Thermal conductivity study of ZrO2-YO1.5-NbO2.5 TBC

Abstract

The reduction of thermal conductivity provided by the zirconia ceramic for TBC application improves protection of turbine blades during the thermal cycles and the high temperature operations. The TBC is a complex system composed of different layers: a metal substrate, a metallic bond coat, thermally grown oxide (TGO), and ceramic top coat. The present study determined thermal conductivity properties by theoretical calculation of the thermal diffusivity, measured by laser flash technique, at 800 °C and 1250 °C for ZrO2-YO1.5-NbO2.5 (TC) with 14.5, 16.0, and 17.5 mol% equimolar yttria and niobia in zirconia, by CO2 laser on the substrate of titanium. Although microscopy and EDS showed that specific parameters of the laser parameters must be defined to lager thickness of the TBC layers, zirconia co-doped with yttria and niobia promoted a significant reduction of the thermal conductivity by approximately 52 % when compared to zirconia with 7.6 % molar with yttria, currently used in gas turbine engine industry. That TC composition with laser processing could be explored as a candidate thermal insulation material for TBC application.

Keywords

• TBC
• ZrO2-YO1.5-NbO2.5
• Thermal conductivity
• Laser