Friction and Shear Sensitivity

Because of the low friction coefficient of PTFE/PTFE ( X = 0.04), PTFE-based materials usually are not very prone to ignition by friction. Thus, there is no 

A number of commercial polychlorotrifluoroethylene products such as Fluorolube and Kel-F (oils, grease and powders) when used for machining aluminium yield explosive reactions under high shear loads. This kind of reactivity is rarely observed with pure fluorocarbons. Thus, it is assumed that the high reactivity stems from the chlorine connected to the polymer that is more easily abstracted than fluorine. In addition, thermal reaction between A1 and Kel-F oil has been observed at temperatures as low as 218 °C, whereas a fully fluorinated grease does not react until about 648°C [13]. Tribochemical-induced reaction between fluorocarbons and certain metals has been confirmed by Electron Spectroscopy for Chemical Analysis (ESCA) investigations on PTFE samples filled with both aluminium and zinc [14, 15]. 

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Friction and Shear Sensitivity 301 Table 19.1 BoE impact energy of various metal/PTFE compositions [7, 8]. 

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