Tetsuo Mizumura

The Analysis of Chemical State of Obliquely Evaporated Co-Ni-O Film by Auger Electron Spectroscopy

Obliquely evaporated Co-O and Co-Ni-O films show different coercivity dependences on saturation magnetization. To clarify the origin of this difference, we introduced numerical analysis in Auger electron spectroscopy and analyzed the chemical state (metal or oxide) of the Co-Ni-O magnetic layer. In the Co-Ni-O magnetic layer, cobalt was oxidized preferentially compared to nickel. Therefore the compositional ratio of metallic Co to Ni in the magnetic layer was assumed to be different from that of source material. This preferential oxidation of cobalt was considered to be the cause of the difference in coercivi ty dependences on saturation magnetization between Co-O and Co-Ni-O.

Improvement of durability and corrosion resistance of metal evaporated tape with chemically deposited SiO/sub x/ overcoat

To improve the reliability of metal evaporated tape (ME tape), SiO/sub x/ overcoat was investigated. The durability of ME tape overcoated with SiO/sub x/ was greatly improved by lubricating with C/sub 18/H/sub 37/OP(H)(O)OH (mono octadecyl phosphite: MOP), which showed more than 10 hours life time in a still mode durability test (relative speed of head to media: 11.3 m/s). Since MOP was solid at room temperature, adhesion did not occur and friction force during the test reduced by 25% compared with perfluoropolyether liquid lubricant. Corrosion of ME tape was prevented by SiO/sub x/ overcoat prepared by plasma enhanced chemical vapor deposition (PECVD). Water transmission rate of PECVD-SiO/sub x/ was one tenth that of physically deposited SiO/sub x/, which suppressed surface corrosion of ME tape in an atmosphere of 60/spl deg/C 90%R.H. and of 4 ppm SO/sub 2/ (40/spl deg/C 80%R.H.).