US2883311A - Method and composition for treating aluminum and aluminum alloys - Google Patents

Method and composition for treating aluminum and aluminum alloys Download PDF

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US2883311A
US2883311A US614779A US61477956A US2883311A US 2883311 A US2883311 A US 2883311A US 614779 A US614779 A US 614779A US 61477956 A US61477956 A US 61477956A US 2883311 A US2883311 A US 2883311A
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solution
aluminum
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alloys
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Halpert David
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Vertol Aircraft Corp
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Vertol Aircraft Corp
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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
    • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
    • C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
    • C23G1/02—Cleaning or pickling metallic material with solutions or molten salts with acid solutions
    • C23G1/12—Light metals
    • C23G1/125—Light metals aluminium

Definitions

  • This invention relates to the surface treatment of aluminum and aluminum base alloys for the removal of oxide films, and more particularly to the composition and method for treating aluminum surfaces so as to maintain a low electrical resistance for a substantial period of time.
  • a primary object of this invention to provide a chemical deoxidizing solution for removing the oxide coatings on aluminum and its alloys wherein the composition agents are readily controllable at the room operating temperature of the solution, and further, wherein the dimensional tolerance losses of the aluminum are positively controlled by the use of an inhibitor.
  • a further object of the invention is to provide an aluminum deoxidizing solution comprising an aqueous acid solution containing fluorides, chromates or dichromates and nitric acid in certain well defined proportions and ranges of concentration for producing an electrically low resistant surface without excessively removing the aluminum base metal.
  • deoxidizing solution is used throughout the description in place of chemical cleaning solution because it more accurately defines the function of the solution, which is to remove the characteristic oxide coating on aluminum and its alloys.
  • the composition of the deoxidizing solution consists of relatively high concentrations of nitric acid and fluorides in combination with hexavalent chromium ions.
  • Nitric acid (70% concentrate) is preferably used in an amount within the range of from about 80 to 90 cc. per liter.
  • the fluoride constituent may be introduced in the form of a simple or complex fluoride which is soluble in nitric acid without producing objectionable precipitates with the chromium ions or the aluminum ions that may find their way into the solution by metal dissolution.
  • Sodium fluoride is preferably used for supplying the fluoride ion since it is easily handled and relatively eco nomical.
  • the fluoride ion concentration of the deoxidizing solution should be maintained at an amount approximately equivalent to that obtained with l to 45 grams of sodium fluoride per liter of solution. Also, by varying the amount of sodium fluoride introduced into solution, it is possible to control the solution pH value, which for best results should be maintained within a range of 0.2 to 1.7, the preferred pH range being 0.35 to 0.9.
  • Chromic acid is a preferred constituent for supplying the hexavalent chromium ion which acts as the inhibitor for the otherwise vigorously reacting mixture of fluorides and nitric acid.
  • the hexavalent chromium ion when properly proportioned with the fluoride ion and the nitric acid, tends to regulate the dissolving action of the deoxidizing solution on the aluminum such that its dimensional losses do not exceed 0.0002" even for an immersion time of approximately 5 minutes in a 60 to 95 F. solution. It was found that the chromium ion concentration should be maintained in an amount approximately equivalent to that obtained with 1 to 400 grams of anhydrous chromic acid per liter of solution.
  • the deoxidizing solution of the present invention essentially comprises:
  • the surface Prior to the immersion of the aluminum or its alloy in the deoxidizing solution, the surface is preferably cleaned of heavy oil, grease, buffing compounds and dirt by a suitable cleaner such as a vapor degreaser containing trichlorethylene or perchlorethylene. For further removal of any light residual films remaining after vapor degreasing, a mild alkaline cleaner may be used.
  • a suitable cleaner such as a vapor degreaser containing trichlorethylene or perchlorethylene.
