Corrosion of Thin Film Magnetic Disk: Galvanic Effects of the Carbon Overcoat

Thin film magnetic disks are usually coated with a layer of carbon or silica to improve wear properties, enhance flyability, and reduce environmental degradation of the underlying metal layers. In this paper we investigated the effect of dc and RF sputter deposited carbon overcoats on the corrosion behavior of the magnetic layers using electrochemical techniques and a corrosive gas chamber. Corrosion test samples were characterized by optical microscopy, ellipsometry, scanning electron microscopy (SEM), and scanning Auger spectroscopy (SAM) in order to establish the mechanism of corrosion. Corrosion of the magnetic layer was found to be galvanically coupled to the carbon overcoat and influenced by several disk processing parameters. © 1989, The Electrochemical Society, Inc. All rights reserved.