ZrO2-nanoparticle assisted phase transformation and oxidation kinetics of thermally grown alumina on nickel aluminide coatings

In this study, a nanocomposite of Ni-ZrO2 was fabricated using composite electroplating. The fabricated nanocomposite was further aluminized by the process of pack cementation at 620 °C for 5 h. We examined the effect of ZrO2 nanoparticle dispersions in the Ni2Al3 on the oxidation kinetics and phase promotion of θ-Al2O3 to α-Al2O3 at high temperatures. The phase transformation, surface morphology, and oxidation behavior of ZrO2-dispersed Ni2Al3 were analyzed by Photo-stimulated luminescence (PSLS), TGA, XRD, and SEM, respectively. It was observed that as nano- ZrO2 content increased from 1 wt% to 5 wt% in the Ni2Al3 aluminide, the transformation of θ-Al2O3 into α-Al2O3 tends to became fast, resulting in an improvement in the low oxidation rate of the coating. In addition, the dispersion of ZrO2 nanoparticles in the Ni2Al3 matrix significantly mitigated the cavities and cracks at the interface between the aluminide and oxide scale, enhancing the interfacial strength.