Effect of Polarization Potential on the Tribocorrosion Behavior of 70/30 Cu-Ni Alloy

In this paper, the tribocorrosion behavior of 70/30 Cu-Ni alloy in 3.5 wt.% NaCl solution at different polarization potentials was investigated. The cathodic potentials (− 0.6, − 0.3 V_Ag/AgCl), OCP and anodic potentials (− 0.15, 0 V_Ag/AgCl) were selected for the tribocorrosion tests, and the wear marks were examined by optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), confocal laser scanning microscopy (CLSM) and x-ray photoelectron spectroscopy (XPS). The wear micro-morphology and chemical composition were characterized. The results showed that the tribocorrosion loss volume increased with the increase of polarization potential. At the cathodic potential (− 0.6 V_Ag/AgCl), flaking layer and furrow appeared on the surface of the wear scar, and the wear forms were delamination wear and abrasive wear. At OCP, the corrosion product layer produced by selective corrosion played a lubricating role, but the corrosion promoted the formation of subsurface cracks and holes, and the loss volume was about three times of that of the pure mechanical wear. Intergranular corrosion greatly accelerated material degradation when the polarization potential increased to 0 V_Ag/AgCl.