Effective improvement of the properties of light weight carbon foam by decoration with multi-wall carbon nanotubes

In the present investigation, carbon foam (CF) has been decorated with multi-wall carbon nanotubes (MWCNTs) by two different routes to improve its electromagnetic interference (EMI) shielding effectiveness (SE) and mechanical properties. In the first case, a MWCNTs incorporated carbon precursor was used for the development of CF whereas in the other case, MWCNTs were directly grown over CF by a chemical vapor deposition (CVD) technique. These foams were characterized by scanning electron microscopy, Raman spectroscopy, X-ray diffraction and vector network analyzer for its EMI-SE. It was observed that, EMI-SE was dominated by reflection phenomena and it increased with an increasing MWCNTs content. The MWCNTs incorporated CF demonstrated a maximum EMI-SE value of −72 dB at 1 wt% MWCNTs. In comparison, MWCNTs directly grown on CF gives a maximum EMI-SE of −85 dB at only 0.5 wt% MWCNTs. The higher extent of improvement in EMI-SE in MWCNTs decorated CF was due to the increase in surface area and surface conductivity. The specific shielding effectiveness was 163 dB cm3 g−1 for MWCNTs decorated carbon foam of thickness 2.75 mm. This is the highest value reported in the open literature for CF in the X-band (8.2 to 12.4 GHz) frequency region. Moreover, besides EMI-SE improvement, compressive strength and thermal conductivity were increased by 66 and 75% respectively.