Densification behavior of flash sintered boron suboxide

Abstract

A study to quantify the flash sintering kinetics of boron suboxide (B6O) under various electric field strengths and cut‐off amperages is presented. B6O is conventionally sintered at a prolonged temperature above 1800°C, near its thermal decomposition temperature, with an overpressure >3 atm. By applying a direct current (DC) electric field across a green powder compact, B6O can be sintered at 1000°C at atmospheric pressure. During the flash sintering process, an intensive radiation was emitted (electroluminescence), which is distinct from the thermal radiation (thermoluminescence) that is expected in conventional sintering. It was observed that the degree of sintering of the large B6O specimen was heterogeneous due to apparent localization of electrically conducting paths. The material near the surface was sintered, but the core of the specimen was not. It was found that the flash event occurred at a critical temperature, which was obtained by combining external heating via ambient furnace conditions and internal Joule heating. The progressive densification behaviors of the B6O are also presented.

Review of flash sintering with strong electric field

“…Under certain conditions, the hot spot may cause the test sample to melt locally [67]. For example, a hot spot along with partial sintering of the test sample was observed during a flash sintering experiment with B 6 O [68]. In particular, the material near the surface was sintered into a dense shell, whereas the core of the specimen remained unsintered.…”

Flash sintering of zircon: rapid consolidation of an ultrahigh bandgap ceramic

“…This innovative sintering technique presents several advantages when compared to conventional sintering, such as the reduction of time and costs due to the lower temperatures and shorter sintering times [20,21]. Reduced sintering time and lower furnace temperature have other associated beneficial effects reflected in the fine grained/nanometric microstructure [22], and the consolidation of out-of-equilibrium phases [20,23]. The absence of constrained sintering upon FS makes this technique suitable for the preparation of multilayered and composite ceramics [24].…”

Instrumentação e automação de forno tubular adaptado à técnica >i<flash sintering>/i<: aprimoramento do processo de sinterização da zircônia

“…RASHKOVA; RAJ, 2010; M'PEKO; FRANCIS; RAJ, 2014; PEREZ-MAQUEDA et al, 2017;SPIRIDIGLIOZZI et al, 2017). Outros trabalhos reportaram benefícios da FS na sinterização de materiais metaestáveis e/ou evitando formação de fases não desejadas (SHOMRAT et al, 2015;CASTLE et al, 2016CASTLE et al, , 2017YU et al, 2018;MCWILLIAMS;PARKER, 2018). Um Mais recentemente, alguns trabalhos foram publicados aplicando a FS para sinterizar materiais estabilizados por entropia ('high entropy stabilized ceramics') (BIESUZ et al, 2020a;KUMAR et al, 2020;LIU et al, 2020aLIU et al, , 2020cWANG et al, 2020b;YOON et al, 2020).…”