Shock Compaction of Graphene Doped Yttria Stabilized Zirconia: An Experimental and Computational Study

Yttria stabilized zirconia (YSZ) is a broadly used ceramic due to its impeccable hardness and thermal stability. Limitations of the material, however, subsist within its fracture toughness. Literature indicates that shock consolidation may enable production of composite YSZ and graphene mixtures with improved fracture toughness and other material properties while maintaining the material’s nanostructure dimensionality. Therefore, investigation of the compaction phenomena at non-equilibrium states will provide informative results to be used in the fabrication of bulk graphene-YSZ composites. Computational molecular dynamics (MD) simulations and impact experiments are conducted to explore and characterize the dynamic response of the YSZ variants. Molecular dynamics simulations studied the non-porous dynamic behavior observed for various graphene and YSZ mixtures. Impact experiments compacted YSZ and graphene/YSZ variants at velocities spanning 315-586 m/s. Two distinct particle sizes of YSZ were investigated (micrometer and nanometer), as well as weight percentage of graphene added to the powdered YSZ (0%, 1%, 3%, 5%). Experimental results portray many physical mechanisms exhibited during the compaction/consolidation process, such as heterogeneity and porosity. Comparison of the MD and experimental results map the thermodynamic state of the materials, defining the non-equilibrium states exhibited by the specimens

Modeling and simulation in tribology across scales: An overview

This review summarizes recent advances in the area of tribology based on the outcome of a Lorentz Center workshop surveying various physical, chemical and mechanical phenomena across scales. Among the main themes discussed were those of rough surface representations, the breakdown of continuum theories at the nano- and micro-scales, as well as multiscale and multiphysics aspects for analytical and computational models relevant to applications spanning a variety of sectors, from automotive to biotribology and nanotechnology. Significant effort is still required to account for complementary nonlinear effects of plasticity, adhesion, friction, wear, lubrication and surface chemistry in tribological models. For each topic, we propose some research directions