FeCo纳米晶吸波剂高温晶粒尺寸及电磁性能

High Temperature Grain Size and Electromagnetic Properties of FeCo Nanocrystalline Absorber

研究了热处理温度对片状FeCo纳米晶吸波剂表面形貌、晶粒尺寸、电磁和吸波性能的影响规律。结果表明,随着温度升高,FeCo纳米晶吸波剂的宏观形貌保持稳定,但晶粒尺寸不断增大:室温到300℃,晶粒尺寸随着温度的升高缓慢变大,从11.6nm增加到19.4nm;300℃到600℃,晶粒尺寸随温度的升高显著增大,在600℃热处理后达到54.5nm。由于晶粒长大和内应变降低,FeCo纳米晶吸波剂的饱和磁化强度随温度升高逐渐增大,而矫顽力则逐渐减小。吸波剂的电磁参数随温度升高有明显变化:复介电常数随温度升高逐渐增大,以低频复介电常数增幅最大;磁导率实部随温度升高总体呈下降的趋势;磁导率虚部随温度升高先增大后减小,且共振峰向低频偏移。模拟计算表明,涂层吸收强度随着热处理温度升高而逐渐降低。

The effects of heat treatment temperature on morphology,grain size,electromagnetic and microwave absorption properties of flaky FeCo nanocrystalline absorbents were studied.The results show that the morphology of FeCo powders rarely changed after heat treatment,whereas the grain size increased with the increase of temperature.From room temperature to 300℃,the grain size increased slowly from 11.6nm to 19.4nm;however,it increased rapidly to 54.5nm after heat treatment at 600℃.The saturation magnetization of FeCo nanocrystalline absorbents increased gradually with the increase of heat treatment temperature,whereas the coercivity exhibited contrary tendency.It was further found that the complex permittivity increased gradually with the increase of heat treatment temperature,especially at low frequency region.The real part of complex permeability gradually decreased with the increase of temperature.The imaginary part of complex permeability increased initially and then decreased,whereas the resonance peak shifted to low frequency with the increase of temperature.The simulated reflection loss of microwave absorbing material based on FeCo nanocrystalline absorbents weakened with the increase of heat treatment temperature.