Influence of graphite content on fracture behavior of MgO–C refractories based on wedge splitting test with digital image correlation method and acoustic emission

Abstract

Mechanical and thermal stresses are one of the main reasons causing the damage of MgO–C refractories in service. An in-depth understanding of the fracture behavior of MgO–C refractories is essential for the further development of high-performance MgO–C refractories. In this paper, effect of graphite content on fracture behavior of MgO–C refractories under wedge splitting test was investigated with the Digital Image Correlation (DIC) and Acoustic Emission (AE) technology. The results showed that the increase of graphite content in MgO–C refractories led to a reduction in brittleness and an improvement of thermal shock resistance. MgO–C refractories with higher graphite content were likely to generate crack at earlier loading stage and to have larger ultimate crack mouth opening displacement. It indicated a lower crack initiation resistance of MgO–C refractories and a better further damage propagation resistance. In addition, the proportion of crack in the MgO grains decreased and the tortuousness of crack path increased with the increasement of graphite content. It promoted the transformation of AE activity and energy dissipation from “burst type” to “slow release type” and the nonlinearity of MgO–C refractories mechanics behavior during failure process.