Preparation And Soft Magnetic Properties Of FeSiBPNb Amorphous Soft Magnetic Powder Cores

Soft magnetic composite material is a new type of soft magnetic material with magnetoelectric conversion function.Among them,amorphous soft magnetic is a new type of soft magnetic material.Due to its excellent comprehensive performance,it has received extensive attention and research in academic and business circles in recent years.Amorphous soft magnetic composites are often obtained by coating the surface of amorphous powders with an insulating agent and then compression molding.However,the necessary conditions for preparing a good-quality amorphous powder are often severe,and a conventional amorphous soft magnetic composite material is used as a matrix powder by crushing the prepared amorphous ribbon into a powder.The broken powders of strips are usually irregular in shape and have sharp edges and corners.Such edges and corners are likely to cause loss of accumulation and sharp edges will cause destruction of the insulating layer during later pressing,and can easily damage the overall loss performance and affect the stability..With the trend toward miniaturization,energy saving,and high frequency of current electronic devices,newer and higher requirements have been put forward for amorphous soft magnetic materials,requiring that soft magnetic composites have higher saturation magnetic induction and higher permeability.Rate,lower loss and good high frequency stability.In this paper,an amorphous(Fe_0.76Si_0.09B_0.1P_0.05)₉₉Nb₁ soft magnetic material with high amorphous-forming capability was selected to produce a spherical powder as a matrix by gas atomization and the powder was analyzed by X-ray diffraction analyzer.Completely amorphous.By the method of TEOS hydrolysis,an SiO₂ insulating layer is formed in situ on the surface of the amorphous powder.SiO₂ has a high resistivity and can effectively reduce the loss of the soft magnetic material at high frequencies.Scanning electron microscopy was used to characterize the cross section of the coated powder with different TEOS concentration.The thickness of the coating was clearly visible with the TEOS concentration.As the concentration of TEOS increased,the coating gradually became thicker.Then,3 wt%of epoxy resin was used as a binder to prepare a ring-shaped amorphous soft magnetic composite material and the annealing performance was tested.The effect of TEOS concentration on the thickness of the insulating coating can be effectively controlled by controlling the concentration of TEOS,thereby obtaining a soft magnetic composite material with different properties.With the increase of TEOS content,the magnetic permeability of soft magnetic composites will decrease.All SiO₂-coated soft magnetic materials exhibit superior DC-bias performance over 70%of the magnetic permeability under an external field of 100 Oe.The different loss properties make it possible to select samples with a more suitable TEOS concentration within the required frequency range.In addition,innovative sol-like NiZn ferrite precursors were coated on the surface of the powder and amorphous soft magnetic composites with high hardness were prepared by spark plasma sintering?SPS?.The gel-like Ni Zn ferrite precursor is a non-magnetic material and can be coated on the surface of the amorphous powder very easily and uniformly compared to other methods.By utilizing the high temperature generated during the sintering of the SPS,the high temperature generated during the pressing process is converted into a spinel NiZn ferrite with good magnetic properties and electrical resistivity.The resistivity of the(Fe_0.76Si_0.09B_0.1P_0.05)₉₉Nb₁/NiZn ferrite prepared as compared with the uncoated insulating layer was increased by 74 times,the loss was significantly reduced,and the magnetic permeability also became more stable.SPS sintering was applied to the coated powder at three temperatures of 437°C,487°C,and 537°C.The comparison shows that at 487°C,the amorphous powder can still remain amorphous,and the ferrite precursor has the best performance when it is transformed into a spinel structure.