Shin-etsu Chemical Co., Ltd.

Shin-etsu Chemical C O., Ltd.

Yukihiro Kuribayashi

Harukazu Maegawa

Shogo Kamiya

Shintaro Tanaka

Masatoshi Ishii

Yoshifumi Nagasaki

Hajime Kitamura

Hiroyuki Miyamoto

Masanobu Uchida

Hiroto Sugahara

Genji Noguki

Satoshi Shima

A coating tankprovided with a net belt passage opening is prepared, a slurry obtained by dispersing a rare-earth-compound powder in a solvent is continuously supplied to the coating tankto cause the coating tankto overflow, and a plurality of sintered magnet bodiesare arranged on a net belt conveyor, continuously conveyed horizontally thereon, and passed through the slurry in the coating tankvia the net belt passage opening, to apply the slurry to the sintered magnet bodies. The slurry is subsequently dried to continuously apply the powder to the plurality of sintered magnet bodies. As a result, the rare-earth-compound powder can be uniformly applied to the surfaces of the sintered magnet bodies, and the application operation can be performed extremely efficiently.

Method for producing rare-earth magnets, and rare-earth-compound application device

When a slurry s obtained by dispersing a rare-earth-compound powder in a solvent is applied to sintered magnet bodies m, and dried to remove the solvent in the slurry and cause the surfaces of the sintered magnet bodies to be coated with the powder, and the sintered magnet bodies coated with the powder are heat treated to cause the rare-earth element to be absorbed by the sintered magnet bodies, the sintered magnet bodies m are warmed or heated before the slurry s is applied. As a result, the rare-earth-compound powder can be efficiently and uniformly applied to the surfaces of the sintered magnet bodies.

A sintered magnet body is held in a grounded jig exhibiting excellent electrical conductivity, a rare-earth-compound powder is charged and sprayed on the sintered magnet body to electrostatically coat the sintered magnet body with the powder, and thus apply the powder to the sintered magnet body. The sintered magnet body having the powder applied thereto is heat treated to produce a rare-earth magnet. As a result, the rare-earth-compound powder can be uniformly applied to the surface of the sintered magnet body, and the application operating can be performed extremely efficiently.

Method for producing rare-earth magnet

When sintered magnet bodiesare held in a jighaving a rotational axis in the vertical direction, immersed in a slurryto apply the slurry thereto, rotated in conjunction with the jig to remove the surplus slurry on the surface of each of the sintered magnet bodies by centrifugal force, and subsequently dried to cause the surfaces of the sintered magnet bodies to be coated with a powder, the slurry is applied while the sintered magnet bodies are held such that no portion of any of the outer surfaces forming the contours of the sintered magnet bodies is orthogonal to the direction of the centrifugal force. As a result, the rare-earth-compound powder can be uniformly applied to the surfaces of the sintered magnet bodies.

When a slurryobtained by dispersing a rare-earth-compound powder in a solvent is applied to sintered magnet bodies, and dried to remove the solvent in the slurry and cause the surfaces of the sintered magnet bodies to be coated with the powder, and the sintered magnet bodies coated with the powder are heat treated to cause the rare-earth element to be absorbed by the sintered magnet bodies, the sintered magnet bodies having had the slurry applied thereto are dried by being irradiated with near infrared radiation having a wavelength of 0.8-5 &#x3bc;m, to remove the solvent in the slurry, and cause the surfaces of the sintered magnet bodies to be coated with the powder. As a result, the rare-earth-compound powder can be uniformly and efficiently applied to the surfaces of the sintered magnet bodies.

A method for producing rare-earth magnets is provided in which, when a slurryhaving a rare-earth-compound powder dispersed therein is applied to sintered magnet bodiesand dried to apply the powder thereto, the magnet bodiesare accommodated and conveyed in holding pocketsof a conveyance drumwhich rotates in a state of being partially immersed in the slurry, and, as a result, the magnet bodiesare immersed in the slurry, withdrawn from the slurry, and dried to apply the powder to the sintered magnet bodies. According to this production method, the powder can be uniformly and efficiently applied, wastage of the rare-earth compound can be effectively suppressed, and a reduction in the surface area of equipment for performing an application step can also be achieved.

Method for producing rare-earth magnets, and slurry application device

When a slurry in which a rare-earth-compound powder is dispersed is applied to sintered magnet bodiesand dried to apply the powder thereto, the sintered magnet bodiesare conveyed by a conveyerand made to pass through the slurryto apply the slurry to the sintered magnet bodies. Furthermore, a plurality of push-up members, which pass through insertion holesprovided in a conveyor belt, and protrude above the conveyor belt, are used to temporarily push up the sintered magnet bodies, and temporarily separate the conveyor beltand the sintered magnet bodies. As a result, the slurry can be efficiently applied, even mass production can be suitably dealt with, and the slurry can be uniformly and reliably applied to the entire surface of each of the sintered magnet bodies.

