The influence of silica nanoparticles addition on the physical, mechanical, thermo-mechanical as well as microstructure of Mag-Dol refractory composites

The high hydration potential of CaO and MgO phases restricted the application of Mag-Dol refractory composites. In this study, the impact of nano-silica (SiO2) addition on the physical, mechanical, thermo-mechanical as well as microstructure of Mag-Dol refractory composites is investigated. Mag-Dol compositions were prepared by using calcined dolomite and magnesite particles (micron, 0-1, 1-3, 3-5, and 5-8 mm), liquid resin, and 0, 0.5, 1, 1.5, 2, and 2.5 wt% nano SiO2 as additives. Specimens were heated up to 1650 degrees C for the 3 h soaking period. Fired specimens were characterized by physical (apparent porosity, bulk density, and hydration resistance), mechanical (cold crushing strength), and thermo-mechanical (flexural strength at 1200 degrees C) measurements. XRD and SEM/EDS analysis were done to study phases and microstructure analysis of the fired samples, respectively. Results showed that by adding up to 2.5 wt% nano-SiO2, due to the formation of CaO center dot MgO center dot 2SiO(2) (Diopside), 2CaO center dot MgO center dot 2SiO(2) (Akermanite), and CaO center dot MgO center dot 2SiO(2) (Monticellite) phases, physical and mechanical properties were enhanced. But the highest flexural strength value is achieved for 1 wt% nano-SiO2 containing sample.