Wetting and Spreading of Liquid Metals Through Open Micro Grooves and Surface Alterations

Surface tension driven flows of micro layers of complex liquids over substrates under reactive wetting conditions are greatly influenced by interface interactions and topography of surface alterations. For example, understanding of spreading of molten metals over metal substrates with complex topography may be interpreted as spreading over multiple connected networks of open micro channels. Hence, understanding of the kinetics of wetting and spreading of such reactive systems through micro channels is of a key interest. This keynote lecture will provide an overview of wetting/spreading phenomena related to migration of the molten metal micro layer over smooth, rough, and/or well-organized-topography surfaces, such as micro channels. Systems involving a liquid metal medium temperature range (Al-Si over Al), and a low temperature range (Pb-Sn and Ag-Sn over Cu and Cu-Sn) have been considered. Kinetics data involving triple line movement and its modeling will be supported by real-time in situ visualizations. Targeted applications of these fundamental studies involve art of brazing of compact aluminum heat exchangers for HVAC&R, thermal management for aerospace, and soldering processes (in particular lead-free) for electronics industries.