Interdiffusion behavior and lifetime prediction of Co-Al coating on Ni-based superalloy

The Co-Al coating was deposited on Ni-based superalloy DZ125 by pack cementation. The lifetime and interdiffusion behavior of the Co-Al coating on the Ni-based superalloy at 1050 degrees C, 1075 degrees C and 1100 degrees C were investigated. Surface oxidation and interdiffusion between the coating and the substrate led to depletion of Al in the coating, and beta-Ni(Co)Al was gradually degraded into gamma and gamma' phases. Oxidation activation energy of the coating was calculated through oxidation weight gain curves of different temperatures. The formula of the coating lifetime related to the coating thickness and the temperature was established by calculating intermediate parameters. The lifetime determined by the formula and experiment showed good agreement. (C) 2019 Elsevier B.V. All rights reserved.