Contamination of vacuum environment due to gas emission stimulated by friction

Mechanical elements may produce significant contamination of ultrahigh vacuum due to emission of gases from materials under stress and rubbing. Composition of emitted gases and behavior of gas emission was studied for various materials and surface coatings of interest for vacuum engineering. It is suggested that gases dissolved and occluded in the material bulk (H2 and Ar) and tribochemical reactions (CxHy) are the main sources of gas emission. Frictional heating was discarded as the driving force for gas emission. Mathematical apparatus of specific parameters for characterization of gas emission is proposed.

► Gas composition and emission behavior are determined for materials and coatings.
► MSGE is caused by plastic deformation rather than by frictional heating.
► Mathematical apparatus of specific quantitative parameters for characterization of MSGE.