High temperature gas lubricant consisting of two fluoro-bromo-methane

Buckley, D. H.

Johnson, R. L.

English

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I 
U 
CERTIFICATE OF CORRECTION 
Patent  No. 3,072,574 January 8 ,  1962 
Donald H .  Buckley e t  a l e  
It is hereby ce r t i f i ed  that error  appears i n  the above numbered pat- 
ent req.liring correction and tha t  the said Letters Patent should read as 
coxected below, 
Columns 1 and 2 ,  Table  I ,  under t h e  heading "W" f o r  
"19,O" read -- 5.0  --; same T a b l e  I ,  under t h e  heading "Mo'' 
f o r  rr500~'  read -- 19.0 --- 
Signed  and s e a l e d  t h i s  2 7 t h  day o f  August 1963. 
ERNEST W. SWIDER DAVID L. LADD 
Commissioner of Patents 
https://ntrs.nasa.gov/search.jsp?R=19700030581 2020-03-17T02:15:34+00:00Z
$ . " *  
Hastrlloy C _ _ _ _ _ _ _ _  
Inconel X _ _ _ _ _ _ _ _ _ _  
Stellite 9 8 M L  _ _ _ _  
Rexalloy 33 _ _ _ _ _ _ _ _  
3,072,574 
GAS LUBRICANT C O r ~ O $ ~ ~ ~ ~ $  
cs and Space Adminbtaation 
No Drawing. Filed Oet. 27, 1960, Six. No. 45,548 
6 Claims. (el. 252-58) 
Granted under Title 35, U.S. Code (1952), sec. 246) 
The invention described herein may be manufactured 
and used by or for the Government of the United States 
of America for governmenttal purposes without the pay- 
ment of any royalties thereon or therefor. 
This invention pertains to high temperature gas lubri- 
cants and more particularly to mixtures of halogen-con- 
taining gases. 
Extreme high temperature lubrication is required for 
, advanced types of aerodynamic and space vehicles. For 
example, in missile components such as turbodrives, en- 
vironmental temperatures from 1000" to 1800" F. create 
an important problem area for lubrication. Temperatures 
of this magnitude are beyond the useful limit of conven- 
tional organic liquids and greases and, therefore, uncon- 
ventional methods of lubrication are needed. Halogen- 
substituted methane and similar gases are found to pro- 
vide the necessary lubrication at the extreme high tem- 
peratures. A number of such gaseous compounds possess 
extremely good thermal stability and are capable of 
providing effective lubrication. 
The mechanism for gas lubrication is similar to that 
encountered in extreme pressure lubrication of gears 
where reactive compounds are used as additives to oil. 
The gases employed as lubricants are stable in contact 
with metal surfaces at ambient temperatures. Where 
metals are in sliding contact, however, extremely high 
flash temperatures are generated at contacting metal sur- 
faces; for example, 1100" F. above the ambient tempera- 
ture in effective boundary lubrication. These tempera- 
tures are sufficient to cause localized decomposition of gas 
molecules adsorbed on the metal surface. The halogen 
atoms of the molecule are then free to react with the hot 
metal surface to form metal halides which function as 
solid lubricants. The nature of the metallic halides 
formed on the sliding surface and the rate at which they 
form determine the effectiveness of the lubrication system. 
When the reaotion rate is exceedingly high, an excess 
6.0 
6 t o  9 
3.0 
3.0 
has two forming atoms and provides effective lubrication 
at lower temperatures, that is, below 800" F. At higher 
temperatures, however, corrosive wear with the metals 
is experienced with CF2Br2. To obtain the proper halogen 
5 content, the two gases can be blended in optimum propor- 
tions and thus it is possible to obtain effective lubrication 
over a broad temperature range without corrosive wear. 
An object of this invention is to provide an extreme 
high temperature lubricant. 
An additional object of this invention is to provide a 
high temperature lubricant comprised of the mixture of 
halogen-containing gases. 
A further object of this invention is to provide a halo- 
gen-containing gas mixture €or high temperature lubrica- 
15 tion which minimizes corrosive wear. 
A still further object of this invention is to provide 
halogen-containing gas mixtures for high temperature 
lubrication of surfaces in solid contact. 
A still additional object of this invention is to provide 
20 halogen-containing gas mixtures that will form reaction 
films with various alloys wherein such films have desirable 
lubricating properties. 
0,her objects and many attendant advantages of the 
present invention will be apparent from the following 
25 detailed description of the invention. 
As a basis of this invention, it has been discovered 
that a gas blend of CFzBrz and CF& is found to be an 
effective lubricant to 1200" F. for various metal combina- 
tions. A 1 to 1 gas blend of the two compounds was 
30 found to provide a synergistic effect as will be seen from 
the following detailed results of experimentation. 
The apparatus used in determining the effect of the 
cornpounds as lubricants consists essentially of a rotating- 
disc specimen 2% inch diameter and a hemispherically- 
35 tipped rider specimen inch radius. The rider speci- 
men is stationary and in sliding contact with the rotating- 
disc specimen. The disc is rotated by means of an elec- 
tric motor through a variable-speed transmission. Loads 
