Preparation and cyclic oxidation of gradient NiCrAlYRe coatings on Ni-based superalloys

Arc ion plating (AIP) and chemical vapor deposition (CVD) aluminizing were combined together to produce a gradient NiCrAlYRe coating. Elements in this coating were chemically graded with Al enrichment in the outer zone and Cr enrichment in the intermediate zone. Cyclic oxidation tests were performed at 1100 °C for up to 22 cycles. The results showed that the gradient NiCrAlYRe coatings performed better resistance to spallation and Al depletion than the conventional NiCrAlYRe coatings. This favorable oxidation behavior was attributed to the high Al distribution in the near surface region of the gradient coating.