Studies on the Effect of Alumina Aggregates on he Performances of Alumna-Carbon Refractories

Alumina-carbon (Al2O3-C) refractories are extensively used for steel making application particularly for continuous casting of steel owing to its high modulus of rupture and high cold crushing strength, low thermal expansion coefficient, high thermal conductivity, high thermal shock resistance and resistance to molten slag and metal. The effect of alumina aggregates on the physical, mechanical, thermal and thermo-chemical properties of Al2O3-C has been systematically studied in this present investigation. White fused alumina (WFA), brown fused alumina (BFA) and tabular alumina (TA) have been used as a source of alumina. Flakey graphite has been used as a source of carbon. Fused silica has been incorporated into the Al2O3-C composition in order to provide low thermal expansion coefficient of the Al2O3-C refractories. Phenolic resins were used as binder to bind the different aggregates of the Al2O3-C refractory formulation. Different Al2O3-C refractory formulation were prepared by varying the alumina aggregates (types) and amount keeping total alumina aggregate, fused silica aggregate, graphite and binder unaltered. Physical properties like apparent porosity (AP) and bulk density (BD), mechanical properties like cold modulus of rupture (CMOR), cold crushing strength (CCS), and modulus of elasticity (MOE), thermal expansion coefficient (TEC) and thermo-chemical properties like oxidation resistance and erosion resistance were studied as a function of alumina aggregate (amount and type) of the fired (10500C for 3 hr) Al2O3-C refractory samples. Although the alumina aggregate substitution showed a negligible variation in the physical properties of the Al2O3-C refractory it shows a substantial effect on the mechanical and thermo-chemical properties. The observed results has been correlated the aggregates type, morphology, (size, shape and distribution). An attempt has also been made to study the effect of metallic silicon antioxidant addition on the above properties were studied as a function of alumina aggregate type