Characterization of the high temperature oxidation of TBC-coated oxide-dispersed β-NiAl substrates

A Y2O3−stabilized ZrO2 coating on three different oxide-dispersed (Y2O3, ZrO2 and Al2O3) β-NiAl substrates was studied to evaluate the spallation behaviour of the coating and its effect on the oxidation behavior of these alloy substrates. Spallation of the coating during cyclic testing at 1200°C primarily occurred at the Al2O3 scale-substrate interface and was dependent on the adhesion of the scale to the substrate. Uncoated, Y2O3−dispersed β-NiAl had the best Al2O3 scale adhesion and the coated β-NiAl substrate had the longest coating lifetime. Al2O3−dispersed β-NiAl exhibited the poorest scale adhesion and the coating completely spalled after two 2-hour cycles. For this model-type system, the growth of voids at the metal-scale interface appears to be critical in determining scale adhesion and thus coating lifetime.