Study On The Preparation And Properties Of Ferrite Graphene Composites Based On Thermal Reduction Method

In recent years,with the rapid development of modern electronics,it is more and more difficult for single materials to cope with the more complex electromagnetic environment,and the combination of new absorbing materials with traditional ferrite absorbing materials has become a hot topic.Ferrite materials have excellent ferromagnetism and electromagnetic wave absorption capacity,but they have the disadvantages of single absorption frequency band,single absorption mechanism and high density,which is difficult to meet the needs of electromagnetic environment under the new situation.Therefore,it is urgent to combine a new type of ferrite with other absorbing materials.As a new type of two-dimensional carbon nanomaterial,graphene has excellent electrical conductivity,thermal conductivity,low density and other characteristics,but it does not have magnetic properties.Its characteristics are fully complementary to the traditional ferrite wave absorption materials.Its recombination with ferrite can greatly improve the electron mobility,chemical stability,thermal conductivity and other chemical and physical characteristics of the composite material.In view of this,this study uses a high-temperature vacuum thermal reduction method to composite raw materials.This method can easily composite samples,and use the reducibility of carbon to form different interfacial layers to enhance the interfacial polarization of the samples.In order to study the effect of different ferrites on the interface between metal alloys,three typical ferrite materials,ferriferrous oxide,barium ferrite,and cobalt ferrite,were selected as graphene composite objects.ferriferrous oxide and cobalt ferrite have the same spinel structure,while ferriferrous oxide has no other elements,facilitating the study of the decomposition and reduction of ferrite at high temperatures.The cobalt ferrite has a spinel structure,and the incorporation of cobalt greatly improves the magnetic properties of the material.In contrast,barium ferrite,as a hexagonal structure ferrite,exhibits strong chemical stability,and its decomposition temperature at high temperatures is much higher than that of spinel structure.The specific content is as follows:（1）As a spinel structure,ferriferrous oxide is more easily reducible.Under the action of high temperature,Fe³⁺is rapidly reduced by carbon,resulting in the decomposition of ferriferrous oxide.As temperature rises,Fe²⁺is also redu ced,resulting in the formation of Fe elements,which in turn combine with car bon to form a Fe C interface,which in turn precipitates Fe and eventually deco mposes at high temperature.Therefore,at 300℃,500℃,700℃,and 1000℃,the phases are ferroferric oxide/carbon,ferroferric oxide/iron/graphite,ferroferric oxi-de/iron/iron carbide/graphene,and ferroferric oxide/iron/graphene,respectively.According to the test,when the iron carbide interface exists at 700℃,the sa mple has the strongest wave absorption performance,with a minimum absorpti on peak of-53.52 d B and an effective absorption bandwidth of 5.28 GHz.（2）The cobalt ferrite material is the same spinel structure,similar to that of ferriferrous oxide.It decomposes rapidly at high temperature,and the free iron produced quickly combines with cobalt and carbon,forming the interface between cobalt-iron alloy and iron carbide.With the further increase of temperature,the cobalt ferrite is finally completely decomposed into cobalt-iron alloy.Therefore,the phases of the samples at 230℃,600℃,and 800℃are:cobalt ferrite/cobalt ferroalloy/carbon,cobalt ferrite/cobalt ferroalloy-iron carbide/carbon,cobalt ferrite/cobalt ferroalloy/graphene,while the samples at 1000℃are entirely composed of cobalt ferroalloy.After detection,at 800℃,the sample has the highest absorption performance,reaching-48.80 d B,and the effective absorption bandwidth is 4.04GHz.（3）Barium ferrite as hexagonal structure,its stability is stronger than the spinite structure of ferrite,decomposition temperature is higher,produce a lot of barium oxide and metal iron,similar to ferriferrous oxide,iron and carbon mixed form iron carbide interface,after the iron carbide precipitation with the temperature,barium ferrite completely decomposition.Therefore,at 300℃,600℃,750℃,and 1000℃,the phases are:barium ferrite/carbon,barium ferrite/carbon,barium ferrite/barium oxide iron/iron carbide/graphene,and barium oxide iron/graphene,respectively.Furthermore,at 750℃,the sample absorption capacity is strongest,reaching-51.60 d B and effective absorption bandwidth up to 11.48 GHz.In this paper,we verified the feasibility of composite ferite graphene by the above three ferite materials,and study the influence of the reduction interface on the absorption properties,showing the unique advantages of thermal reduction method in composite different types of absorption materials.