| Even though low- and high-temperature liquids share some characteristics, they also have important fundamental differences: While the viscosities can be similar, molten metals and oxides have typically 1–2 orders of magnitude larger surface tensions and works of adhesion. In addition, spreading at high temperature is often accompanied of chemical reactions and interdiffusion while most model low temperature systems can be considered non-reactive. The comparison of high- and low-temperature data will help to determine the relative weight of the different physicochemical factors viscosity, solid-liquid interactions, surface tensions, etc. that affect the movement of the liquid front. In this work we will review recent spreading data that suggests that for high-temperature non-reactive systems the mechanism controlling the dynamics of wetting is the friction dissipation at the three-phase line where the substrate, liquid and gas meet. We use the Molecular Kinetic Theory (MKT) to describe this channel of dissipation and compare the experimental results with molecular dynamic simulations that allow us to understand and model the mechanisms that control spreading at the atomic scale. A possible extension to reactive systems is also discussed. |
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