Application of alumina/graphene nanocomposite to enhance the surface quality of Al7175-T74 specimens

The burnishing process is one of the non-removal finishing processes, which is employed to enhance surface quality, corrosion property, and surface microhardness. In this study, the dry burnishing process was performed on the surface of Al7175-T74 specimens. Furthermore, nanofluid containing alumina/graphene nanocomposite was employed to perform the Nano burnishing process on the same specimens. The results show that the arithmetic surface roughness parameter in nanofluid burnished samples is decreased by approximately 0.277 , 0.233  and 0.345  for the penetration depths of 0.2, 0.3, and 0.4mm compared to those of dry burnishing process. Moreover, microhardness values in Nano and dry burnishing processes are directly related to the penetration depth parameter. The results reveal that the values of microhardness for the nanofluid burnished samples with four penetration depths of 0.2, 0.3, 0.4, and 0.5 mm are increased about 3, 28, 42, and 39 Vickers comparing to those values of the dry burnishing process. The results prove that the minimum surface roughness and maximum microhardness values can be reached in Nano and dry roller burnishing processes at the penetration depth of 0.4 mm.  Eventually, analyzing elements distribution on the surface of burnished aluminum alloy specimens confirm that the alumina/graphene nanocomposite is embedded in the burnished surfaces during Nano burnishing process.