Flash microwave sintering of zirconia by multiple susceptors cascade strategy

In the field of flash sintering, microwave energy represents an interesting way to densify ceramics complex shapes, thanks to a contactless volumetric heating. Attaining a fast and homogeneous heating is a critical parameter and hybrid heating, using silicon carbide susceptors, is generally used. In this study, an original multiple susceptors cascade strategy is developed, using both SiC and 3D-printed ZrO2 susceptors. This novel configuration follows perfectly the flash heating scheme, even for high heating rates up to 1000 K.min-1 and leads to a high stability of the "flash" hybrid heating. Flash microwave sintering produced dense (97 % relative density) microstructures within 45 s. Based on comprehensive multiphysics simulations of the overall process, insitu dilatometry measurements, kinetics method analysis and microstructural characterizations, this work highlights the sintering behavior of zirconia and the temperature distribution during flash microwave sintering.