Comparison of Corrosion and Tribological Properties of Ultrathin (<2 nm) Carbon Films on Hard-Disk Media by DC Sputtering and FCVA Processes

Ultrathin carbon overcoats (COCs) are of great interest for future hard-disk media. In view of future requirements, the key research focus lies in investigating/maintaining tribological and oxidation resistance properties of different types of COCs with thicknesses <;2nm. We report on the tribological and oxidation resistance properties of sputtering and filtered cathodic vacuum arc (FCVA) processed ultrathin COCs of thicknesses in the range of ~1.2-1.6nm. FCVA-deposited 1.6nm COC exhibits excellent properties in terms of lower coefficient of friction (COF, 0.2-0.25), higher wear resistance and greater oxidation resistance. In contrast, sputtered 1.2 and 1.5nm COCs show higher COF (~0.4-0.5), poor wear and oxidation resistance properties. The tribological and oxidation resistance performance of 1.2 and 1.6nm thick FCVA-processed COCs are found to be comparable with, or even better than, significantly thicker ~2.7nm commercial COC, demonstrating the effectiveness of the FCVA processed ultrathin protective magnetic media overcoats.