Preparation Of Fe-Si-B Amorphous Alloy Powder By Chemical Reduction Method And Its Wave-absorbing Properties

With the rapid development of electronic information technology,the radiation generated by electromagnetic waves not only affects the normal operation of electronic devices,but also poses increasingly serious risks to human health.Therefore,the absorption of electromagnetic waves has become particularly important.Iron-based amorphous alloys have a unique long-range disorder and short-range ordered structure,which endows them with excellent electromagnetic wave absorption characteristics and has broad application prospects in the field of microwave absorption.In this study,FeSi-B amorphous alloy powder was prepared by chemical reduction method.The composition of the powder was tested by ICP,while XRD and SAED were used to analyze the structure of the samples.SEM and TEM were used to observe the morphology of the powder,and the influence of preparation conditions on the product was investigated.The electromagnetic parameters of the samples were tested by VNA,and the reflection loss of the samples was calculated by the transmission line principle.The results showed that the powder had excellent electromagnetic wave absorption characteristics.The main research contents and conclusions are as follows:(1)Chemical reduction method can be used to prepare Fe-Si-B amorphous alloy powder in nano size.The Si content in the product can be regulated by changing the amount of Na2SiF6 in the reactants;while the B content can be regulated by adjusting the amount of NaBH4 involved in the reaction per unit time(dropping rate and concentration).With the increase of the amount of NaBH4 involved in the reaction per unit time and the rise of the reaction temperature,the oxidation of the product is intensified.The particle size of the obtained powder can be reduced by decreasing the amount of Na2SiF6 or increasing the amount of NaBH4 involved in the reaction per unit time.(2)In the frequency range of 2～18 GHz,the loss mechanism of Fe-Si-B amorphous alloy powder for electromagnetic waves is mainly magnetic loss,of which eddy current loss and natural resonance loss are the main components of magnetic loss.The magnetic loss first increases and then decreases with the increase of frequency.As the Si content decreases,the material’s ability to absorb electromagnetic waves first increases and then decreases,with impedance matching gradually decreasing and attenuation factor gradually increasing.With the increase of B content,the sample’s ability to absorb electromagnetic waves gradually increases,while impedance matching gradually decreases,and the attenuation factor remains relatively constant.The impedance matching of each sample gradually decreases with the increase of frequency,while the attenuation factor gradually increases.When the sample composition is Fe75.6Si1.4B23,the minimum reflection loss(RLmin)of the material is51.1 dB at 16.56 GHz and the matching thickness(dm)is only 1.5 mm.The effective absorption bandwidth(ΔfRL<-10dB)is 5.36 GHz(12.64～18.00 GHz).