Study On FeCo Based Magnetic Microwave Absorbing Material

While all kinds of developing electronic products bring convenience to people,they have also become the new resource of electromagnetic wave to radiation.A large amount of electromagnetic radiation will not only influence other electronic devices around to cause unpredicted consequences due to electromagnetic interference,but also affect health seriously.In addition,it is an available method for stealth technology that improve the combat efficiency and survival of weapon in wartime,so it attracts more and more attention from all countries as well.Whether to protect the environment and human health or to ensure the information and nation defense security,it is vital to study and improve microwave absorbing materials to enhance the ability of electromagnetic wave absorption.The microwave absorbing material is a kind of functional material which is able to absorb and attenuate electromagnetic wave,and it is usually composed of microwave absorbers and matrix.Metallic powders(Fe,Co,Ni)as well as their alloy that are used as microwave absorbers have been studied extensively,which is attributed to their high permeability and high saturation magnetization.Fe Co based alloys are the materials with high saturation magnetization and high Curie temperature so that have the application prospect as microwave absorbing materials at high temperature.The flaky structure of magnetic absorbers is benefit to break through the Snoek limit,and broaden the working frequency band of absorbing materials.However,pure Fe Co alloys have the characteristic of high hardness,so it is difficult to control their microscale and morphology.It is necessary to try to increase the brittleness of the alloy by micro-doping without reduction of its saturation magnetization excessively,so as to obtain magnetic powders with the desired morphology and microscale.We prepared the flake of Ge doped Fe65Co35 material by vacuum arc furnace melting and vibration ball milling and studied the ability of microwave absorption.It is found that for the sample of stoichiometric Fe6.5Co3.5Ge0.4,it is better than other samples which the ball milling time is 25 hours.At 2.76 GHz,the maximum reflection loss is-15 d B,and the coating thickness is 3 mm.Furthermore,by adjusting the content of Ge,we found that when the content of Ge is 2.488 weight percent,it has excellent microwave absorption capacity,and the maximum reflection loss at 3.6 GHz reaches-18.40 d B while the thickness is 3 mm.In summary,Ge doping can improve the brittleness of Fe65Co35,and benefit to obtain the structure of flaky powders.At the same time,it still has high saturation magnetization and Curie temperature above 850 ?,so it could be a potential absorber possessing high temperature resistant.