Microstructure and Properties of ZrB2-SiC Ceramic Composites Enhanced by Yttrium Compounds

In this study, ZrB 2 -SiC-based ceramic composites were fabricated via hot pressing by incorporating Y 2 O 3 and YF 3 additives, respectively, to optimize their microstructure and comprehensive performances. The results indicate that both additives promoted sintering densification and mechanical reinforcement through the in situ formation of YBO 3 phases at the grain boundaries. Notably, the addition of YF 3 yielded superior overall performance compared to Y 2 O 3 . The composites with added YF 3 achieved relative density of 99.82%, with hardness of 14.55 GPa, flexural strength of 366.3 MPa, and fracture toughness of 5.72 MPa·m 1/2 . Crucially for electrode applications, the high densification facilitated the formation of a robust conductive network, resulting in a high electrical conductivity of 6.12 × 10 6 S/m. Regarding oxidation resistance, F − effectively reduced the viscosity of the glass phase protective layer. This enhanced flowability facilitated rapid self-healing of surface defects, resulting in significantly superior oxidation resistance compared to the Y 2 O 3 added composites. This work demonstrates that YF 3 is a highly effective sintering additive for tailoring ZrB 2 -SiC-based ceramic composites to fabricate high-performance ceramic electrodes.