Oxidation resistance and mechanical properties of low-carbon MgO-C refractories enhanced by Al/TiB2 addition

In the low-carbon MgO-C refractories using for ladle linings, the bonding strength of the interface between the decarbonized zone and the unoxidized one, oxidation resistance, and mechanical properties were essential to improving the quality of ultra-low-carbon steel products. The present work investigated the influence of Al/TiB2 addition to low-carbon MgO-C refractories by comparing to traditional Al addition. The results showed that the bonding strength of the interface was improved by TiB2 oxidation to generate liquid Mg3B2O6 to promote the densification of porous zone within the interface. Furthermore, the CaTiO3 and Mg2SiO4 ceramic phases generated by high-temperature liquid phase reaction enhance the bonding strength the matrix and MgO aggregates. Meanwhile, the formation of tetrahedral Mg(Al,Ti)O4 and conical TiCxN1-x solid solutions by the periodic-bond-chain theory and the V-L-S growth mechanism, respectively, improved the structural strength of refractories. Compared with using a single Al addition, the refractories with the 2 wt% Al/1 wt% TiB2 addition had excellent bonding strength of the interface, oxidation resistance increased by 67.1 % and CCS (83.3 MPa) after oxidation treatment increased by 14.3 %.