JPS58108713A - Manufacture of dust core - Google Patents

Abstract

PURPOSE:To offer a low-price inductance element having superior over-all magnetic characteristics and low magnetic permeability-temperature coefficient. CONSTITUTION:Firstly, an alloy consisting of silicon of 3-8%, alumiium of 2- 5%, nickel of 6% or less, iron as residual, and unavoidable impurities is melted in vacuum or in argon gas to form suitable shaped casting after casting. The casting is preserved for several hours at a temperature of 600-1,300 deg.C to contrive the uniform crystallization of the alloy. Next, forging is done and a suitable billet is made while supplying the alloy with viscosity. Next, the billet is pulverized to form a circular or flattening particles with a stamp mill or a suitable lump breaker. If necessary, the very fine magnetic powder of ferrite having high magnetic permeability of 10% or less is added to the particles and is mixed with the suitable amount of a binding agent having superior electrical insulation. Next, the easy magnetization direction is agreed with the magnetization direction at the time of using a dust core by applying an external magnetic field. Finally, the mixed substance is compressed and molded, and the powder and the binding agent are sufficiently contacted by heating for several hours.

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing a powder magnetic core.

Conventionally, a high permeability alloy consisting of 9.5% silicon, 5.5% aluminum, and the balance iron is known as Sendust.
Powder magnetic cores made from the shredded alloy are also known. The method for manufacturing this powder magnetic core involves casting the alloy, annealing it at high temperatures, pulverizing it into fine powder, applying an electrically insulating coating to it, mixing it with a binder, and pressing it. Although powder magnetic cores have excellent properties, their drawback is that their maximum magnetic permeability is 90, and even a similar powder magnetic core made of molybdenum 4-malloy has a magnetic permeability of only 130. Although a ferrite powder magnetic core has a magnetic permeability of about 1000, it has the disadvantage of a large permeability temperature coefficient.

SUMMARY OF THE INVENTION An object of the present invention is to provide an inductance element that has excellent overall magnetic properties, a small temperature coefficient of permeability, and is inexpensive.

As a result of numerous tests and studies by the present inventors, Si-Avl
-Ni-F@ system magnetic alloy is forged, rolled, and pulverized into acicular or flat particles, and if necessary, magnetic fine powder having a temperature coefficient of a sign different from the magnetic permeability temperature coefficient of the magnetic alloy, For example, ferrite powder may be added and this powder may be treated in an external magnetic field or by other means capable of longitudinally aligning the particles so that the direction of easy magnetization coincides with the direction of magnetization when used in the dust core. As a result, the magnetic permeability is 20
It has been discovered that a powder magnetic core with a small permeability/output temperature coefficient of 0 to 500 can be obtained.

That is, the manufacturing method of the powder magnetic core of the present invention includes 3 to 8 parts by weight of silicon,
A magnetic alloy consisting of 2 to 5 layers of aluminum, 6 layers or less of nickel, the balance iron and unavoidable impurities is cast, rolled by high temperature or room temperature processing, and the acicular particles are crushed into flat particles, and then A ferrite powder with a correspondingly high permeability is added, then mixed with a binder, placed in a magnetic field to align the powder particles in the direction of easy magnetization, compacted and sintered.

In the manufacturing method of the present invention, first, an alloy consisting of 3-8% silicon, 2-5% aluminum, 6% nickel or less, the balance iron and unavoidable impurities is melted in vacuum or in argon gas, and then cast. and cast into a suitable shape. This is 6
The alloy is maintained at a temperature of oOu to 1300°C for several hours to uniformly crystallize the alloy, and then forged at 1000 to 1200°C to create a suitable billet while imparting viscosity to the alloy. This is 7
The material is hot rolled at 00 to 1500°C in hydrogen or argon gas to prevent oxidation, and then heated to 500 to 700°C, quenched in oil to reduce hardness, and oxides on the surface are removed at room temperature. This is formed into a thin plate by cold rolls, and then finely pulverized into acicular or flat particles by a stamp mill or a suitable crusher. Such fine particles are selected and heated to a temperature of 300 to 800°C to oxidize or not oxidize the surface of the particles, and if necessary, ferrite poles with a high magnetic permeability of less than 10 are added to the particles. A fine magnetic powder is added and mixed with an excellent electrically insulating binder of "tin".Then, it is put into a suitably shaped pressing mold and pressed, and before or after this pressing molding, for example 400 100 at ~600℃
By applying an external magnetic field of 0 oersted 1, the direction of easy magnetization of the powder is made to match the direction of magnetization when the dust core is used.

Finally, this is compression molded and heated at a temperature of 500 to 800 DEG C. for several hours to fully adhere the powder and binder. The magnetic permeability of the thus obtained dust core is 200 to 500.
Moreover, since it uses a material that is a flat (flake) powder and has a specific electrical resistance ρ of 100 μΩ/cm 2 , it exhibits very excellent characteristics with little eddy current loss.

Claims (1)

[Claims] A magnetic alloy consisting of 6 to 8 weight percent silicon, 2 to 5 weight percent aluminum, 6 weight percent or less nickel, the balance iron and unavoidable impurities is cast and rolled by high temperature or room temperature processing,
Grind into needle-shaped or flat-shaped particles, optionally add ferrite powder with high magnetic permeability, then mix with binder,
A method for producing a powder magnetic core, which is characterized by placing powder particles in a magnetic field, easily aligning the powder particles in the direction of magnetization, compression molding, and sintering.