Enhanced oxidation resistance and thermal shock resistance of low-carbon Al2O3–C refractories with nano-BN: A synergistic of mullitization behavior

Abstract

The thermal shock stability and oxidation resistance of Al2O3–C refractories are of critical importance for iron and steel making processes. In rapid and repeated thermal shock environments, materials require excellent thermal shock stability and oxidation resistance. In this study, nano-BN synthesized was used to introduce Al2O3–C refractories, as well as in evaluating the oxidation resistance and thermal shock resistance of the materials. The results shows that B2O3 was formed rapidly in the refractory containing nano-BN under low temperature oxidation, hence, it led to the decrease of the formation temperature of the dense insulating layer. As a result, the low temperature oxidation resistance of the material was improved. Simultaneously, at high temperatures, Al18B4O33 enhanced the formation kinetics of Al6Si2O13 by providing epitaxial nucleation sites, forming a synergistic structure of Al18B4O33 and Al6Si2O13. This change promoted the connection of the oxide layer, thereby greatly improving the oxidation resistance of the material. Moreover, the introduction of nano-BN was beneficial for improving the thermal shock stability of Al2O3–C refractories.