Specialized metallurgical processes – compositions for use therei – Compositions – Loose particulate mixture containing metal particles
Reexamination Certificate
2000-09-28
2002-08-13
Mai, Ngoclan (Department: 1742)
Specialized metallurgical processes, compositions for use therei
Compositions
Loose particulate mixture containing metal particles
C075S252000
Reexamination Certificate
active
06432159
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magnetic mixture, and more particularly, to a magnetic mixture of two or more kinds of soft magnetic material powders which are uniformly mixed with each other, which mixture is useful as a raw material for the production of products having the intended magnetic properties.
2. Prior Art
Powder magnetic cores are frequently used in a smoothing choke coil provided on the direct current output side of a switching regulator, a reactor of an active filter provided in an inverter controller, and the like.
The powder magnetic core is generally produced by adding a predetermined amount of an insulating binder such as water glass to a powder of a soft magnetic alloy having predetermined magnetic properties and by subjecting the resultant mixture to press molding.
As a raw material for a powder magnetic core, soft magnetic alloys such as an Fe—Si alloy, an Fe—Si—Al alloy and an Fe—Ni alloy are used. Pure iron, other than an alloy, having high saturation magnetization is also used.
In the preparation of these alloys, the aforementioned constituent elements are added to Fe serving as a base element in such a manner that a predetermined composition ratio is attained.
When the composition ratio of the constituent elements of the alloy varies, magnetic properties of the alloy also vary. At a particular composition ratio, there appears a significant point in magnetic properties of the alloy, i.e., a significant magnetic property, such that the saturation magnetization, permeability, magnetostriction, magnetic anisotropy constant or the like has a local maximum, a local minimum, or a value of substantially zero.
For example, in the case of the Fe—Si—Al alloy, when the composition ratio of Si or Al is varied, the degree to which the significant magnetic properties that manetostriction becomes substantially zero and the permeability has a local maximum are exhibited also vary. At the composition ratio where Si is 9.0 to 10.0% by weight and Al is 5.0 to 6.0% by weight, both the significant magnetic properties appear, and hence an alloy having the magnetostriction of substantially zero and a maximum value of permeability can be obtained. A representative example of such an alloy has the composition of Fe-9.5% Si-5.5%Al, which is a soft magnetic alloy generally called Sendust. By using this alloy, it is possible to produce a magnetic core having a small core loss.
In this manner, a soft magnetic alloy for use as a raw material for a powder magnetic core is prepared: to have a significant point in magnetic property by determining the composition ratio of the constituent elements in accordance with the intended properties of the powder magnetic core.
For example, among the Fe—Si alloys, there can be mentioned an Fe-6.5% Si alloy having the significant property that the magnetostriction is substantially zero. As the Fe—Si—Al alloy, Sendust having the above-mentioned composition can be mentioned. As the Fe—Ni alloy, an Fe-80% Ni-2% Mo alloy generally called PC permalloy can be mentioned, which has both the significant property that the magnetostriction is substantially zero and the significant property that permeability has a local maximum. As the Fe—Co alloy, there can be mentioned an Fe-49% Co-2% V alloy and an Fe-50% Co alloy, which are generally called permendur and exhibit the significant property that the saturation magnetization has a local maximum.
A powder magnetic core produced using a powder of Sendust has a low coercive force, achieving such properties that the core loss is reduced and the permeability is high. However, Sendust has low saturation magnetization, exhibiting low permeability when a large current flows therethrough. In some application fields, the powder magnetic core produced solely from Sendust may have unsatisfactory performance in practical use.
Recently, powder magnetic cores have been sometimes requested to have essential magnetic properties by retaining significant magnetic properties of the raw material, whereas magnetic properties other than essential magnetic properties may be maintained in the cores at individual grade levels. However, by use of the conventional raw material prepared to exhibit one significant property, the resultant powder magnetic core also exhibits one significant property. Thus, the above-mentioned demand cannot be met. For example, such a demand that the powder magnetic core must have a plurality of essential magnetic properties, e.g., core loss and saturation magnetization, or core loss and permeability, cannot be satisfied.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the present invention to provide a magnetic mixture in which, among the significant magnetic properties of a raw material (soft magnetic alloy) for a powder magnetic core to be produced, those significant magnetic properties which are required of the powder magnetic core are retained in the magnetic mixture, although unnecessary significant magnetic properties are permitted to be deteriorated.
It is another object of the present invention to provide a magnetic mixture which can be produced simply by uniformly mixing at least two kinds of soft magnetic material powders, at lower costs as compared to the conventional magnetic mixture, and which makes it possible to produce a powder magnetic core at a high degree of freedom of design.
To attain the above objects, the present invention provides a magnetic mixture (hereinafter, referred to as “magnetic mixture 1”) comprising at least two kinds of powders which are uniformly mixed with each other, wherein constituent elements of each of the powders have a particular composition ratio to exhibit a significant point in magnetic property. Magnetic properties of each of the powders are retained in the magnetic mixture, and the magnetic mixture exhibits, as a whole, a soft magnetic property.
Further, the present invention provides a magnetic mixture (hereinafter, referred to as “magnetic mixture 2”) comprising at least one kind of soft magnetic material powder whose constituent elements having a particular composition ratio to exhibit a significant point:in magnetic property; and at least one different kind of soft magnetic material powder which is uniformly mixed with the at least one kind of soft magnetic material powder, wherein magnetic properties of each of the powders are retained in the magnetic mixture, and the magnetic mixture exhibits, as a whole, a soft magnetic property.
Further, there are provided magnetic mixture 1 and magnetic mixture 2 each further comprising at least one insulating material which is uniformly mixed thereinto.
Furthermore, according to the present invention, a magnetic mixture is provided, which comprises two or three kinds of powders which are uniformly mixed with each other, wherein the powders are selected from the group. consisting of a powder of an Fe-(3.0±0.5)% Si alloy, a powder of an Fe-(6.5±0.5)% Si alloy and a powder of an Fe-(9.5±0.5)% Si-(5.5±0.5)% Al alloy. Further, a magnetic mixture is provided, which comprises the just-mentioned magnetic mixture of 70% by weight or more and a powder of pure iron of 30% by weight or less.
DETAILED DESCRIPTION OF THE INVENTION
First, a magnetic mixture 1 is described.
The magnetic mixture 1 is obtained by uniformly mixing together two or more kinds of soft magnetic material powders.
More specifically, as the soft magnetic material, a soft magnetic alloy is used, which must exhibit not only a soft magnetic property but also a significant point in magnetic property, i.e., a significant magnetic property, when its constituent elements have a particular composition ratio. Examples of such soft magnetic alloys include one that exhibits, when it has a particular composition, a significant property such that the magnetostriction or the magnetic anisotropy constant has a value of substantially zero, or the permeability has a local maximum or the coercive force has a local minimum, or the saturation magnetization has a local maximum.
More stri
Koyama Haruo
Saito Takanobu
Takemoto Satoshi
Yahagi Shin'ichiro
Yashiro Toshiaki
Daido Tokushuko Kabushiki Kaisha
Frishauf, Holtz Goodman, Langer & Chick, P.C.
Mai Ngoclan
LandOfFree
Magnetic mixture does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Magnetic mixture, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Magnetic mixture will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2884655