Microscopic insights into the effect of surface wettability on melt infiltration in porous media: Experimental and simulation studies

The influence of particle surface wettability on melt infiltration in porous media is investigated by combining both experiments and simulations. Melt infiltration experiments are conducted by introducing molten tin-bismuth eutectic alloy (Sn-Bi) into preheated particle beds composed of 1.5 mm spherical particles of either copper (Cu) or tin-coated Cu (Sn-coated Cu). After solidification, the distribution of Sn-Bi within the particle beds is analyzed using scanning electron microscopy (SEM). To complement the experimental findings, three-dimensional (3D) pore-scale numerical simulations are carried out, allowing a direct comparison between the simulated melt distribution and SEM observations. The SEM analysis of the composite of the particle bed infiltrated by Sn-Bi reveals that at temperatures below 150 °C, the Cu particles exhibit poor wettability by Sn-Bi melt, characterized by a local contact angle of around 145°, whereas Sn-coated particles demonstrate enhanced wettability with a contact angle of approximately 65°. These observations are also supported by the 3D simulations, which show that higher wettability leads to smoother melt fronts and more pervasive infiltration, while lower wettability results in restricted melt infiltration. The findings highlight the critical role of particle surface wettability in governing melt infiltration, which is crucial for understanding the melt relocation behaviors in safety-critical systems and optimizing materials processing.