In-situ formation of MgO whiskers and CNTs and their influence on the mechanical properties of low-carbon MgO–C refractory composites

Abstract

Abstract The influence of the addition of Ni(NO3)2 · 6H2O on the microstructure and mechanical properties of low-carbon MgO–C refractory composites was investigated. The results indicated that MgO whiskers and carbon nanotubes could be generated in low-carbon MgO–C refractory composites with Ni(NO3)2 · 6H2O in a reducing atmosphere at 1 200 °C. The magnitudes of the cold crushing strength, the cold modulus of rupture, the fracture displacement, and the residual cold crushing strength are increased by 47 %, 66 %, 8 % and 26 %, respectively. The MgO–C refractory composites with the addition of 0.6 wt.% Ni(NO3)2 · 6H2O result in better overall properties. The MgO whiskers were generated via a dissolution–diffusion–precipitation mechanism, and their growth is in accordance with the vapour–liquid–solid model.