Abstract
Perpendicular recording media samples were exposed at 65 ℃ and 90 % RH for 6 days to trigger corrosion growth. Several corrosion spots were selected by optical surface analyzer, and then analyzed by scanning electron microscope, transmission electron microscope, and element energy dispersive X-ray spectrometry. By scanning electron microscope images, the spots were classified to the following corrosion patterns: "Rod type" and "Whisker type". Transmission electron microscope with element energy dispersive X-ray spectrometry analysis revealed that the "Rod type" was made of nickel oxides with micrometers in size, while the "Whisker type" was made of metallic cobalt with sub-micrometers in size. The nickel and cobalt were eluted from nickel-alloy layers and cobalt-alloy layers to media overcoat surface, respectively. In cross-sectional transmission electron microscope images of the samples with "Rod type", considerable deformation of media layer structures was observed, which was due to the lack of the nickel-alloy layers. Such corrosion induced the fatal error because of huge corroded materials and recording layer distortions.
