Influence of Nanocrystalline MgAl2O4 Spinel Addition on the Properties of MgO-C Refractories

Nanopowders of magnesium aluminate (MgAl2O4) spinel, prepared through citrate-nitrate gel method and calcined at 800 degrees C, were incorporated to the matrix of magnesia-carbon (MgO-C) refractory. The physical and chemical properties of the nano-MgAl2O4 spinel-added (0.5 and 1.0 wt%) MgO-C bricks were compared with those of MgO-C bricks containing no spinel and commercially available micron-sized (<45 mu m) stoichiometric spinel (AR-78). It was observed that nano-spinel (NS) (1 wt%) containing MgO-C refractories effectively prevents the oxidation, slag corrosion, and penetration resistance compared to MgO-C bricks with or without micron-sized spinel added. The average pore diameter decreases, and the concentration of the fine pore increases with addition of nano-MgAl2O4 spinel in the matrix of MgO-C bricks. Due to the lower pore size and higher concentration of fine pores as well as higher amount of carbon retention, nano-MgAl2O4 spinel-added MgO-C bricks show better physical as well as chemical properties and may have potential applications in both steel and refractory industries.