Nkk Corporation

Nippon Kokan Kabushiki Kaisha

Nippon Mining Co., Ltd.

Other

Fuji Electric Co., Ltd.

Hiroyoshi Suenaga

Kuninori Minakawa

Hideaki Fukai

Chiaki Ouchi

Hideo Sakuyama

Toshio Sakiyama

Masanori Ohmura

Iwao Ida

Hiroyoshi Takeuchi

Hitoshi Nagashima

Kenji Morita

Takeshi Ito

Masahiko Naoe

Atsushi Ogawa

Hiroshi Kibe

Noboru Kurata

Masakazu Niikura

Yohji Kohsaka

Yoko Okano

Shinichiro Otaka

Naoto Kohshiro

Yoji Kohsaka

Chiaki Ohuchi

Misao Ishikawa

Ichiro Sawamura

Michio Hanaki

Masakuni Takagi

Ichiroh Sawamura

Michio Hanai

Hideo Takatori

The object of the present invention is to provide titanium discs to be used as high-density read-while-write magnetic discs. Further object of the present invention is to provide said titanium discs coated with a non-magnetic plated layer. Titanium discs to be used as magnetic discs which satisfy the above object have the following structures: A titanium disc to be used as magnetic disc having the mean height of the peaks from the center line, R.sub.a, of 0.0002 .mu.m to 0.0060 .mu.m and pits on its surface of 25 .mu.m or less in diameter or 5 .mu.m or less in depth. Further, said titanium disc to be used as a magnetic disc is coated with a non-magnetic plated layer with a thickness of 0.09 .mu.m to 5 .mu.m. Moreover, a titanium disc that is most suitable to be used as a magnetic disc is the titanium disc provided with a plated layer of 30/100 or less in a knife-cut peeling test.

Titanium discs useful for magnetic discs

A magnetic disk substrate having a composition wherein (V/13)+(Fe/20)+(Cr/17)+(Ni/31)+(Co/23) are no greater than 0.010%, Rem+Si+B+W are no greater than 0.015% (where Rem denotes rare earth metals), 0+2N+0.75C are no less than 0.03% and no greater than 0.5%, and the remainder consists substantially of Ti, all % being weight %.

Magnetic disk substrate

A method of manufacturing a magnetic disk substrate made of titanium, in which chemical etching is performed on a titanium disk for magnetic disk substrate, thereby removing a surface portion thereof having a thickness of at least 2 nm, and the new surface of the titanium disk, formed by the chemical etching, is anodized, thereby forming anodized film on the titanium disk.

Method of manufacturing a magnetic disk substrate of titanium

A method of manufacturing a titanium alloy magnetic disk substrate comprising (a) cold-rolling an alloy plate at a rolling ratio of no less than 30%, the alloy plate comprising 0.5 wt. % to 1.0 wt. % of Mo and containing oxygen, nitrogen and carbon in amounts such that O+2N+0.75C is from 0.03 wt. % to 0.5 wt. % of the titanium alloy, and the balance being Ti, wherein O is the wt. % of oxygen, N is the wt. % of nitrogen and C is the wt. % of C to form a magnetic disk substrate material and then (b) thermal-flattening the magnetic substrate material from step (a) under a condition defined as follows:

Method of manufacturing a magnetic disk substrate

A method for lapping two surfaces of a titanium disk comprises inserting loosely a titanium disk to be lapped into an opening in a disk-type carrier, the carrier rotating and revolving between an upper surface plate and a lower surface plate which are held in parallel with each other and which applies lapping pressure to the titanium disk, feeding abrasives between the surface plates and the titanium disk and satisfying the following relationship between thickness t (mm) of the titanium disk and thickness T (mm) of the carrier:

Method for lapping two surfaces of a titanium disk

According to a mirror surface polishing process of the present invention, it is possible to produce Ti-made magnetic disc substrate which have the excellent flatness degree and surface roughness in that the average roughness is not more than 0.05 .mu.m and the flatness degree of the outer periphery is not more than 0.15 .mu.m.

Method for mirror polishing of ti-made magnetic disk substrate

After the surface roughness of a titanium substrate is set to be R.sub.max .ltoreq.0.08 .mu.m, a hardened layer having a hardness of H.sub.v .gtoreq.250 is formed thereon to have a thickness of 50 to 250 .mu.m by sputtering, thereby manufacturing a titanium magnetic disk substrate.

