Kinetics Evaluation of Passive Oxidation at High Temperature of Silicon Nitride Used in the Fabrication of Lightweight Metal Matrix Composites

In the present work, the passive oxidation kinetics of silicon nitride α-Si 3 N 4 and (α+β)-Si 3 N 4 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 ( k p ) values and oxide layer depth were calculated. The oxidation kinetic constants k p , were 9.11e -16 and 6.35e -16 kg 2 /m 4 s and the oxidation depth were 4.25 nm and 3.69 nm, for α-Si 3 N 4 and (α+β)-Si 3 N 4 , 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/Si 3 N 4 magnesium matrix composite materials was successfully achieved by spontaneous infiltration process at a temperature of 800 °C. Highlights • Changes in passive oxidation kinetics of silicon nitride were identify by the β-Si 3 N 4 presence in the Si 3 N 4 powders. • The SiO 2 amorphous coating produced by passive oxidation on the silicon nitride surface reduce the contact angle between Si 3 N 4 and AZ91E magnesium alloy. • Passive oxidation of silicon nitride improves the wettability between Si 3 N 4 and AZ91E magnesium alloy.