Tribological performance of Cu-silica sand hybrid composite reinforced with graphene nanoparticles by electric resistance sintering: Experimental studies and modeling

In the present work, copper metal matrix composites (CuMMCs) were developed using the electric resistance sintering (ERS) technique. Micro-particles of silica sand (5 wt%) and graphene nanopowder (0.1, 0.2, & 0.3 wt%) were added as reinforcement in the copper (Cu) matrix. Green compacts were pre-sintered at 600 °C in a tubular furnace containing N2 gas, then finally sintered through resistance heating and conduction heating simultaneously in high-density graphite die by applying a plain direct current (200–400 A) of low voltage (3–5 V). Characterizing the hybrid composites by X-ray diffraction, energy dispersion spectroscopy, scanning electron microscopy (SEM), and Raman spectroscopy showed the presence of Cu, sand, and graphene nanopowder. A uniform dispersion of the reinforcement particles was found in the prepared composites. Further, the incorporation of 0.2 wt% graphene with a sintering temperature of 900 °C resulted in the maximum relative sintered density (RD) and hardness (RH) of 6.98 g/cm3 and 73 HRB with a minimum wear rate (WR) of 0.00550 mg/s, respectively. In addition, the average coefficient of friction (COF) was found to be 0.44 for the composite having 0.3 wt% graphene. The RSM predicted optimum values of 7.216 g/cm3, 68.989 HRB, and 0.006 mg/s for RD, RH, and WR, corresponding to the 0.144 wt% graphene and 900 °C sintering temperature. The % error between the experimental and predicted RD, RH, and WR values was found to be 1.409 %, 1.950 %, and 3.01 %, respectively. Moreover, the SD values for the three output values were 0.270, 0.475, and 1.514, respectively.