Molecular dynamics simulation and test characterization of metal migration behavior in antimony-impregnated graphite

The research commenced with the synthesis of antimony-impregnated graphite composites, designated as C/Sb20 %, incorporating 20 % by weight of antimony. These specimens were subjected to a battery of tests employing the high temperature and high speed friction test bench and EDS, TEM, and XRD. Furthermore, through the deployment of molecular dynamics simulations, this paper elaborates on the construction of both planar and spherical models of the tungsten carbide (WC) structure alongside a comprehensive structural model of C/Sb20 %. Leveraging the canonical ensemble (NVT) and a diverse array of potential functions, including Morse and embedded atom model (EAM)/alloy potentials, the study delves into the wear dynamics and sliding friction phenomena at the interface of the C/Sb20 % friction pairs. Notably, findings from the simulations reveal a dramatic decline in antimony concentration within the C/Sb20 % samples, plummeting from an initial 19.6 % to 6.89 % over an experimental period of 4000 s, signaling a substantial depletion of antimony. Concurrently, the emergence of Sb2O3 and Sb2O5 oxides was observed, indicating oxidative phenomena. Further elucidation from FIB-TEM analysis confirmed that the antimony lattice within the C/Sb20 % consistently exhibited a face-centered cubic (FCC) configuration. Integrating insights from molecular dynamics simulations with SEM analyses conducted before and after experimentation, this study unveils the extraordinary activity and "softening" of antimony flake structures under extreme conditions. This transformation, from flake to agglomerated forms, coupled with sliding friction, leads to the disruption of the graphite's internal structure, facilitating the continuous efflux of antimony and, consequently, diminishing the structural integrity of the graphite. This degradation not only compromises the graphite's mechanical properties but also escalates the risk of secondary wear through the formation of metallic oxides.