The influence of Al2O3 nanoparticles addition on the microstructure and properties of bauxite self-flowing low-cement castables

In this research, the impact of Al2O3 nanoparticles addition on microstructure, mechanical, and physical properties of bauxite self-flowing low-cement castables were investigated. Also, the optimum amount of Al2O3 nanoparticles is determined. For this propose, up to 3 wt% Al2O3 nanoparticles were added to the bauxite castable compositions. The physical and mechanical properties of castable compositions such as bulk density (BD), apparent porosity (AP), self-flow values (SFV), and cold crushing strength (CCS) were examined. Also, the X-ray diffraction (XRD) and scanning electron microscopy (SEM/EDX) techniques were used for detection the ceramic phase's formation and microstructural analysis of the castables compositions, respectively. Results show that addition of Al2O3 nanoparticles up to 1 wt% improved the properties of bauxite self-flowing low-cement castables. As well as, the use of Al2O3 nanoparticles led to the formation of the platy and needle crystalline phases such as hibonite (CaO·6Al2O3), calcium dialuminate (CaO·2Al2O3), and mullite (3Al2O3·2SiO2), between the grain boundaries of the bauxite particles. Also, Al2O3 nanoparticles addition led to aforementioned phase formation occur at the lower temperatures.