Effect of nano-titania (η-TiO2) content on the mechano-physical properties of a magnesia refractory composite

The mechano-physical properties of a sintered magnesia matrix containing 0-8 wt% nano-titania (η-TiO2) have been investigated. The crystalline phases and microstructure characteristics of the refractory specimens sintered by solid state at 1500 °C for 4 h in an electric furnace were studied by X-ray diffraction (XRD), and scanning electron microscopy (SEM) with microanalysis (EDS), respectively. The physical properties are reported in terms of density and porosity. The mechanical behavior was evaluated by a cold crushing strength (CCS) test. As a result, it was found that the presence of η-TiO2 in the magnesia matrix induced titanates formation (Mg2TiO4 and CaTiO3), which improved the sintering process. Nano-titania also produced a fine-grained microstructure with intergranular second phase particles, which remain at the boundary and exert a pinning effect. In general, the addition of 5 wt% of η-TiO2 contributed to reach a maximum increment in physical and mechanical properties.