Dry sliding wear behavior of aluminum alloy 6082 - SiC composites through ex-situ casting process

Abstract

The applications of AA6082 alloys in the structural and transport are found to be more due its light weight. To improve strength to weight ratio and stress resistance, the carbides/oxides are added and this will leads to improvement in the mechanical properties and high stress sustainability. In this research work, AA6082 Metal Matrix Composite (MMC) is manufactured through the ex-situ casting process with the Silicon Carbide (SiC) reinforcements of 2.5 & 5 wt% and the microstructure evolution, hardness, dry sliding wear behavior and tensile properties of MMCs are investigated. As-cast AA6082 showed the dendritic microstructure with intermetallic eutectics. The presence of SiC particulates in AA6082 resulted in decreased grain size and equixed grains. The hardness of the tested as casted AA6082 samples was found to be 81 HV which has been increased to 93 HV and 107 HV and the tensile strength of AA6082 is increased by 16% and 41% by addition of 2.5 wt% SiC and 5 wt%SiC respectively due to the presence of the SiC particulates. At the same time coefficient of friction of AA6082 is found to be decreased by 11.8% and 20.5% for the testing load of 10N and the corresponding decrease in wear rates were found to be 50.8% and 70.3% respectively. The worn surface showed the continuous groove parallel to sliding direction with short cracks, bidirectional rough grooves with peeled-off SiC, unidirectional smooth scratches along the sliding surfaces for as-cast AA6082, AA6082-2.5 wt SiC and AA6082-5 wt SiC respectively that indicates the significant effects of SiC particulates on wear mechanism.