Thermal conductivity study of zirconia co-doped with yttria and niobia for TBC application

Reference Presenter Authors
14-086 Renata Jesuina Takahashi Takahashi, R.J.(Universidade Federal de São Paulo); Assis, J.M.(Instituto de Aeronáutica e Espaço); Neto, F.P.(Instituto de Aeronáutica e Espaço); Reis, D.A.(Universidade Federal de São Paulo); The topcoat in TBC plays a role the protection for thermal cycles and the metallic material applied for working in high temperature of the turbine blades. The present study investigated the ZrO2-Y2O3-Nb2O5 system for a potential protection and reduced thermal conductivity when compared with zirconia-yttria coating. The TBC were composted with the Ti-6Al-4V (metallic substrate), NiCrAlY (bond coat), thermally grown oxide (TGO) and the ceramic topcoat. The zirconia ceramic was co-doped with yttria and niobia with 14.5, 16.0 and 17.5 mol %. The deposition process the bond coat and power ceramic were by CO2 laser and the TGO was forming by vacuum thermal treatment in 1100 °C. The thermal conductivity properties were determinedby theoretical calculating from thermal diffusivity experiment result in 800 and 1250 °C. The samples were analyzed by microscopy and EDS for the morphology analysis and chemical analysis of the layers obtained. The SEM / EDS analysis showed was necessary for studies more specific of laser parameters for layer adhesion and non-melting for those materials. The ceramic layers were had promoted a significant reduction of thermal conductivity of which the zirconia ceramic with 16.0 mol % of yttria and niobia reduced in approximately 70 % when compared zirconia with 7.6 mol % with yttria.