Reactive Ultra-fast High-temperature Sintering (UHS) of alumina from boehmite

This work explores the consolidation of alumina via an innovative procedure: the reactive Ultra-fast High-temperature Sintering (r-UHS) from boehmite precursors. The method exploits Joule heating to achieve rapid densification without applied pressure and using extremely low-cost equipment. Crystallographic analysis reveals the phase evolution from γ -AlOOH to γ -Al 2 O 3 at 730 ° C, and to fully crystallized α -Al 2 O 3 above 1300 ° C after 30 s. Densification up to 93% relative density was achieved in just 60 s at 1800 ° C, with longer dwell times showing negligible improvement. The formation of a fully sintered surface shell hinders densification, suggesting that higher densities may be achievable with optimized heating schedules. The resulting samples show competitive hardness and structural homogeneity. Unlike flash sintering, r-UHS does not require stringent electrical contact, offering a scalable and robust route for fast advanced ceramic fabrication. Its simplicity, speed, low energy demand, and minimal equipment cost highlight its viability for alumina manufacturing.