Oxidation Kinetics of Powdered Silicon Nitride

The oxidation kinetics of powdered silicon nitride were studied in dry oxygen and dry air at 1 atm pressure between 1065° and 1340°C. An automatic recording electrobalance was used to measure the weight gain as a function of time. Parabolic oxidation kinetics were observed with an activation energy of 61 kcal/mol in dry oxygen and 68 kcal/mol in dry air. The oxidation rate in dry oxygen was approximately twice that in air. The solid oxidation product was tridymite above 1125°C and amorphous silica at 1067°C.