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

Y-α-SiAlON (Y1/3Si10Al2ON15) ceramics with 5 wt.%BaAl2Si2O8 (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-Si3N4 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 m1/2. The complete crystallization of BAS is beneficial to the high temperature mechanical properties. The obtained could maintain the room strength up to 1300 °C.