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Corrosion inhibition treatments and method

  • US 4,303,568 A
  • Filed: 12/10/1979
  • Issued: 12/01/1981
  • Est. Priority Date: 12/10/1979
  • Status: Expired due to Term
First Claim
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1. A method of inhibiting the corrosion of ferrous metal parts in contact with an aqueous solution with little or no attendant deposition of scale on said ferrous parts, which corrosion inhibition is obtained by providing for the formation of a protective passive oxide film on the metal surface in contact with said aqueous medium, which method comprises(i) assuring that the pH of said aqueous medium is 5.5 or above;

  • (ii) assuring that the aqueous medium contains a calcium or other appropriate ion concentration selected from the group consisting of zinc, nickel and chromium and mixtures thereof; and

    (iii) adding to said aqueous medium(a) a water-soluble polymer comprising moieties derived from an acrylic acid or water-soluble salt thereof and moieties of an hydroxylated lower alkyl acrylate, wherein the moieties of the polymer having the following formulas;

    ##STR14## wherein R is hydrogen or a lower alkyl of from 1 to 3 carbon atoms;

    R1 is OH, OM or NH2 where M is a water-soluble cation;

    R2 is a lower alkyl of from about 2 to 6 carbon atoms and the mole ratio of x;

    y is 34;

    1 to 1;

    4; and

    (b) a water-soluble orthophosphate compound;

    said polymer being such that together with the orthophosphate compound is effective to promote the metal oxide film with no attendant deposition, and the amount of (a) and (b) being added being sufficient to provide a substantially scale-free protective passive oxide film on the metallic surface.

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