Kinetics evaluation of passive oxidation at high temperature of silicon nitride used in the fabrication of lightweight metal matrix composites

Abstract

Abstract In the present work, the passive oxidation kinetics of silicon nitride α-Si3N4 and (α+β)-Si3N4 powders at different temperatures from 1000 to 1200 °C were evaluated. Oxidation of these powders was carried out to improve wettability and pressureless infiltration of AZ91E Mg-alloy. The oxidation kinetic constant (kp) values and oxide layer depth were calculated. The oxidation kinetic constants kp, were 9.11e-16 and 6.35e-16 kg2/m4s and the oxidation depth were 4.25 nm and 3.69 nm, for α-Si3N4 and (α+β)-Si3N4, respectively. Furthermore, passive surface oxidation of silicon nitride was performed in order to achieve affinity between silicon nitride and AZ91E magnesium alloy. Therefore, the manufacture of AZ91E/Si3N4 magnesium matrix composite materials was successfully achieved by spontaneous infiltration process at a temperature of 800 °C.