FED-STD-791D
8.4 Petroleum ether (O-E-751) [1,4,0].
9. PROCEDURE
9.1 Perform the test as follows:
a. Weigh 3 to 5 g of the grease to be tested to the nearest mg and distribute
as a thin layer in a 125 mL Erlenmeyer flask prior to adding 90 mL of a
50-50 mixture by volume of n-hexane and oleic acid. (See Note 1).
b. Warm the flask for approximately 1/2 h on a steam bath with occasional
agitation until all lumps have disappeared and the molybdenum disulfide
is dispersed.
c. Filter the contents of the flask through a previously prepared and weighed
(to the nearest mg) Gooch crucible. Wash the flask and crucible with
approximately 10 mL of a 50-50 mixture by volume of oleic acid and
n-hexane, followed by three washings with petroleum ether. (See Note 1.)
NOTE 1:
Caution. n-Hexane and petroleum ether are both toxic and flammable. Do
not breath their fumes nor allow them to come in contact with the skin.
Keep flames away from the n-hexane and petroleum ether.
d. Dry the crucible and contents at 100C for 1/2 h, cool in a desiccator to
room temperature and weigh. (See Note 2).
NOTE 2:
The purity of MoS2 powder may be determined in accordance with test
method No. 3710 or by means of spectrochemical analysis.
10. CALCULATIONS
10.1 Calculate the percentage of molybdenum disulfide as follows:
Increase in weight of crucible
Percent molybdenum disulfide (as insoluble matter) =
* 100
weight of sample
11. REPORTING
11.1 Report the percent molybdenum disulfide as insoluble matter.
12. PRECISION
12.1 Precision data have not been developed for this method.
Method Prepared by:
Navy - NADC - 1986
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