Development of a carbon-coated reticulated porous alumina material with tailored structural properties for potential radar-absorption applications

Abstract Porous ceramics have attracted research interest because of their high levels of thermal and chemical stability. Reticulated porous ceramics have been fabricated for several decades. However, insufficient data exists regarding the radar-absorption properties of reticulated porous ceramics. Therefore, the authors investigated the feasibility of using reticulated porous ceramics, prepared using alumina, as a platform for a radar-absorbing coating-material, such as carbon. The experimental data were used to determine whether carbon-coated reticulated porous alumina could be effectively prepared while maintaining an acceptable compressive strength by controlling the processing conditions. The structural properties and radar-absorption properties of the carbon-coated reticulated porous alumina material were examined using scanning electron microscopy (SEM), mercury porosimetry, and a network analyzer. The compressive strengths of the reticulated porous alumina specimens could be tailored by controlling the sintering temperature and the pore density of the polyurethane foams. The reflection loss of the reticulated porous alumina specimen with a thickness of 18.40 mm, coated with a carbon slurry with a carbon content of 10 wt%, was calculated as approaching −40 dB at 10.0 GHz.