Preparation and properties of cobalt oxides coated carbon fibers as microwave-absorbing materials

• Published in: Applied surface science 2011-06, Vol.257 (17), p.7678-7683
• Main Authors: Liu, Ying, Zhang, Zhongquan, Xiao, Songtao, Qiang, Chengwen, Tian, Liangliang, Xu, Jincheng
• Format: Article
• Language: English
• Subjects: Carbon fibers; Cobalt oxides; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Frequency ranges; Magnetic properties; Magnetic properties and materials; Magnetic properties of monolayers and thin films; Magnetic properties of surface, thin films and multilayers; Magnetization; Microwave absorbing materials; Physics; Precursors; Reflectivity; Saturation (magnetic); Structure and morphology; thickness; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thermal oxidation; Thin film structure and morphology
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2011.04.007

► Carbon fibers (CFs) are suitable substrates for electromagnetic absorption materials. ► Some carbon fiber-based composite materials have been developed for microwave absorption materials. ► Cobalt-oxides (CoO and Co 3O 4) are commonly used magnetic materials with good electromagnetic properties. ► Little work have been done to use cobalt-oxides as microwave absorption materials. ► We coupled cobalt oxides with carbon fibers to synthesis a new microwave absorption material. Cobalt oxides/carbon fibers (CoO x /CFs) composites were synthesized by thermal oxidation of cobalt coated carbon fibers (Co/CFs). The scanning electron microscopy images and X-ray diffraction pattern indicate that the layers are about 0.7 μm and composed of Co 3O 4 and CoO (CoO x ), the preferred condition for preparation of CoO x /CFs composites is to anneal Co/CFs precursors at 350 °C for 3 h in air. The coercivity, saturation magnetization and residual magnetization of the CoO x /CFs composites are 464.8 Oe, 10.62 emu/g and 2.21 emu/g, respectively. The reflectivity of cobalt oxides coated carbon fibers (1.11–5.12 mm in thickness) is less than −10 dB over the working frequency range of 4.04–18.00 GHz and less than −20 dB over 11.54–14.77 GHz. The lowest reflectivity is −45.16 dB at 13.41 GHz when the thickness is 1.50 mm.