Improvement in durability of CoCr film with carbon protective layer

Durability of CoCr film on a conventional 3.5 inch FDD was studied. The durability is improved by a graphite-like amorphous carbon protective layer (0.02 μm) prepared by DC magnetron sputtering. Ar plasma treatment prior to the carbon layer sputtering further improves the durability, up to 10⁷passes. The improved durability of the Ar plasma treatment is mainly due to the enhanced adhesion between CoCr / carbon interface by eliminating the oxidized layer on the CoCr surface. Corrosion resistance was also tested under two environments (1) at 25°C 75 %RH containing 1ppm SO2for 3 days (2) at 60°C 90%RH for 3 days after NaCl mist spray. The carbon layer exihibits greater resistance even for low Cr content.