Calcium fluoride-barium fluoride coating on ball bearing cages or as fillers in porous bearing cages lubricate bearings successfully for operations in air at temperatures of 1200 to 1500 degrees F

Johnson, R. L.

Sliney, H. E.

English

NASA Technical Reports Server

February 1969	 Brief 69-10025 
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. 
Evaluation of Lubricants for Ball Bearings at High Temperatures 
Ball bearings fabricated from high-temperature 
alloys (Stellite 6B balls and races and Reñe 41 cages) 
were operated in air at temperatures up to 15001F. 
The adherent oxides which formed on these alloys 
prevented bearing seizure and high wear on otherwise 
unlubricated bearings. However, bearing torque was 
high and erratic. 
In previous basic studies of high temperature lubri-
cants, new solid lubricants which had low friction 
coefficients and effective antiwear characteristics at 
elevated temperatures (1000 1 -1900°F) were formu-
lated. 
A test program was therefore begun to determine 
the feasibility of lubricating ball bearings with the 
solid lubricants which had appeared promising in the 
basic studies. 
The solid lubricants were calcium fluoride—barium 
fluoride coatings which were applied to the bearing 
cages, or, in some cases, the cages were fabricated 
from self-lubricating composites consisting of porous, 
sintered nickel—chromium alloy impregnated with a 
calcium fluoride—barium fluoride eutectic filler. All 
tests were conducted in air. 
The bearings (20-mm bore) were of the angular con-
tact type. Under a 30-pound thrust load, which pro-
duced a Hertz stress of 93,000 psi at 1200 0 F, fluo- 
ride-lubricated bearings ran at 5000 rpm without fail-
ing for as long as 700 hours at 1200 1 F and 70 hours 
at 1500°F. The shortest lives under these condi-
tions were of the order of 20 to 50 hours. Wear rates 
were very low until just prior to the onset of bear-
ing failure. 
Notes: 
I. The tests demonstrated that calcium fluoride-
barium fluoride as coatings on bearing cages or as 
fillers in porous bearing cages could lubricate 
bearings successfully for operations in air at tem-
peratures of 1200° to 1500° F. 
2. Documentation is available from: 
Clearinghouse for Federal Scientific 
and Technical Information 
Springfield, Virginia 22151 
Price $3.00 
Reference: B69-10025 
3. Technical questions may be directed to: 
Technology Utilization Officer 
Lewis Research Center 
21000 Brookpark Road 
Cleveland, Ohio 44135 
Patent status: 
No patent action is contemplated by NASA. 
Source: H. E. Sliney and R. L. Johnson 
(LEW- 10578) 
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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Evaluation of lubricants for ball bearings at high temperatures

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