Specialized metallurgical processes – compositions for use therei – Compositions – Consolidated metal powder compositions
Patent
1994-06-17
1996-06-25
Walsh, Donald P.
Specialized metallurgical processes, compositions for use therei
Compositions
Consolidated metal powder compositions
75228, 75245, 75252, 75253, 75255, B22F 900
Patent
active
055296033
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to alloy powders for a bond magnet which can be molded into various shapes, and and particularly to alloy powders for a bond magnetic having superior temperature characteristics, bond magnet.
BACKGROUND ART
A bond magnet is manufactured by molding a compound prepared by mixing and kneading magnetic alloy powders of desired compositions with resins, a flame retardant and so on, into various shapes by means of injection molding, compression molding and extrusion molding, so that thin and complicated shapes can be easily manufactured and uniform characteristics obtained without cracks and chips. Such magnets are widely used in magnetic circuits of electronic components, in audio equipment, OA equipment and the like.
Conventionally, a ferrite magnet powder and a rare earth magnet powder are generally used as the magnet powders for the bond magnet, and alnico magnet alloy powder is also used in a focusing magnet for focusing electronic beams and in color adjusting convergence in picture tube in television or display Braun tubes, because of its (1) superative temperature characteristics, (2) a higher saturated magnetic flux density than the ferrite magnet powder, and superior oxidation resistance and weatherproof as compared with the rare earth magnet powder. Such powders are furthermore low in cost.
As the alnico magnet, alnico 8 having a coercive force of 1000 Oe or more and alnico 5 having a coercive force of about 500 to 700 Oe are well known, both having a low temperature change of magnet characteristics of 0.05%/.degree.C. or less.
The inventor has previously proposed bond magnets of alnico 5 and alnico 8 (Japanese Patent Application Laid Open No. Hei 4-239103), and an alnico bond magnet is also disclosed in the Japanese Patent Application Laid Open Nos. Hei 3-239306 and Hei 3-259502.
However, since the Alnico type magnet alloys consisting of alnico 5 and alnico 8 all contain a large amount of Co, i.e., about 25% to 40%, there was the possibility of high product cost and uncertainty in supply of raw materials.
Also, though fire resistance is required a bond magnet used in domestic appliances and in OA equipment, some products using a bromic flame retardant have the possibility of producing dioxine having a toxicity at the time of combustion, thus the regulation of its use is being studied in U.S.A. and Europe.
It is an object of the present invention to provide alloy powders for bond magnet which do not contain cobalt, which is scarce in resources, and is composed mainly of Fe-Ni-Al-Cu having good temperature characteristics, and to provide a bond magnet containing a flame retardant which is safe to dispose and at the time of combustion such as a fire.
SUMMARY OF THE INVENTION
In the present invention, as a result of various studies made on alloy compositions which do not contain precious Co such as alnico 5 and alnico 8 as a bond magnet used, for example, in convergence which is used, for correcting beams of picture tubes in the color televisions and display Braun tubes, while making a good use of low temperature coefficient characteristics of the magnet characteristics, we found that it is possible to use as same as the costly Co alnico types, when pulverized into desired particles at the specific compositions substantially containing no Co, and as a result of various studies on blending for fire resistance as the bond magnet, by containing a necessary amount of specific flame retardants, the bond magnet having the fire resistance qualified by a combustion test of UL-94 Vo, and having little possibility of exhausting toxic substances such as dioxine can be obtained.
The alloy powders for bond magnet of the present invention is characterized by containing 10 wt % to 16 wt % Al, 23 wt % to 33 wt % Ni, 2 wt % to 8 wt % Cu, less than 5 wt % of one or two kind of Ti, Nb, and balance Fe and unavoidable impurities, and by having an isotropy and mean particle sizes of 10 .mu.m to 200 .mu.m.
The present invention also proposes, in the above-mentioned configurat
REFERENCES:
patent: 5015307 (1991-05-01), Shimotomai et al.
patent: 5213631 (1993-05-01), Akioka et al.
patent: 5227723 (1993-07-01), Hirai et al.
patent: 5240627 (1993-08-01), Mohri et al.
patent: 5256326 (1993-10-01), Kawato et al.
patent: 5300156 (1994-04-01), Mohri et al.
Hurukawa Toshihiro
Kitayama Hirokazu
Nishino Yoshihiko
Yamashita Michio
Greaves John N.
Sumitomo Special Metals Company Limited
Walsh Donald P.
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