Multilayer Thermal Barrier Coating prepared by EB-PVD process and its structure property correlation

Abstract

The present work discusses our findings on development of nanostructured Yttria Stabilized Zirconia (YSZ), Lanthanum Zirconate (LZ) coatings, bond coat (NiCrAl) and their Multilayer coatings by electron beam evaporation for potential thermal barrier applications. The YSZ and LZ coatings were found to have cubic FCC phase and amorphous phase respectively. The grain sizes were found to be less than 50 nm in all the layers as observed by AFM and FEG SEM. A detailed cross sectional microstructure and compo-sitional analysis revealed the presence of different layer near to stoichiometry. X-ray diffraction confirmed the formation of desired phases in different layers. The cry-stallite sizes were found to be less than 50 nm, as esti-mated by X-ray diffraction peaks by Debye Sherrer equat-ion. Nanoindentation studies were carried out for study-ing the mechanical behavior of the single and multilayered coatings.Thermal diffusivity was assessed for YSZ coatings.