Geometrical aspects of nanofillers influence the tribological performance of Al-based nanocomposites

S Mohammadi and A Montazeri and HM Urbassek, WEAR, 444, 203117 (2020).

DOI: 10.1016/j.wear.2019.203117

With respect to the inherent poor tribological behavior of aluminum (Al), reinforcement of this metal with nanoscale fillers is a promising research area with significant industrial impact. Accordingly, in the current research, we have probed the tribological characteristics of Al- based nanocomposites embedded with nanofillers of different geometries. Targeting this purpose, a series of nanoscratching tests based on molecular-dynamics simulations is carried out to explore the effect of spherical silicon carbide nanoparticles and graphene monolayers on the coefficient of friction (COF) of the baseline Al matrix. The results reveal that while the former inclusion reduces this parameter, COF is enhanced in the presence of platelet graphene sheets. To find out the underlying mechanism, the microstructural evolutions are thoroughly examined in the interfacial area by means of the dislocation extraction analysis. Our findings are supported by an in-depth study on the pile-up features and more pronounced plastic deformation zones in the samples. Furthermore, to overcome the deteriorating influence of graphene on the COF of the Al matrix, various composite systems are designed which differ in the depth where the nanofiller was positioned. Finally, a solution is presented to increase the mechanical performance of the Al- based nanocomposites in the presence of graphene sheets without sacrificing their tribological behavior.

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