Pipes, tools, and surfaces in contact with salt water usually have a corrosive layer of salt and other dissolved minerals that must be scraped off or washed off. MIT engineers have taught metal surfaces to self-clean, even water pipes. The new method makes minerals so easy to remove that they just fall off on their own.
Typically, when a drop of saltwater adheres to a surface, the mineral forms a spherical shape as it evaporates. Thus, the crystal contacts the surface over a large area. Ultimately, the metals become covered with a salt crust over the entire surface, which is difficult to remove.
For the new study, the MIT team explored ways to alter this crystallization process by “tweaking” the surfaces themselves. Eventually, they stumbled upon an intriguing phenomenon that they had not seen before.
If the surface is hydrophobic (water-repellent), heated, and has a certain nano-size texture with small protrusions, the salt crystallizes in a unique way. A ball is formed, and soon strange structures similar to legs begin to sprout under it, pushing it up. They eventually grow for so long that they can no longer support the weight and the crystal breaks off.
Scientists argue that the properties and texture of a surface with specified parameters can be easily transferred to various objects by etching or coating methods. This makes it easy to scale and integrate development into existing infrastructure. The technology is useful for desalination plants, water distribution pipes, geothermal wells and almost everywhere where polluted water is regularly used.