Self-lubricating composites of porous nickel and nickel-chromium alloy impregnated with a barium fluoride-calcium fluoride eutectic, and a thin film of solid lubricant increase wear life of load bearing surfaces

Sliney, H. E.

English

NASA Technical Reports Server

January 1967	 Brief 67-10007 
NASA TECH BRIEF 
NASA Tech Briefs are issued to summarize specific innovations derived from the U.S. space program, 
to encourage their commercial application. Copies are available to the public at 15 cents each 
from the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Composites of Porous Metal and Solid Lubricants Increase Bearing Life 
The problem: 
Solid lubricants are normally used as coatings or 
dry films bonded to dense metal substrates. In sliding 
contact, lubricant coatings eventually wear through, 
substrate metal contact occurs, and galling plus metal 
transfer results. Although wear life can be extended 
by use of composite bearing materials, those prepared 
by the customary powder metallurgy techniques have 
definite strength limitations. 
The solution: 
Self-lubricating composites of po1'ous nickel and 
nickel—chromium alloy impregnated with a barium 
fluoride—calcium fluoride eutectic, plus an added thin 
film of solid lubricant to the load bearing surfaces 
How it's done: 
Porous nickel specimens of 50% and 60% density, 
having a foam-like structure, are obtained commer-
cially. Porous nickel—chromium alloy specimens are 
prepared by a standard powder metallurgy technique 
from 100-mesh powders. The powders, hydrostatically 
pressed at 20,000 psi and sintered in hydrogen for 
1 hour at 2150°F, produce a porous metal body of 
about 65% density with typical pore diameters of 
25 to 35 microns. 
A porous metal specimen is placed in a metal con-
tainer with an amount of powdered fluoride salt in 
excess of that required to completely fill the voids 
in the porous metal and sufficient to completely cover 
the specimen when the salt melts. The container is 
placed in a chamber that is sealed, evacuated, and
heated to 2,000°F. Capillary action causes the molten 
salt to infiltrate the porous specimen and a slight 
overpressure is used by the introduction of argon or 
nitrogen to assure penetration of the innermost voids. 
After cooling, the specimen is spray coated with 
0.001 inch of fluoride eutectic and sintered in hydro-
gen at 1750° for 10 minutes to establish a good bond 
between specimen and coating. 
Notes: 
I. While higher friction coefficients obtain, compared 
with coatings of the same fluorides on dense 
metals, lower wear characteristics resulting in 
longer wear life make this technique attractive 
for load-bearing sliding surfaces. 
2. Inquiries concerning this invention may . be di-
rected to: 
Technology Utilization Officer 
Lewis Research Center 
21000 Brookpark Road 
Cleveland, Ohio 44135 
Reference: B67-10007 
Patent status: 
This invention is owned by NASA, and a patent 
application has been filed. Royalty-free, non-exclusive 
licenses for its commercial use will be granted by
NASA. Inquiries concerning license rights should be 
made to NASA, Code GP, Washington, D.C. 20546. 
Source: Harold E. Sliney 
(Lewis-307) 
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.
https://ntrs.nasa.gov/search.jsp?R=19670000007 2020-03-11T20:15:34+00:00Z


Composites of porous metal and solid lubricants increase bearing life

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