Corrosion of particulate and thin film media

The stability of the magnetic parameters of several commercially available media was studied by measuring the bulk magnetic properties before and after exposure to different accelerated corrosion tests in environments of elevated temperature and humidity, and also in environments with traces of reactive species of Cl₂, H₂ S, and NO₂. Large corrosion effects were found reflected in irreversible reduction in the saturation and remanent magnetization of the metal particle and some of the thin-film media. Considerable loss of magnetization was also observed in the CrO₂ media under high-humidity conditions. The Co-modified iron oxide media experienced a considerable reduction in their coercivity. Only the gamma-iron oxide and the Ba-ferrite particulate media and a CoCrTa thin-film alloy with a high content of Cr were essentially stable