Microscale lamellar NiCoCrAlY coating with improved oxidation resistance

A novel NiCoCrAlY coating was fabricated by plasma activated electron beam-physical vapor deposition (PA EB-PVD). Within the duplex coating, the beta-NiAl phase precipitated as small lamellae (less than 1 mu m thick) in a gamma matrix, predominantly oriented perpendicular to the coating surface. The oxidation results at 1373 K show that the scaling rate constant during the steady-state oxidation of the novel coating is reduced by approximately 70% as compared with the conventional coating of similar composition produced by electron beam-physical vapor deposition (EB-PVD). This reduction in oxidation rate is attributed to a slower theta -> alpha Al2O3 phase transformation during the initial stages of oxidation. (c) 2012 Elsevier B.V. All rights reserved.