3.5-5 f rre Ra g A i pini Agent Q06 0 05 Q 07 Constituent Compositlon Composition KOI'I 2 l-4 K SnO and/or The thickness of the resulting nickel plate ranges Na sno 28 26-28 from about 0.0001 to 0.0005 inch, the preferred thick- Tm metal equwalem Table ness being 0.0002 inch.
• the thickness of the outer tin plate or coating may range from 0.0001 to 0.0006 inch, the preferred thick- Although nickel plated from the nickel sulfamate is r1885 being (3-0005 inchdi l d, i k l m b l t d f the l ti
• the copper-plated aluminum member is placed in 5 the silver plating electrolyte having a formula and control conditions as set forth in Tables X and XI as fol- Watts Type Bath lows: High-pH Table X Nickel sulfate 32 oz/gal Nickel chloride 6 oz/gal Boric acid 4 oz/gal Silver Plate F (Ounces per gallon of water) Temperature 1 Constituent Preferred Range Current denisty 20 -l00 ASF Hard Nickel Bath
• the eleventh step is the final rinse in hot water after which the member is dried in hot air.
• the resulting protective coating provided in the method set forth above provides a corrosion and abrasion resistant plating for stabs or bus ducts when bus bars are subjected to 30,000 consecutive abrasion tests, ie. involving sliding wear.
• the multiple layered coating of this invention satisties the foregoing problem of fretting with attendent problems.
• the bronze or copper plating provides a suitable substrate for the nickel strike.
• the nickel plating has a tri-fold advantage including the establishment of a base for the silver or tin which is subsequently applied, corrosion prevention, and providing a harder base for sliding friction on the stab surface as indicated in Table XII.
• Silver serves as a lubricant and resists fretting better than tin and does it with a thinner coating.
• a composite article comprising an aluminum alloy member having an abrasion resistant coating on the surface thereof, said coating consisting essentially of an inner layer of a metal selected from the group consisting of tin and zinc, a first intermediate layer of a metal selected from a group consisting of copper and bronze, a second intermediate layer of nickel, and an outer layer of a metal selected from a group consisting of tin and silver.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Electroplating Methods And Accessories (AREA)
• Chemically Coating (AREA)
• Non-Insulated Conductors (AREA)

Priority Applications (3)

Applications Claiming Priority (1)

Publications (2)

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ID=23580874

Family Applications (1)

Country Status (2)

Cited By (23)

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Citations (5)

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• 1973
  • 1973-09-20 US US399766A patent/US3915667A/en not_active Expired - Lifetime
• 1974
  • 1974-09-19 JP JP10720874A patent/JPS568919B2/ja not_active Expired

Patent Citations (5)

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