Can Ultra-fast High Temperature Sintering (UHS) Boost Transparency of Alumina?

Abstract Established routes for consolidation of transparent alumina ceramics by pressure-less sintering requires several hours of dwelling in a reducing atmosphere at a temperature exceeding 1600 ℃. Here, for the first time, we report on low temperature and ultrafast consolidation of translucent alumina ceramics. Transparency was promoted by the synergistic of high initial green density (62.7 %) and rapid sintering using Ultra-fast High Temperature Sintering (UHS) technique. The proposed approach, using a heating rate of 430 ℃/min and dwelling time of 15 minutes, resulted in ultra-fine-grained translucent alumina ceramics at 1359 ± 57 ℃ with a grain size of 0.39 µm, and an in-line transmittance of 28.7 % at a wavelength of 700 nm. For comparison, conventionally fired counterparts were opaque due to their incomplete densification, pore coalescence.