Study on the stability of Ce α-Sialon derived from SHS-ed powder

The synthesis of Ce α-Sialon powder by self-propagating high-temperature synthesis (SHS) and the sintering behaviors of Ce α-Sialon material by hot-pressing derived from SHS-ed powder with the addition of CeO2 or Y2O3 were performed in the present work. The results have shown that the phase assemblages of synthesized Ce α-Sialon powder consisted of β-Sialon, as the major crystalline phase, and small amount of α-Sialon, Ce2Si6O3N8 and AlN-polytypoid. Ce α-Sialon phase was meta-stable and would decompose to β-Sialon and JEM phase [Ce(Si6−zAlz)(N10−zOz, z≈1)] with the disappearance of Ce2Si6O3N8 and AlN-polytypoid after hot-pressing. The addition of CeO2 further encouraged the transformation of Ce α-Sialon phase, but the addition of Y2O3 did stabilize the Ce α-Sialon structure and (Ce,Y) α-Sialon phase would be as the major crystalline phase in the sintered material when 0.375 molar Y2O3 was added, in which most α-Sialon grains having elongated morphology were observed. As a result, the hardness (Hv) and fracture toughness (KIC) of sintered (Ce,Y) α-Sialon material being 15.23 GPa and 4.90 MPa m1/2 respectively were obtained.