Fabrication of zirconium nitride‐zirconia toughened alumina core‐shell ceramics as surrogate for the uranium nitride‐uranium dioxide core‐shell ceramic fuel

Abstract The zirconium nitride‐zirconia toughened alumina (ZrN‐ZTA) core‐shell ceramics, whose shell was the ZTA and core was the ZrN‐ZTA with ZrN content between 0 and 88 vol.% were successfully fabricated by powder metallurgy method combined with spark plasma sintering in order to improve the oxidation and corrosion resistance of ZrN ceramics used as a surrogate fuel of uranium nitride. Experimental results showed that the core‐shell ceramics fabricated were intact and crack‐free, and the interfaces between the shell and the core were well‐defined and coherent without apparent defects. Also, all of the ZTA ceramic shells exhibited similar dense microstructure and mechanical properties. When ZrN content in the core increased from 0 to 88 vol.%, the Vickers hardness of the core was increased and then decreased, and fracture toughness was also increased to 5.42 ± 0.31 MPa·m 1/2 and then decreased to 4.32 ± 0.25 MPa·m 1/2 . The core‐shell ceramics fabricated in this study with the high nitride content have demonstrated reliable microstructure and mechanical properties, which can be potential candidates for application as accident‐tolerant fuel in nuclear energy systems.