JPS6222410A - Amorphous magnetic alloy powder and dust core using said powder - Google Patents

Abstract

PURPOSE:To improve stability, high electric resistance and moldability, t0 enhance even the permeability of a magnetic core and to ameliorate high-frequency characteristics by forming phosphate films on the surfaces of each particle. CONSTITUTION:With an amorphous magnetic alloy used, at lest one kind of nickel and cobalt is employed as a basic ingredient, at least one kind of carbon, boron and silicon is used as a semimetal, and at lest one kind of element of aluminum, titanium, chromium, rare earth elements, etc. is employed s required. The amorphous alloy can be obtained as a filmy or powdered shape through ultra-quenching from the state of melting. A phosphate film is shaped in such a manner that amorphous magnetic alloy powder is dipped in a phosphate solution and treated in a short time at a comparatively high temperature. Zinc phosphate, manganese phosphate, iron phosphate, calcium phosphate, cadmium phosphate, etc. can be used as phosphate employed. Surface-treated amorphous magnetic alloy powder is molded to dust core to a predetermined magnetic core shape.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an amorphous magnetic alloy powder and a dust core using the same.

[Prior art and its problems]

Amorphous magnetic alloys have excellent soft magnetic properties such as high magnetic permeability and low coercive force, so they have recently been researched into transformers, electric motors, rice inductors, and magnetic heads, and some have been put into practical use. . These amorphous alloys have iron, nickel, and cobalt as basic metal components, phosphorus, boron, silicon, and carbon as metalloid elements, and, if necessary, other elements such as titanium, aluminum, zirconium, molybdenum, It is obtained by adding tantalum, Cr%W, niobium, hafnium, etc., mixing to have a composition near the eutectic point, and ultra-quenching from a high temperature molten state.

Amorphous alloys are obtained as films, fibers, or powders, and in the case of films, they are ground into powders. To manufacture magnetic cores from these materials, a binder such as glass or epoxy resin is used and compression molding is performed at elevated temperatures and high pressures. A large amount of binder lowers the electromagnetic coefficient, so a small amount is generally used, but on the other hand, there are more opportunities for the amorphous metal particles to come into contact with each other, which reduces the electrical resistance of the green compact, and eddy currents reduce the high frequency side. In this case, power loss increases and magnetic permeability also decreases. Moreover, if the amount of binder is small, mechanical strength will be reduced.

In order to overcome the above-mentioned defects, it has been proposed to oxidize the surface of an amorphous alloy to form an oxide film (Japanese Patent Laid-Open Nos. 59-179729 and 60-26603).

Such an oxide film is formed by charging the amorphous alloy powder with water into an autoclave and treating it in an oxidizing atmosphere at high temperature and high pressure with water vapor for several hours to several days to coat the surface of the powder particles with Fe, 04, and Co. , 04, NiO, etc. It is reported that this improves the moldability of the powder and increases its magnetic permeability. In the case of an amorphous magnetic alloy whose main component is iron, the oxide film is mainly Fe sO4. However, as is well known, since Feρ4 is a good conductor (Co and 04 are also good conductors, and NiO tends to generate Ni5+ and is generally conductive), it is insufficient for improving the wave characteristics on the high frequency side. Furthermore, the oxidation process requires equipment and a long time.

[Purpose of the invention]

Therefore, an object of the present invention is to provide an amorphous magnetic alloy powder with a highly insulating surface coating and an amorphous magnetic alloy dust core with good characteristics.

[Summary of structure and effects of the invention]

The present invention provides an amorphous magnetic alloy powder characterized in that a phosphate coating is formed on the surface of each particle, and a magnetic core made by compacting the same.

Since the powder of the present invention has a highly insulating oxide film on its surface, it can stabilize the properties of the amorphous magnetic alloy and prevent changes in properties over time due to oxidation caused by oxygen in the air, making it reliable. It can be used in a wide range of applications as a highly durable magnetic core.

Moreover, the phosphate coating can be formed in a short time using a simple process.

In addition, this powder has good moldability, so a small amount of inorganic/organic binder may be used (depending on the application, it may not be necessary to use it), and it can be made into a high-density magnetic core, so it has high magnetic flux density and high insulation properties. Therefore, the frequency characteristics are improved.

