Mechanisms of wear of metal by nitrile rubber under boundary lubrication conditions

Abstract

AbstractThe wear mechanisms for metal being worn by nitrile rubber under boundary lubrication conditions were investigated. We examined the surface profiles of both metal and rubber with SEM, and studied the chemical states of the elements in both surfaces with XPS. The functional groups in the rubber were analysed with FT‐IR. Under the action of shear forces, the metal lattice was disordered and new dislocations were formed; as a result, the chemical activity of the metal was increased. The macromolecular chains of the nitrile rubber and the alkane chains of the mineral oil were broken at stress concentration sites. These broken macromolecular chains produced active macromolecular free radicals, which reacted with the activated iron atoms and iron oxides, and generated a metal‐polymer film on the metal surface. This metal‐polymer film was destroyed and removed by the action of the debris on the sliding surface. Thus the rubber wore away the metal. Under boundary lubrication conditions with mineral oil, the physical processes of wear of T10 steel by nitrile rubber are microcutting and surface peeling.