Microstructural, mechanical, and electrical characteristics of alumina-reinforced ytterbia-stabilized cubic zirconia-based composites

Al₂O₃-dispersed Yb₂O₃-stabilized cubic-ZrO₂ (YbSZ) composites are fabricated by pressureless sintering of composite powders to obtain fine and homogeneous microstructures by the solution chemistry route. Al₂O₃ particles are deposited on ZrO₂ powders by the precipitation of aluminum nitrate followed by calcination in air. The sinterability of the composites was affected by the calcination temperature. Microstructures of the sintered bodies are dependent on the Al₂O₃ content. For the 5 vol% Al₂O₃-dispersed composite, fine Al₂O₃ particles were mainly located inside the grains of zirconia, whereas relatively large Al₂O₃ particles almost dispersed at the grain boundaries when the Al₂O₃ content was increased. The grain growth of YbSZ was suppressed by the Al₂O₃ addition, and the refinement of the matrix grain improved the fracture strength of YbSZ. The YbSZ and YbSZ/Al₂O₃ composites exhibited almost similar ionic conductivity at high temperatures of around 1000 °C.