  • a suitable cleaner of this general type can be prepared by using 4 ounces of sodium carbonate and 4 ounces of sodium phosphate per gallon of water. This solution is generally used at a temperature of to F. for about 1 to 3 minutes. It should be noted however, that mild alkaline cleaners which function without etching, are not efiective in removing the oxide coating on aluminum surfaces and for this purpose the surface to be cleaned is then subjected to a further treatment in the deoxidizing solution of this invention.
  • the aluminum or aluminum alloy piece is immersed in the deoxidizing solution for a period of anywhere from 5 seconds to 5 minutes depending on the thickness of the surface film and previous treatment.
  • the surface thus produced is rather bright and uniform in appearance and not pitted.
  • the deoxidizing solution of the present invention has been found extremely useful in preparing aluminum and its alloys for spot welding.
  • successful spot welding of aluminum depends upon obtaining a low electrical surface resistance, usually less than 100 microhms for the mating surfaces, and maintaining this low resistance until such time as the parts are welded.
  • test strips of aluminum and several of its alloys were immersed in the hereinabove set forth preferred deoxidizing solution at temperatures ranging from 60 to 95 F. and for periods of time ranging from 2 seconds to 5 minutes, after which the strips were removed from the solution, thoroughly rinsed in water and dried.
  • the surface resistanceof these test strips was then measured by means of an electrical resistance measuring device of the Kelvin Bridge type, and by plotting resistance readings against time of immersion, it was noted that a rapid 5 decrease in surface resistance occurs and that a minimum surface resistance is obtained for an immersion time of approximately 5 to seconds.
  • the plotted curve also indicated that for longer immersion times, the surface i resistance increases and becomes greater than 100 microhms for immersion times greater than approximately seconds.
  • deoxidizing solutions were obtained by which the surface resistance remained below 100 microhms for immersion periods substantially in excess of 20 seconds.
  • the immersion time which produced a low resistance surface having the greatest stability or i so-called shelf life for 24S clad aluminum was determined l to be 10 seconds. This low surface resistance, of less than 10 microhms, was maintained for approximately 2 days and after 30 days was only 30 microhms.
  • the copper was intr uce 1n e orm of a so u e sa i such as copper oxide which is compatible with the solution such that the anion will not form precipitates with other solution constituents.
  • the presence of copper ions in the deoxidizing solution may be as much as 1' that obtained with 1 gram of copper oxide per liter of solution, although the preferred concentration is that obtained 2 with approximately 0.3 gram per liter.
  • Excellent results were also obtained with the addition of other metals selected from the group consisting of iron, zinc, magnesium and manganese which were introduced into the solution in quantities similar to that of the copper and in the form of zinc oxide, magnesium oxide and potassium permanganate. It is believed that these added metals plate by immersion on the aluminum and aluminum alloy surfaces to thereby form a protective film which acts as an oxidation inhibitor without affecting the surface resistance.
  • the process of treating aluminum and its alloys which comprises immersing the metal in an aqueous solution containing 8 to 98% nitric acid (70% concentrate) and containing fluoride and chromate ions in concentrations corresponding to that obtained in a solution containing 1 to 45 grams of sodium fluoride per liter of solution and 1 to 400 grams of anhydrous chromic acid per liter of solution for a time suflicient to initially reduce the surface resistance of the metal to below 100 microhms, removing the metal from said aqueous solution before the surface resistance again reaches 100 microhms and thereafter rinsing the thus treated metal.
  • aqueous solution contains copper ions in concentrations corresponding to that obtained in a solution containing up to 1 gram of copper oxide per liter of solution.
  • An aqueous deoxidizing solution consisting of 8 to 98% nitric acid concentrate), fluoride and chromate ions in concentrations corresponding to that obtained in a solution containing 1 to 45 grams of sodium fluoride per liter of solution and 1 to 400 grams of anhydrous chromic acid per liter of solution, and copper ions in concentrations corresponding to that obtained in a solution containing up to 1 gram of copper oxide per liter of solution.
  • An aqueous deoxidizing solution consisting of 8 to 98% nitric acid (70% concentrate), fluoride and chromate ions in concentrations corresponding to that obtained in a solution containing 1 to 45 grams of sodium fluoride per liter of solution and 1 to 400 grams of anhydrous chromic acid per liter of solution, and metal ions selected from the group consisting of copper, iron, zinc, magnesium and manganese.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
  • Chemical Treatment Of Metals (AREA)

