Effect of chemical vapor deposition treatment of carbon fibers on the reflectivity of carbon fiber-reinforced cement-based composites

Short carbon fibers were treated through isothermal chemical vapor deposition technology at temperatures between 900 and 1200 degrees C. The fiber surface and the fracture surface of the carbon fiber-reinforced cement-based composite were observed by scanning electron microscopy. The influence of the fiber dispersion on the mechanical properties of the composites was investigated. The reflectivity of the composites against electromagnetic waves was measured in the frequency range of 8.0-18.0 GHz for carbon fiber contents of 0.2, 0.4, 0.6, 0.8, and 1.0 wt% by weight of cement. Results showed that before treatment, the reflectivity increased by 76.6% after the fiber content was over 0.4%. The minimum value was - 19.2 dB and almost 98% of the incident wave was absorbed. After treatment, the reflectivity decreased by 66.7% and all the values were always above -10 dB. The minimum data was -8.1 dB and 72% of the incident wave was absorbed. (c) 2007 Elsevier Ltd. All rights reserved.