Sumitomo Special Metals Co., Ltd.

Tsunekazu Saigo

Osamu Yamashita

Nobuhiro Sadatomi

Seiichi Kohara

Masao Noumi

Hiroshi Hashikawa

Hirokazu Kitayama

Ken Makita

Masahiro Asano

Shunichi Haruyama

A thermoelectric conversion material is formed of a polycrystal structure of crystal grains composed of a silicon-rich phase, and an added element-rich phase in which at least one type of added element is deposited at the grain boundary thereof, the result of which is an extremely large Seebeck coefficient and low thermal conductivity, allowing the thermoelectric conversion rate to be raised dramatically, and affording a silicon-based thermoelectric conversion material composed chiefly of silicon, which is an abundant resource, and which causes extremely low environmental pollution.

Thermoelectric conversion material and method of producing the same

A silicon-based polycrystal powder, which contains no more than 30 at % Ge, C, Sn, or another such element that does not generate carriers as well as an added element that does generate carriers, and which has a crystal structure including crystal grains made up of at least 80 at % silicon, and a grain boundary phase where at least one type of said added element is precipitated at the boundary of said crystal grains, is mixed with a clathrate compound powder with low thermal conductivity and electrical resistivity, and this mixture is subjected to hot compression molding, the product of which has a composite structure in which the particles of the clathrate compound polycrystals are disposed around the particles of the silicon-based polycrystals.

Thermoelectric conversion material, and method for manufacturing same

A silicon based conductive material based on a semiconductor silicon and having an electric resistivity of 10 (&OHgr;&middot;m) or less at ambient temperature which has been unattainable heretofore, while facilitating production and handling. An electric resistivity of 10 (&OHgr;&middot;m) or less, which is common for conductors can be realized by adding relatively large quantities of various kinds of elements to silicon. The conductive material can be provided in a semiconductor silicon substrate in a desired pattern by ion beam implantation and patterning. It can be employed not only in the form of a substrate, a rod or a wire, but also in the form of fine particles dispersed in a resin or glass to be employed in various applications requiring conduction, including a conductive sheet material.

Silicon based conductive material and process for production thereof

Manufacture by rolling silicon steel having a silicon content of 3 wt % or greater and by rolling thin sendust sheet is implemented by powder metallurgical fabrication using powder as the starting raw material, and the average crystal grain size of the sheet-form sintered body or quick-cooled steel sheet is made 300 pm or less, whereby intra-grain slip transformation occurs after slip transformation in the grain boundaries, wherefore cold rolling is rendered possible. In addition, a mixture powder wherein pure iron powder and Fe&mdash;Si powder are mixed together in a prescribed proportion is fabricated with a powder metallurgy technique, and an iron-rich phase is caused to remain in the sintered body, whereby cold rolling is possible using the plastic transformation of those crystal grains. Furthermore, when a minute amount of a non-magnetic metal element such as Ti, V, or Al, etc., is added beforehand, it becomes easy to make the iron-rich phase and silicon-rich phase enter into solid solution during annealing, crystal grain growth can be promoted, the magnetic properties of the fabricated steel sheet become roughly equivalent to those of conventional ingot material, and silicon steel sheet exhibiting outstanding magnetic properties can be fabricated.

Method for producing high silicon steel, and silicon steel

The purpose of this invention is to present fabrication methods and equipment for granulated powders whereby, the reaction between the R--Fe--B-type or R--Co-type rare earth containing alloy powders and the binder is controlled, the residual oxygen and carbon content of the sintered products after sintering is reduced, and whereby it is possible to obtain isotropic or anisotropic granulated powders having good powder flowability and lubrication properties when molding. After stirring a slurry of rare earth containing alloy powders formed by adding a binder consisting of water and at least one of either methyl cellulose, polyacryl amide or polyvinyl alcohol, and mixing, oriented liquid droplets are formed by applying a magnetic field to the slurry to orientate the said powder particles and spraying within the chamber of a spray dryer apparatus. By instantaneously dry solidifying these anisotropic granulated powders, it is possible to fabricate spherical granulated powders with good magnetic properties and a high flowability whereby the flowability and lubrication properties of the powder at the time of compression molding are improved, as well as improving the molding cycle and the dimensional precision of the molded product.

Fabrication methods and equipment for granulated powders

The purpose of this invention is to present fabrication methods and equipment for granulated powders whereby, the reaction between the R-Fe-B-type or R-Co-type rare earth containing alloy powders and the binder is controlled, the residual oxygen and carbon content of the sintered products after sintering is reduced, and whereby it is possible to obtain isotropic or anisotropic granulated powders having good powder flowability and lubrication properties when molding. After stirring a slurry of rare earth containing alloy powders formed by adding a binder consisting of water and at least one of either methyl cellulose, polyacryl amide or polyvinyl alcohol, and mixing, oriented liquid droplets are formed by applying a magnetic field to the slurry to orientate the said powder particles and spraying within the chamber of a spray dryer apparatus. By instantaneously dry solidifying these anisotropic granulated powders, it is possible to fabricate spherical granulated powders with good magnetic properties and a high flowability whereby the flowability and lubrication properties of the powder at the time of compression molding are improved, as well as improving the molding cycle and the dimensional precision of the molded product.

The object of the invention is to provide a manufacturing method of a complex shaped R--Fe--B type sintered anisotropic magnet improved the moldability of injection molding and preventing the reaction between R ingredients and binder and controlled the degradation of magnetic characteristics due to residual carbon and oxygen. Utilizing the R--Fe--B type alloy powder or the resin coated said alloy powder, and methylcellulose and/or agar and water, instead of the usual thermoplastic binder, it is mixed and injection molded. The molded body is dehydrated by the freeze vacuum dry method to control the reaction between R ingredients and of the R--Fe--B alloy powder and water; furthermore, by administering the de-binder treatment in the hydrogen atmosphere, and sintering it after the dehydrogen treatment, residual oxygen and carbon in the R--Fe--B sintered body is drastically reduced, improving the moldability during the injection molding to obtain a three dimensionally complex shape sintered magnet.

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Matsubara, Japan

Tsunekazu Saigo