Corrosion of combustion-synthesized β-SiAlONs in supercritical water

The corrosion of beta-Si(6-z)Al(z)O(z)N(8-z)s (z = 1, 2, and 3) prepared by combustion synthesis (CS) followed by spark plasma sintering (SPS) was investigated in supercritical water at 400 degrees C/30 MPa for 100 h. The corrosion behavior was studied by means of gravimetry, X-ray diffraction (XRD), scanning electron microscopy (SEM)/energy dispersive X-ray spectrometer (EDS). The mass loss and corroded layer decreased with the increasing in z value, and the results of XRD showed the oxide formed on beta-SiAlONs (z = 1, 2, and 3) is aluminum silicate (Al2SiO5). Finally, we proposed the reaction mechanism of these materials in supercritical water. (C) 2011 Elsevier Ltd. All rights reserved.