Infrared radiative properties of EB-PVD thermal barrier coatings

In the present paper the infrared radiative properties of electron beam physical deposition (EB-PVD) partially yttria stabilized zirconia (YSZ) thermal barrier coatings (TBCs) have been studied in combination with experimental measurement and theoretical model. The method of Finite-Difference-Time-Domain (FDTD) is employed to investigate the infrared spectral reflectance and transmittance of TBCs with various microstructural parameters and validated by a following experiment. The infrared radiation transfer mechanisms inside the coatings are explored and examined in detail. The results indicate that distinctive micro-nanostructures of EB-PVD coatings have important effects on its radiative performance, and the infrared spectral reflectance and transmittance of coatings are highly affected by the primary columnar morphology and pore architectures, such as intercolumnar gaps, feathery striation and closed globular pores. Further research suggests that scattering effects caused by different microstructures can greatly affect radiative transfer across the coatings. By optimizing the microstructure of coatings properly to enhance its backscattering effects, it can effectively increase the spectral reflectance and reduce the spectral transmittance, thereby reducing the radiation heat flows and providing a better thermal protection for the metallic substrate.