Stress-strain behaviour and degradation mechanism of low-carbon MgO-C refractories at 900-1100 °C: role of TiB2-BN-AlN waste

The use of boron-containing additives often raises concerns when exposed to high temperatures. In this study, the high temperature stress-strain behavior and degradation mechanism of low-carbon MgO-C refractories containing TiB2-BN-AlN waste were investigated. Stress-strain curve, peak axial stress, Young's modulus, cohesion, and residual strength ratio after thermal shock tests were thoroughly analyzed. The findings suggest that the mechanical properties of refractories remain unimpaired within the temperature range of 900-1100 degrees C, and can even be enhanced through the synergistic effect of TiB2-BN-AlN waste and Al powder. The optimized axial stress increased from 55.0 to 62.0 MPa at 1100 degrees C, while the cohesion increased from 10.0 to 13.8 MPa, respectively. The observed enhancement can be primarily attributed to the effective healing of pores and cracks, reduction in oxidation, and improved material cohesion. However, the excessive incorporation of boron-containing waste may compromise the performance of refractories, leading to instability or degradation.