Method for performing insulating treatment on metal magnetic powder and preparing metal magnetic powder

Abstract

The invention discloses a method for performing insulating treatment on metal magnetic powder and preparing metal magnetic powder. The method comprises the following steps: reacting phosphoric acid and boric acid on the surface of metal magnetic powder, generating and absorbing a layer of phosphate and borate on the surface of the metal magnetic powder to obtain required B and P diffusion sources; under a vacuum atmosphere, performing diffusion reaction, diffusing B and P elements on the surface of the metal magnetic powder to inner part of the metal, and forming a metal gap compound containing B or P below a metal magnetic powder phosphate and borate coating layer after penetrating B and P on the surface of the metal magnetic powder. The metal gap compound and the boric acid left outside the magnetic powder have low melting point, are changed to be liquid at a high temperature to achieve the effects of an inorganic binder. The method has the beneficial effects of improving the insulation of the metal magnetic powder surface, and improving the resistance of the metal magnetic powder particles and the contact resistance of the magnetic powder; inorganic binding coater is adopted to directly form, so that the cost is reduced, the magnetic core strength is improved, and the atmospheric pollution is avoided.

Description

technical field [0001] The invention relates to the technical field related to the manufacture of metal soft magnetic materials, in particular to a metal magnetic powder insulation treatment and a method for preparing a metal magnetic powder core. Background technique [0002] Metal soft magnetic is a material with high saturation magnetic induction, which can reduce the volume of the device, but the disadvantage is that its resistivity is low and it is not suitable for high-frequency applications. The metal magnetic powder core is to overcome the shortcomings of low resistivity of metal soft magnetic materials. Firstly, the metal soft magnetic material is prepared into powder, and then the resistivity is increased by powder insulation treatment, and then the required soft magnetic core is obtained by pressing and subsequent heat treatment. magnet. Because the particle size of metal magnetic powder is small, and the surface is covered with a layer of insulating material, wh...

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Problems solved by technology

[0003] There are many methods of metal magnetic powder insulation treatment. After the magnetic powder insulation treatment, the performance of the prepared magnetic core is also quite different.

Chinese patent CN101089108 has invented a kind of inorganic insulating adhesive for metal soft magnetic magnetic powder core and preparation method, and this inorganic insulating adhesive is made of SiO 2 、Al 2 o 3 , ZrO 2 , mica powder and water, this method is beneficial to improve the magnetic properties of the powder core, plays a certain positive role in improving the mechanical strength of the powder core, and solves the problem of powder core aging and performance degradation caused by heat generation during the use of the powder core , but there are also some shortcomings, because the SiO 2 、Al 2 o 3 , ZrO 2 , mica powder and water mixture, the bonding strength is not high, it is only attached to the surface of the magnetic powder by physical surface adsorption, and it is not firmly combined with the magnetic powder

During the mixing and molding process of magnetic powder, the inorganic substances on the surface are easy to fall off, resulting in uneven insulation coating, decreased resistivity, and increased eddy current loss of the magnetic core.

Therefore, the preparation method of this patent has defects such as uneven coating, and the magnetic powder insulation is easy to fall off.

Chinese patent CN103594219A adopts the method of phosphoric acid surface passivation to carry out insulation treatment on the surface of magnetic powder. The preparation process is simple and easy and improves the magnetic performance. However, the method of phosphoric acid surface passivation is used, and the phosphate generated on the surface is not resistant to high temperature, above 600 degrees. Decomposition will occur, the insulation performance of the magnetic powder will be reduced, and the loss of the magnetic core will be increased; on the other hand, the patent uses an organic binder, which will cause the problem of aging of the magnetic core