Surface modification of Al6061 by graphene impregnation through a powder metallurgy assisted friction surfacing

Impregnation and homogeneous distribution of nanomaterials on metallic surfaces have always been a challenge for researchers in recent times. In the present work, authors demonstrate a surface modification of Aluminium by graphene impregnation through a novel powder metallurgy assisted friction surfacing (PMAFS) process. This modified friction surfacing technique involves two stages. In the first stage, an Aluminium-graphene composite tool is fabricated through a powder metallurgy route. In the second stage, this consumable tool is utilized for FS to obtain a composite coating layer on Aluminium surface. Experimental results show that the surface composite prepared by this modified friction surfacing technique does have impregnated graphene successfully in Al matrix. The obtained surface composites were characterized by using SEM, TEM, and XRD. Morphology and damage to graphene are studied by using Raman spectroscopy. Nanoindentation study was conducted for a various set of processing parameters with variation in graphene content. Further, the influence of graphene percentage and processing parameters on mechanical properties and microstructural changes were also studied. Composites prepared at relatively lower tool rotational speed with low content of graphene in the tool is found to have optimum mechanical properties with a homogeneous distribution of graphene in Al substrate. The nano-hardness of the surface composite is increased by 100% after impregnation of graphene nano platelets (GNP) with an optimum set of parameters.