Skoltech is researching a number of materials that increase the efficiency of work for covering metal parts of turbines.

Skoltech is researching a number of materials that increase the efficiency of work for covering metal parts of turbines.

Skoltech researchers have proposed a range of ceramic materials to coat the metal parts of turbines to improve performance. According to scientists, if the experimental testing of the materials is successful, gas turbines at power plants will be able to produce more electricity, and jet aircraft will use less fuel. The authors described the method of finding materials for thermal barrier coatings in an article in Physical Review Materials, they told the Habra information service in the Skoltech press service.

New thermal barrier coatings protect the blades of gas turbines of power plants and jet engines of airplanes. The blades themselves are made of strong and corrosion-resistant and high-temperature nickel-based superalloys. However, these parts can soften and melt under the harsh operating conditions of the turbine. The developed protective coating allows to increase the operating temperature of the turbine without harming the blades. According to the researchers, the efficiency in this case increases with temperature.

Artem Ohanov

one of the authors of the study, head of the Material Design Laboratory, professor Skoltech»

“Currently, thermal barrier coatings are made from zirconium dioxide with the addition of yttrium. But if you choose a material with an even lower thermal conductivity, you can get more useful energy from the turbine, he explains. — The search for such materials begins with the identification of promising candidates. Their properties, primarily thermal conductivity, are determined by computational methods. In our article, we list a number of such candidates and will look for new ones.”

A number of requirements are put forward to the material of the thermal barrier coating. It should have a high melting point and low thermal conductivity. Problems are associated with the calculation of thermal conductivity due to the dependence of this property on subtle “anharmonic effects” in the crystal. In addition, when heated, the material must expand in proportion to the superalloy, otherwise the coating will peel off. When heating from room to operating temperature of the turbine, the material should not undergo phase transitions, which would be accompanied by the formation of cracks. Finally, the material must be resistant to dust and oxygen at high temperature and prevent the diffusion of oxygen ions into the superalloy so that oxidation does not occur under the coating.

Majid Zeraati

first author, graduate student at Skoltech

“We calculated all the necessary properties, but it is especially important to calculate the thermal conductivity, and we found how to do it: the method of homogeneous non-equilibrium molecular dynamics turned out to be the most accurate and computationally efficient. This is quite unexpected, because it requires calculations on large systems for a long computing time and collection of large statistics. That is, the calculations are very complicated. But we managed to simplify them by supplementing the method of machine-learned potentials: interactions between atoms were not calculated directly, but predicted by artificial intelligence.”

Scientists from Skoltech brought a number of materials that, in theory, should surpass yttrium-doped zirconium dioxide, which is used in heat-resistant coatings now. Yttrium niobate Y3NbO7, perovskite structures with the formulas BaLaMgTaO6 and BaLaMgNbO6 and seven other materials are named among promising candidates. The team plans to continue the search and find replacements or even new favorites with even more impressive properties.

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