Self-toughening behavior of nano yttria partially stabilized hafnia ceramics

Sandwich structure of cubic (C) phase/monoclinic (M) phase/C phase was formed in 8% mol Y 2 O 3 partially stabilized HfO 2 (Hf 0.92 Y 0.08 O 1.96 , YSH8) samples which were produced by sintering of YSH8 green body cold pressed from nano-powders of C phase at 1500 °C. The geometry of the sandwich structure was approximately tailored by controlling the sintering time. The YSH8 samples with sandwich structure from nano-powders yielded fracture toughness of 2.1–2.4 MPa m 0.5 , which was about 33% higher than that of conventional YSH8 sample sintered from micron powders. Both the experimental results and numerical simulation indicated that the fracture toughness is closely related to the geometry of the sandwich structure.