FeCoSi合金磁粉磷化处理及高频电磁性能

采用快淬甩带和高能球磨工艺制备了成分为Fe70Co12Si18(合金名称中数字为原子百分数)的片状合金磁粉,并用磷酸酒精溶液对磁粉进行了磷化处理。重点研究了磷化前后及不同磷酸浓度对FeCoSi磁粉电磁参数和微波吸收性能的影响。结果表明,随着磷酸浓度的提高,FeCoSi合金吸波材料的介电常数实部和虚部均减小,磁导率实部基本不变、虚部有少量减小,反射损耗(RL)增加。20%(质量分数)磷酸磷化样品在厚度为1.6 mm时的RL为-33.4 dB,带宽为5.2 GHz。高能球磨增加了磁粉的形状各向异性,使样品具有了较高的自然共振频率,且自然共振频率随着磷酸浓度的升高而进一步提高。样品经磷化处理后在表面生成了磷酸盐层,该磷酸盐层不仅通过增大材料的电阻率调控了样品的介电常数,有效改善了样品的阻抗匹配,同时向样品中引入了磁粉/磷化层等界面,增强了样品的界面极化作用。

High Frequency Electromagnetic Properties of FeCoSi Magnetic Powders via Phosphorization

Flaky Fe 70 Co 12 Si 18(atomic percentage)magnetic powders were prepared by quenching fastly combined with melt-spinning and high energy ball milling,followed by phosphorization with phosphoric acid alcohol solution.Effects of the concentration of the phosphoric acid solution on both the electromagnetic parameters and the microwave absorption performance of the FeCoSi powders was disclosed.With increased phosphoric acid concentration,both the real and imaginary parts of the permittivity decreased,while the real part of the permeability experienced subtle change with slight decrement for the imaginary part of the permeability.What’s more,enhanced reflection loss(RL)has been achieved with increased phosphoric acid concentration.The sample after 20%(mass fraction)phosporization exhibited optimal absorption with a minimum RL of-33.4 dB and a broad effective bandwidth of 5.2 GHz at a small thickness of 1.6 mm.The magnetic powder exhibited large natural resonance frequency due to the enhanced shape anisotropy after ball milling.The natural resonance frequency further improved with increased phosphoric acid concentration.The phosphate coatings fabricated on the surface of the powders after phosphorization not only effectively improved the impedance matching by increasing the resistivity and adjusting the permittivity of the material,but also enhanced the interface polarization by introducing interfaces between the powers and the phosphate layers.