Optimization design of Ta2O5-doped calcium hexaaluminate with improved sintering densification and properties for metallurgical application

Abstract

In view of the application limitation caused by poor densification and mechanical properties of calcium hexaaluminate, achieving the optimization design of the calcium hexaaluminate materials with improved sintering densification and comprehensive properties is highly required. Therefore, the present work looked at the effect of the Ta2O5 on the sintering densification, microstructure evolution, thermal shock resistance and slag resistance of the CA6 materials. Studies showed that the Ta2O5 was incorporated into the CA6 grains during the sintering process at high temperatures by substituting Al3+, greatly promoting the CA6 grain to grow along the direction perpendicular to the basal plane (c-axes), which was responsible for a more equiaxed morphology and highly dense microstructure. The in-situ formation of the Ca(TaO3)2 was able to infiltrate the pores inside the sample and resulted in the reduction of the apparent porosity. The improvement in sintering densification and decrease of porosity greatly enhanced the cold compressive strength, thermal shock resistance and slag resistance of the CA6 materials. Consequently, it can be considered that the introduction of Ta2O5 is expected to produce dense CA6 materials with improved mechanical properties, thermal shock resistance and slag resistance for the better application in metallurgical field.