Intercalation Compounds: A New Class of Materials as Advanced Solid Lubricants (Wear Life Studies and Differential Thermal Analysis).
NAVAL AIR DEVELOPMENT CENTER WARMINSTER PA AIRCRAFT AND CREW SYSTEMS TECHNOLOGY DIRECTORATE
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Using graphite as a model host compound the process of intercalation, i.e., the insertion of foreign atoms or molecules between molecular planes of layer-structured solids has been shown to provide new material-with intrinsic lubricating properties substantially more beneficial than those currently available. A synergistic lubricating effect has been uncovered between intercalated metal chloridegraphite species and the non-intercalated metal chloride. A greater than seven-fold increase in endurance life compared to ordinary graphite has been demonstrated for CoCl2 intercalation compounds using the Falex lubricant tester. Pure intercalation compounds of CoCl2 and FeCl3, i.e., free of nonintercalated metal chloride exhibited a 2.5 fold increase in endurance life. Thermal analyses have shown that these compounds are stable to 325 deg C in an inert atmosphere. A mechanism has been proposed to explain the lubricating action based on a gradual decomposition of intercalation compounds at metal-to-metal contact junctions where hot spots can reach temperatures as high as deg 1000 C. The intercalated species which comes out of the graphite crystal then reacts with the metal to form a low shear strength solid which prevents further metal-to-metal contact and thus minimizes wear. Author
- Lubricants and Hydraulic Fluids