The influence of implanted transition metal ions on the adhesive wear of iron

Abstract

In a previous study, a model based on the ratio of adhesive to cohesive bonding energy was derived to predict relative wear rates of a variety of metal couples. Surface energy, or reactivity, is a function of the total atomic bonding energy of the atoms comprising the surface and may be varied independently through solid solution alloying. Therefore changes in surface composition should be reflected in the adhesive character and macroscopic wear behavior. Using a reciprocating Be-Cu right cylinder on high purity iron flat as a wear couple, the adhesive character was modified by ion implantation of cobalt, manganese, nickel, niobium, titanium, tungsten and yttrium into the iron flat at a dosage of 1 × 10 17 ions cm −2. The implantation energies were tailored so that the ion concentration vs. depth of penetration below the surface profiles were approximately equivalent. Implantation-induced residual stresses were determined prior to wear testing. The wear-induced surface and subsurface deformation was characterized with microindentation hardness measurements and scanning electron microscopy. A model is presented to explain the enhanced wear resistance of samples implanted with heavier, higher cohesive energy ions compared with those implanted with lighter, lower cohesive energy ions.