Flash spark plasma sintering of zirconia nanoparticles: Electro-thermal-mechanical-microstructural simulation and scalability solutions

Flash sintering is a very promising method with a great potential for the ultra-rapid production of objects with firing processes of mere seconds. However, the transition from few millimeters samples to larger scales is a key issue. In this study, we explore the spark plasma sintering approach allowing a stable hybrid heating in flash condition and producing near net shape sintered specimens. Two electric current configurations are employed for diameters of 15 and 30 mm to determine the effect of scale change and of electric current concentration. These experiments coupled with a Multiphysics simulation indicate that stable flash conditions can be reached for 30 mm specimens. However, even if the electrical current concentration is very effective at small sizes, it generates peripheral hot spots for large specimen dimensions. The blackening effect on zirconia flash specimens acts then as an indicator of the specimen thermal history.