Diamond-like film as a corrosion protective layer on the hard disk

A magnetic layer based on Go-alloys does not possess the necessary mechanical durability and corrosion resistance and must be covered with a protective layer. An accelerated electrochemical test has been conducted on a hard disk magnetic layer covered with amorphous hydrogenated carbon doped with nitrogen. From the potentiodynamic and DC polarization measurements of the corrosion current in a 0.15 M NaCl solution adjusted to different pH, it was concluded that an acid environment can largely decrease the reliability and lifetime of a hard disk. Lubricant can contribute to corrosion protection by covering voids and other overcoat imperfections and prevent water vapor penetration into the magnetic film. Atomic force microscope images show localized distribution of corrosion sites with a density of 1.2 x 10(6) defects/cm(2). The overcoat also prevents a lateral spread of the corrosion products across a disk. (C) 2000 Elsevier Science S.A. All rights reserved.