Preparation Of Iron-nickel Alloy Composite Materials And Their Applications In The Field Of High-frequency

Iron-nickel alloys have been widely used in transformers,magnetic sensors,converters,microwave shielding or absorbing materials due to their high permeability,high saturation magnetization and low coercivity.For different applications,it is necessary to choose other materials compounded with iron-nickel alloys to achieve the application requirements.For the materials which need low energy loss in high frequency,a series of characterization and performance tests have been carried out in our study.On the one hand,the results show that the Fe-Ni@SiO₂ coated effect is ideal by activated micro-size Fe-Ni alloy with the help of the silane coupling agent for three times.Its value ofμ’is only 4.1,but the eddy current loss is the smallest and the quality factor is the highest in all of composite materials throught the high frequency range.On the other hand,the FeNi₃/NiZn-ferrite nanocomposite particles have been synthesized by hydrothermal method.The size of NiZn-ferrite particles which are nucleation and growth around FeNi₃ was different,also the coating effect.FeNi₃/NiZn-ferrite nanocomposites with a mass ratio of 8:1 have a relatively high saturation magnetization（87.6 emu/g）and a minimum coercivity（100 Oe）.At high frequency,its value ofμ’maintains at 11.8,and the quality factor is also the highest,which proves that its loss is the least.For the absorbing materials which need high loss in high frequency,on the one hand,it has been found that when the content of TEOS is 1 mL,the thickness of the synthetic FeNi₃@SiO₂ is about 25 nm.At this time,the composite materials could achieve the best absorbing performance,whose absorption intensity is-24.9 dB.FeNi₃@CS-2 composites have been synthesized by using low Co²⁺concentration to treat FeNi₃@SiO₂.The hollow structure between FeNi₃ core and Cobalt silicate sheet makes the specific surface area of FeNi₃@CS-2 composites larger.When the absorption layer thickness of FeNi₃@CS-2 composites is 1.2 mm,the maximum absorption intensity is-22.7 dB at frequency of 12.4 GHz and the bandwidth of loss exceeds-10 dB is 3.1 GHz.It makes absorbing materials thinner thickness,wider band and stronger absorption.On the other hand,the structure change of FeNi₃/NiZn-ferrite/C1 is the least when amorphous carbon is introduced with FeNi₃/NiZn-ferrite as raw materials.The FeNi₃/NiZn-ferrite/C1 composites exhibit stronger dielectric loss and magnetic loss in the high-frequency range.When the absorption layer thickness is 1.2 mm,the absorption intensity is larger（-16.9 dB）and the absorption bandwidth is wider（4.2 GHz）.