80 / 2021-06-30 14:52:32

Effect of Gd2O3 and Yb2O3 Doping on the Microstructure and Properties of ZrO2

ceramics,doping,thermal conductivity,hardness,modulus,fracture toughness

Gd and Yb elements have high chemical stability, which can stabilize the solid solution in ZrO₂. Gd₂O₃ and Yb₂O₃ have high melting points, and good oxidation resistance under extreme environments, stable chemical properties. Therefore, Gd₂O₃ and Yb₂O₃ were added to ZrO₂ to stabilize oxides, improve the high temperature stability and effectively decrease the thermal conductivity at high temperature. In this work, 5% Yb₂O₃ and 5%, 10%, 15% Gd₂O₃ were doped in nano-ZrO₂ powder by weight percentage as thermal barrier coating materials, and sintered at 1650℃ for 6h, 12h, 24h. The effects of Gd₂O₃ and Yb₂O₃ doping on the structure, density, thermal conductivity, hardness and fracture toughness of ZrO₂ bulk materials were investigated. It was found that the density of the sintered bulk reached 96.89% at 1650℃ for 24h. With the increase of Gd₂O₃ addition, the thermal conductivity of the bulk decreased to the lowest thermal conductivity of 0.43W/(m•k) at 1100℃ with 15wt% Gd₂O₃ addition. Meanwhile, its hardness, elastic modulus fracture toughness increased to 15.06 GPa, 189.60 GPa, 7.822MPa•m^0.5, respectively. The doping Gd₂O₃ and Yb₂O₃ in ZrO₂ could not only effectively reduce the thermal conductivity but also improve the mechanical properties, which would contribute to improve the thermal barrier coatings’ performances furtherly.