Influence of different parameters on calcium hexaluminate reaction sintering by Spark Plasma

Calcium hexaluminate (CaAl12O19) is the most alumina-rich intermediate compound of the CaO–Al2O3 system. The formation of this aluminate is produced by the reaction between calcium oxide and alumina. Intermediate compounds with lower alumina content (CaAl2O4, CaAl4O7,…) are formed during the synthesis of calcium hexaluminate with increasing temperature. With the aim to obtain dense and pure calcium hexaluminate by reaction sintering method using Spark Plasma Sintering (SPS) the variation of sintering parameters was studied. Final densities close to the theoretical and calcium hexaluminate formation rates over 93% were achieved by this method. Once the sintering parameters were optimized, a study of the flexural strength and the hardness of the samples were performed.