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Method for Precisely Preparing High Permeability Nanocrystalline Magnetic Core

by:Transmart     2022-12-24

A preparation method for processing and cutting a nanocrystalline magnetic core, especially a preparation method capable of improving the magnetic permeability of the magnetic core.

Nanocrystalline core processing

In recent years, amorphous magnetic cores are popular for their high saturation magnetic induction, low high-frequency loss rate and excellent frequency characteristics. In many fields, amorphous magnetic cores have begun to replace traditional inductive material cores, such as iron oxide and magnetic powder cores. At present, the preparation steps of amorphous magnetic cores include solidifying the amorphous alloy and then cutting. The actual production process still follows the traditional method of preparing iron cores to prepare amorphous and nanocrystalline magnetic cores. The magnetic permeability of the magnetic cores produced in this way is Very low, and the temperature performance is very poor, can not meet the requirements.

The traditional magnetic core curing process is that the iron core is vacuum impregnated for about 30 minutes and then sprayed with paint at room temperature. The paint spraying time is about 30 minutes, and then it is directly put into an oven and baked at about 130°C for 5 hours for curing. The disadvantage of this kind of process is that the ordinary varnish cannot completely remove the excess glue paint contained inside the iron core. Another fatal disadvantage is that the excess glue paint will be lost during the period when the iron core rises from normal temperature to the curing temperature (such as 130°C). It flows out from the inside of the iron core, resulting in the final surface of the iron core being dirty and lacquered, which affects the subsequent cutting accuracy.

In the traditional curing process, epoxy resin is often used as the binder of the magnetic core. Epoxy resin has the characteristics of good chemical stability, strong adhesion, and excellent electrical properties. However, the commonly used curing agent for epoxy resin is low-molecular-weight polyamide. The low-molecular-weight polyamide has a relatively high viscosity, poor fluidity and poor permeability during the impregnation process, and will affect amorphous, nano Crystalline strips produce a lot of stress, and because of the sensitivity of amorphous and nanocrystalline strips to stress, studies have shown that as the viscosity of the curing agent increases, the loss change rate of the amorphous iron core and nanocrystalline iron core increases. The rate of change of magnetic permeability increases. Therefore, using low-molecular polyamide as a curing agent, the stress generated during the curing process will reduce the magnetic properties of the cured iron core.

The traditional method of cutting the magnetic core is to use silicon steel sheets to cut, and the cutting surface of the magnetic core will produce air gaps and burrs, which will lead to low magnetic permeability and poor temperature characteristics of the magnetic core, which cannot meet the accuracy level and temperature of transformers, sensors and other devices. characteristics and miniaturization requirements.

Therefore, it is necessary to design a preparation process suitable for the nanocrystalline magnetic core, which must be a method that can effectively improve the magnetic permeability and tolerance of the nanocrystalline magnetic core.

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