Grad Student Sharon Uwanyuze Wins a Rare Scholarship for Her Work on Refractory Ceramics

Sharon meets George Gower (President of Refractory Minerals Inc.), to discuss the raw materials on the banner which his company supplies.

Sharon meets George Gower (President of Refractory Minerals Inc.), to discuss the raw materials on the banner which his company supplies.

Sharon Uwanyuze, a Ph.D. candidate in Assistant Professor Stefan Schaffoener’s lab, was one of three students nationwide who received The Refractories Institute Award at the 2019 Fall Institute Meeting in Columbus, Ohio November 6-7.

The award includes a one-time grant of $5,000. They are given based on academic merit and the student’s interest and experience in the field of refractories, according to The Refractories Institute (TRI) announcement.

“My thesis is closely tied to TRI’s mission: advancing and supporting students who want to further their knowledge in refractory ceramics and then apply that in industry,” Sharon said. “They are called ‘refractories’ because they have great high temperature performance.”

Currently, Sharon’s research focuses on materials processing of refractory ceramics for titanium metallurgy, with an emphasis on corrosion and mechanical behavior at high temperatures. When she was looking at graduate programs, Sharon spoke to three professors at UConn’s MSE department. One of them was Stefan Schaffoener, who works with ceramics and composites focusing on corrosion, and high-temperature materials processing for aerospace applications.

“He works at the interface of ceramics and metals during titanium alloy casting,” Sharon said. “At high temperatures, molten titanium can oxidize rapidly.” This is a problem for Schaffoener’s lab group, because current ceramic casting molds do not sufficiently limit oxidation. Once titanium picks up more than 0.2 wt% oxygen, the toughness at the metal’s surface is drastically reduced and it will no longer be suitable for most aerospace applications. Therefore, this surface layer is currently milled away mechanically or chemically. However, if researchers could sufficiently understand and control the melting process and the refractory ceramic composition, this oxidation problem could be mitigated.   

“That challenge initiated the research I’m working on. I synthesize the materials of the ceramic casting molds that titanium is melted in and analyze their properties and performance,” Sharon said. For instance, if they use a ceramic mold that forms a barrier between titanium and the ceramic material itself, that prevents further diffusion of oxygen from the mold into titanium, and vice versa. While zirconium oxide-based molds work well with other metals, zirconium  tends to diffuse into highly reactive metals like titanium alloys and contaminate the metal.

“We’re now working on other ceramic materials such as calcium zirconate. Zirconia has a high melting temperature and excellent stability. By doping it with other elements we can make it even more stable with titanium,” Sharon said.

Earlier this year, Sharon completed a summer internship at Oak Ridge National Laboratory (ORNL), working on ceramic matrix composites for energy-producing (nuclear) applications. She used her knowledge of ceramic processing and properties to work alongside Dr. Stephen Raiman, a Research & Development Associate in Corrosion Science at ORNL.

But her path to the TRI scholarship wasn’t always this clear.

“It was exciting to win. I had tried to apply for that scholarship as an undergraduate while working in an Advanced Ceramics laboratory, but I didn’t get it. Now they can see I’m truly focused on refractory ceramics.”  

As an undergraduate at the University of Alabama at Birmingham, Sharon was a research assistant in an advanced ceramics lab, which was unique in their metal-focused program. She worked on synthesizing yttria-stabilized zirconia for ceramic applications.

“While working as an undergrad research assistant, I was encouraged by my advisor to pursue grad school because I was research-driven and had good grades. It was great advice, and I like to speak to undergrads and show them that grad school is a great possibility,” Sharon said.

She had the chance to speak directly to undergraduates when she participated on a panel at UConn’s chapter of the National Society of Black Engineers (NSBE) in October. 

“It’s important to me because I was shocked to learn that on average, less than 5 percent of Engineering bachelor’s degrees go to black students. Our undergraduate program is very diverse, but I think a lot of students may think graduate school is not an option, especially if they’re first-generation college students.”

Sharon is the first in her family to do a Ph.D., and feels that UConn is a great institution for her. “Here, we have a lot of library resources, top-notch equipment, and a whole building dedicated to characterization and microscopy,” she said, referring to the UConn Tech Park. “So we want to encourage undergraduates to look into that too.”

Sharon added that the professors in the MSE department are very approachable and willing to mentor students. “In Dr. Schaffoener’s group, we currently have three undergraduate research assistants, one of whom I help mentor. I was once in this position as an undergrad, and having research mentors is truly a phenomenal resource,” she said.

Sharon plans to use the grant money to invest in a high-power desktop computer for her lab, so she can improve her studying and experiments.

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