Description

2,883,311 lc Patented AIM- 1959 METHOD AND COMPOSITION FOR TREATING ALUMINUM AND ALUMINUM ALLOYS David Halpert, Philadelphia, Pa., assignor to Vertol Aircraft Corporation, Morton, Pa., a corporation of Pennsylvania No Drawing. Application October 1, 1956 Serial No. 614,779
6 Claims. (Cl. 134-3) This invention relates to the surface treatment of aluminum and aluminum base alloys for the removal of oxide films, and more particularly to the composition and method for treating aluminum surfaces so as to maintain a low electrical resistance for a substantial period of time.
Surface cleaning of aluminum and it alloys, for producing and maintaining a smut-free bright surface, is made diflicult by the rapid formation of oxide coatings on aluminum when exposed to the atmosphere. It is essential that the deoxidizing solution dissolve away the natural oxide film without attacking the aluminum metal too sharply, which would result in etching or pitting of the surface. This can be done if a uniform reaction takes place between the aluminum and the deoxidizing solution such that the solution acts on all parts of the surface simultaneously and with the same reaction speed.
It is therefore, a primary object of this invention to provide a chemical deoxidizing solution for removing the oxide coatings on aluminum and its alloys wherein the composition agents are readily controllable at the room operating temperature of the solution, and further, wherein the dimensional tolerance losses of the aluminum are positively controlled by the use of an inhibitor.
A further object of the invention is to provide an aluminum deoxidizing solution comprising an aqueous acid solution containing fluorides, chromates or dichromates and nitric acid in certain well defined proportions and ranges of concentration for producing an electrically low resistant surface without excessively removing the aluminum base metal.
Further objects and advantages of the chemical deoxidizing solution will become apparent from the follow ing description.
The term deoxidizing solution is used throughout the description in place of chemical cleaning solution because it more accurately defines the function of the solution, which is to remove the characteristic oxide coating on aluminum and its alloys.
In general, the composition of the deoxidizing solution consists of relatively high concentrations of nitric acid and fluorides in combination with hexavalent chromium ions. Nitric acid (70% concentrate) is preferably used in an amount within the range of from about 80 to 90 cc. per liter. The fluoride constituent may be introduced in the form of a simple or complex fluoride which is soluble in nitric acid without producing objectionable precipitates with the chromium ions or the aluminum ions that may find their way into the solution by metal dissolution. Sodium fluoride is preferably used for supplying the fluoride ion since it is easily handled and relatively eco nomical. It has been found that the fluoride ion concentration of the deoxidizing solution should be maintained at an amount approximately equivalent to that obtained with l to 45 grams of sodium fluoride per liter of solution. Also, by varying the amount of sodium fluoride introduced into solution, it is possible to control the solution pH value, which for best results should be maintained within a range of 0.2 to 1.7, the preferred pH range being 0.35 to 0.9.
Chromic acid is a preferred constituent for supplying the hexavalent chromium ion which acts as the inhibitor for the otherwise vigorously reacting mixture of fluorides and nitric acid. The hexavalent chromium ion when properly proportioned with the fluoride ion and the nitric acid, tends to regulate the dissolving action of the deoxidizing solution on the aluminum such that its dimensional losses do not exceed 0.0002" even for an immersion time of approximately 5 minutes in a 60 to 95 F. solution. It was found that the chromium ion concentration should be maintained in an amount approximately equivalent to that obtained with 1 to 400 grams of anhydrous chromic acid per liter of solution.
Thus, the deoxidizing solution of the present invention essentially comprises:
Proper Constituent tlon Preferred Range Nitric Acid-BNO; (70% concentrate). -cc./l. 80 to 980 330 Sodium Fluoride-Nah (anhydrous) g./l 1 to 45 15 Chromic Acid-CrO; (anhydrous).. /l. 1 to 400 l5 2 WaterH 0 Balance Balance Prior to the immersion of the aluminum or its alloy in the deoxidizing solution, the surface is preferably cleaned of heavy oil, grease, buffing compounds and dirt by a suitable cleaner such as a vapor degreaser containing trichlorethylene or perchlorethylene. For further removal of any light residual films remaining after vapor degreasing, a mild alkaline cleaner may be used. Though a number of commercial cleaners of this type are available, a suitable cleaner of this general type can be prepared by using 4 ounces of sodium carbonate and 4 ounces of sodium phosphate per gallon of water. This solution is generally used at a temperature of to F. for about 1 to 3 minutes. It should be noted however, that mild alkaline cleaners which function without etching, are not efiective in removing the oxide coating on aluminum surfaces and for this purpose the surface to be cleaned is then subjected to a further treatment in the deoxidizing solution of this invention.
When it is desired to prepare the surface for the application of protective or decorative coatings such as those obtained by anodizing or chromatizing or to prepare the surface for the plating thereon of metallic coatings, the aluminum or aluminum alloy piece is immersed in the deoxidizing solution for a period of anywhere from 5 seconds to 5 minutes depending on the thickness of the surface film and previous treatment. The surface thus produced is rather bright and uniform in appearance and not pitted.
