Metal powder with nano-composite structure and its production method using a self-assembling technique

Abstract

Methods, apparatuses and systems for producing powder particles of extremely small, highly uniform spherical shape and high sphericity, composed of metal including single metals and alloys, including nanocomposite structures, using a self-assembling procedure. The invention further includes the produced spherical particles. The metal spherical particles are produced whereby molten metal, alloys or composites are directed onto a fast-rotating disk in an atmosphere containing one or more inert gases and small amounts of an oxidizing gas and the molten metal drops are dispersed as tiny droplets for a predetermined time using centrifugal force within a cooling-reaction gas, and then cooled rapidly to form solid spherical particles. The spherical particles comprise a crystalline, amorphous or porous composition, having a size of 1-300 μm±1% with a uniformity of size being≦60-70% and a precise spherical shape of less than or equal to ±10%.

Description

FIELD OF THE INVENTION [0001] This invention concerns processes, apparatuses and systems for producing powder of extremely small, highly uniform spherical shape, having high sphericity, and composed of metal including single metals and alloys, including nano-composite structures, using a self-assembling procedure. The present invention further includes the powder particles produced by the processes, apparatuses and systems of the present invention. The powder particles may be used for example, as the starting materials of magnets, catalysts, electrodes, batteries, heat insulators, refractory materials, and sintered metals. For instance, the powders of the rare earth-iron-boron (R—Fe—B) alloy with the nanocomposite structure of the present invention may be used a starting material for producing a sintered magnet or bonded magnet having excellent magnetic characteristics. BACKGROUND OF THE INVENTION [0002] Various kinds of the powders of metals, metal oxides, metal nitrides, metal sil...

AI Technical Summary

Benefits of technology

[0008] The nanocomposite structures provide for a permanent magnet with excellent magnetic properties employing nano-sized, non-magnetic material, which is a rare earth oxide, ROx, R2O3, RO, RO2, such as neodymium oxide or praseodymium oxide, (or MOx where M is a minor metal as exemplified below) that is incorporated at the inside of ferromagnetic grains, such as R—Fe—B, and / or at their grain boundaries. Usually, Nd is preferably employed as R, and rare earth elements such as Pr is favorably employed. Nd2O3, RO and RO2 are preferably used in the present invention. The resulting novel nanostructure consists of micro-sized ferromagnetic phase and novel nano-sized nonmagnetic phase providing for the overall novel nanocomposite structure of the present invention.

Problems solved by technology

Such powders commonly suffer from poor uniformity of composition, shape, granularity and for spherical powders, poor sphericity (degree of roundness).

While of possibly uniform composition, such particles are of poor uniformity in size and shape, and of course are not of spherical shape.

Moreover, it is difficult to obtain a nanocomposite structure using mechanical pulverization for the production of fine powders.

Conventional apparatuses and methods can not result in a nanocomposite magnetic material at all, and certainly not result in the present tiny spherical powders by a self-assembly technique.

Though this magnet shows excellent magnetic properties, the latent ability of the RFeB or RFeBA tetragonal compounds have not been exhibited fully.

Such typical atomization apparatuses produce spherical powders having poor sphericity, limited microdimensions and poor uniformity of composition and shape.

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