Corrosion Analysis for Co-Ni-O Film Adopted as the Magnetic Layer of Metal Evaporated Tape

Corrosion in Co-Ni-O film, which is adopted as the magnetic layer in metal evaporated tape media, was examined through aging tests, measurements of anode polarized characteristics, and analysis of both chemical bonding by ESCA and of crystallographic characteristics by RHEED. The following results were obtained. 1) The experimental results for exposure tests were strongly correlated with the anode characteristics. 2) Corrosion occurring in the uppermost layer of Co-Ni-O film exposed to high temperatures and high humidity progressed as follows: CoO+H2O¿Co (OH)2, 2Co (OH)2+0.5O2¿2CoOOH+H2O. 3) Both oxygen gas introduced in the deposition process, and fluorine lubricant coated onto the surface of the Co-Ni-O film give effective protection against corrosion.