The deoxidizing solution of the present invention has been found extremely useful in preparing aluminum and its alloys for spot welding. In this connection, it should be noted that successful spot welding of aluminum depends upon obtaining a low electrical surface resistance, usually less than 100 microhms for the mating surfaces, and maintaining this low resistance until such time as the parts are welded. In order to determine the immersion time required to produce a low electrical surface resistance, test strips of aluminum and several of its alloys were immersed in the hereinabove set forth preferred deoxidizing solution at temperatures ranging from 60 to 95 F. and for periods of time ranging from 2 seconds to 5 minutes, after which the strips were removed from the solution, thoroughly rinsed in water and dried. The surface resistanceof these test strips was then measured by means of an electrical resistance measuring device of the Kelvin Bridge type, and by plotting resistance readings against time of immersion, it was noted that a rapid 5 decrease in surface resistance occurs and that a minimum surface resistance is obtained for an immersion time of approximately 5 to seconds. The plotted curve also indicated that for longer immersion times, the surface i resistance increases and becomes greater than 100 microhms for immersion times greater than approximately seconds. However, by varying the proportions of the constituents within the disclosed ranges, deoxidizing solutions were obtained by which the surface resistance remained below 100 microhms for immersion periods substantially in excess of 20 seconds.
It was found that the lower the resistance obtained as the result of a 5 to 10 second immersion, the more stable the deoxidized surface was in maintaining its low resistj ance. For example, the immersion time which produced a low resistance surface having the greatest stability or i so-called shelf life for 24S clad aluminum, was determined l to be 10 seconds. This low surface resistance, of less than 10 microhms, was maintained for approximately 2 days and after 30 days was only 30 microhms.
It was also found that electrically low resistance surfaces could be obtained and maintained for prolonged periods by using the hereinabove set forth deoxidizing solution with small amounts of copper dissolved therein.
; The copper was intr uce 1n e orm of a so u e sa i such as copper oxide which is compatible with the solution such that the anion will not form precipitates with other solution constituents. The presence of copper ions in the deoxidizing solution may be as much as 1' that obtained with 1 gram of copper oxide per liter of solution, although the preferred concentration is that obtained 2 with approximately 0.3 gram per liter. Excellent results were also obtained with the addition of other metals selected from the group consisting of iron, zinc, magnesium and manganese which were introduced into the solution in quantities similar to that of the copper and in the form of zinc oxide, magnesium oxide and potassium permanganate. It is believed that these added metals plate by immersion on the aluminum and aluminum alloy surfaces to thereby form a protective film which acts as an oxidation inhibitor without affecting the surface resistance.
Having thus described my invention, what I claim is:
l. The process of treating aluminum and its alloys which comprises immersing the metal in an aqueous solution containing 8 to 98% nitric acid (70% concentrate) and containing fluoride and chromate ions in concentrations corresponding to that obtained in a solution containing 1 to 45 grams of sodium fluoride per liter of solution and 1 to 400 grams of anhydrous chromic acid per liter of solution for a time suflicient to initially reduce the surface resistance of the metal to below 100 microhms, removing the metal from said aqueous solution before the surface resistance again reaches 100 microhms and thereafter rinsing the thus treated metal.
2. A process according to claim 1 in which the aqueous solution contains copper ions in concentrations corresponding to that obtained in a solution containing up to 1 gram of copper oxide per liter of solution.
3. A process according to claim 1 in which the aqueous solution contains metals selected from the group consisting of copper, iron, zinc, magnesuim and manganese.
4. An aqueous deoxidizing solution consisting of 8 to 98% nitric acid concentrate), fluoride and chromate ions in concentrations corresponding to that obtained in a solution containing 1 to 45 grams of sodium fluoride per liter of solution and 1 to 400 grams of anhydrous chromic acid per liter of solution, and copper ions in concentrations corresponding to that obtained in a solution containing up to 1 gram of copper oxide per liter of solution.
5. An aqueous deoxidizing solution consisting of 8 to 98% nitric acid (70% concentrate), fluoride and chromate ions in concentrations corresponding to that obtained in a solution containing 1 to 45 grams of sodium fluoride per liter of solution and 1 to 400 grams of anhydrous chromic acid per liter of solution, and metal ions selected from the group consisting of copper, iron, zinc, magnesium and manganese.
6. The process of treating aluminum and its alloys which comprises immersing the metal in an aqueous solution consisting of 8 to 98% nitric acid (70% concentrate) and fluoride and chromate ions in concentrations corresponding to that obtained in a solution containing 1 to 45 grams of sodium fluoride per liter of solution and l to 400 grams of anhydrous chromic acid per liter of solution for 5 to 20 seconds, removing the metal from said aqueous solution and thereafter rinsing the thus treated metal.
References Cited in the file of this patent UNITED STATES PATENTS 2,428,749 De Long Oct. 7, 1947 2,598,889 Caugherty June 3, 1952 2,705,500 Deer Apr. 5, 1955 FOREIGN PATENTS 726,660 Great Britain Mar. 23, 1955

