Going Heavy Metal

Tucked away in the subbasement of Pitt’s Benedum Hall, past the Panther Racing parts spilling into hallways, you’ll find a giant machine that looks like a cross between a car garage and the entry port of a sci-fi spaceship. It’s a state-of-the-art 3D printer for metal – the Gefertec arc605.

For producing big, specialized metal parts, the machine is unbeatable, said Albert To, William Kepler Whiteford Professor and an expert on 3D printing.

“Even on the order of tens of parts, this is very advantageous,” he said. “And if you want to include some complexity, then you can’t do it any other way than 3D printing.”

The printer makes use of welding, melting wire made from metals like stainless steel, titanium and aluminum alloys and depositing it layer by layer. Previous metal 3D printers in the lab using lasers and metal powder could lay down a few hundred grams an hour; this one is an order of magnitude faster.

That makes the Gefertec printer ideal for producing larger parts that would normally have to be casted and tooled, an expensive approach that’s often not practical for manufacturing small-batch, specialty pieces. One of To’s first projects, for instance, is to make a three-footlong bridge joint for the U.S. Army that’s no longer manufactured.

While the technology has been around for decades, only in the past several years has it become reliable enough to gain widespread notice. “All of a sudden, there’s a very high interest in industry,” including in aerospace, nuclear power and oil and gas, To said.

The machine’s advanced software and “fiveaxis” capabilities where pieces can be rotated and tilted during printing means it can be used to create complex metal parts. But there are still plenty of kinks to work out. For instance, metals warp as they heat and cool, a process that To is using the new printer to study with funding from the U.S. Army and the Department of Energy.

Xavier Jimenez, a third-year PhD student in To’s lab, is developing a process to 3D print using a new type of high-strength aluminum that has potential applications in aerospace but tends to crack when welded.

“You have to tune all these different parameters to figure out what will produce the best-quality weld,” Jimenez said. “Every material behaves a little differently.”

Jimenez came to Pitt in part because he wanted to work with the Gefertec arc605, but COVID-19 threw a wrench in the gears, and the printer took three years to make its way to Pitt. The machine is larger than some studio apartments, and when it did arrive it had to be dropped into the lab piece-by-piece via crane and then assembled.

Having made it through the installation, the team is now in the process of testing parameters for the 3D printing of different metals. By testing the approach for different metals, then using X-rays and testing material properties, they can start to model how the process affects a part – from visible warping to changes to the microscopic structure of the material.

Further out, To is collaborating with colleagues to create smart components where fiber-optic cables are embedded in 3D-printed metal parts to sense the temperature and deformation of the part.

“It was a lot of work to get all the pieces together to get the machine working,” Jimenez said. “We’re very happy that it’s here.”

– Patrick Monahan, photography by Aimee Obidzinski. Originally published in Pittwire

Getting It to Stick: Grabbing CO2 Out of the Air

Direct air capture may be key to saving Earth from the effects of climate change, but there is a catch: It’s hard to do.

Direct air capture (DAC) technologies are designed to remove carbon dioxide from the air, although there is still a lot of room for improvement in DAC materials. Other molecules in the air, especially water, are in much higher concentrations than carbon dioxide, or CO2 They compete, and ultimately, carbon dioxide isn’t caught – at least in high quantities.

“If materials are good at grabbing carbon dioxide, they’re usually good at grabbing multiple gases,” explained Katherine Hornbostel, assistant professor of mechanical engineering and materials science. “It’s really hard to tune these materials to grab carbon dioxide but nothing else, and that’s what this research is focused on.”

Hornbostel is joined by co-investigators

Nathaniel Rosi, a Pitt chemistry professor with a secondary appointment in the Swanson School, and Christopher E. Wilmer, associate professor of chemical and petroleum engineering and William Kepler Whiteford Faculty Fellow. Janice Steckel, a research scientist at the National Energy Technology Laboratory, and graduate students Paul Boone, Austin Lieber, and Yiwen He will also be working on the project. Together, they published a journal paper for the Royal Society of Chemistry about creating new metalorganic frameworks, or MOFs, designed to capture just carbon dioxide.

MOFs, a research focus in Wilmer’s lab, are highly regarded for their ability to utilize porous membranes to capture large volumes of gasses and can be designed via computational modeling rather than traditional trial-and-error.

The MOF would have a core-shell design, meaning carbon dioxide would be trapped in the core, while the shell is able to block other gasses, specifically water. The shell and the core would be made from different MOF materials, with the shell MOF designed to slow down water and the core MOF designed to bind CO2

Ones to Watch: Asher Hancock

Asher Hancock has been interested in flight for as long as he can remember.

But there was one moment when he knew he was hooked.

“I went to NASA’s Kennedy Space Flight Center, down in Florida. Standing underneath the Saturn V rocket they have there – it was an engineering marvel,” he said. “Since then, I knew I wanted to work on something related to space or flight.”

A 2022 graduate of Pitt’s Swanson School of Engineering who majored in mechanical engineering with minors in computer science and mathematics, Hancock spent the past few years rocketing to new heights himself: first with a 2021 Goldwater Scholarship and now a graduate fellowship from the National Science Foundation and one of the most prestigious awards available to students in the U.S. –a Churchill Scholarship.

The scholarship funds a year of study at the University of Cambridge in the U.K., supporting students in science, math, and engineering. Hancock, one of 18 awardees this year, is the fifth Pitt student to be honored by the Winston Churchill Foundation of the United States.

“The Churchill Scholarship is one of the most selective science scholarships in the country; it is aimed almost exclusively at emerging research scientists who are already on the path to completing high-level doctoral research,” said Aidan Beatty, a scholar-mentor in the University Honors College who advised Hancock. “Asher is clearly on that kind of ambitious and upward-moving trajectory.”

In his research, Hancock is interested in developing better autonomous systems by combining two different fields: machine learning and control theory. He explains the latter field with the example of a car’s cruise control.