This is the first study to conduct the flash sintering of 3 mol% yttria-stabilized zirconia (3YSZ) ceramics at room temperature (25 °C) under a strong electric field, larger than 1 kV/cm. At the standard atmospheric pressure (101 kPa), the probability of successful sintering is approximately half of that at low atmospheric pressure, lower than 80 kPa. The success of the proposed flash sintering process was determined based on the high electric arc performance at different atmospheric pressures ranging from 20 to 100 kPa. The 3YSZ samples achieved a maximum relative density of 99.5% with a grain size of ∼200 nm. The results showed that as the atmospheric pressure decreases, the onset electric field of flash sintering decreases, corresponding to the empirical formula of the flashover voltage. Moreover, flash sintering was found to be triggered by the surface flashover of ceramic samples, and the electric arc on the sample surfaces floated upward before complete flash sintering at overly high pressures, resulting in the failure of flash sintering. This study reveals a new method for the facile preparation of flash-sintered ceramics at room temperature, which will promote the application of flash sintering in the ceramic industry.

In this study, we reported that flash sintering (FS) could be efficiently triggered at room temperature (25 °C) by manipulating the oxygen concentration within ZnO powders via a versatile defect engineering strategy, fully demonstrating a promising method for the repaid prototyping of ceramics. With a low concentration of oxygen defects, FS was only activated at a high onset electric field of ∼2.7 kV/cm, while arcs appearing on the surfaces of samples. Strikingly, the onset electric field was decreased to < 0.51 kV/cm for the activation of FS initiated, which was associated with increased oxygen concentrations coupled with increased electrical conductivity. Thereby, a general room-temperature FS strategy by introducing intrinsic structural defect is suggested for a broad range of ceramics that are prone to form high concentration of point defects.

The development of ultra‐high voltage transmission lines requires a ZnO arrester with excellent electrical response and high voltage gradient. Compared with conventional preparation methods, flash sintering allows fast production of novel high‐performance ZnO varistor ceramics with low energy consumption and controlled grain growth. Herein, ZnO varistor ceramics were prepared using the flash sintering method at an air pressure of 21 kPa for 60 s at 25°C. The results showed that the flash‐sintered samples had fine grains and reduced loss of volatile elements. Moreover, the voltage gradient, leakage current density, and non‐linear coefficient of the flash‐sintered varistor ceramics were significantly improved compared with those of conventionally sintered samples. Owing to the short preparation time and absence of a heating process, the energy consumption of the proposed flash sintering method was significantly reduced to 10% of that by conventional sintering. The proposed method is a promising approach for the preparation of ZnO arresters with excellent electrical properties and serves as an effective method that realises energy saving and emission reduction.

No abstract

No abstract