Xi’an, China
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Zeng J.,Xi An Engineering College | Xu J.,Institute of Materials Science and Engineering
Journal of Alloys and Compounds | Year: 2010

This letter reported that the CuO/Co/carbon fiber (CuO/Co/CF) composites were synthesized by thermal oxidation Cu/Co/carbon fiber composites. The results of scanning electron microscope images indicated that the diameter of the CuO/Co/CF composites was about 10 μm. The strongest reflectivity loss (RL) of the composites was further enhanced to -42.7 dB (microwave absorption rate >99.9%) at 10.8 GHz for a layer of 2.0 thickness, and the strong absorption (RL < -10 dB) was obtained between 8.72 and 18 GHz for the thickness of 1.3-2.2 mm. The CuO/Co/CF composites are believed to be ideal for making strong absorption microwave-absorbing materials. © 2010 Elsevier B.V. All rights reserved.

Zeng J.,Xi An Engineering College | Zeng J.,Northwestern Polytechnical University | Fan H.,Northwestern Polytechnical University | Wang Y.,Xi An Engineering College | Zhang S.,Xi An Engineering College
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2011

Copper-coated carbon nanotubes were prepared by the electroless plating route. The structure and component of copper/carbon tubes were characterized using a transmission electron microscope and energy dispersive spectrometer. The results show that the surface of the carbon tubes was covered by the copper particles. Copper/carbon tubes were used as the substitute of part of tin and all of lead in the tin bronze matrix, and the tribological properties of carbon nanotube-reinforced Cu-4 wt pct Sn-6 wt pct Zn composites were studied. The effects of the carbon nanotube volume fraction and sliding distance in unlubricated ball-on-disc wear test were investigated. The 3 vol pct carbon nanotube-reinforced Cu-4 wt pct Sn-6 wt pct Zn composite shows the Vickers hardness of 126.9, which is approximately 1.6 times higher than that of Cu-6 wt pct Sn-6 wt pct Zn-3 wt pct Pb tin bronze. The wear rate and average friction coefficients of 3 vol pct carbon nanotube-reinforced Cu-4 wt pct Sn-6 wt pct Zn composite were lower than those of the Cu-6 wt pct Sn-6 wt pct Zn-3 wt pct Pb tin bronze, respectively. © 2011 The Minerals, Metals & Materials Society and ASM International.

Jun Z.,Xi An Engineering College
Tribology Letters | Year: 2010

Copper-coated carbon fibers and carbon fiber (CF)-reinforced tin bronze matrix composites were prepared by chemical plating and powder metallurgy, respectively. Copper-coated CFs were characterized with field emission scanning electron microscope. The effects of CF volume fraction on the friction properties and tensile properties of the composites were investigated. The results showed that the composites exhibited lower friction coefficient and higher tensile strength than tin bronze 6-6-3 with the chemical composition of Cu-6 wt%Sn-6%Zn-3%Pb. The friction coefficient of the composites decreased with the increasing of the CF volume fraction. The composite with 9 vol.% CFs showed the highest hardness and tensile strength, which were, respectively, about 1.8× and 1.68× higher than those of the tin bronze 6-6-3. © 2010 Springer Science+Business Media, LLC.

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