Sumitomo Special Metals Co., Ltd.

Nippon Tungsten Co., Ltd.

Sumitomo Special Metal Co. Ltd.

Yoshiaki Katsuyama

Toshiaki Wada

Junichi Nakaoka

Michito Miyahara

Mitsuhiko Furukawa

Masaharu Shiroyama

Takashi Kitahira

Kiyohito Misumi

A sintered material for recording/reading (particularly magnetic) head slider is produced by:

Process for the production of magnetic head sliders

A grooved magnetic substrate including an alumina film layer having a Knopp hardness of 600 kg/mm.sup.2 to 1200 kg/mm.sup.2 charged in at least one groove formed in a surface of a magnetic substrate. The magnetic substrate may be Mn-Zn or Ni--Zn base ferrite. The alumina film layer is formed by sputtering.

Grooved magnetic substrates and method for producing the same

Magnetic head sliders, materials therefor, and the process for the

An improved magnetic recording disc comprising: a substrate member of an alumina-based ceramic material having micropores of 5 .mu.m or below and having a relative theoretical density of 90% or higher; a glass coating layer of a thickness of 3 to 200 .mu.m with a surface roughness (R.sub.z) of 180 angstroms or below, and being free from micropores and strain; a magnetic thin film formed on the surface of the glass coating layer; and a protective film formed thereon. A process for production of the magnetic recording disc comprises: forming a glass coating layer to a thickness of 5 to 220 .mu.m on the surface of an alumina-based ceramic substrate having micropores of 5 .mu.m or below and a relative theoretical density of at least 90%; then subjecting the glass coating layer to mechanochemical polishing to a layer thickness of 3 to 200 .mu.m, to make free from micropores and strain, and to have a surface roughness (R.sub.z) of 180 angstroms or below; and further coating the surface of the glass coating layer with a magnetic thin film and a protective film.

Magnetic recording disc and process for producing the same

A grooved magnetic substrate including an alumina film layer having a Knoop hardness of 600 kg/mm.sup.2 to 1200 kg/mm.sup.2 charged in at least one groove formed in a surface of a magnetic substrate. The magnetic substrate may be Mn-Zn or NiZn base ferrite. The alumina film layer is formed by sputtering.

A substrate member for recording disk characterized in that a glass coating film is provided on an alumina base ceramic material having micropores of no larger than 5 microns and a relative theoretical density of no less than 96%, said glass coating film having a surface roughness of no more than 80 angstroms, being substantially pore-free and strain-free on the surface, and having a thickness of 0.3 to 200 microns and a relative difference of no more than 10.sup.-6 /deg in the coefficient of thermal expansion with respect to said base material.

Recording disk substrate members and process for producing same

A substrate member for recording disks comprises a sputtered film of Al.sub.2 O.sub.3, SiO.sub.2 and/or Si.sub.3 N.sub.4 on the surface of an alumina base ceramic material having therein micropores of no more than 5 microns and a relative theoretical density of no less than 96% said sputtered film having a surface roughness of no more than 80 angstroms, being substantially pore-free and strain-free on the surface, and having a thickness of 0.3 to 30 microns.

Substrate members for recording disks and process for producing same

A composite substrate for a thin-film magnetic head comprises a substrate material, and an insulating oxide film formed thereon, and defining a smooth and stress-free surface having a surface roughness not greater than 50 .ANG.. A film of a magnetic material having improved magnetic properties may be formed on the surface of the oxide film.

Growing community of inventors

Muro, Japan

Yoshiaki Katsuyama