Formation of self-organized patterns on aluminum substrates by atmospheric pressure plasma jet for surface engineering applications

Abstract

Aluminum (Al-2024) substrates were exposed to an atmospheric pressure plasma jet (APPJ) produced by a rotating arc device in air. For short nozzle-to-substrate distances, transient streamers were transferred to alter large-scale metallic surfaces. Through judicious control of the operating conditions, in particular the plasma absorbed power, air flux, distance from the jet head, scanning speed, and number of passes, self-organized patterns appeared on the aluminum substrates. Confocal surface topography, scanning electron microscopy, x-ray diffraction, and energy-dispersive x-ray spectroscopy revealed bump-like, heavily-oxidized aluminum microstructures grown on top of a layered metallic surface. Depending on the operating conditions, the bumps are either isolated or linked as serpentines. The plasma-treated surfaces with self-organized, multilayered and multiscale features identified in this work highlights a promising structure for many surface engineering applications.