In this study, the measurement of magnetic and microwave absorption characteristics of MWNT (multi-walled carbon nanotubes) filled with Fe₃O₄ coated α-Fe nanoparticles and synthesized by dry mill using high energy milling have been performed. The sample was prepared from mixing of Fe and MWNT with a ratio of 10:1, then milled for 0, 5, 10, 15, 20, and 25 h respectively. The refinement results of X-ray diffraction pattern show that the sample have be formed MWNT/α-Fe@Fe₃O₄ nanocomposite which consists of C, α-Fe and Fe₃O₄ phases. Increasing milling time would generate an increasingly large α-Fe@Fe₃O₄ composite due to oxidation effect on the α-Fe powders surface. The morphologies of α-Fe@Fe₃O₄ particles were observed by TEM (Transmission Electron Microscopy) measurements. The particles, with lengths of up to at least 20 nm, have easily penetrated the nanotube cavity. The magnetic properties measurements show that the MWNT/α-Fe@Fe₃O₄ nanoparticles have a low coercivity field and a high remanence magnetization. The reflection loss of MWNT/α-Fe@Fe₃O₄ nanoparticles increases with increasing milling time. The MWNT/α-Fe@Fe₃O₄ nanocomposite achieves a reflection loss below −10 dB (70% absorption) at 10–11 GHz, and below −15 dB (80% absorption) at 12–13 GHz. Meanwhile the microwave absorbing peaks of composites containing MWNT/α-Fe@Fe₃O₄ nanoparticles shift to lower frequencies with increasing milling time.

在这项研究中，测量了填充有Fe ₃ O ₄涂层的α-Fe纳米颗粒并通过高能研磨通过干磨合成的MWNT（多壁碳纳米管）的磁和微波吸收特性。通过以10：1的比例混合Fe和MWNT制备样品，然后分别研磨0、5、10、15、20和25 h。X射线衍射图谱的细化结果表明样品已形成由C，α-Fe和Fe ₃ O ₄相组成的MWNT /α-Fe@ Fe ₃ O ₄纳米复合材料。延长研磨时间会产生越来越大的α-Fe@ Fe ₃ O ₄由于在α-Fe粉末表面上有氧化作用而形成复合材料。通过TEM（透射电子显微镜）测量观察到α-Fe@ Fe ₃ O ₄颗粒的形态。长度至少为20 nm的颗粒很容易穿透纳米管腔。磁性能测量表明，MWNT /α-Fe@ Fe ₃ O ₄纳米粒子具有低矫顽力场和高剩磁。MWNT /α-Fe@ Fe ₃ O ₄纳米粒子的反射损失随着研磨时间的增加而增加。MWNT /α-Fe@ Fe ₃ O ₄在10–11 GHz时，纳米复合材料的反射损耗低于-10 dB（70％吸收），而在12–13 GHz时则低于-15 dB（80％吸收）。同时，随着研磨时间的增加，含有MWNT /α-Fe@ Fe ₃ O ₄纳米颗粒的复合材料的微波吸收峰向低频移动。