Study on the nanocarbon containing Al2O3 – C continuous casting refractories with reduced fixed carbon content

Abstract

Alumina-carbon refractories are widely used in the continuous casting process for steelmaking due to their suitable comprehensive properties. Conventionally, these refractories contain 25-30 wt% carbon, with graphite as the major source, especially to improve corrosion and thermal shock resistances. However, the presence of high carbon encompasses several problems like high energy loss, carbon pick-up in steel, oxidation, increased CO2 generation, etc. To avoid these issues, in the present work, alumina-carbon refractories are prepared and evaluated with reduced and fixed carbon content by partially replacing the graphite with nanocarbon. Free carbon addition is maintained at 4 wt% level by varying combination of nanocarbon and graphite content. The alumina carbon refractory compositions are processed through pressing, curing, coking, and evaluated for properties like bulk density and cold crushing strength. Phase analysis and microstructural variations in the compositions are studied along with oxidation resistance at different temperatures. Because of its smaller particle size, nanocarbon can easily fill the gaps between the other refractory particles thereby reduces porosity and improves strength. Also, greater extent of in situ aluminum carbide formation improves the strength in case of nanocarbon containing compositions.