Characterization of plasma sprayed nano-titania coatings by impedance spectroscopy

Nano-titania coatings were deposited via vacuum plasma spraying. The microstructure and chemical state of the coatings were investigated with SEM, TEM, XRD and XPS, respectively. The results showed that the vacuum plasma sprayed titanium oxide coatings possessed porous structure with small pores and agglomerated nanosized grains. The ac electrical data were measured in the frequency range 1 ⩽ f ⩽ 107 Hz at room temperature. The electrical data were analyzed with complex resistance and complex capacitance plots. The terminal resistance and capacitance were dissected with relation to the structure of the coatings. The depression observed in the planes was analysed in terms of nonuniformity in the measured reactance between the terminals.