Mechanical behavior and thermal shock resistance of MgO-C refractories: Influence of graphite content

The mechanical and thermo-mechanical properties of MgO-C refractories are of major importance in the industrial applications, and highly depend on the optimization of their microstructural design. In the present work, the influence of flaky graphite content on mechanical behavior and thermal shock resistance of such refractories was investigated with the aid of the wedge splitting test, fractal and microscopic fractographic analysis. The results showed that the increase of graphite content in the specimens led to an enhanced non-linear fracture behavior, a reduced nominal notch tensile strength (σNT), and a higher specific fracture energy (Gf), characteristic length (lch) and thermal shock resistance parameter (Rst). The fractal analysis of the crack propagation path of the specimens after the wedge splitting test indicated that increasing graphite content in the refractories can enhance their irregularity of the crack propagation path during fracture. Also, it was suggested from microscopic fractographic analysis that the improvement of thermal shock resistance of MgO-C refractories was positively correlated with the increase of interface crack propagation.