A fixed beamalong which magnet-body holding sectionsare consecutively provided is disposed so as to pass through a slurry. Sintered magnet bodies m placed in the magnet-body holding sectionsby movable beamsare conveyed by repeating an operation in which the sintered magnet bodies m are moved to the following magnet-body holding sections. While being conveyed, the sintered magnet bodies m are passed through the slurryto apply the slurry thereto, and are subsequently dried to remove a solvent in the slurry and affix a powder in the slurry thereto, and, as a result, the powder is continuously applied to the plurality of sintered magnet bodies. Accordingly, a rare-earth-compound powder can be uniformly applied to the surfaces of the sintered magnet bodies, and the amount of the slurry taken from a coating tank can be reduced to effectively decrease wasteful consumption.

A rare earth permanent magnet is prepared by immersing a portion of a sintered magnet body of R&#x2014;Fe&#x2014;B composition (wherein Ris a rare earth element) in an electrodepositing bath of a powder dispersed in a solvent, the powder comprising an oxide, fluoride, oxyfluoride, hydride or rare earth alloy of a rare earth element, effecting electrodeposition for letting the powder deposit on a region of the surface of the magnet body, and heat treating the magnet body with the powder deposited thereon at a temperature below the sintering temperature in vacuum or in an inert gas.

Preparation of rare earth permanent magnet

An electrodepositing apparatus is provided comprising an inner tank () filled with an electrodepositing solution, an outer tank (), a feedback means (), a rectifying member () disposed in the inner tank (), a means () for holding an article (p), a counter electrode (), and a power supply (). The electrodepositing solution is circulated in such a way that it overflows the inner tank and is fed back from the outer tank to the inner tank by the feedback means, the flow of the solution is rectified by the rectifying member to keep flat the solution surface in the inner tank, a selected portion of the article is immersed in the solution, and the coating agent is electrodeposited on the selected portion of the article.

Electrodepositing apparatus and preparation of rare earth permanent magnet

Provided is a hydrogen absorbing alloy powder for use in nickel-metal hydride storage batteries having a high capacity, excellent initial characteristics and a long life. Specifically provided is a process for the production of a hydrogen absorbing alloy powder which includes the steps of treating a hydrogen absorbing alloy powder with an acid solution, and subsequently treating the hydrogen absorbing alloy powder with a solution containing a condensed phosphoric acid having 2 to 20 phosphorus atoms per molecule and/or phytic acid, as well as an electrode formed of the hydrogen absorbing alloy powder produced by the above process. Also provided is a hydrogen absorbing alloy powder of the AB,type in which A is exothermic metal and B is endothermic metal, the hydrogen absorbing alloy powder being obtained by providing a hydrogen absorbing alloy in which A comprises a mixture composed of 20 to 50% by weight of Ce, 20 to 50% by weight of La, and the balance comprising rare earth elements other than Ce and La and inclusive of Y (yttrium), treating the hydrogen absorbing alloy powder with an acid solution, and further treating the hydrogen absorbing alloy powder with a solution containing a phosphorus compound, as well as an electrode formed of this hydrogen absorbing alloy powder.

Hydrogen absorbing alloy powder and electrodes formed of the hydrogen absorbing alloy powder

A method of producing a hydrogen absorbing alloy powder, which comprises a step of treating a pulverized hydrogen absorbing alloy with a solution comprising a condensed phosphoric acid having 2 to 20 phosphorus atoms, phytic acid or a mixture thereof; and a negative electrode using a hydrogen absorbing alloy powder produced by the aforesaid method, which can ensure high initial activity and high initial capacity in the nickel-hydrogen secondary battery provided therewith.

Method of producing hydrogen absorbing alloy powder, and electrode using

A method of producing a hydrogen absorbing alloy powder, which comprises a step of treating a pulverized hydrogen absorbing alloy with a solution comprising a conjugated unsaturated compound having at least 5 conjugated .pi. bonds and a molecular weight of at least 100 and, prior to the this step, optionally comprises a step of treating a pulverized hydrogen absorbing alloy with a mineral acid or alkali; and an electrode using a hydrogen absorbing alloy powder produced by the aforesaid method.

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Echizen, Japan

Yukihiro Kuribayashi