A novel route to enhance high-temperature mechanical property and thermal shock resistance of low-carbon MgO-C bricks by introducing ZrSiO4

Conventional MgO-C bricks (graphite content > 14 wt.%) produce a great deal of greenhouse gas emission, while low-carbon MgO-C bricks have serious thermal shock resistance during high-temperature service. To enhance the high-temperature mechanical property and thermal shock resistance of low-carbon MgO-C bricks, a novel route of introducing ZrSiO4 powder into low-carbon MgO-C bricks was reported in such refractories with 2 wt.% flaky graphite. The results indicate that the low-carbon MgO-C brick with 0.5 wt.% ZrSiO4 addition has the maximum hot modulus of rupture at 1400 & DEG;C and the corresponding specimen fired in the carbon embedded atmosphere has the maximum residual strength ratio (98.6%) after three thermal shock cycles. It is found that some needle-like AlON and plate-like Al2O3-ZrO2 composites were in situ formed in the matrices after the low-carbon MgO-C bricks were coked at 1400 & DEG;C, which can enhance the high-temperature mechanical property and thermal shock resistance due to the effect of fiber toughening and particle toughening. Moreover, CO2 emission of the newly developed low-carbon MgO-C bricks is reduced by 58.3% per ton steel after using them as the working lining of a 90 t vacuum oxygen decarburization ladle.