Effect of carbon black on corrosion resistance of Al2O3–SiC–C castables to SiO2–MgO slag

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Metallurgical solid waste recycling is the shape of things to come in green development of Chinese iron and steel industry. Utilization of ironworks slag for producing mineral wool at high temperature is an important approach. However, refractory lining is seriously corroded by the SiO2–MgO based slag at 1600 °C during the production process. Different production steps need different atmospheres, the changeable service atmospheres (air and reducing atmosphere) put forward high requirements for slag resistance. The Al2O3–SiC–C castables containing carbon black are usually used in iron runner, which faces high-temperature service condition of 1450 °C–1500 °C. Nevertheless, the function of carbon black in the Al2O3–SiC–C castables at 1600 °C is till essentially unknown. In the current study, the carbon black was introduced to tabular alumina based Al2O3–SiC–C castables to improve corrosion resistance to SiO2–MgO based slag at 1600 °C. The result showed that 0.4 wt% carbon black was suitable for the castables, which the slag resistance of castables was significantly improved. The carbon black had contributed to block slag by wettability resistance. By comparison with the castables without carbon black, the corrosion index and penetration index had been reduced by 20.2% and 28.0%, respectively, under air atmosphere. And there were little corrosion or penetration under reducing atmosphere for castables with 0.4 wt% carbon black. For the mechanical properties, the Al2O3–SiC–C castables with 0.4 wt% carbon black could serve production process although the carbon black impaired the physical properties.