The effect of carbon structure on in-situ protection for granular thin film media

The in-situ nano scale protection concept has been proposed recently based on granular thin film media. In this study, two series of samples with structure of glass substrate/NiAl/Cr/(CoCrPt/C)12/C prepared by facing target sputtering (FTS) and normal DC sputtering (DCS) were examined. FTS samples were shown to possess superior corrosion resistance than the DCS samples by accelerated environmental test and electrochemical technique developed from linear polarization resistance (LPR) measurement. Carbon structure was characterized by Raman spectroscopy. The corroded samples were observed by optical microscopy and the depth distribution of corrosion products was characterized by TOF-SIMS. We conclude that the carbon structure plays the most important role in in-situ nano scale protection for granular thin film media. We also discussed the effect of different structure carbon in inter-layer and top-layer on corrosion resistance of this kind of media.