Fabrication and oxidation behavior of β-SiAlON powders in presence of trace Y2O3

Abstract

β-SiAlON powders were fabricated using Al, Si, α-Al2O3 and trace Y2O3 powders as starting materials in flowing nitrogen atmosphere. The effect of Y2O3 on oxidation behavior of the prepared β-SiAlON powders has been investigated. The results show that the Y2O3 contributed to the generation of β-SiAlON during the fabricated process. The weight gain ratio of β-SiAlON in presence of Y2O3 is higher than that of without Y2O3 during non-isothermal oxidation up to 1723 K, which may be due to the Y2O3 dissolving into the lattice of β-SiAlON resulting in lattice deformation. At the initial oxidation period, the incorporation of Y2O3 increases the oxidation rate and decreases the oxidation activation energy (Ea) of β-SiAlON due to the lattice deformation increasing the reactivity of β-SiAlON. However, at the final oxidation period, denser glass film formed on the surface of β-SiAlON because of the incorporation of Y2O3, which reduces the opportunity for O2 contact with β-SiAlON, thus decreasing the oxidation rate and increasing the Ea of β-SiAlON.