Nanoscale toughening of low carbon Al ₂ O ₃ ‐C refractories by means of SiC _nw /Al ₂ O ₃ composite reinforcement

Abstract

Abstract To improve the thermal shock resistance of low carbon Al 2 O 3 ‐C refractories, SiC nanowires (SiC nw ) containing SiC nw /Al 2 O 3 composite reinforcement were introduced. The specific fracture energy of the Al 2 O 3 ‐C refractory matrix was obtained by statistical grid nano‐indentation. The reinforcement mechanism of SiC nw /Al 2 O 3 on thermal shock resistance of refractories was investigated. The results revealed that the matrix‐specific fracture energy of A6 (6 wt% SiC nw /Al 2 O 3 added) was 217 N/m, which was 58.4% higher than reference sample A0 (137 N/m) and 18.6% higher than MA6 (183 N/m, 6 wt% SiC/Al 2 O 3 added). A6 showed the highest residual strength ratio of 49.8%, which was 114.7 % higher than A0 (23.2%) and 82.4 % higher than MA6 (27.3%). The components with different morphology in SiC nw /Al 2 O 3 cluster, especially SiC nanowires, promote the generation of microcracks, crack multi‐deflection, and branching, which toughen the matrix and improve the thermal shock resistance of refractories. In comparison to the literature, A6 showed a higher rising in residual strength ratio than those with higher graphite content (4 wt% and 20 wt%), which will greatly reduce the consumption of carbon‐containing refractories and contribute to the reduction of CO 2 emission.