Researcher Awarded Grant for Turbine Coating
The Advanced Research Projects Agency-Energy has recently awarded a $600,000 grant to a professor at the Rolls-Royce University Technology Center on Advanced Material Systems at the University of Virginia for the development of a higher-tolerance turbine engine coatings material.
According to the university, materials science and engineering professor and technology center director Elizabeth J. Opila aims to increase turbine engine materials’ temperature tolerance by 200 degrees Celsius.
“This is an audacious goal for the materials science and engineering community,” Opila said. “In the turbine engine industry, a ten-degree improvement is cause for celebration.”
The phase-one award arrives as part of the Advanced Research Projects Agency’s ULTIMATE program— which stands for ultrahigh temperature impervious materials advancing turbine efficiency. The program targets gas turbine applications in the power generation and aviation industries for the development of ultrahigh temperature materials for gas turbines.
Specifically, ULTIMATE intends to see gas turbines operate continuously with the help of coatings from original stand-alone material test environment temperatures of 1,300 C (2,372 F) to inlet temperatures of 1,800 C (3,272 F) or higher. Environmental barrier coatings and thermal barrier coatings are also within the scope of the program.
Consisting of two separate phases, the first phase of the program involves project teams demonstrating proof of concept of their alloy compositions, coatings and manufacturing processes through modeling and laboratory scale tensile coupon testing of basic properties. In phase two, approved project teams will investigate selected alloy compositions and coatings to evaluate a comprehensive suite of physical, chemical and mechanical properties as well as produce generic small-scale turbine blades to demonstrate manufacturability.
The phases are to be proposed for a maximum of 18-24 months. According to ARPA-E, the development of new ultrahigh temperature materials with compatible coatings and manufacturing technologies could potentially increase gas turbine efficiency up to 7%, reducing the amount of wasted energy and carbon emissions.
To successfully develop ultrahigh temperature materials for gas turbine use in the aviation and power generation industries, ARPA-E has awarded funds to teams working on four mutually dependent research thrusts: alloy development; coatings for the alloys; systems engineering; and test and evaluation of the whole system.
In her research efforts, Opila, alongside her research group, will be focusing on coatings research thrust to develop a coating that will enable a niobium alloy to perform at 1,800 C. Niobium is a high-strength material known to withstand extreme temperatures.
The research team is comprised of individuals from the University of Virginia, Virginia Tech and the Commonwealth Center for Advanced Manufacturing that plans to combine Opila’s expertise in cutting-edge ceramics, alloys and coatings with UVA Engineering’s research strength in materials processing, microstructure, and mechanical property relationships.
To break down other team members’ participation, Prasanna Balachandran, assistant professor of materials science and engineering at UVA, is slated to develop computational models to do the sifting of rare-earth oxides, including all their properties and costs. The university reports that Balachandran’s data-driven approach combines artificial intelligence and quantum mechanics.
Bi-Cheng Zhou, assistant professor of materials science and engineering at UVA, is to ensure that the developed coatings are chemically compatible with the niobium alloy they are designed to protect, in addition to using his expertise in computational thermodynamics and kinetics of materials to reduce oxygen transport.
Patrick E. Hopkins, professor of mechanical and aerospace engineering with courtesy appointments in materials science and engineering and physics, has been tasked with testing the thermal properties of the coatings. From this point, Opila will assess the coatings’ performance in the high-temperature, reactive environments for turbine engines, including the ability to withstand combustion gas and molten debris.
Lastly, two team members are to collaborate on the development of coatings for continued experimentation and performance testing. Carolina Tallon, assistant professor of materials science and engineering at Virginia Tech, will use a slurry process, mixing powders in a liquid to dip-coat the niobium substrate and Joshua Williams, a member of the Surface Engineering Team at the Commonwealth Center for Advanced Manufacturing, will use a conventional air plasma spray technology to make the coatings.
According to the news release, Opila and Tallon previously collaborated on the development of ultrahigh-temperature ceramics. The project was funded by 4-VA, a consortium of eight universities in the Commonwealth of Virginia. Opila also worked with Williams in the past, noting that, “It’s very rewarding that these seed funding projects have paid off in a full-fledged proposal.”
By the end of the research, the team hopes to develop what they are calling, the HERO coating. The newly developed coating will ideally protect the alloy from oxidation by incorporating high-entropy rare-earth oxides. The oxides exhibit two characteristics that are key to meeting the ARPA-E challenge: keeping oxygen out and limiting the buildup of stress within a coating during use because their thermal expansion matches the underlying alloy. The substrate and coating heat up and cool off, or expand and contract, in the same direction and at the same rate.
“ARPA-E has given us an opportunity to do good science and also really good engineering, to solve real-world problems by improving turbine efficiency,” Opila said. The new coating aims to achieve more energy savings, lower carbon emissions and economic benefits not only in the aviation and power generation industries.