| Soft Magnetic Composites(SMCs)is a kind of magnetic functional material prepared by uniformly mixing insulating coating agent and magnetic matrix,pressing into a specific shape by powder metallurgy,and then heat-treating.It has the advantages of low eddy current loss,high magnetic permeability,low coercivity,high resistivity,three-dimensional isotropy and easy machining,and can be made into corresponding shapes according to the ne EDS of the application.In recent years,with the country's vigorous development of green energy-saving materials,soft magnetic composite materials with the above-mentioned excellent properties are widely used in power electronics fields such as transformers,transformers,and reactors.The development of the third-generation wide-bandgap semiconductor has promoted the upgrading of power electronic devices and the improvement of energy utilization efficiency,and has also put forward higher requirements for magnetic inductance components based on electromagnetic induction effects,which are suitable for high saturation and low frequency at high frequencies.Lossy soft magnetic composites have become the focus of current research.In this paper,Fe-based soft magnetic composites coated with MgO,MgO/phenolic resin,AlN,AlN/phenolic resin were prepared by powder metallurgy using reduced Fe powder as the magnetic matrix.The effects of the microstructure,coating content and pressing pressure on the magnetic properties and crushing strength of the coated material were systematically and universally tested.The morphology of the powder matrix was regulated by mechanical ball milling,and AlN/phenolic resin-coated sheet-like Fe-based soft magnetic composites were prepared,and their surface morphology,composition and magnetic properties were characterized,and their magnetic properties were studied.Finally,a comprehensive comparative analysis of the samples with the best performance of different cladding materials was carried out.The following conclusions are drawn:(1)With the increase of MgO content,the density of the sample decreases gradually,the resistivity increases gradually,and the magnetic loss of the sample decreases,and the magnetic loss is the lowest when the content is 5%.When the magnetization field strength is0.05 T and the frequency is 100 k Hz,the magnetic loss value is 1044.68 W/kg,and the quality factor is 1.4,but the sample heats up more seriously,which affects the normal use of the sample.In order to reduce the loss and heat generation of the material and improve the pressing performance,the composite coated sample of phenolic resin and MgO was prepared.High permeability,lower magnetic loss and high quality factor,when the magnetization field strength is 0.05 T and the frequency is 100 k Hz,the magnetic loss of the sample coated with4%MgO/phenolic resin is 147.66 W/kg,which is comparable to Compared with the 5%MgOcoated sample,the reduction is 85.8%,and the quality factor is 8.5.(2)With the increase of AlN content,the density of the sample decreases,the resistivity increases,and the magnetic loss gradually decreases.When the content is 4%,the magnetic loss is the lowest.When the magnetization field strength is 0.05 T and the frequency is 100 k Hz,the magnetic loss is 1530.32 W/kg,and the quality factor is 1.3.Continuing to increase the frequency will cause serious heating of the sample and affect the normal use of the sample.In order to reduce the loss and heat generation of the material and improve the pressing performance,a composite coating sample of phenolic resin and AlN was prepared.When the magnetization field strength is 0.05 T and the frequency is 100 k Hz,the magnetic loss of the4%AlN/phenolic resin-coated sample is 131.84 W/kg,and the quality factor is 8.8.Compared with the 4%AlN-coated sample,the magnetic Loss is reduced by 91.3%.(3)The content of the coating agent AlN/phenolic resin was controlled to be 4%,the pressing pressure was 600 MPa,and the morphology of the substrate was changed by adjusting the ball milling time,and the effect of the morphology of the magnetic substrate on the magnetic properties was studied.The experimental results show that with the increase of grinding time,the density of the material decreases,the resistivity increases,and the magnetic loss gradually decreases first.When the ball milling time is 2 h,the prepared sample has relatively good magnetic properties.Under the condition that the intensity is 0.05 T and the frequency is 140 k Hz,the magnetic loss of the sample is 220.11 W/kg,and the quality factor is 7.21.Continuing to increase the grinding time will reduce the comprehensive performance of the sample;Compared with the properties of 4%MgO/phenolic resin and 4%AlN/phenolic resin samples,it is found that the samples ground for 2 h have the best magnetic properties;Compared with the samples prepared with Hegnas commercial coating powder,it is found that the magnetic loss of the matrix samples after grinding for 2 h is reduced by 72.11% when the magnetization field strength is 0.05 T and the frequency is 100 kHz. |
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