Effect of MgAl2O4 nanoparticles addition on the densification and properties of MgO-CaO refractories

MgAl2O4nanoparticles were added to MgO-CaO refractory ceramic composites in the range of 0-8 wt%. Refractory specimens were obtained by sintering at 1650 °C for 3 h in an electric furnace. Refractory specimens were characterized by measurements of bulk density, apparent porosity, hydration resistance, cold crushing strength, crystalline phase formation, and microstructural analysis. Results show that with additions of MgAl2O4 nanoparticles the bulk density of the samples increased. But the apparent porosity and cold crushing strength decreased and increased, respectively with addition MgAl2O4 nanoparticles up to 6 wt% and for further MgAl2O4 nanoparticles, due to the thermal expansion mismatch, the results is reversed. Also, the hydration resistance of the samples was appreciably improved by the addition of MgAl2O4 nanoparticles due to its effect on decreasing the amount of free CaO in the refractory composite and promotion of densification by creating a dense microstructure.