Because the exist of distributing air spaces, characteristics of low
permeability and constant magnetic permeability, the metal magnetic
particles have been widely used in the field of power electronics and
electronic information. With the development of the electronics
industry, the requirements for miniaturization of electronic products
also will be improved. So does the performance of metal magnetic
particles which means that the new magnetic particles must have a high
saturation magnetic flux density, low-high frequency loss and a good
performance stability (including temperature stability, the stability of
the different DC magnetic bias field permeability and permeability
stability under different frequency). While in the use process, it
produces low noise with low prices. Iron silicon boron powder alloy is a
common iron-based amorphous alloy with high resistance and high
saturation flux density with extremely low iron loss and low-cost
advantages. The strip is easy to become brittle after annealing. It is
an ideal material for magnetic particles preparation.
In the powder metallurgy process, the most important point for study
amorphous material mechanical crushes performance is on the magnetic
properties of new powder cores with conventional powder cores (including
metal powder core temperature stability, the effective permeability
versus frequency, DC superimposed field changes and the Q value at high
frequencies, loss, etc.) of the difference. After pretreatment,
iron-based amorphous ribbons prepared using mechanical milling legal
system as amorphous powder, and at the same time be corrected airflow
broken powder morphology after sieving and particle size ratio to obtain
powder.
Aamorphous powder cores process is follows: powder passivation,
insulation coating, molding, and curing. The metal powder in the
phosphating solution passivation insulating material and the adhesive
coated handle, and then joined to the powder made of ring samples in the
four-post hydraulic press with pressure cold pressing. Finally the
curing in air is needed.
Respectively, the powder morphology of the composite crushing prepared
through ball milling and ball milling airflow. Strip directly ball
crushing, powder flaky, there are a large number of sharp corners, large
particles of the powder, the powder and class of a long strip of
triangles powder and small particles, compared with class square.
Relatively smooth powder prepared by milling airflow composite broken
grain boundaries, reduce the powder of long and sharp phenomenon, the
majority of powder close to the wafer-shaped. This strip broke he
preparation of powder characteristics. Strip mechanical crushing milling
rely mainly on the strip to break derived, which determines its sharp
corners too much powder, and this topography is not conducive to the
insulating coating of powder. Experiment that airflow broken law may be
amended to the powder morphology, is one of effective ways to reduce the
cusp morphology of the metal powder.
DC superposition is an important parameter to measure the dynamic
characteristics of the nickel powder cores. In some circuits,
alternating magnetic field and dc magnetic field, while the role of
powder cores, powder cores in this condition not only to have good
electrical and magnetic properties, but also has good DC superposition
characteristic, that is superimposed on a DC bias source the effective
permeability of powder cores attenuation changes as small as possible.
When DC superimposed magnetic field value 100Oe, the effective
permeability of the amorphous powder core attenuation changes in value
of 34. It is suitable for bigger current inductance device.
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