Ricard Aurelien, Restagno Frederic, Jang Yun Hee, Lansac Yves, Raspaud Eric
Laboratoire de Physique des Solides, Université Paris-Saclay, CNRS, 91405, Orsay Cedex, France.
GREMAN UMR 7347, CNRS, INSA CVL, Université de Tours, 37200, Tours, France.
Sci Rep. 2023 Oct 25;13(1):18288. doi: 10.1038/s41598-023-45547-9.
The classical Evans' drop describes a drop of aqueous salt solution, placed on a bulk metal surface where it displays a corrosion pit that grows over time producing further oxide deposits from the metal dissolution. We focus here on the corrosion-induced droplet spreading using iron nanolayers whose semi-transparency allowed us to monitor both iron corrosion propagation and electrolyte droplet behavior by simple optical means. We thus observed that pits grow under the droplet and merge into a corrosion front. This front reached the triple contact line and drove a non radial spreading, until it propagated outside the immobile droplet. Such chemically-active wetting is only observed in the presence of a conductive substrate that provides strong adhesion of the iron nanofilm to the substrate. By revisiting the classic Evan's drop experiment on thick iron film, a weaker corrosion-driven droplet spreading is also identified. These results require further investigations, but they clearly open up new perspectives on substrate wetting by corrosion-like electrochemical reactions at the nanometer scale.
经典的埃文斯液滴描述的是一滴盐水溶液，放置在块状金属表面，在该表面会出现一个腐蚀坑，随着时间的推移，腐蚀坑会不断扩大，金属溶解会产生更多的氧化物沉积物。我们在此关注使用铁纳米层的腐蚀诱导液滴扩展，其半透明性使我们能够通过简单的光学手段监测铁的腐蚀传播和电解质液滴行为。因此，我们观察到液滴下方的坑会不断生长并合并成一个腐蚀前沿。这个前沿到达三相接触线并驱动非径向扩展，直到它传播到静止液滴之外。这种化学活性润湿现象仅在存在导电基底时才会出现，这种基底能使铁纳米膜牢固地附着在基底上。通过重新审视在厚铁膜上进行的经典埃文斯液滴实验，还发现了较弱的腐蚀驱动液滴扩展现象。这些结果需要进一步研究，但它们显然为纳米尺度上类似腐蚀的电化学反应引起的基底润湿开辟了新的视角。
