Modeling nanoparticle agglomeration in the centrifugal method to evaluate heat-resistant functionally graded materials

Functionally graded materials (FGMs) can be fabricated using the centrifugal method, and the nanoparticle distribution in the matrix affects the FGM properties such as heat resistance. In this study, we developed a multiphysics simulation using the kinetic Monte Carlo (KMC) simulation and finite element method (FEM) to investigate the fabrication process of FGM and the resulting material properties, respectively. In the KMC simulation, we modeled the agglomeration and gravitational sedimentation of nanoparticles during the centrifugal fabrication process; thus, we determined the nanoparticle distribution in the FGM. The fabricated FGM nanostructure depended on the Peclet number, which was defined based on the rate ratio of solvent evaporation and nanoparticle diffusion. Thereafter, we performed FEM analysis to examine the heat resistance property of FGM, in which 2D quad mesh was adapted to express fine nanoparticles. We determined the thermal conductivity of FGM by assuming copper nanoparticles and epoxy resin as constituents. The thermal conductivity of FGM depended mainly on the Peclet number; the gravity had little influence. In addition, we found that the FGMs consisting of elliptical nanoparticles exhibited higher thermal conductivities than those consisting of circular nanoparticles. The presented simulation could be useful in examining fabrication conditions to achieve the improvement of heat-resistant FGMs using nanoparticles. Graphical Abstract