Reactive wetting of metallic/ceramic (Al/α-Al₂ O₃ ) systems: a parallel molecular dynamics simulation study

Authors: GÜRCAN ARAL

Abstract: The reactive wetting process of a flat solid alumina (α-Al₂ O₃) ceramic surface by metallic aluminum (Al) nanodroplets with different shapes (spherical, cylindrical, and layer) is studied using parallel molecular dynamics (MD) simulations based on a variable charge MD method, with focuses on heat transfer, mass transfer, and the structure of the reactive region at the Al/α-Al₂ O₃ interface. We find that the diffusion of oxygen (O) atoms from the substrate into the droplet leads to the formation of a continuous layer of reaction product at the interface. The diffusion length of oxygen atoms into the spherical Al droplet is found to be ~7.3 Å, and the number density of O atoms at the ~5 top layers of the substrate decreases substantially. As a result, the structural correlations near the reactive region differ considerably from those in the solid substrate. Heat generated by the exothermic reactions in the reactive region is transferred to both the substrate and the droplet. The heat transfer is found to be sensitive to droplet shape.

Keywords: Variable charge method, molecular dynamics simulations, wetting, alumina, aluminum

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