The effect of nano-Cr2O3 on solid-solution assisted sintering of MgO refractories

The effect of Cr2O3 particle size on the densification of magnesia refractories was investigated. Magnesia grains (<45 μm) were mixed with 2 wt% of micro-Cr2O3 (2 μm) and nano-Cr2O3 particles (10–20 nm) and sintered at 850–1450 °C, for 5 h in air. The progress of the densification and phase evolution of samples was studied with the support of X-ray diffraction phase analysis (XRD), Fourier transformer infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). It was shown that the densification of magnesia was enhanced by reducing the particle size of the added chromia to the range of 20 nm. According to the phase analysis results, the higher dissolution rate of Cr2O3 in MgO in the MgO–Cr2O3 system was responsible for the faster densification of nano-Cr2O3 containing mixes.