THERMALLY OXIDIZED ZIRCONIUM NANOCRYSTALLINE THERMAL BARRIER COATING DEPOSITED BY EB-PVD

Abstract

Zirconium oxide nanocrystalline deposited on the bound coat of thermal barrier coating TBC by an electron beam physical vapour deposition EB-PVD was thermally oxidized at oxygen ambient after deposition process within 1073 K resulting in Zirconium oxide top layer with various stoichiometries. Intermetallic alloys based on γ -TiAl due to offer low density over conventional Ni supper alloy was used as substrate. Field emission scanning electron microscopy FESEM observation of the deposited specimens at three different oxygen partial pressure during coating indicate the appropriate adhesion of ZrO2 when thermally grown oxide TGO had been taken place as buffer layer between top coat and bound coat which are contain 8mol% Yttria Stabilized Zirconia (YSZ) and MCrAlY respectively. Energy dispersive spectrometer EDS to determine the composition of present element after deposition was employed. XRD analysis of the ex situ TBC components revealed the phases formed at different oxygen partial pressure. The present of this intermediate TGO layer was confirmed by observation of AL2O3 and yttrium aluminates (YAlO3 and/or Y3Al5O12) phases in the XRD patterns. Al2O3 provides an effective diffusion barrier that protects the underlying metal from deleterious oxidation during thermally oxidizing the zirconium. Using rapid thermal processing RTP analysis data, the effective oxidation temperature on the stoichiometry of zirconium oxide and thickness of grown were investigated therewith, the crystallization of zirconium oxide films was initiated at about 480 K and was almost completed at 525 K. Micro indentation test was accomplished to qualifying the adhesion of Zirconium oxide nanocrystalline and the interfacial of bond coat.