Preparation of Magnetite-Silica Composite by Non-Firing Solidification Method and Its Microwave Heating Properties

The magnetite-silica (Fe3O4-SiO2) composites with high magnetite contents for microwave heating elements were fabricated by the non-firing solidification method. Although the obtained solidified composite had a relative density of 47–57% and was not a dense body, it had sufficient mechanical strength due to the solidification of the silica phase. The magnetite in the composite functions as the microwave heating phase, and the SiO2 phase and pore phase function as the microwave permeable phase, resulting in a structure that allows uniform heating to reach the inside of the composite structure. It was clarified that the solidified composite could generate heat up to about 500°C without oxidizing during the microwave heating process.