JPS6222402A - Amorphous magnetic alloy powder and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain amorphous magnetic alloy powder, on which surface coating films having high insulating properties are formed, at low cost by shaping copper oxide films on the surfaces of each particle. CONSTITUTION:An amorphous magnetic alloy generally uses at least one kind of iron, nickel and cobalt as a basic ingredient, employs at least one kinds of phosphorus, carbon, boron and silicon as a semimetal and used one kind or more of aluminum, titanium and rare earth elements and the like are required. It is preferable that a composition, a eutectic point thereof is close to a eutectic point between several two elements used, is employed. The amorphous alloy can be acquired as a filmy or powdered state through super- quenching from the state of melting through a known arbitrary method, and can be manufactured through various methods, such as an atomizing method, a twin roll method, etc. With amorphous magnetic alloy powder obtained, copper oxide films are formed on the surfaces of particles. The precipitation of metallic copper through electroless plating and subsequent oxidation treatment are used as a forming method for preferable copper oxide films.

Description

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

[Prior art and its problems]

Amorphous magnetic alloys have excellent properties such as high magnetic permeability and low coercive force, so they have recently been researched as magnetic cores in transformers, electric motors, yoke materials, and other inductances, and as materials for magnetic heads. Some parts have been put into practical use. These amorphous alloys have iron, nickel, and cobalt as basic components, and metalloid elements such as phosphorus, boron, and
Using silicon and carbon, adding titanium, aluminum, molybdenum, chromium, tungsten, zirconium, niobium, hafnium, etc. as necessary, mixing to have a composition near the eutectic point, and ultra-quenching from a high temperature molten state. That's what you get.

Generally, amorphous alloys are obtained as films, but in the case of films or fibers, which can also be obtained as thin fibers or powders, they are ground into powder. To manufacture a magnetic core from this, a binder such as glass or epoxy is used, and compression molding is performed by applying high pressure at a relatively high temperature. If the binder is polycrystalline, the magnetic permeability will decrease, so it is generally used in a small amount, but conversely, there are more opportunities for amorphous metal particles to come into contact with each other, which reduces the electrical resistance of the green compact and reduces eddy current loss. As a result, loss increases on the high frequency side and magnetic permeability also decreases. Furthermore, if the number of binder claws is small, the 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 Application Laid-open Nos. 59-179729 and 60-26603).
, to form such an oxide film, amorphous alloy powder is charged into an autoclave together with water and heated under high temperature and high pressure due to water vapor.
It is obtained by processing in an oxidizing atmosphere for several hours to several days to form a layer of Fe104, Co304, NIO, etc. on the surface of powder particles. It is reported that this improves the moldability of the powder and increases its magnetic permeability. When the main component of the amorphous alloy is iron, the oxide film is mainly made of F.304. However, as is well known, F.304 is a good conductor (as is Co304, and !'ilO is N
(is generally conductive because it tends to cause is+), it is not possible to make the resistance of the green compact sufficiently high, and it is insufficient for improving various characteristics on the high frequency side. Furthermore, the oxidation process requires equipment and a long time.

[Object of the Invention] An object of the present invention is to provide an amorphous magnetic alloy powder with a highly insulating surface film formed thereon and an inexpensive manufacturing method thereof.

[Summary of structure and effects of the invention]

The present invention relates to an amorphous magnetic alloy powder characterized in that an oxide coating is formed on the surface of each particle, the formation of a copper coating using an electroless plating method, and the conversion to a copper oxide coating by oxidation. This is a 1:L method characterized by its characteristics.

The powder of the present invention has a highly insulating acid copper coating on its surface, which stabilizes the properties of the amorphous alloy! rR in the air
It is possible to prevent changes in characteristics over time due to oxidation caused by elements, and it is possible to provide a highly reliable inductor. In addition, the copper oxide coating can be formed using a simple process of forming a copper coating using the electroless method and then oxidizing it, so it does not require the long processing time required in conventional methods. . In addition, this powder has good moldability, so
Inorganic or organic binders may not be used, or may be used only in small amounts. Therefore, since the magnetic core can be a high-density magnetic core, it has a high magnetic flux density, and the frequency characteristics are improved due to its high insulation properties.

