Tadao Tokushima

Perpendicular magnetic media by anodic oxidation method and their recording characteristics

Magnetic alumite films containing electrodeposited Ni, Co and Fe were successfully prepared by employing an additional new process in the conventional anodic oxidation method in order to obtain suitable perpendicular coersive force below 1000 Oe. By this new process, the diameter of the micropores in the oxide layer was widened above 400 A. The recording characteristics of the 5.25 inch rigid disks were evaluated using a Mn-Zn ferrite ring head with a gap length of 0.5μm. A recording density D50 of 42 kBPI was obtained for the disk with a media thickness of 1.5μm and a coercivity of 950 Oe. The output voltage was 1.2μ Vpp / μm. turn at 20 kBPI. Higher recording density of D50 was expected for the disk with a media thickness below 1.5 μm. It was shown that the present medium exhibit higher potential for recording than a conventional plated medium at high recording density region.

Alumite disc using anordic oxidation

Perpendicular magnetic alumite discs were obtained using an anodic oxidation method.The additional new pore widening process was effective to control the coercive force. The electro-deposited fine iron needles were single crystals and the growth direction was [110]. The recording characteristics of 3.5 and 5.25 inch rigid discs were evaluated. A recording density D 50 of 50 KBPI was attained for the disc with a media thickness 1.5 µm. The environmental test under an atmosphere of of 40 °C 90 % R. H. over 1000 hr affirmed the stability of the alumite disc with 250A SiO 2 overcoat.

Microtribology of alumite disc using anodic oxidation

Magnetic alumite disks were fabricated using an anodic oxidation method. An additional chemical texture process was effective in improving tribological properties. The recording characteristics of 10-, 20-, and 30-nm-textured disks were evaluated. A recording density of 50 kb/in was attained at 5 MHz and 5 m/s relative speed. Environmental tests were carried out, with excellent results. >

Perpendicular magnetic flexible disc by anodic oxidation

Flexible alumite discs were prepared and their recording characteristics and wear resistance is reported. To study the surface roughness of alumite film, single-crystal Al platelets with different crystallographic orientations were prepared and anodic oxidized. The surface smoothness of these anodized films was better in the order [111]>[110]>[100]. For a flexible-disc substrate, >99.999%-pure Al was sputtered onto 50- mu m-thick PET film at a substrate temperature of 80 degrees C. The sputtered film was oriented favorably with [111]. After Fe was electrodeposited in the pores of 2- mu m-thick anodized Al film, it was polished to a thickness of 1 mu m. To test wear durability, the surface of the alumite layer was slightly etched and applied with liquid lubricant. A recording density D/sub 50/ of 60 kB/in. was obtained, together with a wear resistance of five million head passes. >

Recording and tribological properties of CoNi magnetic films on chemically textured aluminum rigid disk substrates (abstract)

In a rigid disk a very smooth surface is desirable for high density recording, while it tends to stick to the magnetic head. To avoid this difficulty, the mechanical texturing (M/T) is widely used. Unfortunately very low flying height can’t be achieved with the M/T. To improve the flying height, authors have developed a new texturing process using anodically oxidized aluminum substrates named chemical texturing (C/T).1 Aluminum anodic oxide films have a regularly arranged honeycomb structure and uniform and roughness‐controlled surfaces were formed by etching process of chemical texturing. In the present research, the relation between the recording and tribological properties and the etching conditions were investigated. On C/T substrates Cr, a longitudinal magnetic layer CoNi, C were sputtered in an inline sputtering equipment. The surface of the sputtered layer was flat (Ra<5 A) and uniform. Magnetic and electrical properties (coercive force, squareness, over write, modulation and so on) were examined. ...