Method of manufacturing titanium magnetic disk substrate

A magnetic disk substrate composition 0.5 wt % to 1.0 wt % of Mo, 0.03 wt % to 0.5 wt % of O+2N+0.75C, and a balance of Ti. The alloy sheet having a composition of above range is cold-rolled at a rolling ratio of 30% or more to form a magnetic disk substrate material, and the material is thermal-flattened under the following condition:

Magnetic disk substrate and method of manufacturing the same

A method for manufacturing titanium clad steel plate by forming a slab assembly having an alloy steel substrate, a titanium metal or alloy cladding on said substrate and a Ni-Cr alloy foil or film having opposed surfaces between said alloy steel and said cladding. The Ni-Cr alloy foil or film has one surface in surface contact with the cladding and the opposed surface in surface contact with the alloy steel substrate. The Ni-Cr alloy contains 32.5 to 40 wt. % Cr and 55 to 65 wt. % Ni. The slab assembly is heated at a temperature of 850.degree. to 1010.degree. C. The heated slab assembly is hot rolled with a reduction ratio of 30% or more to form the titanium clad steel plate.

Method for manufacture titanium clad steel plate

Titanium magnetic disk substrates are manufactured by preparing a base by stripping not less than 5 .mu.m from the surface layer of a titanium cold-rolled plate, and then forming a film of not less than 5 .mu.m consisting of 1 or more non-magnetic transition metal elements belonging to Groups IVA, VA, VIA, VIIA and VIIIA of the Periodic Table, on the surface of this base.

Method of manufacturing a titanium magnetic disk substrate

The invention provides a titanium alloy having improved superplastic forming characteristics and mechanical characteristics. A titanium alloy having superplastic forming characteristics consisting essentially of about 5.5 to 6.75 wt. % Al, 3.5 to 4.5 wt. % V, 0.01 to 0.2 wt. % O, 0.85 to 3.15 wt. % Fe, 0.85 to 3.25 wt. % Mo, with 2.times.Fe wt. %+Mo wt. % being from 3 to 8, and balance titanium; said alloy containing .alpha.-crystals having a grain size below about 6 .mu.m in diameter. The Fe and Mo act as .beta.-stabilizing elements and contributing elements to lowering the beta transus and to the improvement of the superplastic characteristics.

Titanium base alloy for superplastic forming

A .beta. type titanium alloy material is passed through processes and heating treatments of cold working--intermediate solution treatment--final cold working--final solution treatment--aging. In this process, a structure, which has been provided with strains by the cold working performed prior to the final cold working, will be changed into a recrystallized structure by carrying out the intermediate solution treatment, where uniform and fine micro substructure of dislocations, remain with grains. If such an intermediate solution-treated material is processed with a slight cold working by the final cold working and further with the solution treatment, only a recovery phenomenon progresses, and it is possible to provide such a micro substructure containing more uniform and finer dislocation network not only in grains but also in grain boundaries. Therefore, in the aging, expedition of precipitation and uniform distribution of .alpha. crystals will be realized in the grains and grain boundary regions, and intergranular cracking is difficult to take place, and alloy materials having high strength and high ductility may be produced.

Method for producing beta type titanium alloy materials having excellent

For producing titanium clad steel plates by hot rolling, oxide of Mo or V is used as an intermediate material, and a slab assembly is formed with ferrous bases and titanium cladding materials. At least one side of cladding surfaces of the bases and the cladding materials is coated with an oxide of Mo or V of 20 to 300 g/m.sup.2, and an interior of the slab assembly is air-discharged less than 10.sup.-1 torr, and the slab assembly is heated at temperatures between a melting point of the employed oxide plus 50.degree. C. and 1050.degree. C. and undertaken with hot rolling.

Method of producing titanium clad steel plate by hot rolling

A method for producing Ti alloy plates, comprising heating an .alpha.+.beta. Ti alloy ingot to a temperature within the .alpha.+.beta. two phase range, forging or rolling said heated alloy ingot to reduce it more than 30% whereby strain energy accumulates in said ingot as it is being reduced, and reheating said reduced ingot containing said accumulated strain energy to a temperature of the .alpha.+.beta. phase range and then hot rolling said reheated reduced ingot so that it is further reduced in an amount more than an additional 30% whereby said accumulated strain energy accelerates recrystallization during said hot rolling to produce a uniform alloy structure, said heating and reheating being carried out in an atmosphere having not more than 0.02 atm oxygen partial pressure.

Method of producing Ti alloy plates

A method of manufacturing a rolled titanium alloy sheet comprises breaking down an .alpha. or .alpha.+.beta. titanium alloy ingot into a slab, working the slab in sequential stages of

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Tokyo, Japan

Hiroyoshi Suenaga