In this work a model for the mechanism of dropwise condensation on ion implanted metallic surfaces is proposed. Considering experimental results for respective surfaces, the model is based on droplet nucleation and growth on preferably wetted, elevated precipitates, resulting in short-term steam entrapment after droplet coalescence. According to wetting theory this transition state yields increased macroscopic contact angles enabling dropwise condensation. Open condensation phenomena like enlarging dropwise condensation areas in spite of increasing condensation rate become comprehensible by our approach. Furthermore, the model points out that contact angles and surface free energies measured under ambient air conditions are not usable for predicting the condensation form of steam on the modified surfaces. Although the suggested microscopic mechanism cannot be directly proved by experiment, its capability of explaining experimental observations colliding with previous theoretical approaches supports its validity. The results also reveal that dropwise condensation of steam can originate from microscopically different mechanisms.

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