Corrosion inhibition treatments and method
First Claim
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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Abstract
The invention deals with a method and composition(s) for use in inhibiting corrosion of metallic parts in contact with aqueous systems. It has been discovered that protective oxide films can be formed on the metallic surface if such is allowed to contact an aqueous system containing a sufficient amount for the purpose of a polymer composed primarily of acrylic moieties and hydroxylated lower alkyl acrylate moieties and a water-soluble orthophosphate. Optionally but desirably, polyphosphates, organo-phosphonates, and copper corrosion inhibitors may be included.
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Citations
46 Claims
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. 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 have the following formulas;
##STR15## 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; and (c) a water-soluble polyphosphate 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), (b) and (c) being added being sufficient to provide a substantially scale-free protective passive oxide film on the metallic surface. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31)
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32. A composition for providing a protective passive oxide film on the surface of a ferrous metallic part in contact with an aqueous solution with little or no attendant deposition of scale on said part, which comprises
(i) a water-soluble polymer consisting essentially of 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 have the following formulas: - ##STR16## 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(ii) a water-soluble orthophosphate compound, the ratio on a weight basis of the polymer to the orthophosphate expressed as PO4--- being from about 1;
8 to about 4;
1. - View Dependent Claims (33, 34, 35, 36, 37, 38)
- ##STR16## wherein R is hydrogen or a lower alkyl of from 1 to 3 carbon atoms;
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39. A composition for providing a protective passive oxide film on the surface of a metallic part in contact with an aqueous solution with little or no attendant deposition of scale on said part, which comprises
(i) a water-soluble polymer consisting essentially of 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 have the following formulas: - ##STR17## 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;(ii) a water-soluble orthophosphate compound, the ratio on a weight basis of the polymer to the orthophosphate expressed as PO4--- being from about 1;
8 to about 4;
1, and(iii) a water-soluble polyphosphate compound, the ratio of orthophosphate to polyphosphate both expressed as PO4--- being about 15;
1 to about 1;
3. - View Dependent Claims (40, 41, 42, 43, 44, 45, 46)
- ##STR17## wherein R is hydrogen or a lower alkyl of from 1 to 3 carbon atoms;
Specification