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One, introduction

Metal powder soft magnetic composite materials (commonly known as magnetic core) is mainly composed of metal magnetic powder as matrix materials, the dielectric particles surface coating, and mixed with proper amount of organic or inorganic binder in powder, the powder metallurgy process will powder press molded into a certain shape, and the treatment of soft magnetic material or products through the heat.

Because the soft magnetic powder core is made of ferromagnetic particles and insulating medium suppression and become, because of ferromagnetic particles is small (high frequency use of particles is 0.5 ～ 5 μ m), and the insulating film or the insulating material is separated, non-magnetic so it can isolate the eddy current, applicable for high frequency, on the other on one hand because the gap effect between particles and lead to materials with low permeability and constant magnetic properties, but also because the fine powder particle size, basically does not produce the "skin effect", so the permeability variation with frequency is stable

So the metal powder core is a kind of soft magnetic material is currently the most comprehensive performance. It retains some excellent characteristics of soft magnetic metal and soft magnetic ferrite, and at the same time, maximum overcome some of their drawbacks. For a variety of electronic products to achieve the development direction of high precision, high sensitivity and large capacity and miniaturization is very important.

In some developed countries such as the United States, in the last century 50's has carried out a large number of research and development work has made gratifying achievements and formed a series of products. Such as iron powder core series (iron cores), Po Mo powder core series (MPP), high magnetic powder core series (high flux) and FeSiAl magnetic powder core series (sendust), and in recent years the development of amorphous and nanocrystalline magnetic powder core products such as quickly.

Magnetic metal powder core special can make it with other materials in many applications the incomparable advantage, since this kind of material has become an important part of soft magnetic materials. Metal magnetic powder core production has a long history, but the real industrialization began in twentieth Century 80 years, with the rapid development of inverter technology and extensive application, along with the EMC requirements, metal powder core has been widely applied. In order to realize the high frequency, inductance device of high 寬恒 magnetic, high quality factor, so the magnetic device to miniaturization, intelligent, highly integrated and ultra fast transmission direction, magnetic metal powder core unique can use in special occasions, more than any other material advantages, it for promoting the development of various fields of Science and technology and promote social progress has played a very important role.

Since twenty-first Century, the people of the inverter in high frequency, high power density, small size and anti electromagnetic interference (EMC) of the increasingly high demand. FeSiAl magnetic powder core is a new type of composite electronic material, its price is the highest of all soft magnetic materials, development in the world is growing more than 40% a year in industry speed, it more than any other soft magnetic material. So the FeSiAl magnetic powder core is rapidly rising!

Classification and characteristics of point two, the metal soft magnetic material

Magnetoelectric properties of soft magnetic powder core depends on powder particle material permeability, powder particle size, shape and the filling coefficient, dielectric content, molding pressure and heat treatment process. Magnetic powder core has the most commonly used iron heart, Po Mo alloy powder and Fe Si Al heart heart 3. Following their characteristics:

1, iron powder core:

Iron core used are the use of pure iron powder (ultrafine carbonyl iron powder made of high-end products), the saturation magnetization value of around 1.4T, permeability ranging from 22 to 100, the initial permeability μ I changes with frequency stability, superimposed DC current performance is good, but the loss of high frequency. In the soft magnetic metal in the lowest price. Is the manufacture of differential mode filter, passive PFC inductance and power choke coil and the cheap and practical material

2 Po Mo alloy powder core

Po Mo alloy powder core is divided into Mo permalloy powder core (MPP) and high magnetic flux powder core (High Flux):

MPP is composed of Fe-81%Ni-2%Mo, the main features are: the saturation magnetization value of around 0.75T; permeability range, from 14 to 550; has the lowest loss in the magnetic heart, temperature stability is excellent, the magnetostrictive coefficient is close to 0, work in different frequency without noise generation. Mainly used for military engineering, space equipment, outdoor equipment etc.. The most expensive in the powder core material.

High quality factor filter, induction of MPP is mainly used in the 300kHz following the load coil, resonant circuit, usually used for high requirements for temperature stability of LC circuit, the output inductor, power factor compensation circuit, AC circuit, etc..

High flux powder core (HF) is composed of Fe50%-50%Ni, the price is lower than MPP, the main features are: the saturation magnetization value of around 1.5T; permeability ranging from 14 to 160; with the magnetic induction intensity was highest in the magnetic heart, DC bias the highest ability; core size small.

HF is mainly used in line filter, inductance and output inductance and power factor correction circuit, commonly used in the DC circuit, also used more in the high DC voltage, DC high and low alternating current.

3 sendust core (SENDUST):

Sendust core is composed of Fe-Si9%-Al5% alloy, the material is iron the heart of the upgrading of products, iron powder core loss than low 80%, can be used in the 10-50kHz frequency, saturation magnetic induction at around 1.05T, permeability of 26 ~ 125, the magnetostrictive coefficient is close to 0, no noise at different frequencies, there is higher DC bias power than MPP, with very high price.

Sendust core is mainly applied to the AC inductors, the output inductor, line filters, power factor correction circuit, sometimes instead of air gap ferrite transformer core used for. Although partial magnetic slightly worse than the HF material loss slightly worse than the MPP material, but because of the low price makes the iron silicon aluminum materials become a manufacturing power choke cost-effective material. In the civilian market, occupy almost the metal magnetic powder core choke for more than 80% market share. So in recent years the development of sendust core technology very quickly.