Synergetic influence of TiC np and graphite particles on tribological performance of Cu based composites prepared by flake powder metallurgy

Abstract

The Cu base composites play a key role in multiple industrial applications such as bearing materials and carbon brushes owing to their superior thermal, mechanical and tribological features. Therefore, in the present investigation, synergetic influence of nano titanium carbide (TiC_np) and graphite particles (Gr_p) on tribological behaviour of Cu base self-lubricating composites have been studied. The composites with fixed 5wt% of Gr_p and varying amounts (1.5wt% to 4.5wt%) of TiC_np were prepared via flake powder metallurgy (flake PM) technique. The sintered samples were characterized by different techniques for phases, physical, morphological and mechanical properties. Pin-on-disc (POD) tribotester has been used to analyse the tribological behaviour of composites in dry sliding condition by varying loads (10 N to 30 N) and sliding velocities (0.75 m/s and 1.5 m/s) for a fixed sliding distance of 2000 m. The results indicate the successful formation of Cu-Gr_p and TiC_np-reinforced Cu-Gr_p composites. With addition of Gr_p, the wear rate and coefficient of friction (COF) of Cu matrix is reduced. The wear rate is further reduced with the incorporation of TiC_np particles. But, the COF shows the enhancement. The composite having 5wt% Gr_p–4.5wt% TiC_np shows the minimum wear and maximum hardness. The energy-dispersive spectroscopy (EDS) elemental mapping of worn surfaces indicates that TiC_np mechanically interlocks the graphite at the interface and prevent its removal and reduces the wear rate. The worn surface investigation also shows that the dominant mechanism of wear for pure Cu sample is delamination in nature. However, the mechanism of wear for TiC_np-reinforced composites is a combination of abrasive and delamination wear.