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采用高能球磨和在微氧化气氛晶化热处理的方法制备钕铁硼吸波粉体,借助X射线衍射仪和微波矢量网络分析仪测量系统分析,研究Cr含量对钕铁硼粉体组织结构和微波吸收特性的影响。结果发现:高能球磨和微氧化气氛下进行600℃×2 h晶化处理后Nd11.76 Fe82.35 B5.88粉体组织由α-Fe,Nd2O3,Fe23(B.C)6相组成,加入Cr不改变NdFeB粉体的相组成,但可使粉体中的Fe23(B.C)6相对量减少,而α-Fe相对量增加;加入Cr可降低NdFeB粉体的复介电常数实部ε’和虚部ε″以及复磁导率实部μ’,尤其是Nd26.67Fe69.83Cr2.5B粉体的复介电常数虚部ε″降低得最多,加入Cr使NdFeB粉体的复磁导率虚部μ″在4～10 GHz频段时增大,而大于10 GHz频率后,复磁导率虚部μ″变化不大;吸波涂层厚度为1.5 mm时,Nd11.76Fe82.35B5.88粉体的反射率最小值约为-8.5 dB,吸收峰频率约为10 GHz;Nd26.67Fe69.83Cr2.5B反射率最小值降低到-17.0 dB,吸收峰频率升高到15.5 GHz,当将Cr含量增加到4%时,粉体的反射率最小值回升到-10.8 dB,吸收峰频率升高到15.8GHz;加入Cr会使NdFeB粉体的吸波带宽变窄。
NdFeB powder was prepared by high-energy ball milling and crystallization heat treatment in a micro-oxidation atmosphere. By means of X-ray diffraction and microwave vector network analyzer measurement system analysis, the effect of Cr content on the microstructure of NdFeB powder and microwave Effect of absorption characteristics. The results show that the microstructure of Nd11.76 Fe82.35 B5.88 powder is composed of α-Fe, Nd2O3 and Fe23 (BC) 6 phases after the high-energy ball milling and micro-oxidation at 600 ℃ × 2 h. Adding Cr Change the phase composition of NdFeB powder, but the relative amount of Fe23 (BC) 6 in the powder decreases, while the relative amount of α-Fe increases; adding Cr can reduce the real part ε ’and imaginary part of the complex permittivity of NdFeB powder Ε “and the real part μ ’of the complex permeability, especially the imaginary part ε” of the complex permittivity of the Nd26.67Fe69.83Cr2.5B powder are most decreased. When Cr is added, the imaginary part of the complex permeability of the NdFeB powder μ “increases in the frequency band from 4 to 10 GHz, but the imaginary part of complex permeability μ” changes little when the frequency is greater than 10 GHz. When the thickness of the absorbing coating is 1.5 mm, the Nd11.76Fe82.35B5.88 powder The minimum reflectance of Nd26.67Fe69.83Cr2.5B decreases to -17.0 dB and the frequency of absorption peak increases to 15.5 GHz. When the Cr content is increased At 4%, the minimum reflectivity of powder rose to -10.8 dB and the absorption peak frequency increased to 15.8 GHz. The addition of Cr reduced the absorption bandwidth of NdFeB powder.