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
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C22/78—Pretreatment of the material to be coated

Definitions

• This invention relates to the preparation of surfaces for coating and more particularly 7 for coating with a layer of insoluble phos phatesformed in situ.
• the invention consists in the electrolytic deposition of iron on a surface, and the subjection of the surface thus produced to a dilute solution of phosphates until a coating of insoluble phosphates is produced thereon;
• the electrolytic deposition of iron may be accomplished in any well "known manner.
• the article to be coated may be used as the cathode in a solution of ferrous ammonium sulphate.
• a saturated solution isused, which contains about three pounds of the sulphate to one gallon of water.
• the efficiency of the solution may be increased by the use of other salts to reduce the resistance of the bath.
• One mixture found suit-able is as follows:
• equal volumes of solutions A, B, C and D are mixed together in an iron container which serves as an anode and the article to be coated is dipped in the solution and used as a cathode.
• the current is kept at approximately 6 :volts and at a current density often to twelve amperes per square foot of the surface of the object to be coated.
• This phosphate bath maybe prepared in any of the ways well known to the art and need not be specifically described here.
• the advantage of the electrolytically deposited iron coating on an iron or steel article flows from the more prompt reaction of the electrolytically deposited iron. This makes possible a greater production with the same equipment and results in a more even and satisfactory coating. there is some wasteful hydrolytic dissociation resulting in the forming of sludge in the phosphate bath, aside from the reactions involved in the actual rust-proofing, and therefore the lessening of the time of reaction not only results in more production for the same amount of equipment and a more satisfactory coating on the articles, but also reduces the relative amount of waste in the bath.
• the insoluble phosphate coating referred to above forms a very good surface for receiving paint, varnish, lacquer or enamel.
• Aluminum and zinc may be mentioned as common materials whose regular surface is not good for retaining paint or similar coatings, but which may be quickly and effectivel Y repared for painting by the above described method.
• the electrolytical y deposited iron may be utilized for initiating the deposition o the phosphate coating and the formation of this coating may be continued with the metal of the body of the article, and this is true of other metals such as zinc, manganese and magnesium, which will react with the bath to form insoluble phosphates.
• the treatment with the phosphate bath may be stopped short of the transformation of all of the electrolytically deposited iron into phosphates.
• the electrolytically deposited iron reacts in the phosphate bath more promptly than any other material which I havejound, it is preferable to deposit substantially enough of this iron to carry out the reaction.
• any of the electrolytically deposited iron is not acted upon by the phosphate bath, it constitutes a layer of material with different electrical characteristics and thereby increases galvanic action and liability to rusting. For this reason it is preferable to deposit substantially as much iron as will react in the phosphate bath and to continue the treatment in the phosphate bath until reaction with substantially all of the iron thus deposited has been completed.
• Zinc, magnesium or manganese may be electrolytically deposited instead of iron, and form the coating which reacts with the phosphate solution to form a coating of insoluble phosphates; but iron reacts more promptly than zinc or magnesium, and is readily deposited electrolytically, and therefore is considered the best metal to use.
• the method which consists in electrolytically depositing a coating of iron upon the surface of an article and treating the iron thus deposited with a solution of phosphates until a coating of insoluble hosphates is formed upon the surface 0 article.
• the method which consists in electrolytically depositing upon the surface of an article a coating of Illt' i, treating the iron with a solution of phosphates until there is formed a coating of insoluble phosphates, and applying to the surface thus formed an adherent air-proof coating.
• the method which consists in electrolytically depositing upon the surface of an article a coating of a. metal capable of reacting with a hosphate solution to form a coating of inso uble phosphates, and treating the coated article with a phosphate solution until substantially all of the electrolytically deposited metal has reacted with the solution.
• the method of coating a surface of aluminum which consists in electrolytically depositing thereon a coating of iron and treating the iron coating with a dilute phosphate bath until substantially all of the iron has reacted to form plies hates.

Landscapes

• Chemical & Material Sciences (AREA)
• General Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Chemical Treatment Of Metals (AREA)

Priority Applications (3)

Applications Claiming Priority (1)

Publications (1)

Family

ID=23231115

Family Applications (1)

Country Status (3)

Cited By (2)

Families Citing this family (1)

• 1928
  • 1928-11-02 US US316883A patent/US1860505A/en not_active Expired - Lifetime
• 1929
  • 1929-10-18 FR FR683486D patent/FR683486A/fr not_active Expired
  • 1929-10-26 DE DEM112369D patent/DE562561C/de not_active Expired

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