Hitachi, Ltd.

Yoshiteru Chiba

Takahiko Kato

Jiro Kuniya

Yoshihisa Kiyotoki

Mitsuo Chigasaki

Shizuo Matsushita

Michiya Okada

Hiroshi Satoh

Akira Sakamoto

Kazuhide Tanaka

Toshimi Matsumoto

Toshiya Doi

Yoshimi Yanai

Kimihiko Akahori

Akira Okayama

Tadaoki Morimoto

Kikuo Takeshima

A valve which is cobalt-free excellent in wear resistance and seizure resistance manufactured by forming valve seats for a valve disc and a valve body with a nickel base alloy in which silicide particles or boride particles of small particle size are finely dispersed, and the valve seat is bonded to the valve disc or the valve body by way of an insert material comprising a nickel base alloy of a lower melting point by transient liquid phase diffusion bonding.

Valve and manufacturing method thereof

In the joint construction of cobalt-based alloy, a cobalt-based alloy layer, in which granular or massive eutectic carbidedisperses, is joined to a metal of a base metalvia an insert metal layer. For the joint construction of cobalt-based alloy, liquid phase diffusion bonding is performed at a temperature of 1100&#xb0; C. for a retention time of 1 hour with an insert metal with a thickness of about 40 &#x3bc;m being interposed between the base metal, which is S45C carbon steel, and a cobalt-based alloy material which has granular or massive eutectic carbide with a grain size not larger than 30 &#x3bc;m in a matrix of cast structure and contains 1.03 wt % C, 29.73 wt % Cr, 3.86 wt % W, 2.59 wt % Ni, 2.67 wt % Fe, 0.59 wt % Si, and 0.07 wt % Mo, the balance substantially being Co. The cobalt-based alloy layerafter bonding contains granular or massive eutectic carbide.

Joint construction of cobalt-based alloy

In the joint construction of cobalt-based alloy, a cobalt-based alloy layerin which granular or massive eutectic carbidedisperses, is joined to a metal of a base metalvia an insert metal layerFor the joint construction of cobalt-based alloy, liquid phase diffusion bonding is performed at a temperature of 1100&#xb0; C. for a retention time of 1 hour with an insert metal with a thickness of about 40 &#x3bc;m being interposed between the base metal, which is S45C carbon steel, and a cobalt-based alloy material which has granular or massive eutectic carbide with a grain size not larger than 30 &#x3bc;m in a matrix of cast structure and contains 1.03 wt % C, 29.73 wt % Cr, 3.86 wt % W, 2.59 wt % Ni, 2.67 wt % Fe, 0.59 wt % Si, and 0.07 wt % Mo, the balance substantially being Co. The cobalt-based alloy layerafter bonding contains granular or massive eutectic carbide.

A valve is characterized by excellent corrosion and wear resistance and maintainability due to use of a bonding corrosion and wear proof alloy containing non-continuously distributed eutectic carbide on the sliding portions of various types of apparatuses and valves by diffusion bonding. This serves to improve the maintainability of a thermal and nuclear power plant and to provide a nuclear power plant using recirculating water, which ensures excellent working safety, in particular. The corrosion and wear proof alloy is characterized in that network-formed eutectic carbide in the alloy containing the cast structure base metal and eutectic carbide is formed into(multiple) granules or lumps having a particle size of 30 microns or less so that said eutectic carbide is non-continuously distributed.

Valve bonded with corrosion and wear proof alloy and apparatuses using said valve

The present invention provides a shaped superconductor article such as wire, tape or disk, comprising an oxide superconductor phase and a metal phase in a monolayered or multilayered form, the metal phase comprising a copper, iron, nickel or titanium base alloy containing 1 to 10% by weight of aluminum and having an oxygen-impermeable oxide film formed thereon, preventing the diffusion of oxygen from the oxide superconductor phase to the metal phase.

Ceramic superconductor article

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Hitachi, Japan

Yoshiteru Chiba