As a rule, gas turbine blades are made of super alloys based on nickel, which are resistant to corrosion. However, even these materials may melt when exposed to high temperatures during fuel combustion. Protective coating is applied on the blades to provide additional protection allowing for increasing the operating temperature of the turbine saving the blades’ components from softening and melting.
Yttrium and zirconium dioxide with high melting temperature and low thermal conductivity are the main components of feedstock for such thermal barrier coating. Using mathematical calculations scientists try to find even more efficient analogues meeting three additional criteria: when heated, the material must expand commensurate with the super alloy, otherwise the coating may peel off; when exposed to significant rise of temperature, the material should not undergo phase transformation accompanied by fracturing; and finally, it should be resistant to dust and oxygen impact under high temperature and should prevent the oxygen ions diffusion into the super alloy, so that there is no oxidation reaction under the coating.
To identify the properties of the sought-for material, the researchers from SkolTech used the method of homogeneous non-equilibrium molecular dynamics. “This is quite unexpected, because this method requires calculations in very big systems during very long computing time and collecting big amounts of statistics. The computation are very complex. However, we managed to simplify them by adding machine-trained facilities to the method: interactions between the atoms were not calculated directly, but were forecasted by artificial intellect”, SkolTech is citing Madjid Zeraati, the post-graduate student.
The calculations showed that yttrium niobate (Y3NbO7) usually used in medical and industrial X-ray radiography and perovskite-type structures (BaLaMgTaO6 and BaLaMgNbO6) can be used for manufacturing thermal barrier coating. According to the researchers, these materials are to demonstrate better performance than zirconium dioxide doped with yttrium.
