Waste Not, Want Not

Professor develops new uses for scrap metal

Materials Sciences Professor Kevin Trumble knows that the little things in machining are infinitely the most important. In his case, it’s very little things—specifically, nanoscale structured particle production.

Trumble has collaborated for the past six years with Industrial Engineering Professor Srinivasan Chandrasekar and several students on a new kind of nanoscale structured particle production—taking strengthened machining chips and finding new uses for them.

“Millions and millions of pounds of machining chips are produced every day around the world and most of these have unique internal structures on account of the machining process,” says Trumble. “When you forge a metal or cause it to bend or stretch, it not only changes the shape but becomes stronger in the process. Cutting processes likewise induce severe deformation in the metal chips, which refines the internal grain structure down into the nanometers (billionths of a meter) size scale and thereby greatly increases strength and hardness.”

These tiny pieces of scrap metal, formerly part of the waste stream, are being re-examined by the IE/MSE team. “Something that was formerly just a byproduct could be upcycled and put back into the use-stream at a much higher value than before,” says Trumble, adding that controlling the properties of the chip particles would benefit his other research focus—infiltration processing.

Currently, the standard process for obtaining metal alloy particles is to melt the metal and atomize into small liquid droplets. The process is expensive and the resulting particles lack the work-hardened properties that Trumble studies. The team’s milled chips, on the other hand, can go directly into reinforcements in composite materials and have better properties than the particles made by atomization.

“By infiltrating a compact of chip particles with another metal, composite components that have complex shapes can be produced. It’s like packing marbles in a beaker; they don’t fill space, so you’ve got to infiltrate a liquid into the pores and then solidify the liquid,” Trumble says. The finished product is reinforced and contains the additional properties of the metal chips.

Research in this area will eventually affect industry. Trumble and Chandrasekar, along with co-inventors Dale Compton of Industrial Engineering and Tom Farris of Aeronautics and Astronautics, have three patents issued on producing nanostructured materials by machining, with another pending. A "products to process" patent was issued in November 2007, which covers products made from machining chips.

Despite having several patents under his belt and a wealth of grants, Trumble is true to the basics. He loves working in the lab with his students most of all.

“I probably spend too much time in the lab, but that’s when I feel like I’m having the most fun and doing the best job of teaching,” he says. “I have a philosophy to provide opportunities in lab classes so that students have a chance to make mistakes and figure out what’s going on, rework it again, and see how it can be different from their expectations about the way things behave. I’m most proud of all the students’ work.”

- Rebecca Goldenberg