Microwave-aligned sintering of ferrites

Sintering of ceramics using microwaves can lead to improved material quality and productivity. The technical implementation of the microwave technology is still lacking because of different temperature distribution inside the specimen due to volumetric heating compared to conventional sintering. The development of microwave-aligned processes require the determination of the inside temperature distribution by means of mathematic concepts. Therefore a simplified model was set up which consists of a thermodynamic and a heat source model. Heat transfer within the specimen and the periphery will be included. To govern the heat process this model was integrated into a control algorithm. The control concept was proven by experiments using nickel-zinc-ferrite. The system provides effective protection against thermal-runway and incorrect temperature differences in the specimen. Simultaneously changes of temperature depending electromagnetic and thermodynamic material properties can be counter steered.