Surface modification of Al6061-SiC surface composite through impregnation of graphene, graphite & carbon nanotubes via FSP: A tribological study

Abstract

Fabricating high wear resistance Al matrix composite without sacrificing its ductility and thermal properties is a critical issue in the designing of Al-based composites. In present study, a detailed wear mechanism of Al-SiC surface composite modified by the impregnation of Graphene, Graphite & carbon nanotubes through friction stir processing (FSP) is documented. The results revealed that with SiC and graphene nanoplatelets (GNP) reinforcements the friction coefficient and specific wear rate decreased by ~34% and ~50% as compared to as-received Al6061 alloy respectively. On the other hand, combination of SiC and carbon nanotubes (CNT) reinforcements severely deteriorates the wear resistance of the composite. The layered structure, large specific surface area and the wrinkled morphology of the graphene flakes are the primary reasons for the increased wear resistance. The exfoliation of GNP to few layered graphene (FLG) under the effect of plastic flow stresses during FSP also contributes significantly to the improvement of surface properties. The abrasion is identified as the dominant wear mechanism in Al-SiC-Graphite & Al-SiC-GNP hybrid composite. Whereas, delamination due to adhesion with the counter surface is the leading mechanism in Al-SiC-CNT hybrid composite. Various characterization strategies such as microstructural characterization through SEM, interfacial study through TEM and phase analysis through XRD corroborate the results. Finally, GNP is identified as the best reinforcement among the carbon family for improvement in wear resistance of Al6061-SiC surface composite.