Reducing Thermal Conductivity of Thermal Barrier Coating Materials With Doping

Abstract

Metal oxides of different valence, ionic radius and mass were incorporated into yttria partially stabilized zirconia (YSZ) in order to investigate the thermal conductivity changes as a result of co-doping. A Mechanical alloying process was used to produce powder blends which were subsequently sintered at 1500°C for 120 hours. The sintered samples were then subjected to detailed examination to determine their thermal conductivities. It was found that, in general, the trivalent oxides Yb₂O₃, Sc₂O₃ and Cr₂O₃, exhibited the most significant effect on reducing the thermal conductivity of 7YSZ (7 wt%Y₂O₃-ZrO₂). This trend was followed by the pentavalent co-doping oxides of Nb₂O₅ and Ta₂O₅ whereas the tetravalent CeO₂co-doped 7YSZ showed a lesser effect.