Flash sintering is a novel field‐assisted sintering technology for ceramics that allows a dramatic reduction in processing time and temperature. Since 2010, when flash sintering was first reported, it has been a focus of research interest in the field of materials science. Recent study results have confirmed that the sintering temperature decreases with the strength of the applied electric field; for some ceramics, the sintering temperature can be lowered even to room temperature. This represents an innovative breakthrough for ceramic sintering at ultra‐low temperatures. However, once the electric field strength in flash sintering is increased, new questions and challenges arise, such as whether or not partial discharge occurs in the green body if under electro‐thermal coupling stress, how to quantitatively analyse the impact of discharge on sintering, and, moreover, whether the sintering mechanism under a strong electric field is consistent with that under a weak electric field. These research questions require knowledge of partial discharge detection, dielectric theory, and other topics that are beyond the scope of materials science. To address this need, this review summarises the work carried out in flash sintering with a strong electric field from the perspective of high voltage and insulation technology. First, the flash sintering process and mechanism are briefly introduced. Then, the published literature on flash sintering with a strong electric field for various ceramic materials is summarised in depth. In addition, experimental phenomena that are observed in flash sintering with a strong electric field, such as flash and blackening, are discussed. Finally, some suggestions for future work are presented. It is anticipated that the knowledge gap between different areas of study can be filled by this review.

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.