ELECTROCHEMICAL TECHNIQUES TO AID IN THE DEVELOPMENT OF IMPROVED CARBON OVERCOATS ON MAGNETIC STORAGE MEDIA

Abstract

With the trend of decreasing the thickness of the carbon overcoat on high-density magnetic recordings, the corrosion properties of a hard disk multilayer structure are becoming a hot issue. An ideal overcoat would be uniform across the disk's surface, have low porosity and electrical conductivity as well as being impermeable to water. However, in reality this is not viable and corrosion is inevitable. One possible method of improving the corrosion resistance of carbon overcoats is to introduce carbide bilayers. In this paper the corrosion protective properties of CrC/C and BC/C nanolaminated overcoat structures have been analyzed by an electrochemical technique based on LPR measurements. The results allowed an overcoat's resistance to be correlated to its porosity and a statistical method was developed to allow easy comparison of results. The results from the electrochemical measurements were correlated with a range of surface analysis techniques.