Performance improvement of MgO-CaO refractories by the addition of nano-sized Al2O3

Magnesia-dolomite refractories have advantages such as stability in the basic environments, clean steel production, high corrosion resistance, proper covering in the cement furnace, and low production costs. However, their application is restricted due to low hydration resistance. In this research, the effects of nano and micro alumina particles on the microstructure, sintering behavior, and properties of magnesia-dolomite refractories were studied. For this purpose, MgO-CaO refractories were formulated using dolomite and magnetite and 0, 2, 4, 6 and 8 wt percentage nano and micro alumina were added to the formulation. Phase and microstructure analysis of the samples were performed using X-ray diffraction (XRD) and scanning electron microscopy (SEM/EDX), respectively. The results showed that by the addition of both additives (nano and micron size alumina), physical and mechanical properties such as bulk density cold crushing strength, and thermal shock resistance were improved and the hydration tendency of the magnesia-dolomite samples was decreased. However, in the samples containing nano-particles, the degree of improvement in the properties was more significant, finally, based on the obtained results and its relationship with the microstructure, the 4 and 8 wt% alumina micro and nano particles was determined as the optimum content, respectively.