are applied to the rider specimen by means of a dead 
40 weight system. The frictional force is measured directly 
by means of 4 strain gages mounted on a copper-beryllium 
dynamometer ring. The frictional force is continuously 
recorded on a strip-chart potentiometer. After the ex- 
periment the wear volume is calculated from the meas- 
45 ured diameter of the wear area on the rider specimen. 
The compositions of various alloys used in the particular 
tests are presented in the following table: 
10 
TABLE I 
Material IT Typical composition, percent by weight Average harclness, 1 Rockyell 
C I Si I Ni I Cr I Co I W I Mo I Other 
33 
29 
52-57 
52-55 
of metallic halide may form and thus result in oorrosion The gaseous lubricants are introduced into a tube 
of the surface. For example, a corrosion problem is 60 leader Inconel pot that encloses the disc and rider speoi- 
encountered in lubricating tool steel with a halogen-con- men. The Inconel pot is heated by means of strip heaters 
taining gas above 600" F. but the use of cobalt and nickel mounted on the outer walls in concentric ring heaters in 
base alloys eliminate the corrosion problem. the base of the pot. The strip and ring heaters are con- 
In gas lubrication where surface reactions are impor- trolled by individual Variac units. The temperature is 
tant, the gas must have the proper halogen content. It 65 measured by an Inconel-sheathed Chromel-Alumel ther- 
is necessary to have sufficient halogen present in the mocouple located along the side of the disc specimen. 
gaseous molecule to satisfy lubrication requirements and The temperatures which varied from 75" to 1200" F. 
yet not such an excess that would cause corrosion at high are read from an indicating potentiometer. The Inconel 
temperatures. The gas CF3Br has a single forming atom test chamber is purged for a 15-minute period prior to 
and provides effective lubrication at high temperatures. 70 actual starting of the run. The specimens are brought 
At room temperatures, however, insufficient bromine is to temperature in air before the period of purge is ini- 
present to provide adequate lubrication. The gas CF2Br2 tiated. The gas flow at a rate of 1 liter per minute and 
3,072,674 
4 
mixtures used in the purge were the same as those em- 
ployed in the run. At the completion of the purge the 
run-in procedure is initiated. Measurements show that 
less than 0.5% oxygen is present in the test chamber 
after purge. 5 1. A gaseous lubricant composition consisting essen- 
teachings. It is, therefore, 'to be understood that within 
the scope of the appended claims the invention may 
practiced other than as specifically described. 
What is claimed: 
TABLE I1 
Rider Wear (in.3/hr.~IO-5) 
Stellite 98M2 Rider Sliding on Hastelloy C 
Temperature,OF. 1 Air [ CFaBra 1 CF3Br 1:1 1 40% CFsBr, 
60% CFaBri 
40% CFzBri 
60% CF~B; 
The results of tests are shown in Table 11. In all fhe 
runs, the total amount of gas was one liter per minute. 
Thus, in the synergistic 1 : 1 mixture, there was 0.50 liter 
tially of from 40 to 60 percent CF2Brz and from 40 to 
60 percent CF,Br. j 
2. A gaseous lubricant composition consisting essen- 
per minute of each of the two gases. As can be seen, the 20 bially of 50 percent CF2Br2 and 50 percent CF3Br. 
1 : 1 mixture of CFaBr2 and CF3Br gave better wear results 3. A gaseous lubricant composition consisting essen- 
than either of the gases alone. The mixture of 40 per- tially of 60 percent CF2Br2 and 40. percent CF3Br. 
cent CF3Br and 60 percent CF2Br2 additionally gave 4. A gaseous lubricant composition consisting essm- 
better results than the use of either of the gases alone. tially of 60 percent CF3Br and 40 percent CF2Br2. 
The mixture 02 40 percent GF2Br2 and 60 percent CF3Br 25 5. A meth,od of lubricating metal surfaces comprising 
produced results slightly above the lowest values obtained the steps of enclosing said surfaces in a gastight chamber, 
when using the individual gases, but there still exists clear and circulating a gaseous lubricant composition c,-ns$t- 
evidence of a synergistic result, as it would be expected ing essentially of from 40 to 60 percentt CF2Bra and from 
that '. wear be above '.0205 40 to 60 percent of CF3Br through said chamber. in.s/hr.X 6. A method of lubricating metal surfaces comprising 
the steps of enclosing said surfaces in a gastight chamber, obtained using either of the gases alone. Essentially the 
land circulating a gaseous lubricant composition consist- same results are obtained when using a Rexdloy 33 rider sliding on Inconel X. 
ne of the of set forth in this in- ing essentially of 50 percent CF2Br2 and 50 percent of 
vention is not at all limited to the particular alloys set 35 CF3Br through -said chamber. 
j 
which is the mean between the values 30 
References Cited in the file of this patent forth in the testing of the lubricant. Obviously, many modifications and variations of the 
present invention are possible in the light of the above Lubricating Engineering, November 1958, p. 454. 


Gas lubricant compositions Patent

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