Structural characterisation of thermal barrier coatings deposited using electrostatic spray assisted vapour deposition method

Gas turbine engines provide one of the harshest environments for engineering components today. Thermal barrier coatings (TBCs) such as 8wt.% Y2O3–ZrO2 (YSZ) are able to protect the blades and can lead to further increases in operating temperature by providing an effective thermal barrier on the blades. YSZ coatings were deposited using a novel and cost-effective electrostatic spray-assisted vapour deposition (ESAVD) technique. This method involves spraying atomised precursor droplets across an electric field, where they undergo decomposition and/or chemical reactions in the vapour phase near the vicinity of the heated substrate. A solution containing zirconium and yttrium alkoxide precursors was used for the deposition of YSZ films. The coatings were characterised using a combination of scanning electron microscopy, X-ray diffraction (XRD) and Raman spectroscopy. Thick and uniform YSZ films with columnar growth features were successfully deposited using the ESAVD method. The Raman investigations showed the presence of carbon in the as-deposited coatings. However, the carbon was removed when the YSZ coating was heat-treated at 1000°C for 2 h to improve the adhesion of the TBC coating to the bond coat.