An investigation into the influence of frictionally generated surface temperatures on thermionic emission

Tribochemistry-including chemical reactions at sliding surfaces in contact-is an important factor in boundary lubrication and the formation of protective films. It is a complex subject quite different from conventional glassware studies and may involve effects of high temperatures produced by friction, the emission of charged particles and high pressure. In previous theoretical studies based on a general thermal model of sliding contact, results were presented for surface temperatures generated with pure metallic elements as well as ceramics. More recently, this model was extended to include thermionic emission of electrons. The current paper is motivated by the need to understand the connection between high surface temperatures and electron emission in sliding systems. The objectives are to examine theoretically the temperatures and resulting thermionic emission at the surface of selected sliding contact systems. Results are presented and discussed for 20 pure elements including 19 metals and 1 semi-conductor. The results of this investigation may be of value in examining and testing various film-forming hypotheses. For example, in the tribopolymerization concept of boundary lubrication, it is postulated that high surface temperatures are controlling for the surface polymerization of condensation-type monomers while the emission of low-energy electrons initiates polymerization of vinyl-type addition monomers. (C) 2003 Elsevier B.V. All rights reserved.