Experimental study on the spreading behavior of oxidized liquid metal droplet impacting a solid surface under vertical magnetic field

GaInSn liquid metal alloys in room temperature have a fantastic application prospect, due to their low melt point, high thermal conductivity (16.5 W/m−1 · K−1), and other attractive material properties. However, these alloys are easily oxidized in the air, and their wetting characteristics are changed. In this study, the spreading process of oxidized GaInSn droplets impacting a solid substrate was investigated using a high-speed camera. The spreading characteristics of the oxidized GaInSn droplet post-impact were examined using a phenomenological method. The spreading parameter, denoted as β = D/D0, was measured as a function of the Weber number. Additionally, a vertical magnetic field was applied to study its effect on the dimensionless maximum spreading diameter, which can provide reference for precise control applications. The results indicated that the oxidation layer causes the droplet to cease oscillating rapidly post-impact due to a strong adhesive force between the liquid and solid surface. The vertical magnetic field was found to inhibit the spreading process dramatically. An empirical formula for the maximum spreading factor, βmax, in relation to the Weber number was obtained, revealing a power of 2/5.