Investigation of microstructural, mechanical and corrosion properties of graphene nanoplatelets reinforced Al matrix composites

Abstract

Graphene nanoplatelets (GNP) were utilized as reinforcement for Al matrix with the aim of exploiting its extremely high mechanical properties. GNP reinforced composites were prepared via powder metallurgical processing route based on mechanical alloying, cold pressing and pressureless sintering. 0.5 to 2 wt% of GNP were incorporated into the aluminum via mechanical alloying up to 8 h in a high-energy ball mill. The mechanically milled powders were compacted by two different methods as uniaxial cold pressing and cold isostatic pressing. The prepared powders and bulk samples were characterized by differential thermal calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometry (EDX), optical microscopy (OM), and Archimedes density, microhardness and dry sliding wear tests. Additionally, corrosion properties of the Al-GNP composites were determined by the Tafel exploration method. The results showed that the optimum GNP amount could be expected as 0.5 wt%, which enhanced the microhardness and wear resistance values of the Al from 84.5 ± 1.98 HV and 0.7384 mm3 to 199.4 ± 1.88 HV and 0.4476 mm3, respectively. However, this amount of graphene addition tended to slightly deteriorate the corrosion resistance of Al.