Preparation And Wave Absorption Properties Of Nickel Matrix Composites Derived From Metal Coordination Polymers

With the rapid development of the electronic industry,a variety of electronic and electrical equipment are used in military,medical,communication and other fields.The existence of a large number of electromagnetic waves in space will not only affect the normal operation of electronic equipment,but also have a certain impact on people’s health.As a general strategy to improve electromagnetic interference,the researchers paid attention tothe electromagnetic absorbing materials.In order to develop absorbing materials with thin thickness,light weight,wide frequency band and strong absorption ".In this paper,we prepared NiO/Ni,Ni/C,NiO/Ni@PANI,Ni/C@PANI particles successfully,and studied the wave absorption properties of the above materials.The main contents are as follows:(1)Amorphous nickel metal coordination polymers(Ni-CPs)were synthesized by solvothermal method using m-phthalic acid.After calcining Ni-CPS at high temperature in air,NiO/Ni composite particles with spherical core-shell structure were obtained.NiO/Ni particles mainly depend on the dielectric loss of interface polarization and electric dipole polarization,and the magnetic loss of eddy current loss and natural resonance,as well as the multiple scattering mechanism of special structure to increase the electromagnetic wave absorption.When the filling proportion of NiO/Ni particles in the paraffin matrix is 50 wt%,the minimum value of reflection loss is-41.44 dB,the corresponding frequency is 16.5 GHz,the thickness is 5.5 mm,and the maximum effective absorption bandwidth is 1.94 GHz under the thickness of 5.5 mm.(2)The amorphous Ni-CPs particles were calcined in argon to produce Ni/C composites.In addition to the dielectric loss,magnetic loss and multiple scattering mechanism,the absorption of electromagnetic waves by Ni/C particles depend on a strong conductive loss,which was generated by a three-dimensional conductive network formed inside the Ni/C particles because of the carbon coated on the Ni particles after calcination at high temperature.When the filling proportion of Ni/C particles in paraffin wax is 50 wt.%,the minimum value of reflection loss is-21.2 dB,the corresponding frequency is 4.8 GHz,the thickness is 5.3 mm,and the maximum effective absorption bandwidth is 3.5 GHz under the thickness of 2 mm.(3)NiO/Ni@PANI and Ni/C@PANI composite were prepared by in-situ polymerization.As a kind of organic polymer material,polyaniline(PANI)has certain conductivity loss in electromagnetic field due to its good conductivity.The electromagnetic wave absorption performance of composites are improved by adding new material loss mechanism.When the filling proportion of NiO/Ni@PANI particles in the paraffin matrix is 20 wt%,and the thickness is 4.5 mm,the reflection loss is-67.1 dB at the frequency of 4.6 GHz,and the maximum effective absorption bandwidth is 2.1 GHz.When the proportion of Ni/C@PANI particles in the paraffin matrix is 20 wt%and the thickness is 3.1 mm,the reflection loss can reach-48.2 dB at the frequency of 8.8 GHz,and the maximum effective absorption bandwidth is 5.0 GHz.