Preparation Process And Properties Of FeSiB Magnetic Powder Cores

The magnetic powder cores is a kind of composite soft magnetic material,which is prepared by powder metallurgy process.The magnetic powder cores has a good comprehensive performance,and it not only combines the advantages of metal soft magnetic materials and ferrite soft magnetic materials,but also can overcomes the lack of both.With the rapid development of technology,electronic devices are developing toward miniaturization,large capacity,high precision,and high sensitivity.Therefore,magnetic powder cores are required to have excellent properties such as high saturation magnetic induction,high magnetic permeability,and low loss.FeSiB amorphous magnetic powder cores has high saturation magnetic induction,low loss,good DC bias performance and good corrosion resistance,and it has broad application prospects.The magnetic properties of amorphous magnetic powder cores prepared with different particle sizes of FeSiB are different.When the magnetic particle size is small,the magnetic powder cores has low magnetic loss,but the magnetic permeability is also low.When the magnetic particle size is large,the magnetic powder cores has a high magnetic permeability,but the magnetic loss is also high.In order to solve this problem,this paper researches on the advantages and disadvantages of magnetic powder cores prepared with different sizes of FeSiB magnetic powders.The 600-mesh FeSiB amorphous magnetic cores has low magnetic loss and also low magnetic permeability.The purpose of this paper is to improve magnetic permeability by adding iron powder to prepare FeSiB/Fe composite magnetic powder cores.The effect of iron powder content,phosphating treatment,phosphating solution content,pressing pressure and heat treatment on the magnetic properties of FeSiB/Fe composite magnetic cores has been studied.The addition of iron powder can effectively increase the magnetic permeability and saturation magnetization of FeSiB magnetic powder cores,but the core loss also increases.The core loss can be reduced while ensuring high magnetic permeability by phosphating the iron powder,especially when FeSiB/Fe composite magnetic cores with Fe content of 20 wt.%.Under 50 mT,100kHz test condition,the FeSiB magnetic cores has core loss of 182.1W/kg,and the core loss of the composite magnetic cores after phosphating is 141.3W/kg,a relative decrease of 22.5%,and the magnetic permeability does not decrease substantially.Based on the above experiments,the preparation process is optimized.Phosphating solution content,pressing pressure and heat treatment temperature have a great influence on the properties of the composite magnetic cores.When the addition amount of iron powder is 20 wt.%,the concentration of phosphating solution is 4wt.%,the pressing pressure is 1200 MPa and the annealing temperature is 450℃,the composite magnetic cores can be prepared by the optimum process.The magnetic permeability is 42.3,and the core loss is 141.3W/kg.The 300-mesh FeSiB amorphous magnetic cores has high magnetic permeability and also high core loss.In order to reduce the magnetic core loss,the first method is to prepare the FeSiB/Ferrite composite magnetic powder core by adding ferrite powder.The effect of ferrite particle size and content on the performance of FeSiB/ferrite composite magnetic cores has been studied.The addition of ferrite can effectively reduce the magnetic loss of the magnetic powder cores.Ferrite with different particle sizes has a great influence on the properties of composite magnetic powder cores.The composite magnetic powder cores containing 500-mesh ferrite powder has better magnetic properties than the composite magnetic powder cores containing 300-mesh and 700-mesh ferrite powder.Under 50 mT,100kHz test condition,the magnetic permeability of composite magnetic powder containing 10 wt.% ferrite is 41.0,and the core loss is 115W/kg.Compared with FeSiB magnetic powder cores,the core loss is reduced by 24.8%,while the magnetic permeability is reduced.The ferrite content has a great influence on the properties of the composite magnetic powder cores.The magnetic permeability of the FeSi B magnetic powder cores is 43.3,and the magnetic permeability of the composite magnetic cores containing 4wt.% ferrite is up to 42.4 basically no reduction.As the ferrite content continues to increase,the magnetic permeability of the composite magnetic cores decreases.As the content of ferrite increases,the core loss of the composite magnetic cores decreases and the Q value increases.At 100 kHz,the core loss of FeSiB magnetic cores is 152W/kg,while the core loss of composite magnetic cores with 8wt.% ferrite is 120W/kg,a decrease of 21.7%.In order to reduce the magnetic core loss,the second method is to prepare the FeSiB magnetic cores by composite coating of phosphate-silicone resin.The effect of phosphate-silicone resin composite coating,phosphating solution content and phosphating temperature on the properties of the magnetic powder core has been studied.Phosphate-silicone resin composite coating can effectively reduce the core loss of FeSiB magnetic cores.Compared with the untreated FeSiB magnetic powder cores,the magnetic core loss of the composite coating FeSiB magnetic powder cores is reduced by 30.8%,but at the same time,magnetic permeability of magnetic cores are also reduced.When the content of phosphating solution is 6wt.%,the composite coating FeSiB magnetic powder cores has the lowest core loss.Compared with the FeSiB magnetic cores,the composite coating magnetic cores is reduced by 38.5%.Phosphating temperature has great influence on the phosphate effect.150℃ has the best phosphate effect and the lowest er core loss,and the magnetic powder core permeability are higher comparatively.Therefore,when the phosphating temperature is 150℃,it has good comprehensive magnetic properties.