UVA Materials Science and Engineering Ph.D. student’s research is aimed at making jet engines more durable.

As an undergraduate at Radford University, Rebekah Webster found the ideal way to combine her major in chemistry with her interest in art. She landed an internship in the Objects Conservation Department at the Metropolitan Museum of Art in New York.

Webster was aware that chemical changes in some of the pigments artists used caused the colors of their canvases to fade or change over time — for instance, the flowers in Vincent Van Gogh’s Roses at the Met were originally pink, not white — and she wanted to learn more about how curators traced these changes.

“This was one of the best things I have ever done in my life,” Webster said, and, as it turned out, one of the most clarifying. She decided she was more interested in finding out why artwork degraded. Gaining a better understanding of corrosion processes, no matter the context, became her goal for graduate study — and one that she is satisfying in Professor Elizabeth Opila’s lab in the University of Virginia Department of Materials Science and Engineering.

Webster’s research on new environmental barrier coatings designs for silicon-carbide-based ceramic matrix composites is sponsored by Rolls-Royce. UVA is home to one of three Rolls-Royce University Technology Centers in North America developing technologies for aerospace and advanced manufacturing, and Opila is the director of the UVA center.

Right now, ceramic matrix composites’ lighter weight and greater heat tolerance makes them leading replacement materials for the nickel-based superalloys used in jet engines. The hotter the combustion, the more efficient the engine.

Environmental barrier coatings protect ceramic matrix composites from degradation from water vapor and particulate matter produced during combustion. The challenge is to design environmental barrier coatings that resist corrosion caused by sand, dust and even volcanic ash sucked into the engine.

These contaminants are referred to collectively as calcium magnesium alumino-silicate, which melts in the engines, leading to penetration and failure of their environmental barrier coatings. “Our goal is to devise a mitigating strategy,” Webster said.

Her prime coating candidates are rare earth silicates, materials that can cause the melted contaminants to crystalize on the barrier coating, essentially sealing the surface. She is experimenting with the chemistry and microstructure of these materials and characterizing their behavior in contact with contaminants of varying composition.

Rolls-Royce is supplying a viscometer that she will use this year to determine the viscosity of molten calcium magnesium alumino-silicate with varying compositions and to determine if this characteristic has an effect on the infiltration of environmental barrier coatings.

Webster has benefited from UVA’s membership in the Rolls-Royce University Technology Center network in other ways. Along with fellow graduate students supported by the company, she was invited to attend Ph.D. Day at Rolls-Royce’s Indianapolis campus.

“We met Rolls-Royce employees, presented our research and got to know Rolls-Royce-funded students from other universities,” Webster said. “It was a great opportunity for career development and networking."