Microstructure and Microwave Absorption Properties of Flame Sprayed Ceramic Coatings

In this research work, airplane grade aluminum alloy substrate was coated by Al2O3/ TiO2 ceramic coatings in two different compositions as 50:50 and 87:13 using Flame spraying technique. The surface & cross-sectional morphological characterizations of the Al2O3/ TiO2 powders and coatings were performed by scanning electron microscopy (SEM). The microwave absorbing properties of coatings were experimentally investigated using vector network analyzer in the frequency range from 8.2 to 12.4 GHz (X-band). The reflection loss values of Al2O3/ TiO2 coatings in 50:50 composition exceeding 10 dB (larger than 90% absorption) was achieved in the frequency range 9.28GHz to 9.82GHz with maximum reflection loss of -11.936dB at 9.53 GHz. It is observed that 87:13 composition of the ceramics Al2O3/ TiO2, gives more than 90% absorption in the frequency range 9.32GHz to 10.21 GHz with a reflection loss peak of -13.6 GHz at 9.683GHz.