Preparation And Properties Of Polymorphous Carbon Based Microwave Absorbing Materials Composited Fe₃O₄ Nanoparticles

CCarbon material is an important research direction of microwave absorbing materials（MAM）.The high dielectric properties of carbon matrix will affect its microwave absorption performance.The impedance mismatch of carbon based microwave absorbing materials can be effectively solved by changing its morphology,structure and composite magnetic composition.Firstly,Fe₃O₄ Nps were prepared by solvothermal method.At different temperatures,carbonization of 2.5 times the pressure of melamine foam to obtain 3D skeleton MDFC.The MDFC/Fe₃O₄ composite absorbing material was mixed mechanically with Fe₃O₄Nps with different mass ratios.Morphology and structure of the composites were studied.To obtain more forms of carbon matrix and optimize more composite methods,two kinds of spherical carbon were prepared from phenolic resin.Phenolic resin carbon microspheres（CMS）composite Fe₃O₄（CMS/Fe₃O₄）and carbon coated Fe₃O₄ were prepared by mechanical mixing and in-situ polymerization（Fe₃O₄@C）;Based on the above research,in order to prevent the loss of Fe₃O₄ Nps in carbonation process,a new form of jujube cake structure polyurea aldehyde carbonization matrix（PUC）composite Fe₃O₄ Nps（PUC/Fe₃O₄）absorbing material was prepared by emulsion polymerization in the form of polyurea aldehyde（PU）.By Vector Network Analyzer.results show that MDFC/Fe₃O₄（CF）has 3D bone frame structure.The RL_min of CF64 can reach-19.0 d B;The RL_minof CMS/Fe₃O₄ is-17.5d B,Fe₃O₄@C RL_min under the optimum reaction conditions can reach-37 d B at least.The coating structure is conducive to the microwave absorption performance of the composite;The RL_min of“Jujube cake”PUC/Fe₃O₄-750 was-36.5 d B..From the above experiments,the morphology of carbon matrix and the composite mode with magnetic particles will impact on the properties of MAM,which provides a meaningful reference for the subsequent research on the morphology and structure design of polymer carbonized composite microwave absorbing materials.Figure 44;Table 2;Reference 81.