Journal of Alloys and Compounds 527 (2012) 71–75 Contents lists available at SciVerse ScienceDirect Journal of Alloys and Compounds jou rn al h om epage: www.elsevier.com/locate/jallcom Electromagnetic and microwave absorption properties of surface modified Fe–Si–Al flakes with nylon Chuankun Zhang, Jianjun Jiang ∗ , Shaowei Bie, Li Zhang, Ling Miao, Xinxin Xu Department of Electronic Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China a r t i c l e i n f o Article history: Received 13 December 2011 Received in revised form 1 March 2012 Accepted 2 March 2012 Available online 7 March 2012 Keywords: Fe–Si–Al flake Surface modification Nylon 6 Microwave absorption Reflectivity a b s t r a c t The surface modified Fe–Si–Al alloy flakes with nylon 6 were prepared by a simple melt compounding method, and the electromagnetic and microwave absorption properties were presented. After surface modification, the complex permittivity of the flakes decreases dramatically with increasing amount of nylon 6, while the complex permeability remains nearly intact. The calculated microwave reflectivities show that surface modification is able to improve the microwave absorption performance of Fe–Si–Al flakes and that the composite containing modified flakes with an appropriate amount of nylon 6 is a promising candidate for a thin microwave absorbing material in S-band (2–4 GHz). © 2012 Elsevier B.V. All rights reserved. 1. Introduction Due to the rapid development of wireless communications and high frequency circuit devices in GHz range, electromagnetic inter- ference and electromagnetic radiation pollution have grown to a critical issue to be addressed. Therefore, microwave absorbing materials have attracted considerable attention because of their abilities to reduce and eliminate the electromagnetic radiation and interference [1–5]. Among the candidates for microwave absorbers, flake-shaped soft magnetic metallic powders are particularly inter- esting for their high permeability and high magnetic loss in GHz range originating from high saturation magnetization and large shape anisotropy [6–13]. High permeability and high magnetic loss are favorable for improving the microwave absorption properties in a low frequency band and for which the thickness of absorbing material can remain thin simultaneously [13–17]. Therefore, flake- shaped soft magnetic metallic powders are expected to achieve an effective microwave absorbing materials with thin layer thickness in GHz range. In recent years, flake-shaped Sendust (Fe–Si–Al) alloy powders have been extensively studied for microwave absorbing materials due to the high electrical resistivity, good machinability, excellent soft magnetic property and low cost [9,18–21]. However, a high permeability is generally accompanied with a high per- mittivity in flake-filled composites [9,18,22], which degrades the impedance matching and limits the absorption property to some ∗ Corresponding author. Tel.: +86 27 87544472; fax: +86 27 87544472. E-mail address: jiangjj@mail.hust.edu.cn (J. Jiang). extent [23]. Since surface modification is an effective way to sup- press the permittivity [16], it is believed that the modification of Fe–Si–Al flakes is of great significance to improve the microwave absorption property in GHz range. Until now, numerous studies have been performed for surface-modified magnetic metallic flakes to improve microwave absorption properties, such as SiO 2 coated Fe [24,25], ZnO coated Fe [26], Ce 2 O 3 coated Fe–Co [12], SiO 2 coated Fe–Ni–Mo [27], Fe–Ni coated with its oxide [16], Fe–Cu–Nb–Si–B coated with its oxide [28], and Fe–Co–Zr coated with polystyrene [29], and so on. However, most of these reports focused on inorganic oxides as the surface coating, and little attention has been paid to organ- ics for surface modification of Fe–Si–Al alloy flakes. Nylon 6, one of the most common organics, can be a potential candidate for surface coating because of its high adhesion and excellent insula- tion properties. Moreover, a better dispersion of inorganic powders in organic polymers can be achieved via surface treatment with nylon 6 [30], which improve the mechanical property of compos- ite. Hence, it is supposed that the surface modified Fe–Si–Al alloy flakes with nylon 6 could be promising candidates for application of microwave absorbing materials. In this work, we reported an effective method to fabricate Fe–Si–Al flakes coated with nylon 6 and investigated the elec- tromagnetic and microwave absorption properties after surface modification with different amounts of nylon 6. 2. Experimental details The Fe–Si–Al alloy flakes were prepared by the conventional mechani- cal milling process. Spherical Fe–Si–Al alloy powders with a composition of 9.5 wt%Si–5.5 wt%Al–bal. Fe (purchased from Advanced Technology & Materials Co., 0925-8388/$ – see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.jallcom.2012.03.009