A Nature study found that water drops sliding across insulating surfaces damaged a Teflon coating after 3,000 impacts; the coating showed no signs of damage when drops did not slide. Researchers say the drops’ charge can break down the coating, exposing metal to water.
The researchers measured positive charges of 0.2 nanocoulombs on droplets that slid over leaves and about 2 nanocoulombs on those that slid over quartz; they also tested window glass and PVC foam. The process, in which water gains charge while moving across an insulating surface, is called slide electrification.
The authors say charged droplets can also occur in clouds, thunderstorms, ocean waves and waterfalls. A possible solution discussed in the article is a coating that gives charge a path to dissipate, rather than simply making the layer tougher; such designs could help protect bridges, pipelines, vehicles and cultural sites.
