SEDL / STP / STP1105-EB / STP17658S

Wear by Chemical Reactions in Friction Contacts

Lauer, JL
Professor of Mechanical Engineering and Director, Institute for Wear Control and Tribology at Rensselaer Polytechnic Institute, Troy,

Pages: 14    Published: Jan 1991

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Abstract

In friction contacts chemical reactions can occur between the surrounding fluid and the solid surfaces in unusual ways. Overcoats are formed on and partly or wholly removed from the surfaces by wear. Reactions between the substrate and/or the overcoat and the environment become diffusion-controlled and can even become oscillatory. Analysis of diffusion-controlled reactions shows that faster-than-expected reaction rates can result from tribologically thinned overcoats. Further reactions of the overcoats and their mechanical removal can be modeled in ways used in biology to depict population changes as growth rates of predators and prey. Examples are simultaneous sulfiding and oxidizing of steels at low temperatures (< 100°C) and the formation of carbonaceous layers on both metals and ceramics by carbon-containing gases in various temperature ranges between ambient and 700°C.