| Because of its superior DC-Bias,DC bias,low high frequency loss and excellent forming effect,FeNi powder core has irreplaceable advantages in many application fields,which is the hot spot of the research of magnetic particle core.In this paper,FeNi50 powder prepared by atomization is used,and then it is formed by pressure pressing and heat treatment by hydraulic press after insulation coating.The properties of the prepared FeNi powder core are tested and analyzed,and the factors affecting the properties of the core are analyzed.(1)The particle size of the powder has a great influence on the density of the core,which affects the DC-bias performance of the core.In this paper,1#、2#、3#、4#is adopted by the principle of grading.When pressing under 1963MPa,the density p of the pressed billet reaches 7.58g/cm3.The magnetic permeability of the magnetic powder core is 51.1 and the relative permeability retention ratio is 81.6%under the bias magnetic field with the relative permeability μc=62.6,At 7958A/m.The magnetic permeability of FeSi magnetic core with the same permeability is only 47.6 and the relative permeability retention ratio is only 76.0%under the bias magnetic field of 7958A/m.(2)The mass fraction of passivator affects the coating effect of FeNi particles,and then affects the Q value of quality factor and unit volume loss of the product.When the passivator concentration is 2.5wt.%,the maximum Q value of the FeNi magnetic powder core is 248mW/cm3 under the test conditions of 100kHz and 1.0V.The loss per unit volume of FeSi magnetic particle core is 686mW/cm3.(3)The temperature and holding time of annealing have the most influence on the relative permeability and unit volume loss of the FeNi powder core.When the annealing temperature is 700℃ and the holding time is 1 hour,the relative permeability μe of the magneticpowder core is 60 and the unit volume loss is 240mW/cm3. |
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