Evaporation of a sessile droplet resting on a thin vanadium dioxide film

Mariia Aleksandrovych, Guillaume Castanet, Ali Belarouci, Ophélie Caballina, Sergii Burian, Leonid Bulavin, Fabrice Lemoine, David Lacroix, Mykola Isaiev. Evaporation of a sessile droplet resting on a thin vanadium dioxide film. AIP Conf. Proc. 5 November 2019; 2170 (1): 020001. https://doi.org/10.1063/1.5132720

The paper is devoted to the study of the evaporation of water sessile drops resting on a smooth surface consisting of a vanadium dioxide thin film (∼150 nm) covering a sapphire substrate. Vanadium dioxide is considered because of the promising applications it is expected to have in new technologies for heat waste recuperation. Water drops are deposited on the substrate heated at different temperatures from 20 to 80°C, and the time dependence of the droplet shape is registered with the use of shadow imaging. This reveals that the three-phase contact line remains pinned during most of the drop lifetime, while the wetting contact angle as well as the drop volume are continuously changing. With the help of image processing, the vaporization rate of the drop is calculated. It is found that it is almost constant with time, and increases exponentially with the temperature of the substrate, well in agreement with theoretical models developed to describe the evaporation of drops with a pinned contact line.