Sendust Ring Inductors Powder Core

Sendust Core, which is made from 6%Al,9%Si and 85%Fe,is mainly used to replace iron powder core because its core loss is 80% less than powdered iron, so it can be applied with the frequency above 8kHz.Sendust core has a saturation flux density of 1.05T and permeability from 14 to 125.The nearly zero magnetostriction alloy makes sendust ideal for eliminating audible frequency noise. Sendust core also has better DC bias characteristics and the best cost performance. It is mainly applied in AC inductor, output inductor ,in-line filter, power factor correction inductor etc. It can also be used as transformer core in some circumstances.

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In 1932,Masumoto and Yamamoto at Tohoku Imperial University developed new Fe–Si–Al alloys. The alloys were discovered in Sendai and designed for magnetic dust core, so they named the alloys “Sendust” (Masumoto and Yamamoto, 1937). They found that the alloys with 6–11 wt% Si and 4–8 wt% Al show excellent soft magnetic properties. Among them, the Fe–9.62Si–5.38Al shows the largest initial permeability of 35100 and a low coercivity of 1.75 A/m; the Fe–9.66Si–6.21Al shows the largest maximum permeability of 162,000 and a low coercivity of 1.59 A/m. The good soft magnetic properties are due to that the composition meets the ideal condition of K1=0 and λs=0 simultaneously. The alloys show a high saturation flux density of about 1.0 T. Due to its chemical composition and crystallographic structure, Sendust alloys also show very high resistivity, low hysteresis loss and good temperature stability.


Its main characteristics are as follows:

 1. It has high saturation flux density. The saturated magnetic flux density of iron powder core can reach 1500mT, the high flux magnetic particle core can reach 1300mT, the saturated magnetic flux density of iron silicon aluminum magnetic particle core can reach 1000mT, and even the MPP magnetic particle core with the lowest saturated magnetic flux density among the four series of metal soft magnetic particle cores can reach 800mT. This property retains the advantages of metal soft magnetic, which is far inferior to ferrite soft magnetic materials.

 2. It has high effective permeability. Such as MPP magnetic particle core, at 10KHz, μe value can be more than 500. Iron powder core with the lowest effective permeability – 26 material, at 10KHz, μevalue can also reach about 75. However, we used super permalloy soft magnetic rolling to the thickness of 0.01 mm. After the strip is divided and treated by electrophoresis coating, the initial permeability is as high as 200000, and the maximum permeability is higher than 800000. But measured at 10KHz ,μe value is only about 60, far less than that of metal soft magnetic particle core.

 3. Low loss, good frequency stability and wide frequency range. The metal soft magnetic powder cores of various materials and different permeability can be used in a very wide frequency band from tens of Hertz to up to 30 MHz. This characteristic is far inferior to metal soft magnetic field and amorphous microcrystalline soft magnetic field.

 4. Due to the above three advantages, the metal soft magnetic powder core has good AC/DC superposition stability. This is of great significance when many AC and DC fields exist at the same time. This is also where it is superior to other soft magnetic materials.

 5. It has good magnetic stability. This feature is very important for the use and quality assurance of products. If the stability of magnetic properties cannot be guaranteed, very precise instruments will become unusable and cause losses. Metal soft magnetic powder core is superior to other materials in frequency stability and temperature stability.

 6. It also has a very important unique and excellent characteristic that any other soft magnetic materials do not have, that is, it has good controllability of performance. That is to say, in the production process of various kinds of metal soft magnetic powder cores, people can control and change their production process and technical conditions to produce various metal soft magnetic powder cores with unique performance, so as to meet various requirements under various use conditions to the maximum extent.


Application field:

1. PFC chokes for large current.

2. Reactor for electric vehicles/air condition.

3. Power inductor for fuel cell vehicles.

4. In line noise filters.

5. EMI filters.

6. Boost inductors.

7. Switching regulator inductors.


1. High saturation magnetic pass density, so it can be in the larger magnetization off not easily saturated.

2. Has the high permeability.

3. Magnetic can have good stability, low temperature resistance, high current, low noise).


Sendust core are formed by adding a certain amount of glass forming agent to the molten metal, and rapidly quenching and casting using a narrow ceramic nozzle under high temperature melting conditions. Amorphous alloys have the similar characteristics of glass structure, which not only make them have excellent mechanical properties, physical properties and chemical properties, but more importantly, the new technology of producing amorphous alloys using this rapid quenching method is less than the cold-rolled silicon steel sheet process. 6 to 8 processes can save energy consumption by 60% to 80%, which is an energy-saving, time-saving and efficient metallurgical method. Moreover, the amorphous alloy has low coercivity and high magnetic permeability, and its core loss is significantly lower than that of oriented cold-rolled silicon steel sheet, and its no-load loss can be reduced by about 75%. Therefore, the use of amorphous alloys instead of silicon steel sheets to manufacture transformer cores is one of the main means to save energy and reduce consumption in today’s power grid equipment.

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