Effect of aluminum addition on microstrucrural and development of mechanical properties of andalusite - carbon - SiC refractories

Application of based andalusite refractories in industries is related to special properties of andalusite such as thermal stability of andalusite crystals and no changes on density after firing. In this research effect of different amount of Aluminum powder with optimized percent of Graphite and SiC were added to andalusite and physical and mechanical properties were investigated by density, porosity and CCS curves and microstructure, phase analysis and formation temperature of Al4C3 were investigated by (SEM), (XRD) and (DSC) respectively.The results showed that in coke atmosphere Al4C3 formed from 635°С and in presence of andalusite, Al4C3 reacted with andalusite, and SiC were formed from 1450°С and higher temperature. Also with mullitization of andalusite from 1400°С and formation of amorphous phase SiO2, in presence of carbon and Al, SiC and Al2O3 were formed. increase in the amount of Al and formation of Al4C3 and SiC at 1450°С, led to improvement of physical and mechanical properties of the samples.