Influence of Oxide Nanoparticles of Fe, Al and Si on the Sintered Magnesia for the Production of Refractory Material to Be Used in Secondary Ladle Metallurgy

摘要

Iron oxide (Fe_2O_3, 20-40 ran), aluminum oxide (Al_2O_3, 50 nm) and silicon oxide (SiO_2, 20-60 run) nanoparticles were mixed in different concentrations (1 to 5 wt %) in a magnesium oxide matrix to develop new refractory matrixes as candidates in the lining of secondary ladle metallurgy. To avoid agglomeration of nanoparticles in the magnesium oxide (MgO) matrix, it was carried out a dispersion method of nanoparticles with different dispersants. After that, the powder mixture was sintered at a temperature of 1300 and 1500 ℃ for 4 hours. The refractory samples obtained were studied using X-ray diffraction (XRD) and scanning electron microscopy with energy dispersive X-ray spectrometer (SEM-with EDX) and also measured their density and porosity. The results showed that the samples sintered at 1500 ℃ with 5 wt % of Fe_2O_3 reached the highest density and presented the MgFe_2O_4 spinel-type phase. With the addition of Al_2O_3-nanoparticles in the MgO matrix, there were the formation of MgAl_2O_4 spinel phase and in the case of SiO_2-nanoparticles addition it was observed the formation of Mg_2SiO_4 forsterite phase. It is well known that with the increase in spinel phase in the matrix, there is a significant help to retain quantities of ions of iron and nickel due to the dissolution of the slag into the refractory material extending their lining life.