Effect of Ferrosilicon, Silicon and Aluminum Antioxidants on

ABSTRACT Effect of addition of various antioxidants such as ferrosilicon, pure silicon, aluminum and their combinations on microstructure and mechanical properties of magnesia-graphite refractories were investigated at different temperatures. Sample preparation and measurements were according to DIN or ASTM standards. The data showed that up to about 1300°C, the slope of the apparent porosity against temperature of the samples was positive; but lower than that of the samples containing no antioxidant. Effect of the carbothermal reduction of MgO became significant only at temperatures greater than 1400°C. At 750 to 1000°C, the CCS and MOR of the specimens without any antioxidant decreased with temperature. The depth of the decarburization layers and the percentage of the oxidation surface increased with temperature, no matter the sample contained or did not contain ferrosilicon or silicon aluminum combination. Oxidation resistance of the samples containing ferrosilicon-silicon was greater than that of the ferrosilicon or silicon containing specimens. Results indicated that the worst hydration condition was with the samples containing aluminum. Other samples showed a good resistance against hydration. Best results were obtained with the samples containing (a) 1-3 wt% silicon, (b) 2-4 wt% ferrosilicon and (c) 4% ferrosilicon plus 1% Al