The preparation and oxidation behavior of Ca-doped α-Sialon ceramic with elongated grains

In the present study, α-Sialon with elongated gains was prepared by hot-press method with CaO as sintering additive. The density, hardness, and fracture toughness measured of α-Sialon were about 3.15 g cm−3, 17.37 ± 0.48 GPa, and 5.55 ± 0.70 MPa m1/2, respectively. The oxidation behaviors of α-Sialon with elongated gains were also investigated. Results showed that the thickness of the oxidation layer after 1200 °C for 10 h and 1300 °C for 20 h in ambient air were about 15 μm and 30 μm, respectively. Bubbles were formed on the surface of the oxidation layer due to evaporation of the gas, which occurred during the oxidation process. The mass gain of all of the specimens at 1000 °C, 1100 °C, 1200 °C, and 1300 °C exhibited the classical parabolic behavior, with the parabolic rate constant (K) were about 2.05 × 10−9, 2.18 × 10−9, 3.33 × 10−8, and 4.16 × 10−8 mg2 cm−4 h−1, respectively. The value of activation energy (Ea) was about 344.46 kJ mol−1.