Sometimes, a simple decision to try something unconventional can lead to a significant discovery.A well-known method of making heat sinks for electronic devices is a process called sintering, in which powdered metal is formed into a desired shape and then heated in a vacuum to bind the particles together. But in a recent experiment, some students tried sintering copper particles in air and got a big surprise.
Instead of the expected solid metal shape, what they found was a mass of particles that had grown long whiskers of oxidized copper. “It was sort of serendipitous,” says Kripa Varanasi, d’Arbeloff Assistant Professor of Mechanical Engineering at MIT. “We got this crazy stuff, particles covered in nanowires,” he says.
The resulting process could turn out to be an important new method for manufacturing structures that span a range of sizes down to a few nanometers (billionths of a meter) in size. “You go in one step from solid spherical powder to very complex structures,” says Christopher Love, a mechanical engineering graduate student who is lead author on the paper. “The process is very simple, and the structures are durable,” he says. These new structures could be used for managing the flow of heat in various applications ranging from powerplants to the cooling of electronics.