Flash sintering of Al2O3-8YSZ composites
Flash sintering is a novel field-assisted sintering technique that allows to densify ceramics in few seconds at limited temperature. The flash effect has been proven to be correlated to thermal runaway of Joule heating which inhibits the processing of highly insulating systems like high purity alumina.
The addition of a conductive fillers can facilitate the flash transition in several oxide ceramics. In the present work we studied the flash sintering behavior of Al2O3 composites containing different amount of 8YSZ (conductive phase). The mix was produced (i) by manual dry mixing, (ii) producing an initial Al2O3-8YSZ powders suspension in apolar solvent and (iii) precipitating 8YSZ on Al2O3 powder starting from Zr and Y salts in water solution. The flash onset is shown to depend on the dispersion method and to decrease with the amount of conductive phase. The densification results affected by the electric current limit.