Sendust/ferrite composite magnetic powder and preparation method of magnetic powder core adopting same

Abstract

The invention relates to the field of material preparation, in particular to sendust / ferrite composite magnetic powder and a preparation method of a magnetic powder core adopting the same. The preparation method comprises the following steps: firstly, flat sendust magnetic powder is prepared, then, the sendust magnetic powder is put in a Fe-Zn-Mn mixed nitrate solution, a ferrite coating is synthesized in situ on the surface of the flat sendust magnetic powder through a hydrothermal reaction, the ferrite coating is washed, dried and mixed with a binder and a lubricant, the magnetic powder core is prepared from the sendust / ferrite composite magnetic powder through cold pressing, and then stress relief annealing is performed. The sendust / ferrite composite magnetic powder and magnetic powder core have high magnetic conductivity and low high-frequency loss, and can be applied to telecommunications and radar as well as fields of microwave absorption and electromagnetic shielding.

Description

technical field [0001] The invention belongs to the field of material preparation, and in particular relates to a method for preparing sendust / ferrite composite magnetic powder and its magnetic powder core. Background technique [0002] Sendust soft magnetic alloy, also known as Sendust alloy, has a chemical composition of 5.4wt.% Al, 9.6wt.% Si, and the rest is Fe (85wt.%). Sensil is very brittle and is easily broken into powder. It is generally prepared as a magnetic powder core for use. [0003] Compared with iron-silicon cores and iron powder cores, sendust magnetic powder cores have lower high-frequency loss, and have higher saturation magnetic induction and magnetic permeability, and are inexpensive, which is conducive to miniaturization. In addition, the magnetostriction coefficient λ of sendust s Close to zero, it is beneficial to eliminate the auditory frequency noise generated when the filter inductor is working. Due to the characteristics of low loss, low cost,...

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Problems solved by technology

[0005] Chinese patent CN201210443610.X discloses a preparation process of a high magnetic flux density and low core loss sendust magnetic powder core. The target is obtained through steps such as powder selection, pretreatment, passivation treatment, insulation coating treatment, compression molding, and heat treatment. The prepared product has high magnetic permeability and low core loss, but the steps are relatively complicated

This kind of mechanical mixing is difficult to ensure the continuity of the ferrite insulating layer, and it is also difficult to completely block the electrical contact between the soft magnetic alloy particles.

[0007] Chinese patent CN103426580.A discloses a composite magnetic powder core and its preparation method. Ferrite particles are prepared in situ on the surface of soft magnetic alloy powder by hydrothermal method. Although the continuity of the ferrite insulating layer is improved, the method Only the soft magnetic alloy is passivated, not flattened, which is not conducive to reducing the high-frequency loss of the magnetic powder core and improving the magnetic permeability.

[0008] In summary, the insulation coating process used in the preparation methods of sendust magnetic powder cores commonly used at home and abroad at present, the non-magnetic insulating layer used dilutes the magnetism, resulting in low magnetic permeability, unstable insulating layer (pyrolysis) and low strength (magnetic powder The cladding layer is easily crushed during the core compression molding process) resulting in high frequency loss

In addition, the currently commonly used sendust magnetic powder is not flat enough, which is not conducive to further improving the magnetic permeability and reducing high-frequency loss