Effect of nanometer thin metal film on triboemission of negatively charged particles from dielectric solids

Recent extensive studies of triboemission of electrons revealed a key role of insulating capabilities of solids forming sliding contact on the intensity and behavior of emission processes. Also, it was found that the dominating emission mechanisms differ for insulators and conductors. In consideration of these substantially different natures of electron triboemission from solids of different insulating capacities, a study of heterogeneous conductor-insulator systems is of strong interest. Triboemission of negatively charged particles has been studied for soda time glass substrates both bare and covered with magnetron-sputtered At films with thickness in the range from 5 to 30 nm. Results showed that continuous 5 nm thick At film separating the substrate and the pin slider completely inhibits triboemission in inert atmosphere. As the wear of the film proceeds and the slider comes into direct contact with substrates, the emission intensity starts to rise. The intensity of the emission depends on the degree of wear of the metal film and is proportional to the applied normal load. Microscopic analysis of wear tracks showed that the presence of even separated islands of metal film is responsible for 2 to 3 times decreasing of emission intensity. (C) 2002 Elsevier Science Ltd. All rights reserved.