This lubricant contains MoS2, and other lubricating pigments in apolymide high temperature resin and was developed by MidwestResearch Institute, Kansas City, Missouri in connection with acontract with the NASA Marshall Space Flight Center, Huntsville,Alabama. NPI has been licensed by MRI to formulate, apply andmarket this lubricant since 1968. This lubricant was developed foruse at temperatures up to +500°F and in hard vacuum environments.NPI-425 has excellent wear life, having 3 to 5 times longer wearlife than MIL-L-8937 lubricants at room temperature and 5 to 10times longer at 450 F. It passes ASTM E595 outgassing requirementsand is radiation resistant. The nominal thickness of this lubricantis 0.0002 to 0.0004 inches and is cured for 1 hour at +300°Ffollowed by 1 hour at +575°F and, therefore, would not beconsidered suitable for use on some metallic substrates such asaluminum. Tests have shown, however, that acceptable performancecan be obtained by increasing the +300°F cure time to 5 hours andeliminating the +575°F cure procedure. Tests also show that thislubricant has a very constant and low coefficient of frictioncompared to other lubricants.
Wear life testing is routinely conducted using the Falex Pin andV-Block tester, per ASTM D2625-69 Procedure A. base material:V-Blocks AISIC 1137 Steel, Pins SAE 3135 Steel; average wear lifeis 7.65 hours. Load Carrying Capacity tests have also been run perASTM D2625-69 Procedure B with test pieces reaching the 4500 lbload, and continuing to run for approximately twenty five minutesbefore failure. More information about the Falex Pin and V-Blocktester can be found in the Wear Life Testing information area underNPI-1220.