Claims (1)

1. THE PROCESS OF TREATING ALUMINUM AND ITS ALLOYS WHICH COMPRISES IMMERSING THE METAL IN AN AQUEOUS SOLUTION CONTAINING 8 TO 98% NITRIC ACID (70% CONCENTRATE) AND CONTAINING FLUORIDE AND CHROMATE IONS IN CONCENTRATIONS CORRESPONDING TO THAT OBTAINED IN A SOLUTION CONTAINING 1 TO 45 GRAMS OF SODIUM FLUORIDE PER LITER OF SOLUTION AND 1 TO 400 GRAMS OF ANHYDROUS CHROMIC ACID PER LITER OF SOLUTION FOR A TIME SUFFICIENT TO INITIALLY REDUCE THE SURFACE REISITANCE OF THE METAL TO BELOW 100 MICROHMS, REMOVING THE METAL FROM SAID AQUEOUS SOLUTION BEFORE THE SURFACE RESISTANCE AGAIN REACHES 100 MICROHMS AND THEREAFTER RINSING THE THUS TREATED METAL.
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Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2977204A (en) * 1959-08-14 1961-03-28 Donald W Shannon Method of improving corrosion resistance of zirconium
US2996353A (en) * 1959-04-01 1961-08-15 Du Pont Sodium fluochromate and the process for preparing the same
US3011923A (en) * 1960-02-19 1961-12-05 Charles O Coffer Surface treatment of molybdenum metal
US3074824A (en) * 1962-03-16 1963-01-22 Aluminum Co Of America Removing flux residues
US3197340A (en) * 1960-10-05 1965-07-27 Conversion Chem Corp Composition and method for cleaning aluminum castings
US3280038A (en) * 1964-03-20 1966-10-18 Dow Chemical Co Method for cleaning stainless steel
US3336163A (en) * 1963-09-24 1967-08-15 Olin Mathieson Process for activating aluminum anode
US4087367A (en) * 1974-10-18 1978-05-02 U.S. Philips Corporation Preferential etchant for aluminium oxide
US4273679A (en) * 1978-06-03 1981-06-16 Chinoin Gyogyszer Es Vegyeszeti Termekek Gyara Rt. Aluminum alloys having a high reducing capacity and preparation thereof
US4451304A (en) * 1981-05-04 1984-05-29 Walter Batiuk Method of improving the corrosion resistance of chemical conversion coated aluminum
US4504324A (en) * 1983-11-07 1985-03-12 Nippon Paint Co., Ltd. Surface treatment of aluminum materials
US4711667A (en) * 1986-08-29 1987-12-08 Sanchem, Inc. Corrosion resistant aluminum coating
US4851077A (en) * 1988-05-19 1989-07-25 Mcdonnell Douglas Corporation Chemical milling of lithium aluminum alloy
US4895608A (en) * 1988-04-29 1990-01-23 Sanchem, Inc. Corrosion resistant aluminum coating composition
US5052421A (en) * 1988-07-19 1991-10-01 Henkel Corporation Treatment of aluminum with non-chrome cleaner/deoxidizer system followed by conversion coating
US5707465A (en) * 1996-10-24 1998-01-13 Sanchem, Inc. Low temperature corrosion resistant aluminum and aluminum coating composition
US20090220816A1 (en) * 2006-06-23 2009-09-03 Nissan Motor Co., Ltd Metal base, method for producing the same, and catalyst

