New lubricants

The ensuing chemicophysical reactions have the potential to change the nature of both mechanical components and lubricants. Pressures may reach extremely high levels, possibly several GPa. The effect of such pressures on insulating materials may be to produce very intense electric fields capable of locally generating a plasma. By enabling accurate analysis at the microscopic level, photoemission spectro-microscopy is one of the chemical characterisation techniques that can best aid the understanding of phenomena of this nature.

Elettra's contributionIn work performed at Elettra, a variety of steel specimens has been studied while subjected to mechanical forces in the presence of lubricants of various formulations. The use of a photoemission microscope allowed areas of specimens exposed to friction to be characterised both morphologically and chemically. In the particular case of lubricants containing sulphur, it was possible to confirm lubricant decomposition, and the existence of residues, at precise specimen locations. Chemical changes within the steel, and spatial reorganisation of the alloy elements and crystallographic phases, were also revealed.
The development of investigation techniques involving nanomaterials and their characterisation makes possible a new approach to the problem of friction which may help to explain the basic processes involved, and thus allow the behaviour of mechanical systems to be predicted at the macroscopic level.

Facility: Beamline ESCA Microscopy.