Preparation And Microwave Absorbing Properties Of Nickel Matrix Composites

In recent years,more and more stringent requirements for stealth materials applied in weapons and equipment have been proposed because of the rapid advancement of radar detection technology and communication technology,such as stronger electromagnetic wave absorbing property,wider effective absorption band,low density,and corrosion resistance.Nickel（Ni）,as an excellent absorbing material,has the advantages of high saturation magnetization strength and strong magnetic loss capability.However,nickel still has some issues,such as easy corrosion,poor impedance matching performance,narrow absorption band,etc.which limits its application as an ideal electromagnetic wave absorbing material.Core-shell material is a new multi-component material that is divided into a core and a shell.By coating a shell on magnetic particle,the impedance matching performance can be improved,and the shell’s protective effect can be used to enhance the core’s corrosion resistance.Corrosion-resistant core-shell magnetic nanoparticles were prepared in this paper,and then graphene with large specific surface area were applied to load the above nanoparticles.The final component materials show excellent absorbing performance through the principle of multi-component coordination.The specific method is as follows:firstly,two-component core-shell structures were prepared by taking Ni nanospheres as the cores and silica layers as shells.Then the core-shell structures were coated with another layers of polyaniline to enhance their electrical conductivity and conductivity loss,and three-layer core-shell absorbing material were prepared.Finally,reduced graphene oxide（RGO）were introduced and the three-component core-shell absorbers are loaded on the surface of graphene sheets to further increase the conductivity loss,interfacial loss and corrosion resistance.The final absorbers are quaternary components with three-layer core-shell structures.The results show that three kinds of multi-component core-shell structure composites have been successfully prepared in this paper,and the absorbing properties of the composites become better and better with the increase of the components.The prepared binary core-shell structure Ni@Si O₂ achieves a minimum reflection loss of-9.05 d B which is an improvement over the single Ni nanoparticles;the Ni@Si O₂@PANI ternary composites were prepared by in situ polymerization,and the minimum reflection loss of-14.35 d B;The quaternary composites were prepared by covalent bonding,and the effect of RGO content on electromagnetic parameters and wave absorption properties was investigated.When 0.08 g RGO was added.The minimum reflection loss reached-38.60 d B.The magnetization strength of the composite material decreased by only 5.5%after 5 days of immersion in 1 mol/L hydrochloric acid,while the acid-treated absorbing material achieved a minimum reflection loss of-31.03 d B.