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2428749A (en) * 1944-08-19 1947-10-07 Dow Chemical Co Surface treatment of magnesium alloys
US2598889A (en) * 1947-07-18 1952-06-03 Allegheny Ludlum Steel Pickling chromium alloys
GB726660A (en) * 1950-10-20 1955-03-23 Gen Motors Corp Improvements in solutions for treating metallic surfaces
US2705500A (en) * 1953-11-04 1955-04-05 Leon L Deer Cleaning aluminum

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2428749A (en) * 1944-08-19 1947-10-07 Dow Chemical Co Surface treatment of magnesium alloys
US2598889A (en) * 1947-07-18 1952-06-03 Allegheny Ludlum Steel Pickling chromium alloys
GB726660A (en) * 1950-10-20 1955-03-23 Gen Motors Corp Improvements in solutions for treating metallic surfaces
US2705500A (en) * 1953-11-04 1955-04-05 Leon L Deer Cleaning aluminum

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2996353A (en) * 1959-04-01 1961-08-15 Du Pont Sodium fluochromate and the process for preparing the same
US2977204A (en) * 1959-08-14 1961-03-28 Donald W Shannon Method of improving corrosion resistance of zirconium
US3011923A (en) * 1960-02-19 1961-12-05 Charles O Coffer Surface treatment of molybdenum metal
US3197340A (en) * 1960-10-05 1965-07-27 Conversion Chem Corp Composition and method for cleaning aluminum castings
US3074824A (en) * 1962-03-16 1963-01-22 Aluminum Co Of America Removing flux residues
US3336163A (en) * 1963-09-24 1967-08-15 Olin Mathieson Process for activating aluminum anode
US3280038A (en) * 1964-03-20 1966-10-18 Dow Chemical Co Method for cleaning stainless steel
US4087367A (en) * 1974-10-18 1978-05-02 U.S. Philips Corporation Preferential etchant for aluminium oxide
US4273679A (en) * 1978-06-03 1981-06-16 Chinoin Gyogyszer Es Vegyeszeti Termekek Gyara Rt. Aluminum alloys having a high reducing capacity and preparation thereof
US4451304A (en) * 1981-05-04 1984-05-29 Walter Batiuk Method of improving the corrosion resistance of chemical conversion coated aluminum
US4504324A (en) * 1983-11-07 1985-03-12 Nippon Paint Co., Ltd. Surface treatment of aluminum materials
US4711667A (en) * 1986-08-29 1987-12-08 Sanchem, Inc. Corrosion resistant aluminum coating
US4895608A (en) * 1988-04-29 1990-01-23 Sanchem, Inc. Corrosion resistant aluminum coating composition
US4851077A (en) * 1988-05-19 1989-07-25 Mcdonnell Douglas Corporation Chemical milling of lithium aluminum alloy
US5052421A (en) * 1988-07-19 1991-10-01 Henkel Corporation Treatment of aluminum with non-chrome cleaner/deoxidizer system followed by conversion coating
US5707465A (en) * 1996-10-24 1998-01-13 Sanchem, Inc. Low temperature corrosion resistant aluminum and aluminum coating composition
US20090220816A1 (en) * 2006-06-23 2009-09-03 Nissan Motor Co., Ltd Metal base, method for producing the same, and catalyst

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