Aircraft and power plants: Researchers develop coating for more efficient and environmentally friendly turbines.
Turbines power aircraft and are used in different industry applications, such as energy generation in power plants. The rule is: the hotter the temperature at which fuel is burned, the more efficiently heat is converted into electricity or thrust. Reduced fuel consumption decreases both emissions and operating costs. However, current materials can no longer be further optimized in some cases. New materials capable of withstanding even higher temperatures are needed, according to the German Aerospace Center. With support from the U.S. Department of Energy, a research team led by the University of Virginia (UVA) has now developed a way for turbine engines to operate at higher temperatures.
The focus was on further developing a specific class of materials: alloys made of so-called refractory metals (from Latin “refractarius” = resistant, stubborn) like titanium, hafnium, and vanadium, known for their durability and heat resistance. However, according to the research team, their oxidation resistance is insufficient, so coatings must protect them. With the materials previously used for this purpose, such as silicon-based compounds, the limit for further performance increases has been reached, according to the research published in the journal Scripta Materialia.
Rare Earths: Strong Natural Protective Effect
To address this issue, the researchers experimented with oxides of rare earth elements like yttrium, erbium, and ytterbium, which have strong natural protective properties against heat. To predict the best combinations and improve performance, they used computer simulations and machine learning, a form of artificial intelligence. The materials thus developed were then tested for durability and physical properties, including with lasers.
The result was a highly efficient coating that requires only a single layer to protect the underlying substrate. It acts as a barrier against gases that form at such high temperatures and can damage turbine blades, explains lead researcher Elizabeth J. Opila. Further tests and optimizations must now follow to expand this important advancement in turbine engine technology. Ultimately, says Opila, greater efficiency in this field would benefit both the energy and aviation industries, as well as reduce environmental impact and lower costs for consumers.
How Critical Raw Materials Propel Aviation: In April, we reported on another promising alloy for the engines of the future, which involves the technology metals niobium, tantalum, titanium, and hafnium. Another technology metal, gallium, could help speed up aircraft de-icing, potentially reducing winter disruptions at airports.
photo: istock/frankpeters