[Detailed description of the invention]

The amorphous magnetic alloy used in the present invention may have any known composition. As already mentioned, at least one of K, iron, nickel, and cobalt is used as a basic component, and at least one of phosphorus, carbon, boron, and silicon is used as a semimetal, and if necessary, aluminum, titanium, chromium, and manganese are used. , molybdenum, tantalum, vanadium, zirconium, copper, niobium, tungsten, thallium, rhenium, platinum, gold, silver, palladium, pdium, rubidium, hafnium, and a rare earth element. A preferred composition is one near the eutectic point between each of the two elements used. This amorphous alloy can be obtained in the form of a film or powder by ultra-quenching the molten state by any known method. For example, it can be manufactured by various methods such as an atomizing method, a thermal spraying method, a twin roll method, and a single roll method. When an amorphous alloy is obtained in the form of a film, it can be pulverized into powder after hydrogen embrittlement or other embrittlement treatment.

The obtained amorphous magnetic alloy powder is coated with phosphate on the particle surface according to the present invention. To form a phosphate film, amorphous magnetic alloy powder is immersed in a phosphate solution and treated at a relatively high temperature for a short period of time.

As the phosphate that can be used, zinc phosphate, manganese phosphate, iron phosphate, cadmium phosphate, calcium phosphate, etc. can be used. For example, in the case of zinc phosphate, it is heated to 60 to 100°C in an aqueous solution with a concentration of 100% for several minutes.
It is enough to process for about 30 minutes. Due to this K, phosphate adheres to the surface of the amorphous magnetic alloy particles in the form of a film.

The amorphous magnetic alloy powder that has undergone the surface treatment is then compacted into a predetermined magnetic core shape. At this time, a small amount of glass or synthetic resin may be added as a binder, for example, up to about 5 wtX. Alternatively, a small amount of lubricant can be added to increase the compactability, in which case no binder is needed.

The magnetic powder of the present invention has improved stability, high electrical resistance, and moldability due to the phosphate coating on the surface. This also increases the magnetic permeability of the magnetic core, and further improves high frequency characteristics.

The present invention will be explained in detail below.

Examples Expressed in atomic ratio: Fe 78%-8i 9%-815%
A molten alloy with a composition of did. Next, it was subjected to an embrittlement treatment at 430° C. for 1 hour in an inert gas stream, and then pulverized using a pulverizer to obtain a powder of 80 to 150 meshes.

Prepare a 3% zinc phosphate aqueous solution, add amorphous alloy powder to it, and treat at a temperature of 95 to 100°C for about 10 minutes.
A coating of zinc phosphate was formed on the surface of the powder particles. Thereafter, the alloy powder was dried in hot air to obtain the desired magnetic powder.

Boron nitride was added to the powder thus obtained as a lubricant.
Add wtX, charge into a mold, and heat at 460°C.

The powder was compacted for 3 minutes under the condition of 800 MPa and the outer diameter was 25 mm.
m+11. A toroidal magnetic core with an inner diameter of 10 m+11 and a thickness of 5 m was obtained. A conducting wire was wound around this in a coil shape, and the magnetic properties were measured. Figure 1 shows the results. Curve 1 shows the frequency dependence of μ (magnetic permeability) of the magnetic core of the present invention. Also curve 2
shows the case where a Fe, 04 film is provided on the particle surface of the same amorphous alloy powder. This clearly shows that the magnetic alloy powder of the present invention does not change its magnetic permeability up to high frequencies. In addition, as mentioned above, the moldability is also good.

[Brief explanation of drawings]

FIG. 1 is a graph showing the μ-frequency relationship between the magnetic powder of the present invention and the conventional magnetic powder. −・. Name of agent: Motohiro Kurauchi -11 Yu, -Ding

Claims (1)

[Claims] 1. Amorphous magnetic alloy powder with a phosphate coating formed on the particle surface. 2. The amorphous magnetic alloy powder according to item 1 above, wherein the phosphate coating is selected from at least one of zinc phosphate, manganese phosphate, cadmium phosphate, calcium phosphate, and iron phosphate. 3. A magnetic core made by compacting an amorphous magnetic alloy powder with a phosphate coating formed on the particle surface. 4. The magnetic core according to item 3 above, wherein the phosphate coating is selected from at least one of zinc phosphate, manganese phosphate, cadmium phosphate, calcium phosphate, and iron phosphate.