Adsorption-pressure and geometric effects on the surface tension of nanobubbles in molten metals

JX Chen and MH Lv and ZJ Gao and MM Liu and G Li and BL Liu and CZ Gu and DJ Singh and WT Zheng and XF Fan, PHYSICS OF FLUIDS, 37, 077158 (2025).

DOI: 10.1063/5.0277385

The surface tension of nanobubbles in molten metals is a critical physical parameter that governs bubble dynamics and has significant implications for metal smelting, casting, and laser additive manufacturing processes. However, the current understanding of nanobubbles within molten metals remains limited. Here, using molecular dynamics simulations, we studied stationary nanobubbles in molten metals, focusing on understanding and characterizing the surface tension and its role. The curvature radius of the bubble, determined by the position of the superficial density peak, is introduced to capture the surface of tension. The result is an increase in surface tension with a decrease in bubble size. The impact of high internal Laplace pressure within the bubble on the surrounding molten metal surface layer is found to be very significant. This underscores the extreme pressure conditions inside nanoscale bubbles that lead to significant surface interactions even with inert atoms such as helium. The surface tension of nanobubble is found to be determined by the combination of adsorption-pressure effect and geometric effect which leads to high internal pressure. Furthermore, the intrinsic surface tension follows a universal scaling law. These provide atomic insights into the surface behavior of nanobubbles within molten metal, which facilitates in controlling the bubbles in metal liquids.

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