Evaluation of wear rate and mechanical properties of platinum-graphene nano-composite by molecular dynamics simulation

Abstract

As the energy industry develops and natural resources become more scarce, scientists are focusing their attention on finding new materials where comes the emergence of nanocom- posites and their applications in various sectors. Despite the increase in the discovery of novel nanocomposites, assessment of their mechanical and tribological characteristics is limited owing to the intricacy of their structures. In this study, one of the main goals is to evaluate the mechanical properties of platinum graphene nanocomposites (Pt-Gr NC) using molecular dynamics simulation. Pt-Gr NC was chosen for this study because of the extraordinary qualities of graphene as a fiber and platinum’s use in energy storage systems and other disciplines, such as biomedical and industrial ones. The study began with the material design and finding its proper interac- tion potentials. Then MD simulations of the system for both tensile and bending testing were done to find its mechanical properties, and the results showed that the mechanical properties of Pt were improved with the inclusion of graphene fiber. Almost a 35% of in- crement in Young’s modulus occurred with the inclusion of single layer of graphene with platinum. Validation of the results was also done with previously developed equation of mixture for bulk composites. After investigating the material’s mechanical characteristics and failure processes, it was found that Pt-Gr NC performed as predicted when subjected to tensile loads but badly when subjected to lateral loads. In addition, the effect of addi- tional graphene layers and temperature variation on the mechanical properties of the Pt-Gr NC were eventually investigated. MD simulation being a perfect method for studying the underlying complex behavior of friction and wear, a study of the tribological properties of this selected nanocomposite was also conducted. The change in coefficient of friction due to temperature variation showed a decreasing trend. The effect of variations in sliding velocity on friction and how a higher sliding velocity led towards material wear were also studied. The effect of wear rate due to different normal loads, as well as a comparison of wear rate with pristine platinum, were also investigated in this study. Results showed that, wear rate for Pt-Gr NC is higher than pristine Pt at different indentation depth. This study yields results applicable to the disciplines of nanocomposite and nanotechnol- ogy. Information on the mechanical properties and tribological characteristics of the Pt-Gr nanocomposite can help in the design and fabrication of supercapacitors, fuel cells, biosen- sors, etc., where this material is generally used. The research results could also help figure out what materials could be used instead to make structures stronger and more durable.