Oxidation of Thin Sheet Reaction‐Sintered Silicon Nitride

Abstract

Oxidation of reaction‐sintered silicon nitride was studied in damp air. The formation of “passive” silica films was investigated at 1 atm and 700 to 1100°C and some limited work on weight loss behavior was performed in vacuo of 10 −8 to 10 −5 atm at 1050 to 1200°C. Passive behavior was dominated by reaction in the pore network. Oxidation was extensive at 900 to 1000° but slight at 700 to 800°C. At 1100°C a protective skin limited reaction. Weight loss in vacuo was slight at 1050°C. The vacuum pressure required to suppress the weight loss increased from 4 to 5 × 10 −7 atm at 1050° to 1.5 to 2.5 × 10 −5 atm at 1200°C.