Influence of forming methods on the microstructure of 3YSZ flash-sintered ceramics

We evaluated the influence of three different forming methods (uniaxial and isostatic pressings and slip casting) on the densification and microstructure of cylindrical flash sintered 3mol% yttria-stabilized zirconia (3YSZ) ceramics. Conventional sintering was also analyzed as a comparison. Irrespective of the forming method applied, all the conventionally and the flash sintered specimens presented high final densities. Regarding the grain size distribution, while conventionally sintered specimens presented homogeneity over the entire ceramics, flash sintering yielded specimens with grain size heterogeneity depending on the forming method used. The microstructure of the specimens prepared with slip casting was homogeneous. On the other hand, uniaxial pressure induced bigger grains at the core of the ceramics. This heterogeneity is attributed to the presence of green density gradients in the samples prepared by uniaxial pressing, which affects the current flow and, consequently, the heat distribution within the specimens. [Display omitted]