Enhanced mechanical performance of Al2O3-C refractories with nano carbon black and in-situ formed multi-walled carbon nanotubes (MWCNTs)

The mechanical performance of low-carbon Al2O3-C refractories can be further enhanced using the in-situ formation approach of MWCNTs. Evidently, the nickel nitrate catalyst in the matrix benefit the improved mechanical properties of Al2O3-C refractories after coking at elevated temperatures. The in-situ formation of MWCNTs and SiC whiskers contributes to their higher cold modulus of rupture. Moreover, dispersing catalyst into the binder solution promotes a fabric-like structure interlaced through MWCNTs and SiC whiskers in the binder system and thus a better bonding strength can be achieved. Compared to the Al2O3-C refractories with a close starting carbon content fabricated by adding as-received MWCNTs or the combined carbon sources of nano carbon black and flake graphite, superior thermal shock resistances were attained with the approaches presented in this paper. Additionally, MWCNTs are more influential to the toughening and SiC whiskers are more responsible for the strengthening behaviors.