Multi-layer multi-metal electroplated protective coating

• US 4,418,125 A
• Filed: 12/06/1982
• Issued: 11/29/1983
• Est. Priority Date: 12/06/1982
• Status: Expired due to Fees

• Current Assignee: Geraldine W., Named Executor Henricks
• Original Assignee: John A. Henricks
• Inventors: Henricks, John A.
• Primary Examiner(s): Kaplan, G. L.
• Application Number:
  US06/432,562
• Time in Patent Office: 358 Days
• Field of Search: 204/41, 204/40, 428/639, 428/657, 428/667, 428/674, 428/675, 428/679
• US Class Current: 428/639
• CPC Class Codes: C25D 5/14 two or more layers being of nickel or chromium, e.g. duplex or triplex layers
• CPC Class Codes: C25D 5/611 Smooth layers
• CPC Class Codes: C25D 5/623 Porosity of the layers
• CPC Class Codes: C25D 5/627 Electroplating characterised by the visual appearance of the layers, e.g. colour, brightness or mat appearance
• CPC Class Codes: Y10T 428/1266 O, S, or organic compound in metal component
• CPC Class Codes: Y10T 428/12785 Group IIB metal-base component
• CPC Class Codes: Y10T 428/12854 Next to Co-, Fe-, or Ni-base component
• CPC Class Codes: Y10T 428/12903 Cu-base component
• CPC Class Codes: Y10T 428/1291 Next to Co-, Cu-, or Ni-base component
• CPC Class Codes: Y10T 428/12937 Co- or Ni-base component next to Fe-base component

Abstract

This invention is directed to the formation of highly protective electroplated multi-metal coatings over an iron basis metal. The high degree of protection is obtained by the deposition of three sucessive layers of two dissimilar metal layers that form a galvanic cell in which one of the two adjacent metals is anodic to the other so that the corroding anodic electroplate will spread the attack laterally and thus prevent the corrosive media from drilling through to the base metal. The coating comprises an initial layer of sulfur free nickel followed in sucession by a sulfur containing bright nickel, cadmium, copper, sulfur free nickel, sulfur containing nickel and microporous chromium.

Claims

1. A method of electroplating a composite protective coating for steel which comprises electroplating on said steel an initial layer of about 0.00015" of sulfur free nickel, followed by about 0.00015" of sulfur containing bright nickel and followed in sucession by about 0.0002" of cadmium and by about 0.0002" of copper which is then coated with a second layer of about 0.00015" of sulfur free nickel and a second layer of about 0.00015" of sulfur containing bright nickel, after which the bright nickel is electroplated with about 0.00001" of microporous chromium.

2. A steel article coated with the composite multi-layer multi-metal coating of claim 1.