Fabrication and self-lubricating tribological characterisation of Cu–Ni/TiC/CaF2 composite for railway switch slide baseplate

Abstract

In this research study, composites based on Copper-nickel (Cu–Ni) alloys, reinforced with particles of titanium carbide (TiC) and calcium fluoride (CaF2), were fabricated by powder metallurgy at 900 °C. Experimental studies were conducted to evaluate the tribological behaviour of TiC/CaF2 reinforced Cu–Ni matrix composites against counterpart 90-UTS rail steel. The worn surfaces were characterized by an Optical microscope (OM), 3D profilometer, field emission scanning electron microscope (FESEM), energy dispersive spectroscopy (EDS) and Raman spectroscopy. The lowest coefficient of friction (0.30) and lowest wear rate (5.36 x 10−5 mm3/N.m) were observed in the case of Cu–Ni/5 wt% TiC + 4 wt% CaF2 among all the composites. Cu2O, NiO, TiO2, Fe2O3 and Fe3O4 were formed, as a result of the tribo-oxidation on the wear tracks, which significantly affected the wear behaviour and wear mechanism. The main wear mechanism of the Cu–Ni matrix-based composites was a combination of adhesive wear, tribo-oxidation wear, delamination and minor abrasive wear.