A research team at the University of Virginia developed protective coatings that enable turbine engines to run at higher temperatures. According to lead researcher, professor, and chair of the Department of Materials Science and Engineering, Elizabeth J. Opila, “Hotter engines are more efficient. You get more work output per heat input at higher temperatures. The potential benefits drive interest in coatings that act as a barrier against the reactive gases produced by combustion at these high temperatures that can damage turbine blades.” The team published its findings in Scripta Materialia.
Two primary material systems are currently used in the hot section of turbine engines:
- Coated nickel-based superalloys that tolerate up to approximately 2,200°F, short of the DOE’s goal of nearly 3,300°F.
- Ceramic composites using several coating layers to protect against degradation from oxidation, which are limited by one layer of silicon, which melts at 2,577°F.
The researchers focused on a material option called refractory metal alloys, which had been previously studied but abandoned due to poor oxidation resistance. Experimenting with rare earth oxides, they came up with one do-it-all coating. They created and tested new combinations of rare earth elements, including yttrium, erbium, and ytterbium. They worked with UVA associate professors Bi-Cheng Zhou and Prasanna Balachandran, who specialized in computer simulations and machine learning. They also partnered with UVA Professor Patrick Hopkins’ ExSiTE Lab, which specializes in using lasers to measure heat resistance and material strength.
The coatings were applied to alloys using two standard manufacturing methods: heating the material to a molten state before spraying it on the surface and applying it as a liquid mixture that dries and hardens.
“Reducing fuel consumption and emissions while improving engine performance is not only good for industries like energy and aviation,” Opila said. “It also means a cleaner environment and lower costs for everyday consumers.“
