Nickel-free metal phosphating composition and method for use
AssigneeAmchem Products, Inc.
InventorsMark B. Knaster, William R. Skowronek
Life of this patent
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Abstract
Nickel-free aqueous phosphating compositions containing zinc ions, cobalt ions, phosphate ions, and at least two additional cations; methods for using such composition, and products of the methods.
Claims34
A nickel-free aqueous solution for depositing a phosphate coating on a substrate of one or more metals simultaneously comprising the following, each present in a phosphating-effecting amount:
- (A) phosphate anions;
- (B) zinc cations;
- (C) cobalt cations;
- (D) at least one buffer capable of, and present in an amount sufficient to, maintain the solution pH at about 2.8 to 3.2;
- and
- (E) two or more of the group comprising:
- Al.sup.+++, Ba.sup.++, Ca.sup.++, Mg.sup.++, Mn.sup.++, and Sr.sup.++.
The solution of claim wherein said zinc cations are present in about 0.6 to 1.6 g/l.
A nickel-free aqueous solution for depositing a phosphate coating on a substrate of one or more metals simultaneously comprising;
- (A) phosphate ions,
- (B) zinc ions,
- (C) cobalt ions,
- (D) at least one buffer capable of maintaining the pH of the solution at about 2.8 to 3.2, and
- (E) at least two additional cations other than nickel or those above, present in an amount effective to reduce the redox potential differential when more than one substrate is present, to less than about 0.35 volts between said substrates.
A nickel-free aqueous solution for depositing a phosphate coating. on a substrate having different electrochemical surface characteristics comprising:
- (A) phosphate ions,
- (B) zinc ions,
- (C) cobalt ions,
- (D) at least one buffer capable of maintaining the pH of said solution at about 2.8 to about 3.2, and
- (E) at least two additional cations other than nickel or those above, present in an amount effective to reduce the redox potential differential of said substrate to less than about 0.35 volts.
A method for depositing a phosphate coating on a substrate having different electrochemical surface characteristics comprising contacting said substrate with a nickel-free aqueous solution comprising;
- (A) phosphate ions,
- (B) zinc ions,
- (C) cobalt ions,
- (D) at least one buffer capable of maintaining the pH of said solution at about 2.8 to about 3.2, and
- (E) at least two additional cations other than nickel or those above, present in an amount effective to reduce the redox potential differential of said substrate to less than about 0.35 volts.
A method for providing a corrosion-inhibiting coating on a substrate having different electrochemical surface characteristics comprising contacting said substrate with a nickel-free aqueous solution comprising:
- (A) phosphate ions,
- (B) zinc ions,
- (C) cobalt ions,
- (D) at least one buffer capable of maintaining the pH of said solution at about 2.8 to about 3.2, and
- (E) at least two additional cations other than nickel or those above, present in an amount effective to reduce the redox potential differential of said substrate to less than about 0.35 volts.
A method for providing corrosion-inhibiting coatings on first and second substrates, each having different electrochemical surface characterisics, and each in intimate contact with each other, comprising simultaneously contacting said first substrate and said second substrate with a nickel-free aqueous solution comprising:
- (A) phosphate ions,
- (B) zinc ions,
- (C) cobalt ions,
- (D) at least one buffer capable of maintaining the pH of said solution at about 2.8 to about 3.2, and
- (E) at least two additional cations other than nickel or those above, present in an amount effective to reduce the redox potential differential of said substrates to less than about 0.35 volts.
Dependencies are inferred from the claim text.