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Short carbon fibers were treated at high temperatures around 1100°C through chemical vapor infiltration technology. A thinner layer of pyrocarbon was deposited on the fiber surface. The dispersion of carbon fibers in a cement matrix and the mechanical properties of carbon fiber/cement composites were investigated by scanning electron microscopy (SEM) and other tests. The reflec-tivity of electromagnetic waves by the composites was measured in the frequency range of 8.0-18 GHz for different carbon fiber contents of 0.2wt%, 0.4wt%, 0.6wt%, and 1.0wt%. The results show that the reflectivity tends to increase with the increase of fiber content above 0.4wt%. The minimum reflectivity is -19.3 dB and the composites exhibit wave-absorbing performances. After pyro-carbon is deposited on the fiber, all the reflectivity data are far greater. They are all above -10 dB and display mainly wave-reflecting performances.
Short carbon fibers were treated at high temperatures around 1100 ° C through chemical vapor infiltration technology. A thinner layer of pyrocarbon was deposited on the fiber surface. The dispersion of carbon fibers in a cement matrix and the mechanical properties of carbon fiber / cement composites were investigated by scanning electron microscopy (SEM) and other tests. The reflec-tivity of electromagnetic waves by the composites was measured in the frequency range of 8.0-18 GHz for different carbon fiber contents of 0.2 wt%, 0.4 wt%, 0.6 wt% , and 1.0 wt%. The results show that the reflectivity tends to increase with the increase of fiber content above 0.4 wt%. The minimum reflectivity is -19.3 dB and the composites exhibit wave- absorbing performances. After pyro-carbon is deposited on the all of the above reflectivity data are far greater. They are all above -10 dB and display mainly wave-reflecting performances.