Modulating\nWetting States of Molten Aluminum Droplets\non SiO<sub>2</sub> Surfaces via Vertical Sinusoidal Vibrations

Vibration affects the wetting behavior of droplets, and\nit is feasible\nto use vibration to modulate the adhesion characteristics of droplets.\nIn this paper, the effect of vertical sinusoidal vibrations on the\nwettability of molten aluminum droplets on the substrate surfaces\nof smooth and with nanopillars is investigated. The increase in the\nfrequency or amplitude of the vibration leads to a rise in the interfacial\npotential energy between the molten droplets and the substrate, which\nin turn leads to the occurrence of the Wenzel–Cassie transition.\nOnce the vibration frequency reaches the threshold values, the molten\ndroplets leave from the substrate, that is, dewetting occurs. The\nmolten droplets in the Wenzel state undergo a Wenzel–Cassie\ntransition before dewetting occurs. A phase diagram describing the\nfrequency thresholds at which the molten aluminum droplets undergo\ndewetting and the Wenzel–Cassie transition at different amplitudes\nis plotted. For a specific amplitude, the frequency of vibration required\nfor dewetting to occur in molten aluminum droplets in the Young state\nis lower than that in the Wenzel state. The needed vibrational frequency\nfor dewetting or the Wenzel–Cassie transition decreases with\nincreasing amplitude.