Temperature Dependence of Electromagnetic and Microwave Absorption Characteristics of Co₂Si Alloy Powder AITranslate

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Basic Information:

DOI：10.13373/j.cnki.cjrm.XY25020008

Chinese Library Classification Number:TB39

Citation Information:

Electromagnetic waves play a vital role in human production and life. However，the increasing popularity and wide application of wireless communication systems and high-power motors have caused serious electromagnetic pollution，which poses a threat to human health and information security. Therefore，solving the problem of electromagnetic waves is one of the hot topics in scientific research. Absorbing material is a kind of functional material with special electromagnetic properties. Its core function is to absorb and transform the incident electromagnetic wave energy efficiently. It has important application value in high-tech fields such as electromagnetic protection，radar stealth and military camouflage. Studies have shown that cobalt materials not only have excellent dielectric loss characteristics，but also exhibit adjustable permeability characteristics in the GHz frequency band. These characteristics make it show great application potential in the field of electromagnetic wave absorption. In recent years，many researchers have carried out in-depth exploration on cobalt-based absorbing materials. By adjusting the microstructure of the materials and optimizing the preparation process，the electromagnetic wave absorption performance has been continuously improved，which provides an important idea for the development of a new generation of high-performance absorbing materials. In this paper，cobalt powder and silicon powder with high purity of 99.999 % were used as raw materials，and the ratio was based on the molar ratio of 2∶1 （Co₂Si）. The powder was ball milled by OECO-PBM-AD-6L all-round ball mill produced by Hunan Deke. In order to prevent the contact oxidation between the powder and the air in the ball mill during the grinding process，the air in the ball mill was first extracted by vacuum pump，and then the protective gas nitrogen （N₂）was filled into the ball mill. The prepared Co₂Si alloy powder was placed in a graphite oil tank and annealed in a vacuum tube furnace （GSL-1500X）at a heating rate of 5 ℃·min⁻¹. In order to prevent the oxidation of Co₂Si alloy powder during annealing，the air in the corundum tube was extracted by a vacuum pump and filled with argon （Ar），which was repeated 5~6 times. The annealing time was 2 h，and the annealing temperature was 500~900 ℃. The phase structure，microstructure，size，electromagnetic parameters and microwave absorbing properties of Co₂Si alloy powder samples were analyzed by characterization equipment and test equipment. The effect of annealing temperature on the electrical properties of Co₂Si alloy powder was studied. The results of X-ray diffraction （XRD）showed that Co₂Si alloy powder was successfully synthesized，and its crystal structure belongs to orthorhombic system. It could be observed that there are obvious diffraction peaks near the diffraction angles of about 44.10°，44.76°，45.34° and 53.68°，which correspond to the （210），（202），（013）and （203）crystal plane. The results showed that the synthesized material was Co₂Si alloy without Co and Si. Vibrating sample magnetometer （VSM）study showed that the saturation magnetization did not show a certain change rule. When the saturation magnetization increased from 500 to 700 ℃，the value decreased slowly，and the minimum value was 18.56 emu·g⁻¹ at 700 ℃. The maximum saturation magnetization was 36.14 emu·g⁻¹ when the temperature was increased to 800 ℃，and the saturation magnetization decreased again when the temperature was increased to 900 ℃. When the annealing temperature increases from 500 to 600 ℃，the coercivity gradually increased. However，in the range of 600~900 ℃，the coercivity gradually decreased with the increase of temperature. At 600 ℃，the maximum value was 380.25 Oe. The minimum value was 310.53 Oe at 900 ℃. The results of Vector Network Analyzer （VNA）study showed that when the annealing time was 2 h and the annealing temperature was 500~900 ℃，the prepared Co₂Si alloy powders all exhibited excellent microwave absorption properties. The minimum reflection loss values were below –10 dB，and the absorption efficiency of electromagnetic waves could be as high as 90%. When the annealing temperature was 600 ℃，the comprehensive absorbing performance of Co₂Si sample was the best. The minimum reflection was –32.22 dB，and the absorption efficiency of electromagnetic wave could be as high as 99.9%. In the frequency range of 2~18 GHz，the attenuation coefficient obtained by annealing at different temperatures increased with the increase of frequency. At 2~14 GHz，the attenuation coefficient of the annealing temperature of 600 ℃ was higher than that of other annealing temperatures. Therefore，when the annealing temperature was 600 ℃，its comprehensive absorbing ability was higher than that of other Co₂Si alloy powder samples.