| Abstract Scope |
Flash sintering of 8 mol% yttria-stabilized zirconia (8YSZ) involves coupled Joule heating, evolving electrical conductivity, and defect-chemistry effects. However, the influence of oxygen activity during processing is still not fully understood. This study compares flash-sintering behavior in air with high-vacuum experiments conducted at approximately 10⁻⁴ Pa. In air, current-voltage measurements, densification results, and postmortem SEM observations show sustained flash behavior under current-limited conditions. High-vacuum tests, by contrast, exhibit a brief flash-like increase in current, pronounced electrochemical reduction, and limited consolidation even after extended electric-field exposure. These differences suggest that the surrounding oxygen environment actively affects specimen conductivity, electrode overpotential, Joule-heating distribution, and anode/cathode microstructural asymmetry. By relating electrical response, density evolution, and microstructural changes across the two atmospheres, this work highlights oxygen activity as an important processing variable governing flash sustainment and microstructure development in 8YSZ under applied electric-field processing conditions. |