Flash sintering of ultra‐high pure alumina ceramics with fine microstructure

Abstract The nearly fully dense ultra‐high pure (>99.99%) α‐Al 2 O 3 ceramics were prepared by flash sintering at the furnace temperature of 1300°C. Compared with the samples sintered at 1300 and 1650°C without electrical field, the flash‐sintered samples exhibited remarkably improved density and finer grains. The flash‐sintered samples also exhibited high hardness, which is even higher than that of the hot‐pressed sample. Therefore, it is believed that flash sintering could be an effective technique for the preparation of ultra‐high pure alumina ceramics.