Threaded fasteners used in corrosive environments are plated with electroless nickel and electroplated, over the nickel, with tin. This provides a corrosion-resistant coating for the fasteners

Charles, J.

Veeder, L.

English

NASA Technical Reports Server

December 1965	 Brief 65-10398 
NASA TECH BRIEF H 
NASA Tech Briefs are issued by the Technology Utilization Division to summarize specific 
technical innovations derived from the space program. Copies are available to the public from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia, 22151. 
Nickel/Tin Coating Protects Threaded Fasteners in Corrosive Environment 
The problem: To provide an adequate corrosion-
resistant coating for threaded fasteners used in cor-
rosive environments. Cadmium and zinc have posed 
plating thickness control problems on complex sur-
faces such as threads and recessed socket heads. 
The solution: A process by which parts are plated 
with 0.0001 to 0.0002 inch of electroless nickel and 
electroplating, over the nickel, 0.0001 to 0.0002 
inch of tin. 
How it's done: The electroless nickel is deposited 
by a conventional electroless nickel bath employing 
constant filtration. The tin is deposited from a bath 
containing 14 oz/gallon of potassium stannate and 
2 oz/gallon of free potassium hydroxide. However, 
any electrodeposited tin such as from a fluoroborate 
or sulfuric acid bath, should produce an equivalent 
coating if thermally diffused. The use of diffusion is 
governed by the temperature of the corrosive environ-
ment to which the part is to be exposed. Diffusion 
is accomplished by heating the electroless nickel-
coated workpiece to 485±10°F for two hours.
Notes: 
I. Alloy steel fasteners treated with this coating have 
withstood 96 hoursof salt spray without corrosive 
damage. 
Inquiries concerning this invention may be di-
rected to: 
Technology Utilization Officer 
Manned Spacecraft Center 
P.O. Box 1537 
Houston, Texas, 77001 
Reference: B65-10398 
Patent status: NASA encourages the immediate 
commercial use of this invention. Inquiries about ob-
taining rights for its commercial use may be made to 
NASA, Code AGP, Washington, D.C., 20546. 
Source: James Charles and Lloyd Veeder 
of North American Aviation, Inc., 
under contract to 
Manned Spacecraft Center 
(MSC-253) 
Category 03 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
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Nickel/tin coating protects threaded fasteners in corrosive environment

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