Investigation Of Surface Modification And Corrosion Resistance Of Iron-cobalt Based Absorbing Materials

With the rapid development of modern science and technology,electromagnetic radiation pollution caused by the application of various electronic,electrical and communication equipment has become a new social nuisance and caused great concern.As a special material that effectively absorbs electromagnetic waves,the absorption material can transform electromagnetic energy to dissipate or allow electromagnetic waves to be eliminated in the form of interference.In the long run,the single component suction wave material cannot meet the needs of the band width,thickness and absorption,and the composite wave material will be a hot topic in the research of the absorption wave material.Due to the good absorbability,the iron cobalt substrate is widely used,but it also has the disadvantages of large density and high dielectric power,which usually increases the performance of its absorbability by doping compound with the material of the iron cobalt substrate.In this paper,aiming at absorbing material cost is high,the surface defects such as insufficient density,corrosion resistance,qualitative light,price low,resistance to high temperature of carbonyl iron（CIP）/Co composites as a raw material for surface treatment,the electromagnetic properties of composite absorbing material after surface treatment and corrosion resistant properties,first of all,the weak surface oxidation method of preparation of H₂O₂-CIP/Co,I-CIP/Co carbonyl iron two kinds of surface treatment（CIP）/Co composite absorbing powder,secondly using electroless Cu plating CIP/Co,Co plated CIP/Co two kinds of compound samples,The morphology,structure,electromagnetic properties and electrochemical properties of the samples before and after corrosion were tested and characterized.Finally,B and Nd-doped Fe/Co quick-quenching alloys were prepared by rapid quenching method,and B and Nd-doped Fe/Co composite absorbing materials were obtained.（1）by using carbonyl iron powder,coupling agent and cobalt powder,the method is prepared by the method of high energy ball grinding.（i）Weakly oxidize the surface of the CIP/Co composite absorbing material,and select two weak oxidants,hydrogen peroxide H₂O₂and iodine solution（I）,as the oxidizing medium.SEM shows that all samples have been oxidized by the weak oxidant.It has a certain degree of passivation,and the surface is covered in layers.When the matching thickness is 1.5mm,the CIP/Co composite material with weak oxidation treatment with iodine solution（I）has the best wave absorbing performance,with a frequency exceeding-5 d B.The bandwidth reaches 2.9GHz,and the reflection loss peak reaches a minimum of-8.4GHz at 2.2GHz.After simulation of the 5%Na Cl solution corrosion environment,the H₂O₂-CIP/Co composite material has better corrosion resistance and absorbing performance.（ii）CIP/Co was modified by electroless Cu and Co,respectively.The surface of the plate-like structure of the Cu-CIP/Co plated sample obtained was rough,possibly due to the clustering of the CIP/Co composite material.The surface smoothness is reduced,while the surface coating of Co-CIP/Co plating is smooth and unevenly distributed.The Cu-CIP/Co composite samples are better on the wave absorbing performance,and the frequency bandwidth exceeds-5 d B reaches 4.5GHz,and the reflection loss peak has a maximum value of-8.1 GHz at 4.3 GHz.The corrosion test shows that in a 5%Na Cl corrosion environment After moderate corrosion,the Co-CIP/Co composite material has better wave absorption performance than the Cu-CIP/Co composite material and CIP/Co raw material,and at the same corrosion potential,the corrosion current density is small,and its resistance Strong corrosion ability.（2）B,Nd doped FeCo alloy powder samples were prepared by fast quenching method,the structure of the sample,the phase of the object,the electromagnetic performance and the microwave absorptivity performance.The XRD graph analysis shows that only in all fast hardened samples.The sem shows that the size of the powder decreases with the increase of ball grinding time.Due to the increase of ball grinding time,the complex dielectric constant and complex permeability of the sample decreased gradually in the range of 2～18ghz frequency,and the minimum value of reflection loss was gradually reduced.The target of 4h doped FeCo alloy samples showed excellent suction performance in the frequency range,and the reflection loss peak at 3.8 GHZ was -9.8db.when the matching thickness was 1.5mm,the reflection loss peak was in the 3.8 GHZ.