Rapid densification and reaction sequences in self-reinforced Y- α-SiAlON ceramics with barium aluminosilicate as an additive

Abstract

Y- α-SiAlON (Y 1/3Si 10Al 2ON 15) ceramics with 5 wt.%BaAl 2Si 2O 8 (BAS) as an additive were synthesized by spark plasma sintering (SPS). The kinetic of densification, phase transformation sequences and grain growth during sintering process were investigated. Full densification could be achieved by 1600 °C without holding and using a heating rate of 100 °C min −1, but the transformation from α-Si 3N 4 to α-SiAlON is not completed simultaneously with the densification process. The equilibrium phase assemblage could be reached after SPS at 1800 °C for 5 min and the resultant material possesses self-reinforced microstructure with high hardness of 19.2 GPa and fracture toughness of 6.8 MPa m 1/2. The complete crystallization of BAS is beneficial to the high temperature mechanical properties. The obtained could maintain the room strength up to 1300 °C.