New 3D printing technology could turn oxidation into an advantage

Professor Changhong Ke receives an NSF grant to explore the potential of incorporating nanotubes into additively manufactured metals.

A major adversary of engineers when designing mechanical systems with metal is oxidation. This chemical reaction leads to the formation of rust and other problems that can affect the efficiency and longevity of devices. Additively manufactured metals, which have enabled advances in fields such as aerospace, marine and automotive, are particularly susceptible to failure in corrosive environments. The 3D printing process increases porosity compared to conventionally manufactured metals.

What if metals could be made stronger through oxidation? This idea is at the center of new research at Binghamton University‘s Thomas J. Watson School of Engineering and Applied Science. Professor Changhong Ke of the Department of Mechanical Engineering is investigating the possibility of incorporating nanotubes into additively manufactured aluminum. He believes that microscopic structures of boron nitride, a compound used in cosmetics, pencil leads and cement for dental fillings, could make the material self-reinforcing under corrosive conditions.

“You can’t avoid oxidation, so we are trying to take advantage of it by turning it into a new, reinforcing mechanism to make the material stronger,” Professor Changhong Ke, a faculty member at Watson College’s Department of Mechanical Engineering, said. “That would be something really amazing. People could try to design the materials to include these sorts of porosities or even purposely introducing structures that can be more easily oxidized because it becomes something beneficial instead of harmful to the material itself.”

The nanotubes that are pulled through the metal are only a few nanometers thick and a few to several hundred micrometers long. To see how the oxidation changes the binding of the nanotubes to the metal – a central theme in the self-reinforcement mechanism – Ke’s team will use a force sensor to pull individual nanotubes from the oxidized metal in a high-resolution scanning electron microscope. This will allow them to observe the processes in real time.

“We designed this as a sandwich structure,” he said. “It’s like a hot dog, with the nanotube as the meat and the metal as the bread.”

The researchers will also test the material on a macroscopic scale to understand how oxidation affects the stiffness, strength and toughness of the nanotube-reinforced metal. Collaborators from the University of Illinois will confirm Ke’s experimental results through computational modeling.

“We’re hoping this will provide a new perspective to the scientific community about how we view metal oxidation in terms of future material design,” he said. “That could change the research landscape for these metal materials, particularly for 3D printed metal. It has so many promising applications in different areas, and it even could revitalize U.S. manufacturing competitiveness.”