CORROSION OF PARTICULATE AND THIN-FILM MEDIA

Magnetic recording media employ particulate dispersions of iron oxide with and without Cobalt modifications, chrome dioxide, metal particles (usually of iron), and Ba-ferrite, and thin films consisting typically of Cobalt alloys. In this paper, we studied the stability of the magnetic parameters of several commercially available media 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, H2S, and NO2. We found large corrosion effects 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. © 1990 IEEE