Morphology characterization of periclase–hercynite refractories by reaction sintering

A periclase？hercynite brick was prepared via reaction sintering at 1600℃for 6 h in air using magnesia and reaction-sintered hercynite as raw materials. The microstructure development of the periclase-hercynite brick during sintering was investigated using X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy in combination with energy-dispersive X-ray spectroscopy. The results show that during sintering, Fe^2＋, Fe^3＋ and Al^3＋ ions in hercynite crystals migrate and react with periclase to form（Mg1-xFex）（Fe2-yAly）O4 spinel with a high Fe/Al ratio. Meanwhile, Mg^2＋ in periclase crystals migrates into hercynite crystals and occupies the oxygen tetrahedron vacancies. This Mg^2＋ migration leads to the formation of（Mg1-uFeu）（Fe2-vAlv）O4 spinel with a lower Fe/Al ratio and results in Al3＋ remaining in hercynite crystals. Cation diffusion between periclase and hercynite crystals promotes the sintering process and results in the formation of a microporous structure.