Sessile droplet evaporation on the surface of a liquid metal

Abstract

Sessile droplet evaporation on a liquid gallium surface is reported. Liquid gallium has a super smooth flexible surface, but an oxide film is easily formed in ambient air. Two methods were used to reduce the influence of the oxide film: using HCl vapor treatment and putting the liquid metal in a glove box with an oxygen concentration of less than 1 ppm. The experimental results show that the existence of an oxide film will affect the wettability of the liquid gallium surface, and then affect sessile droplet evaporation. In the low oxygen environment, the evaporation of hexane droplets and water droplets on the surface of the liquid gallium has the largest spreading diameter and the shortest evaporation time. The evaporation process of hexane droplets mainly follows the constant contact angle evaporation mode, while the evaporation of water droplets mainly follows the constant contact radius evaporation mode. The diffusion model, the Spalding model and the empirical natural convection model were used to calculate the evaporation time. Comparing the three conditions of the liquid gallium surface in ambient air, after HCl vapor treatment and in a glove box, the deviation between the calculated results and the experimental results in the glove box was found to be the largest. The reason for this deviation may be because the existing models are all based on sessile droplet evaporation on rigid substrates, and the flexibility of the liquid metal surface promotes sessile droplet evaporation.