Sumitomo Metal Industries, Inc.

Sumitomo Special Metals Co., Ltd.

Nippon Paint Compnay, Ltd.

Masakazu Ohkita

Wataru Takahashi

Nobushige Hiraishi

Yoshihisa Kishimoto

Yutaka Matsuura

Naoyuki Ishigaki

Osamu Yamashita

Iwao Sumiyoshi

Tetsuzo Arai

Yoshiyuki Hashimasa

Ryoii Ishihara

Koichi Yamada

Manasori Yoshiiwa

The object of the present invention is to provide rare-earth system sintered magnets such as R&mdash;Fe&mdash;B system or R&mdash;Co system having excellent magnetic properties, unique configuration of a small size, thin wall thickness and intricate geometry. With the method for preparing the present invention, a granulation of alloy powders can be achieved easily, a chemical reaction between rare-earth system and binder substances can be suppressed, so that the residual oxygen and carbon levels in the sintered products can be reduced. Moreover, by this production method, the flowability and lubricant capability during the forming process can be improved. The dimension accuracy and productivity are also enhanced. A certain type of binder is added to rare-earth alloy powders and kneaded into a slurry state. The slurry is then formed into granulated powders by spray-dryer equipment. The thus granulated powders are molded, and sintered through a powder metallurgy technique.

Method for preparing rare-earth system sintered magnet

To a fine R-Fe-B alloy powder comprised predominantly of 10-30 atomic % of R (wherein R stands for at least one elements selected from rare earth elements including yttrium), 2-28 atomic % of B, and 65-82 atomic % of Fe in which up to 50 atomic % of Fe may be replaced by Co, at least one boric acid ester compound such as tributyl borate is added as a lubricant in a proportion of 0.01%-2% by weight and mixed uniformly before, during, or after fine grinding of the alloy powder. The resulting powder mixture is compacted by compression molding in a magnetic field and the green compacts are sintered and aged. Compression molding can be performed continuously without need of mold lubrication, and the resulting magnets have improved magnet properties with respect to residual flux density, maximum energy product, and intrinsic coercive force.

Powder mixture for use in compaction to produce rare earth iron sintered

To a fine R--Fe--B alloy powder comprised predominantly of 10-30 atomic % of R (wherein R stands for at least one element selected from rare earth elements including yttrium), 2-28 atomic % of B, and 65-82 atomic % of Fe in which up to 50 atomic % of Fe may be replaced by Co, at least one boric acid ester compound such as tributyl borate is added as a lubricant in a proportion of 0.01%-2% by weight and mixed uniformly before, during, or after fine grinding of the alloy powder. The resulting powder mixture is compacted by compression molding in a magnetic field and the green compacts are sintered and aged. Compression molding can be performed continuously without need of mold lubrication, and the resulting magnets have improved magnet properties with respect to residual flux density, maximum energy product, and intrinsic coercive force.

A radiation curable primer coating composition is provided comprising (a) a reaction product of an epoxide compound and an ethylenically unsaturated monocarboxylic acid, (b) a compound of the formula: ##STR1## wherein R is hydrogen atom or methyl, A is a C.sub.2 -C.sub.4 alkylene group, and n is 0, 1 or 2; and (c) a compound having at least one epoxy group per molecule. The composition may be applied onto a steel substrate and cured by the irradiation of an actinic radiation for improving properties of subsequently applied polyolefin coatings thereon.

Radiation curable primer coating compositions

Growing community of inventors

Osaka, Japan

Masakazu Ohkita