Influence of Graphene/h-BN and SiC/h-BN reinforcing particles on microstructural, mechanical and tribological characteristics of Al7075-based hybrid nanocomposites

Abstract

Aluminium (Al) based Metal Matrix Composites (MMCs) replaced conventional alloys in numerous sectors like the automotive to aerospace industries. In this investigation, Al7075/Silicon carbide (1 wt%)/Hexagonal-boron nitride (0.5 wt%) and Al7075/Graphene (1 wt%)/Hexagonal-boron nitride (0.5 wt%) hybrid metal matrix nanocomposites (HMMNCs) prepared using an ultrasonic-assisted melt-stirring squeeze casting process. To attain the homogenous mixing of hard ceramic/nanoparticles, reduce the aggregation effect and improve wettability of the reinforcing nanoparticles in the molten slurry. Reinforcement particles mixture (Silicon carbide (1 wt%)/Hexagonal-boron nitride (0.5 wt%) and Graphene (1 wt%)/Hexagonal-boron nitride (0.5 wt%)) have been ball-milled for the duration of 1 to 6 h (hrs). To analyze the morphology of the 1–6 h ball-milled hybrid reinforcing particles mixture was analyzed via scanning electron microscope (SEM). Moreover, microstructural investigation of the Al-based HMMNCs was performed using optical microscopy (OM), field-emission scanning electron microscopy (FE-SEM) and scanning electron microscope (SEM). Also, the dispersal of hybrid reinforcing particles mixture in Al7075-based HMMNCs was examined via SEM-equipped with x-ray mapping analysis. The fabricated Al7075-based HMMNCs are tested for their tensile strength, microhardness and tribological behavior by employing universal testing machines, Vickers microhardness tester and ball-on-disc instruments. Tribological characteristics of the Al7075-based HMMNCs were observed via ball-on-disc tribometer apparatus with load (10, 15 and 20 N), time (15 min) and speed (300, 600 and 900 rpm). While investigating, it is perceived that that the wear, tensile strength, hardness and microstructure characteristics of the Al7075/Silicon carbide/Hexagonal-boron nitride and Al7075/Graphene/Hexagonal-boron nitride HMMNCs were superior over the Al7075 alloy. It is found that Vickers and Rockwell hardness of the Al7075/SiC/h-BN HMMNCs were superior by 36.87% and 16.29%, respectively, over the Al7075 specimen. Whereas, UTS of the Al7075/Graphene/h-BN HMMNCs were superior by 38.19% over the Al7075 alloy.