Densification and thermal gradient evolution of alumina during microwave sintering at 2.45 GHz

This paper presents research on the densification and thermal gradient evolution of pure and magnesia-doped alumina during microwave sintering in a multimode cavity. Dimensional changes of pellets are registered by a contactless dilatometer that is part of a specifically prepared experimental system. Measurements of dimensional changes are compared to results obtained during sintering in the conventional dilatometer and show a palpable effect of microwaves when alumina is doped by magnesia. This system also allows monitoring of temperature distribution on the surface sample from temperatures of about 700 °C. Analysis of thermal evolution shows gradient inversion for both examined powders.