Composite coatings with and without an in situ forming Cr-based interlayer: Preparation and oxidation behaviour

Two composite coatings with and without the Cr-based interlayer have been prepared. Isothermal oxidation at 1000, 1100 and 1150 °C as well as cyclic oxidation at 1100 °C has been performed on the two coatings. The results reveal that the improvements in oxidation properties are primarily ascribed to the inhibition effect of Cr-based interlayer on the inward diffusion of Al. In addition, diffusive transformation of Al and Ni, and the original presence of ReNi layer are believed to be responsible for the formation of Cr-based interlayer.

► Composite coatings with and without the Cr-based interlayer have been prepared.
► Oxidation properties are improved by the presence of Cr-based interlayer.
► The Cr-based interlayer inhibits the inward diffusion of Al.
► It is in situ formed in the ReNi layer by the inward diffusion of Cr atoms.