Thermal hysteresis in wettability and the Leidenfrost phenomenon

Abstract

The Leidenfrost temperature (TL), at which the liquid drop lifetime peaks on a superheated surface, is believed to be wettability dependent. Here, we show that the wettability effect on TL is subject to the history of the surface temperature. Observing a water drop evaporating on a polished stainless-steel surface heated from 100 to 400∘C in argon gas, we find TL≈265∘C. We then repeat the experiment along decreasing temperature and find a TL increase by 10 K, i.e., TL≈275∘C. This thermal hysteresis is due to a reduced contact angle during heating. Once hydrophilized, the hysteresis disappears until the contact angle recovers. Similar observations are made in the air where oxidation is possible. Published by the American Physical Society 2024