Electron Transfer through a Natural Oxide Layer on Real Metal Surfaces Occurring during Sliding with Polytetrafluoroethylene: Dependence on Heat of Formation of Metal Oxides

摘要: Electron emission (EE) from real metal surfaces occurring during sliding contact with a polytetrafluoroethylene (PTFE) rider has been investigated using the thermodynamic data of oxides and X-ray photoelectron spectroscopy (XPS) intensity ratio oxygen/metal on surfaces. EE was termed triboelectron (TriboEE). Rolled sheets 18 types were used. The metal‒oxygen bond energy calculated heat formation oxide, (D(M–O)), shown to be key factor in dividing into two routes, so-called Schottky effect tunnel effect, due surface oxide layer. metals periodic groups 4 (Ti Zr), 5 (V, Nb, Ta), 6 (Mo W) maintained higher values D(M–O), while, moving down groups, TriboEE increased, being ascribed former route. In 10 (Ni, Pd, Pt) 11 (Cu, Ag, Au), D(M–O) decreased but increased significantly, which can attributed latter Furthermore, increase electrical conductivity metals, became remarkably high, while value fell rapidly almost constant. XPS results showed that dependence core O1s O1s/metal different between 4, 5, 6. It concluded that, under electric field caused by friction PTFE, electron small predominantly tunnels layer as barrier, large values, passes over top barrier.