Phase and Microstructural Studies of Two Types Commercial Magnesia and Spinel Refractory Raw Materials with Emphasis on Impurities Characterization

Abstract

Mineralogical impurities of the used magnesia and spinel raw materials are kinds of most important factors which strongly effecton different properties of magnesia-spinel refractories such as melt/slag resistance, physical and thermo mechanical behavior. Inthis research, two types of commercially available fused/sintered magnesia and spinel raw materials were investigated in terms ofmicrostructure and phase composition with emphasis on the impurities characterization. The phase analysis was studied via X-raydiffraction and the microstructure was investigated using scanning electron microscopy and electron back scattered diffractiontechniques. X-ray patterns showed that the main phase in both spinels is MA spinel and any other impurity phases are not detected.The EBSD results revealed that the major phase of sintered magnesia is periclase and the grain boundaries were characterized asmerwinite and monticellite. In contrast, for fused one, it is found that the phase composition of grains and boundaries are very similarand were characterized as periclase, merwenite and dispersed monticellite