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

In the present study,alpha-Sialon with elongated gains was prepared by hot-press method with CaO as sintering additive. The density, hardness, and fracture toughness measured of a-Sialon were about 3.15 g cm(-3), 17.37 +/- 0.48 GPa, and 5.55 +/- 0.70 MPa m(1/2), respectively. The oxidation behaviors of alpha-Sialon with elongated gains were also investigated. Results showed that the thickness of the oxidation layer after 1200 degrees C for 10 h and 1300 degrees C for 20 h in ambient air were about 15 mm and 30 mm, 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 degrees C, 1100 degrees C, 1200 degrees C, and 1300 degrees C exhibited the classical parabolic behavior, with the parabolic rate constant (K) were about 2.05 x 10(-9), 2.18 x 10(-9), 3.33 x 10(-8), and 4.16 x 10 (-8) mg(2) cm(-4) h(-1), respectively. The value of activation energy (Ea) was about 344.46 kJ mol(-1). (C) 2017 Elsevier B.V. All rights reserved.