| 1. |
- Wåhlin, Anders, et al.
(author)
-
Sliding electrification of Teflon by metals
- 1974
-
In: Journal of Applied Physics. - : American Institute of Physics (AIP). - 0021-8979 .- 1089-7550. ; 45:5, s. 2058-2064
-
Journal article (peer-reviewed)abstract
- The electrification of a system consisting of a metal and Teflon (polytetrafluoroethylene) has been investigated in vacuum under relative motion. A plane strip of Teflon was moved in relation to a metal electrode connected to an electrometer, which permitted the electrification charge to be continuously recorded. The electrification current was found to be closely proportional to the velocity, and it was practically independent of the radius of curvature of the tip of the electrode. The normal force was also varied, and the linear charge was found to be proportional to the square root of this force. Electrodes of Al, Au, Cu, Dural, Mg, Ni, and Pt were used, and the charge deposited was found to be linearly dependent on the metal work function, except for a large anomalyin the case of Cu. For a given metal the charge was shown to be closely proportional to the area swept out by the electrode on the insulator surface. The linear dependence of charge on metal work function and the short charging time (0.06 s) observed indicate that electrons from the metal fill empty surface states in the insulator up to a level corresponding to the Fermi level of the metal. The surface-state density of Teflon was found to be 7x 1010 eV-l cm-2.
|
|
| 2. |
- Wåhlin, Anders, 1942-
(author)
-
Static electrification of teflon by metals
- 1973
-
Doctoral thesis (other academic/artistic)abstract
- The electrification of a system consisting of a metal and polytetrafluoro-ethylene (Teflon) has been investigated under relative motion. First, the electrification charge received by the insulator was measured when velocity, radius of curvature of the metal electrode and normal force were varied. The measurements were performed both in atmospheric pressure and later under vacuum, since electrical breakdown sometimes limited the charge of the insulator.The results of these investigations indicated that the electrification charge received by the insulator is proportional to the real area of contact. Electrification in the sliding mode might therefore be analysed and interpreted as simply as in lifting experiments.Electrification experiments were then carried out using several metals,and a linear relation was found between the insulator charge density and the metal work function. This result together with the short charging time observed suggest a charging mechanism, in which electrons from the metal fill empty surface states in the insulator up to a level corresponding to the Fermi level of the metal.
|
|
| 3. |
|
|
