Tribological performance of aluminium hybrid self-lubricating composites reinforced with green synthesized graphene

In this contemporary research work, graphene nanosheets were synthesized by the green method using agricultural waste and characterized by FESEM, XRD and Raman spectroscopy. Vortex liquid metallurgy technique is used to fabricate AA7075 hybrid composites reinforced with graphene and hard ceramic. The samples were evaluated for tensile strength, hardness and tribological behaviour. The influencing wear parameters percentage of graphene reinforcement, load, sliding speed and sliding distance were varied three levels each. An empirical relationship was formulated using face-centred central composite design considering wear weight loss and coefficient of friction as output responses. The influencing parameters on the output responses were determined by employing analysis of variance and the objective is to find the optimal process parameters. Graphene enriched the mechanical and wear behaviour. The composite having a 0.5 reinforcement percentage of graphene exhibited higher hardness and higher tensile strength. The optimal combination of tribological parameters for minimum wear loss and friction coefficient was found for 0.5% of graphene reinforcement, 30 N load, 2.5 m s(-1) sliding speed, 1000 m sliding distance. The worn surface was also analyzed using FESEM and inverted microscope images.