Interface analysis for diamond-like carbon film sliding against 9Cr18 steel under current-carrying conditions

Abstract

In this work, the tribological behavior and interface material evolution of H-free DLC film were investigated under current-carrying conditions in dry contact, using 9Cr18 steel balls as counterparts. Friction surfaces were examined using scanning electric microscopy, energy dispersive spectroscopy, and Raman spectra. Results showed that high current leads to obvious friction instability. The current direction significantly affects the friction behavior of the DLC film/9Cr18 steel contact. When the forward current increased to 1.0 A, DLC film severely wore, and local DLC film detachment occurred within sliding tracks. Graphite-like carbon was transferred to 9Cr18 steel ball surfaces in some cases but it did not show a good correlation with the friction behavior changes of DLC film. Based on elemental analysis, the formation of metal oxides on steel surface may influence the friction and wear behavior of DLC/9Cr18 steel contact under current-carry conditions. Additionally, the current clearly induces the graphitization transformation of DLC carbon matrix depending on the specific current conditions, which accelerates the wear of DLC film.