Preparation Of FeSiCr Soft Magnetic Powder By Water Atomization

One-piece inductors have the characteristics of small size,low loss,high current resistance,high stability,and are widely used in mobile communications,electronic products,automotive electronics and other fields.At present,the main material for forming the integrated molded inductor is FeSiCr soft magnetic alloy powder,which has high magnetic permeability,low magnetic loss in medium and high frequency,and the like.In this paper,FeSiCr soft magnetic alloy powders were prepared by water atomization,and the effects of melt temperature,atomization water pressure and atomization water flow rate on the physical properties of FeSiCr soft magnetic alloy powders were studied,and the optimal FeSiCr alloy powders were obtained.Atomization process.Analyze and study the oxidation behavior of alloy powder during atomization,provide theoretical support for reducing the oxygen content of powder,and characterize and study the magnetic properties of FeSiCr alloy powder.The particle size,morphology,oxygen content,bulk density,and fluidity of FeSiCr alloy powders were tested and analyzed using laser particle size analyzer,scanning electron microscope,oxygen-nitrogen analyzer,and Hall flowmeter.The results show that with the increase of atomization pressure and melt temperature,the particle size of the powder gradually decreases,the flow rate of atomized water is reduced,the prepared powder morphology is more regular,and the powder particle size and bulk density are improved.The best atomization process parameters were obtained by experiments.The prepared FeSiCr soft magnetic alloy powder has low oxygen content,small average particle size and more regular morphology.The composition,morphology and thickness of surface oxides of water-atomized FeSiCr soft magnetic alloy powders were studied.Using Auger electron spectroscopy surface analysis technology,combined with high resolution scanning electron microscopy and EDS elemental analysis,the oxides formed on the powder surface were studied.The conclusions are as follows:The surface of water-atomized FeSiCr soft magnetic alloy powder is mainly composed of Fe-oxide and Cr-and Si-rich oxides.Its morphology is characterized by inhomogeneous oxide layer and fine-grained nano-particle characteristics.Combined with AES and SEM analysis,substantially all of the Cr in the FeSiCr alloy powder forms oxides on the surface of the particles,and only a part of the Si is selectively oxidized on the surface.A mixture of chromium nitride and chromium oxide may form on the surface of the powder particles.Within the etching depth of 0 to 18.6 nm,the Fe oxide content decreases,and the Cr content first increases and then decreases,indicating that Fe-Cr spinel exists in the powder.The average thickness of the Fe-oxide layer is about 22 nm.The FeSiCr soft magnetic alloy powder prepared by water atomization has excellent magnetic properties.The influence of different powder particle sizes on magnetic properties was studied in this paper.The results show that with the decrease of magnetic particle size,the effective magnetic permeability of the magnetic powder core decreases,and the eddy current loss of the powder increases with the increase of the particle size of the powder.The larger the particle size of the powder,the smaller the Q value of the powder.With the increase of molding pressure and heat treatment temperature,the effective magnetic permeability of powder increases,and the loss of magnetic powder core decreases.However,the molding pressure and temperature must not be too large.Otherwise,the powder insulation layer will be destroyed,which will increase the loss and deteriorate the performance of the magnetic powder core.