Water droplets can act like tiny dancers on a surface, picking up electrical charges as they slide. When these charged drops land on materials with certain properties, including metals, they can transfer their charge. Over time, this process can lead to corrosion, even if the material has a protective coating. Scientists reported this discovery in Nature on August 26.
This effect might happen in various places where water moves, like clouds, thunderstorms, or waterfalls. Understanding this could help create better ways to prevent corrosion in cars, buildings, and historical sites. Stefan Weber, a physicist at the University of Stuttgart, says this research is an important step forward. Earlier studies showed that sliding water picks up charges, but linking it directly to corrosion is new.
In experiments, water drops slid on surfaces like leaves and glass. When they landed on copper coated with Teflon, they caused visible damage under a microscope. Corrosion costs are huge—estimates suggest global losses in the trillions each year. For example, the U.S. automotive industry lost over $30 billion in 1999 due to rust and other corrosion.
Scientists once thought water damage was mainly from physical impact or tiny amounts of acid in the droplets. But when Zhongyuan Ni, a physicist at the Max Planck Institute, let his experiment run longer, he noticed signs of damage after many drops. This led him and his team to explore how electric charges might play a role in corrosion.
This new understanding could help develop better ways to protect materials from damage caused by water.