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THE SLIDING OF PTFE ON PTFE.
DU PONT DE NEMOURS (E I) AND CO WILMINGTON DEL ENGINEERING MATERIALS LAB
In sliding tests, a weighted sled with PTFE runners was pulled over a PTFE track. The sliding velocity was measured as a function of tangential load and ambient temperature for two normal loads. The results have led to treating the sliding phenomenon as an activated viscous flow process relating sliding speed to force of friction and absolute temperature. An activation energy of about 7 kcalmole was found. The size of the kinetic unit was estimated. Electron microscopy was used to examine the sliding surfaces very thin films of PTFE were extracted during replication. Shear in these films and their deformation is held responsible for the viscous sliding behavior. The effect of the crystalline transitions at 19 and 30C was investigated. Time effects were noted throughout the entire test program and documented. Author
Rept. for 15 Feb-15 Aug 64,
AF33 615 1201