Improved thermal shock performance of Al2O3–C refractories due to nanoscaled additives

Carbon bonded alumina refractories with approximately 30 wt.-% residual carbon after coking are widely used as functional components such as submerged entry nozzles, monobloc stoppers and ladle shrouds in steel casting operations. Compositions with less residual carbon after coking based on nanoscaled magnesium aluminate spinel (MgAl2O4), alumina nanosheets (α-Al2O3) and carbon nanotubes (CNTs) either as single additives or combinations have been investigated according to their physical, mechanical and thermo-mechanical properties. The combination of nanoscaled powders based on carbon nanotubes and alumina nanosheets lead to superior thermal shock performance with approximately 30% less residual carbon in comparison to commercial available material compositions.