Nondestructive characterisation of alumina/silicon carbide nanocomposites using impedance spectroscopy

Nondestructive evaluation (NDE) of ceramic matrix composites is essential for developing reliable ceramics for industrial applications. In the research described here, impedance spectroscopy has been used to characterise Al2O3/SiC nanocomposites nondestructively. Electrical modulus spectra from impedance measurements were used to determine the content of SiC nanoparticles in Al2O3/SiC composites. Meanwhile, electrical impedance measurements have been used to characterise the oxidation of Al2O3/SiC nanocomposites. Based on the microstructural features of the nanocomposites, equivalent models were developed to calculate the capacitance of the nanocomposites and oxidised specimens. The calculated results were used (i) to examine the relationship between the composition and electrical properties of the Al2O3/SiC nanocomposites; (ii) to predict the thickness of oxide scales formed at the surface of the nanocomposites after oxidation. The comparison showed reasonable agreements between theoretical prediction and experimental results.