Tribological Performance Assessment of Porous Copper-Based Composite under Dry and Lubricated Conditions

The present investigation has been carried out with the aim of determining the frictional and wear behavior of porous copper-based composites. The porous copper-based composites have been prepared by using a novel approach for bearing applications, where the mixture of copper oxide and copper powder is blended with the hybrid 2D material, i.e., reduced graphene oxide-MoS₂ (rGO-MoS₂) by ball milling. The composites were sintered using microwave sintering technique having different compositions (0, 0.5, 1.0, 1.5 and 2.0 wt.% rGO-MoS₂), wherein rGO-MoS₂ served as the genesis of porosity. The density and hardness decreased with increase in rGO-MoS₂ content, and the relative density up to 62% is achieved. The tribological behavior was studied at the different loads of 4, 6, 8 and 10 N and constant sliding speed of 0.5 m s⁻¹ against EN31 ball counterface, while testing has been conducted under dry sliding and mixed lubricated conditions. Composites exhibit the low frictional characteristics as compared to the base material, and an increase in coefficient of friction and wear rate is observed with increase in load. The worn surface analyzed by the scanning electron microscopy and energy-dispersive x-ray spectroscopy revealed the oxide layer formation, abrasive wear and adhesion as major wear mechanisms in dry sliding conditions. Tribo-oxide layer formation and retention of lubricant in the pores account for the low friction and wear of the composites under single drop lubrication.