[Detailed description of the invention]

The amorphous magnetic alloy used in the present invention may have any known composition. As already mentioned, generally at least one of iron, nickel, and cobalt is used as a basic component,
At least one of phosphorus, carbon, boron, and silicon is used as the semimetal, and if necessary, aluminum, titanium, chromium, manganese, vanadium, zirconium, molybdenum, copper, niobium, tungsten, thallium, rhenium, platinum, gold, One or more of silver, palladium, and rare earth elements are used. A preferred composition is one near the eutectic point between the two elements used. This amorphous alloy can be obtained in the form of a film or powder by ultra-quenching from a molten state using any known method. For example, it can be manufactured by various methods such as an atomizing method, a thermal spraying method, a single roll method, and a twin 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 copper oxide on the particle surface according to the present invention. A preferred method for forming a copper oxide coating is the deposition of metal steel by electroless plating followed by an oxidation treatment. Copper easily oxidizes in a short time under heated conditions. For example, copper sulfate 10-30 Il/l, hydrogen carbonate +3 um or sodium carbonate 5-sol/l
, potassium sodium tartrate 20-1001/l, sodium hydroxide S5-559/l, formalin solution 20-2
A powdered amorphous magnetic alloy is immersed in an electroless plating solution consisting of 00 Rt/l and stirred appropriately. When this is washed with water and dried in a rotary kiln at a temperature of about 150 to 200°C, the copper on the particle surface is oxidized and converted into a copper oxide film with a thickness of about 300 to 1 μm.

The surface of the obtained powder is protected by oxidized steel and has high insulation properties. Therefore, it can be used as various inductors, electric motors, and yoke materials. In other words, amorphous magnetic powder with surface oxidized copper is The powder is compacted into a 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 5vt%.Alternatively, a small amount of lubricant may be added to increase compaction properties; in this case, It is not necessary to use a binder.

The magnetic powder of the present invention has improved stability, electrical resistance, and moldability because of the copper oxide coating on the surface. Moreover, the magnetic permeability of the magnetic core can be increased for this reason, and the high frequency characteristics are further improved. Furthermore, the manufacturing method is simpler and faster than conventional methods, resulting in lower costs.

Example A molten alloy having a composition of 2078%-819%-B13% in terms of atomic ratio (crystallization temperature 510°C) was super-quenched by spraying onto a cold roll using a single roll method, and a thickness of 2
A thin plate of an amorphous magnetic alloy with a width of 5 μm and a width of 1 Q Q mm was manufactured. Next, it was subjected to an embrittlement treatment at 4SO DEG C. for 1 hour in an inert gas flow, and then ground in a grinder to obtain a powder of 80 to 150 meshes.

Sulfuric acid steel 151/l, sodium hydrogen carbonate 1011/l
.

The above powder was immersed and stirred in an electroless methane stone containing 501/11 sodium potassium tartrate, 201/l sodium hydroxide, 100/l 37% formalin solution, pH 115 and temperature 24°C to obtain a particle surface IP: copper. The precipitate became clear. After washing with water, the powder was heated to 150° C. in a rotating barrel drying and heat treatment device to obtain a dry powder. During drying, the magnetic powder turned into a black powder due to the oxidation of the copper by oxygen in the air.

Approximately 2vt% of fluororesin powder was added as a lubricant to the powder thus obtained, and the mixture was charged into a mold and heated at 460°C and 800°C.
It was compacted for 3 minutes under MPa conditions to have an outer diameter of 25 mrn.
, a toroidal magnetic core with an inner diameter of 10 mm and a thickness of 3 ms was obtained. A conductive wire was attached to this in the form of a coil, and the magnetic properties were measured. Figure 1 shows the results.

White porcelain 1 is the circumference of μ (magnetic permeability) of the magnetic core of the present invention! Shows i-number dependence. Further, curve 2 shows the case where an Fe104 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. It is also found that the magnetic powder of the present invention has good moldability. In addition, the entire process can be completed within one hour to form an oxidized substance on the surface, which is much more economical than the method of oxidizing the amorphous alloy powder itself.

[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.
) Figure 1

Claims (1)

[Claims] 1. Amorphous magnetic alloy powder with a copper oxide coating formed on the particle surface. 2. A method for producing an amorphous magnetic alloy powder, which comprises forming a copper layer on the particle surface of the amorphous magnetic alloy powder by electroless plating, and then subjecting it to oxidation treatment.