Anti-corrosion thin protective film for vacuum deposited Co-Ni-O layers

This paper develops ca. 10nm thick anti-corrosion plasma polymerization coating for vacuum deposited Co-Ni-O magnetic recording layer. Corrosion resistance of the coated magnetic tape varied with the change of monomer species and plasma conditions. Among many samples, butadiene plasma polymer coated by a suitable plasma process showed excellent corrosion resistance. In order to make clear the cause of the variation, the following two investigations were performed: (1)Plasma Exposure Degree during the coating was introduced as a process parameter and (2) ESCA was utilized to find the atomic composition and the structure of plasma coating. The low PED process and low oxygen content at the bottom of the plasma polymer layer corresponded to excellent resistance. It was the oxygen atoms from Co-Ni-O that gave rise to poor corrosion resistance of plasma polymer coated samples.