The Effect of Temperature, Humidity, and Silicon Content on the Oxidation of Fine Iron Particles

In this study, the oxidation and electrochemical corrosion of Fe-Si particles used in magnetic recording are investigated under controlled thermal and relative humidity conditions. The relative humidity, above a threshold value, dominates the oxidation behavior. Oxidation kinetics increase greatly above this threshold, and a portion of the exposed particle population becomes completely oxidized. X-ray diffraction data confirm the appearance of α-Fe₂O₃ in addition to the usual γ-Fe₂O₃ following exposure to high humidities. Greater silicon content increases the threshold humidity, above which rapid degradation in magnetic properties occurs.